BENGALURU:It’s been close to two decades that one of the biggest water bodies in Bengaluru, the Bellandur Lake, has witnessed its now globally infamous frothing on and off. Only now, various stakeholders struggling to treat the lake have discovered the villain behind it, which may prove a major challenge to deal with — the 1.5-metre-thick layer of underwater sludge lining the entire lake bed spanning 900 acres due to careless discharge of effluent and untreated sewage from the neighbourhood over years, polluting the water body.
The infamous frothing of the lake resurfaced Tuesday morning following heavy overnight rains. Karnataka State Pollution Control Board (KSPCB) chairman Lakshman told The New Indian Express the lake-bed sludge, accumulated over a period of time varies from 1.2 to 1.5 metres in thickness. “The sludge contains nitrogen content, detergents and toxic effluents, which has to be removed. Every time it rains, froth resurfaces. We need to check the latest technology for removing the sludge. A global tender can be called. Unless this sludge is removed, the frothing will not stop. The STPs (sewage treatment plants) can only treat water and reduce frothing, but it will not be a permanent solution,’’ he said.
Right now, the work on installing an STP with 400 MLD capacity is going on. Lakshman said it is expected to be completed by 2020. “But this is not a permanent solution to stop the frothing permanently as there is sludge beneath the lake area. The lake is about 950 acres and 9.3 metres average depth.
Noted environmentalist A N Yellappa Reddy too felt that STPs will not help much. It needs to be treated from all sides. “A complete Environmental Impact Assessment (EIA) should be done of the sludge and water. There are many available technologies, which are long-term. The Bellandur frothing cannot be removed any time soon,’’ he said, adding that the sludge is accumulated over the past 40 years. This resulted in frothing. The first time that frothing was witnessed was in 2000. But for the past three-four years, frothing is witnessed more frequently and in February 2018, there was also a fire along with the frothing.
Additional Chief Secretary (Urban Development Department) Mahendra Jain said as a permanent measure they will install culverts so that treated water will not flow over the waste, but through the bottom level pipes.
After the February fire alongside frothing, the National Green Tribunal (NGT) issued show-cause notices to various agencies including BBMP, BDA, BWSSB, Karnataka Lake Development Authority, KSPCB and other agencies, asking them why they should not be prosecuted over the frothing in the lake.