Kolkata leather and engineering effluent
How Kolkata's tanneries at Bantala, Howrah's foundries and the Hooghly water works treat their water, from protein-rich effluent to monsoon turbidity.
The leather complex
Kolkata's tanneries were moved to a dedicated leather complex at Bantala, where a common effluent plant treats their combined discharge. Tannery effluent carries salt, lime, sulphide, protein, fat and chromium.
Treating tannery effluent
Chrome-bearing liquors are best segregated for recovery. The combined effluent is equalised, coagulated and clarified with a cationic grade such as Sunfloc Cationic HQ, which gathers protein and fat into heavy flocs. Tannery sludge is bulky, and the same polymer helps the press release water.
Foundries and engineering in Howrah
Howrah's foundries and workshops reuse water for sand washing, quenching and machining. An anionic grade such as Sunfloc Anionic HQ at the settling-pit inlet clears fine sand and scale quickly.
Jute mills
Jute processing uses water for softening and batching, producing effluent with fibre and oils. Settling with polymer before discharge removes much of the suspended load.
Hooghly water and the monsoon
River water turbidity rises sharply in the monsoon. Water works should jar-test daily in the rains and raise the anionic dose in steps as turbidity climbs.
Regulation and supply
Units are regulated by the West Bengal Pollution Control Board. Road freight from Chennai usually takes four to five days.
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