Indian landfills — a source of microplastics?

Scientific landfills are considered containment systems that isolate waste from the surrounding environment. On the contrary, if the landfills are not scientifically constructed and operated, they can act as a hub of numerous kinds of contaminants including plastics. 

Plastic waste dumping into landfills and dumpsites around the world is a global concern, causing environmental and human health hazards. 

Microplastics in soil ecosystem from landfills

Source: Sekar, V., & Sundaram, B. (2023). Preliminary evidence of microplastics in landfill leachate, Hyderabad, India. Process Safety and Environmental Protection, 175, 369-376.

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. 

Plastics items, however, are mainly non-biodegradable in nature and remains 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. 

Inside a landfill or a dumpsite, complex biochemical reactions result in temperature fluctuations ranging from 30-60 degrees Celsius, high salinity, low pH and generation of gases such as methane, carbon monoxide, carbon dioxide, ammonia and hydrogen sulphide. These contribute in creating an environment conducive for 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 formation of microplastics.

Microplastics are typically the plastics of size ranging from greater than or equal to 1 micrometre to less than 5 millimetre and can be categorised as primary microplastics (virgin or manufactured) and secondary microplastics (emitted by the degradation of larger plastics). 

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 lack of a perimeter barrier around the landfills and the use of improper waste cover materials.

Recently, a study conducted by the NIT Andhra Pradesh reported the presence of microplastics concentrations in landfill leachate in Hyderabad, ranging from 9-21 items per litre. The most common microplastic shape was fiber (83 per cent), followed by fragment (11 per cent), film (3 per cent) and foam (2 per cent). 

The microplastic colours found in leachate were yellow (35 per cent), transparent (16 per cent), purple (15 per cent), blue (11 per cent), pink (8 per cent), white (6 per cent), black (3 per cent), green (2 per cent) and orange (1 per cent). 

From the chemical analysis, the predominant polymers detected were low-density polyethylene, polypropylene, polyterethalate, cellulose acetate and nitrile.  

Source: Sekar, V., & Sundaram, B. (2023). Preliminary evidence of microplastics in landfill leachate, Hyderabad, India. Process Safety and Environmental Protection, 175, 369-376

Uncontrollable plastic disposal in landfills is the primary source of plastic pollution, according to one of the authors of the study, VijayKumar S. As environmental degradation takes its toll, larger plastic debris in landfills undergo fragmentation, transforming into microplastics that pervade and contaminate the environment.

In 2021, a study conducted by the Institute for Ocean Management, Anna University, Chennai, Tamil Nadu identified, characterised and quantified the microplastics in groundwater samples around Perungudi and Kodungaiyur solid waste dumpsites in South India.

The groundwater samples were found to be contaminated with microplastic particles in the range of 2-80 items per litre with coloured particles including white (38 per cent), black (27 per cent), green (8 per cent), red (18 per cent), blue (6 per cent) and yellow (2 per cent). 

The polymer type was found to occur in the following order: Nylon (70 per cent), pellets (18 per cent), foam (6 per cent), fragments (3 per cent), fibers / polyvinyl chloride (2 per cent) and polythene (1 per cent). 

In both sampling sites, 90 per cent of microplastics are derived from the buried plastics and waste fragmentation, predominantly of polypropylene and polystyrene. 

Identified microplastics under microscope

Source: Sekar, V., & Sundaram, B. (2023). Preliminary evidence of microplastics in landfill leachate, Hyderabad, India. Process Safety and Environmental Protection, 175, 369-376.

Both the studies are very crucial as they present the preliminary evidence of microplastics in the Indian dumpsites which can pose a serious impact on the surrounding environment. To effectively combat microplastics contamination originating from landfills, a multifaceted policy approach is imperative, specifically focusing on implementation of waste management policies, efficient collection and treatment to limit the influx of plastics into Indian landfills. 

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

In addition, robust monitoring and enforcement, including penalties for non-compliance, is vital to ensure adherence to waste management regulations. Regulations governing scientific landfill design, with an emphasis on advanced containment and liner systems and remediation of existing open dumpsites in India are essential to prevent leachate from disseminating microplastics into the environment. 

Investing in research, incentivising innovation and encouraging a circular economy approach can further strengthen policy frameworks, promoting a comprehensive strategy to stop microplastics contamination from landfills and dumpsites in India.