外加微量N2H4下SBR中硝化微生物特性

运行实验室规模单级硝化序批式反应器(SBR),研究长期外加微量N_2H_4(约3 mg·L~(-1))对硝化污泥中功能微生物好氧氨氧化菌(AOB)、亚硝酸盐氧化菌(NOB)的影响.结果表明,外加微量N_2H_4的硝化污泥中,AOB主要属于亚硝化球菌(Nitrosococcu)属和亚硝化单胞菌(Nitrosomonas)属,另有少部分属于亚硝化螺旋菌(Nitrosospira)属,NOB属于硝化杆菌(Nitrobacter)属.外加微量N_2H_4前后,AOB amoA基因拷贝数(以干污泥计)由1.0×10~9copies·g~(-1)减少为2.09×10~4copies·g~(-1),NOB nxrB基因拷贝数由1.28×10~7copies·g~(-1)减少为2.56×10~5copies·g~(-1).AOB对环境因素较NOB相比更为敏感,N_2H_4对硝化微生物的抑制与毒性作用使外加微量N_2H_4的硝化污泥中AOB流失幅度大于NOB,但定量PCR方法无法准确比较N_2H_4对AOB与NOB活性抑制的强弱.长期外加微量N_2H_4破坏硝化微生物活性,使反应器崩溃.因此在没有厌氧氨氧化菌(AnAOB)消耗N_2H_4的亚硝化系统中,企图通过调控外加N_2H_4浓度水平抑制NOB活性,从而进一步洗脱NOB提高脱氮性能可能无法实现.

Characteristics of Nitrobacteria in SBR with Trace N2H4 Addition

A sequencing batch reactor (SBR) was conducted to perform nitrification process. The influence of long-term trace hydrazine (N₂H₄) addition (about 3 mg·L^-1) on ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in nitrifying sludge was investigated. The result indicated that Nitrosococcu, Nitrosomonas and Nitrosospira were related to AOB, and Nitrobacter was related to NOB in nitrifying sludge with N₂H₄ addition, respectively. The estimates of AOB population (in dry sludge) with N₂H₄ addition decreased from 1.0×10⁹ to 2.09×10⁴ copies·g^-1, and those of NOB decreased from 1.28×10⁷ to 2.56×10⁵ copies·g^-1. AOB was more sensitive to environmental factors than NOB, the effect of inhibition and toxicity on nitrobacteria caused more loss of AOB abundances than that of NOB, but quantitative real-time PCR could not determine the inhibition of N₂H₄ on microbial activity of AOB and NOB. The nitrobacteria activity was destroyed with long-term trace N₂H₄ addition, and the reactor collapsed. Consequently, it was possibly unable to inhibit NOB activity by controlling the added N₂H₄ concentration, and further take off NOB in nitrification process for improving nitrogen removal.