CHENNAI: After years of struggle by local residents, Tambaram Municipality has finally planned to clear the Kannadapalayam dumpyard using the biomining method. The civic body has switched to the new technology, which officials believe is much more efficient and the land would almost return to it original form.
Besides, the municipality has started implementing ‘Wednesday scheme’ to segregate degradable and non-degradable wastes at the source itself.The move has come after the National Green Tribunal pulled up the civic body over environmental hazards caused by the dumpyard and ordered its removal. “We initially planned to convert it (the garbage hill) into a small garden. But we have changed the plans opting for biomining,” says Albert Arulraj, sanitary inspector in charge of the dumpyard.
The process
“Biomining process is a popular solution for huge landfills,” says Nagesh Prabhu, director of Zigma Global Environ. While explaining the process, he adds that “it is a near zero emission process where the dump-hills can be cleared as if they never existed.”
He said a set of machinery would be set up near the garbage hill to segregate the combustible and non-combustible materials with an automatic machine. He shattered the myth that the dump will be cleared soon after the machinery is set up.
This is mainly on account of the fact that dumpyards are complex. They contain methane, and other harmful gases since they have been there for many years. There is also water pollution caused by ‘leachate’ which is produced from garbage decay. “If you let a earthmover to climb over the garbage hill and simply open it, there is a chance that these gases might escape in a rush. Sometimes it might cause fire accidents and there is a probability that those working in the dumpyard will feel nauseous,” he warns. Hence, the process starts with pre-stabilisation where bio-culture is sprayed. Bio-culture is basically bacteria which will rapidly degrade the material that is not fully bio-degraded. It will stabilise the dump, which includes sanitising it, freeing it from pathogens and making it free of ammonia, methane, hydrogen sulphide and other obnoxious gases.
Waste is segregated by a machine and combustible materials like plastic and wood sent to cement factories to be used as alternate fuel. But one might ask, “Will the burning plastic not produce air pollution?”According to norms, the smoke emitted by burning a material in the cement furnace at 90 degree C as alternate fuel will be sent through a scrubber (an air filter), which will absorb all the poisonous substance of the gases. The non-combustible materials like sand, soil and other degraded food waste will be dumped again in the given land as they can easily decay and maintain the carbon content.
“There is carbon content in the soil, which we receive through food and we give it back through wastes,” said the director of one of the companies involved in bio-mining. “This routine is damaged once you start to incinerate the garbage. The carbon content is depleted too much and also produces air pollution. But by bio-mining, the required carbon is given back to the earth. Though the process is simple, it’s highly scientific.”The sanitary inspector said the 1.5 lakh tonne garbage heap in 2.3 acre land will be cleared within a year. The tender has been issued and they are waiting to finalise the contractor, after which garbage will be removed.
