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ENVIRONMENT-INDIA: Wealth From Waste With Bio-Digesters

Hari Krishnan* - IPS/IFEJ

THIRUVANANTHAPURAM, Kerala, Jun 18 2007 (IPS) - Saji Das foresees a time when people in this state, at the southern tip of the Indian peninsula, will compete to get at food waste and other rotting organic rubbish rather than holding their noses and walking away quickly.

Biodigester outside Thiruvananthapuram. Credit: Hari Kumar

Biodigester outside Thiruvananthapuram. Credit: Hari Kumar

Das, who has developed special organic digesters capable of dealing with a variety of garbage, has become a pioneer of sorts in this state which boasts of human development indices that compare with the developed world, but has some way to go when it comes to scientifically managing garbage.

So efficient and clean are the digesters that Biotech, a non-governmental organisation (NGO) that he runs, has been named a finalist for the 2007 Ashden Awards in Britain, sometimes called the ‘Green Oscar’ for the prestige it carries.

It all started in 1994 when Das, tired of seeing mountains of stinking food waste lying about unattended in public places and crawling with flies, rats and other disease-breeding vermin, decided to do something about it. His strategy was simple; find cheap, environment-friendly ways to convert what seemed like an endless supply of rich organic matter into valuable methane (cooking gas) and fertiliser.

Once Das had perfected a digester that worked well on food waste, all he had to do was nose around for the smelliest and biggest dumps in the state’s urban areas. He struck gold in the town of Kadakkal in Kollam district where now an integrated recycling plant digests one tonne of waste daily to produce three Kw of electricity that lights up 120 street lamps.

‘’The fact that the public in Kadakkal was already agitated over garbage accumulation helped a great deal in seeing through the Biotech project,” M. Nazeer, an elected panchayat (local body) leader, told IPS.

Segregation into wet waste, dry biodegradable waste and recyclable solids like glass, metal and plastic is still done manually. For his biogas plant what is most valuable is wet waste – a rich slurry, which in Kadakkal includes blood and effluents from the local slaughter house, that is run through a pre-digester to optimise bacterial action.

Biotech’s ‘integrated waste recycling plant’ is equipped to deal with all types of waste generated by markets, slaughter houses, and restaurant kitchens. The success of the integrated plant is that it generates biogas for fuel, electricity for lighting and a valuable organic fertiliser called NPK (Nitrogen-Phosphorus-Potash mix). The plant incorporates no less than five technologies – biomethanisation, biocineration, leach beds, waste water treatment and vermicomposting – to complete the process.

While the biomethanisation unit handles easily degradable materials such as fish and meat, and food leftovers, the biocinerator is used to burn slow degrading wastes such as dry leaves, plants and paper. The plant uses leach bed technology to treat vegetables and green leaves. Anaerobic waste treatment is carried out in a special reactor and the final part of the process employs earthworms in a vermicompost unit.

“All this can be set up at a cost of just Rs.1.6 million (40,000 US dollars) as we know from experience at Kadakkal which became the first panchayat in the state to produce electricity from solid waste”. Das has now set up ten such plants across the state.

Explaining the secret of his technique Das said: “The usual treatment plants installed in fish markets and slaughter houses are not capable of dealing with dry leaves and plants. Treatment of fibre-rich vegetable matter creates scum in biogas plants, reducing their efficiency. Burning wastes using an incinerator creates pollution and is wasteful. The solution was to apply different technologies at appropriate stages.

At Kadakkal nothing is wasted. Water is extracted and recycled so that it can be sent back to the abattoirs to help flush them out. The electricity generated by the plant is used to run all the equipment, while the biogas produced by the methanisation unit provides all the fuel needed for the incinerator.

Biotech’s pride is the bio-waste treatment plant located at Sreekaryam, outside the state capital of Thiruvananthapuram. This efficient plant is capable of processing 250 kg of waste daily and produces three Kw of electricity.

A.P.Murali, president of the Sreekaryam panchayat, said : “Fish, fruit and vegetable waste generated by the market is fed into the treatment plant and converted into methane gas. Water used for the processing is recycled and fed back into the unit. The methane gas is passed through special biofilters and used to power a generator that supplies electricity to street lamps through a control panel. And the whole unit only cost Rs 700,000 (17,000 dollars).”

Biotech units thrive on human waste. Kumbalangi, in costal Ernakulam district, which has been declared a ‘model tourism village’ has 140 Biotech plants designed to run on waste from lavatories. Kumbalangi also has 800 plants that produce biogas from other wastes, set up with support from the central government and the tourism department.

Biotech plants have many advantages over the old centralised garbage disposal systems. There are no collection and transportation problems and all the maintenance can be done on site. Plants can be designed and scaled up or down according to the needs of the customer. The popular domestic version needs just one sq m of space to fit into and manages both solid and liquid waste simultaneously.

Vizhinjam panchayat, in which the international tourist destination of Kovalam is situated, now has 575 homes with garbage digesters installed and Biotech has a long list of orders.

J.Asuntha Mohan, president of Vizhinjam panchayat, said: “After installing the plants people here have been able to save substantial amounts of money against expenses on imported Liquefied Petroleum Gas (LPG) that is used for cooking. We are now trying to install a large recycling plant at Kovalam that can tackle the one tonne of garbage generated daily by the tourism industry.”

In its ‘Annual Economic Review’, the state government admits that only about 50 per cent of the 2,500 tonnes of waste generated per day in Kerala is collected for disposal. Everyday, about 1,200 tonnes of waste is left to decompose on road margins, drains, canals, water bodies and open space, the review said.

Well-known environmentalist and literary figure Sugathakumari told IPS that bio-waste digesters are a boon to Kerala. “Our local bodies have no pre-planning. They do not know how to utilise the bio-waste effectively while spending millions of dollars in the name of garbage removal,‘’ she said. “The integrated recycling plant solves the critical problem of garbage disposal while producing cooking gas, electricity and organic fertiliser. What more can you ask for?”

(*This story is part of a series of features on sustainable development by IPS – Inter Press Service, and IFEJ – the International Federation of Environmental Journalists.)

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