Thank you for reporting, we will resolve it shortly
Q.
BOD increased by:
Rajasthan PMTRajasthan PMT 2004
Solution:
$BOD$ is the amount of oxygen required for biological oxidation by microbes in any unit volume of water. due to addition of sewage and waste organic material. Oxygen level is depleted and $BOD$ increases. Water bloom causing algae release great amount of organic matter upon the death of blooms into water body. It leads to increase in population of bacteria which in turn leads to depletion of available oxygen hance, $BOD$ increase.