Bharat Electronics Ltd, a defence PSU, is planning to set up a 10 MLD (million litres per day) sewage treatment plant to rejuvenate the Doddabommasandra Lake in Bengaluru at a cost of ₹13.5 crore.
The company has taken up the initiative as part of its corporate social responsibility (CSR) activities, in collaboration with the Karnataka Lake Conservation and Development Authority (KLCDA), Bruhat Bengaluru Mahanagara Palike (BBMP) and the Karnataka Revenue Department.
The foundation stone for the the plant will be laid on Saturday.
The lake contributes to the recharge of groundwater in the Doddabommasandra watershed region. It covers an area of 50.31 hectares (124.35 acres). The Doddabommasandra watershed region replenishes the ground water table of Vidyaranyapura, Govindayyanapalya, Doddabommasandra and Thindlu areas.
Rainfall is the only source of water for this lake, which is presently running dry. Even the water collected during the monsoons is lost due to percolation and evaporation. The lake is fast being depleted of its biodiversity and socio-ecological balance.
The company proposes to replenish the lake with waste water treated at the proposed plant and create a large water body rich in biodiversity.
“The sewage treatment plant will be designed on the latest Sequential Batch Reactor (SBR) technology. This is an advanced version of the well-established Activated Sludge Process of the Central Public Health and Environment Engineering Organisation (CPHEEO),” said a company official.
The sewage is fed into the SBR units for biological treatment involving organic matter degradation, nitrification, de-nitrification and phosphorous removal. The oxygen required for the process is supplied through Fine Bubble Diffused Aeration System with auto control of oxygen levels in the basin. The complete operation, including filling of sewage, aeration, sludge recirculation and decanting will be SCADA/PLC-controlled.
The treated water, after meeting Pollution Control Board norms, will be passed through the wetland comprising aquatic plants before flowing into the lake. BEL will construct the sewage treatment plant in the next 18 months and maintain it for a period of 20 years.
The benefits of such a plant include recharging of ground water, reduction of sewage load on the Bangalore Water Supply and Sewerage Board’s (BWSSB) treatment plant, improved groundwater table in areas in and around the lake which is home to a population of about 3 lakh, prevention of pollution due to untreated sewage, favourable conditions for the growth of fauna and flora, improved micro-climatic conditions leading to a balanced ecological system, and new recreational opportunities for fishing, bird watching and educational visits.