Abstract: In order to provide new strains for the natural rubber wastewater treatment process, strains that can effectively remove ammonia nitrogen were isolated and screened from natural rubber processing wastewater. A strain with the best nitrification ability was seleted by comparing the denitrification capacity, named JD-7. Based on 16S rDNA gene sequencing and morphological characteristics, the strain preliminarily identified as Bacillus sp. strain JD-7 can reduce the ammonia nitrogen mass concentration from the initial 98.24 mg/L down to 8.33 mg/L, the nitrogen removal rate reached 91.25% in 48 hours. The strain showed the ability to remove nitrate and nitrite, and the removal rates were 44.39% and 50.06%, respectively. Then, the nitrification ability of the strain under different environmental conditions (temperature, initial pH value and C/N ratio) was studied by response surface method. The results indicated that the strongest nitrification ability was observed with temperature of 30.35 ℃, initial pH of 7.85 and the C/N ratio of 6.13. The strain was put into different proportions of actual wastewater for small-scale experiments to determine the practical application effect of the strain. Under the optimal conditions, the ammonia nitrogen removal rate of JD-7 to the actual natural rubber processing wastewater can reach 131.48 mg/(L·d). Strain JD-7 has highly efficient denitrification ability, which demonstrated that the strain has great application potential for nitrogen removal in the treatment of natural rubber processing wastewater.

Key words: heterotrophic nitrification aerobic denitrification, Bacillus sp., natural rubber processing wastewater, nitrification characteristics, response surface