Vertical Flow CW

Compiled by:
Eawag (Swiss Federal Institute of Aquatic Science and Technology), Beat Stauffer (seecon international gmbh) , Dorothee Spuhler (seecon international gmbh)
Adapted from:
TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014)

Executive Summary

A vertical flow constructed wetland (vertical flow CW) is a planted filter bed for secondary or tertiary treatment of wastewater (e.g. greywater or blackwater) that is drained at the bottom. Pre-treated Wastewater (e.g. from a septic tank or an Imhoff tank) is poured or dosed onto the surface from above using a mechanical dosing system. The water flows vertically down through the filter matrix to the bottom of the basin where it is collected in a drainage pipe. The water is treated by a combination of biological and physical processes. The filtered water of a well functioning constructed wetland can be used for irrigation, aquaculture, groundwater recharge or is discharged in surface water. To design a vertical flow constructed wetland, expert knowledge is recommended. They are relatively inexpensive to build where land is affordable and can be maintained by the local community. The important difference between a vertical and horizontal wetland is not simply the direction of the flow path, but rather the aerobic conditions.

In Out

Blackwater, Greywater, Brownwater

Fertigation Water, Treated Water

Introduction

Constructed wetlands are secondary treatment facilities for household (blackwater or greywater, in some cases also brownwater) and/or biodegredable municipal or industrial wastewater. Constructed wetlands are a treatment step of DEWATS systems and they can even be used as a tertiary treatment system for polishing after activated sludge or trickling filter plants (HOFFMANN et al. 2010). How the vertical flow CW works: By intermittently dosing the wetland (4 to 10 times a day), the filter goes through stages of being saturated and unsaturated, and, accordingly, different phases of aerobic and anaerobic conditions. During a flush phase, the wastewater percolates down through the unsaturated bed. As the bed drains, air is drawn into it and the oxygen has time to diffuse through the porous media.

The filter media acts as a filter for removing solids, a fixed surface upon which bacteria can attach and a base for the vegetation. The top layer is planted and the vegetation is allowed to develop deep, wide roots, which permeate the filter media. The vegetation transfers a small amount of oxygen to the root zone so that aerobic bacteria can colonize the area and degrade organics. However, the primary role of vegetation is to maintain permeability in the filter and provide habitat for microorganisms. Nutrients and organic material are absorbed and degraded by the dense microbial populations. By forcing the organisms into a starvation phase between dosing phases, excessive biomass growth can be decreased and porosity increased.

TILLEY et al 2014 Schematic of the Vertical Flow Constructed Wetland

Schematic of the Vertical Flow Constructed Wetland. Source: Tilley et al. (2014)

The plants grown in the wetland may be used for composting or biogas production (see also composting small scale, composting large scale or anaerobic digestion). Effluents, if they correspond to the WHO guidelines (see also WHO 2006: Guidelines for the safe use of wastewater excreta and greywater Volume I, Volume II, Volume III and Volume IV) may be used for fertigation.

Basically, there are three different types of constructed wetlands (CWs). They are classified according to the water flow regime as:

 

 

These three types of CWs may be combined with each other in hybrid constructed wetlands in order to exploit the specific advantages of the different systems.

One of the main advantages of CWs is that they are natural systems and thus not require chemicals, energy or high-tech infrastructure. Moreover, there are suited to be combined with aquaculture or sustainable agriculture (irrigation).

Design Considerations 

The vertical flow constructed wetland can be designed as a shallow excavation or as an above ground construction. Clogging is a common problem. Therefore, the influent should be well settled in a primary treatment stage before flowing into the wetland. This separates solid materials (e.g. faeces or kitchen slop) as well as grease or oil from the liquid. Depending on the situation, there are several possibilities such as grease trap, septic tank, anaerobic baffled reactor, imhoff tank, biogas settler, UASB reactor, or compost filter (HOFFMANN et al. 2010). The design and size of the wetland is dependent on hydraulic and organic loads. Generally, a surface area of about 1 to 3 m2 per person equivalent is required. Each filter should have an impermeable liner and an effluent collection system. A ventilation pipe connected to the drainage system can contribute to aerobic conditions in the filter. In cold climates (annual average < 10°C), an area of 4 m2/p.e. is necessary. In warmer climates (annual average > 20°C), 1.2 m2/p.e. is enough, if the filter is designed correctly (HOFFMANN et al. 2010).

Operation

In vertical filter beds wastewater is intermittently applied (either by pump or self-acting syphon device) onto the surface and then drains vertically down through the filter layers towards a drainage system at the bottom. In some cases, the distribution pipes are covered with gravel to avoid open water puddles. The treatment process is characterised by intermittent short-term loading intervals (4 to 12 doses per day) and long resting periods during which the wastewater percolates through the unsaturated substrate, and the surface dries out. The intermittent batch loading enhances the oxygen transfer and leads to high aerobic degradation activities. Therefore, vertical filters always need pumps or at least siphon pulse loading, whereas horizontal flow constructed wetlands can be operated without pumps (if topography allows). The treatment process of constructed wetlands is based on a number of biological and physical processes (adsorption, precipitation, filtration, nitrification, predation, decomposition, etc.) (HOFFMANN et al. 2010).

Substrate (Adapted from HOFFMANN et al. 2010)

Structurally, there is a layer of gravel for drainage (a minimum of 20 cm), followed by layers of sand and gravel.

  HOFFMANN et al. (2010)

Left: Vertical flow filter during construction in Brazil (lined with polythene liner), drains are being covered with gravel. Right: Vertical flows filter in Peru during filling with sand. Source: HOFFMANN et al. (2010)

The provision of a suitably permeable substrate in relation to the hydraulic and organic loading is the most critical design parameter of subsurface flow constructed wetlands. Most treatment problem occur when the permeability is not adequately chosen for the applied load.The drainage pipes at the base are covered with gravel. On top of this gravel layer, there is a sand layer (40-80 cm thick) which contains the actual filter bed of the subsurface flow CW. On top of the sand layer there is another gravel layer (about 10 cm), in order to avoid water accumulating on the surface. The top gravel layer does not contribute to the filtering process.

Design recommendations regarding the substrate to be used in subsurface flow filters are:

 

 

The recommended grain size distribution for the substrate is shown in the graphic below.

The substrate should not contain loam, silt or other fine material, nor should it consist of material with sharp edges (the figure below illustrates the properties of suitable sand).

 HOFFMANN et al. (2010)

It is important to pay attention to grain size. The most important aspect is a sufficiently coarse grain size. The d10, which corresponds to the grain size where 10 % of the grains are smaller than that grain size, should be between 0.1 mm and 0.4 mm. Having the choice it is recommended to have a d10 closer to 0.4 mm. The material should not have a d10 coarser than 0.4 mm as the filtration in the filter is affected. The steeper the sieving curves the better. Source: HOFFMANN et al. (2010)

What kind of filter material should be used depends on the local conditions and the experiences of the design engineer. HOFFMANN et al. (2010) recommend sand as a substrate, because in their point of view it is the most suitable substrate for the application of subsurface flow CWs for wastewater or greywater treatment in developing countries.

Plants

Depending on the climate, Phragmites australis (reed), Typha sp. (cattails) or Echinochloa pyramidalis are common plant options (TILLEY et al. 2008). Bamboo or papyrus should also be possible, but have not been investigated yet (HOFFMANN et al. 2010). More possible plants and their characteristics can be found in HOFFMANN et al. 2010. Testing may be required to determine the suitability of locally available plants with the specific wastewater.

            B. STAUFFER (2010)

A vertical constructed wetland in Switzerland vegetated with Phragmites australis. Source: B. STAUFFER (2010)

Plants are aesthetically pleasant and serve as a habitat for wildlife. Dead plant material is a natural insulations layer and protects the filter during winter in cold climates. Furthermore, the vegetation transfers oxygen to the filter zone and plants and its roots provide an appropriate habitat for microbiological growth in the root zone. But the most essential function of the vegetation, i.e. the roots system is to maintain the permeability in the filter (HOFFMANN et al. 2010 and TILLEY et al. 2008). Due to the high oxygen supply into the filter, the rates of nitrification are higher than in a horizontal flow filter (MOREL and DIENER 2006). Due to good oxygen transfer, vertical flow wetlands have the ability to nitrify, but denitrification is limited. In order to create a nitrification-denitrification treatment train, this technology can be combined with a Free-Water Surface or Horizontal Flow Wetland.

Health Aspects/Acceptance

Pathogen removal is accomplished by natural decay, predation by higher organisms, and filtration. The risk of mosquito breeding is low since there is no standing water. The system is generally aesthetic and can be integrated into wild areas or parklands. Care should be taken to ensure that people do not come in contact with the influent because of the risk of infection.

Greywater, which has been treated in subsurface flow constructed wetlands generally meets the standards for pathogen levels for safe discharge to the environment without further treatment. In case of domestic wastewater, the situation could be different and for safety reasons, disinfection (by tertiary treatment) might be necessary, depending on the intended reuse application (HOFFMANN et al. 2010).

The biggest health risk arises from settled wastewater in the pre-treatment facility. This should be considered during inspections and emptying. A proper emptying process (human powered or motorised) can decrease the health risks (TILLEY et al. 2008). After that, also sludge must be treated correctly, for example in drying beds or composting facilities.

Costs Considerations

The capital costs of constructed wetlands are highly dependent on the costs of sand since the bed has to be filled with sand; and on the cost of land (HOFFMANN et al. 2010). Financial decisions on treatment processes should not primarily be made on capital costs, but on net present value or whole-of-life costs, which includes the annual costs for operation and maintenance (HOFFMANN et al. 2010).

Compared to other intensive (high-rate) aerobic treatment options (e.g. activated sludge), constructed wetlands are natural systems, which work extensively. That means treatment may require more land and time, but you can save costs because of lower operation, which requires no or only little electrical energy and operators can be trained people from the community (low-skilled people). It means also that there is no need for sophisticated equipment, expensive spare parts or chemicals (GAUSS 2008). According to HOFFMANN et al. (2010) constructed wetlands are usually cheaper to build than high-rate aerobic plants but for larger plants, they are usually more expensive in terms of capital costs.

For large-scale treatment plants of more than 10 000 PE in areas where land is available cheaply, free-surface-flow constructed wetlands and waste stabilisation ponds have lower capital costs than subsurface-flow constructed wetlands (horizontal and vertical) due to the high amounts of sand and gravel fill required for the bed of the sub-surface flow constructed wetland. Plants and liners may substantially add to the costs if they are unavailable locally (EAWAG/SANDEC 2008). Moreover, design and construction of subsurface-flow constructed wetland require skilled technical staff. However, the cost may be reduced if the material is acquired locally.

Operation & Maintenance

In general the O&M requirements for constructed wetlands are relatively simple (no high-tech appliances or chemical additives), allowing community organisations or a private, small-scale entrepreneur to manage the system after adequate capacity building and with technical support (GAUSS 2008). However, a CW will require maintenance for the duration of its life. This aspect is frequently overlooked in decision-making processes.

During the first growing season, it is important to remove weeds that can compete with the planted wetland vegetation. Distribution pipes should be cleaned once a year to remove sludge and biofilm that might block the holes. With time, the gravel will become clogged by accumulated solids and bacterial film. Resting intervals may restore the hydraulic conductivity of the bed. If this does not help, the accumulated material has to be removed and clogged parts of the filter material replaced. Maintenance activities should focus on ensuring that primary treatment is effective at reducing the concentration of solids in the wastewater before it enters the wetland. Maintenance should also ensure that trees do not grow in the area as the roots can harm the liner.

A very critical situation occurs when the filter smells like “foul eggs”. This is an indicator for anaerobic conditions. In this case the filter should be rested and the loads must be readjusted (HOFFMANN et al. 2010). It needs to be controlled regularly whether pre-treatment facilities work properly, and they have to be emptied frequently and sludge must be discharged correctly (see human-powered emptying and transport and motorised emptying and transport).

Vertical systems require more technical expertise than other wetland technologies such as waste stabilisation ponds, surface flow CWs or [1847-horizontal CWs (HOFFMANN et al. 2010).

At a Glance

Working Principle

Pre-treated grey- or blackwater is applied intermittently to a planted filter surface, percolates through the unsaturated filter substrate where physical, biological and chemical processes purify the water. The treated wastewater is collected in a drainage network (adapted from MOREL and DIENER 2006).

Capacity/Adequacy

It can be applied for single households or small communities as a secondary or tertiary treatment facility of grey- or blackwater. Effluent can be reused for irrigation or is discharged into surface water (MOREL and DIENER 2006).

Performance

BOD = 75 to 90%; TSS = 65 to 85%; TN < 60%; TP < 35%; FC ≤ 2 to 3 log; MBAS ~ 90%; (adapted from: MOREL & DIENER 2006)

Costs

The capital costs of constructed wetlands are dependent on the costs of sand and gravel and also on the cost of land required for the CW. The operation and maintenance costs are very low (MOREL and DIENER 2006).

Self-help Compatibility

O&M by trained labourers, most of construction material locally available, except filter substrate could be a problem. Construction needs expert design. Electricity pumps may be necessary.

O&M

Emptying of pre-settled sludge, removal of unwanted vegetation, cleaning of inlet/outlet systems.

Reliability

Clogging of the filter bed is the main risk of this system, but treatment performance is satisfactory.

Main strength

Efficient removal of suspended and dissolved organic matter, nutrients and pathogens; no wastewater above ground level and therefore no odour nuisance; plants have a landscaping and ornamental purpose (MOREL and DIENER 2006).

Main weakness

Even distribution on a filter bed requires a well-functioning pressure distribution with pump or siphon. Uneven distribution causes clogging zones and plug flows with reduced treatment performance; high quality filter material is not always available and expensive; expertise required for design, construction and monitoring (MOREL and DIENER 2006).

Applicability

The vertical flow constructed wetland is a good treatment for communities that have primary treatment (e.g., Septic Tanks, septic tanks, anaerobic baffled reactors, imhoff tanks, biogas settlers, UASB reactors, or compost filter ) but are looking to achieve a higher quality effluent. Because of the mechanical dosing system, this technology is most appropriate where trained maintenance staff, constant power supply, and spare parts are available. Since vertical flow constructed wetlands are able to nitrify, they can be an appropriate technology in the treatment process for wastewater with high ammonium concentrations. Vertical flow constructed wetlands are best suited to warm climates, but can be designed to tolerate some freezing and periods of low biological activity. Shade from plants and protection from wind mixing is limiting the dissolved oxygen in the water. Constructed wetlands allow for the combination with aquaculture and agriculture (irrigation) what contributes to the optimisation of the local water and nutrient cycle.

Depending on the volume of water, and therefore the size of required land surface, wetlands can be appropriate for small sections of urban areas or more appropriate for peri-urban and rural communities. It is a good treatment technology for communities that already have a primary treatment facility. In this case, the hybrid constructed wetland maybe combined with a solids-free sewer system.

Constructed wetlands are natural systems and do not require electrical energy (unless for pumps), nor chemicals, although the wetland will require some maintenance for the duration of its life. Where land is cheap and available, it is a good option as long as the community is organised enough to thoroughly plan and maintain the wetland for the duration of its life.

Advantages

  • Utilisation of natural processes
  • High reduction of BOD, suspended solids and pathogens
  • Ability to nitrify due to good oxygen transfer
  • Does not have the mosquito problems of the Free-Water Surface or Horizontal Wetland
  • Less clogging than in a Horizontal Subsurface Flow Constructed Wetland
  • Requires less space than a Free-Water Surface or Horizontal Flow Wetland
  • Low operating costs

Disadvantages

  • Requires expert design and construction, particularly, the dosing system
  • Requires more frequent maintenance than a Horizontal Subsurface Flow Constructed Wetland
  • A constant source of electrical energy may be required
  • Long start-up time to work at full capacity
  • Not all parts and materials may be locally available
  • High quality filter material is not always available and expensive
  • Pre-treatment is required to prevent clogging
  • Not very tolerant to cold climates

References Library

BRIX, H.; ARIAS, C. A. (2005): The Use of Vertical Flow Constructed Wetlands for on-Site Treatment of Domestic Wastewater: New Danish Guidelines. In: Ecological Engineering 25, 491-500. Oxford: Elsevier.

CRITES, R.; TCHOBANOGLOUS, G. (1998): Small and Decentralized Wastewater Management Systems. New York: The McGraw-Hill Companies Inc.

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MOREL, A.; DIENER, S. (2006): Greywater Management in Low and Middle-Income Countries, Review of Different Treatment Systems for Households or Neighbourhoods. (= SANDEC Report No. 14/06). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 19.05.2010].

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). URL [Accessed: 28.07.2014].

TILLEY, E.; LUETHI, C.; MOREL, A.; ZURBRUEGG, C.; SCHERTENLEIB, R. (2008): Compendium of Sanitation Systems and Technologies. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (EAWAG) and Water Supply and Sanitation Collaborative Council (WSSCC). URL [Accessed: 15.02.2010].

See document in FRENCH

UN-HABITAT (Editor) (2008): Constructed Wetlands Manual. Kathmandu: UN-HABITAT, Water for Asian Cities Program. URL [Accessed: 15.02.2012].

U.S. EPA (Editor) (1999): Manual – Constructed Wetlands Treatment of Municipal Wastewater. Washington D.C.: United States: Environmental Protection Agency (EPA). URL [Accessed: 24.08.2011].

WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume I. Policy and Regulatory Aspects. Geneva: World Health Organisation. URL [Accessed: 26.02.2010].

WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume II. Wastewater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010].

WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume III. Wastewater and Excreta Use in Aquaculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010].

WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010].

Further Readings Library

Reference icon

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; SCHERTENLEIB, R.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies (Arabic). 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). PDF

This is the Arabic version of the Compendium of Sanitation Systems and Technologies. The Compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.


Reference icon

KADLEC, R. H.; WALLACE, S. D. (2009): Treatment Wetlands. 2nd Edition. Boca Raton: CRC Press, Taylor & Francis Group. URL [Accessed: 18.06.2014].

This book supports in making informed decisions regarding wetland design.


Reference icon

HOFFMANN, H.; PLATZER, C.; WINKER, M.; MUENCH, E. von; GIZ (Editor) (2011): Technology Review of Constructed Wetlands. Subsurface Flow Constructed Wetlands for Greywater and Domestic Wastewater Treatment. Eschborn: Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH. URL [Accessed: 01.07.2013].

This publication intends to help spread awareness and knowledge about the technology of subsurface flow constructed wetlands in developing countries. Constructed wetlands (CWs) can be used as part of decentralised wastewater treatment systems, due to their “robust”, “low-tech” nature with none or few moving parts (pumps) and relatively low operational requirements. CWs can be used for the treatment of domestic and municipal wastewater or greywater, and play an important role in many ecological sanitation (ecosan) concepts.


Reference icon

KUSCHK, P. ; WIESSNER, A.; MUELLER, R.; KAESTNER, M. (2005): Constructed Wetlands – Treating Wastewater with Cenoses of Plants and Microorganisms. Leipzig-Halle: UFZ Centre for Environmental Research. URL [Accessed: 12.10.2011].

The underlying philosophy of phytoremediation research at UFZ (Centre for Environmental Research) is to exploit and to optimise the processes in the rhizosphere. Low-cost, simple systems will be developed to control the environmental problems of different countries in several continents irrespective of their industrial capabilities and conditions – without losing sight of the key principle of cleaning up polluted environmental media in a natural, ecologically balanced way.


Reference icon

MOREL, A.; DIENER, S. (2006): Greywater Management in Low and Middle-Income Countries, Review of Different Treatment Systems for Households or Neighbourhoods. (= SANDEC Report No. 14/06). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 19.05.2010].

This report compiles international experience in greywater management on household and neighbourhood level in low and middle-income countries. The documented systems, which vary significantly in terms of complexity, performance and costs, range from simple systems for single-house applications (e.g. local infiltration or garden irrigation) to rather complex treatment trains for neighbourhoods (e.g. series of vertical and horizontal-flow planted soil filters).


Reference icon

SASSE, L. ; BORDA (Editor) (1998): DEWATS. Decentralised Wastewater Treatment in Developing Countries. Bremen: Bremen Overseas Research and Development Association (BORDA).

Exhaustive report on technological, operational and economic aspects of decentralised waste water treatment systems. Spreadsheet examples support the reader in designing and planning waste water treatment systems components.


Reference icon

STRAUSS, M.; MONTANGERO, A. (2002): FS Management – Review of Practices, Problems and Initiatives. London and Duebendorf: DFID Project R8056, Capacity Building for Effective Decentralised Wastewater Management, Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 24.05.2012].

A study on management and institutional aspects regarding the challenges and possible improvements in managing faecal sludge.


Reference icon

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). URL [Accessed: 28.07.2014].

This compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.


Reference icon

VYMAZAL, J. (2010): Constructed Wetlands for Wastewater Treatment. Prague: Department of Landscape Ecology. URL [Accessed: 17.08.2011].

This document explains how constructed wetlands work and there is a collection of different wetlands all over the world.


Reference icon

WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010].

Volume IV of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater recognizes the reuse potential of wastewater and excreta (including urine) in agriculture and describes the present state of knowledge as regards potential health risks associated with the reuse as well as measures to manage these health risks following a multi-barrier approach.


Reference icon

WSP (Editor) (2008): Technology Options for Urban Sanitation in India. A Guide to Decision-Making. pdf presentation. New Delhi: Water and Sanitation Program (WSP). URL [Accessed: 26.03.2010].

These guidance notes are designed to provide state governments and urban local bodies with additional information on available technologies on sanitation. The notes also aid in making an informed choice and explain the suitability of approaches.


Reference icon

ENPHO (Editor) (n.y.): Decentralised Wastewater Management Using Constructed Wetlands. Kathmandu: Environment and Public Health Organization (ENPHO). URL [Accessed: 17.08.2011].

This paper describes the importance of small-scale decentralised wastewater treatment using reed bed treatment systems (constructed wetlands) in Nepal. It shows how public/community participation can support small-scale construction work while ensuring checks on quality and price of construction, including examples.


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NATURE (Editor); MORGAN, P.; OTTERPOHL, R.; PARAMASIVAN, S.; HARRINGTON, E. (2012): Ecodesign: The Bottom Line. In: Nature: International Weekly Journal of Science 486, 186-189. URL [Accessed: 19.06.2012].

There is no single design solution to sanitation. But there are universal principles for systematically and safely detoxifying human excreta, without contaminating, wasting or even using water. Ecological sanitation design — which is focused on sustainability through reuse and recycling — offers workable solutions that are gaining footholds around the world, as Nature explores on the following pages through the work of Peter Morgan in Zimbabwe, Ralf Otterpohl and his team in Germany, Shunmuga Paramasivan in India, and Ed Harrington and his colleagues in California.


Case Studies Library

Reference icon

ECOSAN CLUB (Editor) (2013): Selected contributions from the 1st WATERBIOTECH conference, 9-11 October 2012, Cairo, Egypt. (= Sustainable Sanitation Pratice, 14). Vienna: Ecosan Club. URL [Accessed: 29.01.2013].

This issue publishes selected contributions from the 1st WATERBIOTECH conference. WATERBIOTECH („Biotechnology for Africa‘s sustainable water supply“) is a coordination and support action funded within the Africa call of the EU 7th Framework Programme.


Reference icon

GJINALI, E.; NIKLAS, J. (2009): Wastewater treatment using constructed wetlands Tirana, Albania - draft. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 06.10.2011].

Within the BMZ (German Federal Ministry for Economic Cooperation and Development) financed project on “Advice on the Decentralisation of the Water and Sewerage Sector in Albania” the GIZ and MPWT (Albanian Ministry of Public Works and Transport) initiated the pilot constructed wetland to raise awareness for low cost, appropriate and decentralised sanitation technologies in line with EU standards. It is aimed to be used as a model treatment plant by the main actors of the sector for training, demonstration, research and replication in peri-urban and rural areas of Albania.


Reference icon

LIPKOW, U.; MUENCH, E. von (2010): Constructed Wetland for a Peri-urban Housing Area Bayawan City, Philippines. (= SuSanA – Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 10.01.2011].

Case study on constructed wetlands for a peri-urban housing area. Septic tanks are used to pre-treat the sewage. The pre-treated wastewater is transported through a small-bore sewer system.


Reference icon

MOHAMED, A. ; KLINGEL, F.; BRACKEN, P.; WERNER, C. (2009): Effluent reuse from constructed wetland system Haran Al-Awamied, Syria. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA) . URL [Accessed: 26.01.2011].

In the village of Haran Al-Awamied a gravity sewer system already existed and waste water was collected for irrigation without any treatment. GTZ and MHC (Syrian Ministry of Housing and Construction) initiated a project for a new ecological treatment plant (settling tank and a vertical flow CW).


Reference icon

OTTER-WASSER (Editor) (2009): Ecological housing estate, Flintenbreite, Luebeck, Germany - draft. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 25.04.2010].

In the Flintenbreite in Luebeck, Germany, blackwater is collected in vacuum toilets. Together with organic wastes from the kitchen it is converted to biogas. Greywater is treated in a reed-bed filter. The project demonstrated the consistent utilisation of ecological building materials, the use of self-sustaining, integrated energy and wastewater concepts, and the implementation of innovative energy saving technologies, with a minimisation of interference in nature, and a responsible, integrative and active cohabitation of the inhabitants.


Reference icon

RAJBHANDARI, K. (n.y.): Sunga Constructed Wetland for Wastewater Management. A Case Study in Community Based Water Resource Management. Shanta Bhawan: WaterAid Nepal. URL [Accessed: 15.08.2011].

The Kathmandu Valley faces critical problems regarding the availability of drinking water, the quality of water and wastewater management. To improve the wastewater management, constructed wetlands, mostly planted with reed, were constructed. The project area is in Madhyapur Thimi municipality, one of Nepal’s oldest settlements.


Reference icon

RAUSCHNING, G.; BERGER, W.; EBELING, B.; SCHOEPE, A. (2009): Ecological Settlement in Allermoehe Hamburg, Germany. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 24.09.2013].

This case study is about a full-scale residential settlement project in an urban area in Hamburg, Germany. The settlement was built between 1982 and 1994 and consists of 36 single-family houses with approx. 140 inhabitants. The project aims at having an ecological closed-loop process via on-site wastewater treatment and therefore independence from a sewage system. Rainwater harvesting, composting toilets and constructed wetlands were the technologies applied in the project. Thereby a high resource and energy efficiency can be achieved.


Reference icon

ROBBINS, D.; STRANDE, L.; DOCZI, J. (2012): Opportunities in Fecal Sludge Management for Cities in Developing Countries: Experiences from the Philippines. North Carolina: RTI International . URL [Accessed: 15.01.2013].

In July 2012, a team from RTI International deployed to the Philippines to evaluate four FSM programs with the goal of reporting on best practices and lessons learned. The four cases—Dumaguete City, San Fernando City, Maynilad Water for the west zone of metro Manila, and Manila Water from the east zone of metro Manila—were chosen to highlight their different approaches to implementing FSM.


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U.S. EPA (Editor) (1993): Constructed Wetlands for Wastewater Treatment and Wildlife Habitat. Washington DC: Environmental Protection Agency (EPA). URL [Accessed: 22.09.2011].

This document provides brief descriptions of 17 wetland treatment systems from that are providing significant water quality benefits while demonstrating additional benefits such as wildlife habitat. The projects described include systems involving both constructed and natural wetlands, habitat creation and restoration, and the improvement of municipal effluent, urban stormwater and river water quality. Each project description was developed by individuals directly involved with or very familiar with the project in a format that could also be used as a stand-alone brochure or handout for project visitors.


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GAUSS, M.; WSP (Editor) (2008): Constructed Wetlands: A Promising Wastewater Treatment system for Small Localities. Experiences from Latin America. Washington D.C.: The World Bank. URL [Accessed: 12.12.2011].

This report provides an overview of how constructed wetlands serve as natural wastewater treatment systems. It focuses especially on the subsurface horizontal flow type—a technology that has high potential for small and medium-size communities because of its simplicity, performance reliability, and low operation and maintenance requirements. The ability of this wetland to reduce pathogens renders the effluent suitable for irrigation of certain crop species if additional health and environmental protection measures are taken. This report describes several experiences with constructed wetland schemes in Central and South America: a full-scale pilot plant in Nicaragua, a community-managed constructed wetland scheme in El Salvador, and other systems in Colombia, Brazil, and Peru.


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JENSSEN, P. (2005): Decentralized Urban Greywater Treatment at Klosterenga Oslo. In: Ecological Engineering-Bridging between Ecology and Civil Engineering, 84-86. URL [Accessed: 21.02.2012].

Today it is possible to foresee completely decentralized wastewater treatment systems in urban areas where the blackwater fractions (urine and faecal matter) is reclaimed for fertilizer and potentially energy production. The water from kitchen sinks and showers (greywater) is treated locally in compact low maintenance systems that constitute attractive landscape elements. These systems can coexist with decentralized water supply.


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MUELLEGGER, E. (Editor); LANGERGRABER, G. (Editor); LECHNER, M. (Editor) (2012): Treatment Wetlands. (= Sustainable Sanitation Practice, 12). Vienna: EcoSan Club. URL [Accessed: 18.07.2012].

Issue 12 of Sustainable Sanitation Practice (SSP) on „Treatment wetlands“ includes 6 contributions: (1.) the Austrian experience with single-stage sand and gravel based vertical flow systems with intermittent loading (the Austrian type is for treating mechanically pre-treated wastewater), (2.) the French experiences with two-stage vertical flow systems treating raw wastewater. (3.) EcoSan Club‘s experiences with TWs in Uganda, (4.) results from multi-stage TW treating raw wastewater in Morocco. (5.) results from horizontal flow experimental systems from Egypt, and (6.) experiences from Denmark and UK on reed beds treating excess sludge from activated sludge plants.


Awareness Raising Material Library

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HORWITZ, P.; FINLAYSON, M.; WEINSTEIN, P. (2012): Healthy Wetlands, Healthy People: A Review of Wetlands and Human Health Interactions. Ramsar Technical Report No. 6. Gland and Geneva: Secretariat of the Ramsar Convention on Wetlands and The World Health Organization (WHO). URL [Accessed: 05.03.2012].

Despite the production of more food and extraction of more water globally, wetlands continue to decline and public health and living standards for many do not improve. Why is this – and what needs to change to improve the situation? If we manage wetlands better, can we improve the health and well-being of people? Indeed, why is this important? This report seeks to address these questions.


Training Material Library

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UNEP (Editor) (n.y.): Waste Stabilization Ponds and Constructed Wetlands Manual. . United Nations Environmental Programme International Environmental Technology Center (UNEP-IETC) and the Danish International Development Agency (Danida). URL [Accessed: 19.04.2010].

Design manual for designers, builders and operators on the design and operation of artificially constructed wetlands and waste stabilization ponds. The supporting information includes a standard systems approach which can be adopted universally; the theoretical background on the biological, chemical and physical processes of each method, the current state of the technology and technical knowledge on how to design, operate and maintain them; and theoretical knowledge on how best the models may be used to describe the systems.


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UN-HABITAT (Editor) (2008): Constructed Wetlands Manual. Kathmandu: UN-HABITAT, Water for Asian Cities Program. URL [Accessed: 15.02.2012].

This manual has been prepared as a general guide to the design, construction, operation and maintenance of constructed wetlands for the treatment of domestic wastewater as well as introduction to the design of constructed wetland for sludge drying.


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U.S. EPA (Editor) (1999): Manual – Constructed Wetlands Treatment of Municipal Wastewater. Washington D.C.: United States: Environmental Protection Agency (EPA). URL [Accessed: 24.08.2011].

This manual discusses the capabilities of constructed wetlands, a functional design approach, and the management requirements to achieve the designed purpose. The manual also attempts to put the proper perspective on the appropriate use, design and performance of constructed wetlands. Furthermore, the document contains two case studies.


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WAFLER, M. (2008): Small-scale Constructed Wetlands for Greywater and Total Domestic Wastewater Treatment. Vienna: seecon international gmbh.

This training material quantifies and characterises grey- and total domestic wastewater production and exemplifies designing of small-scale horizontal and vertical flow constructed wetland system.


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WAFLER, M. (2008): Technical Lecture Greywater Management. Vienna: seecon international gmbh.

This PDFPresentation quantifies and characterises grey- and total domestic wastewater production and exemplifies designing of small-scale horizontal and vertical flow constructed wetland system.