Isolation,identification and characterization of two mesophilic strains for nitrogen removal

Abstract:

[Objective] To address the low efficiency of biological nitrogen removal from high-temperature coal chemical wastewater.[Methods] In this study,a mesophilic ammonia-oxidizing bacterial strain A1 and a mesophilic denitrifying bacterial strain D1 were isolated from the activated sludge of the coal chemical wastewater treatment system of an energy and chemical group Co.Ltd.in Shanghai.[Results] Based on the morphological,physiological,and biochemical characteristics and 16S rRNA gene sequence,strain A1 was preliminarily identified as Aquamicrobium ahrensii and strain D1 as Pseudomonas stutzeri.The single factor experiments showed that the optimal growth temperatures of strains A1 and D1 were as high as 42℃ and 40℃,respectively.Then,we simulated the wastewater treatment at the initial NH₄⁺-N concentration of 100 mg/L and 42℃,and established a co-culture composed of strains A1 and D1(W/W,20%/10%) to explore the effects of the co-culture on shortcut nitrification and denitrification and N₂O release at different pH and C/N ratios.At 42℃,pH 9.0–10.0,and initial C/N ratio of 2:1,the co-culture showed a nitrogen removal rate above 99.0% and the maximum N₂O yield of 51.3%.[Conclusion] This study can provide technological support and strain resources for the biological treatment of high-temperature coal chemical wastewater,and help to reveal the law of N₂O release in the treatment of high-temperature wastewater.