A smart fix for city's trash trouble

Bengaluru’s residents need to wake up to the fact that our ‘Garden City’ has become a ‘Garbage City’. Even the tonier areas of Indiranagar and Koramangala have piles of garbage everywhere. Not surprising, considering the city generates 5,500-6,000 tonnes per day (TPD) of Municipal Solid Waste (MSW) according to Bruhat Bengaluru Mahanagara Palike (BBMP) records. This goes into seven landfills on the outskirts of the city, decomposing and releasing greenhouse gases, leaching toxins into soil and water supplies, causing massive environmental and health disasters. When one landfill is full or the neighbourhood objects vehemently, the BBMP merely finds another landfill. With the increase in urbanisation and changes in food habits and lifestyle, the MSW generated has undergone a change of variation in waste composition. A ResearchGate study states that Bengaluru’s waste composition is 57 per cent dry and combustible waste, suitable for incineration, the balance being organic and biodegradable waste.

Incineration in a WTE (waste-to-energy) plant reduces the quantum of MSW while simultaneously recovering energy, effectively solving two problems: waste management and energy production without depletion of fossil fuels. When correctly maintained and operated, WTE plants use MSW converted into Refuse-Derived Fuel (RDF) which is fed into a boiler for combustion. With a fully integrated control system ensuring stability and efficiency, the energy released is used to produce super-heated steam for turning the blades of a turbine generator which generates electricity. Flue gas cleaning systems and controlled combustion ensure emission standards are maintained. WTE plants do not pose any critical occupational health hazard to the general public, any more than other waste management solutions like direct land-filling of untreated wastes, attests a WHO report.

Concerns about environmental pollution, toxicity, smoke, ash deposits and the effect on health leading to cancer do exist. In fact, the emission of dioxins and furans is of special concern in Western Europe where hundreds of WTEs are already in operation, but combustion processes like garden bonfires, steel mills and crematoria leave similar traces of dioxins and furans. During the last decades, emission norms have become more rigorous with the introduction of enhanced gas cleaning equipment standards, and the industry is responding. Soon, WTE plants can be located near densely populated areas, close to where waste is generated, to reduce the need for transportation as compared to landfills that necessarily have to be located far away from urban spaces, adds the WHO report.

An air-cooled stoker type WTE incinerator is proven technology — divided into three processes, a dry process evaporates the water content in the waste, the combustion process powerfully burns the dried waste and the post-combustion process completely burns it out. With a complete and efficient modern air pollution control system that includes the use of a degasser, an electrostatic precipitator, a flue gas cleaning system, a waste water treatment plant and a stack, the demands of both technical performance and environmental guidelines are strictly adhered to.

Jabalpur, a beneficiary of India’s smart city programme, has a successful WTE plant operating since March 2018. The city generates 800 TPD of MSW, which would otherwise go into landfills but for a 11.5 MW, Hitachi-Zosen incinerator that ensures gases released from combustion generate steam, producing electricity. The pollutants including flue gas are treated prior to emission complying with European standards. One challenge Jabalpur initially faced was the municipal corporation’s inability to collect the required RDF, a
gap that was eventually filled by transporting waste from nearby Nagpur to meet the difference, a problem Bengaluru will definitely not encounter.

Bengaluru’s first WTE, identical to Jabalpur’s plant, is being set up by the Karnataka Power Corporation Limited (KPCL) and the BBMP in Bidadi. The BBMP has committed to supplying 600 TPD of RDF with a guaranteed calorific value of 2,700 kCal/kg or more to the plant, the guarantee absolutely essential to counter the problem of low calorific content of the city’s waste. Given that the KPCL is engaged in running power plants since the 1970s, and the WTE configuration is similar to a successful WTE plant at Jabalpur, the Bidadi plant should be equally successful when it becomes operational in September 2023.

A city that generates 6,000 TPD, Bengaluru requires six plants of similar capacity taking into account the 57 per cent dry waste composition.

(The writer is former Executive Director and Member, Board of Directors, BEML)