Why using phosphate buffer and magnesium sulphate and calcium chloride and ferric chloride for dilution water in BOD5 test?

Answer 1

magnesium sulphate, calcium chloride and ferric chloride are added to provided optimum environment and phosphate buffer is added to slow down the rate of death of microbes.

Answer 2

Phosphate buffer helps maintain the pH of the dilution water, which is crucial for proper bacterial activity in the BOD5 test. Magnesium sulfate, calcium chloride, and ferric chloride provide essential nutrients for the bacteria to thrive and efficiently break down organic matter during the test. These chemicals help create an environment that supports the growth and metabolic activity of the microorganisms responsible for oxygen consumption in the BOD5 test.