Abstract: To address the issue that biological denitrification systems are prone to being impacted by copper-containing wastewater, leading to a significant decline in denitrification efficiency, this study optimized the culture factors ofPseudomonas hunanensisSK-4 through a three-step method combining the Plackett-Burman test, the steepest ascent test, and the response surface test. The results of the Plackett-Burman test indicated that the oscillation speed, pH, and inoculation amount had the most significant impact on the denitrification performance of strain SK-4. Moreover, Cu2+ at a mass concentration of 30－50 mg/L did not significantly affect the denitrification efficiency of strain SK-4, demonstrating its strong tolerance to Cu2+. The response surface test revealed that under conditions of pH 7.83, an inoculation amount （volume fraction） of 3.95%, and an oscillation speed of 149.21 r/min, strain SK-4 can achieve an optimal removal rate of NH+4-N of 82.33%. In the actual wastewater pilot test, even under the stress of 35.31 mg/L Cu2+, strain SK-4 could still efficiently degrade pollutants, with removal rates of TN, NH+4-N, NO－3-N, and COD reaching 93.79%, 98.52%, 85.42%, and 89.90%, respectively. This study optimized the nitrogen metabolism efficiency of strain SK-4 in copper-containing wastewater, verified its practical application potential, and provided a new treatment approach for the biological treatment of copper-containing wastewater.

Key words: biological denitrification, heterotrophic nitrification-aerobic denitrification, response surface, copper-containing wastewater, industrial water treatment