pH对厌氧-限氧SBR同步脱氮除磷效果及N2O释放的影响

为研究pH对厌氧-限氧SBR同步脱氮除磷效果以及对N_2O释放的影响,接种亚硝化活性污泥,以含乙酸钠、氨氮、磷酸盐的人工配水为基质,通过逐步提高进水COD,在厌氧-限氧(DO 0.3~0.8 mg/L)SBR中成功实现了同步脱氮除磷(SNDPR).反应器稳定期间氮、磷的去除率分别达(76.1±5)%、(98.4±1)%.采用批式实验研究了不同进水pH(6.0、7.0、8.0、9.0)对脱氮除磷效果及N_2O释放的影响.结果表明,pH为9.0时除磷效果最好,除磷率达87.7%,其次为pH为6.0时,除磷率达84.0%;随着pH降低,氨氧化速率呈升高趋势,pH为6.0时单位MLSS氨氧化速率和脱氮率最大,二者分别为3.7 mg/(L·h·g)和83.9%;N_2O释放量随pH的升高而减小,pH为6.0时的释放量是9.0时的3.5倍.综上,pH为6.0时,能获得较高的脱氮除磷效率,但同时会增加N_2O的释放量.

Effect of pH on nutrients removal and nitrous oxide emissions from an anaerobic/oxygen-limited SBR performing simultaneous nitrification, denitrification and phosphorus removal

To research the effect of pH on nutrients removal and nitrous oxide emissions from an anaerobic/oxygen-limited SBR performing simultaneous nitrification, denitrification and phosphorus removal (SNDPR), the SNDPR process was successfully developed in an anaerobic/oxygen-limited (DO concentration of 0.3-0.8 mg/L) lab-scale sequencing batch reactor fed with synthetic wastewater mainly containing acetate, ammonia and phosphorus by inoculating with nitritation sludge. The reactor removed (76.1±5)% and (98.4±1)% of the influent nitrogen and phosphorus, respectively. The effect of initial pH on the performance of SNDPR and nitrous oxide emissions was investigated by batch experiments. The results showed that phosphorus was well removed at pH 9.0 and 6.0, and the removal efficiencies were 87.7% and 84.0%, respectively. The ammonia oxidizing rate increased with the decrease of pH from 9.0 to 6.0, and the maximum ammonia oxidizing rate of 3.7 mg/(Lhg) and nitrogen removal efficiency of 83.9% were gained at pH 6.0. The emission of nitrous oxide decreased with the increase of pH. Specifically, the nitrous oxide emission at pH 6.0 was 3.5 times of that at pH 9.0. This study revealed that the nitrogen and phosphorus could be better removed at pH 6.0, and meanwhile, it could induce more nitrous oxide emissions.