Correct Answer - Option 3 : deoxygenation
Explanation:
When wastewater is discharged into the stream, the DO level in the stream goes on depleting. This depletion of DO content or exertion of BOD by microorganism is known as deoxygenation. Generally, the unit for deoxygenation constant is taken as per day.
The rate of deoxygenation depends upon the amount of organic matter remaining to be oxidized at any time t, as well as temperature (T) at which reaction occurs.
Rate of deoxygenation is given by,
\({K_D}_{T^\circ C} = {K_D}_{20^\circ C}{\left[ {1.047} \right]^{\left( {T^\circ C - 20^\circ C} \right)}}\)
Here, T = Temperature in ℃.
Hence, the rate of deoxygenation depends upon the temperature of the diluting water.
