Key Questions
What is a sewage treatment plant and why do buildings need one?
A sewage treatment plant (STP) treats domestic wastewater on site so it can be safely reused. Hotels, IT parks and residential complexes need one under state building bye-laws, and about 70% of treated STP water can be reused for flushing and irrigation, reducing freshwater bills.
Most Indian states, including Maharashtra, require on-site STPs for buildings above a certain area, and Occupancy Certificates are withheld until the STP is commissioned and test reports are submitted. That makes the STP a critical-path item for any development. The practical challenge is that conventional STPs are noisy, odorous and space-hungry. Navbharat Water builds MBR-based STPs from 10 KLD to 2 MLD that are designed to disappear into the building: installed below ground, enclosed with odour control, and kept under 55 dBA at 3 metres. Treated water is disinfected by chlorination and reused for toilet flushing, cooling tower makeup, vehicle washing and landscape irrigation, with dual-plumbing drawings supplied for the MEP team. Navbharat Water also provides the commissioning reports, test certificates and SPCB consent application support needed so the STP does not delay the project at the final hurdle.
MBR vs SBR: which STP technology is better?
MBR is better where space and reuse quality matter. It needs no secondary clarifier, so its footprint is 30–40% smaller than an equivalent SBR, and it consistently delivers outlet BOD below 10 mg/L, against the BOD of 30 mg/L that SBR typically achieves.
A Membrane Bioreactor combines activated sludge with submerged hollow-fibre ultrafiltration membranes with a pore size of 0.04 micron in one compact tank. The membranes replace the clarifier, which is why a 100 KLD MBR STP needs roughly 60–80 m² of plant room, compared with 120–150 m² for an equivalent SBR system. Outlet TSS is 10 mg/L or less and faecal coliform stays below 100 MPN/100 mL, meeting BIS flushing water quality. SBR still has a place. Its fill-aerate-settle-decant cycles in a single tank make it a proven, economical workhorse with good nitrogen and phosphorus removal for townships and institutional campuses. MBBR suits sites with variable hydraulic or organic loads, and the conventional activated sludge process suits large plots where footprint is not constrained. Navbharat Water engineers all four technologies and selects the one that fits the site, budget and reuse target.
How much space and maintenance does a building STP need?
A 100 KLD MBR STP needs approximately 60–80 m² of plant room space, including tanks, membrane unit and control panel. Maintenance involves monthly membrane backwash and integrity testing, quarterly chemical cleaning and sensor calibration, which Navbharat Water covers under an Annual Maintenance Contract.
Because MBR tanks are GRP or stainless steel with sealed lids and an enclosed odour-control system, the plant can sit in a basement or semi-underground room without smells migrating to adjacent spaces, and acoustic enclosures keep noise below 55 dBA. Navbharat Water supplies AutoCAD drawings so the architect can coordinate the plant room early. After commissioning, the Annual Maintenance Contract also covers sludge disposal coordination, with emergency response within 24 hours across the service network in Maharashtra, Gujarat, Karnataka and Tamil Nadu. The results hold up over time. At a 100 KLD MBR STP in the basement plant room of a five-star hotel in Mumbai, outlet BOD has stayed consistently below 8 mg/L, and 65 KLD is recycled daily to toilet flushing and pool makeup, saving ₹22 lakh a year in MCGM water charges. The hotel operations team has reported zero odour complaints in three years of operation.
