Free-Water Surface CW

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

Executive Summary

A free-water surface constructed wetland (also called free water surface, FWS) is a series of flooded planted channels or basins. It aims to replicate the naturally occurring processes of a natural wetland, marsh or swamp. As water slowly flows through the wetland, particles settle, pathogens are destroyed, and organisms and plants utilize the nutrients. This type of constructed wetland is commonly used as an advanced treatment after secondary or tertiary treatment processes. Pre-treating of wastewater in e.g. a septic tank or biogas settler is necessary to avoid excess accumulation of solids and garbage. Because of the open water surface, there is a risk of mosquito breeding if not properly designed. Plants grown on the wetland may be used for composting or energy production and the effluent can be used for aquaculture and irrigation. This system is appropriate for small sections of urban areas (e.g. decentralised treatment for a community or several housings or small industries) or even more appropriate for peri-urban and rural communities because of the land surface required.

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 biodegradable 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). 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. Unlike the Horizontal Subsurface Flow Constructed Wetland, the free-water surface constructed wetland allows water to flow above ground exposed to the atmosphere and to direct sunlight. As the water slowly flows through the wetland, simultaneous physical, chemical and biological processes filter solids, degrade organics and remove nutrients from the wastewater.

Raw blackwater should be pre-treated to prevent the excess accumulation of solids and garbage. Once in the pond, the heavier sediment particles settle out, and this also removes the nutrients attached to them. Plants and the communities of microorganisms that they support (on the stems and roots), take up nutrients like nitrogen and phosphorus. Chemical reactions may cause other elements to precipitate out of the wastewater. Pathogens are removed from the water by natural decay, predation from higher organisms, sedimentation and UV irradiation.

Although the soil layer below the water is anaerobic, the plant roots exude (release) oxygen into the area immediately surrounding the root hairs, thus, creating an environment for complex biological and chemical activity.

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, they are suited to be combined with aquaculture or sustainable agriculture (irrigation).

Design Considerations

In a free-surface constructed wetland (also known as surface flow CW or free water surface CW), water flows above ground and plants are rooted in the sediment layer at the base of the basin or floating in the water. As the water slowly flows through the wetland, simultaneous physical, chemical and biological processes filter solids, degrade organics and remove nutrients from the wastewater. The channel or basin is lined with an impermeable barrier (clay or geo-textile) covered with rocks, gravel and soil and planted with native vegetation (e.g., cattails, reeds and/or rushes). The wetland is flooded with wastewater to a depth of 10 to 45 cm above ground level. The wetland is compartmentalized into at least two independent flow paths. The number of compartments in series depends on the treatment target. The efficiency of the free-water surface constructed wetland also depends on how well the water is distributed at the inlet. Wastewater can be fed into the wetland, using weirs or by drilling holes in a distribution pipe, to allow it to enter at evenly spaced intervals.

The basin is planted advantageously with native plants. Compared to subsurface wetlands (horizontal flow or vertical flow), free-surface CW’s can be vegetated with emergent, submerged and floating plants (SA’AT 2006; TILLEY et al. 2008).

 TILLEY et al 2014 Schematic of the Free Water Surface Constructed Wetland

Functional schematic of a free-water surface constructed wetland. Source: TILLEY et al. (2008) 

To avoid clogging and the excess accumulation of solids and garbage, pre-treatment is necessary. Pre-treatment of wastewater 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, biogas settler, anaerobic baffled reactor, imhoff tank, UASB reactor, or compost filter (HOFFMANN et al. 2010).

Pre-treated wastewater enters the basin via a weir or a distribution pipe. It is important for the treatment effect that it is distributed over the whole width. Once in the pond, the wastewater flows slowly through the basin and the heavier sediment particles settle, also removing nutrients that are attached to particles. Plants, and the communities of microorganisms that they support (on the stems and roots), take up nutrients like nitrogen and phosphorus. Chemical reactions may cause other elements to precipitate out of the wastewater. Pathogens are removed from the water by natural decay, predation from higher organisms, sedimentation and UV irradiation. Although the soil layer below the water is anaerobic, the plant roots release oxygen into the area immediately surrounding the root hairs, thus creating an environment for complex biological and chemical activity (TILLEY et al. 2008).

            Plants for free-surface flow constructed wetlands. Source SA’AT (2006)

Plants for free-water surface flow constructed wetlands. Source SA’AT (2006)            

Free-surface CW’s normally require more surface than a subsurface system (e.g. a horizontal flow or vertical flow wetland). This is because the porous subsurface filter medium in subsurface systems provides a greater contact area for treatment activities. Consequently, compared to a subsurface filter, free-surface wetlands are designed bigger for the same volume of wastewater (SA’AT 2006).   


Health Aspects/Acceptance

The open surface can act as a potential breeding ground for mosquitoes. However, good design and maintenance can prevent this (e.g. proper pre-treatment, read more about it in WALTON 2003).

Free-water surface constructed wetlands are generally aesthetically pleasing, especially when they are integrated into pre-existing natural areas. Thus, they can provide wildlife habitat beside the treatment process.

Care should be taken to prevent people from coming in contact with the effluent because of the potential for disease transmission (TILLEY et al. 2008; SA’AT 2006) and the risk of drowning in deep water.

The biggest health risk arises from settled wastewater in the pre-treatment facility 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 safe 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 also means 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-water surface and waste stabilisation ponds have lower capital costs than horizontal subsurface-flow constructed wetlands (horizontal and vertical). Surface-flow constructed wetlands have also often lower maintenance and repair costs than in subsurface systems. On the other hand, if land area is not available or ground prices high, the large surface can be a big disadvantage (SA’AT 2006)

Operation and 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).

Regular maintenance should ensure that water is not short-circuiting, or backing up because of fallen branches, garbage, or beaver dams blocking the wetland outlet. Vegetation may have to be periodically cut back or thinned out. In general free-surface CW’s are easier to regulate then subsurface systems. On the other hand they have not a great cold temperature tolerance and odour and mosquito problems can occur if operated and maintained incorrectly. A number of systems have had problems with clogging and unintended surface flows (SA’AT 2006).

An important part of O&M is to empty the sludge of the pre-treatment facilities (e.g. septic tank). This should be done in a proper and safe way (see human-powered emptying and transport and motorised emptying and transport). The filter bed of the constructed wetland may also be changed sometimes. The old material, full of earth and organic matter may be directly used as soil amendment or composted first, similar to a planted drying bed.

At a Glance

Working Principle

Pre-treated wastewater enters the basin via a weir or a distribution pipe. Once in the pond, the heavier sediment particles settle out, also removing nutrients that are attached to particles. Plants, and the communities of microorganisms that they support (on the stems and roots), take up nutrients like nitrogen and phosphorus (TILLEY et al. 2008).

Capacity/Adequacy

Depending on the volume of water, and therefore the size, wetlands can be appropriate for small sections of urban areas or more appropriate for peri-urban and rural communities phosphorus (TILLEY et al. 2008).

Performance

Free-water surface flow CW’s can achieve high removals of suspended solids and moderate removal of pathogens, nutrients and other pollutants such as heavy metals phosphorus (TILLEY et al. 2008).

Costs

High land costs than other CW systems (big surface required), cheap O&M costs

Self-help Compatibility

O&M by trained but not highly skilled labours, most of construction material locally available. Construction needs expert design.

O&M

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

Reliability

If wastewater is correctly pre-treated it is a very reliable technology.

Main strength

No electricity required, can be built with local materials

Main weakness

High permanent space required, as well as extensive construction. It can give rise to mosquito breeding and odour problems.

Applicability

Free-water surface constructed wetlands can achieve a high removal of suspended solids and moderate removal of pathogens, nutrients and other pollutants, such as heavy metals. This technology is able to tolerate variable water levels and nutrient loads. Plants limit the dissolved oxygen in the water from their shade and their buffering of the wind; therefore, this type of wetland is only appropriate for low-strength wastewater. This also makes it appropriate only when it follows some type of primary treatment to lower the BOD. Primary treatments, such septic tanks, anaerobic baffled reactors, imhoff tanks, biogas settlers, UASB reactors, or compost filter are the most suited lower the BOD and prevent clogging of the constructed wetland. Because of the potential for human exposure to pathogens, this technology is rarely used as secondary treatment. Typically, it is used for polishing effluent that has been through secondary treatment, or for stormwater retention and treatment.

The free-water surface wetland is a good option where land is cheap and available. Depending on the volume of the water and the corresponding area requirement of the wetland, it can be appropriate for small sections of urban areas, as well as 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.

This technology is best suited for 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 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.

Constructed wetlands allow for the combination with aquaculture and agriculture (irrigation) what contributes to the optimisation of the local water and nutrient cycle.

Advantages

  • Aesthetically pleasing and provides animal habitat
  • High reduction of BOD and solids; moderate pathogen removal
  • Can be built and repaired with locally available materials
  • No electrical energy is required
  • No real problems with odours if designed and maintained correctly
  • No chemical required, process stability
  • Low operating costs
  • Can be combined with aquaculture and agriculture

Disadvantages

  • May facilitate mosquito breeding
  • Requires a large land area
  • Long start-up time to work at full capacity
  • Requires expert design and construction
  • Requires supervision
  • Not very tolerant to cold climates

References Library

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

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]. PDF

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]. PDF

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

MERZ, S. L. (2000): Guidelines for Using Free Water Surface Constructed Wetlands to Treat Municipal Sewage. Brisbane: Queensland. Department of Natural Resources.

POH-ENG, L.; POLPRASERT, C. (1998): Constructed Wetlands for Wastewater Treatment and Resource Recovery. Bangkok: Environmental Sanitation Information Center (ENSIC), Asican Institute of Technology (AIT).

POLPRASERT, C.; VEENSTRA, S. ; VAN DER STEEN, P. (2001): Wastewater Treatment II. Natural Systems for Wastewater Management. Delft: United Nations Educational, Scientific and Cultural Organization Institute for Water Education (UNESCO-IHE).

SA’AT (2006): Subsurface Flow and Free Water Surface Flow Constructed Wetland with Magnetic Field for Leachate Treatment. Johor Bahru: University Teknologi Malaysia. URL [Accessed: 23.08.2011]. PDF

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]. PDF

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. URL [Accessed: 15.02.2010]. PDF

See document in FRENCH

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]. PDF

VYMAZAL, J.; SENGUPTA, M. (Editor); DALWANI, R. (Editor) (2008): Constructed Wetlands for Wastewater Treatment: A Review. (= Proceedings of Taal 2007: The 12th World Lake Conference). Czech Republic: ENKI, o.p.s. and Institute of Systems Biology and Ecology, Czech Academy of Sciences. URL [Accessed: 18.06.2014]. PDF

WALTON, W.E. (Editor) (2003): Managing Mosquitoes in Surface-Flow Constructed Treatment Wetlands. Riverside: University of California. URL [Accessed: 12.10.2011]. PDF

Further Readings Library

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]. PDF

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]. PDF

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]. PDF

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

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

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.


Reference icon

SA’AT (2006): Subsurface Flow and Free Water Surface Flow Constructed Wetland with Magnetic Field for Leachate Treatment. Johor Bahru: University Teknologi Malaysia. URL [Accessed: 23.08.2011]. PDF

This study conducted using two-stage lab-scale Subsurface Flow (SSF) and Free Water Surface (FWS) constructed wetland under influence of magnetic field to treating the leachate. Furthermore it includes a general description about the constructed wetland systems free water surface flow and subsurface flow.


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]. PDF

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

U. S. EPA (Editor) (1998): Design Manual – Constructed Wetlands and Aquatic Plant Systems for Municipal Water Treatment. Washington D.C.: United States : Environmental Protection Agency (EPA). URL [Accessed: 24.08.2011]. PDF

This document is a very complete design manual about constructed wetlands and aquatic plant systems for municipal water treatment. It describes different designs, application, performance and it includes several case studies.


Reference icon

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]. PDF

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.


Reference icon

WALTON, W.E. (Editor) (2003): Managing Mosquitoes in Surface-Flow Constructed Treatment Wetlands. Riverside: University of California. URL [Accessed: 12.10.2011]. PDF

This publication discusses how the design and operation of surface-flow wetlands constructed primarily for water quality improvement can contribute to issues related to high populations of mosquitoes.


Reference icon

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

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]. PDF

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.


Reference icon

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]. PDF

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.


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]. PDF

This book supports in making informed decisions regarding wetland design.


Reference icon

VYMAZAL, J.; SENGUPTA, M. (Editor); DALWANI, R. (Editor) (2008): Constructed Wetlands for Wastewater Treatment: A Review. (= Proceedings of Taal 2007: The 12th World Lake Conference). Czech Republic: ENKI, o.p.s. and Institute of Systems Biology and Ecology, Czech Academy of Sciences. URL [Accessed: 18.06.2014]. PDF

Presentation of different types of constructed wetlands for various types of wastewater.


Case Studies Library

Reference icon

BOJCEVSKA, H. (n.y.): Treatment performance of a free water surface constructed wetland system receiving sugar factory effluents in the Lake Victoria region. Linkoeping: University of Linkoeping. URL [Accessed: 24.08.2011]. PDF

The aim of the project was to investigate strategies for improving the wastewater treatment of the factory with constructed wetlands. As part of that project, eight pilot scale free-water surface wetlands were constructed to facilitate experiments with such systems. Those pilot scale wetlands will be used in the proposed study.


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]. PDF

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

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]. PDF

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.


Reference icon

GREENWAY, M. (n.y.): The role of constructed wetlands in secondary effluent treatment and water reuse in subtropical and arid Australia. Nathan: Griffith University. URL [Accessed: 24.08.2011]. PDF

This paper addresses the role of constructed wetlands in nutrient and pathogen removal in Queensland’s, wetlands, and presents three case studies with respect to effluent reuse.


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]. PDF

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.


Reference icon

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

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.


Awareness Raising Material Library

Reference icon

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]. PDF

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.