(15 points) A BOD test is run using 50 mL of treated wastewater mixed with 250 mL of pure water. The initial DO of the mix is 9.0 mg/L. After 5 days, the DO is 4.5 mg/L. After a long period of time, the DO is 2.5 mg/L, and it no longer seems to be dropping. Assume there is no nitrogenous BOD and that all BOD is carbonaceous. a. What is the 5-day BOD of the wastewater

27 mg/L

Explanation:

From the given information:

To determine the 5-day BOD using the formula:

where;

BOD = biochemical oxygen demand

= initial dissolved oxygen

= final dissolved oxygen

P = dilution factor

The dilution factor

where;

replacing the value of P into equation  (1);

answer

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