New Delhi: The city's landfill sites overflowing with garbage are not only becoming health hazards but also a major source of methane emission known to have a global warming potential, a government study says.
Three major landfill sites -- Bhalswa, Gazipur and Okhla -- are receiving a total 5,400 tonnes per day (TPD) of garbage from all the 12 zones of Delhi including NDMC and Delhi Cantonment Board. The city produces over 6,000 tonnes of solid waste daily.
"However, in the absence of lack of any scientific management in place, anaerobic decomposition of the organic content of the waste in them results in landfill gas generation comprising methane, one of the important greenhouse gas (GHG) with a global warming potential," it says.
The report "Inventorisation of GHG: Sources and Sinks in Delhi" prepared by Delhi University on behalf of the state government gives a comprehensive details of carbon footprint of various sectors besides the dumping yards which have exhausted their life span.
Ghazipur landfill site in East Delhi which was commissioned in 1984, receives maximum waste at 2,200 TPD including construction and demolition waste. The waste accumulation has reached a maximum height of about 30.5 metres at a few places and an average height of about 25.5 metres above ground level, the report says.
The site which are owned by MCD does not have proper landfill management system expect daily spreading and compunction of waste, it says.
"Presence of poultry and fish market and slaughter house towards the northern boundary of the landfill site, has led to a significant amount of animal waste being dumped here," the report says calling for immediate remedial measures.
Bhalswa landfill site in North Delhi, commissioned in 1992, spread over 26.22 hactares gets 1,500 tonnes of municipal waste plus 700 tons of construction and demolition waste by more than 500 trucks.
After detailed study based on total solid waste reaching the site annually and the waste character, the researchers estimated methane emission to be 74.60 kilotonnes from the three landfill sites in 2008 with Bhalswa landfill site contributing maximum methane of 38.2 kilotonnes followed by Ghazipur (22.64 KT) and Okhla (13.76 KT).
Average concentration of methane was exceptionally highest at Ghazipur at 334236 PPB (Parts Per Billion) due to the larger amount of animal waste coming in from poultry market, fish market and slaughter house followed by Okhala (89858 PPB) and Bhalswa (28119 PPB).
"As far as Co2 concentration was concerned, it was highest at 651 PPM (Parts Per Million) at Ghazipur which is mainly due to burning of waste at the dumping site while Okhala and Bhalswa recorded CO2 concentration of 576 PPM and 537 PPM respectively," says the report.