- A A Circular Sedimentation Basin With A Depth Of 4 M With A Freeboard Of 0 5 M And A Diameter Of 10 M Diameter Of I 1 (151.65 KiB) Viewed 24 times
(a) A circular sedimentation basin with a depth of 4 m (with a freeboard of 0.5 m) and a diameter of 10 m (diameter of its center feed is 1 m) is proposed by a consultant for treating a surface water with a flowrate of 5,000 m®/d. The surface water has a particle concentration ranging from 100-150 mg/L throughout a year. After going through coagulation, flocculation and sedimentation processes, the particle concentration in the effluent is claimed to be below 50 mg/L. The results obtained from a column test conducted for the flocculated floc are summarized in the following table. [19 marks] Particle removal efficiency (%) obtained in the column test Detention time (min) 20 40 60 80 100 Depth (m) 120 0.8 1.6 2.4 3.2 4.0 39 26 23 20 17 56 42 36 30 25 67 55 48 40 34 73 65 57 51 45 76 68 64 58 52 81 75 69 64 59 You are asked to assess whether the claimed performance of such sedimentation basin could be achieved and to suggest appropriate measures for improvement if needed.