Question

A more experienced colleague mentions to you that you should aim for a dissolved oxygen concentration around 1.0 mg/L at day 5 of the experiment. They show you data from a similar wastewater spill that happened last year, in which the BOD5 of the stream water was 60 mg/L. From your previous experiment, you found that the dissolved oxygen concentration at day 0 was 10 mg/L. Based on this information, what dilution factor, P, should you try in your reactor?

Answer 1

Answer:

3

Explanation:

Lt= Loe^(-kt)

Data:

Lo = 10 mg/mL

Assume k = 0.23/da

1. Calculate L5

L5 = 10e^(-5×0.23) = 10e^-1.15 = 10 × 0.317 = 3.17 mg/mL

2. Calculate the dilution factor

You expect to find L5 to be about 3

You want L5 to be about 1.

You should use a dilute your sample by a factor of 3.

P = 3