Which of the following is NOT a biological characteristic of wastewater?

Chemical Oxygen Demand (COD) is not considered a biological characteristic of wastewater; rather, it is a measure of the total amount of oxygen required to chemically oxidize organic and inorganic matter in water. COD provides an estimate of the amount of pollutants present in wastewater that can be oxidized, but it does not specifically indicate the biological capacity or activity within the wastewater.

In contrast, Biological Oxygen Demand (BOD) is a crucial biological measure, as it assesses the amount of oxygen consumed by microorganisms while breaking down organic matter in water. This reflects the degree of organic pollution and the potential impact on receiving waters from a biological standpoint.

The presence of nitrogen is also a biological characteristic, as nitrogen compounds can influence the growth of microorganisms and are integral components of biological processes, particularly in the nitrogen cycle. Additionally, the microbial population represents the living organisms in wastewater that contribute to its treatment through biological processes, further emphasizing their importance in biological assessments.

Thus, recognizing the distinctions between chemical and biological measures is essential for understanding wastewater management and treatment practices.