BOD & COD Reduction
Biological oxygen demand (BOD) is a measure of the amount of oxygen that is consumed by bacteria during the decomposition of organic matter.  Having a safe BOD level in wastewater is essential to producing quality effluent. If the BOD level is too high then the water could be at risk for further contamination, interfering with the treatment process and affecting the end product.

There are several factors that can contribute to high BOD levels: nitrates and phosphates present in the wastewater, water temperature, and others. Each factor affects the plant life in the water, such as algae, and in turn also has an effect on the organisms that help decompose water contaminants in the wastewater treatment process. The best quality wastewater treatment will occur in an environment that supports the life of these bacteria while maintaining a controlled population of them so as to not encourage rapid bacterial decomposition, which would create  higher BOD levels.

Similar to BOD is chemical oxygen demand (COD). COD measures the amount of oxygen that is consumed by the water in the decomposition and oxidation processes, specifically the decomposition of organic matter and oxidation of inorganic matter, or chemicals. COD is an application that is usually used in industrial settings; however, municipalities treating wastewater with chemical pollutants may use it.