微氧条件下FA、FNA和pH对半短程硝化的影响

Effect of FA, FNA and pH on Partial-nitrification Under Micro-aerobic Conditions

采用微孔曝气与机械搅拌相结合的序批式反应器(SBR),研究了微氧条件(0.3~0.5 mg/L溶解氧)下游离氨(FA)、游离亚硝酸(FNA)的质量浓度和pH对半短程硝化过程的影响。试验结果表明:在温度为(28±2)℃,进水pH值为7.8~8.3,FA的质量浓度为16~120 mg/L时均可实现稳定的半短程硝化,其中,FA的质量浓度为40 mg/L时亚硝酸盐积累率(NAR)最大,为95%.反应过程中发现,随着反应进行,FA浓度下降,FNA浓度上升,有利于抑制亚硝酸盐氧化细菌(NOB)生长,使实验过程中无需额外持续投加NaHCO 3维持恒定pH,可节约NaHCO 3约40%.反应运行94 d,氨氧化速率由40 mg/(L·h)上升到115 mg/(L·h).高通量测序发现,亚硝化单胞菌占比由32%增至39%;当FA的质量浓度高于40 mg/L时会明显降低氨氧化细菌(AOB)的增长速率,导致Nitrospira数量增多。

The sequencing batch reactor(SBR)combined with microporous aeration and mechanical agitation was used to study the effect of free ammonia(FA),free nitrous acid(FNA)and pH on partial-nitrification under micro-oxygen conditions(dissolved oxygen at 0.3~0.5 mg/L).The results show that stable partial-nitrification occurred at temperature of(28±2)℃,pH of 7.8~8.3,with influent FA concentration from 16 to 120 mg/L.The nitrite accumulation rate(NAR)reached the maximum at FA concentration of 40 mg/L,which was 95%.During the reaction,as FA concentration decreased,FNA concentration increased accordingly,which benifited inhibiting the growth of nitrite oxidizing bacteria(NOB).No additional NaHCO 3 was required to maintain constant pH,thus NaHCO 3 was saved by about 40%.After 94 days of operation,the ammoxidation rate in the reactor increased from 40 to 115 mg/(L·h).By high-throughput sequencing technology the proportion of nitrosomonas was found to increase from 32%to 39%.When FA was higher than 40 mg/L,the growth rate of ammonia-oxidizing bacteria(AOB)was significantly reduced,resulting in an increase in the number of Nitrospira.