Question

For effluents generated by a molasses-based distillery and wood-based pulp and paper industry, which of the following statement(s) is/are NOT correct?

• A. Both the effluents have dark colour.
• B. Both the effluents have high toxicity.
• C. Both the effluents generally have BOD greater than 15{,}000 ppm.
• D. Both the effluents have high pH.

Hint:

Distillery effluents = high BOD, acidic; paper-mill effluents = moderate BOD, alkaline.

Answer 1

The Correct Option is B, C, D

Step 1: Distillery effluent characteristics.
Molasses-based distilleries generate spent wash that is very dark in colour, acidic (low pH), and has extremely high BOD often exceeding 40{,}000–50{,}000 mg/L.
Step 2: Pulp and paper mill effluent characteristics.
These effluents are brown in colour, contain lignin and suspended solids, have moderate BOD (300–1500 mg/L), and usually have neutral to slightly alkaline pH.
Step 3: Evaluate statements.
(A) Both have dark colour — correct.
(B) Both have high toxicity — incorrect; distillery effluent is highly toxic but paper-mill effluent is less toxic.
(C) Both have BOD>15{,}000 ppm — incorrect; true for distillery, not for paper mill.
(D) Both have high pH — incorrect; distillery effluent is acidic.
Thus incorrect statements are (B), (C), (D).
Final Answer: (B), (C), (D)