高浓度消毒剂对活性污泥系统中微生物的影响

针对污水厂活性污泥易于发生丝状菌污泥膨胀问题,以西安市第二污水处理厂活性污泥为研究对象,在次氯酸钠投加量为15 mg/L的条件下,探索高浓度消毒剂对活性污泥中微生物的杀灭效果以及对胞外聚合物(EPS)含量和不同类型微生物活性的影响。结果表明,高浓度次氯酸钠能有效杀灭丝状菌,从而控制污泥的丝状膨胀现象,但在杀灭丝状菌的同时也会影响菌胶团絮体内的部分微生物,且对不同微生物的杀灭效果不同,亚硝酸盐氧化菌(NOB)是最易被杀灭的类型。当次氯酸钠投加量为15 mg/L时,反应3 h后污泥胞外聚合物总含量降低了15. 48%,硝化活性丧失殆尽且再未恢复,反硝化活性下降明显;恢复7 d后,絮体内部微生物可以得到有效恢复,而丝状菌大多依然处于死亡状态,EPS总含量继续下降。总之,高浓度消毒剂作用于活性污泥后,可以达到控制丝状菌的目的,但是污泥的硝化和反硝化活性也受到了影响。

Effect of High Concentration Disinfectant on Microorganisms in Activated Sludge System

Aiming at the problem of filamentous sludge bulking in activated sludge system of a wastewater treatment plant(WWTP),effects of high concentration disinfectant on livability,extracellular polymer substances(EPS) content and activity of different microorganisms in activated sludge were explored. The activated sludge was from No. 2 WWTP in Xi’an,and the dosage of sodium hypochlorite was 15 mg/L. The high concentration sodium hypochlorite could effectively reduce the number of filamentous bacteria and further inhibit the filamentous bulking of activated sludge. In addition,parts of the inner microorganisms in the flocs were also affected along with the sterilization of the filamentous bacteria. The cell livability of different microorganisms was different,and the most vulnerable species was nitrite oxidizing bacteria(NOB). When the dosage of sodium hypochlorite was 15 mg/L,the total content of sludge extracellular polymer substances decreased by 15. 48% after 3 hours of reaction,the nitrification activity was completely lost and never recovered,and the denitrification activity decreased significantly. After recovery for 7 days,the activity of the inner microorganisms could be effectively recovered,while most of the filamentous bacteria were still dead,and the total EPS content decreased continuously. In a word,the growth of filamentous bacteria could be inhibited after the action of high concentration disinfectant on activated sludge,but the nitrification and denitrification activities of sludge were also affected.