Waste-to-Energy plants that use solid waste as feedstock pose threat to environment

Waste-to-Energy plants that use solid waste as feedstock pose threat to environment

Environment

News: The article discusses WtE plants working in India and their challenges.

Facts:

• WtE plants process municipal solid waste to generate electricity through incineration.
• There are 5 municipal WtE plants operational in India with a total capacity of 66.4MW electricity per day, of which 52MW per day is generated in Delhi by its three existing plants.

Problems associated with WtE plants in India:

• WtE plants in India burn mixed unsegregated waste.
• The presence of chlorinated hydrocarbons, like PVC, in burnt waste results in the release of dioxins and furans when the waste is burnt at less than 850 degree C.
• Dioxins and furans are known to be carcinogenic and can lead to impairment of immune, endocrine, nervous and reproductive systems.
• Even when incineration takes place under optimal conditions, large amounts of flue gases, mercury vapour and lead compounds are released and 30% residue is slag (bottom ash) and fly ash (particulate matter), which are serious pollutants of air and water.
• Solid Waste Management Rules 2016 require phasing out of PVC in incinerators by April 2018. But it is impossible to identify and remove PVC beverage labels, for example, from mixed waste streams.
• WtE plants in India are also inefficient in generating energy due to very high biodegradable (wet) waste content (up to 60 and 70%), compared with 30% in the West. This gives our waste a high moisture content and low calorific value.
• Municipal governments use compacters to reduce the transport cost of the waste which compresses the waste and makes even gross segregation at the plant site impossible.

What can be done?

• Wet and dry wastes should not be mixed so that only non-compostable and non-recyclable wastes with at least 1,500 kcal/kg should reach WtE plants. Such waste comprises only 10 to 15 per cent of the total waste.
• Municipal authorities should be made aware of the harmful effects of WtE technologies and should not be allowed unless the waste offered meets the criterion specified by the SWM Rules.
• There should be adequate use of activated charcoal to filter out dioxins, furans and mercury from the emissions in plants.
• For ensuring that waste is not mixed at the source of generation and handling of waste is in unmixed streams, there should be strict penalties for non-compliance.
• Exploration of low cost options such as composting and bio-methanation should be done.