A colony of agricultural scientists in central Delhi has shown that it is viable to decontaminate water while mimicking nature, and that the mechanism can be highly gainful. The Indian Agricultural Research Institute has successfully installed a purification system for their homes in Pusa that can clean 2.2 million litres of domestic sewage daily using almost zero thermal power.
The water, devoid of harmful chemicals, can be used for gardening or irrigation. The treated water can help generate good produce from 120 hectares of farmland – about 100 football fields – assuring sustained income.
IARI director Dr HS Gupta said the produce has been found to be fit for human consumption. “All harmful chemicals in the sewage are absorbed by the wetland plants that are part of the purification system,” he added.
The system, costing Rs. 1.2 crore, is based on nature’s ways. The dirty water is collected and flown through an array of wetland plants with capacity to absorb chemicals such as lead and mercury up to 1,000 parts per million (ppm).
Apart from assured agricultural income, the wetland plants can be harvested for a revenue of `18 lakh annually.
The biomass – organic matter derived from the plants – can be used to develop 9,000 sq m of chipboard (a kind of building material), or can be sold in open market at Rs. 2,000 per tonne. About 36 lakh tonnes of biomass is produced in the facility annually, said project director Ravinder Kaur.
While the process of cleaning is slow and labour intensive, the system consumes only 1% of the power required to run a conventional sewage treatment plant.