STP (Sewage Treatment Plants)

About STP (Sewage Treatment Plants)

A Sewage Treatment Plant treats domestic wastewater — from toilets, kitchens, bathrooms and laundry — so it can be safely discharged or, more usefully, reused for gardening, flushing, cooling towers and road washing. STPs are now mandatory for most housing societies, hotels, hospitals, schools, malls and commercial buildings under state pollution-board rules. We design and build STPs for societies, institutions and commercial projects.

How an STP works

Sewage first passes a bar screen to catch solids and cloth, then an oil and grease trap for kitchen waste. The equalisation tank balances the huge morning and evening peaks so downstream units see steady flow. In the aeration tank, air blowers feed oxygen to bacteria that break down organic matter — this is the heart of the plant. Water then enters a settling tank / clarifier where sludge separates, followed by filtration and chlorination or UV disinfection to make the treated water safe for reuse.

MBBR, SBR or conventional?

MBBR (moving bed bio-reactor) uses floating plastic media that hold a large bacterial population in a small tank — ideal where space is tight, which is why most society STPs use it. SBR works in timed batches in a single tank and gives very good, consistent output quality. Conventional activated sludge needs more space but is simple and proven. The right choice depends on available land, budget, output norms and how much operator attention the plant will realistically get.

Sizing and daily operation

Size an STP on KLD (kilolitres per day) — normally 120-135 litres per person per day for residential buildings, adjusted for occupancy. Undersizing to save cost is a false economy: an overloaded STP smells, fails tests and invites notices. Day to day, keep the blowers running as designed, check DO and MLSS, remove excess sludge, and never let the aeration stop for long — the bacteria die and recovery takes weeks.

What we supply

Complete STP design, fabrication, installation and commissioning, MBBR media, air blowers and diffusers, pumps, filters, UV and chlorination systems, and online instruments. Standard warranty 1 year, AMC and operator training available (charged separately), service across Delhi NCR and pan-India, with GST invoice on every supply.