基于HCO_(3)^(-)/N控制部分亚硝化及影响因素

Achievement and influencing factors of partial nitritation based on HCO_(3)^(-)/N

部分亚硝化的稳定控制是基于厌氧氨氧化的两段式自养脱氮高效运行的关键。在好氧条件下(DO>1 mg/L),通过控制HCO_(3)^(-)与NH^(4+)的摩尔比,在SBR系统实现了高氨废水部分亚硝化的启动与长期稳定运行,出水NO_(2)^(-)-N/NH^(4+)-N为1.09±0.08。在此基础上,通过批式试验考察了HCO_(3)^(-)/N及pH对部分亚硝化的影响。结果发现,随着进水HCO_(3)^(-)/N由0.5∶1升高为1∶1,1.5∶1和2∶1,氨氮转化率由33.62%增加至57.41%,100%和100%。在控制HCO_(3)^(-)/N为1∶1前提下,随着pH由7升至8和9时,氨氮转化率由56.89%升高至61.32%和100%,平均氨氧化速率分别达0.39,0.42,0.49 mg N/(g MLSS·min)。结果表明,HCO_(3)^(-)/N和pH通过影响游离氨和游离亚硝酸的浓度同步影响着氨氧化速率、转化率和亚硝酸盐氧化,HCO_(3)^(-)/N为1∶1及pH=8是实现高氨废水部分亚硝化稳定运行的重要参数。

The stable operation of partial nitritation(PN)is the key to obtain a high nitrogen removal efficiency of the two-step partial nitritation-anammox process.By controlling the molar ratio of HCO_(3)^(-)to NH^(4+),start-up and stable operation of partial nitritation treating high ammonium wastewater were achieved in a sequencing batch reactor(SBR)under aerobic conditions,generating an NO_(2)^(-)N/NH^(4+)molar ratio of around 1.09±0.08 in the effluent.Thereafter,the effects of different HCO_(3)^(-)/N and pH on partial nitritation were investigated through batch experiments.With the increasing ratios of HCO_(3)^(-)to NH^(4+)in the influent from 0.5∶1,1∶1,1.5∶1 tO_(2)∶1,33.62%,57.41%,100%and 100%of ammonium was converted to nitrite.When the ratio of HCO_(3)^(-)to NH^(4+)was controlled at 1∶1,together with the pH increased from 7 to 8 and 9,the conversion efficiency of ammonia nitrogen increased from 56.89%,61.32%to 100%,and the ammonia oxidation rate was 0.39,0.42 and 0.49 mg N/(g MLSS·min),respectively.Both HCO_(3)^(-)/N and pH affect ammonia oxidation rate,conversion efficiency and nitrite oxidation simultaneously by affecting the concentration of free ammonia(FA)and free nitrous acid(FNA).Therefore,the HCO_(3)^(-)/N of 1∶1 as well as pH of 8 were found to be the essential parameters for stable operation of partial nitritation.