Urban waste management is one of the biggest challenges faced by the government authorities in modern times in developing countries and the issue is more critical in cities like Guwahati which have the historical disadvantage of unplanned growth. Bioremediation can play a vital role in such a scenario as it is not only economical but is also sustainable than other solid waste management technologies available.
Bioremediation is the process of using micro-organisms to neutralise or remove contamination from waste. This is done by introducing nutrients to stimulate the activity of bacteria in the waste or adding new bacteria to the soil. According to the Environmental Protection Agency (EPA), bioremediation is a treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances. This approach is currently applied to contain contaminants in soil, groundwater, surface water, and sediments including air.
Bioremediation is often seen in news during large-scale oil spills in any part of the world. It was used in the 2017 Ennore oil spills in Chennai to convert the oil sludge into non-toxic substances like sand. However it has a wide range of applications such as metal biosorption, bioventing (of gasoline and heavier hydrocarbons), bioaugmentation (cleaning of organic pollutants), land farming, composting, biofiltration (of contaminated groundwater) and various other applications which involve both in-situ (treatment of waste in the place of origin) and ex-situ (treatment of waste outside the place of origin) methods.
The scope of environmental bioremediation extends to inorganic substances (and areas) viz., arsenic, mercury, chromium, fluoride, cyanide, abandoned mines, fly ash disposed sites, engineered phytotreatment technologies, biological permeable barriers and organic substances like petroleum hydrocarbons, pesticides and explosives.
The advantage of bioremediation is that it uses no chemicals and can allow waste to be recycled. Biostimulation is a publicly accepted treatment of polluted soil because it is based upon natural processes. In situ bioremediation can result in complete degradation of pollutants into harmless or less hazardous products on site such as carbon dioxide, water and cellular biomass. In the modern world of rapid industrialisation and urbanisation, bioremediation is a sustainable and cheaper alternative to other technologies used for pollution mitigation.
The importance of bioremediation and micro-organisms on the path of achieving the sustainable development goals of the United Nations has been advocated by various environmental agencies as well as learned individuals. The Union Ministry of Environment & Forests, in a report (with Prof MNV Prasad) in 2011 has recognised bioremediation as an �invaluable tool box� for wider application in the realm of environmental protection.
Recently the Indore Municipality Corporation (IMC) has taken up a project of converting more than 12,00,000 tonnes of old dumped waste into soil which was lying in the dumping grounds for 70 to 80 years. The latest ranking of 2018 by Swachh Bharat Abhiyan announced Indore as the cleanest city in India for a second time.
In this process the old waste dumps are exposed to bioculture spray (it supplements useful bacteria for composting) and then left open for around 10-12 days allowing the decomposer micro-organisms to grow at a faster rate. High quality soil is obtained from this waste after going through the process of screening and sieving. This soil is utilised for afforestation and beautification by cultivating flowers. Moreover, the inert waste produced in the process is used for engineered landfilling.
This is a learning opportunity for the rest of the cities in India including Guwahati where solid waste dumping is creating a threat to the environment. At present, no proper disposal method is seen in the West Boragaon dumpsite of Guwahati. The municipal trucks simply carry the waste to the dumpsite and dispose it without any processing, which has now become a health risk to the local people with the resultant pollution of the air and water. There is prospect of converting the site into commercially utilisable land or city forest by following the IMC model.
Another such innovative initiative of IMC is the project of producing biofertiliser from the flowers used as nirmalis and malas in the temples by the process of bioremediation. There are many temples in Guwahati including the Kamakhya Mandir with high footfall where lots of flowers are offered by the devotees in the form of malas to the deities which can be processed by installing specific machines to produce biofertlizsers. This has two-way benefits of maintaining cleanliness as well as promoting organic farming.