Biochemical Oxygen Demand (BOD) is the amount of dissolved oxygen that aerobic biological organisms need to break down organic material present in water. BOD is stored in the cell as a polysaccharide. If this type of growth is excessive, it can lead to slime bulking and settling problems at wastewater treatment plants. It can also lead to foaming problems.

Treatment systems often require supplemental carbon as a food source plus nitrogen and phosphorus to maintain a healthy microbial community during production stoppages or as a readily available substrate during start-ups. An established microbial community prefers a steady stream of food, but some production facilities may not run continuously. During downtimes, the microbial community can starve if insufficient BOD is available. Nutrient products, like BioAid®, can help supplement nutritionally poor wastewater and balance the BOD at wastewater treatment plants.