MCD to set up two plants to treat leachate at Bhalswa, Ghazipur

A senior MCD official said that the two plants will have the capacity of treating 100 kilolitre per day (KLD) of polluted leachate

In an attempt to tackle the problem of highly contaminated leachate water percolating through the dump sites, the Municipal Corporation of Delhi (MCD) has initiated the process of setting up of two leachate treatment plants in its Bhalswa and Ghazipur sanitary landfill sites, officials aware of the matter said on Sunday.

The Bhalswa and Ghazipur landfill sites are likely to remain active till at least 2027. (HT Archive)

Leachate is formed when rain water filters through wastes at a landfill. When this liquid comes in contact with buried wastes, it leaches or draws out chemicals or constituents from those wastes. It is one of the key environmental hazards due to unplanned landfill sites and may lead to groundwater contamination.

A senior MCD official said that the two plants will have the capacity of treating 100 kilolitre per day (KLD) of polluted leachate. “Each of these plants will cost around ₹3 crore and a notice inviting tenders will be issued soon. A plant has not been proposed for the Okhla landfill as no fresh waste is being dumped at the site since the last one year,” the official added.

“The new engineered landfill site that is coming up at Tehkhand has liners and base layers for collection of leachate, but the three older landfills have no such mechanism. The treatment plants will come up along with leachate collection pipes and associated system,” the official added.

In April last year, the solid waste management committee constituted by the National Green Tribunal (NGT) ordered that MCD should ensure treatment of leachate as per prescribed standards by providing sufficient capacity of treatment facility. It should also submit details on the quantity of leachate discharged and leachate treatment plants that are sufficient to treat the entire leachate generated at the dumpsites. MCD has assessed that 100KLD facilities will be enough to tackle the problem.

Earlier in April 2022, NGT had imposed a fine of ₹450 crore as environmental compensation for improper management of solid municipal waste at the landfill sites, noting that the sites were leading to groundwater contamination as well as continuous emission of methane and other harmful gases. The study conducted by experts from the National Environmental Engineering Research Institute, Central Pollution Control Board and IIT-Delhi assessed that ecological damage to the tune of ₹155.9 crore has been caused by Bhalswa landfill, ₹151.1 crore in Okhla and ₹142.5 crore in Ghazipur.

The experts considered factors such as leachate generated over time and legacy waste accumulated at landfills and violations of solid waste management rules to calculate the damage caused to the environment.

“High level of chemical oxygen demand (COD) and iron reported in groundwater at all the three sites may be due to leachate from the dumpsite. Chlorides, total dissolved solids, total soluble solids and turbidity was reported in surface water body located within a radius of 0-1 km from Bhalswa site, which may be due to leachate from the dumpsite,” the committee had said in its groundwater and water analysis.

COD is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. The most common application of COD is to quantify the amount of oxidisable pollutants found in surface water (lakes and rivers) or wastewater.

Leachate was found to be reaching as far as 3 to 5 km away from Ghazipur, with high COD values reported at Sanjay Lake too, the report said.

“Even a small amount of landfill leachate and highly concentrated heavy metals can pollute a large volume of surface as well as groundwater, making it unfit for consumption. These leachates and heavy metals can ultimately enter food chain and in the long run, can affect natural and human resources,” the study said.

Expert comment to be added