The process effluent is fed to the first stage aeration tank where cooling water blow down is also introduced to dilute the same. Sewage is screened in a screen chamber, and then pumped to the first stage aeration tank through a grit chamber. First stage aeration tank is equipped with four surface aerations (15 HP each), and would thus reduce BOD substantially. The mixed liquor from first stage aeration tank flows by gravity to intermediate clarifier to settle bacterial solids. The settled sludge is pumped back to the first stage aeration tank whereas effluent flows by gravity second stage aeration tank, which is also equipped with surface aerator (7.5 HP). The residual BOD would be removed in the second stage aeration tank. Effluent from the second stage aerator flows to final clarifier where solids are settled. A small quantity of acid and alum is continuously added here to adjust pH & TSS within specification. Excess sludge in case of both the clarifiers is sent to sludge drying beds.