CHENNAI: The Chennai Metro Water Supply and Sewerage Board (CMWSSB) will appoint a consultant to prepare a Detailed Feasibility Report (DFR) to explore the generation of Bio-CNG from sludge collected at 13 sewage treatment plants across four locations within the city limits.
The move, approved at a recent Board meeting, is aimed at assessing the technical and commercial viability of converting sewage sludge into Bio-CNG and identifying avenues for revenue augmentation. The project is proposed to be taken up under the public-private partnership model.
According to the Board’s Managing Director, TG Vinay, the consultant will study the scope for producing Bio-CNG from sludge generated at sewage treatment plants and examine options for marketing the fuel, either through cylinders or pipeline networks. The agency will also inspect all the treatment facilities and submit recommendations on implementation models.
The 13 sewage treatment plants are located at Kodungaiyur, Koyambedu, Nesapakkam and Perungudi. Metro Water officials said the utility already generates electricity using biogas derived from sewage sludge at the Kodungaiyur plant. Sewage collected at pumping stations is conveyed to treatment plants through pipelines, where plastic and other waste are removed during preliminary screening.
The sludge that settles during the clarification process is transferred to digesters and stored in airtight conditions for about seven days, enabling the production of methane-rich biogas. The extracted gas is currently used to run engines for power generation at the Kodungaiyur facility.
Another senior official said administrative sanction has been accorded for appointing a consultant, and tenders will be floated shortly. The feasibility report is expected to guide the Board on scaling up energy recovery from sludge and monetising Bio-CNG as an alternative, cleaner fuel.