Aprimary clarifier with a hydraulic retention time of 1.5 hours is to be used in a wastewater treatment plant expected to treat a waste with a suspended solids concentration of 200 mg. l-1. the average flow is 910 m3-d-1. the ratio of the length to width of the tank is 3.0. the removal efficiency is estimated at 60%. the tank is to be rectangular and a collection mechanism for a 3.048 m wide tank is planned. the sludge is to be removed once a day, and the solids concentration of the raw primary sludge is expected to be 4% solids. density of sludge is 833 kg-m-3. a single effluent weir at the end of the tank is to be used. determine: (i) the required tank capacity; (ii) the required dimensions of the tank; (iii) the expected production of sludge; (iv) the size of the sludge holding tank; (v) the overflow rate; (vi) the weir loading; (vii) does the design satisfy the suggested standards for a primary clarifier? if not, suggest an arrangement that will meet these standards.