1- The influent suspended solids concentration to a primary settling tank is 435mg/L. The average flow rate is 0.050m3/s. If the suspended solids removal efficiency is 60 percent, how many kilograms of suspended solids are removed in the primary settling tank each day?
2- The town of Camp Verde has been directed to upgrade its primary WWTP to a secondary plant that can meet an effluent standard of 25 mg/L BOD5 and 30 mg/L of suspended solids. They have selected a completely mixed activated sludge system for the upgrade. The existing primary treatment plant has a flowrate of 0.029m3/s. The effluent from the primary tank has a BOD5 of 240mg/L. Using the following assumptions, estimate the required volume of the aeration tank:
(a). BOD5 of the effluent suspended solids is 70 percent of the allowable suspended solids concentration.
(b). Growth constants values are estimated to be: Ks = 100mg/L BOD5; kd= 0.025 d-1; µm=10d-1; Y= 0.8 mg VSS/mg BOD5 removed.
(c). The design MLVSS is 3000mg/L.
3- The 500- bed Lotta Hart Hospital has a small activated sludge plant to treat its wastewater. The average daily hospital discharge is 1500 L per day per bed, and the average soluble BOD5 after primary settling is 500 mg/L. The aeration tank has effective liquid dimensions of 10m wide by 10m long by 4.5m deep. The plant operating parameters areas follows:
MLVSS =2500mg/L
MLSS= 1.20 (MLVSS)
Determine the following: aeration period, F/M ratio, SVI, solids concentration in return sludge.