What does the Chemical Oxygen Demand (COD) test measure?

The Chemical Oxygen Demand (COD) test measures the amount of oxygen that is required to chemically oxidize organic matter in a water sample. This test is crucial for assessing the level of organic pollutants present in wastewater and can provide insights into the water's overall quality. A high COD value indicates a high concentration of organic material, which may lead to oxygen depletion in aquatic environments, adversely affecting aquatic life.

By focusing on the chemical oxidation process, the COD test differentiates between biodegradable and non-biodegradable substances, giving operators valuable information for treatment processes. This parameter is vital for effective management of wastewater treatment facilities, ensuring that effluent discharged into the environment meets regulatory standards and minimizes environmental impact.

In contrast, the other choices focus on different aspects of water quality assessment, which do not align with what the COD specifically measures. For instance, assessing the presence of heavy metals pertains to toxic pollutants rather than organic matter. The concentration of dissolved oxygen is a separate metric that indicates the water's ability to support life, while total suspended solids measure particulate matter rather than the oxygen demand related to chemical oxidation of organic materials. Understanding these distinctions underscores the significance of the COD test in the context of wastewater treatment.