Question

Which one of the following is correct?

• A. The partially treated effluent from a food processing industry, containing high concentration of biodegradable organics, is being discharged into a flowing river at a point P. If the rate of degradation of the organics is higher than the rate of aeration, then dissolved oxygen of the river water will be lowest at point P.
• B. The most important type of species involved in the degradation of organic matter in the case of activated sludge process based wastewater treatment is chemoheterotrophs.
• C. For an effluent sample of a sewage treatment plant, the ratio BOD\(_{5\text{-day},20^\circ}\) upon ultimate BOD is more than 1.
• D. A young lake characterized by low nutrient content and low plant productivity is called eutrophic lake.

Hint:

Chemoheterotrophs are key microorganisms in wastewater treatment, as they degrade organic matter to remove pollutants.

Answer 1

The Correct Option is B

- Option (A) is incorrect because if the degradation rate exceeds the aeration rate, the dissolved oxygen would be lowest at the point of discharge.
- Option (B) is correct, as the primary organisms responsible for organic matter degradation in wastewater treatment using activated sludge are chemoheterotrophs, which use organic compounds as their source of carbon and energy.
- Option (C) is incorrect since the ratio of BOD5 to ultimate BOD is usually less than 1.
- Option (D) is incorrect; a lake with low nutrient content and low plant productivity is called an oligotrophic lake, not eutrophic.
Final Answer: The most important type of species involved in the degradation of organic matter in the case of activated sludge process based wastewater treatment is chemoheterotrophs.