CWEA Grade 3 Lab Analyst Practice Exam

The analysis of Chemical Oxygen Demand (COD) is primarily used to determine the organic material content in water samples. COD measures the amount of oxygen that is consumed when organic matter in a sample is oxidized. This gives an indication of the level of organic pollutants present in the water, as higher COD values typically indicate a greater concentration of organic substances that can be biologically or chemically oxidized.

Understanding organic material content is crucial for assessing water quality and the potential impact of effluents on aquatic ecosystems. This information is important for wastewater treatment processes, as it helps in designing treatment systems and evaluating their effectiveness in removing organic pollutants.

Evaluating water density, temperature, or pH levels do not relate directly to COD analysis. Density would require separate measurements and methods involving the physical characteristics of water, temperature assessments are typically obtained with thermometers, and pH measurements are conducted using pH meters or indicators. While all these parameters are important in water quality assessment, they do not correlate with the COD measurement, which is specifically focused on organic load in the water sample.