纳米铜对自养脱氮亚硝化工艺的短期及长期影响

为考察纳米铜对自养脱氮亚硝化工艺的影响,在SBR反应器内分别进行短期影响实验(8 h)及长期影响实验(20 d),研究氨氮氧化速率、氮素转化规律及污泥性能的变化规律.短期实验结果表明,低质量浓度的纳米铜(≤1 mg/L)对亚硝化有促进作用,纳米铜质量浓度在3~30 mg/L内严重抑制自养脱氮亚硝化,氨氮氧化速率降低率为21.9%~44.9%.纳米铜为50 mg/L时,由于质量浓度过高导致纳米颗粒团簇,降低了真正作用于细胞的量,亚硝化活性得到强化.长期实验结果表明,长期暴露在低质量浓度(1 mg/L)的纳米铜环境中,氨氮氧化速率受到严重抑制,氨氮去除率从90%降低为44.8%,氨氧化细菌比亚硝酸盐氧化细菌对纳米铜更加敏感.在长期作用后,污泥中的铜含量增加,胞外聚合物含量增加,解除纳米铜抑制后,两者均降低.纳米铜对自养脱氮亚硝化工艺的微生物活性、脱氮能力、污泥性能均具有较大的影响.

Short-term and long-term effects of Cu nanoparticles on partial nitrification process

The short-term and long-term effects of Cu nanoparticles (NPs) on partial nitrification (PN) process were studied in SBR. The ammonia oxidation rate, nitrogen removal and sludge property were analyzed within exposure of different concentrations of Cu NPs. The short-term result suggested that the Cu NPs with 1 mg/L was beneficial for PN process, while the NPs in 3-30 mg/L significantly inhibit PN. As a result, the ammonia oxidation rate decreased to 21.9%-44.9% of the initial value. When the Cu NPs was 50 mg/L, the PN process was enhanced, which was mainly because the aggregation reduced the actual concentration of NPs acting on the microorganisms. Long-term exposure within low Cu NPs (1 mg/L) could also suppress the PN process, and the ammonia removal efficiency decreased to 44.8% from 91%. The ammonia-oxidizing bacteria was more severe to the Cu NPs than nitrite-oxidizing bacteria. After the long-term exposure, the copper and extracellular polymeric substance in sludge both increased, and then decreased when no Cu NPs was added to the PN system anymore. Cu NPs performed a significant effect on microbial activity, nitrogen removal ability and sludge property.