Lake in newly declared Bangalore bird sanctuary yet to undergo clean drive one year on

BANGALORE: The Puttenahalli lake at Yelahanka, which attracts over 100 species of birds, was declared a bird sanctuary last year. Conservationists thought this would improve the condition of the highly polluted lake. However, nothing has changed and the lake continues to receive a large inflow of sewage, repelling birds and humans likewise.

`Authorities Should Stop Evening Out the Lake bed'

STEPS: Lakes have natural slopes, with different zones of depth, leading to varied biodiversity. Earlier, sewage would be let out in the shallow part of the lake. Before it moved to the deeper parts, it would get naturally treated by sunshine. Authorities have evened out lake-beds in the name of development. This has to stop.

The water inlets to the lake are choked. They need to be reconnected to storm water drains.

Encroachments on storm water drains have be removed.

The pipes pumping polluted water out of the lake should be better designed and not prone to break or sink into the soft lake bed.

The rate at which the polluted water is pumped out should be increased to offset the large inflow of sewage.

The defunct sewage treatment plant close to the lake needs to be revived and used for treatment, instead of pumping water all the way to the plant at Yelahanka as proposed.

OFFICIAL LINE SP Rudramurthy, Chief Engineer at BWSSB, said a detailed project report for a secondary sewage treatment plant with 10 MLD capacity costing about Rs 17 crore has been prepared. “We are waiting for funds. It may be sourced through the Central Government's Mega Cities funding scheme,“ he said adding that in the two years until the plant is functional, sewage could be diverted to the Jakkur plant

`Allow Treated Sewage Water into the Lake'

STEPS: We should treat the sewage locally and economically, and let the treat ed water into the lake.

The main pollutants are nitrates and phosphorous, which are harmful and need to be removed.

A tertiary treatment plant which re moves these nutrients is energy and labour-intensive and costs a lot. In stead, letting the water treated by the secondary plant pass through a constructed wetland can remove 95% of these nutrients.

This water will go into the lake through a shallow algae pond which will help remove further nutrients.

This system has been successful in the Jakkur Lake and it can be replicated here within 18 months in a fraction of the cost of setting up a tertiary plant.