HOW CAN WE STOP THE SEWAGE?

Abstract

In Ecuador 46.4% of households lack access to sewerage systems, and then much wastewater is discharged from sewerage into the environment untreated. On the one hand dry toilet systems present themselves as an optimal solution against this backdrop; they mitigate the production of black water, whilst having fertilizer as the end product. On the other hand, they tend to have a low acceptance level by potential end users. This problem of social acceptance is then further exacerbated in urban areas. In order to overcome this, the design of an ecological dry/semi-dry toilet was carried out in two phases. The first phase consisted of purely sociological research, where the aim was to determine the basic design parameters that should be used for ecological toilet prototype. The second phase is the development of ecological toilet prototypes, which are then tested in terms of their level of acceptance/rejection by potential end users. The overall aim is to develop toilet prototypes that on the one hand mitigate the production of black water, whilst on the other are accepted with open arms by end users, and even preferred over the conventional toilet common to urban areas.

Full text

Interaction between Theory and Practice in Civil Engineering and Construction
Edited by Komurlu, R., Gurgun, A. P., Singh, A., and Yazdani, S.
Copyright © 2016 ISEC Press
ISBN: 978-0-9960437-2-4
603
HOW CAN WE STOP THE SEWAGE?
J. M. SÁEZ1, M. J. M. DAVIS1,2, M. L. GUTIÉRREZ1,2, A. VALLEJO1, and L. AYALA1
1Faculty of Architecture, Design and Arts, Pontificia Universidad Católica del Ecuador,
Quito, Ecuador
2Evolution Engineering, Design and Energy Systems Ltd., Exeter, UK
In Ecuador 46.4% of households lack access to sewerage systems, and then much
wastewater is discharged from sewerage into the environment untreated. On the one
hand dry toilet systems present themselves as an optimal solution against this
backdrop; they mitigate the production of black water, whilst having fertilizer as the
end product. On the other hand, they tend to have a low acceptance level by potential
end users. This problem of social acceptance is then further exacerbated in urban
areas. In order to overcome this, the design of an ecological dry/semi-dry toilet was
carried out in two phases. The first phase consisted of purely sociological research,
where the aim was to determine the basic design parameters that should be used for
ecological toilet prototype. The second phase is the development of ecological toilet
prototypes, which are then tested in terms of their level of acceptance/rejection by
potential end users. The overall aim is to develop toilet prototypes that on the one hand
mitigate the production of black water, whilst on the other are accepted with open arms
by end users, and even preferred over the conventional toilet common to urban areas.
Keywords: Dry toilet, Suction toilet, Manual suction, Wastewater treatment, Black
water, Grey water, Water recycling.
1 INTRODUCTION
1.1 The Problem of Water Treatment in Quito, Ecuador
In Ecuador wastewater treatment is a serious problem. According to the census of the
Ecuadorian National Institute of Statistics and Census (INEC 2010), only 53.6% of
households have a connection to public sewerage systems. In addition, wastewater
management makes up 53.3% of the average expenditure of national municipalities’
budget, totalling 179 142 858 USD (INEC 2011). In 2012 49.8% of national
municipalities carried out wastewater treatment, where a total of 128 000 000 m3 of
wastewater was processed. Despite this, 225 000 000 m3 of wastewater was discharged
untreated into the environment. The problem of wastewater treatment could be
approached either at a macro or micro scale. A macro scale would involve large,
expensive infrastructure works over a long time period. On the other hand, there is a
possibility to consider the problem at a micro, or individual scale. In this case, it is
suggested that every household would opt to change its toilet installation, to one that
avoids the production of black water. The objective of this research project is to
determine whether or not it is possible to mitigate the production of black water from

Komurlu, R., Gurgun, A. P., Singh, A., and Yazdani, S. (Eds.)
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Ecuadorian households, whilst at the same time upholding a maximum level of comfort
and lifestyle for the end users.
1.2 The Importance of Participative Design
In this research a participative design approach was adopted in accordance with Reason
and Bradbury (2008), which is both considered a methodology for investigation and an
approach to applied projects. In this sense, the researchers and end users worked
together in order to reach solutions that are innovative and sustainable. It is considered
to be a proven methodology in the generation of knowledge (Bergold 2007). In
practise, to achieve this it is necessary to involve the end user at all stages in the
development of the new product. In this manner it is guaranteed that the end result will
be in accordance with the users’ needs, given that they were involved in the entire
design process. This is reinforced by Liener and Larsen (2009), who mentions how in
current society innovative technologies are achieved by being as close to the end user
as possible. In is worth mentioning however, that honesty from the end users can only
be achieved by creating a secure setting in which the users feel comfortable in
expressing their true opinions (Bergold and Thomas 2012).
2 METHODOLOGY
For this research, a series of sociological investigations were carried out: eight site
visits to study homes with a dry toilet installed; twenty-eight semi-structured interviews
with hypothetical end users of the prototypes to be developed; twelve focus groups with
hypothetical end users of the prototypes to be developed. The results of the
sociological investigations were used for the parameters of design for an initial
prototype, which was given an initial evaluation through a preliminary social study
with end users.
3 RESULTS AND DISCUSSION
3.1 The Series of Sociological Investigations
As was mentioned in section 1.2, in order to achieve participatory design it is important
to carry out social research in such a manner that the persons being studied feel
comfortable and able to express their feelings and opinions. For this reason the site
visits were conducted in the homes of dry-toilet users. In addition, the interviews were
semi-structured so that they could be adapted to the flow of conversation. Finally, the
focus groups were carried out in an informal and familiar environment. The results
were as follows:
Eight site visits: eight locations in Ecuador were visited that each had differing
climatic conditions. Dry toilets with urine separation or with mixed faeces and urine
were both used. A number of installations suffered from ventilation problems, which
led to unfavourable smells and proliferation of flies. Sawdust was often used as a
drying material and used toilet paper was thrown into the toilet (a practise that is not
common in Ecuador). The mix would be left to decompose for a number of months for
it to be converted into compost. The users of the dry toilets generally felt comfortable
using dry toilet technologies, where the resulting fertilizer was used for ornamental

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plants and fruit trees. It is also important to note that every end user had had the dry
toilet installed under his/her own initiative. In this sense they also had no qualms about
mixing the residues of faeces/sawdust/paper/urine in order to produce an optimum
compost and fertilizer.
Twenty-eight semi-structured interviews: the results showed the importance of
cleanliness for both private and public toilets. On average the interviewees used the
toilet four times per day, and tended to change their toilet installation every five to ten
years. There was a consistent preference for white toilets, which were felt to reflect
cleanliness. With regard to negative aspects, special mention was given to the need for
constant cleaning of the toilet, bad smells, the noise made when flushing and the
excessive water needed to do so.
Twelve focus groups: various conclusions were reached. First, that the toilet is a
basic tool of our everyday lives, and as such should always be in optimum working
conditions (with little need for maintenance). Second, cleanliness was seen to be of
fundamental importance, and to this extent white, modern toilets were preferred. Third,
it was considered that the area in which the toilet is found must be clean, with a light
and clear colour scheme to make the user feel at ease. Fourth, there needed to be an
effective system to get rid of the waste products, given that there existed an aversion to
any contact with them (even visual). Finally, in general there was little interest in
knowing about the final destination of the waste products.
3.2 The Initial Prototype
Conventional toilets that are commonly available in the Ecuadorian market tend to be
dual flush, using 4.1 litres for flushing urine, and 6 for solids (Viegener 2014). Given
the results of the sociological investigations, the parameters used for the design of the
initial prototype were to a) maintain the appearance of a conventional toilet, and b) use
the least water possible to flush away the faeces, urine and paper. It is important to
note that the initial prototype developed to date has drastically reduced the water
demand for flushing to but one litre, thanks to a manual suction system. This in turn
opens possibilities to a) recycle water from the hand basin used for washing hands to
recharge for the next toilet flush, and b) reduce the size of the biodigestor that would be
needed in future research, in order to pre-treat the wastewater prior to discharge to
public sewerage systems.
Additionally, a further objective was to minimise the economic impact of changing
toilet systems, and as such enable it to be easily replicated. To this extent it was of
great importance to make use of the existing infrastructures of conventional toilet
installations. The prototype was therefore developed using elements that were easily
accessible in local stores, and which could be installed by the end user him/herself if
necessary.
In Figure 1(a) the first prototype developed is shown, in which a bypass has been
installed that through manual suction generates a vacuum to flush away the waste
products. The system was tested using various fake faeces and toilet paper mixes.
PVC tubing of a 3-inch diameter was used, with a range of heights tested from 90 cm
(in accordance to someone standing) to 54 cm (in accordance with the end user sitting).
The system was successful in flushing away all the waste products. The next
developments of the prototype made were in relation to the water recharge system. The

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objective was that in the same action the toilet would flush, whilst also recharging the
toilet bowl and water deposit in same action. In this manner the toilet was cleaned and
left ready for the next user. This was all achieved whilst maintaining a water demand
per flush of 1 litre. In Figure 1(b) the subsequent prototype developed is shown. In
this case the conventional water cistern is replaced by a compact element that still uses
the water float from the original toilet cistern. A pipe makes use of the air compression
produced above the manual suction piston, pushing water to recharge the toilet bowl.
Finally, in Figure 1(c) a further development of the prototype is shown where water is
flushed directly from above the toilet bowl and the original cistern flapper is used, but
where the cistern is replaced by a transparent container. The advantage of this option is
that the working elements of the toilet flushing system can be clearly seen, which
enables the end users to be conscious of how the toilet functions. For all of the
prototypes, there is the possibility for them to be connected to either the household
water mains or to use recycled water, given that they work independent of water
pressure at the recharge point. To this extent successful trails were made in connecting
the prototypes to the washbasin, thus mitigating the potable water demand from a toilet.
(a) (b) (c)
Figure 1. Manual suction toilet prototypes a, b, and c.

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607
3.3 Initial Testing of the Prototype
This research is in the early stages of carrying out sociological studies to determine the
level of acceptance from the end users. As an initial study to gauge this level of
acceptance, five semi-structured interviews were carried out with members of the
public from a middle-class background. Each person interviewed had previously had
the opportunity to use the first prototype (Figure 1a). In general, the first reaction was
one of some confusion when confronted with the vertical manual suction appendage,
and where it was thought a didactic label might be of use. Otherwise, the prototype
was considered to be a normal toilet. It was natural to pull the manual suction handle
with force, and as such no discharge problems were encountered. It was also clear that
the water demand for toilet flushing had been drastically reduced, which was perceived
to be the main advantage. A disadvantage that was encountered was the noise made
when flushing, due to the sound of the suction mechanism. Finally, it was noted that
used toilet paper could be flushed with the faeces and urine. It was considered unusual
however to do so, given that in in Ecuador it is common practise to throw the used
toilet paper in a specially allocated dustbin adjacent to the toilet. To conclude, it can be
said that the first prototype achieved to: a) drastically reduce the water demand for
flushing; b) maintain the appearance of a conventional toilet; c) use readily available
materials; and d) have an initial positive level of acceptance overall by the end users.
For future research and prototype development, amongst the improvements to be made
it is recommended to: a) make the design easier to comprehend regarding the operation
of the vertical manual suction unit; b) reduce the level of contact the end user has with
the flush mechanism (such as through the incorporation of a pedal-operated system)
which was found to be of importance in the focus groups from Section 3.1.
4 CONCLUSIONS
This research project took on the challenge of looking at how to stop sewage (more
specifically the production of domestic black water), taking the urban sector as its
starting point. The aim is to bring about a mass-change at a micro, or individual level.
To this extent it was put forward to design a toilet prototype in such a manner that the
water demand for flushing was reduced drastically, and as such paving the way for a
micro-biodigestor to be incorporated in the future for the wastewater to be pre-treated
prior to discharge. In order to guarantee that end users accepted the prototype with
open arms, a series of sociological investigations were carried out to determine the
parameters for design. An initial prototype was developed, which used a manual
suction system that brought the water demand down to a mere litre. Additionally, the
prototype is made from a conventional toilet, making use of elements that are readily
available in local stores and without the need for major construction works.
Furthermore, by reducing the water demand to one litre, the doors are opened to use
recycled water from the hand washbasin for toilet flushing. The initial reactions of end
users of the first manual suction prototype were positive overall, where the initial social
study shed light on improvements to be made in the future. Finally, the later prototypes
that were developed did away with the water tank of conventional toilets. This also
reinforced the didactic elements of the toilet, clearly showing the reduced water
demand.

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5 RECOMMENDATIONS FOR FURTHER RESEARCH
Amongst the suggestions for further research, it is recommended to: i) carry out further
development of prototypes, included versions with a mechanized suction system; ii)
develop a branding of the prototypes that leads to a positive first reaction and less
confusion by the end users; iii) carry out an in-depth sociological study, where the
prototypes are installed in a public area such as the Pontificia Universidad Católica of
Ecuador; iv) develop a low-cost, micro biodigestor that can be easily incorporated into
the toilet prototypes, in order to pre-treat the wastewater prior to discharge. Technical
measurements can then be taken of the quality of the water being discharged in order to
guarantee that sewage is indeed eliminated.
Acknowledgments
Special thanks needs to be given to Amelia Tapia, student of Architecture at the Pontificia
Universidad Católica del Ecuador (PUCE), whose work and dedication was invaluable in the
research for this paper. In addition, special acknowledgement needs to be given to Jamie
Radford, Civil Engineer at Mott MacDonald, whose wealth of expertise and availability to
resolve both technical and academic queries was of great importance.
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