Efficiency of trickling filter measured by?

• A. pH
• B. Ammonia
• C. BOD or COD
• D. Temperature

Answer: (C)

Trickling filters are evaluated by how well they remove organic matter from wastewater. That’s why BOD or COD is the best measure of their efficiency—these tests quantify the amount of organic material left after treatment. BOD reflects the oxygen that microbes would eventually need to oxidize the organics, while COD provides a faster chemical estimate of the same concept. By comparing influent and effluent BOD or COD, you can gauge how effectively the biofilm on the trickling media is breaking down organics. Temperature and pH influence microbial activity and ammonia levels indicate nitrification activity, but they don’t directly quantify overall organic removal the way BOD or COD do.