Question

Limit of BOD prescribed by central pollution control board for the discharge of industrial and municipal wastewaters into natural surface waters, is
A.< 3.0 ppm
B.< 10 ppm
C.< 100 ppm
D.< 30 ppm

Answer 1

The Full form of BOD is biological oxygen demand. It is the measure of dissolved oxygen that is required by aerobic bacteria to decompose the organic material present in sample water.

Complete answer:
-Biological oxygen demand is a very important factor to determine the pollution level in the water, More BOD indicates more pollution and hence there is a certain limit prescribed by the central pollution control board so that water with a higher level of pollution is not released in natural water bodies.
-The Limit of BOD prescribed by the central pollution control board is less than 10 parts per million (ppm).
-BOD is similar to COD which is the chemical oxygen demand but BOD measures the dissolved oxygen demand more specifically because BOD only measures biological oxidation whereas COD measures chemical oxidation.
-Sometimes due to microbial action on organic material causes depletion of oxygen in the water which can lead to the death of fishes and other aquatic organisms.

Option B: The limit of BOD is < 10 ppm for water to be released in natural water bodies because a BOD level greater than 10 ppm indicates relatively higher pollution which if released to the natural water surface will pollute natural water bodies as well. Therefore, this is the correct option.

So, the correct answer is Option B.

Note: There are many methods to determine the BOD of water, most commonly used method is the Winkler method which involves redox titration of iodine and thiosulfate, other methods to determine BOD includes the manometric method, polarographic method, dilution method, Software BOD sensor, Biosensor device, etc.