Answer to Question #271776 in Chemistry for Belen

Question

1. Incoming wastewater, with BOD5 equal to about 200 mg/L is treated in a well-run secondary treatment plant

that removes 90% of the BOD. You are to run a 5-day BOD test with a standard 300 mL bottle, using a mixture

of treated sewage and the dilution water (no seed). Assuming that the initial DO is 9.2 mg/L,

a. Roughly, what maximum volume of treated wastewater should you put in the bottle is you want to have at

least 2 mg/L at the end of the test (filling the rest of the bottle with water)?

b. If you make a mixture of half water and half treated wastewater, what DO would you expect after 5 days?

2. A mixture consisting of 30 mL of waste and 270 mL of seeded dilution water has an initial DO of 8.55 mg/L;

after 5 days, it has a final DO of 2.40 mg/L. Another bottle containing just the seeded dilution water has an initial

DO of 8.75 mg/L and a final DO of 8.53 mg/L. Find the 5-day BOD of the waste.

Answer 1

refusal