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The influent of sewage treatment plant has a TSS concentration of 180 mg/L. What

ID: 1710366 • Letter: T

Question

The influent of sewage treatment plant has a TSS concentration of 180 mg/L. What is the concentration of suspended solids in the plant effluent if the plant is achieving a 90% TSS removal efficiency? (b) If the flow rate is 10 mgd, how many pounds of solids are discharged per day into the receiving stream? A trickling filter has a diameter of 20 m and a depth of 2.5 m. It is operated with a direct recirculation ratio of 1.0, and the influent sewage flow rate is 3 ML/d. Influent BOD to the primary tank is 200 mg/L. and the BOD removal efficiency in the tank is 35 Percent Compute both the hydraulic load and the organic load on the tricking filter. Hydraulic load: _____ Organic load: _____

Explanation / Answer

13. a.) Efficiency of treatment plant = ( Influent - effluent TSS ) / Input TSS

Given TSS concentration = 180 mg/l

efficiency = 90%

Therefore, 0.9 = ( 180 - Effluent ) / 180

Effluent = 18 mg/l

TSS concentration in the effluent = 18 mg/l

b.) Flowrate = 10 MGD = 37854118 lit /day

TSS in effluent = 18 * 37854118

= 681374124 mg/day

= 1502.172 lb/day.

14.)

area of filter = Pi* 100 = 314.159 m2

Hydraulic load = 3 / area of filter

= 3 / 314.159

= 9549.3 l/day/m2

Efficiency = 35 % , So 65% of BOD is going to trickling filter

BOD to trickling filter = 0.65 * 200 = 130 mg/l

Organic load = BOD * flow rate   

= 130 * 3

= 390 kg BOD / day