What is the primary purpose of chemical oxygen demand (COD) testing?

The primary purpose of chemical oxygen demand (COD) testing is to determine the amount of organic compounds present in water. COD measures the total quantity of oxygen that is required to oxidize both biodegradable and non-biodegradable organic matter, which makes it a critical parameter in evaluating water quality, especially in wastewater management.

Understanding the level of organic materials in water helps assess pollution levels and the potential impact on aquatic life. High COD values indicate a larger quantity of organic pollutants, which may deplete oxygen in receiving water bodies, adversely affecting aquatic ecosystems. Therefore, COD serves as a vital indicator of organic load, essential for environmental monitoring and compliance with water quality standards.

Other options relate to different aspects of water quality testing. For instance, measuring the pH level addresses acidity and basicity, assessing microbial activity focuses on the health of the ecosystem, and evaluating hardness pertains to the concentration of calcium and magnesium ions. However, none of these directly connect to the core purpose of COD testing in determining organic matter content, which is central to understanding potential environmental impacts and treatment needs.