What is the purpose of secondary wastewater treatment? a. To reduce toxic chemicals and heavy metals. b. To remove sediment and silt. c. To kill disease-causing agents. d. To reduce the water’s biochemical oxygen demand

A flowing stream has a temperature of 14°C, flow rate of 3.0 m}sec, saturated dissolved oxygen content and BODs of 15 mg/L with reaction rate constant of 0.13/day. Waste is discharged into the stream at a flow rate 0.5 m3/sec, temperature of 30°C, ultimate BOD of 50 mg/L and dissolved oxygen content of 2.5 mg/L. The discharged waste has same characteristics as the initial pollutant in the stream with the same reaction rate constant of 0.13/day.Determine:1. Temperature of the resulting combine flow at the mixing point2. Ultimate BOD of the combine flow at the mixing point. 3. Dissolved oxygen content in the combine flow at the mixing point. 4. Oxygen deficit in the resulting combine flow at the mixing point.5. Oxygen deficit and dissolved oxygen content in the stream at exactly one day after the initial mixing of the waste into in the stream if the deoxygenationand reaeration rate constants are 0.2/day and 0.4/day, respectively.6. Length of time in days to reach minimum oxygen content,…

An activated sludge tank is 30 m long and 10 m wide and has an SWD of 4 m. The wastewater flow is 4.0 ML/day and Compute: a) the BOD concentration which will be applied to the aeration tank b) the food-to-microorganism ratio for the system. O a) 105 mg/L b) F/M=0.35 O a) 195 mg/L b) F/M=0.65 O a) 105 mg/L b) F/M=0.22 O a) 195 mg/L b) F/M=0.35 the raw 5-day BOD is 300 mg/L. Assuming that 35 percent of the raw BOD is removed in the primary clarifier, and the MLSS concentration is 1000 mg/L.

A flowing stream has a temperature of 14°C, flow rate of 3.0 m}sec, saturated dissolved oxygen content and BODs of 15 mg/L with reaction rate constant of 0.13/day. Waste is discharged into the stream at a flow rate 0.5 m3/sec, temperature of 30°C, ultimate BOD of 50 mg/L and dissolved oxygen content of 2.5 mg/L. The discharged waste has same characteristics as the initial pollutant in the stream with the same reaction rate constant of 0.13/day.Determine: 4. Oxygen deficit in the resulting combine flow at the mixing point.5. Oxygen deficit and dissolved oxygen content in the stream at exactly one day after the initial mixing of the waste into in the stream if the deoxygenationand reaeration rate constants are 0.2/day and 0.4/day, respectively.6. Length of time in days to reach minimum oxygen content, in the stream at the same rate constants given in part e above. 7. The maximum oxygen deficit in the stream at the same rate constants given in part e above. 8. The minimum dissolved oxygen…