Treated wastewater effluent is to be filtered using a shallow (500 mm) single-medium granular filter containing uniform sand with a size of 0,8 mm as filtering medium. If the average suspended solid concentration in the treated effluent is 35 mg/L, the filtration rate is 80 L/m2*min and the total available head loss is fixed at 3 m, estimate the length of filter run using the data given in figures 1b (0,75 mm) and 3.

Figures 1 a & b

Figure3

(a) (b) Relative concentration, CICO 1.0 0 0.5 0.5 1.0 VO 0.45 mm \ \ \ \ 200 0.60 mm 0.75 mm Depth from surface, mm Start of run 400 End of run Sand size = 0.5 mm Start and end of run for each sand site 600 FIGURE 12.32 Normalized suspended-solids removal curves as a function of depth and time as observed during (a) the filtration of a pretreated water (coagulation/flocculation sedimentation) and (b) the filtration of settled effluent from an activated sludge treatment process. In both instances, the filtration rate is about 80 L/m2 m. 5.0 Uniform sand (diameter in mm) Uniform anthrasite (diameter in mm) 1.0 0.5 7 Head loss (meters) 0.1 0.6 0.8 1.0 0.05 1.0 ULL 1.0 1.5 2.0 10.0 100.0 Suspended solids removal (mg/cm3) (a) (b) Relative concentration, CICO 1.0 0 0.5 0.5 1.0 VO 0.45 mm \ \ \ \ 200 0.60 mm 0.75 mm Depth from surface, mm Start of run 400 End of run Sand size = 0.5 mm Start and end of run for each sand site 600 FIGURE 12.32 Normalized suspended-solids removal curves as a function of depth and time as observed during (a) the filtration of a pretreated water (coagulation/flocculation sedimentation) and (b) the filtration of settled effluent from an activated sludge treatment process. In both instances, the filtration rate is about 80 L/m2 m. 5.0 Uniform sand (diameter in mm) Uniform anthrasite (diameter in mm) 1.0 0.5 7 Head loss (meters) 0.1 0.6 0.8 1.0 0.05 1.0 ULL 1.0 1.5 2.0 10.0 100.0 Suspended solids removal (mg/cm3)