By Sayantan Sur
On a bleak wintertide morning in January, our story begins with a black taxi and a somnolent rider. The taxi was racing through a maze of concrete towards the southern part of the city when out of the blue, the silhouette of a towering mountain appeared. With a large flock of wings dancing around its crest, the mountain looked surreal. One would naturally be stupefied to come across this elevation as Delhi is supposed to be flat as a pancake. As we closed in, my initial shock was instantly replaced by a strong sense of revulsion, for the mountain turned out to be a ginormous pile of rubbish. This reeking pile, I would later find out, is infamously known as the mountain of garbage.
The mountain is currently as tall as the majestic Taj Mahal, and would soon outgrow the mausoleum. On blazing summer days, spontaneous fires erupt from the methane released from the dump. Encircling its slope, is a small slum of rag-pickers. The local inhabitants who continually breathe in the putrid air often develop severe respiratory diseases, allergies, and asthma. Discarded tires at the dumpsite accumulate rain-water and transform into a haven for mosquitoes. This dump at Ghazipur was instated in 1984 and was to be closed in 2002 when it had reached its capacity, but evidently, that did not happen. The mountain and its ailing people sum up the out-and-out failure of the capital’s waste management system and its lack of operational efficiency.
On average, Delhi produces 10,000 tonnes of waste per day, and less than half of it gets segregated. About 50% of this waste is composed of organic materials, which for the most part comes from individual households. To treat this heap of organic waste, Delhi has only two operational composting and zero vermi-composting plants. The number of such facilities undoubtedly need to be increased. Although organic wastes account for a large fraction of the total waste, it imposes a lesser threat than other inorganic wastes such as plastic.
Plastic wastes make up just about 10% of the total municipal solid waste in Delhi, despite the current blanket-ban on 50-micron plastics. Three fourth of the household garbages are wrapped in single-use polythene bags, which eventually end up in landfill sites. Delhi currently generates the largest quantity of plastic waste in India, which is truthfully shameful. These plastics are practically impossible to segregate at the landfill sites due to the lack of advanced equipment. The only recycling presently being done is by the rag-pickers, who risk their lives to rummage through the rotten dumps and sell the collected plastics to intermediary dealers.
Other countries, however, have addressed this very problem by using advanced scientific methods. Commercially available sorting machines can easily classify the plastic wastes from other garbages, which uncomplicate the task of recycling. These machines employ basic spectroscopy and x-ray techniques to perform macro-sorting, which is far more efficient than manual sorting. Macro-sorting involves the separation of plastic bottles and containers, while micro-sorting deals with smaller bits, such as chopped plastic flakes. The sink-float technique is one of the major methods used to perform micro-sorting; here the materials are deposited in a water-filled tank and subsequently, the lighter materials start to float while the heavy materials sink. This technique works only when the materials have different densities. The plastic wastes can also be used to fabricate usable products, such as hydrogen and carbon-nanotubes, by using a process called two-step pyrolysis. This process uses Ni-Fe (Nickel and Iron) as a catalyst under extreme temperatures, to produce high yields of hydrogen gas. This thermochemical method is remarkably energy-efficient and can be easily practiced to recycle our plastic wastes.
An alternative way to get rid of plastics is through bioremediation. It involves the usage of different microorganisms, which can consume and degrade certain environmental pollutants. Last year, a paper published in the journal, Environmental Pollution has discovered an entirely new species of plastic-eating bacteria (Ji et al. Env. Pol. 258, 113793; 2020). This bacteria, Mycobacterium neoaurum, is the first known bacteria identified to have the ability to degrade 2,6-DMP (2,6-dimethylphenol), which is a widely used plastic monomer. Consequently, M. neoaurum might prove to be a key candidate for the bioremediation of 2,6-DMP-contaminated areas.
Corresponding to this, another paper published in, Science of the Total Environment has unearthed a plastic-eating super worm in China (Yang et al. Sci Total Environ. 708, 135233; 2020) . The larvae of the worm, Zophobas atratus, was proven to be capable of degrading and mineralizing polystyrene. The worms were shown to survive near about a month on the Styrofoam diet alone. Each super worm was estimated to devour 0.58 mg Styrofoam per day, which is four times more than what mealworms can eat. These new findings can change the currents ways of recycling plastic but we have to bear in mind that these scientific methods can only be used when our waste is properly segregated and disposed of in the first place; if the biological wastes are mixed with inorganic wastes, then they become unusable for future use.
The present-day segregation and sorting happen under extremely hazardous conditions and its effectiveness is reasonably low as only valuable discards are segregated from the dumpsite which guarantees a comparatively greater economic benefit in the recycling market. So, it becomes our duty as civilized citizens to ensure that we sort our household trash at our homes and then only it will have a domino effect on the waste management process.
The mountain of garbage is not only a physical body, but it is a metaphor that can be applied to any city with poor garbage disposal facilities. Luckily for us, the final act is yet to be written, and only time will reveal that story.
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Sayantan Sur is a doctoral fellow at the University of Delhi. He has published numerous scientific articles and has won 2019 AWSAR award for articulating best science story.
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