Which method is commonly used to evaluate the performance of wastewater treatment plants?

The assessment of wastewater treatment plants primarily focuses on the removal of organic matter and pollutants, which is effectively evaluated using Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) tests. BOD measures the amount of oxygen consumed by microorganisms in the decomposition of organic matter over a specific period, typically five days at a specific temperature. This allows for an understanding of the organic load and the treatment plant's capability to reduce it.

COD, on the other hand, measures the total quantity of oxygen required to oxidize both biodegradable and non-biodegradable contaminants. It provides insight into the overall amount of organic pollutants present in the wastewater. The comparison of BOD and COD results helps in evaluating the efficiency of the treatment process and ensures that the plant meets regulatory discharge requirements.

Using BOD and COD tests gives a comprehensive assessment of the treatment processes, including the performance of aerobic and anaerobic digestion, and monitoring effluent quality for environmental compliance. Other methods, while valuable, do not provide the same direct indicators of treatment performance in terms of organic matter removal and operational efficiency.