GS3: Environment | Conservation, environmental pollution and degradation, environmental impact assessment

Why in news?

The Waste-to-Energy (WtE) plants that use solid waste as feedstock pose threat to environment as per the recent study.

Highlights:

• 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 66.4 MW electricity per day, of which 52MW per day is generated in Delhi by its three existing plants.

The problem:

• WtE plants in India burn mixed waste.
• The presence of chlorinated hydrocarbons like PVC 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. They are extremely difficult and costly to measure, as the experience of Okhla shows. The large amounts of flue gases, mercury vapour and lead compounds are released.
• About 30 per cent residue from incineration in the form of slag (bottom ash) and fly ash (particulate matter), which are also known to be serious pollutants of air and water.

Measures taken:

Solid Waste Management (SWM) Rules 2016 require that PVC be phased out in incinerators by April 2018. SWM policy requires that 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. As a preventive measure, the National Green Tribunal (NGT) directed the Ministry of Environment and Forests to consider the phase out of such single-use short-life PVC and issue appropriate directions by July 2017.

Way forward:

• Wet and dry wastes segregation at source
• Awareness about the harmful effects of WtE technologies
• There should be adequate use of activated charcoal to filter out dioxins, furans and mercury from the emissions in plants.
• Strict penalties for non-compliance.
• Exploration of low-cost options such as composting and bio-methanation
• Proper implementation of SWM policy
• Follow NGT directions