High turbidity at TK Halli treatment plant

The release of water from the Krishna Raja Sagar (KRS) and Kabini dams has not just flooded the river basin, but also increased the turbidity level in the water drawn by the BWSSB to supply to the city.

This resulted in the board supplying about 100 MLD (million litres of water per day) short of its total supply for one day recently.

Turbidity is the number of particles present in the water. Its measurement is a key test to check the water quality.

According to the BWSSB officials, the normal turbidity of raw water received at the treatment plant at Thorekadanahalli (TK Halli) in Malavalli taluk of Mandya district was just around 100 NTU (Nephelometric Turbidity Units). But a record level of 230 NTU was found in the raw water on Sunday night.

The crest gates of the KRS dam were lifted on the afternoon of July 14 and by Sunday night, the high turbidity of Cauvery water reached the source point at TK Halli plant from where the BWSSB draws raw water to be treated and pumped to the city.

BWSSB official said that due to the sudden gush of water, the turbidity of the raw water increased due to which the treatment plants at TK Halli was not able to treat the required quantity of water.

The turbidity in water mainly affected the water supply of Cauvery IV stage II phase, which is the latest stage of water supply commissioned by the Board in October 2012.

Many areas in the city were also affected by the partial supply of water.

BWSSB’s engineers along with many other workers worked continuously for two days to clean the filter beds and the nozzles, which had a huge amount of sludge due high turbidity in raw water.

Explaining the process of cleaning, one of the officials said due to the high amount of soil in the water, the filter beds were chocking and the sludge on the nozzles of the dissolved air flotation (DAF) had to be continuously cleaned.

The Nozzles on DAF was cleaned once every eight hours which otherwise was cleaned once in two days.

The engineer said due to high turbidity, there was a short supply of about 100 MLD. However, the total supply of 1,400 MLD has been restored, he added.