The final effluent dissolved oxygen of a properly operating trickling filter plant typically falls within 1.25 to 2.0 mg/L. This statement is:

The final effluent dissolved oxygen of a properly operating trickling filter plant typically falls within 1.25 to 2.0 mg/L. This statement is:

• A. True
• B. False
• C. Not applicable
• D. Unknown

Answer: (A)

Dissolved oxygen in the final effluent shows how much oxygen is left after treatment and how well the system is aerating and handling the organic load. In a properly operated trickling filter plant, the oxygen balance typically leaves the effluent in a moderate range, about 1.25 to 2.0 mg/L. This reflects enough remaining oxygen to avoid hypoxic discharge while not being so high that energy is wasted or the process is overaerated. If the DO falls significantly below this range, the plant may be undersized or overloaded and consuming more oxygen than is replenished. If DO is consistently higher, it could indicate excessive reaeration or other factors increasing DO, but under normal operation the final effluent DO tends to fall within that 1.25–2.0 mg/L band. Therefore the statement is true.

Dissolved oxygen in the final effluent shows how much oxygen is left after treatment and how well the system is aerating and handling the organic load. In a properly operated trickling filter plant, the oxygen balance typically leaves the effluent in a moderate range, about 1.25 to 2.0 mg/L. This reflects enough remaining oxygen to avoid hypoxic discharge while not being so high that energy is wasted or the process is overaerated. If the DO falls significantly below this range, the plant may be undersized or overloaded and consuming more oxygen than is replenished. If DO is consistently higher, it could indicate excessive reaeration or other factors increasing DO, but under normal operation the final effluent DO tends to fall within that 1.25–2.0 mg/L band. Therefore the statement is true.