缺氧胁迫影响硝化污泥活性的机理

Mechanism of effect of anoxic stress on nitrification

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、24h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、24h缺氧处理后,污泥平均比氨氧化活性分别从0.894mgN·(gMLSS)-1·h-1降为0.453、0.387mgN·(gMLSS)-1·h-1,下降了46.8%、49.8%;平均比亚硝酸氧化活性也从0.761mgN·(gMLSS)-1·h-1降至0.485、0.459mgN·(gMLSS)-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%(12h)和24%、21%(24h);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。

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 Oh, 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）· 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）·h^ -1, respectively, at a decrease of 36.3% and 39.7%. The 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.