CIVE 450 Problems Page 2, Spring 2014

8. Two rectangular clarifiers, each 10 m long, 3.7 m wide and 2.5 tneters d 2270 m’*/d following alum i total weir coagulation. The effluent channels ha’ length of 12 m. calculate the detention time, horizontal velocity pre and rate of flow over the weir. Com the calculated val i ; i saline pare cu values with those in table provided 9. A water treatment plant has four clarifiers treating 0.175 m3/sec of water. Each clarifier is 4.88 m wide, 24.4 m long, and 4.57 m deep. Determine: (a) the detention time, (b) overflow rate, (c) horizontal velocity, and (d) weir loading rate assuming the weir length is 2.5 times the basin width. 10.A settling column analysis of a suspension is run. The initial solids concentration is 250 mg/L. The resulting efficiency matrix is shown in table below. What will be the overall removal efficiency of a settling basin which is 3m deep with a detention time of 1 hr and 45 min. What surface overflow rate should be used in a full sized clarifier in order to achieve equivalent results? DRAW A LARGE GRAPH Time of Sampling, Min. Depth ------------------------------- m 30 60 90 120 150 180 12 28° 42::51 30- 10 25 38 47 5462 ay NE, OF * Results of suspended solids removal efficiency 11. The data shown in the following table was obtained from a settling column analysis. Find the detention time for a tank of 2.4 m effective depth to remove of the suspended particles. Time, min 45 60 90 120 75 80 84 85 69 jie) $1 84 65 70 79 82 63 68 76 81 you have to introduce a safety factor equivalent to 2.