Author
 |
Brazil, Brian |
|
Submitted to: Aquaculture Magazine
Publication Type: Trade Journal Publication Acceptance Date: 4/1/2004 Publication Date: 7/20/2004 Citation: Brazil, B.L. 2004. Application of denitrification in aquaculture. Aquaculture Magazine. Vol. 30, pg 44-47. Interpretive Summary: Technical Abstract: Effluent treatment strategies vary from implementing best management practices (BMPs) to applying of end of the pipe removal processes. Denitrification is a process that can be used either to limit the waste requiring final treatment and/or as the final treatment process. In aquacultural effluents, nutrient (nitrogen, phosphorous, and carbon) and solids are the primary concerns. Nitrogen typically exists in the form of ammonia or nitrate while phosphorous is generally available in a soluble reactive form. During denitrification, heterotrophic bacteria metabolize available carbon compounds using nitrate as the electron acceptor when oxygen is not present. Nitrogen (as ammonia) and phosphorous are utilized as the microbes synthesize additional biomass. During the reduction of nitrate, nitrite and other intermediate nitrogen species are formed. Nitrite is the primary species of concern because it can accumulate to concentrations that are problematic to fish. This can be prevented by ensuring that sufficient carbon resources are available to fuel the process to completion. Carbon sources can be obtained from external sources such as methanol, however, the ideal carbon source for aquaculturists would be to utilize carbon sources within the fish culture system. This has been accomplished by anaerobically digesting waste solids to generate organic acids, such as acetate and propionate, that denitrifying bacteria can consume as fuel for the process. As a result of employing these processes, aquaculture facilities can realize a reduction in the mass of solids requiring final disposal as well as significantly reduce levels of nitrogen and phosphorous in their effluent. |
