Tarun Nanda : 'It's not easy solving this problem, not only does the solution have to be cheap, it has to be easy to maintain by the residents themselves and it has to put up with the various abuses that the people can throw at it, from theft to vandalism to dumping of garbage. As well as not using any electricity, the actual structure cannot be made from steel, concrete or bricks as it is in a protected forest area.
To achieve this it is necessary push the boundaries of what is possible and what has been done before in terms of using sustainable materials and in wastewater treatment,
- The walls are going to be living structures, formed from coconut fibre, soil and specially selected plants whose roots will grow down deep to provide the strength and soil stability needed. The walls will also act like drains, filtering rainwater before it enters the pond.
- Bamboo will be used to form an initial structure while the plants take root, the bamboo will eventually rot away leaving behind the living walls.
- Hydraulic jumps are a phenomenon where water levels 'jump' creating highly turbulent regions that entrain large amounts of air. You can see the effect for yourself if you let your tap run in the sink and observe the circular ridge that forms. They provide a way of aerating water without using pumps, they are commonly used at a large scale but have not been incorporated into open sewers until now.
- The constructed wetland will build on the experience gained on the farmhouse in Delhi in using earthworms on a much larger scale and growing plants that can provide craft material.
- For the first time edible plants will be used in a constructed wetland with a view to consuming the produce once the proper tests have been carried out.
- Open sewers will also be adapted to provide some level of treatment as the wastewater flows through the settlement, decreasing the size of the central treatment facility necessary.'