Indian landfills — a source of microplastics?

Subject: Environment

Section: Pollution

Context:

If the landfills are not scientifically constructed and operated, they can act as a hub of numerous kinds of contaminants including plastics.

Details:

Organic waste such as food waste and greens at landfill sites decomposes faster with microbial activities under aerobic and predominantly anaerobic conditions, producing leachate and gaseous emissions.
Plastic items are mainly non-biodegradable and remain intact in landfills.
The main sources of plastic in landfills are disposable diapers, sanitary pads, carry bags, multi-layered packaging items, packaging sheets, container bottles, polyvinyl chloride (PVC) pipes, footwear, disposable cups and plastic utensils.

Formation of microplastics:

Microplastics are plastics of size ranging from greater than or equal to 1 micrometre to less than 5 millimetres and can be categorised as primary microplastics (virgin or manufactured) and secondary microplastics (emitted by the degradation of larger plastics).
Inside a landfill or a dumpsite, complex biochemical reactions result in temperature fluctuations, high salinity, low pH and the generation of gases such as methane, carbon monoxide, carbon dioxide, ammonia and hydrogen sulphide.
These contribute to creating an environment conducive to the disintegration of plastic items into smaller pieces.
In addition, physical processes such as weathering of larger plastic particles through photo-degradation, thermal degradation, mechanical fragmentation and biodegradation are also responsible for the formation of microplastics.
They enter landfills primarily through waste disposal of personal care products and pharmaceuticals, artificial textiles and raw industrial products, as well as through improper management practices such as the lack of a perimeter barrier around the landfills and the use of improper waste cover materials.
Source of microplastics: Nylon, pellets, foam, fragments, fibres / polyvinyl chloride and polyethene.

Solution:

The Solid Waste Management Rules (2016), Plastic Waste Management (Amendment) Rules, 2022 and the recent ban on single-use plastics and extended producer responsibility policy in India ensure that plastic waste generation is minimised and prohibits the cities from disposing of any combustible waste including plastics into the landfills.