PART B 1. A BOD analysis was conducted on a treated sewage at 20C. A quarter volume of sewage portion was added for the BOD analysis and the dissolved oxygen values listed below were measured (Table 1.0). By considering minimum dissolved oxygen at day-7 is valid for BOD test, determine the following: Table 1.0: Dissolved oxygen values Time (t) Dissolved Oxygen (mg/L) 0 8.3 1 6.7 2 5.4 3 4.8 5 6 ? 2.2 7 ? (a) Reaction rate K20 (b) BODs at 20C based on the drawn graph. (c) BOD, at 30C (d) Estimate the COD for the tested sample. Comment your answer. (10 marks)