Sanitary & environmental engineering

Sedimentation + flocculation Clariflocculator Sedimentation + flocculation This unit will include a central flocculation chamber surrounded by a sedimentation chamber (خزان الترويب + خزان الترسيب مع بعضهم)   Purpose Removal of 50 -96% of suspended solids and colloidal matters Design data Outer tank To = [(1/3 + ½)hr + (2---4)hr] do = 3 ---- 5m  ≥ 35 m Vo = [Q / n π do(r + 1)]

Vi > 0.3 m/sec حتى لا يحدث ترسيب للرمل < 1 m/sec Inner tank To = (1/3 + ½)hr di = do – (0.5--- 1)m i = (1/3 + ½)o Vi > 0.3 m/sec حتى لا يحدث ترسيب للرمل < 1 m/sec Surface loading rate = S.L.R. = over flow rate = O.F.R = 25-40 m3/m2/day Sed. Tan يعبر عن المركبة الرئيسية للسرعة داخل = Q / net surface area Qd / = Qd / n (π/4) (o2-i2) Hydraulic load in outlet weir = Qd / n π do > 150 m3m2/day حتى يكون التصميم اقتصادي < 300 m3m2/day حتى لا يحدث دوامات ملحوظة S.L.R. ≤ 25 حتى يكون التصميم اقتصادي (أي لا تزيد o كثيرا) S.L.R. ≥ 40 حتى لا تزيد المركبة الرأسية للسرعة وبالتالي يقل طول مسار المياه وبالتالي يقل زمن بقاؤها في الخزان وبالتالي تقل الكفاءة

Steps of design of claiflocculator Outer tank (sed. Zone) To = [(1/3 + ½)hr + (2---4)hr] Co = Qd * To Assume do = 3 ---- 5m S.A.o = Co / do To get nmin Assume o = max = 35 m ao = π o2 / 4 nmin = S.Ao / ao   Inner tank (Flocc.. Zone) Assume Ti = [(1/3 + ½)hr Ci = Qd * Ti di = do – (0.5 --- 1)m S.A.i = Ci / di ni = no = nmin S.A.i = ni + ai = ni * Ci / di * π i2 / 4 Get i

Checks: i/ o = 1/3 ---- 1/2 S.L.R. = Qd / (S.Ao-SiAi) = 25-40 m3m2/day Hyd. load on outlet weir = Qd / n π o = 150-30 m3m2/day Vh = Qd / [n π do (i + 1)] ≥ 0.3 m/min

Design data (accoletor) Ti = 15 --- 20 min To = 1 ---1.5 hr Alum doze = 0.25 – 0.5 alum doze in clariflocculator i ave / o ave = 1/3 ---1/2 S.L.R. = Qd / (S.Ao-SiAi) = 45-65 m3m2/day No. Vh Hydraulic load on outlet weir = Qd / n π o = 150---300 m3m2/day Always circular Overall efficiency = 98 %

Design data (pulsator) Ti = 5 --- 10 min To = 45 ---70 min Alum doze = 0.5 – 0.75 alum dose in clariflocculator (i / o)* (Li/Lo) * (Bi/Bo) = 1/3 ---1/4 S.L.R. = Qd / (S.Ao-SiAi) = 60-100 m3m2/day No. Vh Hydraulic load on outlet weir = Qd / n π o or Qd / n(21) (28) = 150---300 m3m2/day Circular of rectangular or square Overall efficiency = 97----99 %  

Design data (plate s) Ti = 5 min To = 30---45 min Alum doze ----- alum dose in clariflocculator di = do & Bi = Bo S.L.R. = Qd / (n * S.A. plates) = Qd / (nplates * L Bo)30-50 m3m2/day No. Vh Hydraulic load on outlet weir = Qd / n [(2L) + (28)] = 150---300 m3m2/day Always rectangulatr Overall efficiency = 99.5 % Plates =  30 ----60