BIN THERE, DONE THAT

Waste disposal is the bane of many a new-age city, and bustling metros such as Chennai, Delhi, Mumbai and Bangalore are no exception.

The problem does not entirely lie with garbage collection agencies, who are doing their best to lift all the refuse. Rather, the thousands of tonnes of solid and liquid waste generated every day by the gargantuan population of these thriving Indian cities pose the conundrum with respect to waste disposal: where will it all go?

One proposed solution has been incineration of the waste to make it more compact and manageable. Burning of waste can reduce the volume by up to 90 per cent. Energy can also be generated as a useful by-product of the process.

But plans to set up such waste-to-energy units in India have met with staunch resistance from environmentalists. Older plants that were set up in Delhi, Hyderabad, Vijayawada and Lucknow were shut down for reasons ranging from low calorific value of waste to lack of financial viability.

learnings

Experts from Singapore, however, assure that modern technology can mitigate the pollution caused by incineration of waste. Singapore has four waste-to-energy plants in operation around the clock, handling some 7,600 tonnes of garbage thrown away by its 5-million-strong population every day. The ash left after the burning process is transported by boat to Semakau Island, a man-made landfill site in the middle of the ocean. During a site visit to the largest of these plants, dubbed the Tuas South Incineration Plant, General Manager Chong Kuek On, emphasised that carbon monoxide emissions from the plant are less than a thirtieth of the permissible limits. Particulate substances content is just one-hundredth of Singapore’s safety limits, which are in line with best practices around the world.

Built in 2000 at a cost of $890 million, the plant can handle 3,000 tonnes of waste every day to generate 80 MW of electricity. Chong highlighted the absence of smoke from the chimney stack of the utility to drive home his point about clean emissions.

The process

The plant is highly automated and Chong underlines his requirement of 11 crew members at all times to ensure that the plant is running smoothly. Giant claws heave piles of rubbish brought by trucks into the incineration chambers, where it is burnt. Subsequently, the ash is carted by conveyor belt to another area for loading on to ships for transport to the landfill site. Meanwhile, waste gases from the process are funnelled through a purification system that neutralises the harmful chemicals and filters out particulate content. The chamber is pressurised in order to keep vapours from escaping. In addition, metal content within the waste is sorted out from the debris and sold as scrap to steel mills and other users.

Chong of the Tuas South Incineration Plant says that India could make use of the waste-to-energy technology harnessed by his country in order to come to terms with its own garbage disposal problems. The opposition to the process is unjustified, according to Chong, who says the technology has helped Singapore keep clean. Convincing the opponents, therefore, will hinge on scientific data that verifies the benefits of waste-to-energy technology.

arvind.jayaram@thehindu.co.in

(This article was published on November 26, 2013)
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