Nepal WASH Blog Water, Sanitation and Hygiene (WASH) & Development in Nepal

January 26, 2011

Septic tank with up-flow bio-filter eases life of squatters community in Kathmandu

Filed under: Anita Pradhan's Post,Sanitation,Technology,poverty — Anita Pradhan @ 9:00 am

Till three years ago, life for the squatter community of Narayan Tole with nearly 31 households was dreadful. Situated along the banks of the polluted Samakhusi River, Narayan Tole was one of the most polluted slums of the Capital where the squatters were facing innumerable health and environmental problems. But the squatter’s scenario has changed drastically as the resident of Narayan Tole decided to make their area clean and environment friendly. The polluted river posed health hazards and insecure feeling of potential geographical disaster in the community. There was just one single tap and very few toilets for the entire community. Though elders shared the toilet facilities, children defecated openly and all the waste was discharged directly into the river.

Whoever sees this community today won’t believe that the situation was so bad just three years ago as Narayan Tole has transformed into a clean, eco-friendly squatter community.

The wastewater from toilets are still being discharged into the river but only after it is treated in up flow bio-filter constructed to treat the septic tank effluent. There are two septic tanks in the community with two chambers in each, which are separated by an up flow bio-filter. The filter blocks solid waste in one chamber allowing treated liquid waste into another chamber. The water treated from the filter is then discharged into the river.

Household effluent from the septic tank is treated by the up flow bio-filter. It is a submerged filter with stone media of 6m to 120m deep. Septic tank effluent is introduced to it from the bottom, and the microbial growth is retained on stone media making possible higher loading rates and efficient digestion.

The biochemical oxygen demand (BOD) in the treated water is found to be reduced by 90 percent Mr Kabir Das Rajbhandari, Urban Programme Manager from WaterAid says. When BOD levels are high, dissolved oxygen levels decrease because bacteria consume oxygen that is available in the water. Since less dissolved oxygen is available in the water, it’s difficult for fish and other aquatic organisms to survive.

This technology is highly efficient in areas where available space is limited. Unlike Reed Beds, which require 1m2/person, the septic tank with upflow bio-filter can be constructed in a densely settled urban area. Because the design in fairly low maintenance, it can be managed by the community. Such treatment plants can be installed in individual homes too as they are affordable and occupies only a little space,” Mr Rajbhandari further adds.

The drastic change has come because of the people’s willingness to change. This whole transformation is an attempt of residents from squatter community to urge people to keep environment clean and show others that squatters are not polluters of rivers. The effort of this small squatter community can be a good example for everyone working for the management of urban water and sanitation. Even other slums could learn from them so that they could at least live a healthy and environment-friendly life. The Narayan Tole residents have felt the difference due to the presence of this treatment plant. They feel much relieved now since the foul smell has reduced to a great extent.. With toilets in almost all the homes in this settlement, people no longer defecate in the open.

The water and sanitation project implemented by LUMANTI in nearby squatter community of Kahadipakha inspired them to improve their community’s condition too. Community members approached LUMANTI to help in the community. With financial and technical support from WaterAid and UN-HABITAT, LUMANTI helped to improve the situation of the settlement.

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Written by Anita Pradhan, Documentation Manager, WaterAid in Nepal.

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