What is the percent COD removal by an industrial waste treatment process if the influent COD is 285 mg/L and the effluent COD is 96 mg/L?

• A. 50%
• B. 75%
• C. 66%
• D. 80%

Answer: (C)

To determine the percent removal of Chemical Oxygen Demand (COD) in the wastewater treatment process, you can use the following formula:

Percent COD removal = [(Influent COD - Effluent COD) / Influent COD] × 100

Given the influent COD of 285 mg/L and the effluent COD of 96 mg/L, the calculation would be:

1. Calculate the COD reduction by subtracting the effluent COD from the influent COD:

COD reduction = 285 mg/L - 96 mg/L = 189 mg/L

2. Determine the percent COD removal by dividing the COD reduction by the influent COD and multiplying by 100:

Percent COD removal = (189 mg/L / 285 mg/L) × 100

3. Perform the calculation:

Percent COD removal ≈ 0.6632 × 100 ≈ 66.32%

Rounded to the nearest whole number, this value indicates that approximately 66% of the COD is removed in the treatment process. Therefore, the correct answer reflects the calculated percent removal, making it the most accurate choice for the percent COD removal in this scenario.