铜离子的持续负荷对活性污泥生物硝化活性的影响

重金属对生物硝化的抑制是困扰很多污水处理厂脱氮效果的难题.本文采用间歇式活性污泥反应器(SBR),研究了模拟废水中不同浓度的Cu2+持续抑制及负荷停止后硝化效率、硝化细菌活性和Cu分布的变化.结果表明,硝化活性易受Cu2+的影响,抑制程度随着Cu2+浓度的增大和施加持续Cu2+负荷的运行周期的延长而提高,当活性污泥内、外吸附Cu的总量达(14.0±1.0)mg·g-1(以MLSS计)时,氨氮去除率降至26.5%±4.0%.Cu2+对氨氧化细菌(AOB)的抑制作用大于亚硝酸盐氧化细菌(NOB).在Cu2+负荷为10和20 mg·L-1的体系中,NOB可以全部或部分被驯化而适应含铜废水.恢复阶段,AOB和NOB的活性完全或部分恢复,恢复速率和程度随抑制期Cu2+投加浓度的增加而降低.反应体系内Cu主要分布在细胞内部和表面,且不易解析,硝化抑制率与溶解的Cu2+浓度呈负相关性.

Influence of Cu2+ sustained loads on bio-nitrification of activated sludge

The inhibition on microbial nitrification by heavy metal is a common problem in many wastewater treatment plants. In this work, the effects of different Cu²⁺ concentrations on microbial nitrification efficiency, microbial nitrifying activity and distribution of Cu in sludge solution were investigated through sustained load tests in sequencing batch reactors (SBRs). The results show that the inhibition effects of Cu²⁺ on the ammonia nitrogen removal became significant with the loading concentration of Cu²⁺ and running cycle. The inhibition effect of Cu²⁺ on ammonia-oxidizing bacteria was greater than that on nitrite-oxidizing bacteria. When the accumulation amount of Cu inside and outside the sludge was up to (14.0±1.0) mg · g^-1, the ammonia nitrogen removal rate dropped to 26.5%±4.0%. In the inhibition period, nitrite-oxidizing bacteria could partly or entirely adapt to the presence of Cu²⁺ in 10 and 20 mg · L^-1 Cu²⁺ systems. After a period of recovery, the activities of nitrifying bacteria and nitrification efficiency could partly or entirely recover. Cu was mainly accumulated inside or outside the cells of activated sludge. The adsorbed Cu was hard to be released from activated sludge. The nitrification inhibition rate was negative correlated to the concentration of soluble Cu.