Design Evaluation of Biological Unit as a Basic Consideration to Determine the Design Criteria of Domestic Wastewater Treatment Plant at 1^st Zone, Jakarta

The evaluation of existing Wastewater Treatment Plant (WWTP) is doing by evaluate the performance and design of biological unit. On design planning of WWTP, the biological process unit is the key role to reach the target of pollutant removal efficiency. The optimum design parameter of biological process unit could be attained from the real condition by doing evaluation of existing WWTP as a comparison. The selection of an appropriate existing WWTP is based on the similarity of region characteristic, typical activities of people who use the water and wastewater quality and characteristic, and it match to Tana Tinggi WWTP. Tana Tinggi WWTP has capacity 63.8 L/s that already serve 2785 home connections system or 77% of serving area of Tangerang City. The process and operation units are consist of screening, activated sludge, clarifier and sludge handling system. The evaluation of activated sludge gives the data that BOD loading rate is 0.32 Kg/m³.day, MLSS is 3920 mg/L, F/M ratio is 0.036 kg BOD/kg MLSS.day, hydraulic retention time (HRT) is 6.78 hours and sludge age is 5.16 days. From the evaluation results there are three parameters that can be determine as design criteria and will be apply for design of biological process unit. The parameters are MLSS 3900 mg/L, HRT 6 hours and sludge age 5 days. In otherwise, the F/M ratio doesn't prove the appropriate value and it show that the activated sludge of existing WWTP is leak of nutrition that is necessary for microorganism metabolism. (paper)