Answer Happy

1. For a municipal WWTP with an average daily flow of 2.0 MGD and a peak flow of 6.0 MGD, design a rectangular primary clarifier based on the following criteria: BODs concentration entering the primary clarifier 180 mg/L Assume minimal removal of BODs in the primary clarifier Use minimum depth (8 ft) criteria for a primary clarifier Multiple units capable of independent operation shall be provided in all facilities where design flows exceed 250,000 gpd. SOR = 1000 gpd/ft? (normal conditions) SOR = 2500 gpd/ft? (peak conditions) Weir loading rate = 20,000 gpd/ft Maximum HRT = 2.5 hours What percent removals under normal conditions would you expect from your design based on the graph on page 346 of your textbook?
2. A municipal WWTP receives an average daily flow of 10.0 MGD. Two (2) circular clarifiers working in parallel will treat the entire flow. The peak hourly flow anticipated is 2.5 times the average daily flow. Use the design criteria from Tables 7.9 and 7.10 in the textbook on page 347. Note any assumptions you made to complete your design Determine: Dimensions of the clarifiers The detention time in the clarifier The weir overflow rate (gpd/ft) at average and peak hourly flow rates The BOD and suspended solids removal efficiencies at the average daily flow rate