Question

A good quality of water will have:
$A.$ High $DO$ (Dissolved oxygen)
$B.$ High $BOD$ (Biochemical Oxygen Demand) and high $COD$ (Chemical Oxygen Demand)
$C.$ High $COD$ (Chemical Oxygen Demand) and high $DO$ (Dissolved Oxygen)
$D.$ All of the above

Answer 1

There are many parameters that determine the quality of water such as Dissolved Oxygen, Biochemical Oxygen Demand, and Chemical Oxygen Demand. These parameters are necessary for the analysis of water.

Complete step by step answer:
Water has many sources that are a pond, well, river, and tap water but the good quality of water which has more dissolved oxygen present in it, Dissolved oxygen is essential for all living organisms. So, good quality water contains a greater amount of Dissolved oxygen. More the dissolved oxygen present in water than water is purer. Higher $BOD$ decreases the dissolved oxygen that is available in water that is being consumed by the bacteria. Since less dissolved oxygen is available in water, fish and other microorganisms may not survive. When the $COD$ level increases the amount of oxidizable organic material also increases which will reduce dissolved oxygen $DO$ level. The correct answer is option “A” .

Additional Information :
- Dissolved oxygen $\left( {DO} \right)$: Dissolved oxygen is a measure of how much oxygen is dissolved in the water. The amount of oxygen available for living organisms. The amount of dissolved oxygen present in water tell us about the quality of water
- Biochemical oxygen Demand $\left( {BOD} \right)$ : $BOD$ is the amount of oxygen consumed by bacteria while decomposing organic matter under aerobic conditions
- Chemical oxygen Demand $\left( {COD} \right)$ : $COD$ is the amount of oxygen required for the oxidation of total organic matter present in water.

Note: The dissolved oxygen level in natural and wastewater depends on the physical, chemical, and biochemical activities of the water bodies. Oxygen is considered poorly soluble in water. Its solubility is related to pressure and temperature and pressure. At low temperature $DO$ is high and at high temperature $DO$ is low.