ArticlePDF AvailableLiterature Review

Municipal wastewater treatment in Mexico: Current status and opportunities for employing ecological treatment systems

Authors:

Abstract and Figures

The aim of this paper is to evaluate the current status of municipal wastewater (MWW) treatment in Mexico, as well as to assess opportunities for using ecological treatment systems, such as constructed wetlands. In 2008, Mexico had 2101 MWW treatment plants that treated only 84 m3/s of wastewater (208 m3/s ofMWW were collected in sewer systems). Unfortunately, most treatment plants operate below capacity owing to a lack of maintenance and paucity of properly trained personnel. The main types of treatment systems applied in Mexico are activated sludge and waste stabilization ponds, which treat 44.3% and 18% of the MWW collected, respectively. As in many other developing nations around the world, there is a great need in Mexico for low-cost, low-maintenance wastewater treatment systems that are both economically and environmentally sustainable. In 2005, 24.3 million Mexicans lived in villages of less than 2500 inhabitants and 14.1 million lived in towns with 2500-15,000 inhabitants. An opportunity exists to extend the use of ecological treatment systems to these low population density areas and considerably increase the percentage of MWW that is treated in Mexico. Small-scale and medium-size constructed wetlands have been built successfully in some states, primarily during the past five years. Several barriers need to be overcome to increase the adoption and utilization of ecological wastewater technology in Mexico, including: a lack of knowledge about this technology, scarce technical information in Spanish, and the government's concentration on constructing MWW treatment plants solely in urban areas.
Content may be subject to copyright.
This article was downloaded by: [University of Manitoba Libraries]
On: 05 July 2012, At: 06:32
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Environmental Technology
Publication details, including instructions for authors and subscription information:
http://tandfonline.com/loi/tent20
Municipal wastewater treatment in Mexico: current
status and opportunities for employing ecological
treatment systems
Florentina Zurita a , Eric D. Roy b & John R. White b
a Environmental Quality Laboratory, Centro Universitario de la Ciénega, Universidad de
Guadalajara, Ocotlán, Mexico
b Wetland & Aquatic Biogeochemistry Laboratory, Department of Oceanography and Coastal
Sciences, Louisiana State University, Baton Rouge, USA
Accepted author version posted online: 01 Sep 2011. Version of record first published: 10
Nov 2011
To cite this article: Florentina Zurita, Eric D. Roy & John R. White (2012): Municipal wastewater treatment in Mexico: current
status and opportunities for employing ecological treatment systems, Environmental Technology, 33:10, 1151-1158
To link to this article: http://dx.doi.org/10.1080/09593330.2011.610364
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should
be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,
proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in
connection with or arising out of the use of this material.
Environmental Technology
Vol. 33, No. 10, May 2012, 1151–1158
Municipal wastewater treatment in Mexico: current status and opportunities for
employing ecological treatment systems
Florentina Zuritaa, Eric D. Royband John R. Whiteb
aEnvironmental Quality Laboratory, Centro Universitario de la Ciénega, Universidad de Guadalajara, Ocotlán, Mexico; bWetland &
Aquatic Biogeochemistry Laboratory, Department of Oceanography and Coastal Sciences, Louisiana State University,
Baton Rouge, USA
(Received 25 April 2011; Accepted 21 July 2011)
The aim of this paper is to evaluate the current status of municipal wastewater (MWW) treatment in Mexico, as well as to
assess opportunities for using ecological treatment systems, such as constructed wetlands. In 2008, Mexico had 2101 MWW
treatment plants that treated only 84 m3/s of wastewater (208 m3/s of MWW were collected in sewer systems). Unfortunately,
most treatment plants operate below capacity owing to a lack of maintenance and paucity of properly trained personnel. The
main types of treatment systems applied in Mexico are activated sludge and waste stabilization ponds, which treat 44.3%
and 18% of the MWW collected, respectively. As in many other developing nations around the world, there is a great need
in Mexico for low-cost, low-maintenance wastewater treatment systems that are both economically and environmentally
sustainable. In 2005, 24.3 million Mexicans lived in villages of less than 2500 inhabitants and 14.1 million lived in towns
with 2500–15,000 inhabitants. An opportunity exists to extend the use of ecological treatment systems to these low population
density areas and considerably increase the percentage of MWW that is treated in Mexico. Small-scale and medium-size
constructed wetlands have been built successfully in some states, primarily during the past five years. Several barriers
need to be overcome to increase the adoption and utilization of ecological wastewater technology in Mexico, including: a
lack of knowledge about this technology, scarce technical information in Spanish, and the government’s concentration on
constructing MWW treatment plants solely in urban areas.
Keywords: municipal wastewater; Mexico; ecological treatment systems; constructed wetlands; waste stabilization ponds
1. Introduction
One of the United Nations’ eight Millennium Develop-
ment Goals is to ensure environmental sustainability. As
part of this goal, a target was established in 1990 to halve
the proportion of people without sustainable access to safe
drinking water and basic sanitation by 2015 [1]. Environ-
mental degradation and the impairment of human health
are the two most serious negative impacts of discharg-
ing untreated domestic wastewater into the environment.
Further, pollution of the natural resource base prevents a
large portion of the world’s poor from improving their eco-
nomic condition [2]. The incidence of water-borne disease
is widespread in areas with poor sanitation, which includes
inadequate or absent wastewater treatment. Diarrhoeal dis-
eases remain the leading cause of death from water-related
diseases in children, accounting for 21% of all deaths of
children under five in developing countries [3]. In Mexico,
the mortality rate caused by intestinal diseases in children
under five years old was 9.7% in 2005 (627 cases) [4] and
many cases were related to water pollution. Developing
countries still face a significant challenge with regard to
municipal wastewater (MWW) treatment. In such countries,
Corresponding author. Email: fzurita2001@yahoo.com
only 10% of MWW is treated, and as a consequence most
surface waters and ground waters are degraded to varying
degrees [5]. In addition, because of the increased number
of wastewater collection systems in developing countries,
higher volumes of MWW are collected, and consequently
greater treatment capacity is needed. Although Mexico is
one of the Latin American countries that have recently
increased their number of MWW treatment plants, the total
volume of MWW that is treated remains low.
Municipal wastewater can be treated by different tech-
nologies ranging from elaborate, high energy-consuming
conventional technologies to simple, low-cost ecological
treatment systems [6,7]. Conventional wastewater treat-
ment removes pollutants by processes that demand large
quantities of fossil fuel-derived energy, have short hydraulic
retention times and require the least amount of land area.
Conventional technologies are advantageous for urban
areas or areas where land is expensive. On average, these
treatment systems are expensive to construct, operate and
maintain. In contrast, ecological treatment systems (e.g.
constructed wetlands and waste stabilization ponds) can
require a greater land area, but often have the advantages of
ISSN 0959-3330 print/ISSN 1479-487X online
© 2012 Taylor & Francis
http://dx.doi.org/10.1080/09593330.2011.610364
http://www.tandfonline.com
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
1152 F. Zurita et al.
low operational and maintenance costs, relatively simple
design and high ease of operation [8,9]. Removal of
pollutants in these systems is driven by microbial processes,
sorption and plant uptake [10–12]. Constructed wetlands
appear to be an economic, technical and sustainable alterna-
tive solution for small population communities (up to 3000
inhabitants), especially in rural areas and around big cities.
There are very good experiences in Europe and in Mediter-
ranean countries in the treatment of MWW, stormwater
run-off, industrial wastewater, agricultural run-off and land-
fill leachate [13,14]. Besides providing both secondary
treatment and tertiary/polishing treatment, which is espe-
cially useful when the receiving waters are considered
sensitive or water reuse is an option, constructed wetland
is also a system well accepted by the population and well
integrated in the landscape [15].
To select the most appropriate technology for each spe-
cific case, decision makers should take into account the
advantages and disadvantages of the available technologies
so that the continuous functioning of the wastewater treat-
ment plant can be guaranteed. This is especially important in
developing countries where resources are scarce and other
priorities may divert money and attention away from the
implementation of sound wastewater treatment, disrupting
continuous long-term maintenance and operation when the
costs are high [16].
In this paper, the evolution of municipal wastewater
treatment plants (MWWTP) in Mexico during 2000–2008
is described along with an analysis of the treatment systems
currently applied and current MWW treatment capacity.
Then the applicability of ecological wastewater treatment
systems is reviewed based on experiences in Mexico with
constructed wetlands, focusing on: (1) the increased num-
ber of constructed wetlands in the 32 states of Mexico,
(2) the use of constructed wetlands for on-site treatment
of domestic sewage, and (3) some recent constructions
of small-scale and medium-size constructed wetlands with
non-governmental resources for MWW treatment. Finally,
the challenges and opportunities of expanding the use
of ecological treatment systems in Mexico are discussed.
The information analysed and discussed here was primar-
ily obtained from official sources available in Mexico,
such as the Water National Commission (CONAGUA),
the National Institute of Statistics, and Geography and
Informatics (INEGI). This data was then complemented
with information available in the peer-reviewed scientific
literature.
2. Evolution of municipal wastewater treatment in
Mexico (2000–2008)
In Mexico, the mean flow rates of generated MWW and
MWW collected in sewer systems are 236 and 208 m3/s,
respectively [17]. The number of MWWTPs has increased
from 1018 to 2101duringthe period between 2000 and 2008
(Figure 1). Like Mexico, other Latin American countries
Figure 1. Municipal wastewater treatment plants in Mexico in
2000–2008 [19].
Figure 2. Flow rate of MWW generated, collected and treated
in Mexico during 2000–2008 [19].
including Brazil, Chile, Colombia, Honduras, Nicaragua,
Peru and Uruguay have also recently increased the number
of treatment systems [18]. However, despite the increase
in MWWTPs, the loads of untreated MWW before being
discharged into the environment is still high in Mexico. In
2008, 84 m3/s, or only 36%, of MWW generated was
being treated (Figure 2). During 2000–2008, 222 facili-
ties were not functioning each year, while many plants were
operating with significant deficiencies in their treatment
efficiencies [19].
In 2008, the main treatment systems in use were acti-
vated sludge (454 facilities) and waste stabilization ponds
(677 facilities). These systems were used to treat 46.2%
and 18% of MWW treated in the country (18.6% and 7%
of the collected MWW), respectively. Besides activated
sludge, other conventional electromechanical technologies
were used, including trickling filters, rotating biological
contactors, aerated lagoons and advanced primary systems
(Figure 3). All these systems together processed 77% of
Mexico’s treated MWW. As mentioned previously, these
conventional MWW treatment technologies are expensive
to operate and maintain and require highly trained person-
nel for successful operation. In some cases, the use of such
technologies is necessary because the plants are located in
urban areas where land availability is low and both land
values and the volume of MWW to be treated are high.
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
Environmental Technology 1153
Figure 3. Percentages of collected MWW treated by different
wastewater treatment systems in use in Mexico [20].
An analysis of the treatment systems currently in use
explains, in part, why many MWWTPs are not fully oper-
ational. The gap between installed and fully operational
MWWTPs in Mexico exists because municipalities do not
have sufficient resources to maintain the MWWTPs for
optimal operation [4]. For example, Jalisco State con-
structed 16 new MWWTPs in 2010. In several of the
Jalisco State municipalities where these new MWWTPs
are located, officials have stated that they do not have the
resources to operate them [21]. According to an operator of
Comisión Estatal del Agua-State Water Comission (CEA),
a90L/s modern activated sludge plant generates a monthly
electricity bill of around US$11,500. In addition, the munic-
ipality has to pay trained operators and maintenance costs,
and a significant portion of municipal budgets is needed
to guarantee the continuous operation of a high operat-
ing cost MWWTP. Mexico’s municipalities have several
other important priorities that consume the local budgets
aside from the treatment of MWW, including provision of
potable water, street lighting, solid waste management and
expansion of the sewer system [4]. Therefore, the financial
capability of a municipality to maintain a treatment plant
long-term must be one of the critical factors considered at
the pre-design stage [22].
3. Experience utilizing constructed wetlands in
Mexico
Given the resource constraints that small municipalities
face in Mexico, low-cost, low-energy and low-maintenance
ecological treatment systems are an attractive alternative
to conventional MWWTPs [16]. Waste stabilization ponds
and constructed wetlands have proven to be effective alter-
natives, using natural processes, for treating wastewater
in small communities worldwide, including several in the
United States [12,23,24]. They are capable of removing a
high percentage of pathogenic organisms, compared with
conventional technologies, because of increased retention
times [25]. Waste stabilization ponds are the most widely
used treatment systems in developing countries because of
their low operational and maintenance cost, high efficiency
and high sustainability [22,26]. Although these systems
are in use within Mexico, waste stabilization ponds can
be a source of unpleasant odours and are breeding sites
for mosquitoes that can pose health risks [27]. The dis-
advantages of waste stabilization ponds are overcome in
the implementation of subsurface-flow constructed wet-
lands (SSFCWs) because the water surface is not exposed,
decreasing mosquito breeding and unpleasant odours as
long as the systems are properly maintained and not over-
loaded [25]. They are a good option for the removal of
organics, nitrogen, phosphorous, heavy metals, pesticides,
dyes, PCBs, PAHs and even microbiological load [13,15].
There are many studies on the performance of SSFCWs
for nitrogen removal, since up to 20% of ammonia nitro-
gen and nitrate may be taken up by plants and between
5% and 10% may be removed by non-conventional biolog-
ical pathways [13,15,28]. They are also good systems to
deal with high fluctuation of pollutant loads and hydraulic
loads [14,15]. In rural areas with water scarcity, these sys-
tems are also being used for reclaiming water to be used in
agricultural activities and aquifer recharge [29]. A SSFCW
can be used as an on-site treatment for domestic sewage.
Moreover, wetland plants may be replaced by ornamental
plants in SSFCW without comprising treatment efficiency,
increasing the aesthetics of the system and providing an
economic benefit to the community through the production
of flowers to sell at nearby markets [7,16,30,31]. This strat-
egy recognizes the nutrients contained in wastewater as a
potential resource, an insight of ecological design especially
useful in impoverished communities.
3.1. General evolution of the use of constructed
wetlands in Mexico
Between 2000 and 2008, the number of constructed wet-
land facilities in Mexico increased from 0 to 137. In 2008,
constructed wetlands were used to process only 0.56% of
MWW treated in the country [17,20]. The states with a sig-
nificant number of constructed wetlands are Sinaloa (57),
Oaxaca (38) and Chihuahua (15). Most of the facilities are
small-scale treatment systems utilizing a sedimentation unit
or a septic tank for pretreatment. The flow rate treated by
these systems ranges from 0.2 to 7.0 L/s. Most of the treat-
ment facilities were constructed during the past five years,
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
1154 F. Zurita et al.
and so far there are no detailed published reports on their
performance. In Sinaloa State, due to the combined efforts
of the state and municipal governments, the MWW treat-
ment coverage is currently 91.8% [32], and constructed
wetlands have been utilized to extend coverage in villages
with less than 2500 inhabitants [17,20]. In Chihuahua, to
achieve a MWW treatment coverage of 72%, the primary
technologies utilized were waste stabilization ponds and,
more recently, constructed wetlands. Energy-intensive con-
ventional technologies are used only in the biggest cities
[19,33]. In Oaxaca, one of the poorest states in Mexico,
the MWW treatment coverage is 22% [17,19]. Increasing
the use of constructed wetlands for wastewater treatment is
an appropriate strategy to increase coverage and alleviate
environmental and human health problems associated with
the discharge of untreated wastewater.
3.2. SSFCW for on-site treatment
Subsurface-flow constructed wetlands are currently utilized
in Akumal, Quintana Roo, Mexico, a village with 1200
inhabitants located on the Mexican Caribbean coastline of
the eastern Yucatán Peninsula [34]. The Yucatán penin-
sula is a world-renowned tourism destination [35]. As in
many other parts of Mexico, MWW treatment is lacking
in Akumal and presents a tremendous risk to human health
and the environment [36]. Domestic wastewater treatment
options are limited and currently there are no large-scale,
integrated wastewater treatment systems in the region.
Subsurface-flow constructed wetlands emerged as an appro-
priate technology option because the number of people
served by the municipal sewer system is low and the use of
septic tanks is very common. The construction of SSFCWs
began in the mid-1990s with the support of the Planetary
Coral Reef Foundation and the Ecological Centre of Aku-
mal [37]. Currently in Akumal, there are more than 50
concrete-built wetland systems for domestic and commer-
cial wastewater treatment, with sedimentation pretreatment
in septic tanks. The capacity of the wetlands ranged from
a minimum of approximately one person to a maximum
of 70 people. Of the 38 species recorded as emergent
macrophytes in these SSFCW, only four are conventional
wetland plants; the others are palm trees, coconut trees,
fruit plants (papaya and banana) and ornamental species.
Unfortunately, a recent evaluation of 30 SSFCWs by Varma
[35] revealed that many of these SSFCWs are not func-
tioning properly. As many as 45% of the wetland systems
have odour problems because they are undersized, over-
loaded, poorly vegetated and improperly managed. These
problems occur primarily because the wetlands are smaller
than the required capacity of 5 m2of wetland area per per-
son and almost no maintenance is performed. It has been
shown that wetland maintenance is required from time to
time to prevent hydraulic short-circuiting, and in some cases
accreted organic matter is required to be removed to restore
flow [38]. Many of these poorly performing systems were
designed without taking into consideration the increase in
MWW flow rate that occurs during the peak tourist sea-
son. In other cases, the design used was simply a poorly
executed copy carried out by the property owners. Addi-
tional problems are created by the inclusion of tree species
because their roots may crack the concrete base and walls
of the systems leading to leakage of wastewater that can
contaminate underlying aquifers.
3.3. Medium-size SSFCW constructed with
non-governmental resources
Three treatment wetlands were constructed as part of the
Program for the Environmental Rehabilitation of Lake
Pátzcuaro Basin during 2003–2007. The basin of Lake
Pátzcuaro, located in Central Mexico, is a closed basin
with an area of 929 km2. Lake Pátzcuaro lies at an ele-
vation of 1920 m, covers an area of 126.4 km2and stores
619.4 million cubic metres of fresh water. The towns along
the lake shore are visited by thousands of international and
domestic tourists every year. The pollution in the lake has
increased dramatically during the last 20 years due, in part,
to untreated domestic wastewater discharges generated in
the major towns along the lake shore including Patzcuaro,
Erongaricuaro, Quiroga and Tzintzuntán [39]. Treatment
wetlands were constructed in order to treat a significant
portion of the domestic wastewater generated in the follow-
ing villages: Santa Fe de la Laguna, Quiroga, Cucuchucho,
Tzintzuntzán, Erongarícuaro, [40]. Information used to
design these systems is listed in Table 1.
Table 1. Information used for the design of the constructed
wetland on the Lake Patzcuaro shore1.
Cucuchucho, Santa Fe de la
Data Tzintzuntzán Laguna, Quiroga Erongarícuaro
Flow rate
(L/s)
0.5 3.0 3.33
Population 600 2700 2953
Biochemical
oxygen
demand
(mg/L)
468 414 231
Total
nitrogen
(mg/L)
47 71 60
Total phos-
phorous
(mg/L)
11 13 13
Faecal
coliforms
(MPN/100
mL)
1.7 ×1066.8 ×1073.4 ×108
System total
area (Ha)
0.6 1.5 1.16
1Water quality parameters are for influent.
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
Environmental Technology 1155
Each whole treatment system includes several stages:
pretreatment (screening and sand channel), primary
treatment (sedimentation unit), secondary treatment (con-
structed wetlands and maturation ponds) and polishing
treatment (constructed wetlands). Over this sequence, the
removal efficiency for pollutants ranged from 85% for total
phosphorus to 99.99% for faecal coliforms.
The construction of treatment wetlands on Lake
Patzcuaro’s shore was made possible through the partici-
pation of the Mexican Institute for Water Technology, who
initiated the project by obtaining funds from the non-profit
Gonzalo Arrionte Foundation and providing expertise in
system design [40]. The Mexican Institute for Water Tech-
nology worked closely with people in the local community.
The communities donated the land required for the project
and actively participated by providing labour during the
construction. Three more constructed wetlands are planned
to be built in the near future along the lake shore. This
example of treatment plant construction, supported by non-
governmental resources and including active participation
of both an academic institution and the community, presents
a potentially successful model for increasing the utilization
of constructed wetlands in other communities throughout
Mexico.
4. Challenges of and opportunities for using
ecological treatment systems
The total population in Mexico in 2005 was over103 mil-
lion [34]. The population is spread throughout the county in
both urban and rural areas. We define urban areas as places
with more than 2500 residents, whereas rural areas are com-
munities with fewer than 2500 residents. The population
distribution is shown in Table 2.
Given that the main disadvantage of using constructed
wetlands for treatment of wastewater is the more extensive
land area requirement in comparison with conventional sys-
tems, these treatment systems are appropriate technologies
for small villages located in rural areas in Mexico where
land availability is generally high and costs are low. The
widespread use of this technology is critical in rural areas,
where the sewer system coverage has increased from 37%
to 58% in 2000–2005, thereby generating larger quantities
of collected MWW requiring treatment [17]. Although the
use of low-cost constructed wetland treatment technology
is not new in Mexico, implementation still remains low for
a number of reasons, several of which are discussed below.
Table 2. Population distribution in Mexico, in rural and urban
areas [34].
Community size % of population Number of inhabitants
<2500 23.5 24,266,896
2500–15000 13.7 14,147,084
>15000 62.8 64,849,408
4.1. Lack of knowledge about constructed wetlands
amongst wastewater treatment entrepreneurs
Most Mexican companies dedicated to wastewater treat-
ment plant construction in Mexico promote conventional
technologies, primarily because their knowledge of and
experience with constructed wetlands is limited. In addi-
tion, the economic benefits they can obtain with con-
ventional technologies are greater in comparison to those
they could obtain with the lower-cost constructed wetland
technologies. This factor has delayed the widespread use
of constructed wetlands in Mexico. The options offered
to municipalities are almost always conventional, elec-
tromechanical technologies (personal experience of the
authors).
Fortunately, this situation seems to be slowly chang-
ing and the number of constructed wetlands has increased
recently in some states, as we previously documented. One
way to accelerate the process of adoption of constructed
wetlands for wastewater treatment is through more active
participation of research centres and academic institutions
working in concert with small entrepreneurs during the
design and pollutant-removal monitoring stages, such as the
aforementioned example by the Mexican Institute for Water
Technology in Central Mexico. In this sense, it is impor-
tant to adopt the most common design criteria in SSFCW
construction (Table 3) in order to guarantee their proper
function. In addition, it is recommended that the influent
concentration of COD and TSS does not exceed 400 mg/L
and 100 mg/L, respectively, to minimize bed clogging [29].
4.2. Lack of a basic detailed design manual for
potential users
Most information on constructed wetlands is written in
English, and potential users of this technology, such as vil-
lagers, municipal authorities and small-scale entrepreneurs,
may not possess a high proficiency in the English lan-
guage. According to the experience in Akumal, the use
of constructed wetlands as an on-site treatment technol-
ogy failed because the residents did not have an easy-to-
understand, detailed manual to guide them step by step
on the design, construction, operation and maintenance
of the constructed wetland. This language barrier may be
Table 3. Common design criteria for SSFCWs [14,29].
Criteria
Specific surface area 3–6 m2/p.e.
Organic loading rate 2–12 g BOD5/(m2·d) or
5–20 g COD/(m2·d)
Solids loading rate 5–12 g TSS/(m2·d)
Hydraulic loading rate 2–20 cm/d
Hydraulic retention time 5–14d
Faecal coliforms (MPN/100 mL) 1.7 ×106
System total area (Ha) 0.6
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
1156 F. Zurita et al.
overcome by creating and distributing handbooks written
in Spanish and by the translation of well-recognized books
about constructed wetlands. Again, this work may be done
through the work of national and international academic
institutions.
4.3. Low environmental awareness in Mexico, with
emphasis on rural areas
Concern for the conservation and improvement of the envi-
ronment is scarce in regions where the education level of
the general population is low and poverty remains high.
After beginning school at the age of six, the average Mex-
ican attends school for 8.1 years, dropping out before the
age 14 [34]. The situation is generally worse in rural areas.
Although only one quarter of Mexico’s population lives
in rural areas, they account for 60.7% of the country’s
extremely poor and 46.1% of the moderately poor inhab-
itants [41]. Consequently, poorer communities are more
concerned about the most basic survival issues (food, hous-
ing, medical care) than diverting their attention and time
on environmental issues, and therefore their demands are
focused on basic services. As a result, it is still difficult
in many regions to convince people to invest additional
resources (time, space, money) in a wastewater treatment
plant as opposed to discharging untreated effluent into rivers
and other surface waters [7]. Therefore, it is imperative to
quantify and provide the community with information on
the benefits of wastewater treatment in order to encourage
public attention and support. In a broad sense, the con-
struction MWWTPs in rural areas requires considerable
investment in engaging the people of these communities.
4.4. Involvement of poor communities in WWTP
projects
It is also possible that people in Mexico’s villages and
small towns never realize that they have a WWTP. A field
assessment of 10 of the 20 SSFCWs located in the Oax-
aca Valley demonstrated how this common situation can
lead to poorly maintained treatment plants. Ten SSFCWs
were constructed by national and state water agencies in
communities representing three distinct types: peri-urban
communities located within close proximity to Oaxaca City,
regional towns (>5000 inhabitants) and rural communities.
In some cases, neither the communities nor the local gov-
ernments were aware that they had treatment plants that
needed to be maintained. This implies that there was a lack
of ownership of these wastewater treatment plants [42]. In
order to foster a sense of ownership in the WWTP, the
community should be informed and involved in all phases
of the project in order to guarantee the continued success
of the project. Local community involvement has been
essential in the success of other water-related appropriate
technology projects in developing countries. For example,
community involvement with the non-profit Tarun Bharat
Sangh has driven the resurgence of traditional ‘johads’ in
Rajasthan, India, for rainwater harvesting [2,43]. There,
local villagers contribute labour and local materials, par-
ticipate in planning, determine annual repairs and develop
local laws to protect the watershed of the johad. These
efforts have attracted international attention and, as of 2002,
almost 2500 water conservation structures have been built
in over 500 villages, dramatically increasing groundwater
resources and assisting in withstanding flood events that
previously washed away numerous engineered structures.
A similar effort, where ecological engineering is coupled
with active community engagement, is needed to success-
fully establish constructed wetlands in Mexico’s regional
towns and rural communities.
4.5. Emphasis on domestic wastewater treatment in
urban areas
In Mexico, one of the central aims of the current National
Water Program is to treat wastewater, and the goal is to
reach a MWW treatment coverage of 100% by 2020 [17].
The federal government has promoted MWW treatment
in urban areas through the Program of Drinking Water,
Sewer Service and Sanitation in Urban Areas (APAZU)
since 1990 [44]. Through this program, up to 50% of the
construction costs of a MWWTP in urban areas can be
supported by federal resources. Therefore, the coverage
of MWWTPs has been extended mainly to medium-sized
cities or urban localities because the use of ecological
treatment systems is not feasible owing to the require-
ment for a large land area. Additionally, some modern
wastewater treatment plants have been constructed in large
cities [17,35]. Unlike in urban areas, the availability of
land is a minor problem in small villages (<2500 inhab-
itants), where 24.3 million of Mexico’s inhabitants live,
and in those areas classified as urban (2500–15,000 inhabi-
tants) where another 14.1 million people live. The strategy
followed by the Chihuahua State reserves the use of con-
ventional technologies for large cities only and implements
waste stabilization ponds and constructed wetlands in the
smaller municipalities. This strategy should be replicated
throughout the country because it focuses on the optimal
use of resources and increases the potential distribution
of MWWTPs in smaller communities that require less
technical and monetary support for successful operation.
5. Conclusions
From 2000 to 2008, a significant increase in the distribu-
tion of MWWTPs has occurred in Mexico. However, only
36% of Mexico’s MWW is treated before being discharged
directly into surface waters. Aquatic ecosystem degrada-
tion and negative human health impacts are common in
many places throughout the country. The strategy used for
expanding the use of MWWTPs in Mexico is currently inef-
ficient because most of the systems utilized are conventional
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
Environmental Technology 1157
electromechanical technologies that require highly trained
personnel and are expensive to construct, operate and main-
tain. Hundreds of these plants are operating under capacity
or are not functioning at all because of the inability of
municipalities to finance their continued operation and
maintenance. While these technologies are indispensable
in big cities, their use should be avoided in rural areas with
low population and resource density. Low-cost, low-energy
and low-maintenance ecological treatment systems, such
as constructed wetlands, are appropriate technologies for
almost one quarter of the total population, who live in small
villages (with less than 2500 inhabitants) as well as for those
communities with 2500–15000 inhabitants. Constructed
wetlands generally do not require any electricity or expen-
sive infrastructure, thus providing a substantial savings over
the long term. They can also be used as on-site treatment in
places where sewer services are limited. There are a num-
ber of factors that have prevented or slowed the adoption of
this low-cost wastewater treatment alternative in Mexico.
Two of the most relevant barriers are the general lack of
knowledge about the beneficial use of constructed wetlands
amongst wastewater treatment entrepreneurs (which leads
them to offer only conventional technologies to munici-
palities) and the lack of uncomplicated, detailed manuals,
written in Spanish, on constructed wetland construction and
maintenance. To overcome these barriers to successful uti-
lization of constructed wetlands, much greater participation
of research centres and academic institutions – in a manner
that actively engages local communities in the design and
maintenance process – is crucial to continue to improve the
quality of life for all people in Mexico.
References
[1] United Nations Development Group, Indicators for mon-
itoring the Millennium Development Goals: Definitions,
rationale, concepts, and sources, United Nations, New York,
2003. Available at http://unstats.un.org/unsd/publication/
seriesf/Seriesf_95E.pdf.
[2] A. Agarwal and S. Narain, Community and household
water management: The key to environmental regeneration
and poverty alleviation,inInstitutionalizing Common Pool
Resources, D.K. Marothia, ed., Concept Publishing, New
Delhi, 2002, pp. 115–151.
[3] United Nations Educational, Scientific and Cultural Organi-
zation (UNESCO) and United Nations World Water Assess-
ment Programme (WWAP), Water: A shared responsibility.
The United Nations world water development report 2.
UNESCO-WWAP, Barcelona, 2006.
[4] J. De Anda and H. Shear, Challenges facing municipal
wastewater treatment in Mexico, Public Works Manage.
Policy 12 (2008), pp. 590–598.
[5] K. Reynolds, El tratamiento de las aguas residuales
en Latinoamérica. Identificación del problema, Agua
Latinoamericana, September/October 2002 (In Spanish).
Available at http://www.agualatinoamerica.com/docs/PDF/
DeLaLaveSepOct02.pdf.
[6] B. Guterstam and J. Todd, Ecological engineering for
wastewater treatment and its application in New England
and Sweden, Ambio 19 (1990), pp. 173–175.
[7] F. Zurita, J. De Anda, and M.A. Belmont, Treatment of
domestic wastewater and production of commercial flow-
ers in vertical and horizontal subsurface-flow constructed
wetlands, Ecol. Eng. 35 (2009), pp. 861–869.
[8] H. Brix, How ‘green’ are aquaculture, constructed wetlands
and conventional wastewater treatment systems? Water Sci.
Technol. 40 (3) (1999), pp. 45–50.
[9] M.E. Arias and M.T. Brown, Feasibility of using constructed
treatment wetlands for municipal wastewater treatment in
the Bogotá Savannah, Columbia, Ecol. Eng. 35 (2009),
pp. 1070–1078.
[10] K.R. Reddy and E.M. D’Angelo, Biogeochemical indi-
cators to evaluate pollutant removal efficiency in con-
structed wetlands, Water Sci. Technol. 35 (5) (1997),
pp. 1–10.
[11] J.L. Conkle, C. Lattao, J.R. White, and R.L. Cook, Com-
petitive sorption and desorption behavior for three flouro-
quinolone antibiotics in a wastewater treatment wetland soil,
Chemosphere 80 (2010), pp. 1353–1359.
[12] L.M. Malecki-Brown, J.R. White, and K.R. Reddy, Soil bio-
geochemical characteristics influenced by alum application
in a municipal wastewater treatment wetland, J. Environ.
Qual. 36 (2007), pp. 1904–1913.
[13] A. Albuquerque, J. Oliveira, S. Semitela, and L. Ama-
ral, Influence of bed media characteristics on ammo-
nia and nitrate removal in shallow horizontal subsurface
flow constructed wetlands, Bioresour. Technol. 100 (2009),
pp. 6269–6277.
[14] A. Albuquerque, M. Arendacz, M. Gajewska, H. Obarska-
Pempkowiak, P. Randerson, and P. Kowalik, Removal of
organic matter and nitrogen in an horizontal subsurface flow
(HSSF) constructed wetland under transient loads, Water
Sci. Technol. 60 (2009), pp. 1677–1682.
[15] J. Vymazal, Horizontal sub-surface flow and hybrid con-
structed wetlands systems for wastewater treatment, Ecol.
Eng. 25 (2005), pp. 478–490.
[16] F. Zurita, M.A. Belmont, J. De Anda, and J.R. White, Seeking
a way to promote the use of constructed wetlands for domes-
tic wastewater treatment in developing countries, Water Sci.
Technol. 63 (2011), pp. 654–659.
[17] Comisión Nacional del Agua (CONAGUA), Estadísticas
del Agua en México, edición 2010, Secretaría de Medio
Ambiente y Recursos Naturales, Mexico, 2010 (In Spanish).
[18] J.L. Machinea, A.Bárcena, and A. León, The Millennium
Development Goals: A Latin American and Caribbean
Perspective, United Nations Publications, Santiago, Chile,
2005.
[19] Comisión Nacional del Agua (CONAGUA), Inventario
nacional de plantas municipales de potabilización y
tratamiento de aguas residuales en operación, Secretaría de
Medio Ambiente y Recursos Naturales, Mexico, 2009 (In
Spanish).
[20] Comisión Nacional del Agua (CONAGUA), Situación del
subsector agua potable, alcantarillado y saneamiento, Sec-
retaría de Medio Ambiente y Recursos Naturales, Mexico,
2009 (In Spanish).
[21] Comisión Estatal del Agua (CEA) Jalisco, La CEA
entregó simultáneamente 16 Plantas de Tratamiento de
Aguas Residuales, 2010 (In Spanish). Available at http://
www.ceajalisco.gob.mx/notas/nota_16plantas.html (accessed
May 2010).
[22] M. Peña and D. Mara, Waste Stabilization Ponds, IRC
International Water and Sanitation Centre, The Hague,
The Netherlands, 2004. Available at http://www.irc.nl/page/
14622.
[23] J.L. Conkle, J.R. White, and C.D. Metcalfe, Removal of
pharmaceutically active compounds in a lagoon wetland
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
1158 F. Zurita et al.
wastewater treatment system, Chemosphere 73 (2008),
pp. 1741–1748.
[24] J.W. Day, A.Y. Arancibia, W.J. Mitsch, A.L. Lara-Dominguez,
J.N. Day, J.Y. Ko, R. Lane, J. Lindsey, and D.Z. Lomeli,
Using ecotechnology to address water quality and wetland
habitat loss problems in the Mississippi basin: A hierarchical
approach, Biotechnol. Adv. 22 (2003), pp. 135–159.
[25] S. Kayombo, T.S.A. Mbwette, J.H.Y. Katima, N.Ladegaard,
and S.E. Jørgensen, Waste stabilization ponds and con-
structed wetlands design manual, United Nations Envi-
ronment Programme (UNEP)-International Environmental
Technology Centre (IETC) and Danish International
Development Agency (Danida), 2005. Available at
http://www.unep.or.jp/Ietc/Publications/Water_Sanitation/
ponds_and_wetlands/Design_Manual.pdf.
[26] A. Kivaisi, The potential for constructed wetlands for
wastewater treatment and reuse in developing countries: A
review, Ecol. Eng. 16 (2001), pp. 545–560.
[27] J.H.J. Ensink, M. Mukhtar, W. Van der Hoek, and F. Kon-
radsen, Simple intervention to reduce mosquito breeding in
waste stabilization ponds, Trans. R. Soc. Trop. Med. Hyg.
101 (2007), pp. 1143–1146.
[28] W. Tao and J. Wang, Effects of vegetation, limestone
and aeration on nitratation, anammox and denitrifica-
tion in wetland treatment systems, Ecol. Eng. 35 (2009),
pp. 836–842.
[29] H. Marecos do Monte and A. Albuquerque, Analysis of con-
structed wetland performance for irrigation reuse, Water
Sci. Technol. 61 (2010), pp. 1699–1705.
[30] D. Konnerup and H. Brix, Nitrogen nutrition of Canna
indica: Effects of ammonium versus nitrate on growth,
biomass allocation, photosynthesis, nitrate reductase
activity and N uptake rates, Aquat. Bot. 92 (2008),
pp. 142–148.
[31] D. Konnerup, T. Koottatep, and H. Brix, Treatment of
domestic wastewater in tropical, subsurface flow constructed
wetlands planted with Canna and Heliconia, Ecol. Eng.
35(2009), pp. 248–257.
[32] J.M. Pineda, Logra Sinaloa susmetas en limpieza de
aguasresiduales, Centro Mexicano de Derecho Ambiental,
2010 (In Spanish). Available at http://sintesis.cemda.org.mx/
artman2/publish/agua/Logra_Sinaloa_sus_metas_en_limpi-
eza_de_aguas_residuales.php.
[33] Secretaría de Medio Ambiente y Recursos Naturales
(SEMARNAT)-CONAGUA, Conagua y el gobierno de
Chihuahua ponen en marcha nuevas obras hidráulicas en
Ciudad Juárez, Comunicado de Prensa No. 083-10, Ciudad
Juárez, Chihuahua, Mexico, 2010 (In Spanish). Available
at http://www.bnamericas.com/cgi-bin/getresearch?report=
146009.pdf&documento=1069601&idioma=E&login=.
[34] Instituto Nacional de Estadística, Geografía e Informática
(INEGI), II Conteo de Población y Vivienda 2005,México y
sus Municipios, INEGI, Aguascalientes, Mexico, 2008 (In
Spanish).
[35] S. Varma, Environmental studies of constructed wetlands
in Akumal, Mexico: New comparisons of geotechnical and
botanical parameters, M.Sc. thesis, George Mason Univer-
sity, 2009. Available at http://u2.gmu.edu:8080/bitstream/
1920/5694/1/Varma_Sheela.pdf.
[36] M.P.S. Krekeler, P. Probst, M. Smasonov, C.M. Tselepis, and
W. Bates, Investigations of subsurface flow constructed wet-
lands and associated geomaterial resources in the Akumal
and Reforma regions, Quintana Roo, Mexico, Environ. Geol.
53 (2007), pp. 709–726.
[37] M. Nelson, Wetland systems for bioregenerative reclamation
of wastewater: From closed systems to developing countries,
Life Support Biosphere Sci. 5 (1998), pp. 357–369.
[38] H. Wang, J.W. Jawitz, J.R. White, C.J. Martinez, and M.D.
Sees, Rejuvenating the largest municipal treatment wetland
in Florida, Ecol. Eng. 26 (2006), pp. 132–146.
[39] M.M. Carro, J.I. Dávila, A.G. Balandra, R.H. López, R.H.
Delgadillo, J.S. Chávez, and L.B. Inclán, Importance of dif-
fuse pollution control in the Patzcuaro Lake Basin in Mexico,
Water Sci. Technol. 58 (2008), pp. 2179–2186.
[40] C.E. González and A. Rivas, Humedales artificiales
para el tratamiento de las aguas residuales gener-
adas en áreas rurales ribereñas al lago de Pátzcuaro,
Tláloc 43 (2008), pp. 8–13 (In Spanish). Available at
http://www.amh.org.mx/tlaloc/TLALOC_41.pdf.
[41] World Bank, A study of rural poverty in Mexico, World
Bank, 2005, Available at http://siteresources.worldbank.org/
INTMEXICO/Resources/A_Study_of_Rural_Poverty_in_
Mexico.pdf.
[42] P. Haase, A field assessment of wastewater treatment facil-
ities in the Oaxaca Valley, Mexico, M.Sc. thesis, Humboldt
State University, 2010.
[43] J. Vanclay, R. Prabhu, and F. Sinclair, Realizing Commu-
nity Futures: A Practical Guide to Harnessing Natural
Resources, Earthscan, London, 2006.
[44] Comisión Nacional del Agua (CONAGUA), Programa
de Agua Potable, Alcantarillado y Saneamiento en Zonas
Urbanas (APAZU), CONAGUA, Mexico, 2009 (In Spanish).
Available at http://www.conagua.gob.mx/CONAGUA07/
Noticias/MANUAL_APAZU_2009.pdf.
Downloaded by [University of Manitoba Libraries] at 06:32 05 July 2012
... In contrast, solutions like constructed wetlands are less adopted, being society's engagement one of the barriers that prevent CWs' implementation (Fig. 5). To date, approximately half of the Mexican states have no constructed wetlands installed (Zurita et al., 2012). Research about CW has been available for the last 20 years, with academia being the principal promoter of these technologies in M exico. ...
... Research about CW has been available for the last 20 years, with academia being the principal promoter of these technologies in M exico. Most publications refer only to experimental cases and less to full-scale applications; and focus on domestic wastewater, such as the CPlantae WWTP, and do not address the issue of agriculture or industrial wastewater (Zurita et al., 2012). ...
... Even though CPlantae's current clients are highly engaged in sustainability topics, the innovators had encountered antipathy during fieldwork as water and sanitation themes are seen as a government responsibility. Other barriers are summarized in the following figure, including the abandonment due to limited availability of funds for pilot stages or a short-term approach to projects that fails to address long-term maintenance and operation (García-García et al., 2016;Zurita et al., 2012). Research on appropriate technology, technology adoption models (Molina-Maturano et al., 2019) or consumer research may improve the understanding of the adoption and the upscaling of constructed wetlands (García-García et al., 2016), like the study by Revollo-Fern andez (2016) on the willingness to buy and pay for agroecological products from Xochimilco, a wetland in M exico. ...
Article
Due to their potential economic, social and environmental benefits, frugal innovations have gained the attention of firms, policy-makers, and researchers, particularly with respect to the needs of communities at the Bottom of the Pyramid. However, there is a lack of comprehensive systematic approaches to evaluate their impact on sustainable development certainly in geographical regions with limited available data. Hence, this study evaluated the sustainability of two latent frugal innovations in México and the motivation of their innovators, specifically of an ecological wastewater treatment plant and a rainwater harvesting system. Applying a case study methodology, the two cases were investigated using an online questionnaire, expert interviews, document analysis, and a recently developed sustainability evaluation framework. The results showed that frugal innovations are related to the concepts of catalytic and social innovation, sharing motivations by innovators and innovations’ features. In addition, the results of the sustainability assessment by experts, which is rooted in the Sustainable Development Goals showed that both cases did not infringe any of the 17 goals, had a neutral impact on 39% and 51% of the SDGs and positively impacted all three dimensions of sustainability with a slight emphasis on social sustainability (with 36% and 21% of the overall impact). The present study proved that the framework is a useful and accessible tool for diverse actors, including innovators aiming to communicate the impact of their solutions or identifying risks/alerts at scaling-up phases. While the explorative nature and the limited number of cases investigated limits the scope for generalisation, the in-depth study of the selected cases of water innovation in their specific contexts nevertheless produced valuable insights for further research, especially regarding the integrated investigation of social, frugal and catalytic perspectives on innovation in Central and Latin America, and the quantification of impacts on sustainable development using comprehensive research approaches.
... Compared to the existing solutions within the specific context of Mexico (Section 2.3), the WWTP features are in line with the FI definition (Table 5-2). (Zurita et al., 2012). ...
... Cheaper investment, operating, and maintenance costs (US EPA, 2000;Zurita et al., 2012). ...
... Existing WWTPs are only cost-effective in urban areas (Zurita et al., 2012) but no standard solutions for rural areas where around 25% of the Mexican population lives. ...
... In Mexico, the treatment of domestic wastewater in rural areas is very low in comparison to urban areas. For example, 9 out of 10 municipalities with more than 500 000 inhabitants have at least one wastewater treatment plant in operation, while only 1833 rural communities (of 47,233 localities) with a population of 100 to 2,499 inhabitants have a system of wastewater treatment (Zurita et al., 2012;Zamora et al., 2019;Cáñez-Cota, 2022). In addition, in rural areas is common the generation of agro industrial effluents that are not treated. ...
Article
Full-text available
The aim of this study was to evaluate the development and effect of Heliconia latispatha in pilot-scale constructed wetlands (CWs) for the treatment of pig wastewater mixed with domestic wastewater, using PET waste as filter medium, in a tropical climate. Six cells filled with rough recycled PET waste were used; 3 operated with vegetation and 3 without vegetation and the study lasted 8 months. The results showed an excellent development of H. latisphata under the flooded conditions, reaching a level of development similar to the level of development in commercial soil crops. The good development of the plant was reflected in the remarkable increase in plant height, stem thickness, number of plants and inflorescences. In addition, the presence of H. latisphata significantly influenced the removal of contaminants (p<0.05) such as COD (chemical oxygen demand), TN (total nitrogen), TP (total phosphorus) and TC (total coliforms), reaching higher removals by 7.8%, 8.5%, 18% and 13.7%, respectively, with respect to the systems without vegetation. The production of H. latispatha flowers and the good removal of pollutants from the influent make the system a viable alternative for the production and commercialization of H. latispatha under tropical climates while at the same time the wastewater is treated.
... In some cases, capacity for these water services exists. Still, high operational costs (mainly due to electricity) prevent municipalities or water service agencies from operating at full capacity (Zurita et al. 2012). The average electricity consumption for municipal water services in Durango was 0.58 kWh/m 3 and about 70% goes to supply potable water and 30% to sewage treatment (CONUEE 2018). ...
Article
Full-text available
This study develops a novel mathematical modelling framework for biomass combined heat and power systems (CHP) that links biomass and process characteristics to sustainability assessment of the life cycle. A total of twenty-nine indicators for the process (four-indicators), economic (five-indicators), environmental (eight-indicators) and social global (five-indicators) and local (seven-indicators) aspects have been analysed for sustainability. These are technological: biomass throughput, electricity and steam generations and CHP efficiency; economic: internal rate of return, capital, operating and feedstock costs and cost of production; environmental: global warming, fossil, land and water use, acidification, urban smog, eutrophication and ecotoxicity potentials; social (global): labour rights and decent work, health & safety, human rights, governance and community infrastructure; social (local): total forest land, direct/indirect jobs, gender equality and energy-water-sanitation access for communities, from biomass characteristics (carbon and hydrogen contents), energy demands and economic parameters. This paper applies the developed methodology to a case study in Mexico. From 12.47 kt/year forestry residue, 1 MWe is generated with an associated low-pressure steam generation of 50 kt/year, at the cost of production of $0.023/kWh. This makes the energy provision “affordable and clean” for marginalised/poor communities (the UN Sustainable Development Goals, SDG7). Bioenergy can curb > 90% of the greenhouse gas emissions and primary energy use, 6 kt CO 2 eq and 74 TJ annually. Bioenergy reduces other environmental impacts considerably, water consumption, acidification and eutrophication by 87–53%, and urban smog and ecotoxicity by 29–18%. Bioenergy can improve all five social themes in the Central American cluster countries. In addition to the SDG7, the forestry-based bioenergy system can also achieve the SDG6: "clean water and sanitation for all". Graphical abstract
... Electricity is required for water pumping during extraction and distribution, potabilization and sewage treatment systems. In some cases, capacity for these water services exists, but high operational costs (mainly due to the cost of electricity) prevents municipalities or water service agencies from operating at full capacity (Zurita et al. 2012 to clean water and sanitation in these municipalities. Thus, the electricity supply is ...
Preprint
Full-text available
This study develops a novel mathematical modelling framework for biomass combined heat and power systems (CHP) linking physicochemical/thermodynamic characteristics and life cycle sustainability. A total of twenty-nine indicators for the process (4), economic (5), environmental (8) and social global (5) and local (7) aspects have been analysed for sustainability. These are biomass throughput, electricity and steam generations and CHP efficiency; internal rate of return, capital, operating and feedstock costs and cost of production; global warming, fossil, land and water use, acidification, urban smog, eutrophication and ecotoxicity potentials; labour rights & decent work, health & safety, human rights, governance and community infrastructure; total forest land, direct/indirect jobs, gender equality and energy-water-sanitation access for communities, from biomass characteristics (carbon and hydrogen contents), energy demands and economic parameters. The model is disseminated as an open-web-resource https://tesarrec.web.app/sustainability/chp. In a case study approach, from 12.47 kt/year forestry residue, 1 MWe is generated with an associated low-pressure steam generation of 50 kt/year, at a cost of production of $0.023/kWh, making “affordable and clean energy” (the UN Sustainable Development Goals, SDG7) for marginalised/poor communities. Bioenergy can curb >90% greenhouse gas emissions and primary energy, 6 kt CO 2 eq and 74 TJ annually, 87-53% water consumption, acidification and eutrophication, and 29-18% urban smog and ecotoxicity, compared to fossil-based counterpart. All five social themes in the Central American cluster countries can be improved by bioenergy. In addition to SDG7, SDG6: "clean water and sanitation for all" can be delivered by forestry-based bioenergy system.
... According to United Nations Sustainable Development Goal Number Six, a substantial increase in water treatment and reuse must be accomplished by 2030 to significantly reduce water scarcity worldwide and to protect the natural environment [1]. Centralized wastewater treatment plants (WWTPs) involve higher maintenance and operational costs than decentralized WWTPs, which are also easier to operate [2]. Anaerobic bioreactors (ARs) and constructed wetlands (CWs) are treatment stages that are commonly used in decentralized systems [3]; these units are classified as passive technologies, since they require low energy consumption and maintenance and operational costs [3,4]. ...
Article
Full-text available
Septic tanks (STs), up-flow anaerobic filters (UAFs), and horizontal-flow constructed wetlands (HFCWs) are cost-effective wastewater treatment technologies especially efficient in tropical and sub-tropical regions. In this study, the bacterial communities within a decentralized wastewater treatment plant (WWTP) comprising a ST, a UAF, and a HFCW were analyzed using high-throughput sequencing of the V3–V4 region of the 16S rRNA gene. Bacterial diversity and its spatial variation were analyzed at the phylum and family level, and principal component analysis (PCA) was applied to nitrogen- and organic-matter-degrading families. The highest percentage of nitrogen removal was seen in the HFCW (28% of total Kjeldahl nitrogen, TKN, and 31% of NH3-N), and our results suggest that families such as Rhodocyclaceae (denitrifying bacteria), Nitrospiraceae (nitrifying bacteria), and Rhodospirillaceae (sulfur-oxidizing bacteria) contribute to such removal. The highest percentage of organic matter removal was seen in the UAF unit (40% of biological oxygen demand, BOD5, and 37% of chemical oxygen demand, COD), where organic-matter-degrading bacteria such as the Ruminococcaceae, Clostridiaceae, Lachnospiraceae, and Syntrophaceae families were identified. Redundancy analysis demonstrated that bacterial communities in the HFCW were more tolerant to physicochemical changes, while those in the ST and the UAF were highly influenced by dissolved oxygen and temperature. Also, pollutant removal pathways carried out by specific bacterial families and microbial interactions were elucidated. This study provides a detailed description of the bacterial communities present in a decentralized WWTP located in a subtropical region.
Article
Full-text available
In this systematic review we explore the forces that encourage or hinder the adoption of wastewater treatment and/or management technology. Our literature search uncovered 37 sources that discuss these issues. Retrieved sources were then subjected to qualitative synthesis. We adopted a systems-theory perspective in analyzing the qualitative data and provide insights into the interaction between the political environment and societal and organizational systems. Our findings indicate that sustainable change can best be achieved through understanding the interaction between systems and their actual capability to meet the needs of related systems. Societal-level systems emerge as having the possibility to influence the political environment as well as organizations.
Article
The objective of the present study was to evaluate the performance of a domestic wastewater treatment system based on hybrid constructed wetlands (CWs) under tropical climate. Moreover, the effect of different recirculation strategies particularly on nitrogen removal was also evaluated, including an analysis of nitrogen balance. The system was composed of a septic tank (pre-treatment), a horizontal subsurface flow and a vertical subsurface flow CWs. Three systems were analyzed: with the ornamental species Sagittaria lancifolia, the cattail Typha dominguensis and without vegetation as control. Evapotranspiration in the CWs was monitored during the warmest period of the year. First, the three systems were operated in serial mode evaluating two contact times of 2 d and 4 d. The three hybrid CWs were able to remove more than 92% of organic matter (COD, BOD5 and TOC), 88% of TSS and 99% (equivalent to 4.5 log10 units) of pathogens (Total Coliforms and Escherichia coli), regardless of plant selection and contact time. However, applying a contact time of 4 d resulted in higher removal of pathogens. Concerning nutrients removal, the combination of a contact time of 4 d and vegetation was required to achieve removal efficiencies over 66% for nitrogen and 90% for phosphorus. Finally, two recirculation strategies (RS) using a contact time of 4 d were evaluated in order to enhance nitrogen removal: RS1 (to the horizontal units) and RS2 (to the septic tank). The results yielded removal efficiencies similar to those obtained during serial operation in the case of organic matter (COD and BOD5) and phosphorus regardless of the RS applied. However, the removal of TSS decreased with RS2 as expected, due to the new load of solids coming from the septic tank. Nevertheless, nitrogen removal was increased over 85% in the hybrid CWs with vegetation, satisfactorily achieving system optimization. The highest nitrogen removal efficiency (≈ 97%) was obtained with the combination of RS2 and the plant species T. dominguensis. However, the use of the ornamental species S. lancifolia was not discarded since it provides an additional aesthetic benefit.
Article
Full-text available
A mess of plastic It is not clear what strategies will be most effective in mitigating harm from the global problem of plastic pollution. Borrelle et al. and Lau et al. discuss possible solutions and their impacts. Both groups found that substantial reductions in plastic-waste generation can be made in the coming decades with immediate, concerted, and vigorous action, but even in the best case scenario, huge quantities of plastic will still accumulate in the environment. Science , this issue p. 1515 , p. 1455
Article
Full-text available
The review aims to report the state-of-the-art constructed wetlands (CW) in the Latin America and Caribbean (LAC) region not limited to national and local conditions. The aim is with a broader view, to bring updated and sufficient information, to facilitate the use of the CW technology in the different countries of LAC. Thus, 520 experiences extracted from the 169 reviewed documents in 20 countries were analyzed. According to the data, horizontal subsurface flow wetlands are the most reported CW in the region (62%), the second most common CW technology in the region is free water surface CW (17%), then vertical flow systems (9%), followed by intensified constructed wetlands (8%), and finally French systems (4%). The performance for nutrient removal is analyzed, finding that the mean of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorous (TP) removal efficiencies varies from 65% to 83%, 55% to 72%, and 30% to 84%, respectively. The results suggest a generally good performance for COD and TN removal, but a low performance for TP removal. Regarding plant species used for CWs, 114 different plant species were reported, being until now the most extensive report about plant species used in CWs in the LAC region.
Article
Full-text available
The Orlando Easterly Wetland (OEW), one of the largest constructed wetlands for the treatment of wastewater in Florida, started operation in 1987 for the reduction of nutrient loads in tertiary treated domestic wastewater produced by the City of Orlando. The wetland has performed better than design expectations, but phosphorus removal effectiveness experienced some seasonal declines beginning with the winter of 1999. Subsequent studies indicated that the OEW treatment capacity was hindered by inefficient phosphorus removal in the upstream cells of one of three flow trains. Therefore, rejuvenating management activities were initiated on these cells in 2002. The management included the removal of plants and organic top sediments, site grading in the interior of the cells, construction of baffles and islands, and re-vegetation. This study evaluates the improvement in hydraulic and phosphorus removal performance realized from the wetland modifications. Improvement of hydraulic performance was evaluated based on tracer tests, and improvement of phosphorus removal performance was evaluated based on episodic spatially distributed water samples as well as model prediction. The results showed that both the hydraulic efficiency and the phosphorus removal effectiveness of the rejuvenated wetland were significantly increased. However, the wetland has likely re-entered a start-up phase and long-term observation will be necessary to determine eventual steady-state conditions.
Article
Globally, more than 1 billion people lack access to a safe water supply, and more than 2.4 billion people lack access to proper wastewater treatment. This situation leads to repeated outbreaks of preventable diseases. In 2005 in Mexico, only 28.2% of municipal wastewaters received any kind of treatment. This article examines the present and projected situation with respect to wastewater treatment and the implications of these trends on water supply and on public health. Possible technical solutions are also analyzed so that the country can increase the ratio between treated and discharged municipal wastewaters.
Article
Wetlands support several aerobic and anaerobic biogeochemical processes that regulate removal/retention of pollutants, which has encouraged the intentional use of wetlands for pollutant abatement. The purpose of this paper is to present a brief review of key processes regulating pollutant removal and identify potential indicators that can be measured to evaluate treatment efficiency. Carbon and toxic organic compound removal efficiency can be determined by measuring soil or water oxygen demand, microbial biomass, soil Eh and pH. Similarly, nitrate removal can be predicted by dissolved organic C and microbial biomass. Phosphorus retention can be described by the availability of reactive Fe and Al in acid soils and Ca and Mg in alkaline soils. Relationships between soil processes and indicators are useful tools to transfer mechanistic information between diverse types of wetland treatment systems.
Article
The main water bodies in the Bogotá Savannah have been seriously polluted due to the mismanagement of domestic, agricultural, and industrial wastewater. While there are a number of wastewater treatment facilities in the region, most do not function properly. There is a great need for inexpensive and sustainable wastewater treatment systems that are not technologically sophisticated and that do not require intensive management. The main goal of this study was to quantify the performance and sustainability of treatment wetlands and existing wastewater treatment systems in this region. Using data from the literature, a treatment wetland model was developed, which focused on pollutant removal. The modeled performance was compared to a system of waste stabilization ponds and a sequencing batch reactor. The three systems were subject to cost analysis and an emergy evaluation, leading to the assessment of indicators of cost-benefit for comparison. The economic analysis suggested that the net annual cost of the treatment wetland was US$ 14,672, compared to US$ 14,201 for the stabilization ponds and US$ 54,887 for the batch reactor. The emergy evaluations show that the ponds have the lowest annual emergy flow (6.65+16sej/yr), followed by the constructed wetland (2.88E+17sej/yr) and the batch reactor (8.86E+17sej/yr). These results were combined to estimate treatment ratios (contaminants removed per lifetime cost, and contaminants removed per total emergy), cost ratios (cost per volume of water, annual cost per capita, and construction cost per capita), and emergy ratios (treatment yield, renewable emergy, lifetime emprice, construction emprice, non-renewable emergy, empower density, environmental loading, total emergy per volume of water, and emergy per capita).
Article
The effects of inorganic nitrogen (N) source (NH4+, NO3− or both) on growth, biomass allocation, photosynthesis, N uptake rate, nitrate reductase activity and mineral composition of Canna indica were studied in hydroponic culture. The relative growth rates (0.05–0.06gg−1d−1), biomass allocation and plant morphology of C. indica were indifferent to N nutrition. However, NH4+ fed plants had higher concentrations of N in the tissues, lower concentrations of mineral cations and higher contents of chlorophylls in the leaves compared to NO3− fed plants suggesting a slight advantage of NH4+ nutrition. The NO3− fed plants had lower light-saturated rates of photosynthesis (22.5μmolm−2s−1) than NH4+ and NH4+/NO3− fed plants (24.4–25.6μmolm−2s−1) when expressed per unit leaf area, but similar rates when expressed on a chlorophyll basis. Maximum uptake rates (Vmax) of NO3− did not differ between treatments (24–35μmolNg−1rootDWh−1), but Vmax for NH4+ was highest in NH4+ fed plants (81μmolNg−1rootDWh−1), intermediate in the NH4NO3 fed plants (52μmolNg−1rootDWh−1), and lowest in the NO3− fed plants (28μmolNg−1rootDWh−1). Nitrate reductase activity (NRA) was highest in leaves and was induced by NO3− in the culture solutions corresponding to the pattern seen in fast growing terrestrial species. Plants fed with only NO3− had high NRA (22 and 8μmolNO2−g−1DWh−1 in leaves and roots, respectively) whereas NRA in NH4+ fed plants was close to zero. Plants supplied with both forms of N had intermediate NRA suggesting that C. indica takes up and assimilate NO3− in the presence of NH4+. Our results show that C. indica is relatively indifferent to inorganic N source, which together with its high growth rate contributes to explain the occurrence of this species in flooded wetland soils as well as on terrestrial soils. Furthermore, it is concluded that C. indica is suitable for use in different types of constructed wetlands.
Article
The Orlando Easterly Wetland (OEW), one of the largest constructed wetlands for the treatment of wastewater in Florida, started operation in 1987 for the reduction of nutrient loads in tertiary treated domestic wastewater produced by the City of Orlando. The wetland has performed better than design expectations, but phosphorus removal effectiveness experienced some seasonal declines beginning with the winter of 1999. Subsequent studies indicated that the OEW treatment capacity was hindered by inefficient phosphorus removal in the upstream cells of one of three flow trains. Therefore, rejuvenating management activities were initiated on these cells in 2002. The management included the removal of plants and organic top sediments, site grading in the interior of the cells, construction of baffles and islands, and re-vegetation. This study evaluates the improvement in hydraulic and phosphorus removal performance realized from the wetland modifications. Improvement of hydraulic performance was evaluated based on tracer tests, and improvement of phosphorus removal performance was evaluated based on episodic spatially distributed water samples as well as model prediction. The results showed that both the hydraulic efficiency and the phosphorus removal effectiveness of the rejuvenated wetland were significantly increased. However, the wetland has likely re-entered a start-up phase and long-term observation will be necessary to determine eventual steady-state conditions. (C) 2005 Elsevier B.V. All rights reserved.
Article
In developing countries, the use of non-conventional plant species as emergent plants in constructed wetlands may add economic benefits besides treating wastewater. In this work, the use of four commercial-valuable ornamental species (Zantedeschia aethiopica, Strelitzia reginae, Anturium andreanum and Agapanthus africanus) was investigated in two types of subsurface wetlands for domestic wastewater treatment. Severalwater quality parameterswere evaluated at the inlet and outlets of a pilot-scale system. Physical measurements were used to evaluate and compare the development of the ornamental plants under two patterns of flow in subsurface wetlands. The results for pollutant removal were significantly higher in the vertical subsurface-flow constructed wetlands (VFCW) for most pollutants. The average removalswere more than 80% for BOD and COD; 50.6% for Org-N; 72.2% for NH4 +, 50% for Total-P and 96.9% for TC. Only two pollutants were removed in statistically higher percentages in the horizontal subsurface-flow constructed wetlands (HFCW) (NO3 −, 47.7% and TSS, 82%). The pollutant removal efficiencies were similar to the results obtained in many studies with conventional macrophytes. Most ornamental plants survived the 12-month period of experimentation and their development depended on the type of constructedwetland theywere planted. Z. aethiopica looked healthier and produced around 60 flowers in the HFCW. The other three species developed better in the VFCW, although A. andreanum died during the winter. S. reginae produced healthier flowers (and more) and bigger leaves and A. Agapanthus produced more leaves and more lasting flowers. This suggests that it is possible to produce commercial flowers in constructedwetlands without reducing the efficiency of the treatment system.
Article
The term 'green' is nowadays widely used (and misused) in connection with many types of technologies. If a technology is 'green' it usually means that the technology requires less non-renewable energy sources than other alternatives. However, other parameters need to be considered as well, such as sustainability, recycling potential, treatment capacity and potential, conservation of ecosystems, etc. In this paper the energy requirements and nutrient recycling potential of constructed wetlands and wastewater aquaculture facilities are compared with that of conventional wastewater treatment technologies. The energy requirements of constructed wetlands are very low, but if significant reuse of nutrients is included (aquaculture), the energy requirements increase significantly and usually beyond the energy equivalent of the biomass produced. This is especially true in cold temperate climates where the aquaculture systems need to be housed in heated greenhouses and artificial light must be provided to secure operation throughout the year. In countries where fresh water itself is a limiting resource and where the economic capability may limit the use of artificial fertilisers, the reuse potential of wastewater may be more important. The potential for sustainable cropping of the plant biomass is excellent in tropical wetlands as the plants have a high productivity and a continuous growing season. In order to evaluate in more detail the 'greenness' of the different wastewater treatment technologies, the life-cycle approach might be applied. However, because constructed wetlands, besides the water quality improvement function, perform a multitude of other functions such as biodiversity, habitat, climatic, hydrological and public use functions, methodologies need to be developed to evaluate these functions and to weigh them in relation to the water quality issues. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.
Article
Subsurface flow constructed wetlands in the village of Akumal, Quintana Roo, Mexico were surveyed to determine the general status of the wetland systems and provide baseline information for long term monitoring and further study. Twenty subsurface flow wetlands were surveyed and common problems observed in the systems were overloading, poor plant cover, odor, and no secondary containment. Bulk mineral composition of aggregate from two subsurface flow constructed wetlands was determined to consist solely of calcite using bulk powder X-ray diffraction. Some soil structure is developed in the aggregate and aggregate levels in wetlands drop at an estimated rate between 3 and 10cm/year for overloaded wetlands owing to dissolution. Mineral composition from fresh aggregate samples commonly is a mixture of calcite and aragonite. Trace amounts of Pb, Zn, Co, and Cr were observed in fresh aggregate. Coefficients of permeability (k) varied from 0.006 to 0.027cm/s with an average values being 0.016cm/s. Grain size analysis of fresh aggregate samples indicates there are unimodal and multimodal size distributions in the samples with modes in the coarse and fine sand being common. Investigations of other geologic media from the Reforma region indicate that a dolomite with minor amounts of Fe-oxide and palygorskite is abundant and may be a better aggregate source that the current materials used. A Ca-montmorillonite bed was identified in the Reforma region as well and this unit is suitable to serve as a clay liner to prevent leaks for new and existing wetland systems. These newly discovered geologic resources should aid in the improvement of subsurface flow constructed wetlands in the region. Although problems do exist in these wetlands with respect to design, these systems represent a successful implementation of constructed wetlands at a community level in developing regions.