BWSSB's 100% sewage treatment plan: Many more miles to go

BWSSB needs to work on expanding its capacity and network to treat sewage, while the technology needs to be upgraded to improve quality

The southern side of Arakere lake off Bannerghatta road has been receiving sewage for a long time now, despite the area being covered by the Bangalore Water Supply and Sewerage Board (BWSSB)'s sewage network. Many Lokayukta hearings have yielded no satisfactory result for the lake's water quality.

"Hulimavu main road has BWSSB sewage lines, but this is at a higher elevation than some of the houses. This might force some of the houses here to go for septic tanks or just leave the sewage to the lake," says Subbu Hegde, a member of Arakere Neighbourhood Improvement Trust. He adds that even the stormwater drain inlet in the southwest corner of the lake brings sewage into the lake.

This is just one of the many examples of the city's sewage going where it should not. The Bangalore Water Supply and Sewerage Board (BWSSB) plans to treat the city's all sewage by 2025. But it comes with many challenges including its network and water quality.

"The STPs which are already operational have the capacity to process a large quantity of sewage. However, BWSSB is not collecting all the sewage and hence the focus now should be on building a better network to collect all the sewage generated in the city," said Vishwanath S, founder of Biome Trust and the Rainwater Harvesting Club.

Read | Faecal coliform plagues BWSSB’s treated water

Jayaram N, BWSSB Chairperson, acknowledged that the outer areas were a matter of concern. “In the core areas, the sewage network is good and we are able to process most of the sewage collected. However, the concept of sewage collection and processing was not prevalent in the 110 villages on the city’s periphery. To process the sewage generated there is a challenge,” he added.

Expanding the network

The BWSSB is now laying sewage lines in the 110 villages added to BBMP limits in the 2008 expansion. There is also a plan to set up a 125-MLD STP, but officials are not sure if that would be sufficient.

While the BWSSB has set up 36 Sewage Treatment Plants (STP) across the city, not all of them run to their capacity. Of the capacity to process 1527.5 Million Litres a Day(MLD), BWSSB is only processing close to 1,200 MLD.

“The amount of sewage generated is usually 80% of the city’s water needs. While we receive 1,400 MLD of Cauvery water, another 500 MLD is obtained from various other sources such as borewells. Considering this, we aim to process at least 1,600 MLD sewage in the next few years,” explained Jayaram.

“Considering the rate at which the city is growing, we estimate that we may have to set up plants to treat another 300-400 MLD of excess sewage,” a senior BWSSB official said.

Most of the treated water is either let into the lakes or pumped out to Kolar and Chikkaballapur for irrigation purposes. The BWSSB is exploring opportunities to supply treated water to commercial and industrial establishments.

"The processed water from Yelahanka STP is being supplied to the Bangalore International Airport where it is reused. From the Jakkur STP, water is being pumped out to Karnataka Power Corporation Limited (KPCL)," said Gangadhar B C, BWSSB Chief Engineer, Waste Water Management.

Water quality still a concern

While activists have pointed out that the sub-standard quality of treated water being let into lakes has resulted in fish kill and pollution in many lakes, farmers from Kolar and Chikkaballapur are also unhappy with the quality of treated water.

While Kolar receives close to 350 MLD, Chikkaballapura receives 150 MLD, and Anekal is supplied with 50-60 MLD of secondary treated water.

"BWSSB is only trying to abide by the NGT order to reuse the treated water and hence pumping it for agricultural purposes and conveniently neglects the guidelines by National Green Tribunal (NGT) on the quality of the treated water. Secondary treated water being supplied is not up to the mark and cannot be used for agricultural purposes. We have been demanding that the BWSSB pump out tertiary treated water instead," said Anjaneya Reddy, President of Shashwatha Neeravari Horata Samithi and one of the petitioners in the PIL filed at the Karnataka High Court requesting better water quality.

Ramu Shivanna, a farmer from Kolar, said that the agricultural produce from Kolar is now considered inferior since it is grown using treated water which is not up to the quality standards.

"At the Lakshmi Sagara lake where the treated water first enters Kolar, frothing was observed, indicating the poor quality of water being supplied," he said.

Farmers also pointed out that the BWSSB had failed to manage water flow and the treated water was now entering many lakes which are used by the locals as a source of drinking water.

"There is a need to study the links between lakes and water flow. Treated water entering lakes which are used as a drinking water source results in the spread of diseases," Anjaneya Reddy said.

A senior BWSSB official acknowledged that a few STPs were not up to the NGT standards, and the process of upgrading 20 STPs to meet the NGT standards is on.