STP Treatment Procedure
Once the sewage water entering into intake tank, grits are removed through grit removal section, the effluent then passes through Fine screen and classifier to remove other waste as well as cut it into small pieces and separate out through classifier.
The organic residues return to primary clarifier through organic return pump via partial Flume which is equipped with ultrasonic flow meter.
The sewage from primary clarifier distribution chamber flows by gravity to primary clarifier. Primary sludge generated daily are transferred Gravity Sludge Thickeners. The thickened sludge is then transferred to 2 nos of Anaerobic Digesters, where compressed air blowing mechanisms for digestion is provided. During digestion Methane gas is generated, will transfered to Gas Holders, which in turn converted into Bio-CNG. This Bio-GNG Gas is then made available to NMC for further use.
The digested sludge is then transferred to Centrifuge mechanism for dewatering of sludge and the cake formed is then dumped to NMC Dumping Yard. The leachate from centrifuge collected in centrate tank, from where shifted to partial flumes
The overflow of primary clarifier passes biological treatment section comprising Sequential Batch Process (C - Tech) Basin. 8 nos of inbuilt basins are operating for designed flow of 130 MLD. FeCl3 dosing (14 ppm) is added in each basis to control the phosphorous level in the basin.
Four hour cycle per basin is designed by C-Tech solutions, wherein 1st two hours are for fill aeration, where overflow from primary clarifier comes inside and simultaneously aeration by means of air blower continued inside the basin. The sludge inside the basin settled down in third hour due to stoppage of air from air blower. At the start of forth hour, decanter comes down the basin and start decanting. Near about 2.7 MLD sewage water decanted per hour in each basin and goes to CCT for chlorination.
As per design 8 ppm chlorine solution doses in CCT, to maintain the Residual Chlorine of TTP more than 1 ppm.
The Secondary treated sewage water passes through anthracite filters which are equipped by Pebbles, Gravels of different sizes, SQS & Activated Charcoal. Total 12 nos of Filters are constructed at plant. The overflow of these filters (TTP) pumped to KTPS Power plant (3 x 660 MW).
It is necessary to backwash these filters at regular intervals. There is an overhead tank constructed above the TTP to avail backwash water facilities. When TTP water pumped to TPS, Koradi, one tapping is provided to fill this overhead tank.
After backwashing, the contaminated water generated is transferred to Backwash Recovery Sump. From there shifted to Clariflocculator to remove the sludge by means of Ferric Alum. The overflow of Clariflocculator passes to CCT for chlorination again. The excess sludge generated is transferred to BRS Thickener. The thickened sludge shifted to centrifuge Via Centrifuge Sump. The overflow of BRS Thickener collected at centrate tank and after that pumped to Partial Flumes.
Safe Management of chlorine gas
We are using Chlorine gas in tertiary treatment of sewage for disinfection and improve the clarity of treated effluent. Chlorine gas leakage detection system is provided and for handling any major or minor chlorine gas leakage, caustic scrubbing system is provided.