Question 3: [26 marks] The sewage is flowing at 4.5 MLD from a primary clarifier to a standard rate trickling filter. The 5 day biological oxygen demand (BOD) of the influent is 160 mg/L. The value of the adopted organic loading is to be 160 g/m'.d and the surface loading is 2000 L/m.d. The circulation ratio (QQ) can be taken as 1.5. Determine; a) the volume and depth of filter in mand m respectively and [18 marks] b) the efficiency of filter unit in %. [8 marks]