How is chemical oxygen demand (COD) defined?

Chemical oxygen demand (COD) is defined as the amount of chemically consumed oxygen in a water sample. This measurement indicates the amount of oxygen that would be required to oxidize all organic and inorganic matter in the water, providing a measure of water quality that reflects the presence of pollutants. COD is crucial in assessing the impact of wastewater on the environment; higher COD values suggest higher levels of organic materials, which can lead to oxygen depletion in aquatic ecosystems.

The focus on chemically consumed oxygen distinguishes COD from biochemical oxygen demand (BOD), which measures the oxygen consumed by specific microbial activity over a certain timeframe. COD is often used because it can be determined quickly with standardized chemical methods, making it a practical tool for environmental monitoring and wastewater treatment processes. Understanding COD is essential for environmental health specialists, as it helps in evaluating water treatment efficiency and regulatory compliance for discharges into waterways.