choose the corect answer and give detail explaniation justify your selection

Which coagulant is widely used for sewage treatment? 1. Lime 2. Alum 3. Ferric chloride 4. Ferric sulphate vii- For a given discharge, the efficiency of sedimentation tank can be increased by. 1. Increasing the depth of the tank 2. Increasing the surface area of the tank 3. Decreasing the depth of the tank 4. Decreasing the surface area of the tank The coarse screen is normally kept inclined at about 4560 to the horizontal, so as to: 1. Decrease the opening area to reduce the flow velocity 2. Decrease the opening area to increase the flow velocity 3. Increase the opening area to reduce the flow velocity 4. Increase the opening area to increase the flow velocity A water treatment plant of capacity, 1m3/s has filter boxes of dimensions 6 m10m. The loading rate to the filters is 120m3/ day /m2. When two of the filters are out of service for back washing, the loading rate (in m3/ day /m2 ) is 1. 144 2. 122 3. 133 4. 124 x A village has a population of 200 with an average rate of water demand of 100 litres per capita per day. A rapid sand filter having an average filtration rate of 100 liter/hour /m2 is to be designed for water treatment. The area of rapid sand filter required is: (Take the ratio of maximum demand to average demand as 1.5) 1. 14.50m2 2. 8.00m2 3. 12.50m2 4. 10.00m2 In waste pollution prevention hierarchy, arrange following from least preferred to most preferred. A. Waste Concentration B. Waste Separation C. Waste treatment D. Recycling or Reuse E. Landfill Choose the correct answer from the options given below 1. E, A, C, B, D 2. E, C, A, B, D 3. E,C,B,A,D 4. E,C,A,D,B Activated sludge process is an example of: 1. Anaerobic suspended growth process 2. Anaerobic attached growth process 3. Aerobic attached growth process 4. Aerobic suspended growth process