Chennai’s produce wholesale market Koyambedu generates over 200 tonnes of garbage a day, of which 12-15 tonnes are used by a biomethanation plant to generate electricity, which is uploaded to TNEB every day. Now, as the market grows and handles more produce, more waste is being generated. In a smart move, the Chennai Metropolitan Development Authority (CMDA), the Market Management Committee, and the Tamil Nadu Pollution Control Board have roped in CSIR-Central Leather Research Institute to upgrade the plant.
Says C. Prem Ananth Surendran, Deputy Planner, CMDA, “Koyambedu accounts for 10 per cent of the city’s solid waste. At present, 10 tonnes of segregated organic waste from the wholesale market are used to generate 1,300 units of electricity, which is exported to TNEB each day. In order to use the mounting amounts of waste, the plant needs an upgrade.”
The plant is designed to handle only vegetable waste, but the upgrade will add a digester, which means it will be able to use waste from slaughterhouses and restaurants in the neighbourhood as well as treat sewage and banana stems to generate biogas. The upgrade is expected to be complete by 2016, and will cost over Rs. 10 lakh. It will provide 2,000 households in the vicinity with biogas. It could also continue providing electricity to the grid, if it proves feasible
Set up in 2006, the plant has been supplying electricity to the grid but not continuously, with commercial hiccups stalling it. In 2010, Ramky Enviro Engineers equipped it with a German engine and later upgraded this with a Czech one in 2014. Finally, the CMDA has come up with this new plan. The upgrade has many benefits, says Surendran. “It will result in the lessening of carbon dioxide emissions and greenhouse gas effects and it will prevent groundwater contamination and air pollution.”
Dr. P. Shanmugam, principal scientist, CSIR-CLRI, is exploring the potential of pulped banana stems to create biogas. He says it is energy efficient to convert waste into biogas rather than electricity. “When waste is used to produce electricity, 65 per cent of gas is wasted. Whereas, biogas generation utilises 100 per cent of the gas generated. Since it is used for cooking, it requires no purification, resulting in reduced costs.” The upgrade will prepare and add seed sludge into the digester, improving the pre-fermentation hydrolysis process and exploring the various uses of biogas for domestic use.
The government is working towards setting up 39 such biogas plants in the state. The plant at Arcot, Vellore, utilises domestic solid waste to generate electricity to light up street lamps.
Durganand Balsavar, city-based architect and urban planner, says the project at Koyambedu is feasible in principle. “It is essential that we recycle to create sustainable cities. Adequate training for personnel to run and maintain the plant efficiently is required. If the process can be scaled up to neighbourhoods in the suburbs, it will become more affordable,” he says. Although challenges exist in the form of high infrastructure and periodic maintenance costs, over time, better models can be evolved. “One can expect teething troubles while handling waste of such proportions. But in the long run, we can expect to see a transformed city,” adds Balsavar.
