BookPDF Available

VUNA: Valorisation of Urine Nutrients – Final Project Report

February 2015

Publisher: Eawag

Authors:

Bastian Etter

Vuna

Kai M. Udert

Swiss Federal Institute of Aquatic Science and Technology

VUNA – By recovering nutrients from urine, we want to develop a dry sanitation system, which is affordable, produces a valuable fertiliser, promotes entrepreneurship and reduces pollution of water resources.

At the Newlands-Mashu Field Test Site, multiple nutrient recovery technologies can be tested under realistic conditions. Besides the urine treatment plants, the containers host an analytical laboratory and a field office.

…

The fertilisers produced by the VUNA technologies can be directly tested on the fields at the Newlands-Mashu Test Site in eThekwini.

…

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…

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Content may be subject to copyright.

Content uploaded by Bastian Etter

Content may be subject to copyright.

Valorisation of Urine Nutrients

Promoting Sanitation & Nutrient Recovery through Urine Separation

Final Project Report 2015

2VUNA Final Report 2015

Overview

Valorisation of Urine Nutrients

Promoting Sanitation & Nutrient Recovery through Urine Separation

non-commercial purposes only (except when reproduction rights are

explicitly reserved), provided that mention is made of the authors and

this publication.

Cover picture: Glynn Erasmus, ERA design, Durban, South Africa

Photos: All photos from VUNA Project if not mentioned otherwise

Layout: Lydia Zweifel, Eawag

Printer: Binkert Buag AG, Laufenburg, Switzerland

Circulation: 2 000 copies printed on original recycled paper

Citation of this report: Etter, B., Udert, K.M., Gounden, T. (editors)

VUNA Final Report. Eawag, Dübendorf, Switzerland

3VUNA Final Report 2015

Project Team 36

Literature 38

Social and Economic Aspects

Social Acceptance 28

Campaigning for Health and Hygiene 30

Incentives for Urine Production 32

Business Model 34

Urine Collection Networks

Optimising Urine Collection 24

Performance Modelling 26

Agriculture

Fertiliser Trials 22

Risks of Using Urine

Removing Pharmaceuticals 18

Inactivating Pathogens 20

Urine Treatment Processes

Complete Nutrient Recovery 6

Nitrification 8

Distillation 10

Electrolysis 12

Struvite Precipitation 14

Process Control 16

4VUNA Final Report 2015

Introduction

Urine diversion in Durban

In 2002, the eThekwini Municipality – encompassing the greater

Durban area – introduced urine-diverting toilets to the under-serviced

communities inside the city’s recently extended metropolitan bound-

aries. This was a part of its overall strategy to provide sanitation for all

citizens. Urine-diverting dry toilets were chosen because providing a

pipe network and a treatment system for enormous supplementary

volumes of sewage would have been prohibitively expensive and im-

practical due to the hilly landscape. At the beginning of the campaign,

urine was not collected but instead was infiltrated into the ground

directly at the toilet. To date, about 82 000 urine-diverting toilets have

been installed in eThekwini. Although urine-diverting toilets met the

Municipality’s criteria for sanitation and sustainability, many users

were not satisfied with the new technology, due to the emptying

burden that was placed on the householder. Furthermore, infiltrating

urine into the ground risked polluting groundwater, lakes, and rivers.

Nutrient recovery to promote sanitation

In 2010, Durban’s water utility, eThekwini Water and Sanitation (EWS),

teamed up with Eawag to develop a new and improved sanitation

system that allows for nutrient recovery from urine in order to pro-

mote sanitation. Eawag has a long-standing, successful record of

research on nutrient recovery from urine in both low-income con-

texts (e.g. STUN Project, www.eawag.ch/stun) and in high-income

countries (Novaquatis Project, www.novaquatis.eawag.ch).

The project described in this report had three basic objectives:

• Promote the use of toilets by giving urine a value;

• Produce a valuable fertiliser;

• Protect the environment by reducing pollution.

The project was named VUNA, which means “harvest” in the isiZulu

language, but which also stands for “Valorisation of Urine Nutrients

in Africa”. By bringing together science and practice, the partners

aimed to develop the technologies and managements tools neces-

sary for the large-scale implementation of nutrient recovery from

urine in Durban and other cities facing similar sanitation challenges.

A trans-disciplinary team for a novel system

In order to cover the many specialist aspects of a novel sanitation sys-

tem incorporating nutrient recovery, the project team (p. 36) had

to involve several research institutes. The Pollution Research Group

(PRG) at the University of KwaZulu-Natal (UKZN) provided the scien-

tific resources and expertise for the field studies conducted in Dur-

ban. The studies on using incentives to promote urine collection were

conducted by the Centre for Development and Cooperation (NADEL)

at the Swiss Federal Institute of Technology in Zurich (ETHZ). The En-

vironmental Chemistry Laboratory (LCE) at the Swiss Federal Insti-

tute of Technology in Lausanne (EPFL) investigated the pathogens

occurring in urine and their inactivation during treatment. During the

course of the project, the Plant Nutrition Group at the ETHZ, and the

School of Agricultural, Earth and Environmental Sciences at the UKZN,

also joined the team in order to investigate how the end products

performed as fertilisers. Furthermore, at the UKZN, the School of

Agricultural, Earth and Environmental Sciences, and the School of

Nursing and Public Health, supported our research on social accept-

ance and health education.

VUNA—An Introduction

Promoting Sanitation and Nutrient Recovery through Urine Separation

Figure 2: Complete nutrient recovery – one of three nutrient recovery plants

built by the VUNA Project operates in Eawag’s basement. The two other

plants recover nutrients from urine in Durban.

Figure 1: Urine collectors measure and record the collected urine volume be-

fore they pick up the yellow jerry can from a urine-diverting toilet in eThekwini.

5VUNA Final Report 2015

Technologies for nutrient recovery from urine

Much of the research in VUNA focused on the treatment processes

for recovering nutrients from urine and the quality of their final prod-

ucts. The first of the three basic processes investigated was struvite

precipitation (p. 14), a simple procedure for phosphorus recovery. This

process had been tested in previous projects and was quickly imple-

mented; however, most of the nitrogen and virtually all other nutri-

ents remain unrecovered. The second process investigated was

complete nutrient recovery (p. 6) by combining nitrification (p. 8) and

distillation (p. 10). This process is more complex, but it recovers prac-

tically all the nutrients in one concentrated solution. The third process

was electrolysis (p. 12), which can be used for ver y small on-site treat-

ment units when nutrient removal, rather than nutrient recovery, is

the primary goal of treatment. Efficient treatment processes are cru-

cial for quality fertiliser products. In particular, the treatment must re-

move any harmful substances, such as pharmaceuticals (p. 18) or

pathogens (p. 20), and ensure good availability of the nutrients (p. 22).

More than just technology

Turning urine from waste into a valuable product requires more than

just technology. First of all, urine must be sourced and transported.

This means that urine-diverting toilets must become accepted by

the population, that urine collection is organised in an efficient and

reliable way, and that the overall system is economically viable. We

tested two basic urine collection schemes in the field. In an institu-

tionalised scheme (p. 24), municipal workers collected urine in jerry

cans from households. In the incentivised scheme (p. 32), toilet

users were compensated with monetary incentives when they

dropped off their urine jerry cans at local collection points. Using

computer models (p. 26), we aimed to minimise the costs for both

collection schemes. Estimates of urine treatment costs and fertilis-

er sales revenue became the input data for a business model (p. 34).

User surveys assessed the acceptance (p. 28) of the urine diversion

concept and, especially, the toilets. An inadequate understanding

of the rationale behind urine diversion was often the reason for low

acceptance rates for the toilets. Furthermore, we developed inter-

active health and hygiene education methods (p. 30) to improve the

acceptance of urine diversion and of sanitation in general.

Scaling-up nutrient recovery programmes

The VUNA Project covered the multiple aspects of developing and

implementing a novel sanitation system incorporating nutrient re-

covery from urine. A first pilot system was set up in eThekwini and

today further up-scaling is planned. The challenges of expanding

from a pilot scheme to a full-scale programme lie firstly in the col-

lection logistics and management, which strongly influence the

system’s costs. Secondly, the urine treatment plants require reliable

process control (p. 16) to ensure the continuous production of high

quality fertilisers. Finally, acceptance by the toilet users themselves

must increase. Overall, the project has received a lot of attention

from researchers and practitioners in South Africa, Europe and

around the world. In fact, the Swiss Federal Office for Agriculture

recently granted a license for the fertiliser produced using the

VUNA Project’s complete nutrient recovery process. This is another

valuable endorsement for VUNA ’s nutrient recovery process – har-

vesting urine from a sanitation system, reducing environmental pol-

lution and turning waste into a valuable, marketable product.

Figure 4: The fertilisers produced by the VUNA technologies can be directly

tested on the fields at the Newlands-Mashu Test Site in eThekwini.

Figure 3: At the Newlands-Mashu Field Test Site, multiple nutrient recovery

technologies can be tested under realistic conditions. Besides the urine treat-

ment plants, the containers host an analytical laboratory and a field office.

6VUNA Final Report 2015

Urine Treatment Processes

• Three pilot plants produce fertiliser from urine in

Switzerland and South Africa.

• Careful process control ensures stable nitrification.

• Biological nitrification successfully prevents malodour

and nitrogen loss.

• The combination of nitrification and distillation

concentrates all nutrients into one final product.

• Besides fertiliser, treatment plants produce distilled water.

Figure 1: Plastic biomass carriers provide support for the nitrification bacteria.

The nitrification and distillation plant in Eawag’s basement is one of three pilot plants producing liquid fertiliser from urine.

Complete Nutrient Recovery

The All Nutrients Solution

From theory to laboratory testing

The biggest part of the valuable nutrients excreted by the human

body is found in urine. Researchers have tested various technolo-

gies to extract these nutrients and produce fertiliser. However,

most of these technologies aim to recover specific nutrients, mean-

ing that the majority remains in the effluent. Complete recovery is

an alternative approach: instead of removing nutrients, water is

removed, and nutrient loss is minimised. Distillation is an optimal

water removal process (Distillation, p. 10). However, the urine must

first be stabilised in order to prevent the most important nitrogen

compound – ammonia – from volatilising, which causes environmen-

tal pollution and malodour. Biological nitrification is a resource-ef-

ficient process used to stabilise nitrogen (Nitrification, p. 8). We

previously tested this process in Eawag’s laboratory and succeed-

ed in adapting nitrifying bacteria to the high nutrient concentrations

found in urine. After this basic proof of concept, we designed and

built pilot plants in order to gain practical experience of the process

at a realistic scale.

VUNA pilot plants

The first pilot plant was installed in Eawag’s main building, near Zurich.

Urine was collected using urine-diverting toilets and waterless urinals.

Approximately 100 litres of urine were collected per working day for

use in fertiliser production. Based on the pilot plant, we built two fur-

ther plants in eThekwini, South Africa: one at a field test site in New-

lands-Mashu and one at the eThekwini Water and Sanitation (EWS)

Customer Care Centre in Durban. The pilot nitrification plants consist

of one or two plastic columns, each holding 120 litres of liquid. The

columns contain suspended plastic biofilm carriers that support the

Peter Penicka, Eawag

7VUNA Final Report 2015

Figure 3: eThekwini’s Customer Care Centre in Durban produces its own

fertiliser from urine.

Figure 2: Bacteria in an aerated column stabilise the urine before the liquid

is evaporated in a distiller.

Ion Concentration

Nitrogen (N) 50 g/L

Phosphorus (P) 2.1 g/L

Potassium (K) 15 g/L

Sulphur (S) 1.6 g/L

Calcium (Ca) 0.4 g/L

Magnesium (Mg) 0.04 g/L

Iron (Fe) 0.5 mg/L

Copper (Cu) 0.3 mg/L

Zinc (Zn) 15 mg/L

Boron (B) 16 mg/L

Key figures

Nitrogen recovery > 99 %

Recovery of other nutrients (e.g. P, K) 100 %

Liquid fertiliser produced from 1 000 L urine 30 L

Typical ammonia oxidation rate (as NH4-N) 400 to 800 mg/L/d

Electricity consumption for distillation 80 Wh/L urine

Electricity consumption for nitrification 50 Wh/L urine

Temperature range in the distiller

(boiling point at 0.5 bar) 80 to 85 °C

growth of the nitrification bacteria (Figure 1). Stabilised urine from the

nitrification columns flows into an intermediate storage tank, from

where batches of solution are fed into the distiller. The distillation

process concentrates the urine – and its nutrients – into a concentrated

nutrient solution. Distilled water leaving the process is the sole by-

product: it contains only traces of organic compounds and less than

1 % of the urine’s total nitrogen.

Continuous fertiliser production

A nitrification plant takes between 45 and 60 days to start up. Dur-

ing this time, the bacteria – taken from a conventional wastewater

treatment plant – must adapt to the very high nitrogen and salt con-

centration in urine. After this phase, the bacteria in the pilot plant

transform between 400 and 800 mg of nitrogen from ammonia into

nitrate per litre of plant volume per day. At Eawag, urine typically has

an ammonia concentration of 1 800 mg/L (as nitrogen), meaning that

50 litres of urine can be treated each day. After biological treatment,

the nitrogen is stable in solution (due to the combined effects of a

reduction in pH and nitrate formation). There is no malodour caused

by ammonia and organic compounds, and all the nutrients (nitrogen,

phosphorus, potassium, sulphur, and numerous micronutrients)

remain in the solution. In the ensuing distillation process step, 97 %

of water is removed. Potential pathogens are killed because the

solution is heated to 80 °C for at least half an hour.

Ensuring high process stability

Three years of pilot plant testing proved that the process was

suitable

for complete nutrient recovery from urine. Moreover, we were

also

able to establish all the necessary requirements for stable process

operation. Controlling the urine dosage rate and maintaining a constant

pH in the nitrification plant proved crucial for stable process perfor-

mance. Sudden changes in pH can lead to the accumulation of nitrite,

which destabilises the biological process and leads to high nitrogen

losses during distillation. The final product is a highly concentrated nu-

trient solution that compares well to commercial liquid fertilisers in

terms of nutrient concentrations. Although a supplementary process

step could produce a solid fertiliser product, the VUNA Project does

not recommend it: not only do solid deposits due to precipitation

complicate the drying process, but the solid end product is not ther-

mally stable. Hence, this process has been specifically designed to

produce a liquid fertiliser and – as a by-product – distilled water.

Table 1:

The final fertiliser

product contains all

necessary nutrients

for plant growth.

The urine was sourced

from the women’s

urine tank at Eawag’s

main building. With

other urine sources, the

nitrogen content can be

a factor two higher.

Luzius Etter, Adyessa

8VUNA Final Report 2015

Urine Treatment Processes

Figure 1: Nitrification lowers the pH in urine, preventing ammonia from volatilising.

Trough experimentation, we observed how ammonia, nitrite, and pH influence the bacteria in the treatment processes.

Nitrification

Stabilising Nutrients in Urine

• Biological nitrification prevents nitrogen losses and

removes malodour.

• Stable nitrification is possible if the pH is kept within a

narrow range.

• Overloading the nitrification plant with urine generates

toxic nitrite.

• Underloading the nitrification plant produces acid

and harms nitrifying bacteria.

Bacteria stabilise urine

Urine collected in urine-diverting toilets or urinals contains bacteria

that convert urine into a malodourous liquid with high concentra-

tions of volatile ammonia (NH3). To prevent ammonia from volatilis-

ing, and to simplify urine handling, the solution has to be stabilised.

One option is a biological process well-known in municipal waste-

water treatment: nitrification. In this process, bacteria oxidise half

the ammonia into non-volatile nitrate (NO3-

) and, as the pH drops, the

other half is stabilised as non-volatile ammonium (NH4+) (Figure 1).

Two bacterial groups share the work: ammonia-oxidising bacteria

produce nitrite (NO2-

), and nitrite-oxidising bacteria convert nitrite

into nitrate (Figure 2). A third bacterial group (heterotrophs) removes

the organic substances that are responsible for the malodour. The

process requires a good balance between ammonia-oxidising and

nitrite-oxidising bacteria, otherwise nitrite accumulates and inhibits

the nitrite-oxidising bacteria. Temperature and pH are the essential

parameters in nitrite accumulation.

Learning about urine nitrification

The pilot-scale nitrification plants in Switzerland and South Africa

(Complete Nutrient Recovery, p. 6) allowed us to learn more about

the functional stability of the nitrification process. Based on these

studies, we designed and conducted well-controlled experiments

in the laboratory. In short-term experiments, we determined how

ammonia, nitrite, and pH influence the activity of ammonia-oxidis-

ing and nitrite-oxidising bacteria. The results were integrated into a

computer model used to simulate a wide range of operating condi-

tions. Comparing simulated results with actual measurements is a

common scientific means to better understand bacterial process-

es, and such models allow the optimisation of plant operation, for

example, during the start-up phase. We also conducted longer-term

9VUNA Final Report 2015

––

–

Ammonia oxidation

NH3 + 1.5 O2 g NO2 + H+ + H2O

(ammonia+oxygen gnitrite+protons+water)

Nitrite oxidation

NO2 + 0.5 O2 g NO3

(nitrite+oxygen gnitrate)

Key figures

Final ammonium to nitrate ratio 1:1

Substrates and inhibitors of free ammonia (NH3),

nitrifying bacteria nitrite (NO2-)

Optimal pH for urine nitrification 5.8 to 6.5

Lower pH limit for common

ammonia-oxidising bacteria

(without acid adaptation) 5.5

pH causing release of harmful gases

(through chemical nitrite oxidation) < 4

experiments to better understand the causes of another possible

process failure: if the nitrification plant receives insufficient urine

for an extended period of time, the pH can drop to as low as 2.

Staying steady

Optimal nitrification requires that the bacteria receive a steady sup-

ply of urine and that the pH remains within a narrow range. The pH

is a critical parameter because it determines the concentration of

substrate for the ammonia-oxidising bacteria: they consume ammo-

nia (NH3) rather than ammonium (NH4+). When the influent urine

dose rises suddenly, extra ammonia becomes available; ammonia-

oxidising bacteria boost their activity and nitrite accumulates. If this

is noticed early, the problem can be solved by switching off the dos-

ing pump. Ammonia-oxidising bacteria keep producing nitrite until

they are inhibited at a low pH (5.5). Since nitrite-oxidising bacteria

are less sensitive to low pH, they will then oxidise surplus nitrite.

Conversely, if urine supplies are insufficient over an extended peri-

od of time (e.g. holidays), acid-tolerant ammonia-oxidising bacteria

may start growing. When this happens, pH can drop to 2, and com-

mon ammonia- and nitrite-oxidising bacteria will die off. This situa-

tion also produces harmful nitrogen oxide gases due to chemical

nitrite oxidation.

Nitrate

Ammonium

Nitrite

1250

1000

750

500

250

020406080

Nitrogen concentration [mg/L]

Time [days]

Figure 2: A plastic biofilm carrier used as a support for nitrification bacteria

and the biochemical reactions occurring on it. Nitrification is an interplay

between ammonia-oxidising bacteria and nitrite-oxidising bacteria (or chemi-

cal nitrite oxidation at low pH values).

Figure 3: The intermediate nitrite accumulates after a sudden increase in

urine dosage.

Figure 4: In a laboratory scale nitrification plant, we determined how

ammonia, nitrite, and pH influence the activity of ammonia-oxidising and

nitrite-oxidising bacteria.

Towards a robust process

These experiments and simulations showed the importance of sta-

ble conditions for nitrification. In practise, this can be achieved with

careful process control. The two parameters which have to be kept

within narrow ranges are pH and nitrite levels. While pH sensors are

common in wastewater treatment plants, real-time nitrite sensors

for the high concentrations expected in urine nitrification are not

available yet and new technologies will have to be developed

(Process Control, p. 16). Two other parameters which can influence

the process are urine dosage and aeration. Adequate process con-

trol strategies can be tested using the computer model developed

for this study, and they will support decision-making on means to

avoid both over- and underloading the nitrification plant. Including

the continual measurement of the storage tank’s urine level into an

overall process control strategy would help to ensure that urine

volumes never over- or underload the process.

10 VUNA Final Report 2015

Urine Treatment Processes

• Distillation efficiently concentrates urine nutrients into

a liquid fertiliser.

• Nitrogen loss during distillation is very low (below 1.5 %,

if the initial pH value is 6).

•

Producing liquid ammonium nitrate is safe as the maxi-

mum operating temperature is far below the critical 165 °C.

• Solid ammonium nitrate must not be produced at

temperatures above 96 °C, to avoid risk of explosion.

• Complete nitrification to nitrate (by adding calcium

carbonate) increases thermal stability.

Distillation

Water Removal from Nitrified Urine

Converting urine into a concentrated nutrient product

After source-separated urine has been stabilised by the nitrification

process (Complete Nutrient Recovery, p. 6; Nitrification, p. 8), the

nitrified urine is distilled in order to reduce its volume, thus mini-

mising costs for storage and transportation. There are a number of

reasons why we chose distillation as the process for concentrating

nitrified urine: nearly all the water can be removed; the energy re-

quired is comparatively low in distillers using energy recovery (e.g.

vapour compression and heat exchange); distillers are easily avail-

able, off-the-shelf products; and the high-temperature process

pasteurises the solution. However, at the beginning of this project,

there was only a very small body of knowledge on the distillation of

nitrified urine, and a number of unanswered questions remained.

How much water could be removed before salts precipitate? Could

unwanted substances, such as sodium chloride, be removed through

stepwise distillation? Would any nutrients be lost to the gas phase?

Which safety issues should be considered when distilling an am-

monium nitrate solution?

Figure 1:

State-of-the-art

distiller with vapour

compression featuring

90 % energy recovery

used in our pilot plants

(KMU-LOFT Cleanwater GmbH).

Distillation experiments in the laboratory investigated how salts precipitate in nitrified urine.

11VUNA Final Report 2015

Temperature [°C]

Energy release per g sample [mW/g]

Synthetic urine with NO3 only

Synthetic urine with NH4NO3

050100 150200 250 300 350

In the laboratory, in silico, and at the pilot scale

Laboratory experiments were used to investigate how water

content and temperature determine when salts start precipitat-

ing in nitrified urine. Further laboratory experiments were used to

measure how much volatile ammonia is lost during distillation. In

collaboration with Swissi, an institute specialised in safety assess-

ments, we conducted state-of-the-art calorimetric measurements

that enabled assessments of the thermal stability of the distillation

products. All these laboratory experiments were conducted in par-

allel, using samples of real nitrified urine, but also using synthetic

solutions or solids. Using the latter enabled adjustments to be made

to specific critical properties, such as ammonium and chloride con-

tent. Additional computer modelling was used to validate certain

experimental results and to analyse effects which were not verifi-

able using laboratory experiments alone. Last but not least, we

gained a wealth of experience by operating an industrial-sized dis-

tiller for more than three years using real nitrified urine (Complete

Nutrient Recovery, p. 6).

Critical operating temperature

Using distillation, 97 % of the water in nitrified urine can be removed,

yet all the salts remain in solution. Sodium chloride is the first salt to

precipitate and 50 % of it could be removed without losing consider-

able amounts of nutrients using stepwise distillation. This can be

beneficial for the final product’s use as a fertiliser, but does not help

to improve thermal stability; even at low concentrations, chloride

acts as a catalyst for ammonium nitrate decomposition at high tem

peratures. Measurements also showed that less than 1.5 % of the

ammonia present is lost by volatilisation, if the nitrified urine dis-

tilled has a pH value of 6. Besides ammonia, only traces of carbon

dioxide and organic substances were found in the condensate.

Finally, the safety assessment concluded that a maximum operat-

ing temperature of 96 °C should be used while producing solid

ammonium nitrate. Higher operating temperatures can be used,

however, when producing a liquid ammonium nitrate solution

(165 °C) or if all or nearly all ammonia is nitrified to nitrate with the

help of base dosage (see Key figures).

Keep it liquid

These studies proved that distillation is a feasible technology with

which to recover virtually all the nutrients in nitrified urine. They also

showed that the distillate contained only small amounts of ammo-

nia and organic compounds. These could be easily removed by strip-

ping, thereby producing another valuable product: distilled water.

Producing a liquid concentrate, instead of a solid, has substantial

advantages: the process is safer and the operation is simpler, given

that no scaling occurs. Liquid fertilisers might well also have a high-

er market value than solid ones (Business Model, p. 34), and they

comply with the legal standards for ammonium nitrate fertilisers.

The concentrated liquid samples used for the safety assessment

had sufficiently low ammonium nitrate concentrations (8.7 % nitro-

gen) to meet the legal requirements for fertilisers (max. 16 % nitro-

gen according to European and South African legislation). In the

case of the dried product (> 16 % nitrogen), the fertiliser could only

be sold to certified professionals in Europe or would have to be

mixed with 20 % of ground limestone in South Africa.

Figure 2: Energy released from solid samples heated in a RADEX device

(RApid Detector for EXothermic processes).

Figure 3: About 800 mL of concentrate or 600 g of dry solids can be

produced from 20 L of nitrified urine.

Key figures

Maximum water removal from nitrified urine

(ammonium nitrate) 97 %

Maximum sodium chloride removal from nitrified urine

(ammonium nitrate) 50 %

Distilled liquid Nitrogen loss

Stored urine (pH 9) 93 %

Nitrified urine (pH 6) 1.5 %

Final product Maximum operating temperature

Solid ammonium nitrate 96 °C

Liquid ammonium nitrate 165 °C

Solid nitrate > 360 °C

12 VUNA Final Report 2015

Urine Treatment Processes

Electrolysis

Electricity Treats Urine

• Electrolysis rapidly removes ammonia and organic

substances from urine.

• Electrolysis is well suited for decentralised urine

treatment in compact units.

• Phosphorus can be recovered efficiently using electro-

chemical magnesium dosage.

• Biological nitrification becomes more robust when nitrite

is controlled electrochemically.

Flow meter

Gas meter

Wash

bottles:

Air pump

Electrolysis cell Sample

Sample

1 2

Electrolysis downsizes treatment units

Many chemical and biological processes involve the transfer of

electrons. In electrolysis, the electron transfer occurs at the sur-

face of an electrode as soon as a power source supplies the re-

quired energy. When this occurs, the electrical current drives the

conversion of certain chemical compounds into new compounds.

This has multiple advantages, especially for decentralised urine

treatment in compact units: the technology is reliable; the conver-

sion processes can be fast; and the processes can be directly con-

trolled by applying a specified current or voltage. The real challenge,

however, is to specifically convert unwanted into wanted substanc-

es. This is particularly difficult with urine: because numerous sub-

stances are present, defining the exact conditions at which only

the desired processes take place is complex. The consequences

of unwanted processes may be energy losses or the formation of

harmful by-products. Our research investigated how to use elec-

trolysis to create specific chemical conversion processes in urine.

Multiple options to treat urine

In laboratory experiments, we explored three applications of elec-

trolysis for urine treatment. Firstly, we tested the electrochemical

oxidation capacity of three different types of electrodes – boron-

doped diamonds (BDD), iridium dioxide (IrO2), and graphite – to de-

grade ammonia and organic substances. The aim of this process

was to prevent environmental pollution and malodour. Secondly, we

combined an electrolysis cell, containing graphite electrodes, with

a biological nitrification plant. This combination stabilises the nitri-

fication process, as surplus nitrite (Nitrification, p. 8) is degraded

Figure 1: Wash bottles filled with an organic solvent trapped volatile

chlorination by-products emitted by an electrolysis cell.

How can electrolysis be used to create specific chemical processes in urine? Experiments on by-product formation.

13VUNA Final Report 2015

Transferred charge [Ah]

Concentration [mg/L]

Dichlormethane mass [mg]

Ammonia-N

Nitrate-N

Organic

Substances

(COD)

2000

1500

1000

500

0.5

0.4

0.3

0.2

0.1

0.0

0510 15

Transferred charge [Ah]

0510 15

Total

Urine

Off-gas

electrochemically. Thirdly, a metallic magnesium electrode was dis-

solved using electrolysis in order to fine-tune the struvite precipi-

tation process (Struvite Precipitation, p. 14). At a constant electric

potential, the electrode dosed the exact amount of magnesium

needed by the process. In addition to the positive effects of these

three applications, we also investigated their potential drawbacks,

e.g. the production of harmful chlorination by-products.

Remove and recover nutrients

Our laboratory experiments showed that ammonia and organic

substances can be removed rapidly. Using BDD or IrO2 electrodes

(Key figures), we achieved fast degradation by applying high volt-

ages. This approach could also be used to sanitise urine. The draw-

backs, however, were high energy consumption and the formation

of large amounts of chlorination by-products. Conversely, graphite

electrodes were able to remove ammonia at low voltages. The bene-

fits of this process were low electrode costs, reduced energy de-

mand, and no chlorination by-products. However, ammonia removal

was slow. Graphite electrodes were also successful in stabilising

nitrification. Electrochemical nitrite oxidation allowed high nitrite

concentrations to be brought well below inhibitory levels for nitri-

fying bacteria. Last but not least, electrochemical dissolution of

magnesium for struvite precipitation proved to be a process which

can be used to dose magnesium.

The future of urine treatment?

Electrolysis can offer a number of advantageous processes for the

decentralised treatment of urine, but the process must carefully

match the specific purpose. The most promising applications work

in combination with other technologies, such as the biological deg-

radation of organic substances or nitrification. However, there is still

substantial room for improvement in electrolysis for urine treat-

ment. For example, the transport of the reactants to the electrode

surface could be accelerated by optimising the hydraulic conditions

in electrolysis cells. Furthermore, current developments in material

science hold the promise of new electrodes, which will be able to

enhance specific chemical processes more effectively. Both these

developments – improved transport of reactants and specialised

electrodes – would reduce energy consumption during urine treat-

ment and the production of unwanted by-products.

Figure 2: Iridium dioxide (IrO2) electrodes remove ammonia and organic

substances (A), but can also produce harmful chlorination by-products, e.g.

dichloromethane (B).

Figure 3: Scanning electron microscope image of an iridium oxide electrode.

The surface has a texture comparable to cracked dried mud.

Figure 4: Off-gas from the electrolysis cell bubbles through the wash column,

where chlorination by-products dissolve in an organic solvent.

Key figures

Iridium dioxide Boron-doped diamond Graphite

Maximum daily organic substance removal (expressed as COD) g/m2 670 1 300 None

Maximum daily nitrogen removal g/m2 460 170 3

Energy consumption (per gram degraded nitrogen) Wh/g 82 160 42

Current efficiency of nitrogen removal % 21 14 33

14 VUNA Final Report 2015

• Struvite can be recovered from stored urine and used

as a solid phosphorus fertiliser.

• The process can be operated manually, e.g. in areas

without an electricity supply.

• The process can be automated to allow efficient

magnesium dosage.

• Magnesium dosage was controlled using turbidity or

electrical conductivity signals.

• Efficient retention of solids determines the overall

struvite recovery rate.

Urine Treatment Processes

Struvite Precipitation

A Solid Phosphorus Fertiliser from Urine

Conductivity [mS/cm]

Time [seconds]

Turbidity [NTU]

0100 200300 400500 600

Nominal

end-point

100

200

300

400

500

600

700

29.6

29.8

30.0

30.2

Measured

NTU

Model

NTU

Conductivity Conductivity

Figure 1: Measured and modelled turbidity and electrical conductivity

readings indicate when struvite precipitation ceases and allow precise

magnesium dosage.

Producing a phosphorus fertiliser from urine

Precipitation of struvite (Mg NH

·6 H

O) is a well-known

process for recovering phosphorus from urine. The precipitation

process produces solid struvite from the urine solution during a

chemical reaction. The reaction is initiated by adding a soluble mag-

nesium source (e.g. magnesium salts such as magnesium chloride

or magnesium oxide, or a waste product like bittern), and nearly all

the phosphorus can be precipitated from stored urine. Although

struvite also contains ammonia, its precipitation is predominantly

a phosphorus recovery process because less than 4 % of the am-

monia in urine is recovered. After the addition of magnesium, stru-

vite crystals form quickly, and only slight over-dosages are required

for complete precipitation of all the phosphorus. The final struvite

recovery rate is dependent on how efficiently filtration separates

the solids from the liquid. Slow filtration and clogged filters are

frequent problems in practical applications, as is the application

of the correct dosage of magnesium if the phosphorus concentra-

tion in the urine is unknown.

Two different setups

Eawag initially designed and developed a manually operated struvite

precipitation plant for Nepal (www.eawag.ch/stun). In eThekwini, a

40 litre plant was installed at the Newlands-Mashu field site and

tested for its ease-of-use and ability to process large volumes of

urine. The magnesium dose required was determined using an

estimation of the typical phosphorus concentration in local urine.

Filter bags were used to separate the struvite crystals, which were

then dried in ambient air for one to two weeks. A novel, automated,

A manually operated struvite precipitation plant at the Newlands-Mashu Field Test Site.

15VUNA Final Report 2015

Figure 3: Producing struvite at the field test site in eThekwini.

50 litre plant was developed and tested in the Pollution Research

Group’s laboratories at the University of KwaZulu-Natal. This plant

was operated using a process logic controller with software algo-

rithms, and magnesium was dosed according to the changes in real-

time sensor signals of either electrical conductivity or turbidity. Once

precipitation was complete, the struvite crystals were recovered in

a filtration module containing a cotton fibre disc. The operation of the

automated plant was compared with results of a computer model.

The manual and automated plants were both fed with urine collected

in urine-diverting toilets in peri-urban eThekwini.

A process that performs in the field

Municipal staff adopted the manual process with ease due to its

user-friendliness and the high volumes of urine that could be treat-

ed: trained operators could process up to 30 batches (40 litres each)

per day. However, simply using typical phosphorus concentrations

as a dosing strategy resulted in 30 % more magnesium being used.

Experiments using the automated process showed that turbidity

measurements were more sensitive than those using electrical

conductivity: the turbidity signal doubled between the start and the

end of magnesium dosage, while the electrical conductivity signal

only changed by 1 to 2 %. However, electrical conductivity did allow

a more exact determination of when struvite precipitation ceased.

Stepwise dosing proved to be a promising strategy for future fully-

automated plants. When adding the magnesium solution intermit-

tently, instead of continuously, the point when struvite precipitation

ceases can be determined more accurately using turbidity and elec-

trical conductivity measurements, however the control algorithms

are more challenging.

Easy-to-use technology

Overall, struvite precipitation using a manually controlled plant

holds the promise for use in remote areas: the process requires no

electricity, and operation can be learnt quickly by unskilled staff.

The process is labour-intensive, however, and tends to be ineffi-

cient due to imprecise dosing of magnesium. Our studies showed

that automation and sensor-controlled magnesium dosage can be

used to build more efficient plants, but this would also require elec-

tricity and staff having a greater understanding of the process. Fur-

thermore, the filtration of the struvite crystals remains challenging.

Agricultural trials showed that struvite precipitated from stored

urine performs as well as synthetic fertilisers (Fertiliser Trials, p. 22).

However, struvite precipitation is a process for phosphorus recov-

ery only. Further treatment is required to remove the other nutri-

ents that remain in the effluent. Importantly, struvite (and the

effluent) still contains infectious pathogens that are only partly

eliminated while drying (Inactivating Pathogens, p. 20).

Figure 2: The automated struvite precipitation plant at the Pollution Research

Group’s laboratory (UKZN) doses the exact amount of magnesium and urine.

Key figures

Maximum phosphorus recovery efficiency

(automated process) 93 %

Nitrogen recovery efficiency < 4%

Recommended magnesium dosage 0.86 g Mg /g P

(1.1 mol Mg /mol P)

Processing time for one batch

(manual reactor, without drying) 50 min

16 VUNA Final Report 2015

• Accumulation of the intermediate chemical, nitrite, can

lead to complete process failure.

• Nitrite measurement methods are being developed as no

suitable nitrite detector is yet available.

• Nitrite concentrations can be estimated indirectly using

dissolved oxygen concentrations and pH.

• Nitrite concentrations can also be estimated by

measuring the absorbance of ultraviolet light.

• New sensors will help to further automate urine

treatment processes.

Urine Treatment Processes

Process Control

Stabilised Control of the Nitrification Process

40 60 80 10 0120 140160 18

100

120

140

160

180

200

edicted nitrite concentratio

[mg NO2−N/L]

−

No ﬁltration, no dilution

Measured nitrite concentration [mg NO2−N/L]

−

Nitrite: the key variable for a stable process

Urine nitrification (Complete Nutrient Recovery, p. 6) is rather sen-

sitive to load disturbances. In an extreme case, this can stop the

system from functioning. This can happen if too much urine is add-

ed to the process or if there is a sudden increase of the concentra-

tion of ammonia in the influent urine. In the latter case, the balance

between the bacterial groups is disturbed and nitrite accumulates;

this results in an inhibition of the action of some of the crucial bac-

terial groups. To prevent a process breakdown, the nitrite increase

has to be detected within hours. This could in principle be achieved

using real-time measurement techniques, but there are currently

no commercial instruments available for this purpose. Two different

strategies were chosen to develop technologies for real-time nitrite

detection: first, an in-depth analysis of a measured ultraviolet (UV)

light spectrum, and second, combining measurements of pH and

dissolved oxygen using a dynamic computer model.

Ultraviolet light estimates nitrite

Commercial UV absorbance sensors are already used to detect

nitrite in combined sewer wastewaters, however, the concentrations

of nitrite, and interfering substances such as nitrate, are much

lower than in nitrified urine. For our tests, UV light adsorption was

measured through 0.5 mm samples of the treated urine using

wavelength steps of 1 nm. We used a mathematical tool (Principal

Component Regression) to extract and combine information about

the nitrite concentrations given by each wavelength. Different urine

concentrations were tested over four months of experimental work.

Emphasis was placed on the influence of suspended particles

and nitrate levels: particles disrupt the measurement of light, and

nitrate adsorbs light at similar wavelengths to nitrite. By carefully

Figure 1: Demonstration of nitrite estimation based on ultraviolet light

absorbance measurements. Predicted nitrite concentrations are shown as

a function of measured reference nitrite concentrations.

Specific substances in urine absorb ultraviolet light. This can be measured with a spectrophotometric probe.

17VUNA Final Report 2015

Time [hours]

0246

−

Nitrite concentration [mg NO

2−N/L]

Actual

concentration

Estimated

concentration

3−σ conﬁdence

limits

tuning the parameters of the Principal Component Regression anal-

ysis, we developed a model providing a reliable prediction of nitrite

levels, even in the presence of suspended particles and high con-

centrations of nitrate (Figure 1).

Using pH and oxygen data to calculate

nitrite concentrations

In the second approach, we used data on dissolved oxygen levels

and pH to calculate nitrite concentrations. Sensors for dissolved

oxygen and pH have been successfully used in urine nitrification

plants, but they are not sensitive to nitrite. However, all three para-

meters – dissolved oxygen, pH, and nitrite – are influenced by the

chemical and microbial processes in urine, and by using a mathe-

matical tool (in this case, an Unscented Kalman Filter, UKF), nitrite

concentrations can be estimated by the measurement of the other

two parameters. A UKF was tested using data from a computer

model representing the processes in nitrified urine. Using a com-

puter model allows a significant number of scenarios to be tested;

doing the same with actual experiments would take months or

even years. The results confirmed that nitrite concentrations can

be estimated reliably using a UKF approach, and in the future this

method will be further developed using a more elaborate computer

model or real measurements (Figure 2).

Increasing performance with real-time sensors

Process control would benefit greatly from the continued develop-

ment of both types of sensor. Current UV sensors are expensive

and sensitive to clogging (e.g. by biofilms), and our software sen-

sor still needs to be validated using real experiments. However,

the results to date confirm that combining various real-time meas-

urements allows useful information to be extracted – information

which would not be exploitable if measurement series were used

separately. Using current setups, nitrite can only be measured via

grab samples, but this necessitates regular maintenance. Likewise,

today’s urine nitrification plants operate below their maximum

capacity in order to have a sufficiently long reaction time to prevent

the build-up of potentially process-stopping high nitrite concentra-

tions. Future real-time nitrite sensors will help to improve perfor-

mance because the process control limits will be expanded.

Real-time sensors will be especially helpful to shorten process

start-up times; they will also be essential elements to help run

processes at remote locations with minimal maintenance.

Figure 2: Demonstration of the Unscented Kalman Filter. Actual nitrite

concentration (full black line), estimated nitrite concentration (dotted blue

line), and 3-σ confidence limits as a function of time.

Figure 4: The nitrite concentration in urine can be estimated using an ultra-

violet spectral probe. Before we tested the probe on the urine nitrification

plant, we had to carefully calibrate it in the laboratory.

Figure 3: To precisely measure pH and dissolved oxygen, we had to evaluate

the sensors’ response to changing conditions. Based on the real-time meas-

urements, we were able to estimate the nitrite concentration in urine.

Key figures

Ultraviolet light measurements

Range 220 to 400 nm

Resolution 1 nm

Light path length 0.5 mm

Unscented Kalman Filter

Real-time measurements Dissolved oxygen measurement

pH measurement

Other parameters Gas flow rate

Urine loading rate

Urine influent composition

18 VUNA Final Report 2015

• The majority of pharmaceuticals excreted by the human

body pass through urine.

• Ideally, urine-derived fertilisers should have negligible

pharmaceutical content.

• Pharmaceuticals in urine are partly degraded during

urine nitrification.

• Pharmaceuticals in urine can be removed effectively by

adsorption onto activated carbon.

Risks of Using Urine

Removing Pharmaceuticals

How Urine Treatment Affects Pharmaceuticals

Figure 1: Detecting pharmaceuticals in source-separated urine.

Precautionary investigations

The majority of nutrients excreted by the human body – but also the

majority of pharmaceuticals excreted – pass through urine. Due to

the high prevalence of HIV infections in South Africa, particularly

high concentrations of pharmaceuticals are to be expected in the

urine collected in the eThekwini Municipality. The negative effects

of pharmaceuticals on ecosystems are known from natural waters

that receive high loads of wastewater. Separating and treating urine

is an efficient way of preventing adverse effects on aquatic environ-

ments. Previous studies have shown that pharmaceuticals can be

degraded in soil, but there are also reports of plants taking up cer-

tain pharmaceuticals. It is as yet unclear whether pharmaceuticals

have negative effects on plants, or whether they might even enter

the food chain, if treated urine is used as fertiliser. As a precaution,

we investigated the degradation of pharmaceuticals during urine

storage and biological treatment. As an additional urine treatment

step, we also tested adsorption to activated carbon for the removal

of pharmaceuticals.

We measured how a laboratory nitrification plant removes pharmaceuticals from urine.

19VUNA Final Report 2015

Figure 2: Measuring pharmaceuticals with solid phase extraction (SPE) cou-

pled to liquid chromatography with tandem mass spectrometry (LC/MS/MS).

Field data guide laboratory experiments

Samples from the central urine collection tanks in eThekwini were

measured for concentrations of common pharmaceuticals. Based

on the results and on data in the literature about pharmaceutical

usage in South Africa, Europe, and the USA, we selected a repre-

sentative group of eleven pharmaceuticals (see Key figures). Since

HIV infections are common in South Africa, the list contains sev-

eral anti-retroviral drugs and antibiotics that are used to treat HIV/

Aids and prevent infections. To determine how urine storage af-

fects pharmaceuticals, untreated urine was spiked with the selected

substances and stored in air-free conditions for up to 77 days. Ad-

ditionally, we ran the urine through a laboratory nitrification plant

(Nitrification, p. 8; Complete Nutrient Recovery, p. 6) and investi-

gated, using batch experiments, how biological urine treatment re-

moved pharmaceuticals. A final series of batch experiments was

carried out using spiked nitrified urine to measure the adsorption

of pharmaceuticals to powdered activated carbon.

Substances degrade differently

Air-free urine storage (anaerobic) did not remove any pharmaceuti-

cals except for the high blood pressure drug hydrochlorothiazide,

which was hydrolysed by 90 % within 50 days. Biological treatment

in the aerated nitrification plant was more successful, however. After

10 to 24 hours, atazanavir, clarithromycin, darunavir, and ritonavir had

been almost completely eliminated. On the other hand, atenolol, di-

clofenac, emtricitabine, hydrochlorothiazide, sulfamethoxazole, and

trimethoprim, were relatively persistent. Since the main purpose of

nitrification is to stabilise the nutrients in urine, the removal of phar-

maceuticals is a beneficial side effect of this process. If required, the

addition of powdered activated carbon (PAC) can adsorb pharmaceu-

ticals. With the addition of 200 mg/L PAC, more than 90 % (by weight)

of the remaining pharmaceuticals were removed. At the same time,

PAC removed no beneficial nutrients. The biological and PAC treat-

ments also reduced ecotoxicity (measured using the bacterial biolu-

minescence inhibition test) and estrogenic activity (YES Test).

Nice to have or need to have?

The results from the urine nitrification process are in line with those

from research reports on biological wastewater treatment: a rea-

sonable share of the pharmaceuticals is eliminated, but effluent

concentrations remain considerable and some compounds are

hardly affected. An additional treatment step can ensure that suffi-

ciently low pharmaceutical concentrations are achieved. One of the

advantages of adsorption to PAC is the lack of by-products, which

would have to be considered when using other processes, such as

ozonation or electrolysis. While near-complete removal of pharma-

ceuticals from urine-derived fertilisers would be desirable, it is

unclear whether the higher costs and process complexity can be

justified. Neither European nor South African legislation currently

provides limits for pharmaceuticals in fertilisers. Further research is

needed to determine the possible effects of pharmaceuticals from

urine-derived fertilisers on the environment and human health.

Key figures

Pharmaceuticals analysed Type of pharmaceuticals

Estimated half-life during

urine nitrification

Elimination using

200 mg/L PAC

Atazanavir Antiretroviral 40 min > 99 %

Atenolol Beta blocker: treats high blood pressure 14 h 98 %

Clarithromycin Antibiotic 80 min > 99 %

Darunavir Antiretroviral 7 h > 99 %

Diclofenac Analgesic: painkiller and anti-inflammatory > 48 h > 99 %

Emtricitabine Antiretroviral > 48 h 90 %

Hydrochlorothiazide Diuretic: promotes production of urine

and treats high blood pressure

> 48 h 97 %

Ritonavir Antiretroviral 45 min > 99 %

Sulfamethoxazole Antibiotic > 48 h 96 %

Trimethoprim Antibiotic > 48 h > 99 %

20 VUNA Final Report 2015

• Source-separated urine is cross-contaminated with

pathogens from faeces.

• Ammonia acts as a natural sanitiser during urine storage

and helps to inactivate many micro-organisms.

• Low moisture content is the main factor inactivating

pathogens in struvite fertilisers.

• Nitrification only inactivates certain pathogens; further

processing is required to fully sanitise the product.

Risks of Using Urine

Inactivating Pathogens

Inactivation during Urine Storage and Treatment

Figure 1: Evaluating the inactivation of bacteria using culture-based methods

such as a dry-plate petrifilm (left) during the production of struvite (right).

Source-separated urine is not sterile

Humans excrete most of the pathogens in their bodies via faeces

rather than urine. However, urine collected from urine-diverting toi-

lets is frequently contaminated with faeces and can, therefore, con-

tain pathogens (bacteria, viruses, helminths, and protozoa). Some

pathogens (e.g. Salmonella Typhi, Schistosoma Haematobium) are

also excreted in the urine of infected persons. Disease-causing path-

ogens in stored urine and fertiliser products could compromise the

safety of urine collection systems and the quality of their end prod-

ucts. In order to analyse one component of human health risks dur-

ing urine separation and collection, we identified pathogens in urine

samples taken from various urine storage tanks in the collection ar-

eas in eThekwini. Because of the widespread detection of human

viruses in the urine, and their potential persistence in stored urine,

we evaluated the influences of urine storage time and conditions on

the inactivation of viruses. We also investigated the extent of inacti-

vation or removal of pathogen surrogate organisms in urine treat-

ment processes, including struvite precipitation and nitrification.

Identifying pathogens by their genes

In addition to culture methods used to analyse heterotrophic and

faecal indicator bacteria, a method based on polymerase chain reac-

tion was used to identify specific pathogenic bacteria and viruses in

field samples. This detected pathogens such as human adenovirus,

rotavirus, and norovirus, which are difficult, and in some cases impos-

sible, to measure otherwise. We selected 19 target organisms to

evaluate the presence of a range of diarrhoea-causing pathogens that

could pose a health risk to urine collectors or end-users. Of the bac-

teria tested, the most frequently detected were Aeromonas spp.,

Clostridium perfringens, and Shigella spp. The helminth Ascaris lum-

bricoides has previously been shown to be prevalent in eThekwini.

Laboratory studies investigated the fate of total heterotrophic bacte-

ria, the virus ΦX174, and the helminth Ascaris suum during struvite

filtration and drying (Struvite Precipitation, p. 14). We also determined

the effectiveness of the nitrification process (Nitrification, p. 8) in re-

moving pathogen surrogates from urine by measuring the bacteria

Salmonella typhimurium and Enterococcus spp., and three types of

Pathogens originating from urine samples grow on culture media and can be counted under the microscope.

21VUNA Final Report 2015

Key figures Summary of inactivation during processes

√ complete

(√) partial/possible under certain conditions

– no inactivation

Pathogen Class Storage1 Struvite dr ying2 Nitrification Distillation3

Indicator organism or pathogen surrogate

Viruses

MS2, ΦX174, Qbeta (√) (√) – √

Bacteria

Enterococcus spp., Salmonella typhimurium (√) (√) (√) √

Helminth

Ascaris suum (√) (√) Not evaluated √

1 WHO recommends urine storage for ≥ 6 months at ≥ 20 ˚C prior to application. 2 Enhanced inactivation requires drying at ≥ 35 ˚C and low relative humidity.

3 Distillation fulfils pasteurisation requirements (≥ 70 °C for ≥ 30 min); inactivation not measured.

Figure 2: Analysing samples in Durban for the presence of human pathogens.

Figure 3: Studying how the nitrification reactor inactivates bacteria and viruses.

viruses. Based on the behaviour of these pathogen surrogate organ-

isms throughout the urine treatment process, we drew conclusions

on the most efficient means of inactivating pathogens.

Ammonia, drying, and heat inactivate pathogens

most effectively

Treating urine for pathogens begins during urine storage. Shortly af-

ter collection, the pH of urine rises due to urea hydrolysis, and the

concentration of ammonia – a known biocide against pathogenic

microorganisms – naturally rises. Under typical urine storage condi-

tions, ammonia effectively inactivates viruses by attacking the viral

genome. However, urine storage is usually too short to ensure that

pathogens are completely inactivated. Protective measures are thus

necessary to reduce the risk of infection during urine collection. The

urine treatment processes investigated in this project only partially

inactivate pathogens. Experiments on the struvite produced revealed

that the main cause of pathogen die-off is the decreasing moisture

content that occurs during struvite drying. The virus ΦX174 was

strongly affected by decreasing moisture contents, but inactivation

of the helminth Ascaris suum was considerably lower. In nitrification,

the two bacteria evaluated, and one of the three viruses, were inacti-

vated, but only to a lower extent given the relatively short duration of

the nitrification step. The other two viruses assessed were hardly af-

fected, suggesting that some human viruses are likely to survive the

nitrification treatment step. One highly effective treatment for patho-

gens, however, is distillation. Nitrified urine in the distiller is heated at

80 °C for at least half an hour (Distillation, p. 10), a temperature used

to pasteurise commercial food products for safe consumption.

Producing safe urine fertilisers

The major goals of this urine treatment system are to recover nutri-

ents for productive use as fertiliser and prevent environmental pol-

lution by uncontrolled nutrient discharges. The main criterion for

choosing a technology is, therefore, its performance in nutrient con-

version. However, it is also important to ensure that procedures are

hygienic, and fertilisers are safe to use. Our findings on pathogen in-

activation thus have an influence on the choice of an optimal process

set-up. Any process that involves handling human waste products

requires good hygiene practices and the use of personal protective

equipment. The distillation stage of VUNA’ s production process for

concentrated nutrient solution will inactivate pathogens in urine, but

precipitated struvite may need additional treatment to ensure com-

plete dryness prior to use. Based on this project’s work so far, the

potential health risks of urine collection and manual struvite produc-

tion are now being investigated quantitatively. Besides the risks of

pathogens to human health, an important environmental risk to con-

sider when choosing an appropriate nutrient recovery process

comes from the presence of micro-pollutants, such as pharmaceu-

tical residues, in the urine itself (Removing Pharmaceuticals, p. 18).

22 VUNA Final Report 2015

• Struvite and concentrated nitrified urine were compared

to chemical fertilisers in pot experiments.

• Struvite is mainly a phosphorus fertiliser.

• Concentrated nitrified urine contains a wide range of

nutrients, but mainly nitrogen.

• Struvite and concentrated nitrified urine are as effective

as commercial fertilisers.

• Future studies will have to test the fertilisers on a range

of different soil types and crops.

Agriculture

Fertiliser Trials

Greenhouse Trials with Struvite and Concentrated Nitrified Urine

Figure 1: Carefully adding urine-derived fertilisers to the soil in the green-

house pot trials.

Human urine is a source of nutrients

Phosphorus (P) and nitrogen (N) are the most essential nutrients for

growing crops. The low availability of nitrogen or phosphorus in soil

often leads to low crop yields. As the world’s easily extractable

phosphorus reserves are both limited and concentrated in only a

few countries, it is considered a potentially critical resource. Nitro-

gen fertilisers can be synthesised from nitrogen in the air; a process

accounting for approximately 1 % of the world’s energy consump-

tion. Fertiliser prices are therefore likely to continue to increase in

the future, which would amplify pressures on farmers. It is essen-

tial that scientists continue exploring alternative nutrient sources

such as human urine, which is rich in nutrients essential to plants:

In addition to nitrogen and phosphorus, it also contains potassium (K),

sulphur (S), and numerous micronutrients. The VUNA Project test-

ed two different technologies for extracting nutrients from urine:

struvite precipitation (Struvite Precipitation, p. 14) and nitrification

combined with distillation (Complete Nutrient Recovery, p. 6).

Evaluation of fertiliser performance

The two technologies tested in VUNA produced two fertilisers: a sol-

id phosphorus fertiliser (struvite) and concentrated nitrified urine

containing all the nutrients found in urine. The main nutrient in the

latter is nitrogen. We needed to evaluate how plants took up nitro-

gen and phosphorus from these two fertilisers. In order to precisely

compare the proportions of phosphorus and nitrogen that plants as-

similate from either the fertilisers applied or from the soil, we pre-

pared the fertilisers using synthetic urine solutions containing

isotopic tracers. These isotopic labels do not affect plant growth,

but researchers can detect them in the plants. The results were

The greenhouse guarantees well-controlled conditions for fertiliser trials.

Peter Klaunzer

23VUNA Final Report 2015

Key figures

Composition of struvite 6 % N, 13 % P, 10 % Mg

Composition of the nitrified urine

solid used in this study 21 % N, 1.7 % P, 7.0 % K

Phosphorus applied as struvite and

recovered in plants 26 %

Nitrogen applied as concentrated

nitrified urine and recovered in plants 72 %

100

150

250

350

200

300

Plant N uptake [mg/kg soil]

Plants receiving chemical N (NH4NO3)Plants receiving SNUF

Total N uptakeTotal N uptakeFrom SNUFFrom NH4NO3

Plant P uptake [mg/kg soil]

Plants receiving chemical P (KH2PO4)Plants receiving Struvite

Total P uptakeTotal P uptake From StruviteFrom KH2PO4

Figure 2: Plants took up struvite and a commercial chemical phosphorus ferti-

liser (KH2PO4) in equal amounts.

Figure 3: Plants recovered equivalent amounts of nitrogen from the concen-

trated nitrified urine and from the reference, water-soluble, NH4NO3 fertiliser.

compared with commercially available chemical fertilisers. To en-

sure that the ratio of nitrogen to phosphorus was the same in each

fertiliser, struvite was complemented with synthetic ammonium

nitrate and the concentrated nitrified urine was complemented

with potassium phosphate.

Plant nutrient uptake

We grew ryegrass plants in separate pots in a climate-controlled

greenhouse. Before and after sowing the ryegrass, the pots were

fertilised with either struvite, concentrated nitrified urine, or water-

soluble commercial chemical fertiliser. Plants grown using the stru-

vite fertiliser took up similar amounts of phosphorus (Figure 2) to

plants grown using a commercial chemical phosphorus fertiliser

(26 % and 28 % of applied phosphorus, respectively). Plants grown

using the concentrated nitrified urine fertiliser took up 72 % of the

nitrogen applied, which was very similar to the 77 % taken up from

the commercial chemical fertiliser (Figure 3). About 26 % of the

phosphorus included in the concentrated nitrified urine was also

available to the plants, which was a similar ratio to the struvite and

chemical phosphorus fertilisers.

Effective urine fertilisers

This plant growth study demonstrated that under specific growing

conditions, urine-based fertilisers performed just as well as refer-

ence commercial chemical fertilisers. The promising results ob-

tained by both the VUNA fertilisers suggest that struvite and

concentrated nitrified urine could become valuable alternatives to

commercial plant fertilisers. The results obtained using struvite

were also confirmed by the Crop Science Department at the Uni-

versity of KwaZulu-Natal, which has likewise investigated plant

growth using struvite produced from real human urine. The experi-

ments at ETHZ were conducted using ryegrass and one type of soil

(acidic soil with pH 5.4 in water). In order to get a broader per-

spective of how effective our two urine-based fertilisers are, future

studies will involve testing them on a wide range of soil types and a

variety of crops. Due to the variety of nutrients it contains, concen-

trated nitrified urine may also be a good fertiliser for ornamental

plants indoors or in gardens.

Figure 5: The VUNA fertilisers – struvite and concentrated nitrified urine –

were both tested in greenhouse pot trials in Switzerland and South Africa.

Isotope

labelled

fertilisers

33P

N/P

15N 15 N

Soil N/P

N/P

from

fertiliser

N/P

from

soil

Total N/P uptake

by plant

Figure 4: Isotopic tracers retrace the origin of nutrients in a plant: 15

N and

P originate from the labelled fertiliser, whereas unlabelled N and P origi-

nate from the soil.

24 VUNA Final Report 2015

• A urine collection network was established in

peri-urban eThekwini.

• In a pilot study, urine was collected from 700 urine-

diverting toilets.

• Facilitators ensured good communication between the

local community, the Municipality, and researchers.

• Hiring staff in the community created jobs, and their

local knowledge improved collection rates.

• Good communication and awareness raising are as

important as optimised logistics.

Urine Collection Networks

Optimising Urine Collection

Minimising Cost and Maximising Yield

Figure 1: Municipal workers connect a 20-litre urine tank to the urine-

separation pipe at a household toilet in eThekwini.

Providing urine for the VUNA Project

Before the start of the VUNA Project, the urine from urine-diverting

toilets in eThekwini was not collected but was left to infiltrate into

the ground. To provide urine for our research on urine treatment

(Complete Nutrient Recovery, p. 6; Struvite Precipitation, p. 14), a

urine collection system had to first be established. This new system

formed part of the research on how incentives affect the use of

urine-diverting toilets (Incentives for Urine Production, p. 32). Two

types of collection areas were established: firstly, control areas, in

which the Municipality organised urine collection from the toilets

and transportation to the laboratories at the University of KwaZulu-

Natal and the Newlands-Mashu Field Test Site; secondly, treatment

areas, in which toilet users received incentives to carry their urine

to local collection tanks, from where the Municipality collected it.

In order to set up a urine collection system, the requirements and

constraints of several stakeholder groups had to be considered:

research teams and local facilitator, local communities and their

leaders, and municipal staff.

Urine collectors transfer urine from a jerry can into the collection tank on their truck.

25VUNA Final Report 2015

0102030 km

7 035

UDDTs

11 827

UDDTs

12 687

UDDTs

1976 UDDTs

4 964 UDDTs

1324 UDDTs

5 323

UDDTs

1 UDDT

451 UDDTs

Southern WWTW

Umkomaas

WWTW

Hammersdale WWTW

KwaMashu WWTW

Durban

WWTW catchment area

Treatment positioning

options

Position of WWTW

(center)

0 − 10 km radius

10 − 25 km radius

25+ km radius

Decentral treatment at

existing small WWTW

Central treatment at

existing larger WWTW

Central treatment at

existing large WWTW

Figure 2: The urine collection areas and treatment sites in eThekwini.

Figure 3: Rural settlement: Houses in rural eThekwini are scattered, making

access for urine collectors difficult.

Setting up urine collection areas

Several areas were chosen for urine collection, each with approxi-

mately 100 contributing urine-diverting toilets. Technical and social

criteria were used to decide whether an area was suitable for urine

collection: the number and density of toilets had to be sufficiently

high, cell phone reception had to be good, and the risk of violence

and riots had to be low. Before installing the collection tanks, both

the local political representatives (councillors) and the households

owning the toilets had to agree to the establishment of a collection

system. Facilitators were hired to ensure good communication be-

tween the local community and the Municipality. Each urine collec-

tion team consisted of two workers. They picked up the urine from

the urine-diverting toilets and carried it to a municipal truck that

transported the urine to the large collection tanks at either the

Newlands-Mashu Field Test Site or the University of KwaZulu-Natal.

Urine was collected once every two weeks.

Experiences in local communities

Urine was eventually collected from 700 toilets. Several toilets had

to be refurbished before urine tanks could be installed. Twenty-litre

jerry cans proved to be the optimal tanks to use at the urine-diverting

toilets because overflow was low and the tanks could be carried eas-

ily. Labelling the tanks with “urine” in isiZulu helped to reduce losses

through misuse or theft. Direct contact with the head of the house-

hold, but also with the other household members, was essential to

ensure the household’s involvement and support in the urine collec-

tion scheme. In order to ensure good communication and to raise

awareness, both the facilitators and the urine collection teams had

to be knowledgeable about the project’s background and goals. Hiring

urine collectors locally not only provided jobs in local communities

but also made collection more efficient: local collectors knew the

fastest ways to the toilets and remembered them, as well as which

tanks filled up fastest and which ones had been emptied recently.

Lessons for scaling-up

Based on these experiences in the field and the results of other

VUNA studies (Performance Modelling, p. 26; Incentives for Urine

Production, p. 32), the urine collection system is currently being fur-

ther optimised. In one project, the logistics of urine collection are

studied and optimised with the help of modern technical tools:

smart phones (instead of spreadsheets) are used for reliable data

collection, and GPS signals are recorded to learn more about collec-

tion routes. However, improving technical aspects is not sufficient

to set up an efficient urine collection system. Care must be taken to

establish a direct, personal contact between the Municipality, local

stakeholders, and households. This can only be achieved if the local

facilitators and urine collectors are chosen carefully. Last, but not

least, urine collection is also strongly influenced by external factors.

Civil unrest and bad weather can obstruct access to the urine collec-

tion areas for many days at a time.

Key figures

Average number of households

per pilot study area 100

Typical household tank size for

urine-diverting toilets 20 litres

Typical tank size on the

collection truck 500 to 1 000 litres

Urine collection team size 1 driver from the Municipality,

2 collectors, 1 local facilitator

Maximum volume collected per

week during the pilot study 1 500 litres

Average daily travel distance of

one collection truck 200 to 300 km

26 VUNA Final Report 2015

• Cost-effective urine collection from scattered tanks

requires a well-organised procedure.

• The model developed, DeSaM, allows the comparison

of alternative urine collection setups.

• DeSaM uses a modular structure and statistical

assumptions to quantify performance.

• Large urine tanks at urine-diverting toilets and

“on demand” collection lower costs effectively.

• Different collection schemes are optimal for maximising

revenue and minimising pollution by overflows.

Urine Collection Networks

Performance Modelling

Computer Simulations Help to Optimise Urine Collection

Figure 1: The Decentralised Sanitation Product Management Model (DeSaM)

is used to describe the real situation in eThekwini in a simplified way (A).

It allows us to consider every urine collection tank as an individual module

that may be affected by random events (B).

Challenging collection

A waterless sanitation system, such as the urine-diverting toilets in

eThekwini, does not require an expensive sewer network; it can be

implemented on demand whenever funds are available. However,

if in-situ urine use is not possible, other methods of collection need

to be investigated. Our experience has shown (Optimising Urine

Collection, p. 24) that, in order to minimise costs, urine collection

must be well managed. Developing an optimal strategy for urine

collection is a demanding task: there are thousands of toilets, each

with different properties such as number of users, usage patterns,

distance from the street, or the state of repair. Numerous different

resources also have to be managed wisely, such as the number of

municipal workers involved, working hours, and whether to use rov-

ing urine collection trucks or urine tanks at collection points. Finally,

the collection strategy has to be chosen based on the overall per-

formance goal, which could be maximising revenue per litre of

Density of toilets strongly influences the collection team’s driving distance, and thus the collection costs.

27VUNA Final Report 2015

Figure 3: The computer model analyses how different parameters, e.g. household

size, toilet usage frequency, or breakdowns, affect the urine volume collected.

Figure 2: A) The initial design for toilet tanks (4 L capacity) is not sufficient (orange); the performance is improved by increasing the toilet tank capacity to 40 L

(green). B) A bigger vehicle tank (green) and an optimised collection route (servicing the fullest tanks first; blue) bring further improvement. C) Decentralising

the collection by employing local collectors can help to reduce costs (red). The dotted lines with the shaded areas mark the 10 % and 90 % confidence intervals.

Number of workdays per week

Costs per workday: less than € 60

ABC

Max. collectable urine (DeSaM)

Mean result for 40 L toilet tanks

Mean result for 4 L toilet tanks

Mean result for 40 L toilet tanks

Mean result for optimised tour (40 L)

Mean result for optimised collection

Number of workdays per week

Costs per workday: € 100

Urine collected per

week [L]

Number of workdays per week

Costs per workday: € 112

15432

1000

4000

3000

2000

154321 5432

urine, minimising environmental pollution by urine overflows, or

providing an optimal service for the toilet users.

From centralised to decentralised

The Decentralised Sanitation Product Management Model (DeSaM)

was developed to compare different management approaches. The

model’s high flexibility is based on the following principles. Firstly, its

basic building blocks are tanks with varying properties, such as urine

inflows and outflows; and whether they are stationary (e.g. at a toilet)

or mobile (e.g. on a collection vehicle). Secondly, statistical distribu-

tions are used to simulate known variables (e.g. the number of users

per toilet) or to express uncertainties such as toilet usage by a single

person. Thirdly, the model is dynamic, because it considers time de-

pendent events such as urine pick-up. This structure allows the model

to simulate a wide range of urine collection setups (or even other

waste streams). We focused mainly on the following two setups:

firstly, a fully centralised setup (municipal collection) with municipal

staff collecting urine and bringing it to a central treatment facility;

and secondly, a semi-decentralised setup (local collection) with local

workers bringing urine to large intermediate storage tanks, which are

then emptied by municipal staff. The data on costs (e.g. salaries,

transport times) were based on our own research in eThekwini.

More volume

A key element in reducing costs and environmental impact is the lo-

cal tank at the urine-diverting toilet. Increasing the tank size reduces

the cost per litre of urine collected considerably. The optimal size

was found to be 40 litres, e.g. made up in the in form of two 20-litres

jerry cans. Using larger transport tanks on the trucks, however, has

little effect on the overall volume of collected urine but adds to the

costs per litre of urine. Increasing the number of visits by the collec-

tion staff has a similar effect. Another effective way to reduce costs

substantially is to optimise the order of collections. Collecting the

fullest tanks first (collection on demand) is optimal and brings large

efficiency gains. This strategy requires sensors, notification by the

toilet users, or local workers who acquire experience on filling rates.

The simulations also revealed that if mean values were assumed

instead of statistical distributions, and constant conditions were

assumed instead of time dependency, then urine overflows were

substantially underestimated.

Model assesses scenarios based on goals

This study confirmed that optimising urine collection is a challenging

task: not all the influences on the system can be described in detail,

and the interdependency of the different elements can have a strong

effect on the overall performance. Additionally, the final decision on

the optimal collection scheme depends on the overall performance

goal. A computer model like DeSaM allows us to identify the most

critical elements and assess the effects caused by changes to parts

of the system. This type of model is especially valuable as a decision

support tool for the design of an appropriate collection scheme, as

different options can be tested easily and inexpensively. Since urine

collection is one of the main cost factors in transforming urine into

fertiliser (Business Model, p. 34), a computer model such as DeSaM

can be a decisive tool for setting up a sanitation system relying on a

collection scheme. DeSaM can also be used as a cheap alternative

to preliminary field studies for testing novel collection setups.

Key figures

Model use

Software costs 0 ZAR (freeware)

Simulation time for one scenario 2 seconds

For the urine collection situation in eThekwini we assessed

Minimum required capacity

of a toilet tank approximately 40 litres

Minimum cost of collecting

1 litre of urine < 0.8 ZAR (< 0.06 EUR)

28 VUNA Final Report 2015

• Satisfaction with urine-diverting toilets increased

between 2011 and 2014.

• Odour remained a dominant concern in 2014.

• In 2014, urine-diverting toilet users continued to aspire

to have flush toilets.

• Respondents largely support an official (municipal)

vault clearing service.

Social and Economic Aspects

Social Acceptance

The Evolving Results on Toilet Acceptance

Figure 1: Some users converted their urine-diverting toilet to a flush toilet.

Why study social acceptance?

In 2002, the eThekwini Municipality initiated a programme to imple-

ment dry sanitation on a large scale. This occurred after the municipal

boundaries had been expanded to include an additional 75 000 house-

holds, 80 % of which were without appropriate sanitation services.

The Municipality embarked on a project to provide urine-diverting

toilets and yard tanks to all households in unserviced areas. To date,

approximately 82 000 urine-diverting toilets have been installed. In

2011, the Municipality commissioned a study to explore the social

acceptance of urine-diverting toilets. The main focuses of the study

were user satisfaction, possible problems with the toilet after its con-

struction, the measures needed to ensure the sustainability of urine-

diverting sanitation, and the need for municipal services such as

emptying faeces vaults. In 2014, we repeated that assessment (with

a smaller sample size) in order to identify any changes over time.

How social acceptance was assessed

In 2011, we developed a structured questionnaire and, using mobile

phone technology, we interviewed 17 500 householders in 65 areas

of eThekwini. Considering the large sample size, mobile phones of-

fered a more efficient approach than pen and paper, allowed better

control of data quality, and immediate digital data capture. In the

second survey, in 2014, we interviewed 1 500 householders in five ar-

eas of eThekwini (two more rural areas and three more urban areas).

Both surveys comprised direct questions to the householder as well

as an observational checklist completed by trained fieldworkers. Ad-

ditional questions in the second survey assessed perceptions of a

municipal vault-clearing service, usage of the urinal and the children’s

toilet seat, and investigated perceptions of previous educational cam-

paigns. The smaller sample size allowed for a pen and paper survey,

which we captured digitally on completion of the fieldwork.

Community members describe how they perceive the urine-diverting toilets.

29VUNA Final Report 2015

Figure 2: Respondents’ satisfaction with urine-diverting toilets increased

from 2011 (left) to 2014 (right). (2011: n = 17 449; 2014: n = 1 567)

Very satisﬁed 7% No response 1% Very satisﬁed 6%

Satisﬁed

23%

Not satisﬁed

70%

Not satisﬁed

59%

Satisﬁed

34%

Acceptance and key issues

We found that the percentage of respondents who were satisfied

or very satisfied with their urine-diverting toilets increased from

30 % in 2011 to 40 % in 2014. This was a key result. In 2011, users

complained most about odour (27 %), the toilet door not closing

(22 %), and poor construction (12 %). In 2014, their complaints were

odour (26 %), the condition of the door (15 %), and the faecal vault

not being cleared (14 %). The 2014 survey asked toilet users what

they thought about an organised vault emptying service, and 80 %

of respondents supported this idea. Of the people surveyed 59 %

would be satisfied by having the vault contents taken offsite, while

26 % would be satisfied having it buried onsite. All five areas indi-

cated greater levels of acceptance for an official municipal emptying

service rather than community vault-emptying teams. Since the first

survey, there had been a clear decrease in households receiving in-

formation on urine-diverting toilets (from 90 % to 66 %, respectively).

Only 50 % of the 2014 respondents stated that they had personally

received information, and 36 % of respondents found this useful.

Targeting better acceptance

Survey results have guided – and continue to guide – the manage-

ment of urine-diverting toilets in eThekwini. The fact that toilet users

would welcome a vault clearing service, and would prefer that the

contents be removed offsite, is considered positive in light of eThek-

wini Municipality’s present plans for nutrient collection and reuse.

The support for vault emptying is especially strong in more urban

areas. Addressing user satisfaction is vital for the next stage in the

development of sanitation systems aimed at recovering nutrients.

Results from the 2014 survey suggest that there has been a de-

crease in the proportion of respondents who have been educated

about toilet usage and maintenance. With well targeted and de-

signed educational activities, we may yet be able to overcome the

remaining negative perceptions and barriers in relation to collecting

and reusing excreta (Campaigning for Health and Hygiene, p. 30).

Figure 3: Over the years, the eThekwini Municipality has constantly improved

the toilet design to make it more robust, durable, and easy to install.

Figure 4: Some users were not satisfied with their urine-diverting toilet, be-

cause the doors were stolen or damaged, or the vent pipes were dysfunctional.

Key figures

2011 2014

Respondents satisfied or very satisfied

with their urine-diverting toilet 30 % 40 %

Respondents who maintain a pit latrine

in addition to their urine-diverting toilet 14 % 17 %

Respondents who had received

education on toilet usage 90 % 66 %

Complaints of smell 27 % 26 %

Respondents in support of a vault

clearing service 80 %

• in the more rural areas 77 %

• in the more urban areas 82 %

30 VUNA Final Report 2015

Health and hygiene education meets sanitation

One of South Africa’s development priorities is the provision of safe

water and proper sanitation to its entire population. In the past, san-

itation was seen mainly as a technical issue that included building

toilets. However, toilets are not the only factor in the provision of

good sanitation. Indeed, in order to break the cycle of sanitation-re-

lated disease, all the factors affecting sanitation must be addressed.

It has become increasingly clear that social considerations are a vi-

tal part of the battle. Throughout the health and hygiene education

campaign carried out in eThekwini, we explored how awareness

promotes the acceptance, usage, and maintenance of urine-divert-

ing toilets. Health and hygiene education is mostly about changing

people’s behaviour through raising awareness. We assume that

everybody would like to be healthy and clean and that people who

know about good hygiene also practice good hygiene. Awareness

can be raised using different means of communication, for exam-

ple, entertainment, education, or printed materials.

Developing a campaign using toilet users’ own words

We aimed to study and understand how toilet users perceive toilets

and hygiene. Our survey collected qualitative data through a process

of data triangulation, using desktop analysis, in-depth interviews, and

focus group discussions in three rural areas: Zwelibomvu, Lower

Maphephetheni, and Hlanzeni. We probed participants’ answers to

elaborate and clarify the matters being discussed. All the interviews

and focus group discussions were recorded and transcribed word for

word in isiZulu, and were then translated into English. Our work was

guided by a symbolic interactionism approach, a process by which

meanings for individuals are formed through the interactions be-

tween individuals in a society. Categories were developed from these

findings and were later coded to themes. People’s perceptions and

reported behaviours concerning toilets and hygiene formed the ba-

• Many households still do not completely approve of

urine-diverting toilets.

• Health and hygiene education enhances proper toilet

use and maintenance.

• The community appreciated the educational material

developed by the Municipality.

•

The feedback from the community shapes the

education campaign.

Social and Economic Aspects

Campaigning for Health and Hygiene

Improving Health and Hygiene Education in eThekwini

Figure 1: EWS facilitators and household members discuss whether the

urine-diverting toilet is a permanent asset to the household.

School children learn about the health and hygiene aspects of urine-diverting toilets.

31VUNA Final Report 2015

Two vaults above

ground, for faeces

collection and

storage.

Two vent pipes are

provi ded to ventila te the

faeces vault, remove odour

from t he room and to speed

up the drying process and

eliminate flie s.

A urine pipe

connecting the

pedestal and urinal

to the ur ine tank.

A urinal: is considerate

of the f act that in mos t

cultu res men pref er to

stan d when urinating

rath er than sitt ing or

squatting.

A bucket w ith

soil / ash to co ver

the fae ces after

defecating, so the

contents will break

down an d dry faste r.

Closed door

prevents flies

from spreading

diseases.

The pipe outlet

should b e sealed with

a mesh to trap flie s.

sis for developing educational materials comprising leaflets, posters,

a video, and workshops. These materials were presented in isiZulu

language, the first language in all the study areas. The final stage was

to test the educational materials in households, with community

members, and at schools.

Urine-diverting toilet users aspire for more

One hundred and twenty people participated in our focus group dis-

cussions, and 25 key informants had in-depth interviews. Participating

householders were grouped into categories based on the condition

of their toilet (see Table 1). Overall, 97 % of households actually used

their urine-diverting toilet. Of these, however, 80 % did not maintain

them properly, failing to repair broken items, for example. Most people

in this group reported not having received any education on toilet us-

age. The level of acceptance of urine-diverting toilets was very low.

Strikingly, more than 90 % reported that they did not regard them as

a permanent asset to their household: they aspired to have a flush

toilet. Findings also revealed that children took the leading role in toi-

let maintenance and that younger survey participants better accepted

the toilets as a permanent asset than older people. Findings further

revealed that toilets are not a topic of interest and conversation in the

community; people reported that they did not know how their neigh-

bours felt about their toilets or whether they maintained them.

Engaging education material for all ages

Educational materials were developed to address the surveys’ key

findings about water scarcity, the benefits of urine-diverting toilets,

the role and importance of each item in the toilet, the contamination

cycle, and hand washing. However, different modules were devel-

oped for different groups: households, communities, primary schools,

and high schools. A large proportion of the local inhabitants was re-

ceiving health and hygiene education for the first time. Focus group

discussion participants were shocked to learn about water scarcity

and the role that urine-diverting toilets were playing in saving water

and the environment: “I’m excited about this information. All people

need to know about this… you need to come again and again until

we all know and understand.” The fact that the campaign’s six facili-

tators were university graduates and had been well trained on the

modules contributed significantly to the successful roll out of this

health and hygiene education campaign. The final evaluation will be

carried out in the future as a separate project.

Figure 2: Educational material

shows the urine-diverting

toilet’s physical structure and

the importance of each item.

Key statements form toilet users

Preference “I am waiting for the Municipality to come and

change those urine-diverting to flush toi

lets.”

Focus Group Discussion (FGD) Participant

Role models “If it was such a good toilet then why is our

councillor not using it or even our president.”

FGD Participant

Happy with “We were given this toilet because there is

urine-diverting

no other suitable one for an area like this, so

toilets I have to be okay with it.”

FGD Facilitator

Unhappy with “Who wants to touch their own faeces really,

urine-diverting

we are human beings as well, we have feelings.”

toilets FGD Participant

Benefits “We were told about using the dried faecal

matter as manure, but not all of us have gardens.”

Ward Committee Member

Table 1: The study distinguished toilet maintainers, non-maintainers, and

non-users.

Category Explanation Percentage

Maintainers

The urine-diverting toilet is in good con-

dition: all items intact, e.g. door, vent

pipe. Broken items

are re

paired using

appropriate materials.

17 %

Non-maintainers The urine-diverting toilet is in bad con-

dition: it has broken items, and they ei-

ther remain unrepaired or are repaired

using inappropriate materials.

80 %

Non-users Households that have a urine-diverting

toilet but choose not to use it.

3 %

Glynn Erasmus, ERA design

32 VUNA Final Report 2015

• Current use of urine-diverting toilets is low.

• Financial incentives were provided for bringing urine

jerry cans to collection points.

• Cash payments were successful in increasing toilet use.

• Walking distance to collection points must be

minimised to foster participation.

• Cash transfers could not only be a tool for improving

sanitation but also for reducing poverty.

Social and Economic Aspects

Incentives for Urine Production

Cash Transfers to Increase Toilet Use

Figure 1: Exchanging urine for tokens. Toilet users received tokens according

to the volume of urine they delivered to the collection points during the pilot

study. Tokens could then be exchanged for cash.

Many toilets, few users

Conditional cash transfers – cash payments linked to some kind of

desired action or behaviour – have been successfully used to en-

courage school attendance, increase vaccination rates, and pro-

mote other similar, socially desirable behaviours. Prior to the VUNA

Project, they had not been tested for sanitation. In the areas we

studied, the majority of residents had access to a urine-diverting

toilet, but consistent use and proper maintenance were lacking. Toi-

let use and hygiene are usually promoted using educational cam-

paigns and health messages (Campaigning for Health and Hygiene,

p. 30), but these are not always effective or sustainable. We want-

ed to test whether offering incentives for collecting and transport-

ing urine to a collection point could encourage people to make

greater use of their toilets. Furthermore, we wanted to determine

whether incentivised collection would be a more cost-effective way

to collect large quantities of urine for nutrient recovery than institu-

tionalised collection (Optimising Urine Collection, p. 24).

Multi-phase data collection and field experiments

In order to determine the impact of cash transfers on the use of

urine-diverting toilets, we first had to establish to what extent they

were being used beforehand. Twenty-litre plastic tanks were in-

stalled on the outside of about 700 toilets in order to collect all the

urine produced. The volumes generated were measured three

times a week for a month in order to determine the daily average.

We also administered household questionnaires to better under-

stand family compositions, financial situations, and sanitation prac-

tices. Over approximately six months, we tested how households

responded to different pricing schemes in which cash was offered

in exchange for the urine to be collected and transported to a local

collection point. We wanted to see how many people participated,

how much urine they generated, and how these factors varied de-

Municipal employees pick up urine from a local collection tank, where incentives are distributed for urine.

33VUNA Final Report 2015

Figure 3: Encouraged by the incentives, a young toilet user delivers urine to

a collection centre.

0 L 20 L0 L 20 L

10 ZAR

20 ZAR

10 ZAR

20 ZAR

0.5 ZAR/L scale 10 ZAR ﬂat

1 ZAR/L scale

10 ZAR ﬂat+0.5 ZAR/L scale

Baseline Intervention

Urine Production [L/household-day]

0.5

1. 0

1. 5

2.0

2.5

0.0

0.5 ZAR scale 1 ZAR scale 10 ZAR ﬂat10 ZAR ﬂat +

0.5 ZAR scale

Control

Figure 2: The cash transfer was different in each of the four study areas (left), in order to investigate what amount was necessary to encourage toilet users

to collect and drop off their urine. Only the 1 - ZAR scale and the 10 - ZAR flat rate appeared to cause an increase in toilet use and urine production (right).

pending on the price and the distance that householders had to

walk to deliver their urine. After this experiment, we carried out an-

other household questionnaire in order to understand why people

did or did not participate.

Use is low, but can be increased

Based on medical data, an average household of six people should

produce at least 42 litres of urine a week. However, depending on

how many people go to school or work, the volume collected at

home would be somewhat less. Measurements before the incen-

tive experiment showed that only about 10 litres per week were be-

ing collected, which is far below the possible maximum. When a

small incentive of 0.5 ZAR per litre was offered, people did not pro-

duce more urine, and participation remained low. However, at the

higher urine price of 1 ZAR per litre, production increased by almost

7 litres per household per week, or an increase of about 70 % over

the initial level. People were effectively being compensated at

twice the minimum wage for a 1 hour round trip walk, if they deliv-

ered a full tank. About 74 % of households collected at least one

payment, while about 35 % of households participated weekly. Not

surprisingly, however, longer walking distances correlated with

lower participation and smaller volumes being delivered. We also

determined that there was no typical participant, i.e. poorer fami-

lies did not participate more than wealthier ones.

Willingness is a function of price

Measuring urine production at the household level was an easy, safe

way to estimate toilet use that could be used by future projects. We

were able to show that toilet use could be increased substantially

by offering conditional cash payments. Although not every house-

hold participated, we now understand how the price per litre and

programme implementation could be optimised to increase partici-

pation and toilet use. Although the incentive payments are costly,

they induce a positive change in behaviour, whereas institutionalised

collection likely does not have the same effect. In addition, the costs

associated with the incentives help create local employment, re-

duce transport costs for the Municipality, and put much-needed

cash into the hands of the very poor. Although this was a small

study, conditional cash transfers for sanitation programmes appear

to be a promising means of increasing toilet use, and over time they

could encourage the formation of a sustainable habit.

Key figures

Exchange rate at the time of publication: 1 EUR = 13 ZAR

Number of tanks where baseline urine production

was measured 700

Number of households benefiting from incentives 384

Maximum daily urine production rate per household 2.7 litres

Participants stating that incentives had a “big”

impact on their budgets 95 %

34 VUNA Final Report 2015

Key Partners

• Water &

Sanitation

Utility

• Local

Service

Providers

• Etc.

Cost Structure

• Investment

• Operation

• Incentives

Revenue streams

• Fees

• Sales of end products

Key Activities

• Collection

• Treatment

• Sales

Value

Proposition

• Reliable

and safe

emptying

• Quality

Fertiliser

• Distilled

Water

Customer Relations

• Regular collection

• Fertiliser sales

Marketing

• Value-added service

• Niche products

Customers

• Toilet

owners

• Public

• Farmers

• Etc.

Key Resources

• Urine

• Funds

• Personnel

Figure 2: The “Business Model Canvas” integrates the components of a

value chain from a business perspective.

Figure 1: The business model examined different urine collection scenarios at

various scales: A) twelve small decentralised urine treatment plants; B) two

medium centralised treatment plants; C) one large centralised treatment plant.

ABC

• The business model covers the value chain from urine

collection to the final fertiliser product.

• Urine treatment in a large plant is less expensive, but

transportation costs are higher.

• A concentrated liquid fertiliser can provide more revenue

than a solid bulk fertiliser.

• Besides fertiliser, distilled water is another potential

marketable product.

• Social, technical, and environmental boundaries also

have to be considered when choosing a system.

Social and Economic Aspects

Business Model

Investigating the Value Chain for Source-separated Urine

Value and nutrient flows

The VUNA Project aims to reduce the overall costs of sanitation by

recovering nutrients from urine and creating value from waste. To

estimate the potential financial benefits that could be generated

from source-separated urine, it is important to identify possible end

products, establish their value, and estimate the costs along the

value chain, such as those for the collection and treatment of urine,

or for marketing the final products. In order to better understand the

value chain, we analysed the various components of the nutrient

recovery system with a business perspective using the so-called

Business Model Canvas. The Canvas integrates components such as

resources and activities, key partners, and customer relationships;

it identifies the cost and revenue streams in the system. Based on

an overall picture of the market that one intends to enter, the meth-

odology also helps to explore potential market segments and to

define market expectations towards a product.

The business model examined the value chain from urine collection to the final fertiliser product.

35VUNA Final Report 2015

Urine

Production CollectionTransport Storag

torage Sales & Distr.Nitriﬁcation Distillation

Nitriﬁed UrineConcentrated Nutrient Solution

Figure 4: Putting a price tag on VUNA liquid fertiliser: The business model

compared fertiliser prices based on nutrient content, but also found out that

retail prices vary greatly regardless of nutrient content.

Figure 3: The VUNA value chain includes the nutrient recovery process from urine collection to the final fertiliser product. Urine collection and treatment at a

larger scale will provide a more reliable estimate of the exact costs.

From urine collection to the fertiliser market

In the case of VUNA, the value chain ranges from urine collection

at the household level to the sale of final fertiliser products. The re-

search on the business model initiated a new pilot study on urine

collection (Optimising Urine Collection, p. 24). This in turn incorpo-

rated findings from previous studies, but varied important parame-

ters of this institutionalised approach – the size of household urine

tanks and the frequency of collection by municipal workers. A sepa-

rate study looked at a scheme in which toilet users dropped off their

urine at collection centres (Incentives for Urine Production, p. 32).

For the treatment of urine, the business model study focussed on

the nitrification/distillation process, since this technology had proved

its worth at a pilot scale and is able to recover all the nutrients in

urine. Finally, the study evaluated the market potential for its final

product and the prices of existing fertilisers by discussing these is-

sues with fertiliser producers and sellers.

Plant size versus transport distance

On the cost side, urine collection has a high potential for further op-

timisation. During the pilot study involving 700 households, collec-

tion costs were as high as 4 000 ZAR per 1 000 litres of urine. Our

calculations estimated that costs could be as low as 820 ZAR per

1 000 litres in an optimised system. The cost of urine treatment can

be reduced by increasing the size of the treatment plants. Producing

concentrated urine fertiliser in one of the VUNA pilot plants (Com-

plete Nutrient Recovery, p. 6) cost about 1 900 ZAR per 1 000 litres

collected urine. In a large plant treating 120 000 litres of urine per

day (estimated daily volume from the 82 000 urine-diverting toilets

in eThekwini), costs could be as low as 91 ZAR per 1 000 litres. On

the revenue side, 1 000 litres of collected urine are worth 120 ZAR

based on bulk fertiliser prices for nitrogen, phosphorus and potas-

sium. However, specialised fertilisers such as flower fertiliser for

the home market can have retail prices up to 80 times higher for the

same amount of nitrogen, phosphorus, and potassium.

Integrating cost factors

The data from the business model indicated some general trends:

in the case of eThekwini, treatment and collection costs could be

reduced by approximately a factor of 20 compared to the costs of

the pilot studies. However, more experience needs to be gained in

optimising urine collection (Optimising Urine Collection, p. 24), and

a better understanding of the technical and environmental risks of

large urine treatment plants is required. On the revenue side, the

type of end product will strongly influence the sales price: if the

liquid fertiliser is sold based on bulk fertiliser prices, revenues will

be low. If maximum revenue is the goal, the fertiliser will have to

be marketed as a niche product, such as flower fertiliser. In addition

to fertiliser, distilled water (a by-product of urine treatment) can also

be sold to increase revenue. In order to make a final decision on the

exact urine management scheme, more factors will have to be con-

sidered: job creation, available expertise and technology, environ-

mental protection, and the possibility that the Municipality uses

the fertiliser for its own green areas.

Key figures

Estimated costs and prices per 1 000 litres of urine

Collection costs

(depending on scale and optimisation) 820 to 2 000 ZAR

Treatment costs

(depending on scale and optimisation) 91 to 1 900 ZAR

Net nutrient value

(based on bulk NPK fertilisers) 120 ZAR

Retail price

(depending on branding and product type) 120 to 10 000 ZAR

Key figures are under review and being developed further.

Elisabeth Real

36 VUNA Final Report 2015

Project Team

Partner Institutions

Eawag

Swiss Federal Institute of

Aquatic Science & Technology

EWS

eThekwini Water & Sanitation

UKZN

University of KwaZulu-Natal

ETHZ

Swiss Federal Institute

of Technology Zurich

EPFL

Swiss Federal Institute

of Technology Lausanne

Project Team

The VUNA Family 2010 – 2015

Funding Agencies

Bill & Melinda Gates Foundation (main donor)

Swiss National Science Foundation

United States National Science Foundation

Steering Committee

Tove A. Larsen (Eawag, Urban Water Management)

George Ekama (University of Cape Town)

Neil Macleod (EWS)

Chris Zurbrügg (Eawag, Sandec)

Principal Investigators

Kai M. Udert (Eawag, Process Engineering)

Teddy Gounden (EWS)

Project Coordination

Bastian Etter (Eawag)

Urine Treatment Processes

Complete Nutrient Recovery: Bastian Etter, Kai M. Udert,

Bettina Sterkele, Alexandra Fumasoli, Michael Wächter,

Mathias Mosberger (Eawag, Process Engineering);

Lungiswa Zuma, Mlungisi Mthembu (EWS); Maximilian Grau,

Sara Rhoton, Chris Buckley (UKZN, Pollution Research Group).

Nitrification: Alexandra Fumasoli, Kai M. Udert, Bettina Sterkele,

Eberhard Morgenroth, Alexandra Florin, Corine Uhlmann,

Gabriel Kämpf (Eawag, Process Engineering).

Distillation: Michael Wächter, Kai M. Udert, Bastian Etter,

Samuel Huber (Eawag, Process Engineering); Mischa Schwaninger,

Thomas Gmeinwieser (Swissi Process Safety).

The VUNA team gathering at the Newlands-Mashu Field Test Site.

37VUNA Final Report 2015

Contact Addresses

vuna@eawag.ch

Eawag – Swiss Federal Institute of

Aquatic Science and Technology

PO Box 611

8600 Dübendorf

Switzerland

EWS – eThekwini Water & Sanitation

PO Box 1038

4000 Durban

South Africa

UKZN – University of KwaZulu-Natal

Howard College Campus

4041 Durban

South Africa

>> For up to date contact information of individual

team members, visit www.vuna.ch.

Business Model: Heiko Gebauer (Eawag, Environmental Social

Sciences); Luzius Etter (University of St. Gallen);

Maximilian Grau (EWS).

Documentation

Susan Mercer (UKZN, Pollution Research Group);

Corine Uhlmann, Nina Gubser (Eawag, Process Engineering).

Laboratory

Merlien Reddy (UKZN, Pollution Research Group);

Sibongile Maqubela, Siobhan Jackson (EWS, Scientific Services);

Claudia Bänninger-Werffeli, Karin Rottermann

(Eawag, Process Engineering);

Falk Dorusch, Birgit Beck (Eawag, Environmental Chemistry).

Workshop

Kenneth Jack (UKZN, Pollution Research Group)

Richard Fankhauser, Andreas Raffainer (Eawag)

Administration

Ariane Eberhardt, Brigitte Pfister (Eawag, Process Engineering)

Kerry Philps (UKZN, Pollution Research Group)

Tracey Naylor (EWS)

Project Officers at the

Bill & Melinda Gates Foundation

Carl Hensman

Alyse Schrecongost

Acknowledgements

We thank all our sponsors for the financial support and guidance.

The VUNA Project was initiated by the Bill & Melinda Gates

Foundation, which also provided most of the funding. Additional

funding was provided by the Swiss National Science Foundation,

the United States National Science Foundation, and the project

partners. We also thank all researchers, field workers, laboratory

and administrative staff for their great commitment to the project.

Electrolysis: Hanspeter Zöllig, Kai M. Udert, Eberhard Morgenroth,

Anja Sutter, Christina Fritzsche, Annette Remmele (Eawag,

Process Engineering).

Struvite Precipitation: Chris Buckley, Chris Brouckaert,

Maximilian Grau, Sara Rhoton (UKZN, Pollution Research Group);

Lungiswa Zuma, Mlungisi Mthembu, Samukelisiwe ‘Thandi’ Cele,

Musawenkosi ‘Moussa’ Ndlovu (EWS).

Process Control : Kris Villez, Alma Mašic, Bastian Etter,

Kai M. Udert, Ana Santos, Lorenzo Garbani Marcantini,

Angelika Hess, Elisabeth Grimon, Christian Thürlimann

(Eawag, Process Engineering).

Risks of Using Urine

Removing Pharmaceuticals: Christa S. McArdell,

Birge D. Oezel Duygan, Annette Remmele (Eawag, Environmental

Chemistry); Linda Strande (Eawag, Sandec); Kai M. Udert,

Alexandra Fumasoli (Eawag, Process Engineering).

Inactivating Pathogens: Heather N. Bischel, Tamar Kohn,

Loïc Decrey, Manfred Schoger, Ariane Schertenleib,

Sara Oppenheimer, Simon Schindelholz (EPFL, Environmental

Chemistry); Kai M. Udert (Eawag, Process Engineering).

Agriculture

Fertiliser Trials: Astrid Oberson, Christophe Bonvin,

Emmanuel Frossard, Simone Nanzer (ETHZ, Agricultural Sciences);

Alfred Odindo, Irene Bame, William Musazura (UKZN, School of

Agricultural, Earth & Environmental Sciences).

Urine Collection Networks

Optimising Urine Collection: Teddy Gounden, Hope Joseph,

Kevyn Govender, Scelo Xulu, Wonderboy Sithole, Andrew Lupke,

Lucky Sibiya, Maximilian Grau (EWS); Elena Friedrich (UKZN, Civil

Engineering); Elizabeth Tilley (ETHZ, NADEL); Heiko Gebauer

(Eawag, Environmental Social Sciences).

Performance Modelling: Max Maurer, Thomas Hug,

Theresa Rossboth, Andreas Scheidegger (Eawag, Urban Water

Management); Kai M. Udert (Eawag, Process Engineering).

Social and Economic Aspects

Social Acceptance: Lisa Frost Ramsay, Marietjie Coertzen

(UKZN, Environmental Sciences);

Elisa Roma (UKZN, Pollution Research Group).

Campaigning for Health and Hygiene: Nosipho Mkhize (EWS);

Myra Taylor (UKZN, Public Health); Khwela Thandeka Patience,

Thembelihle Hlengwa, Sanele Ndlovu, Nokukhanya Khuzwayo,

Philani Mngoma, Thembelihle Gwala, Nonhle Makhonza (EWS,

Community Facilitators); Cebo Gumbi, Lindiwe Gumede,

Phindile Zwane, Silindile Radebe, Siyaphila Zuma, Lerato Mateza

(EWS, Health Promoters).

Incentives for Urine Production: Elizabeth Tilley, Isabel Günther

(ETHZ, NADEL); Leanne MacGregor, Peter Spohn (UKZN, Pollution

Research Group); Scelo Xulu, Andrew Lupke (EWS); Musawenkosi

‘Moussa’ Ndlovu, Samukelisiwe ‘Thandi’ Cele, Dennis Khomo

(EWS, Collection Coordination); Bongekile Mngwengwe,

Nomvula Ncwane, Mondli Ngidi (EWS, Field Work Managers).

38 VUNA Final Report 2015

Literature

Further Readings

Selected VUNA Publications and Conference Contributions

Urine Treatment Processes

Etter, B., Hug, A., Udert, K.M. (2013) Total nutrient recovery from urine –

operation of a pilot-scale nitrification reactor. WEF/IWA International

Conference on Nutrient Removal and Recovery 2013, 28 - 31 July,

Vancouver, Canada.

Etter, B., Udert, K.M., Gounden, T. (2014) VUNA – Nutrient harvesting

from urine: lessons from field studies. WISA Biennal Conference,

25 - 28 May, Mbombela, South Africa.

Etter, B., Udert, K.M., Gounden, T. (2014) VUNA – Scaling up nutrient

recovery from urine. Technology for Development International

Conference, 4 - 6 June 2014, EPFL, Lausanne, Switzerland.

Florin, A. (2013) Full nitrification of urine by adding a base. Master’s thesis,

ETH Zurich.

Fritzsche, C. (2012) The formation of chlorinated organics during electro-

lytic urine treatment. Master’s thesis, ETH Zurich.

Fumasoli, A. (2015) Stabilization of urine with nitrification as pre-treatment

for nutrient recovery (preliminary title). PhD thesis, ETH Zurich. In prep.

Fumasoli, A., Morgenroth, E., Udert, K.M. (2015) Modeling the low pH

limit of nitrosomonas-type bacteria in high-strength nitrogen waste-

waters. Submitted to Water Research.

Fumasoli, A., Weissbrodt, D., Wells, G.F., Bürgmann, H., Mohn, J.,

Morgenroth E., Udert K.M. (2015) Low pH selects for nitrosococcus

in high and nitrosospira in low salt environments. In preparation.

Fumasoli, A., Etter, B., Sterkele, B., Morgenroth, E., Udert, K.M. (2015)

Complete nutrient recovery from urine in a pilot-scale nitrification/

distillation plant. IWA Conference Nutrient Removal and Recovery,

18 - 21 May, Gdansk, Poland. In Preparation.

Grau, M.G.P., Rhoton, S., Brouckaert, C.J., Buckley, C.A. (2015) Develop-

ment of a fully automated struvite reactor to recover phosphorus

from source-separated urine collected at urine diversion toilets in

eThekwini. Accepted for Water SA.

Grau, M.G.P., Etter, B., Hug, A., Wächter, M., Udert, K.M., Brouckaert, C.,

Buckley, C. (2012) Nutrient recovery from urine: Operation & optimi-

zation of reactors in eThekwini. International Faecal Sludge Manage-

ment Conference, 29 - 31 Oct, Durban, South Africa.

Grau, M.G.P., Etter, B., Udert, K.M., Brouckaert, C.J., Buckley, C.A. (2012)

Development and operation of struvite reactors to recover phos-

phorus from source separated urine in eThekiwini. WISA Biennial

Conference, 05 - 09 May, Cape Town, South Africa.

Grau, M.G.P., Rhoton, S.L., Brouckaert, C.J., Buckley, C.A. (2013) Devel-

opment of a fully automated struvite reactor to recover phosphorus

from source separated urine collected at urine diversion toilets in

eThekwini. WEF/IWA International Conference on Nutrient Removal

and Recovery 2013, 28 - 31 July, Vancouver, Canada.

Grimon, E. (2015) Sensor characterization & monitoring for soft-sensing

of urine nitrification systems (preliminary title). Master’s thesis,

ETH Zurich. In preparation.

Hess, A. (2015) Feasibility of UV-Vis spectrophotometry for nitrite esti-

mation in urine nitrification systems. Master’s thesis, ETH Zurich.

In preparation.

Huber, S. (2011) Temperature dependent removal of sodium chloride

(NaCl) from synthetic nitrified urine. Master’s thesis, Karlsruhe

Institute of Technology.

Mašic, A., Santos, A., Etter, B., Udert, K.M., Villez, K. (2015) Estimation of

nitrite in source-separated nitrified urine with UV spectrophotometry.

In preparation.

Mašic, A., Santos, A., Etter, B., Udert, K.M., Villez, K. (2015) Estimation of

nitrite concentration in a urine nitrification reactor by means of UV

spectrophotometry. IWA Conference on Nutrient Removal and Re-

covery 2015, 18 - 21 May, Gdansk, Poland.

Mašic, A., Villez, K. (2014) Model-based observers for monitoring of a

biological nitrification process for decentralized wastewater treatment.

IWA International Conference Ecotechnologies for Wastewater

Treatment, 23 - 25 June, Verona, Italy.

Remmele, A. (2013) The influence of anode material and current density

on the emissions of disinfection by-products (DBPs) during electro-

lytic treatment of stored urine. Master’s thesis, ETH Zurich.

Rhoton, S., Grau, M., Brouckaert, C.J., Gouden, G., Buckley, C.A. (2014)

Field operation of a simple struvite reactor to produce phosphorus

fertiliser from source-separated urine in eThekwini. WISA Biennal

Conference, 25 - 28 May, Mbombela, South Africa.

Sutter, A. (2014) A hybrid MBBR-electrolysis urine nitrification system:

the interplay of electrolysis and bacteria. Master’s thesis, ETH Zurich.

Udert, K.M., Buckley, A.C., Wächter, M., McArdell, C.S., Kohn, T.,

Strande, L., Zöllig, H., Hug, A., Oberson, A., Etter, B. (2015)

Te ch -

nologies for the treatment of source-separated urine in the eThek-

wini municipality. Accepted for Water SA.

Udert, K.M., Etter, B., Gounden, T., (2012) VUNA, Nutrient harvesting

from urine. International Faecal Sludge Management Conference,

29 - 31 Oct, Durban, South Africa.

Udert, K.M., Wächter, M. (2012) Complete nutrient recovery from source-

separated urine by nitrification and distillation. Water Research 46(2),

453 - 464.

Uhlmann, C. (2014) Complete nitrification of urine. Master’s thesis,

ETH Zurich.

Wächter, M., Huber, S., Kluge, J., Mazzotti, M., Udert, K.M. (2015) Selec-

tive crystallization of sodium chloride (NaCl) from partially nitrified

urine. In preparation.

Wächter, M., Schwaninger, M., Gmeinwieser, T., Udert K.M. (2015)

Safety assessment for production and storage of nitrified and

concentrated fertilizer from human urine. In preparation.

Zöllig, H. (2015) Electrolysis for the treatment of stored source-separated

urine (preliminary title). PhD thesis. ETH Zurich. In preparation.

Zöllig, H., Fritsche, C., Morgenroth, E., Udert, K. M. (2015) Direct electro-

chemical oxidation of ammonia on graphite as a treatment option

for stored source-separated urine. Water Research 69, 284 - 294.

Zöllig, H., Morgenroth, E., Udert, K.M. (2015) Inhibition of direct ammonia

oxidation due to a change in local pH. Accepted for Electrochimica Acta.

Zöllig, H., Remmele, A., Fritzsche, C., Morgenroth, E., Udert, K.M. (2015)

Formation of chlorination by-products and their emission pathways

in chlorine mediated electro-oxidation of urine on active and inactive

anodes. Submitted to Environmental Science and Technology.

Zöllig, H., Remmele, A., Morgenroth, E., Udert, K.M. (2015) The removal

of ammonia and organic substances from real stored urine by

chlorine mediated electro-oxidation – effects of urine composition

and electrode material. In preparation.

39VUNA Final Report 2015

Zöllig, H., Fritzsche, C., Morgenroth, E., Udert, K.M. (2013) Electro-

chemical oxidation of ammonia on graphite – A treatment option for

source-separated urine. WEF/IWA International Conference on

Nutrient Removal and Recovery, 28 - 31 July, Vancouver, Canada.

Risks of Using Urine

Bischel, H.N., Oezel, B.D., Strande, L., McArdell, C.S., Udert, K.M., Kohn, T.

(2015) Pathogens, pharmaceuticals and antibiotic resistance genes in

source-separated urine in eThekwini, South Africa. In preparation.

Bischel, H.N., Schertenleib, A., Fumasoli, A., Udert, K.M., Kohn, T. (2014)

Inactivation kinetics and mechanisms of bacterial and viral pathogen

surrogates during urine nitrification. Environmental Science: Water

Research & Technology 1, 65 - 76.

Bischel, H.N., Kohn, T. (2013) Presence and inactivation of bacteria and

viruses in urine storage and recycling systems in Durban, South Africa.

International Symposium on Health-Related Water Microbiology,

15 - 20 Sep, Florianopólis, Brazil.

Bischel, H.N., Schindelholz, S., Schoger, M., Decrey, L., Bosshard, F.,

Udert, K.M., Kohn, T. (2015) Bacteria inactivation during drying of

struvite fertilizers produced from stored urine. In preparation.

Decrey, L. (2015) Virus inactivation in human excreta and animal manure.

PhD thesis, EPF Lausanne.

Decrey, L., Kazama, S., Udert, K.M., Kohn, T. (2015) Ammonia as an in-situ

sanitizer: inactivation kinetics and mechanisms of the ssRNA virus

MS2 by NH3. Environmental Science & Technology 49, 1060 -1067.

Decrey, L., Udert, K.M., Tilley, E., Pecson, B.M., Kohn, T. (2011) Fate of

the pathogen indicators phage ΦX174 and ascaris suum eggs during

the production of struvite fertilizer from source-separated urine.

Water Research 45, 4960 - 4972.

Oezel Duygan, B.D., Udert, K.M., Remmele, A., McArdell, C.S. (2015)

Fate of pharmaceuticals in source-separated urine during storage,

biological treatment and powdered activated carbon adsorption.

In preparation.

Oezel, B.D. (2013) Fate of pharmaceuticals during urine treatment in

laboratory batch experiments: can urine be used as fertilizer in

South Africa? Master’s thesis, ETH Zurich.

Schertenleib, A. (2014) Inactivation of pathogens in urine nitrification

reactors, Master’s thesis, EPF Lausanne.

Schoger, M. (2011) Bacterial inactivation in struvite recovered from

urine in South Africa. Master’s thesis, EPF Lausanne.

Agriculture

Bonvin, C., Etter, B., Udert, K.M., Frossard, E., Nanzer, S., Tamburini, F.,

Oberson, A. (2015) Plant uptake of phosphorus and nitrogen recycled

from synthetic source-separated urine. AMBIO, 44 (Suppl. 2), 217 - 227.

Bonvin, C. (2013) Recycling of phosphorus & nitrogen from human urine:

evaluation of urine based fertilizers in a pot experiment. Master’s

thesis, ETH Zurich.

Oberson, A., Bonvin, C., Nanzer, S.A., Tamburini, F., Etter, B., Udert, K.M.,

Frossard, E. (2013) Plant uptake of phosphorus recycled from

human urine and sewage sludge ashes. International Phosphorus

Workshop, 9 -13 Sep, Uppsala, Sweden.

Meyer, G., Nanzer, S.A., Bonvin, C., Udert, K.M., Etter, B., Mäder, P.,

Thonar, C., Frossard, E., Oberson, A. (2014) Plant uptake of phos-

phorus recycled from human waste water and sewage sludge ashes.

World Congress of Soil Science, 8 -13 June, Jeju, Korea.

Urine Collection Networks

Hug, T., Maurer, M. (2012) Stochastic modeling to identify requirements

for centralized monitoring of distributed wastewater treatment.

Water Science & Technology, 65(6), 1067 -1075.

Hug, T., Maurer, M., Udert, K.M. (2012) Model-based performance evalu-

ation of the collection of source-separated urine. International Faecal

Sludge Management Conference, 29 - 31 Oct, Durban, South Africa.

Joseph, H.R., Gebauer, H., Friedrich, E., Buckley, C.A. (2014) Institution-

alised Collection for Rural On-Site Sanitation. WISA Biennal Confer-

ence, 25 - 28 May, Mbombela, South Africa.

Joseph, H.R. (2015) Develop and describe a suitable logistic collection

system for urine harvesting in eThekwini. Master’s thesis, University

of KwaZulu-Natal. In preparation.

Rossboth, T., Udert, K.M., Maurer, M. (2015) Using stochastic modelling to

support urine collection scheme planning in South Africa. In preparation.

Rossboth, T. (2013) Model-based systems analysis of the collection

management of source-separated urine in eThekwini Municipality,

South Africa. Master’s Thesis, University of Natural Resources & Life

Sciences (BOKU), Vienna.

Social and Economic Aspects

Etter, B., Etter, L., Joseph, H.R., Grau, M.G.P., Chetty, S., Gounden, T.,

Gebauer, H., Udert, K.M. (2015) Financial opportunities for complete

nutrient recovery from source-separated urine in eThekwini, South

Africa. In preparation.

Mkhize, N. (2015) The role of health & hygiene education in the accept-

ance, utilisation, and maintenance of urine diversion toilets in rural

communities of KwaZulu-Natal (preliminary title). Master’s thesis,

University of KwaZulu-Natal. In preparation.

Mkhize, N., Taylor, M., Ramsay, L.F., Buckley C.A., Gounden, T. (2015)

Urine-diverting toilets acceptance, use and maintenance: through

users eyes. In preparation.

Mkhize, N., Coertzen, M., Taylor, M., Ramsay, L., Udert, K.M., Gouden, T.,

Buckley, C.A. (2014) Promoting sanitation and nutrient recovery

through urine separation: The role of health and hygiene education and

social acceptance factors. WISA Biennal Conference, 25 - 28 May,

Mbombela, South Africa.

Okem, A.E., Xulu, S., Tilley, E., Buckley, C., Roma E. (2013) Assessing

perceptions and willingness to use urine in agriculture: a case study

from rural areas of eThekwini municipality, South Africa. Journal of

Water Sanitation and Hygiene for Development 3(4), 582-591.

Ramsay, L.F., Coertzen, M., Buckley, C.A., Gounden, T. (2015) The power

of perception: views and practices related to urine diversion toilets

in the eThekwini Municipality, South Africa. In preparation.

Roma, E., Philp, K., Buckley, C., Xulu, S., Scott, D. (2013) User percep-

tions of urine diversion dehydration toilets: Experiences from a cross-

sectional study in eThekwini Municipality. Water SA 39(2), 305-312.

Tilley, E. (2015) Acceptance, impact & feasibility of incentives for increasing

toilet use: a case study in eThekwini, South Africa. PhD Thesis, ETHZ.

Tilley, E., Logar, I., Guenther, I. (2015) Giving respondents time to think

about a conditional cash transfer program: a choice experiment in

rural South Africa. In preparation.

Tilley, E., Guenther, I. (2015) The impact of conditional cash transfers

on toilet use. In preparation.

Tilley, E. (2015) Cost-effectiveness and community impacts of two

urine-collection programs in rural South Africa. In preparation.

Tilley, E., Günther, I. (2014) Mobile phones for collecting WaSH data in low-

income countries. WEDC International Conference, Hanoi, Vietnam.

Tilley, E., Günther, I. (2012) Incentivizing sanitation through urine collection.

International Faecal Sludge Management Conference, 29 - 31 Oct,

Durban, South Africa.

>> For an updated list including further reports, brochures,

posters, movies etc. visit: www.vuna.ch

Editors:

Bastian Etter, Kai M. Udert, Teddy Gounden

Contact:

In South Africa:

Teddy Gounden, eThekwini Water & Sanitation, Durban

+27 31 311 87 93, teddy.gounden@durban.gov.za

In Switzerland:

Kai M. Udert, Eawag - Swiss Federal Institute of Aquatic Science & Technology, Dübendorf, Switzerland

+41 58 765 53 60, kai.udert@eawag.ch

Citation of this report:

Etter, B., Udert, K.M., Gounden, T. (editors) (2015) VUNA Final Report. Eawag, Dübendorf, Switzerland

Project Partners:

Eawag – Swiss Federal Institute of Aquatic Science & Technology

EWS – eThekwini Water & Sanitation

UKZN – University of KwaZulu-Natal

ETHZ – Swiss Federal Institute of Technology Zurich

EPFL – Swiss Federal Institute of Technology Lausanne

VUNA - By recovering nutrients from urine, we want to develop a dry

sanitation system, which is affordable, produces a valuable fertiliser,

promotes entrepreneurship and reduces pollution of water resources.

www.vuna.ch

Elisabeth Real

Embracing Urine Diversion for Sustainable (Waste)Water Management: Common Practices, Advantages, and Challenges

Article

Oct 2024

Source-separation of urine (urine diversion) is a well-established concept with proven sanitation benefits, promoting sustainable (waste)water management and circular economy, gaining increased attention worldwide. Although urine comprises only 1% in municipal wastewater by volume, it mostly accounts for nutrient loads in wastewater (85–90% of N, 50–80% of P, and 80–90% of K). Source-separation of urine: improves sanitation, conserves water, can partly substitute synthetic fertilizers in agriculture, and reduces energy and space requirements at wastewater treatment plants. This paper reviews the developments in source separation and valorization of urine, its benefits, methods for treatment, and challenges for implementation. Further, implications of source-separation of urine in Indian context (as an example of developing/emerging economy) is highlighted.

Urine as Biobased Fertilizer: The Netherlands as Case Study

Article

Full-text available

May 2024

Humankind has grown ever more dependent on mineral fertilizer to feed a growing world population. However, nutrients are rarely recovered and recycled after consumption, leading to environmental waste issues now and potential supply issues in the future. Urine is rich in these nutrients and therefore a prime candidate as precursor for biobased fertilizers. This work presents a case study to remove contaminants – predominantly pharmaceuticals – from human urine using activated carbon adsorbents in an effort to adhere to Dutch fertilizer legislation. In the urine, three pharmaceuticals were identified by target analysis and 11 other contaminants by suspect screening using liquid chromatography quadrupole time of flight mass spectrometry (LC-QTOF/MS). These were successfully removed by treatments with both granulated and powdered activated carbon, albeit with a loss of 16-17% and 2-4% of dissolved nutrients, respectively. Further screening of inorganic contaminants and persistent organic pollutants by inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography quadrupole-orbitrap mass spectrometry (GC-Q-Orbitrap/MS) showed that all prerequisites for fertilizer status are met, paving the way for its future legal use as biobased fertilizer in the Netherlands.

Communicating source separation of urine

Article

Full-text available

Mar 2021

One of the main issues regarding the implementation of source-separation-based sanitation systems is user acceptance, which is related directly to the state of knowledge of citizens. A communication platform for the exhibition and interactive information on the topic of resource-oriented sanitation (ROS) was developed as part of the P-BANK transdisciplinary project. The P-BANK platform is based on a toilet in the public space. The communication concept focusses on the actual use of the toilets and the surrounding nutrient cycle. The central object of the communication at the P-BANK, as its name suggests, is the macronutrient phosphorus. This simplification creates a symbolic effect which is supported by the ambiguity of the sound of the chemical symbol “P” for phosphorus in connection with urinating (to pee). Furthermore, this reduction aims at shortening the messages and simplifying the information transfer. In the first project phase, the transportable system was field-tested and evaluated in the context of the 100th anniversary of the Bauhaus in Weimar. After positive reviews and experiences concerning the performance of the technical facilities and the success of the communication concept, the P-BANK will be tested and evaluated in further awareness-raising campaigns.

Developing sanitation planning options: A tool for systematic consideration of novel technologies and systems

Article

Full-text available

Oct 2020

To provide access to sustainable sanitation for the entire world population, novel technologies and systems have been developed. These options are often independent of sewers, water, and energy and therefore promise to be more appropriate for fast-growing urban areas. They also allow for resource recovery and and are adaptable to changing environmental and demographic conditions what makes them more sustainable. More options, however, also enhance planning complexity. Structured decision making (SDM) can help balance opposing interests. Yet, most of the current research focuses on the selection of a preferred option, assuming that a set of appropriate options is available. There is a lack of reproducible methods for the identification of sanitation system planning options that can consider the growing number of available technology and the many possible system configurations. Additionally, there is a lack of data, particularly for novel options, to evaluate the various sustainability criteria for sanitation.To overcome this limitation, we present a novel software supported approach: the SANitation sysTem Alternative GeneratOr (Santiago). To be optimally effective, Santiago is required to be integrated into an SDM approach. In this paper, we present all the elements that such an integration requires and illustrate these methods at the case of Arba Minch, a fast growing town in Ethiopia. Based on this example and experiences from other cases, we discuss the lessons learnt and present the advantages potentially brought by Santiago for sanitation planning The integration requires four elements: a set of technologies to be looked at, decision objectives for sustainable sanitation, screening criteria to evalute technology appropriateness, and about the technologies and the casea. The main output is a set of sanitation system options that is locally appropriate, diverse in order to reveal trade-offs, and of a manageable size. To support the definition of decision objectives, we developed a generic objective hierarchy for sustainable sanitation. Because one of the main challenges lies in the quantification of screening criteria, we established the data for 27 criteria and 41 technologies in a library.The case studies showed, that if the integration is successful, then Santiago can provide substantial benefits: (i) it is systematic and reproducible; (ii) it opens up the decision space with novel and potentially more appropriate solutions; (iii) it makes international data accessible for more empirical decision making; (iv) it enables decisions based on strategic objectives in line with the sustainable development goals; (v) it allows to prioritise appropriate and resource efficient systems right from the beginning (vi) and it contributes to a more citywide inclusive approach by birding strategic objectives with an area-based appropriateness assessment. The here presented approach enables the prioritisation of appropriate and resource efficient sanitation technologies and systems in strategic planning. Thereby this approach contributes to SDG 6.2, 6.3, and 11, sustainable sanitation for all.

Comparing Ion Exchange Adsorbents for Nitrogen Recovery from Source-Separated Urine

Article

Jan 2017
ENVIRON SCI TECHNOL

Separate collection of urine, which is only 1% of wastewater volume but contains the majority of nitrogen humans excrete, can potentially reduce the costs and energy input of wastewater treatment and facilitate recovery of nitrogen for beneficial use. Ion exchange was investigated for recovery of nitrogen as ammonium from urine for use as a fertilizer or disinfectant. Cation adsorption curves for four adsorbents (clinoptilolite, biochar, Dowex 50, and Dowex Mac 3) were compared in pure salt solutions, synthetic urine, and real stored urine. Competition from sodium and potassium present in synthetic and real urine did not significantly decrease ammonium adsorption for any of the adsorbents. Dowex 50 and Dowex Mac 3 showed nearly 100% regeneration efficiencies. Estimated ion exchange reactor volumes to capture the nitrogen for one week from a four-person household were lowest for Dowex Mac 3 (5 L) and highest for biochar (19 L). Although Dowex Mac 3 had the highest adsorption capacity, material costs ($/g N removed) were lower for clinoptilolite and biochar because of their substantially lower unit cost.

Source separation of urine and treatment: Impact on energy consumption, greenhouse gas emissions, and decentralised wastewater treatment process

Article

Apr 2024
DESALINATION

Uptake of selected antiretrovirals by pepper (Capsicum annum), radish (Raphanus sativus), and ryegrass (Lolium perenne) grown on two contrasting soils and fertilized with human urine-derived fertilizers

Article

Full-text available

Jun 2023
SCI TOTAL ENVIRON

The use of urine-derived fertilizers has several economic and environmental advantages. However, there is concern that pharmaceutical residues present in urine could enter the food chain after plant uptake and pose potential risks to human and animal health. A pot experiment was conducted to evaluate the uptake of nine target antiretroviral drugs (ARVDs) by pepper (Capsicum annum), ryegrass (Lolium perenne) and radish (Raphanus sativus) grown in two soils of contrasting texture and organic matter content and fertilized with stored urine, nitrified urine concentrate (NUC), and struvite. Nevirapine was the only ARVD detected in crops grown with NUC and struvite on both soils, but the concentrations were below the limit of quantification. Plants fertilized with stored urine absorbed lamivudine, ritonavir, stavudine, emtricitabine, nevirapine, and didanosine, while abacavir, efavirenz and zidovudine were not detected. The ARVDs detected in the soils after harvest were significantly higher in the soil with high organic matter and clay content. To assess direct human exposure the estimated daily dietary intake (DDI) of ARVDs by consumption of the pepper and radish fertilized with stored urine was compared with the Threshold of Toxicological Concern (TTC) values based on the Cramer classification tree. The calculated DDI values for all ARVDs were about 300-3000 times lower than the TTC values for class III compounds. Therefore, daily consumption of these crops fertilized with stored urine does not pose a health risk to the consumer. Future research is required to assess the impact of ARVD metabolites, which may be more harmful to human health than the parent compounds.

Nitrogen Oxidation and Carbon Removal from High Strength Nitrogen Habitation Wastewater with Nitrification in Membrane Aerated Biological Reactors

Article

Full-text available

Aug 2021

Bioreactors for space habitation systems have unique constraints. One type of reactor that could meet these constraints are membrane aerated biological reactors (MABRs). The objective of this work was to establish the performance and optimal loading capacities of multiple MABRs with a variety of habitation waste streams. The MABRs operated over a large range of organic nitrogen (ON) and organic carbon (OC) loading rates (36 to 220 g/m³-d and 20 to 200 g/m³-d, respectively) across all wastewaters excluding humidity condensate (HC) where ON and OC loading rates ranged from 1.6-11 g/m³-d and 7-55 g/m³-d, respectively. OC and ON transformation rates (29 to 210 g/m³-d and 23 to 170 g/m³-d, respectively) were proportional to loading rates and similar to MABRs treating terrestrial high strength wastewaters at similar loadings. MABR maximum loading rates are limited by ON oxidation which controls pH. Above a pH of ~7.8 ON removal is inhibited by free ammonium due to the elevated concentrations of ON in all wastewaters excluding HC. While loading rates are lower than typical terrestrial systems, the MABRs stably operated for up to 5 years with limited maintenance and no solids processing. This work supports the use of MABRs to reliably stabilize habitation wastewaters with minimal consumables. These results also support the use of these MABRs for terrestrial high strength, low volume wastewaters where complex technology may be unsupportable, such as in rural or developing communities with no centralized treatment or for applications where typical two-phase aeration can lead to undesirable off gassing.

The effect of giving respondents time to think in a choice experiment: a conditional cash transfer programme in South Africa

Article

Full-text available

Nov 2016

We conducted a choice experiment (CE) to estimate willingness to accept (WTA) values for a planned conditional cash transfer (CCT) programme designed to increase toilet use in South Africa. The payment is made conditional on using a toilet and bringing urine to a central collection point. In a split-sample approach, a segment of respondents were given time to think (TTT) (24 hours) about their responses, while the remaining respondents had to answer immediately. We found significant differences in the choice behaviour between the subsamples. To validate the stated preferences with actual behaviour, a CCT programme was implemented afterwards. The stated WTA estimates were far below those revealed by actual behaviour for both subsamples. Contrary to our expectations, the TTT group had underestimated their actual WTA values by an even larger margin. The preferences for various attributes were nevertheless useful in informing the design of the real intervention.

The Impact of Conditional Cash Transfer on Toilet Use in eThekwini, South Africa

Article

Full-text available

Oct 2016

In the developing world, having access to a toilet does not necessarily imply use: infrequent or non-use limits the desired health outcomes of improved sanitation. We examine the sanitation situation in a rural part of South Africa where recipients of novel, waterless “urine-diverting dry toilets” are not regularly using them. In order to determine if small, conditional cash transfers (CCT) could motivate families to use their toilets more, we paid for urine via different incentive-based interventions: two were based on volumetric pricing and the third was a flat-rate payment (irrespective of volume). A flat-rate payment (approx. €1) resulted in the highest rates of regular (weekly) participation at 59%. The low volumetric payment (approx. €0.05/L) led to regular participation rates of only 12% and no increase in toilet use. The high volumetric payment (approx. €0.1/L) resulted in lower rates of regular participation (35%), but increased the average urine production per household per day by 74%. As a first example of conditional cash transfers being used in the sanitation sector, we show that they are an accepted and effective tool for increasing toilet use, while putting small cash payments in the hands of poor, largely unemployed populations in rural South Africa.

Cost-effectiveness and community impacts of two urine-collection programs in rural South Africa

Article

Full-text available

Jan 2015

Elizabeth Anne Tilley

As the number of technologies and programming approaches for improving global sanitation grows, there is an increasing need to evaluate the cost-effectiveness of each so that policy can be driven by informed decisions that consider cost as well as impact. I use data from two different urine-collection programs that were implemented in rural South Africa to model the cost-effectiveness of each in terms of the cost per litre of urine collected and the cost per household, over a range of operational values. One program was based on conditional cash transfers with the aim of increasing toilet use, while the second program was centrally managed and designed to be logistically simple for the municipality. Urine from both programs was used as a feedstock in nutrient recovery technologies. In comparing the results of the two models I find a paradox. Urine that is collected from households by the municipality is less expensive than incentivized urine collection on both a volumetric and household basis, but only at urine collection rates that cannot be achieved without incentives. Conversely, the incentivized collection is more cost effective when the collection rates are low, but at rates that would correspond to very low incentive prices, rendering the incentive scheme useless. My results illustrate the importance of cost-effectiveness analysis as a tool in sanitation programming but I also highlight the need to view the data with a more nuanced approach that considers the complexities of program implementation in poor, rural communities as the mathematical optimal may not correspond to a realistic, or socially desirable one. Incentivized urine collection brings jobs, money, and improved sanitation to the community, and frees up municipal staff to focus on other, more technical problems. If the goal is really to increase toilet use, acceptance, and strive towards 100% sanitation coverage, incentivized toilet use should be considered.

Operating a pilot-scale nitrification/distillation plant for complete nutrient recovery from urine

Article

Full-text available

Sep 2015

Source-separated urine contains most of the excreted nutrients, which can be recovered by using nitrification to stabilize the urine before concentrating the nutrient solution with distillation. The aim of this study was to test this process combination at pilot scale. The nitrification process was efficient in a moving bed biofilm reactor with maximal rates of 930 mg N L−1 d−1. Rates decreased to 120 mg N L−1 d−1 after switching to more concentrated urine. At high nitrification rates (640 mg N L−1 d−1) and low total ammonia concentrations (1,790 mg NH4-N L−1 in influent) distillation caused the main primary energy demand of 71 W cap−1 (nitrification: 13 W cap−1) assuming a nitrogen production of 8.8 gN cap−1 d−1. Possible process failures include the accumulation of the nitrification intermediate nitrite and the selection of acid-tolerant ammonia oxidizing bacteria. Especially during reactor start-up, the process must therefore be carefully supervised. The concentrate produced by the nitrification/distillation process is low in heavy metals, but high in nutrients, suggesting a good suitability as an integral fertilizer.

Evaluation of an automated struvite reactor to recover phosphorus from source-separated urine collected at urine diversion toilets in eThekwini

Article

Full-text available

Apr 2015
WATER SA

In the present study we attempted to develop a reactor system to recover phosphorus by struvite precipitation, and which can be installed anywhere in the field without access to a laboratory. A reactor was developed that can run fully automated and recover up to 93% of total phosphorus (total P). Turbidity and conductivity signals were investigated as automation proxies for magnesium dosage, thus making laboratory phosphate measurements to determine the exact magnesium dosage unnecessary. Conductivity is highly influenced by the dosing parameters (molarity and pump speed) and turbidity is affected by particle size distribution issues. Algorithms based on both conductivity and turbidity signals were not able to detect the precipitation endpoint in real time. However it proved possible to identify the endpoint retrospectively from the conductivity signal, and thereafter to dose an algorithm-calculated volume of urine to use up the excess magnesium dosed. © 2015, South African Water Research Commission. All rights reserved.

Modeling the low pH limit of Nitrosomonas eutropha in high-strength nitrogen wastewaters

Article

Full-text available

Jun 2015

In wastewater treatment, the rate of ammonia oxidation decreases with pH and stops very often slightly below a pH of 6. Free ammonia (NH3) limitation, inhibition by nitrous acid (HNO2), limitation by inorganic carbon or direct effect of high proton concentrations have been proposed to cause the rate decrease with pH as well as the cessation of ammonia oxidation. In this study, we compare an exponential pH term common for food microbiology with conventionally applied rate laws based on Monod-type kinetics for NH3 limitation and non-competitive HNO2 inhibition as well as sigmoidal pH functions to model the low pH limit of ammonia oxidizing bacteria (AOB). For this purpose we conducted well controlled batch experiments which were then simulated with a computer model. The results showed that kinetics based on NH3 limitation and HNO2 inhibition can explain the rate decrease of ammonia oxidation between pH 7 and 6, but fail in predicting the pH limit of Nitrosomonas eutropha at pH 5.4 and rates close to that limit. This is where the exponential pH term becomes important: this term decreases the rate of ammonia oxidation to zero, as the pH limit approaches. Previously proposed sigmoidal pH functions that affect large pH regions, however, led to an overestimation of the pH effect and could therefore not be applied successfully. We show that the proposed exponential pH term can be explained quantitatively with thermodynamic principles: at low pH values, the energy available from the proton motive force is too small for the NADH production in Nitrosomonas eutropha and related AOB causing an energy limited state of the bacterial cell. Hence, energy limitation and not inhibition or limitation of enzymes is responsible for the cessation of the AOB activity at low pH values. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Inhibition of Direct Electrolytic Ammonia Oxidation Due to a Change in Local pH

Article

Full-text available

Mar 2015
ELECTROCHIM ACTA

Electrochemical ammonia oxidation has gained a lot ofattention recently as an efficient method for ammonia removal from wastewater, for the use in ammonia-based fuel cells and the production of high purity hydrogen. Thermally decomposed iridium oxide films (TDIROF) have been shown to be catalytically active for direct ammonia oxidation in aqueous solutions if NH3 is present. However, the processwasreported to be rapidly inhibited on TDIROF.Herein, we show that this fast inhibitionof direct ammonia oxidation does not result from surface poisoningby adsorbed elemental nitrogen (Nads). Instead, we proposethat direct ammonia oxidation and oxygen evolution can lead to a drop of the local pH at the electrode resulting in a low availability of the actual reactant, NH3. The hypothesis was tested with cyclic voltammetry (CV) experiments on stagnantand rotating disk electrodes (RDE). TheCV experiments on the stagnant electroderevealed that the decrease ofthe ammonia oxidation peaks wasconsiderably reduced by introducing an idle phase at open circuit potential between subsequent scans.Furthermore, the polarization of the TDIROFelectrode into the hydrogen evolution region (HER) resulted in increased ammonia oxidation peaks in the following anodic scans which can be explained with an increased local pH after the consumption of protons in the HER. On the RDE, the ammonia oxidation peaks did not decrease in immediately consecutive scans. These findings would not be expected if surface poisoning was responsible for the fast inhibition but they are in good agreement with the proposed mechanism of pH induced limitation by the reactant, NH3. The plausibility of the mechanism was also supported by our numerical simulations ofthe processes in the Nernstian diffusion layer.The knowledge about this inhibition mechanism of direct ammonia oxidation is especially important for the design of electrochemical cells for wastewater treatment.The mechanism is not only valid for TDIROF but also for other electrodes because it is independent of the electrode material.

Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry

Article

Sep 2015

Monitoring of nitrite is essential for an immediate response and prevention of irreversible failure of decentralized biological urine nitrification reactors. Although a few sensors are available for nitrite measurement, none of them are suitable for applications in which both nitrite and nitrate are present in very high concentrations. Such is the case in collected source-separated urine, stabilized by nitrification for long-term storage. Ultraviolet (UV) spectrophotometry in combination with chemometrics is a promising option for monitoring of nitrite. In this study, an immersible in situ UV sensor is investigated for the first time so to establish a relationship between UV absorbance spectra and nitrite concentrations in nitrified urine. The study focuses on the effects of suspended particles and saturation on the absorbance spectra and the chemometric model performance. Detailed analysis indicates that suspended particles in nitrified urine have a negligible effect on nitrite estimation, concluding that sample filtration is not necessary as pretreatment. In contrast, saturation due to very high concentrations affects the model performance severely, suggesting dilution as an essential sample preparation step. However, this can also be mitigated by simple removal of the saturated, lower end of the UV absorbance spectra, and extraction of information from the secondary, weaker nitrite absorbance peak. This approach allows for estimation of nitrite with a simple chemometric model and without sample dilution. These results are promising for a practical application of the UV sensor as an in situ nitrite measurement in a urine nitrification reactor given the exceptional quality of the nitrite estimates in comparison to previous studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pathogens and pharmaceuticals in source-separated urine in eThekwini, South Africa

Article

Aug 2015

In eThekwini, South Africa, the production of agricultural fertilizers from human urine collected from urine-diverting dry toilets is being evaluated at a municipality scale as a way to help finance a decentralized, dry sanitation system. The present study aimed to assess a range of human and environmental health hazards in source-separated urine, which was presumed to be contaminated with feces, by evaluating the presence of human pathogens, pharmaceuticals, and an antibiotic resistance gene. Composite urine samples from households enrolled in a urine collection trial were obtained from urine storage tanks installed in three regions of eThekwini. Polymerase chain reaction (PCR) assays targeted 9 viral and 10 bacterial human pathogens transmitted by the fecal-oral route. The most frequently detected viral pathogens were JC polyomavirus, rotavirus, and human adenovirus in 100%, 34% and 31% of samples, respectively. Aeromonas spp. and Shigella spp. were frequently detected gram negative bacteria, in 94% and 61% of samples, respectively. The gram positive bacterium, Clostridium perfringens, which is known to survive for extended times in urine, was found in 72% of samples. A screening of 41 trace organic compounds in the urine facilitated selection of 12 priority pharmaceuticals for further evaluation. The antibiotics sulfamethoxazole and trimethoprim, which are frequently prescribed as prophylaxis for HIV-positive patients, were detected in 95% and 85% of samples, reaching maximum concentrations of 6800 μg/L and 1280 μg/L, respectively. The antiretroviral drug emtricitabine was also detected in 40% of urine samples. A sulfonamide antibiotic resistance gene (sul1) was detected in 100% of urine samples. By coupling analysis of pathogens and pharmaceuticals in geographically dispersed samples in eThekwini, this study reveals a range of human and environmental health hazards in urine intended for fertilizer production. Collection of urine offers the benefit of sequestering contaminants from environmental release and allows for targeted treatment of potential health hazards prior to agricultural application. The efficacy of pathogen and pharmaceutical inactivation, transformation or removal during urine nutrient recovery processes is thus briefly reviewed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes

Article

Jul 2015
ENVIRON SCI TECHNOL

Chlorination by-products (CBPs) are harmful to human health and the environment. Their formation in chlorine mediated electro-oxidation is a concern for electrochemical urine treatment. We investigated the formation of chlorate, perchlorate and organic chlorination by-products (OCBPs) during galvanostatic (10, 15, 20 mA·cm(-2)) electro-oxidation of urine on boron-doped diamond (BDD) and thermally decomposed iridium oxide film (TDIROF) anodes. In the beginning of the batch experiments, the production of perchlorate was prevented by competing active chlorine and chlorate formation as well as by direct oxidation of organic substances. Perchlorate was only formed at higher specific charges (> 17 Ah·L(-1) on BDD and > 29 Ah·L(-1) on TDIROF) resulting in chlorate and perchlorate being the dominant CBPs (> 90% of initial chloride). BDD produced mainly short chained OCBPs (dichloromethane, trichloromethane and tetrachloromethane) whereas longer chained OCBPs (1,2-dichloropropane and 1,2-dichloroethane) were more frequently found on TDIROF. The OCBPs were primarily eliminated by electrochemical stripping: On BDD, this pathway accounted for 40% (dichloromethane) to 100% (tetrachloromethane) and on TDIROF for 90% (1,2-dichloroethane) to 100% (trichloromethane) of what was produced. A post-treatment of the liquid as well as the gas phase should be foreseen if CBP formation cannot be prevented by eliminating chloride or organic substances in a pretreatment.

VUNA: Valorisation of Urine Nutrients – Final Project Report

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