Problem 6 Provide answers to the following questions related to characterization of water contaminants and their measurements, biochemical axygen demand and sedimentation. (8) (0) A drinking water treatment plant uses groundwater under the influence of surface water infiltration in a heavily farmed community. Give one (1) chemical and one (1) microbiological contaminant that typically needs to be treated for from groundwater supplies. Provide one (1) treatment method for each contaminant type that may be used to ensure the water is potable. Briefly discuss how you would wse measurement methods to ensure that contaminants are sufficiently reduced below any aesthetic ( c. B, odour) or health effect ( eg. illness). (ii) A BOD test is condacted at standard temperarure conditions asing 250mL of secondary efluent mixed with 250mL of water. The initial DO in the mix is 10 mg/L. After 5 days, the DO is 3mg/L and after 20 days the DO has stabilined at 0.5mg/. Assume that nitnfication has been inhibited so that only CBOD5 (5-day carbonaceous biochemical oxygen demand) is being mensured. (3) (a) Calculate the 5-day CBOD of the secondary effluent in mg/L; and (3) (b) Estimate the uttimate CBOD in mig/L (6) (tii) Cive threc (3) important desige parameters for a primary sedimentation system (c. g. a primary clarifier in a wastewater treatment plant), briefly explain how the three (3) parameters influence the performance of the system and give typical design values (with dimensions for each parameter) used in any wassewater treatment applicatioe