Question- A circular primary clarifier processes an average flow of 3000 m³/d of municipal wastewater. The overflow rate is 25 m³/d. Find the diameter of clarifier.

A municipal wastewater treatment plant processes an average of 14,000 m3 / day. The peak flow is 1.75 times the average. The wastewater contains 190mg/L BOD and 210 mg/L suspended solids at an average flow and 225 mg/L BOD and 365 mg/L suspended solids at peak flow. Determine the following for a primary clarifier with a 20-m diameter.  Assume eff. BOD of 20 mg/L and effluent TSS of 30mg/L for average and peak flows.    1. Surface overflow rate and the approximate removal efficiency for BOD 5 and suspended solids @ average flow.  2. Surface overflow rate and the approximate removal efficiency for BOD 5 and suspended solids @ peak flow.  3. Mass of solids (kg/day) that is removed as sludge from average and peak flow conditions.

Determine the size (diameter and depth) of the secondary clarifier (s) in a municipal activated sludge treatment facility: The wastewater characteristics are: Population 250,000, Average per-capita flow rate = 380 1/capita-day and Peak factor = 2.2. The suspended solids concentration is assumed to be 2500 mg/L. The over flow rate is 110 and 60 m3/d-m2 for peak flow and average flow respectively and solids loading at average flow is 110 kg/d-m2. Estimate detention time if the depth is 4.5 m. What would be the weir loading? Also answer the following questions. (hint : you should use all 3 loading criteria) a. How many kilograms of solids are loaded onto each clarifier per day? b. If the removal efficiency is 65% then how many kilograms of solids are removed from the total flow per day? C. What is the concentration of solids in the wastewater leaving the clarifier? Determine the size (diameter and depth) of the secondary clarifier (s) at a municipal activated sludge treatment facility:…

4.4.If an industrial plant is generating wastewater containing 350 mg/L of lysine [HO₂ CCH (NH2) (CH2)4 NH2], the C-ThOD required is around: a) 538 mg 02/L b) 759 mg 02/L c) 642 mg 02/L d) 862 mg O₂/L 4.5.A circular clarifier has a diameter of 60 ft. If the primary effluent flow is 2 MGD, what is the surface overflow rate in gpd/ft²? a) 1080 gpd/ft² b) 708 gpd/ft² c) 845 gpd/ft² d) 777 gpd/ft² 4.6.A stream with a velocity of 0.5 m/s, de-oxygenating rate of 0.2/day, and re-oxygenation rate of 0.3/day. The ultimate BOD in the discharge point is 30 mg/L. The stream is in a saturation level before outfall with a temperature of 20°C. Assume same temperature, what is the DO in 5 km d) 12.3 mg/L downstream? a) 8.4 mg/L b) 9.1 mg/L c) 10.2 mg/L