Chemical Treatment Process.

Screen Chamber: At first the raw effluent come from the process section  through the screen chamber to equalization tank. The suspended coarse solids are separate from waste water by the bar screen.

Equalization Tank: The equalization tank is equipped with three ejectors due to homogenizing the waste and to prevent settling of solids.

Flash Tank: The effluent from the equalization tank is transferred into the flash mixer tank. Here Lime, Alum and Polymer are added according to the proper requirement of sedimentation of sludge. Normally 0.70-0.80 gm/L Alum, 0.4-0.6 gm/L Lime and 0.8-1.0mg/L Bulab 5651 is added. This ration can be changed depending on characteristics of Effluent. An agitator is installed in flash mixer to properly mixing the chemical with effluent.

Clariflocculator:  The effluent from the flash mixer then transfer to the clariflocculator (Primary clarifier) for settling of the solids. Chemical reactions are occurred here. Inorganic substances (Chromium) are precipitated here. The settling solids are then transferred to the sludge thickener.

Aeration Tank: The overflow of the clariflocculator is then transferred to aeration tank (Aeration Tank-I & Aeration Tank-II) for biological treatment. The target of biological treatment is to convert soluble organic matter and non soluble colloidal solids into inert solids, other simple end products (CO, H₂O, NH₃ etc), new cells and energy by oxidation or synthesized by micro organisms in aerobic condition. For the nutrition of micro organism nutrients such Urea and DAP are added. The micro organism also required oxygen to sustain the microbial activity. Oxygen is added by fixed aerator.

Secondary Clarifier: After biological treatment the over flow from the aeration tank is transferred to secondary clarifier. The biological mass is then separated and settled at the  lower part of the clarifier. We recycle it in aeration tank. If the bio mass is above 25% we transfer it to the sludge thickener.

Buffled Channel: The overflow from the secondary clarifier is then transferred into tube settler through a baffled channel. If the parameter of the water is not comply to our requirement we add small amount of Lime, Alum and Polymer again.

Tube Settler: The tube settler is equipped with full of tubes which are 60° angle to the wall. In tube settler the remain sludge is settled. The overflow from the tube settler is collected in collection sump-I and sludge is transferred to the sludge thickener.

Pressure Sand Filter: The treated water is pumped through a pressure sand filter to remove any fine solids that might have been carried over the water. The water from the pressure sand is collected in collection sump-II.

Activated Carbon Filter: The water of collection sump-II is slightly colored. To remove this color we transfer it through the activated carbon filter.

After all the process we check the parameters of the treated water. If it comply with our specification we discharge it into inland water. Otherwise we recycle it into equalization tank to treat again.

Sludge Drying Beds: For drying of sludge we transfer it from sludge thickener to sludge drying beds. When the sludge dry we take it for land filling in our factory in safe way.

Centrifuge: In the rainy season it is not possible to dry the sludge in beds, then we use centrifuge to make the cake of sludge.