Question

Which is the correct ascending arrangement of BOD of sewage(S) distillery effluent(DE), paper mill effluent(PE) and sugar mill effluent(SE)?

• A. SE$<$PE$<$S$<$DE
• B. PE$<$S$<$SE$<$DE
• C. S$<$DE$<$PE$<$SE
• D. SE$<$S<$PE$<$DE

Answer 1

Answer: (B)

PE$<$S$<$SE$<$DE

• BOD is the Biological Oxygen Demand that is created when there is an excessive quantity of the organic matter in the water body and its decomposition is initiated by the decomposing bacteria. More the amount of organic waste, the higher will be the BOD and so more will be pollution in the water body.
• This causes an extreme reduction in the dissolved oxygen and suffocates the aquatic animals.
• Distillery effluent is rich in organic waste left from alcoholic fermentation and it has the highest BOD.

Sugar mill effluent follows the distillery effluent in the concentration of organic content. The sewage water contains the excreta and detergents mixed with it.

• Papermill effluent has the lowest concentration of the organic mass.

Hence, the correct answer is 'PE< S< SE< DE'.