A city has a population of 100000 with an average rate of demand of 160 litres per head per day. What is the actual number of filters required if the size of each filter is 9 m x 5m? Assume the average filtration rate as 4500 litres per hour per m². (a) 1 (c) 4 (b) 2 (d) 5

5. You are asked to design a single media filtration system for a drinking water facility. The design flow rate is 20 mgd (million gallons per day). The ideal filter velocity for your system is 8 m/hr. You design a set of filters to be used in parallel. Each filter box has a surface area of 50 m². a. How many filters do you need to construct? b. Estimate the (clean-filter) head loss in kPa? c. What mass removal (filter efficiency) would you expect for an influent stream that contains equal parts (by mass) of 1, 10 and 100 um particles? You can assume an adhesion efficiency a = 0.7. Sand Effective Size (mm) 0.8 Uniformity Coefficient 1.2 Grain Porosity Density (g/cm³) 2.6 0.4 Layer Thickness (m) 1.5

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.

In a BOD test, 5 ml of wastewater (with no dissolved oxygen) is diluted with 295 ml of water containing 8.5 mg/1 of dissolved oxygen. After 5 days incubation at 25°C, the dissolved oxygen content of the mixture is 5 mg/1. Temperature coefficient can be taken as 1.047 and BOD rate constant is 0.23 per day (base e) at 20°C. The ultimate biochemical oxygen demand of the wastewater is