Why do landfills catch fire during summers?
How should a municipality respond if a landfill does catch fire? What are some of the permanent solutions?
The story so far:
The Kochi landfill site around Brahmapuram that caught fire earlier this month is a stark reminder that Indian cities need to be prepared for more such incidents as summer approaches. Preventing such fires require long-term measures, including thorough and sustained interventions from municipalities.
How do landfills catch fire?
India’s municipalities have been collecting more than 95% of the waste generated in cities but the efficiency of waste-processing is 30-40% at best. Municipal solid waste consists of about 60% biodegradable material, 25% non-biodegradable material and 15% inert materials, like silt and stone. Municipalities are expected to process the wet and dry waste separately and to have the recovered by-products recycled. Unfortunately, the rate of processing in India’s cities is far lower than the rate of waste generation, so unprocessed waste remains in open landfills for long periods of time. This openly disposed waste includes flammable material like low-quality plastics, which have a relatively higher calorific value of about 2,500-3,000 kcal/kg, and rags and clothes. In summer, the biodegradable fraction composts much faster, increasing the temperature of the heap to beyond 70-80°C. A higher temperature coupled with flammable materials is the perfect situation for a landfill to catch fire. Some fires go on for months.
Is there a permanent solution?
There are two possible permanent solutions to manage landfill fires. The first solution is to completely cap the material using soil, and close landfills in a scientific manner. This solution is unsuitable in the Indian context, as the land can’t be used again for other purposes. Closed landfills have specific standard operating procedures, including managing the methane emissions. The second solution is to clear the piles of waste through bioremediation — excavate old waste and use automated sieving machines to segregate the flammable refuse-derived fuel (RDF) (plastics, rags, clothes, etc.) from biodegradable material. The recovered RDF can be sent to cement kilns as fuel, while the bio-soil can be distributed to farmers to enrich soil. The inert fraction will have to be landfilled. However, implementing a bioremediation project usually takes up to two or three years, necessitating a short-term solution for summertime landfill fires.
What are some immediate measures?
Landfill sites span 20-30 acres and have different kinds of waste. The first immediate action is to divide a site into blocks depending on the nature of the waste. At each site, blocks with fresh waste should be separated from blocks with flammable material. Blocks that have been capped using soil are less likely to catch fire, so portions like these should also be separated out. The different blocks should ideally be separated using a drain or soil bund and a layer of soil should cap each block. This reduces the chance of fires spreading across blocks within the same landfill. Next, the most vulnerable part of the landfill — the portion with lots of plastics and cloth — should be capped with soil. The fresh-waste block shouldn’t be capped but enough moisture should be provided by sprinkling water and the material should be turned regularly for aeration, which helps cool the waste heap. Once a site has been divided into blocks, the landfill operator should classify incoming waste on arrival to the site, and dispose them in designated blocks rather than dumping mixed fractions. Already segregated non-recyclable and non-biodegradable waste should be sent to cement kilns instead of being allowed to accumulate. Dry grass material and dry trees from the site should also be cleared immediately.
While these measures can help reduce the fires’ damage, they’re far from ideal and not long-term solutions. The permanent and essential solution is to ensure cities have a systematic waste-processing system where wet and dry waste are processed separately and their byproducts treated accordingly.
Pushkara S.V. is a practitioner at the Indian Institute for Human Settlements
India’s municipalities have been collecting more than 95% of the waste generated in cities but the efficiency of waste-processing is 30-40% at best. This openly disposed waste includes flammable material like low-quality plastics.
There are two possible permanent solutions to manage landfill fires. The first solution is to completely cap the material using soil, and close landfills in a scientific manner. The second solution is to clear the piles of waste through bioremediation.
Preventing such fires require long-term measures, including thorough and sustained interventions from municipalities.