游离亚硝酸(FNA)对A2O污泥菌群结构的影响

Effect of free nitrous acid(FNA) on microorganism community structures of A^2O sludge

为了探究采用游离亚硝酸(FNA)实现连续流A^2O工艺短程硝化的可行性,考察了不同浓度的FNA对氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)的活性影响,研究了通过投加FNA对活性污泥进行预处理后A^2O反应器的运行效果和微生物菌群结构的变化.结果表明,当FNA浓度为1.12mg HNO_2-N/L时,经过3h的缺氧处理,AOB和NOB的活性分别下降了60%和86%,对NOB有一定的选择性抑菌效应,而投加FNA并对活性污泥进行缺氧处理后的A^2O反应器平均出水NH_4^+-N、NO_2^--N和NO_3^--N分别为12.76、1.56和7.82mg/L,亚硝酸盐积累率(NAR)仅为20%左右,并没有实现预期的短程硝化.高通量和定量PCR的结果也表明,投加FNA并进行缺氧处理后活性污泥中AOB的种群丰度由2.05×108copies/g VSS下降到了3.96×105copies/g VSS,导致系统的氨氧化过程受到了较大影响.最终Nitrobacter和Nitrospira丰度降低,Nitrotoga占总序列数的1.66%,是造成系统无法通过FNA预处理实现连续流A^2O工艺短程硝化的原因.

In order to assess the feasibility of achieving nitritation in the anaerobic/anoxic/oxic(A2O)system through the strategy of free nitrous acid(FNA)sludge treament,the activities of ammonium oxidizing bacteria(AOB)and nitrite oxidizing bacteria(NOB)activities was studied.Besides,the variations of nutrient removal performance and microorganism community structures in the A2O reactor after long-term FNA sludge treatment were investigated.Results showed that the activities of AOB and NOB decreased by60%and86%respectively after the sludge subjectd to FNA treatment at1.12mg HNO2-N/L for3h.The average effluent concentrations of NH4+-N,NO2--N and NO3--N in the A2O system were12.76,1.56and7.82mg/L respectively.The nitrite accumulation rate(NAR)was around20%,indicating that nitritation in the A2O system was not achieved by the FNA sludge treament.Furthermore,High-throughput sequencing and qPCR results showed that AOB abundance was greatly decreased from2.05×108copies/gVSS to3.96×105copies/gVSS and the ammonia oxidation process was negatively affected.In addition,Nitrobacter and Nitrospira were also inhibited,while Nitrotoga accounted for1.66%of total sequences,for which the nitritation in the A2O system was not achieved by FNA sludge treatment strategy.