What does the presence of BOD indicate about wastewater quality?

The presence of Biochemical Oxygen Demand (BOD) in wastewater is a crucial indicator of water quality, specifically relating to the amount of organic matter present. When BOD levels are high, it means that there is a significant amount of organic material in the water that microorganisms can decompose. This process of decomposition consumes oxygen, which is why BOD is measured; it reflects the demand for oxygen by these microorganisms. Therefore, a high BOD level signifies a greater concentration of organic pollutants in the water, pointing to poor water quality.

This understanding is fundamental in wastewater treatment because it indicates that the water has not been adequately treated and may require further cleaning to remove the organic matter before it can be safely released into the environment or reused.