Municipal wastewater treatment using novel constructed soil filter system

The study gives a new approach for contaminant removal from municipal wastewater using constructed soil filter (CSF) and presents performance of two CSF units located in Mumbai, India. In this system, natural weathered rock is formulated which combines sedimentation, infiltration and biochemical processes to remove suspended solids and oxidisable organics and inorganics of the wastewater. Results show elevated dissolved oxygen (DO) levels, removal of COD (136–205 to 38–40 mg l−1) and BOD (80–125 to less than 12 mg l−1) suspended solids from 135–203 to 13–18 mg l−1 and turbidity from 84–124 to 8–11 NTU, bacterial removal of 2.4–3.1 log order for Total coliform and Fecal coliform from site I which is almost 8 years old facility, and site II which is 3 years old. Estimated hydraulic retention time of 0.5–1.0 h, hydraulic loading of 0.036–0.047 m3 m−2 h−1, no pretreatment, high DO levels in the effluent, no bio-sludge production, no mechanical aeration, low energy requirement (0.04 kW h m−3) and green aesthetic ambience are its unique features.