Greenfield STP and rainwater harvesting handover at a 600-bed hospital

A 600-bed multi-speciality hospital under construction in Gujarat engaged Terraquaer during the detailed engineering phase to design, supply, install and commission the sewage treatment plant, rainwater harvesting system, and firefighting infrastructure - with the contractual requirement that all statutory clearances be in place at the handover date. The hospital's sewage generation was estimated at 360 KLD at full occupancy, with a treated-water reuse target covering 100% of flushing demand (estimated at 90 KLD) and 100% of landscaping irrigation (estimated at 30 KLD), reducing the campus's freshwater draw by approximately 120 KLD.

STP design: MBBR train for reuse-grade output

Technology selection favoured Moving Bed Bio-Reactor (MBBR) over MBR for this application. The hospital's sewage load profile - high during the day shift and variable through the night - favoured MBBR's inherent load tolerance, and the reuse targets (flushing and landscaping, not cooling tower or HVAC make-up) did not require MBR-grade permeate. The MBBR was configured as a two-stage system: Stage 1 for BOD removal and nitrification, followed by Stage 2 for partial denitrification, then a tube-settler clarifier, dual-media pressure filter, and UV disinfection to meet Gujarat state board reuse norms (BOD < 10 mg/L, TSS < 10 mg/L, faecal coliform nil). K5 carrier media was specified at 67% fill ratio in both stages, giving a total protected surface area of approximately 2,800 sq.m across the two reactors. Sludge dewatering used a screw press rated at 1.5 cu.m/hr, with dewatered cake disposed through the hospital's biomedical waste vendor under MoEF&CC guidelines.

Rainwater harvesting, firefighting, and statutory clearances

The rainwater harvesting system was designed for the 2.8-acre campus. Roof-catchment area of 4,200 sq.m was connected through first-flush diverters to a 75,000-litre collection sump, with overflow to three percolation wells of 3-metre diameter and 12-metre depth. Estimated annual recharge volume is 3.2 million litres. The firefighting scope covered hydrant ring main, wet riser design for the 8-storey tower, pump room (main electric pump 750 LPM at 7.0 kg/sq.cm, diesel standby pump, jockey pump), fire extinguisher locations, and smoke-detection tie-ins.

Terraquaer coordinated the Fire NOC application from the pre-design stage, incorporating inspection comments into the final layout before construction - avoiding the sequence where the system is built, inspected, and then modified. The CTE was cleared by the state board prior to construction start. The CTO inspection was timed with the plant's Performance Guarantee test - 72-hour continuous operation at 80% design load - witnessed by the board's authorised officer. Treated-water quality during the PG test: BOD 6.8 mg/L, TSS 7.2 mg/L, faecal coliform absent. CTO was issued without conditions on the handover date. The hospital operates with a combined freshwater saving of 110-120 KLD depending on season, against a project cost 12% below the original budget estimate.