Effluent Treatment Plant – ETP

The screened sewage will then be collected in an Equalization Tank in order to dampen the variation in flow rate and pollutant concentration. Mixing in the Equalization Tank will be provided by coarse bubble diffused aeration. From the Equalization Tank, the equalized sewage will be pumped via feed pumps into Aerobic biological reactors (Aeration Tanks).

The Aeration Tank MLSS considered for design is 3500 – 4,000 mg/l. Air will be provided by fine bubble diffused aeration. Compressed air will be provided by the Air Blowers. WTPL proposes an extended aeration process. The aeration tank will have a low F/M ratio (0.1 kg BOD / kg MLSS-day) and a high Solids Retention Time. This will encourage endogenous respiration and reduce the sludge yield as well as increase the process stability.

Mixed liquor from each Aeration Tank will flow by gravity into the Lamella Clarifier Tank where the mixed liquor suspended solids (MLSS) will be settled. Settled sludge from the bottom of the Lamella Clarifier will be recycled back to Aeration Tank in order to maintain the desired MLSS and excess sludge will be wasted to aerobic sludge digester cum thickener. The Scum from the top of Lamella Clarifier is also fed to excess sludge wasting line.