Bengaluru apartment STPs: sludge dewatering guide
A practical guide for apartment and tech-park STP operators in Bengaluru on handling excess sludge, choosing a polymer and keeping treated water fit for reuse.
Why apartments run their own STPs
Large residential complexes and commercial buildings in Bengaluru are required to treat their own sewage and reuse the treated water for flushing and gardening. The Karnataka State Pollution Control Board sets the conditions, and the treated water quality is checked.
Where the sludge comes from
Most of these plants are extended aeration, SBR or MBBR units. Bacteria grow as they treat the sewage, and the extra biomass has to be removed regularly as excess sludge. Left in the plant, it rises in the clarifier and spoils the treated water.
Dewatering options in small plants
Smaller STPs use sludge drying beds, bag filters or a small filter press; larger campuses use a screw press or centrifuge. All of them work better when the sludge is conditioned first with a cationic polymer, which turns thin sludge into a firm, easy-to-handle cake.
Choosing and buying the grade
Cationic MQ in 10 kg bags suits most apartment plants, since a bag lasts weeks at small doses and stays inside the shelf life. Larger tech parks with daily pressing may prefer Cationic HQ in 25 kg bags.
Day-to-day tips
Make up a fresh solution every day or two, mix it gently for 45 to 60 minutes before use, and add it where the sludge is gently stirred. If the cake turns sticky or the filtrate looks slimy, the dose is probably too high.
Coloured water from garment units
Denim and garment laundries in Peenya and the outer estates face a different problem: colour. They use SunDec SC05 first and then a cationic flocculant, which is covered in our guide to removing colour from textile effluent.
Not sure which grade suits your water?
Send us a one-litre sample or describe your process. We test it in our lab free of charge and recommend a grade and starting dose, and quote within 1 business hour.