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Initial Situation

The Philippines is a country o more than 7,000 islandswith generally sucient resh water resources. But within thelast years these resources are increasingly threatened, mainlydue to pollution.

The resh water supply is provided through groundwater,

rivers and lakes. On small islands the resh water supply islimited to resh water lenses under the islands and throughrainwater. Improved water supply, rapid population growthand expanding economic development have led to anenormous raise o resh water consumption. In some regionso the country, even non-replenishable water resources havealready been exploited and exhausted.

The situation is getting worse through extensive waterpollution. In general, more than 90 % o sewage is notdisposed o correctly or treated in an environmentally soundmanner. Most o the existing wastewater treatment acilitiesare inadequate, and more than 25 % o the populationhas no access to any sanitation services. This is also the

main source o waterborne diseases, like diarrhea, helminthinections and dermatitis (skin infammation).On the other hand, the necessary legislative basis

already exists. The Clean Water Act obliges the communitiesto undertake sewage collection and treatment to protectwater resources. But most municipalities do not have sucientunds or the construction as well as or the operation andmaintenance o conventional centralized treatment systems.They need aordable alternatives, to cope with the challengeto provide environmentally riendly, nancially viable andsustainable wastewater treatment acilities.

Decentralized treatment acilities and on-site sanitationsystems are such alternative concepts.

Appropriate Solution Alternative: Constructed Wetland

Constructed wetlands are one option or sustainablewastewater treatment. They use natural processes or cleaningthe wastewater. This technology has been eectively appliedin Western countries or decades and in recent years also inSoutheast Asia.

Constructed wetlands are man-made, engineeredsystems that remove organic pollutants and nutrients rom

wastewater through ltering it by soil and plants with thehelp o microorganisms. In general, constructed wetlandscan be divided into 3 dierent types: Free Water Surace(FWS), Horizontal Sub-surace Flow (HSSF) and VerticalSub-surace Flow (VSSF). The latter two types have the

advantage that the wastewater fows beneath the ltersurace, thus the risk o pathogen exposure and mosquitobreeding is minimized. This product sheet will ocus on thetwo sub-surace fow types.

Sub-surace fow systems are composed o a basin thatis sealed with impermeable material such as clay, plasticliner or concrete. It is lled with lter media (soil, sand orgravel) and covered with plants. A eeder system, drainagepipes and an outlet or the waste water are essential parts othe system. As plant material reeds, cattails and rushes canbe used, preerable local species (or example Tambo, alsocalled Phragmites).

The cleaned wastewater can be re-used, e.g. or

irrigation or toilet fushing. This will reduce the demandor resh water and thereore the exploitation o the waterresources.

Advantages

Constructed wetlands are a nature-close environmentallyriendly treatment method. In sub-surace fow systems therewill be no problems with smell or mosquito breeding becausethere is no open water table. In addition, a constructedwetland can be nicely integrated into the landscape.

Construction costs can be reduced through using locallyavailable materials. Costs or operation and maintenance

are extremely low and aect mainly pumping (i waste watertransport cannot be done by gravity). The daily operationand maintenance procedures require only simple technicalskills and the necessary knowledge can be easily obtainedthrough training.

Application is recommended especially or rural andsuburban areas. In urban areas the space needed mightbe a limiting actor (design parameter: m2 per person as anaverage in tropical countries).

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Example City of Bayawan, Negros Oriental:The first constructed wetland in the Philippines for domestic waste water

The City o Bayawan is located in the southwest o theProvince o Negros Oriental (Visayas) and is composed o28 barangays. It has a total land area o approx. 70,000hectares, more o 80 % are dened as rural.

Due to the construction o a new coastal road, an inormalsettlement o sher amilies in barangay Villareal had to berelocated. Together with the NGO Gawad Kalinga the citystarted a social housing project. On an area o 7,4 hectares704 housing units and social inrastructure (health center,multi-purpose hall etc.) are being built or the shermen andtheir amilies. Following the provisions o the Clean WaterAct and the cities objectives, the project should be in line

with environmental protection and conservation. Thereore itwas decided to construct a wastewater treatment acility orthe new village.

The LGU built a treatment system with clustered three-chamber septic tanks and a two-cell constructed wetland. Thewetland is composed o a vertical fow and a horizontal fowsoil lter, planted with the local variety o Tambo (Phragmites

karca). The treated water is re-used or construction, irrigationand reghting.

The treatment acility covers an area o approx. 3,000square meters. The estimated costs are about 10,000,000PhP (higher than average costs or such a acility due to thetopographic conditions). The wetland is nanced by the cityadministration through a loan.

The GTZ Water and Sanitation Program supportedthe project with technical assistance in planning, design,construction monitoring, social preparation and trainings.

The Bayawan Constructed Wetland is the rst systemo this kind or the treatment o municipal sewage in thePhilippines. The city plans two more acilities or the public

market and the new bus terminal.

More information:

If-Sh Fql Askd QsisConstructed Wetlands: A sustainable option for

waswa am i h Philippis (availabl www.wasaslid.g.ph)

Philippi Saiai Sbk ad DisiAid (availabl www.wasaslid.g.ph)

MAyor GerMAn P. SArAA, Jr.City o Bayawan, Negros Oriental

Tel.: +63 (035) 531 0020 to 21

Web: www.bayawancity.gov.ph

For more information, please contact:

enGr. HAnnS-BernD KucHtADILG-GTZ Water and Sanitation Program5th Floor, Francisco Gold Condominium II,EDSA corner Mapagmahal Street, Q.C.

Tel.: +63 2 927 1875; +63 2 927 1884

Email: gtzwater@info.com.ph

Web: www.watsansolid.org.ph ; www.gtz.de