Novel aquaculture wastewater treatment by an efficient nitrogen-removing bacterium capable of simultaneous nitrification and denitrification

Abstract

Nitrogen pollution from aquaculture effluent poses a severe threat to aquatic ecosystems, necessitating efficient treatment solutions. In this study, a highly effective nitrogen-removing bacterium, designated SA20, was isolated from an aquaculture wastewater treatment system and identified as Paracoccus sp. Safety evaluations confirmed its non-hemolytic nature and broad antibiotic sensitivity, indicating its potential for safe application. Under optimized conditions (C/N ratio 16, 30 ℃, 140 rpm), the strain demonstrated complete removal of ammonium and nitrite, with over 95 % nitrate removal within 24 h. Nitrogen balance analysis revealed that approximately 70–80 % of total nitrogen was converted to gaseous form through denitrification, while 20–30 % was assimilated into biomass. When applied to actual aquaculture wastewater, SA20 achieved significant removal of various nitrogen forms, with total nitrogen removal exceeding 65 %. These findings demonstrate the potential of strain SA20 for practical application in aquaculture wastewater treatment, offering a promising biotechnology solution for sustainable aquaculture development.