8 3 al 9 6 4 4 5 6 4 Problem 2: Water has a BOD5 of 10 mg/L. The initial Do in the BOD bottle is 8 mg/L and the dilution is 1:10. What is the final Do in the BOD bottle? Problem 3: Consider the following data from a BOD test: Day 0 1 2 3 4 5 6 7 D.O(mg/l) 9 9 8 7 6 3 If there is no dilution (i.e., the dilution factor is 1), what is the BOD5? Problem 4: Consider the following data for a BOD test. Day 0 1 2 3 D.O(mg/l) 9 8 7 6 5 4.5 Assume there is no dilution. i. Calculate BODS. ii. Plot the BOD versus time. Problem 5: A wastewater sample has kl = 0.2 day-and an ultimate BOD (L) = 200 mg/L. What is the final dissolved oxygen at five days in a BOD bottle in which the sample is diluted 1:20 and where the initial DO is 10.2 mg/L? Problem 6: The BOD5 of an industrial waste after pre-treatment is 220 mg/L, and the ultimate BOD is 320 mg/L. i. What is the deoxygenation constant kl (base 10)? ii. What is the deoxygenation constant kl (base e)? Problem 7: The ultimate BOD of each of two wastewater samples is 280 mg/L. For the first, the deoxygenation constant ki (base e) = 0.08 d-1, and for the second, kl = 0.12 d-1. What is the BOD5 of each? Show graphically how this can be so. Problem 8: BOD (at 20C after 5 days) of wastewater has been found to be 250 mg/l. The k value is known to be 0.23 per day. What should be BOD s, if the test was run at 25C? Assume k20 0.12 Problem 9: An analysis for BODs is to be run on a sample of wastewater. The BOD is expected to range from 50 to 350, and the dilutions are prepared accordingly. In each case, a standard 300-ml BOD bottle is used. The data are recorded below: Bottle no. Wastewater (ml) DO 1 20 8.9 1.5 2 10 9.1 2.5 i. Determine the BODs of the wastewater. ii. If you know that the oxygen utilization rate is 0.21 per day at 20C, what will be the BOD, if the test is run at 30C? DO