A common problem in aerated stabilization basins (ASBs), is oxygen deficiency. Oxygen deficiency can arise for a variety of reasons, such as a power outage, aerators being down for maintenance, scavenging of oxygen by chemical compounds containing sulfur, or upstream production spills that increase organic loading to a WWTP. Under oxygen deficient conditions, oxygen supply may not meet O₂ demand, putting Biochemical Oxygen Demand (BOD) permit limits at risk of being violated. When this occurs, it is up to the environmental staff responsible to respond quickly with a solution to ensure that permit limits can be met. One solution available to correct this problem is the application of a nitrate salt in liquid form such as calcium nitrate (EBS CN-9).

During biological wastewater treatment, organic compounds are removed by bacteria using two linked processes: catabolism and anabolism. This entire process collectively referred to as metabolism, hinges on the availability of a terminal electron acceptor. If oxygen is available, the bacteria will use it as a terminal electron acceptor since it provides the most energy. However, if oxygen is not available, such as during oxygen deficient conditions, the bacteria are forced to find a new terminal electron acceptor so that BOD removal can continue. After O₂, the second most energetically favorable terminal electron acceptor for bacteria to use is nitrate (NO₃^–). The application of CN-9 provides a cost-effective solution to an oxygen deficiency problem to help ensure that BOD removal continues at an adequate rate.

When comparing the reactions of using O₂ or NO₃^– as a terminal electron acceptor, every 1 part of NO₃^––N is the equivalent of 2.86 parts of O₂S. Therefore, every 24-ton truckload of EBS CN-9 provides the equivalent of approximately 11,600 lbs of O₂ or BOD removal potential or 3 lbs of BOD removal potential for every gallon applied.

The application of EBS CN-9 provides a scientifically-sound solution to help ensure that BOD permit limits can still be met during oxygen deficient conditions and it offers supplemental benefits. It can be handled and stored safely on-site in plastic or fiberglass tanks and its by-products are harmless. EBS CN-9 is highly soluble in water, and nitrate is non-volatile so it will remain in the wastewater until utilized by the bacteria. Finally, EBS CN-9 prevents hydrogen sulfide (H₂S) formation when utilized appropriately because nitrate is a more favorable terminal electron acceptor than sulfate (SO₄^2-), which if utilized as a terminal electron acceptor results in the formation of H₂S as a by-product. If nitrate is available, the bacteria will use it over sulfate as a terminal electron acceptor preventing H₂S formation as nitrate yields more energy.