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Decentralised wastewater management using constructed wetlands 7

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									                              7 Decentralised wastewater
                                management using
                                constructed wetlands

                   Bhushan Tuladhar, Prajwal Shrestha, and Rajendra Shrestha
                   Environmental Public Health Organisation


Abstract
Environment management is a significant          treatment system in Dulikhel Hospital in 1997.
challenge in developing countries mainly         Since then this has been followed by 13 such
due to lack of strong legislation to control     systems at various institutions (e.g. hospitals,
wastewater and institutional capacity for        schools, university, and monastery) and
integrated planning and management. This         individual households. The system is found to
paper describes the importance of small          be highly effective in removing pollutants such
scale decentralized wastewater treatment         as suspended particles, ammonia-nitrogen,
using reed bed treatment systems (RBTS) in       BOD, COD and pathogens.
Nepal. It shows how public/community
participation can support small scale            With the experience of designing the system
construction work while ensuring checks on       and more than eight years of monitoring and
quality and price of construction. It includes   evaluation of the system, the challenge was to
examples where this system provides good         upscale this technology to a community scale. To
quality, low-cost services.                      overcome this challenge a community scale
                                                 wastewater treatment system was designed for
Environmental Public Health Organisation         Madhaypur Thimi Municipality, a first of its kind
(ENPHO) introduced the system in Nepal           in Nepal. As the local people in Madhaypur
through research and then by designing and       Thimi Municipality showed interest in
constructing a pilot-scale wastewater            wastewater treatment, ENPHO with support of
                                                                                                               7. Decentralised wastewater management using
the Asian Development Bank (ADB), UN-Habitat           population living in urban areas, the rate of
                                                       urbanisation is very high. This rapid urbanisation




                                                                                                               constructed wetlands
and WaterAid Nepal (WAN) constructed a
                                                       is haphazard and so exerts immense pressure on
wastewater treatment system in Sunga area.             the urban environment. Municipal managers often
The treatment plant has the capacity to treat          lack the expertise and resources to deal with this
                                                       issue. As a result, urban sanitation has become a
50m3 of wastewater per day. The local
                                                       major challenge for municipalities and small towns
community has formed a committee for                   in Nepal. Most of the urban and semi-urban areas                87
construction and future O&M of the RBTS. This          of the country rely on on-site sanitation facilities
                                                       such as pit latrines, pour flush toilets and septic
RBTS will set a valuable precedent for other
                                                       tanks. It is estimated that only about 12% of urban
larger systems in other parts of the country as        households are connected to the sewer system
well as systems envisaged under national urban         and wastewater treatment is virtually non-existent.
                                                       Almost all the wastewater is discharged into nearby
development projects in Nepal, such as the
                                                       rivers without any treatment. The total wastewater
Urban Environment Improvement Project.                 produced in the country is estimated to be 370
                                                       million litres per day (MLD). The installed capacity
                                                       of wastewater treatment plants is only 37 MLD
Introduction                                           (10% of total demand) and functioning wastewater
Haphazard disposal of untreated wastewater from        treatment plants account for 17.5 MLD, or 5% of
households as well as institutions and industry is     total demand (Nyachhyon, 2006).
causing severe deterioration of water bodies in
many urban areas in the developing world. Most         The problem of wastewater management is
cities do not have adequate systems for the            particularly severe in Kathmandu Valley, which has
collection and treatment of wastewater and this is     five municipalities and is the largest urban centre
usually not considered to be a priority for            in the country. In the 1980s four wastewater
investment. It is estimated that in developing         treatment plants were built in Kathmandu Valley,
countries, 300 million urban residents, 34% of them    one in Sundarighat, Lalitpur to treat wastewater
in South Asia, have no access to sanitation            from the core areas of Kathmandu, another in
(WaterAid Nepal, 2006). Approximately two-thirds       Balkumari, Lalitpur to treat wastewater from the
of the population in the developing world has no       city of Lalitpur and one each in the Sallaghari and
hygienic means of disposing of excreta and an even     Hanumanghat areas of Bhaktapur. These treatment
greater number lack adequate means of disposing        plants are based on simple lagoon systems, where
of wastewater. This is a major public health risk as   wastewater is treated through natural processes
it can lead to outbreaks of diseases such as           such as sedimentation and biological degradation
diarrhoea, cholera, and typhoid.                       in a series of large lagoons. Although these plants
                                                       are technically very simple with no mechanised
Although urbanisation is a relatively new              parts, they are still not functioning well because of
phenomenon in Nepal, with only about 15% of the        poor operation and maintenance and
                   mismanagement. In 2002 another wastewater              Constructed wetland
                   treatment plant that uses a more complicated           wastewater treatment system
                   oxidation ditch technology has been constructed        Constructed Wetlands (CW) is a biological
Urban sanitation




                   at Guhyeshwori. Although this plant is partially       wastewater treatment technology designed to mimic
                   functioning the cost of operation is very high and     processes found in natural wetland ecosystems.
                   its sustainability is questionable.                    These systems use wetland plants, soils and their
                                                                          associated micro-organisms to remove
88                 Overall the wastewater generated by about two          contaminants from wastewater. Application of
                   million residents in Kathmandu Valley has severely     constructed wetlands for the treatment of municipal,
                   deteriorated the water quality in the Bagmati river,   industrial and agricultural wastewater as well as
                   particularly in the urban stretches. This primarily    storm water started in the 1950s and they have
                   affects the poor people who live near the river        been used in different configurations, scales and
                   and are more exposed to the pollution.                 designs. CWs are receiving increasing worldwide
                                                                          attention for wastewater treatment and recycling
                   The issues that arise from this prevailing position    due to the following major advantages:
                   can be summarised as follows:                             use of natural processes
                      As wastewater management is not a priority             simple construction (can be constructed with
                      for most people or the government, simple              local materials)
                      and cost effective systems are necessary to            simple operation and maintenance
                      ensure that they are managed in a sustainable          cost-effectiveness (low construction and
                      manner.                                                operation costs)
                      A simple and effective operation and                   process stability.
                      maintenance system is essential for operating
                      a wastewater treatment system.                      Research studies have shown that wetland systems
                      Centralised wastewater management systems           have great potential in controlling water pollution
                      are difficult to operate because of the             from domestic, industrial and non-point source
                      difficulties in maintaining the long sewer          contaminants. As it has been widely recognised as
                      networks and treatment plant.                       a simple, effective, reliable and economical
                                                                          technology compared to several other conventional
                   In the late 1990s, in an attempt to try and deal       systems, it can be a useful technology for
                   with some of these difficulties, a new low-cost,       developing countries.
                   low technology process was introduced, by which
                   wetlands are constructed and wastewater treated        There are various types of constructed wetland
                   in them. In this paper, the constructed wetlands       systems for treating wastewater based on the type
                   process is presented, and its implementation in        of plants used, type of media used and flow
                   Nepal described. Some case studies provide             dynamics. The most common type of constructed
                   particular details and then some commentary            wetland system used in Nepal is the sub-surface
                   discusses the challenges involved and the way          flow system, which is also known as the Reed Bed
                   ahead.                                                 Treatment System (RBTS). The basic features of
                                                                                                                          7. Decentralised wastewater management using
RBTS include a bed of uniformly graded sand or        vertically from the top to the bottom of the bed,
gravel with plants such as reeds growing on it. The   and horizontal flow (HF), where the wastewater




                                                                                                                          constructed wetlands
most common type of plant used in Nepal is            flows from one end of the bed to another. VF
Phragmites karka. The depth of media is typically     beds are fed intermittently in a large batch flooding
0.3-0.6 m. Wastewater is evenly distributed on the    the entire surface. After a while the bed drains
bed and flows through it either horizontally or       completely free, allowing air to refill the bed. This
vertically. As the wastewater flows through the bed   kind of feeding leads to good oxygen transfer and
of sand and reeds, it gets treated through natural    hence better removal of pollutants. VF systems                              89
processes like mechanical filtering, chemical         also require less land area (1-2 m2/person) than
transformations and biological consumption of         HF systems, which need 5-10 m 2/person for
pollutants in wastewater. As RBTS uses simple         secondary treatment. A typical VF system can
natural processes, it is effective yet inexpensive
and simple to operate.                                 TABLE 1 Pollutant removal mechanisms in
                                                                  constructed wetlands
As noted above, the RBTS can be of two types:          Wastewater constituents   Removal mechanism

vertical flow (VF), where the wastewater flows         Suspended solids          Sedimentation
                                                                                 Filtration
                                                       Soluble organics          Aerobic microbial degradation
 FIGURE 1 Horizontal flow constructed wetland
                                                                                 Anaerobic microbial degradation
                                                       Phosphorous               Matrix sorption
                                                                                 Plant uptake
                                                       Nitrogen                  Ammonification followed by microbial
                                                                                 nitrification
                                                                                 Denitrification
                                                                                 Plant uptake
                                                                                 Matrix adsorption
                                                                                 Ammonia volatilisation (mostly in SF
                                                                                 system)
                                                       Metals                    Adsorption and cation exchange
                                                                                 Complexation
 FIGURE 2 Vertical flow constructed wetland                                      Precipitation
                                                                                 Plant uptake
                                                                                 Microbial oxidation/reduction
                                                       Pathogens                 Sedimentation
                                                                                 Filtration
                                                                                 Natural die-off
                                                                                 Predation
                                                                                 UV irradiation (SF system)
                                                                                 Excretion of antibiotics from roots of
                                                                                 macrophytes

                                                       Source: Cooper et al., 1996
                   remove the BOD51 of up to 96%; the HF system                                TABLE 2 Constructed Wetlands in Nepal
                   can remove only up to 65%. In recent years, a
                   combination of the two (hybrid system) has become
Urban sanitation




                                                                                                SN Location                         Type of             Treatment
                                                                                                                                    Wastewater          Capacity
                   popular due to the higher efficiency of organic
                                                                                                1 Dhulikhel Hospital                 Hospital           Designed for
                   removal.
                                                                                                                                                        10 m3/day
                                                                                                                                                        but treating
                   Constructed wetlands remove pollutants from
                                                                                                                                                        40 m3/day
90                 wastewater through various physical, chemical and                            2 Private house at Dallu             Grey water         0.5 m3/day
                   biological mechanisms. Some of the main pollutant                            3 Kathmandu Metropolitan City        Septage            40 m3/day
                   removal mechanisms in constructed wetlands are                               4 Malpi International School         Institutional      25 m3/day
                   presented in Table 1.                                                        5 Sushma Koirala Memorial            Hospital           15 m3/day
                                                                                                   Plastic & Reconstructive
                   Constructed wetlands in Nepal                                                   Surgery Hospital
                   In Nepal, the Environment and Public Health                                  6 Kathmandu University               Institutional      40 m3/day

                   Organisation (ENPHO) introduced CW for                                       7 Staff Quarter of Middle            Domestic           26 m3/day
                                                                                                   Marshyangdi Hydro Electric
                   wastewater treatment in 1997 by constructing the
                                                                                                   Power Station
                   first plant at Dhulikhel Hospital. Since then, the
                                                                                                8 ENPHO Laboratory                   Domestic and 1 m3/day
                   interest in this technology has been growing and
                                                                                                                                     laboratory
                   more than a dozen constructed wetlands have been                             9 Kapan Monastery                    Institutional      17 m3/day
                   established for various applications such as the                             10 Septage and Landfill              Septage and Septage:
                   treatment of hospital wastewater, grey water,                                   leachate treatment plant          landfill           75 m3 and
                   septage, landfill leachate, institutional wastewater                                                              leachate           Leachate:
                   and municipal wastewater. The first constructed                                                                                      40 m3
                   wetland treatment plant in Dhulikhel was designed                            11 Sunga                             Municipal           25 m3/day
                   to treat 10 m 3 /day of wastewater but it is
                   successfully treating more than four times that                              TABLE 3       Treatment efficiency of constructed
                                                                                                              wetlands in Nepal
                   amount.
                                                                                                Location              TSS          BOD5          COD          NH4
                   Satisfied with the performance of the treatment                                                    Removal      Removal       Removal      Removal
                                                                                                                      Rate (%)     Rate (%)      Rate (%)     Rate
                   plant, the hospital is now expanding the capacity
                   of the plant. Recently, ENPHO with support from                              Dhulikhel             98.6         98.9          83.7         57
                                                                                                Hospital
                   the Asian Development Bank (ADB), UNHABITAT,
                                                                                                Dallu House           98.6         99.5          96.8         97
                   WaterAid Nepal, Madhyapur Thimi Municipality and
                                                                                                Malpi School          99.1         99.5          99.5         98
                   the local people have established the first
                                                                                                SKM Hospital          98.1         99.2          95.4         98
                   community-based wastewater treatment system in                               Kathmandu             97.9         98.9          99.1         99
                   Nepal using this technology. The Urban Environment                           University
                   Improvement Project (UEIP) which is being                                    ENPHO                 92.1         99.7          97.8         91
                   implemented in eight urban centres with the                                  Source: Shrestha et.al., 2003
                   1
                     Microorganisms placed in contact with organic material will utilize it as a food source. In this utilization, the organic matter will eventually
                   be oxidized to stable end products like carbon dioxide (CO2) and water. The amount of oxygen used in this process is called the
                   Biochemical Oxygen Demand and is considered to be a measure of the organic content of the waste.
                                                                                                                               7. Decentralised wastewater management using
                                                           BOX 1 Dhulikhel Hospital establishes the first
                                                                    constructed wetland in Nepal
                                                           In 1997, Dhulikhel Hospital, a community-based hospital located
assistance ADB is now in the process of constructing
                                                           in Dhulikhel Municipality, set up the first constructed wetland
18 more plants in these towns. A list of operating




                                                                                                                               constructed wetlands
                                                           wastewater treatment system in Nepal to treat all the
CWs in Nepal is given in Table 2.                          wastewater generated in the hospital and ensure that the
                                                           people living around the hospital have access to clean treated
In general, the performance of the CWs has been            water for irrigation. The system was designed by the
excellent. Regular monitoring of the systems shows         Environment and Public Health Organisation (ENPHO) with
high pollutant removal efficiency achieving close          technical support from the University of Natural Resources
to 100% removal of total coliforms and organic             and Applied Life Science (BOKU), in Austria. As this was the
                                                                                                                                        91
pollutants. The pollutant removal rates in six different   first experiment with constructed wetlands in Nepal, the system
                                                           was designed using fairly conservative assumptions and plenty
constructed wetlands are shown in Table 3.
                                                           of safety margin to ensure that the treated water would be of
                                                           acceptable quality. As a result, although the volume of
Challenges                                                 wastewater has increased more than fourfold, the treatment
The experience with constructed wetlands over the          system is still operating effectively today. The treatment system
last decade has clearly shown that this simple and         was originally designed to treat 10 m3 of wastewater per day,
cost effective system can be used to treat various         but it is currently treating about 40 m3 per day as the capacity
types of wastewater ranging from grey water to             of the hospital has increased significantly over the past 10
leachate and septage. However, in spite of the             years.
enormous potential for the use of CW for wastewater
treatment, there are some challenges in the                The constructed wetland at Dhulikhel Hospital has a
promotion of this technology in Nepal, which are           sedimentation tank of 10 m3 capacity for pre-treatment
                                                           followed by a horizontal flow bed then a vertical flow bed. The
as follows:
                                                           horizontal flow bed has a surface area of 140 m2 and is filled
   Due to the lack of awareness of CW technol-
                                                           with 0.6 m sand and gravel. Similarly, the vertical flow bed has
   ogy, it is often difficult to convince people
                                                           an area of 120 m2 and is filled with 1.05 m of sand and gravel.
   that it will work                                       Both the beds are planted with local reeds of the species
   Although the cost of the technology is                  Phragmitis Karka. Initial tests done in 1997 showed that the
   relatively low, it is still difficult to convince       plant was able to remove 98% of total suspended solids
   people to invest in a treatment plant instead           (TSS), 98% of BOD5, 96% of COD and 99.9% of total coliforms.
   of just discharging effluent into the river             It also removed 80% of the ammonia nitrogen and 54% of
   Although CW technology uses locally avail-              phosphate. Follow-up monitoring in 2003 showed that the
   able materials, in some places specified types          plant was still removing 96% of BOD5 and 93% of TSS and
   of sand and gravel or reeds may not be                  COD.

   readily available
                                                           The Hospital as well as the local people are very satisfied with
   This is a low maintenance system, but people
                                                           the performance of the treatment system and the system has
   often think it is a no maintenance system. This
                                                           become a showpiece for the Hospital. Many researchers,
   sometimes leads to carelessness in taking care          students, journalists and other people regularly visit the
   of simple operation and maintenance require-            Hospital to see the constructed wetland in action and learn
   ments such as checking for blockage in the              from it. The Hospital is now in the process of expanding the
   pipes, harvesting the plants etc.                       system.
                   BOX 2 Greywater recycling at the household                           had a population of 47,751 in 2001. As the town was designated
                            level using constructed wetland                             as a municipality only in 1996, major infrastructure developments
                                                                                        like the sewerage system, water supply and road network are
Urban sanitation




                   Dr Roshan Raj Shrestha’s family has a simple house built on
                   about 40 m2 of land in Dallu, ward 15 of Kathmandu                   all still in the planning phase. Sanitation improvement is one of
                   Metropolitan City. At first glance, the house does not look          the most urgent issues the city needs to address, with more
                   much different from the other houses in the neighbourhood.           than 50% of the population still lacking proper sanitation

                   But it is very special because it is the first house in Nepal that   facilities. Though a part of the municipality was connected to
                   treats and recycles its waste water to reduce water                  sewers in the 1990s and the wastewater was supposed to be
92                                                                                      treated through oxidation ponds the work remained incomplete
                   consumption as well as water pollution. In 1998, Dr Shrestha,
                   who pioneered the use of Constructed Wetlands in Nepal,              because of a lack of funds.
                   demonstrated how this technology could be applied to treat
                   grey water at the household level, significantly reducing water      At the request of the Municipality, in 2005, ENPHO, with support

                   demand and water pollution in a cost effective manner. In a          from ADB, UNHABITAT and WaterAid Nepal, initiated the
                   city where the water demand is more than twice the supply            construction of a community-based wastewater treatment plant
                   and the discharge of untreated wastewater has significantly          at Siddhikali, where there was an outfall of a large sewer line

                   deteriorated the local rivers, this system has demonstrated          and wasteland. However, after the construction began, a few
                   how each family can make a difference.                               people raised objections to the plant saying that it would
                                                                                        pollute the local area. Even though a lot of effort was made to

                   The system consists of a 0.5 m3 water tank that has been             convince the local people and they were taken on observation
                   converted into a settlement tank followed by a feeding tank          visits to existing treatment plants, they refused to allow the
                   and a small vertical flow reed bed with an area of only 6 m2.        construction to proceed. This meant that, although most of the

                   The system is good enough to treat all the grey water                local people supported the project, the objections of a few led
                   generated in the house with seven members and the treated            to the failure of the initiative in Siddhikali, thus demonstrating
                   water is used for non-consumptive uses such as flushing,             the need for extensive community mobilisation.

                   gardening and washing. Tests done on the treated water
                   showed that the system was able to remove 97% of the TSS,            Although disappointed by the initial setback, ENPHO and the
                   98% of the BOD5, 98% of ammonia nitrogen and 99.9% of the            municipality were delighted when the people of Sunga invited

                   total coliform. Dr Shrestha points out that the system required      them to build the treatment plant in their neighbourhood
                   an investment of only about Rs. 35,000 (US$500) and the              instead. With the support of the local community, a new system
                   family is able to save about 400 litres of water per day.            was soon designed and built on steep terrain, which was
                                                                                        previously a waste dumping site next to a school at Sunga.
                                                                                        Now the site has a beautiful garden and a model treatment
                                                                                        plant that provides a learning ground for students as well as
                   BOX 3 Community-based wastewater
                                                                                        professionals.
                          management
                   Located in Madhyapur Thimi Municipality, Sunga Tole is the           The constructed wetland at Sunga consists of a coarse screen
                   owner of the first community-based wastewater treatment plant        and a grit chamber for preliminary treatment, a 42 m3 anaerobic
                   in Nepal. Madhyapur Thimi is an old Newar community in the           baffle reactor (ABR) for primary treatment, horizontal flow
                   Kathmandu Valley, which is believed to have been settled in the      followed by vertical flow reed beds for secondary treatment
                   7th century. Situated on elevated land area at an altitude of        and two sludge drying beds for treating sludge. The total area
                   1325 m, the municipality covers a total area of 11.47 sq km and      of the constructed wetland is 375 m2. The treatment plant has
                                                                                                                                           7. Decentralised wastewater management using
a capacity to treat wastewater from 200 households, but it is         generate. But these have to be periodically cleaned, which




                                                                                                                                           constructed wetlands
currently treating wastewater from 80 households. The plant           generates large quantities of highly concentrated faecal
receives an average daily flow of 10 m3 of very high-strength         sludge or septage. Several municipalities and small private
wastewater (average BOD5 of raw wastewater is 1,775 mg/l).            companies operate septic tank cleaning services. However, in
Monitoring of the performance of the system over its first year       the absence of treatment systems, the highly contaminated
of operation shows that it removes organic pollutants highly          sludge is simply dumped in rivers, resulting in heavy pollution.
efficiently (up to 98% TSS, 97% BOD5 and 96% COD). It was
also found that the ABR was very effective in removing organic        Pokhara Sub-Metropolitan City is a major tourist hub in western
pollutants and could remove up to 74% TSS, 77% BOD5 and               Nepal. The city is spread over an area of 55 sq. km. and had
                                                                                                                                                   93
77% COD (Singh et al., 2007).                                         a population of 156,312 in 2001. In 2003, the Asian
                                                                      Development Bank supported Pokhara Environmental
The total cost of the treatment plant was Rs. 2.5 million and         Improvement Programme to build a sanitary landfill site for
the municipality has agreed to provide Rs. 50,000 per year for        the city as part of the Second Tourism Infrastructure
operation and maintenance costs.                                      Development Project. There was a need for a simple and cost
                                                                      effective system for treating the leachate as well as the sludge
The total construction cost of the wetland amounted to NRs.           produced by cleaning of septic tanks in the city. It was estimated
1,800,000 (US$ 26,000) at NRs. 2,900 (US$ 40) per m2 of the           that the city generated 12,000 m3 of faecal sludge and 15,600
wetland. The average O&M cost of the wetland is about NRs.            m3 of municipal waste every year, all of which would be collected
20,000 (US$ 290) per year.                                            and brought to the site. In response, a special wetland was
                                                                      built at the site which consisted of seven sludge drying beds
                                                                      occupying a total area of 1645 m2, where the faecal sludge is
                                                                      initially treated. Each day, sludge is spread on a separate
BOX 4 Treatment of landfill leachate and septage
                                                                      sludge drying bed, resulting in a weekly feeding cycle. The dry
Leachate from landfill sites and septage from septic tanks            sludge is removed and composed while the leachate from the
are known to have very high concentrations of pollutants. As          sludge drying beds, as well as the leachate from the landfill, is
more and more cities construct landfills to manage their              fed into a feeding tank and then to two compartmental
waste, there is a need to treat the leachate they generate.           horizontal flow and four compartmental vertical flow constructed
Often a simple pond is constructed at the bottom of the               wetlands. The plant is designed to treat 35 m3 of septage and
landfill to collect the leachate, which is then either recirculated   40 m3 of landfill leachate per day.
back into the landfill, as in the case of the Sisdol Landfill in
Kathmandu, treated or sent directly to the river. The experience      The treatment plant at Pokhara is the largest constructed
from Sisdol shows that recirculation has not been effective in        wetland in Nepal and it was built at a cost of Rs. 6 million (US$
treating the landfill and direct discharge in the river can           85,700). The effectiveness of the treatment plant has not yet
cause significant pollution downstream.                               been monitored as it is still not fully operational. However, as
                                                                      experiences from other countries have shown that constructed
Septic tanks have been widely promoted as a means of on-              wetlands can be used to treat faecal sludge, the treatment
site sanitation. In urban areas, many houses or institutions          plant built in Pokhara can be a model for other cities if it is
have septic tanks to partially treat the wastewater they              operated properly.
                      Wastewater treatment is not a priority for city                       industrial sites that produce wastewater with
                      governments, private industrialists or                                a high organic content, such as slaughter-
                      institutions, due to the lack of strong                               houses, dairies, breweries and food process-
Urban sanitation




                      legislation and standards.                                            ing industries.
                                                                                            Although constructed wetlands are low
                   The way ahead                                                            maintenance systems people often think they
                   The following steps should be taken to further                           are no maintenance system, resulting in poor
94                 promote decentralised wastewater management                              performance due to simple problems such as
                   through constructed wetlands:                                            clogging of pipes. Therefore, all systems need
                      As this technology is still relatively new, there                     to be regularly monitored and proper
                      is need for continuous research and develop-                          systems for operation and maintenance
                      ment to test the viability of this system under                       should be established.
                      various conditions, including applicability for                       Local governments, as well as international
                      different types of wastewater, effectiveness                          organisations involved in the water and
                      under different climatic conditions, and the                          wastewater sector, should promote this
                      use of different materials and plants. The                            technology by building local capacity and
                      performance of existing constructed wetlands                          scaling up its application.
                      should be carefully monitored and additional                          Professionals and organisations involved in
                      research is required to optimise design and                           promoting CW technology should be given
                      minimise construction cost.                                           opportunities to conduct experiments,
                      Pilot projects should be conducted to                                 improve their skills, network with one another
                      experiment with the use of this technology for                        and disseminate their findings.




                   References
                   Cooper P F, Job G D, Green M B, Shutes R B E (1996) Reed Beds and Constructed Wetland for Wastewater Treatment, WRc Swindon, UK
                   Nyachhyon B L (2006) Service Enhancement and Development of Sanitary Sewarage System in Urban and Semi-Urban Setting in Nepal,
                   Policy Paper 23, prepared for Economic Policy Network, Ministry of Finance (MOF)/HMGN and Asian Development Bank (ADB) Nepal
                   Resident Mission.
                   Rose G D (1999) Community Based Technologies for Domestic Wastewater Treatment and Reuse – options for urban agricultures, Cities
                   Feeding People Report Series
                   Shrestha R R (1999) Application of Constructed Wetlands for Wastewater Treatment in Nepal, Ph.D. Dissertation, Department of Sanitary
                   Engineering and Water Pollution Control, University of Agricultural Sciences Vienna, Austria
                   Shrestha R R, Tuladhar B, Shrestha P (2003) Experiences with Application of Constructed Wetlands for Wastewater Treatment and Reuse in
                   Nepal, ENPHO Magazine, Environment and Public Health Organisation, Kathmandu
                   Singh S, Haberl R, Shrestha R R, Shrestha P and Shrestha R (2007) Performance of the first community-managed constructed wetland in
                   Nepal, Proceedings – International Conference on Sustainable Sanitation, Dongsheng, China
                   Singh S (2007) Constructed Wetlands Design, Construction, Operation and Maintenance Manual, UNHABITAT Water for Asian Cities
                   Programme Nepal, Kathmandu
                   WaterAid Nepal (2006) Total Sanitation in South Asia: the challenges ahead, WaterAid Nepal

								
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