Aerobic denitrifying bacterium SY-D-22: isolation, optimization of denitrification conditions, and characterization of denitrification mechanism

Abstract:

[Background] In the treatment of wastewater containing nitrate, common microorganisms cannot efficiently remove nitrate while having a high removal rate for total nitrogen, which results in the use of multiple bacteria or complex processes.[Objective] To efficiently and safely remove nitrate nitrogen and total nitrogen from water. [Methods] An efficient aerobic denitrifying bacterium was isolated from activated sludge and sequenced for the 16S rRNA gene. The response surface methodology was employed to optimize the factors affecting nitrogen removal. Further, the denitrification capacity and characteristics of the strain for nitrate-containing wastewater were studied. [Results] An efficient aerobic denitrifying bacterium SY-D-22 was isolated from activated sludge and identified as Staphylococcus. The best denitrification efficiency of the strain was achieved under pH 8.18, C/N ratio of 13.39, 31.43℃, and 130 r/min. With sodium citrate as the sole carbon source, strain SY-D-22 rapidly removed nitrogen under aerobic conditions, demonstrating the nitrate nitrogen (100 mg/L) removal rate up to 100% and the total nitrogen removal rate of 95.34%. [Conclusion] Staphylococcus SY-D-22 was isolated from the activated sludge. After the denitrification conditions were optimized by response surface methodology, the removal rates of the strain for nitrate nitrogen and total nitrogen was up to 100.00% and 95.34%, respectively. This strain is capable of removing nitrate nitrogen and nitrite nitrogen.