缺氧胁迫影响硝化污泥活性的机理

硝化过程是废水生物脱氮的关键环节。为了研究缺氧胁迫对硝化活性的影响及其机理，采用分批培养法分别测定了经0、12、24 h缺氧滞留处理的污泥硝化活性、过氧化氢酶活性和过氧化物酶活性，以及这些硝化污泥抗氧毒（过氧化氢）性能。经过12、24 h缺氧处理后，污泥平均比氨氧化活性分别从0.894 mg N·(g MLSS)^-1·h^-1降为0.453、0.387 mg N·(g MLSS)^-1·h^-1，下降了46.8％、49.8％，平均比亚硝酸氧化活性也从0.761 mg N·(g MLSS)^-1·h^-1降至0.485、0.459 mg N·(g MLSS)^-1·h^-1，下降了36.3％、39.7％。试验结果证明，缺氧胁迫可降低污泥硝化活性，缺氧胁迫时间越长，硝化活性降幅越大，缺氧胁迫对氨氧化的影响大于亚硝酸氧化。缺氧胁迫可抑制硝化污泥的抗氧化酶活性，POD、CAT活性分别下降了10％、17％（12 h）和24％、21％（24 h），缺氧胁迫时间越长，抗氧化酶活性越低。缺氧胁迫可削弱硝化细菌的抗氧毒能力，引起硝化活性降低。

Mechanism of effect of anoxic stress on nitrification

Nitrification is a crucial step in the biological removal of nitrogen from wastewaterTo investigate the mechanism of the effect of anoxic stress on nitrification, nitrification activity, catalase activity, peroxidase activity and the H₂O₂ resistance of nitrifying activated sludge were determined after 0h, 12h, and 24h exposure to anoxic environmentAfter 12h and 24h anoxic treatment, the average specific ammonia oxidation rate decreased from 0894 mg N·(g MLSS)^-1·h^-1 to 0.453, 0.387 mg N·(g MLSS)^-1·h^-1, respectively, at a decrease of 46.8% and 49.8%， meanwhile, average specific nitrite oxidation rate decreased from 0761 mg N·(g MLSS)^-1·h^-1 to 0.485, 0.459 mg N·(g MLSS)^-1·h^-1， respectively, at a decrease of 36.3% and 39.7%he results showed that anoxic stress could decrease nitrification activity of nitrifying activated sludgeThe longer the duration of anoxic stress, the lower the nitrification activityAmmonia oxidation activity was inhibited more seriously than nitrite oxidation activityAnoxic stress could influence anti oxidative enzyme activityPOD and CAT activities decreased by 10%, 17% for 12h anoxic treatment, 24％, 21％ for 24h anoxic treatmentThe longer the nitrifying activated sludge exposed to anoxic environment, the lower the anti oxidative enzyme activityAnoxic stress could weaken the toxicity resistance of reactive oxygen, leading to the decrease of nitrification rate.