A 11,385m3/d trickling filter (TF) plant consists of a primary clarifier, followed by two parallel equal flow single-stage trickling filters containing stone media, which is followed by two secondary-clarifiers. The influent to the wastewater treatment plant (WWTP) contains 150mg/L of BOD5 and the primary clarifier removes 35% of the BOD5. The temperature of the wastewater during the winter averages 14C. The diameter and depth of each TF is 24m and 2.5m respectively. A recycle ratio (r=Qt/Q) of 1.0 was used for each TF. Design this biological treatment system by estimating the following parameters: i) efficiency of separation of each TF at 14C(E14) and ii) effluent BOD5 concentration from each TF in mg/L. [17 marks] [3 marks]