Rapid and efficient nitrogen removal by a novel heterotrophic nitrification-aerobic denitrification bacteria...

Efficient nitrogen removal from aquaculture wastewater is crucial for environmental sustainability. A novel strain, Marinobacterium maritimum 5-JS, exhibiting HN-AD capabilities, was isolated from a sea cucumber aquaculture pond. This strain demonstrated remarkable nitrogen removal efficiencies, achieving nearly 100% elimination of NH₄⁺-N, NO₃^--N and NO₂^--N within 18 h. Strain 5-JS preferentially utilizes NH₄⁺-N in simultaneous nitrification and denitrification processes, with optimal removal achieved using sodium citrate as a carbon source, a C/N ratio of 11, pH 8.0, and at a temperature of 30 °C. The metabolic pathway of strain 5-JS was elucidated, indicating its adaptability to high concentrations of Mg²⁺, Fe²⁺, and Mn²⁺ (up to 50 mg/L). When introduced into mariculture wastewater, strain 5-JS rapidly reduced concentrations of all three nitrogen compounds to undetectable levels within 8 h. These findings highlight the exceptional nitrogen removal capabilities of strain 5-JS and its potential for application in the biological treatment of aquaculture wastewater.