Sewage treatment plants run by Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) will now have new facilities to tap electricity from waste water.
It is learnt that the city’s water manager had decided to set up new sewage-to-electricity facilities at the sewage treatment plants (STP) in Nesappakkam, Perungudi and two plants in Kodungaiyur. The selected treatment plants have a combined sewage treating capacity of 350 MLD (Million Litres per Day). Explaining the technical details, Sivashanmugam said that the residues, which are mostly organic matter, stored at the bottom, would be sent into air-tight container-like structures letting the certain bacteria to act on the organic matter in an anaerobic state to produce methane (biogas). Biogas would heat up the machines to generate electricity.
“Earlier, we had been decomposing organic matter left behind using oxygen-consuming-bacteria. This system costs much more as we have to supply more oxygen. The bacteria will consume oxygen and release carbon dioxide, which is of no use,” he added.
The CMWSSB would utilise the electricity to run the sewage treatment plants and envisage tapping 80 per cent of the electricity needed to run the plants. “Even though we have facilities to generate power from biogas at the sewage treatment plants, tenders were floated to install new upgraded equipment,” another official said.
Meanwhile, Metrowater has initiated steps to upgrade and maintain the sewage treatment plants in Nesappakkam, Perungudi, Koyambedu and Kodungaiyur. “We are also planning to let the treated water into lakes in order to recharge groundwater instead of letting it flow into the sea,” the official added.
- Certain type of bacteria acts on organic matter in anaerobic condition to produce biogas
- Biogas will be used to heat machines and generate power
- 80 per cent of the power needed to run STPs will be generated from sewage
- CMWSSB has STPs at Perungudi, Nesapakkam, Kodungaiyur and Koyambedu with a combined capacity of 727 MLD