The concept of faecal sludge management makes for an uneasy conversation in most households. People feel uncomfortable with the idea of treated sewage water and often abandon the idea of milking it as an effective water resource, says A. Gurunathan, Director, DHAN Academy.

Sewage makes for an important component of urban infrastructure. What is it about the decentralised natural waste water treatment system (DEWATS) that makes it an unpopular choice despite being an environment-friendly solution?

“It is common to find sewage water being used to grow vegetables in villages. In Madurai, spinach farmers dunk their produce in dirty, untreated water. It is probably about what meets the eye,” says Andrew Jacob, Regional Manager (Tamil Nadu), Consortium for DEWATS Dissemination (CDD) Society.

Mr. Andrews has worked for years, championing the cause of reusing waste water, particularly black water. He says that perception of using ‘unhygienic or impure water’ often creeps into conversation.

It is important to have all households connected to a central treatment system. However, in cities like Madurai, there is poor underground drainage connectivity. Much of the discarded water flows into storm water drains and later into the nearest waterbody, acting as a pollutant, he says.

Having conducted surveys and seminars in Madurai on the subject, Mr. Andrews says that faecal waste management is yet to gain acceptance among the public here.

Explaining its working, Mr. Gurunathan says that it is essential for people to reconsider this innovation.

“Waste water enters a septic tank through which the heavy particles settle down. The sludge enters chambers (partitions within the tank) where anaerobic decomposition takes place. After reactions with micro organisms, methane is released. The water is later routed through a planted gravel filter where rhizobium-rich plants keep nitrogen levels in check through the roots. Water flows into the filter and any addition of film of grease or oil is deposited on the pebbles. Water (under the requisite biological oxygen demand (BOD) and chemical oxygen demand (COD) levels) can be released into a pond or an open well,” he says.

Mr. Andrews says that one needs only an area of 20 square metres to establish such a plant. He adds that though the initial cost of establishment is set at Rs. 70,000, the benefits and maintenance will amount to a pittance.

Only the gravel layer needs to be repacked, he says. The planted gravel filter can be used as an aesthetic element in car parking lots or as a fishing pond, says Mr. Gurunathan.

This water can be used for all activities other than drinking.

According to them, conventional sludge treatment plants may cause foul odour and attract mosquitoes but DEWATS has none of these problems.

“Dhan Academy in Melakkal has installed this treatment plant. A prefabricated unit was established at Karunai Illam in Nilakottai a few years back. The Madurai Corporation can take inspiration and use such effective technology in public spaces,” says Mr. Gurunathan.

In the last eight years, P. Hariharan, a resident of Vaigai Vilas, a gated community in Kochadai, says that he has hardly had to do major maintenance work.

The system, costing Rs. three lakh, has paid off, he claims.

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