1. Determine the 5-day 20°C BOD of a wastewater if the 3-day 10°C BOD is 100 mg/L. Assume a first-order model is valid, k equals 0.2/day, and the temperature coefficient is 1.135.

There is sedimentation tank that is used to remove suspended solid particles from an incoming wastewater stream. The incoming wastewater has a flowrate of 150 m³/hr and the sedimentation tank has a basin surface area of 15 m2. Assume the operation temperature is 25 C and assume that sedimentation is the only process by which suspended solid particle are removed from the sedimentation tank. a) What is the settling velocity of the suspended solids in this sedimentation tank in the unit of m/s

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A BOD test is to be run on a sample of wastewater that has a five-day BOD of 195 mg/L. If the initial DO of a mix of distilled water and wastewater is 9.0 mg/L, and the test requires a decrease in DO of at least 2.0 mg/L with at least 2.0 mg/L remaining at the end of the five days, what range of dilution factors (P) would produce acceptable results? In 300-mL bottles, what range of wastewater volumes could be used?

Use Thoma's method. Kindly give me right solution with step by step clearly.

A 4-mL wastewater sample is mixed with 16-mL of distilled water for dilution. Calculate the Dilution Factor (DF) for the sample. DF= A/

10. A 15,000 ft³ conventional activated sludge system has a recycle ratio of 0.38, an influent flow rate of 17,000 ft°/day, a mixed liquor volatile suspended solids (MLVSS) concentration of 280 mg/L, and an influent BOD, of 60 mg/L. What is most nearly the recycle rate of the system? (A) 2800 ft/day (B) 3600 ft/day (C) 5300 ft/day (D) 6500 ft°/day А. В. O000

Then, you were asked to find out the biodegradability of this wastewater by conducting a 5-day biochemical oxygen demand (BOD5). A good indication for a biodegradable wastewater would have a COD/BOD ratio of 2 and above. Here, 55 mL of sample was employed for the test where the measured dissolved of oxygen at day 0 was 7.7 mg/L and 2.3 mg/L, respectively. Assess if the wastewater is biodegradable.

T Settled sludge and filter wash water from water treatment are thickened in Problems 703 clarifier-thickeners prior to mechanical dewatering. The settled sludge volume is 1150 gpd with 1.0% solids, and the backwash is 9800 gpd containing 500 mg/l of suspended solids. Calculate the daily quantity of thickened sludge, assuming a concentration of 3.0% solids

A factory with a wastewater flow of 0.011 m³/s and a BOD; of 590 mg/L discharges into a small stream. The stream has a minimum dry season flow of 1.7 m/s. Upstream of the factory, the BOD; of the stream is 0.6 mg/L. The BOD rate constants ka at 20 °C are 0.115 di for the factory wastewater and 3.7 di for the stream. The temperature of both the stream and the factory wastewater is 20 °C. After mixing, the D0 was 6.3 mg/L, the velocity was 0.1 m/s, the mean depth was 2.5 m and the decay constant, ka , was 0.75 d. a. Calculate the initial ultimate BOD after mixing (HINT: First find Lo in each flow] b. Determine the time when the critical DO occur: c. Where does the critical DO occur?' d. Determine whether any fish migration will occur if they require a DO level of at least 3 mg/L in their habitat.