Question

2. A sanitation district is to install rapid sand filters downstream of the clarifiers. The design- loading rate is selected at 190 m/m per day. The design capacity of the waterworks is 0.30 m/sec. The maximum surface per filter is limited to 50 m² • a.) Design the number and size of filters (Assume the cross section of filters is square, determine the length of side); calculate the normal filtration rate base on your design. b.) A sieve analysis curve of the silica sand gives duo = 0.47 mm and do = 0.73 mm. What is its uniformity coefficient? Estimate the particle size of ilmenite sand (specific gravity = 4.2) that has the same settling velocity of silica sand (specific gravity = 2.6). Use the formula given in lecture and deo of silica sand.

Answer 1

Curen Datai Rapid Sand Filter CR8F). the design leading rate = 190 m²/m2/day the design capacity of hate head (@) = 0.3 m/ the Maximum surface Area filter = som (a) che of filter is square Total surface area Required 7 = for ROF (Rapid sand JS.A. I filth T. ROF C Lrading - Rate . .. . . .. = 450 0.3 x 24 x 60 x 60 (meday 190 (m/day) total wirface area = 136.4 m² 1 No of filters = total surface alla requized Area of single fill [ Assuming square filtre ut s om No of filters = 136.4 49 = 2.78 Number of filters. ~ 3 filters An Dimensions of filter your side rate filtration for Surface Normal = 49 m² area For thor = ac Design capacity) entire S. A Csurface area) Fore One - ROF =/0.3 x 24 x boxbo ). x t rentine system inst thrawon = 176.3 m3/m²/day Ane. . square filter la = 7m Tu M u linel system Fore Filter ts INO rate aut a 177