Multiple choice

With the presence of organic matter in water, _____________________________.

  1. the oxygen demand decreases

  2. the oxygen demand increases

  3. the oxygen demand remains unchanged

  4. the oxygen demand becomes random
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Biological Oxygen Demand (BOD) is a measure of the oxygen used by micro organisms to decompose the waste. If there is a large quantity of organic waste in the water supply, there will also be a lot of bacteria present , working to decompose this waste. In this case, the demand for oxygen will be high (due to all the bacteria) so the BOD level will be high. As the waste is consumed or dispersed through the water, BOD levels will begin to decline.

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