2.20     SPECIFICATION OF EFFLUENT TREATMENT UNITS ; (3500 TCD PLANT)

The specification of the ETP is presented below

i.        MAIN GUTTER FOR COMBINED EFFLUENT


The main gutter is constructed with stone or brick masonry covered with 75mm thick RCC slabs/stone slabs

ii      SCREEN

Coarse screen of 25mm gap followed by the screen of 10 mm gap is provided in main gutter. Velocity through screen is 0.3 m/s at average flow and 0.6 m/s at peak load. Head loss through screen at maximum flow is 0.15m. The floatings entrapped on the screen are removed manually:

The bar screen are fabricated with 6mmx25mm flats. The flats are suitably supported on 10mm x 10mm   cross bars. The bar screen is located at 30° inclination to the flow direction.

Screen size : 0.6 x 0.8
Screen chamber size : 0.6 x 1.2m x 0.55m

iii. Grit Chamber

Two Grit chambers are provided for handling twice the average flow at peak iosld. Each  chamber has two stutter gates and designed independently operate/ The overall size of this twin grit chamber is 6m long 1.2 m width and11 mdepth. Grit' chamber is designed to provide an effluent velocity of 0.2 m/sec and retention period of 5 mins.

iv. Oil Separator ( Oil and Grease Trap)

An oil separator tank of sufficient size is provided close to the grit chamber floating scum consisting of grease, fiber matter is periodically skimmed off.