Bellandur Lake
The plant will prevent nearly 120 MLD of untreated sewage from entering the lake.
CM of Karnataka‏/Twitter

In a first for the city, Bengaluru now has a Sewage Treatment Plant (STP) that can generate power through biogas. The power generated will take care of 50% of the plant's consumption.

The STP, which was inaugurated on Monday, has a capacity of 60-million-litres-a-day (MLD). It will come as a major helping hand to authorities struggling to clean the massively polluted Bellandur lake.

The plant will prevent 120 MLD of sewage from entering the lake.

"The entire sewage generated from Kanakpura Road to Sarjapur Road (1/5th of Bengaluru's population) is conveyed to this Plant for treatment through the Agaram ISPS. This will avoid the entry of 120 MLD untreated sewage into the Bellandur Lake," the Bangalore Water Supply and Sewerage Board (BWSSB) said in a statement.

The National Green Tribunal had ordered the state government on April 18 to clean Bellandur lake within a month's time. But authorities say that a month is simply not enough to clean the 1000-acre lake and that the task may take nearly 3 years to complete.

Bellandur lake caught fire in February

Located in the Koramangala-Challaghatta Valley, the sewage treatment plant was inaugurated by Chief Minister Siddaramaiah on Monday. This is one of the ten STPs taken up under the Cauvery Water Supply Scheme Stage IV Phase II project.

Treated sewage water from the plant will be diverted to lakes in and around the drought-hit Kolar district.

"The raw sewage (entering the plant) has (a) Biochemical Oxygen demand (BOD) of around 300ppm & amp, and Chemical Oxygen Demand (COD) of around 500ppm. This plant will treat and discharge the sewage which will have (a) BOD of 15ppm & amp and COD of 100ppm,” the BWSSB release said.

Biochemical Oxygen Demand (BOD) is the oxygen level needed for marine life to sustain. BOD is usually used as a parameter to estimate the effect of untreated water on the environment. Greater BOD points towards fast depleting oxygen levels in the water body, which means that less oxygen is available to marine organisms.

Chemical Oxygen Demand (COD) is a measurement that indicates the amount of oxygen needed to oxidise organic matter in water. When BOD and COD levels reduce, decomposition is faster and the lake gets cleaned.

“As the nutrient removal is part of the treatment process, environmental friendly effluent is safely discharged for filling the lakes in and around Kolar district through the work taken up by Minor Irrigation Department," the release added.

The plant was set up at a cost of Rs 205 crores and took three years to be built. Special custom-made equipment was imported, including gas engines from GE, Austria, blowers from Howden, Hong Kong, MLR pumps from Suzler, Norway, diffusers from EDI, USA and submersible mixers from Xylem, Sweden.

"The plant has started functioning but will take some time to stabilise. It will take around 15-20 days for it to discharge the first round of treated water. After that it will be a continuous process," Kemparamaiah, BWSSB Engineer-in-Chief, said.