Isolation and Identification of an Ammonia Nitrogen Removal Bacteria Strain with High Tolerance to Ammonia Nitrogen and Optimization of Its Removal Condition

An ammonia nitrogen removal bacteria strain N-2 with high tolerance to ammonia nitrogen was isolated and screened from soil heavily polluted by fermentation industrial wastewater by means of shake flask enrichment culture and plate domestication screening. Then the strain N-2 was identified through its morphological characteristics and phylogenetic analysis based on its 16S rDNA sequences. The maximum ammonia nitrogen tolerance concentration of the strain was verified by the simulated wastewater with high concentration ammonia nitrogen test. The optimum removal condition of N-2 was optimized by single factor and orthogonal test with the target of ammonia nitrogen removal rate to establish the theoretical foundation for its industrial application. The results showed that the N-2 strain with excellent comprehensive performance was identified as Lysinibacillus sphaericus. The N-2 strain could rapidly remove ammonia nitrogen in the simulated ammonia nitrogen wastewater within 10 h by bacterial assimilation without any accumulation of nitrate and nitrite, and could also grow normally with initial concentration of ammonia nitrogen up to 6000 mg/L. The best ammonia nitrogen removal conditions were C/N 10, inoculation volume 5%, pH8.0, temperature 31 ℃, speed 180 r/min and liquid volume 62.5 mL/250 mL. Under the optimal conditions, the removal rate of ammonia nitrogen was up to 97.7% for the initial concentration was 50 mg/L, 91.0% for 100 mg/L and 71.7% for 500 mg/L within 10 h. To sum up, the strain N-2 can not only quickly and efficiently remove ammonia nitrogen in water, but also has high tolerance to ammonia nitrogen. It can be used as a potential strain resource for removing ammonia nitrogen in industrial wastewater with high ammonia nitrogen concentration.