亚硝酸盐对聚磷菌好氧摄磷的影响研究

利用批量试验研究了不同浓度的亚硝酸盐对聚磷菌好氧摄磷过程的影响,以及在含盐废水硝化过程中亚硝酸盐的累积对聚磷菌好氧摄磷的影响.试验结果表明:亚硝态氮浓度为4 mg/L时,对聚磷菌摄磷有抑制作用,其对摄磷速率的抑制系数为0.08;亚硝态氮浓度为15 mg/L时,对聚磷菌摄磷产生明显的抑制,抑制系数增加到0.61.亚硝酸盐对聚磷菌的抑制作用主要与亚硝酸有关.本研究中亚硝酸浓度在0.000 2 mg/L以上时即对聚磷菌产生较强的抑制作用.亚硝酸盐对聚磷菌的抑制作用只是在亚硝酸盐存在的条件下才发生,一旦亚硝酸盐消失,对聚磷菌的抑制作用即可解除.含盐废水硝化过程中,在好氧反应开始1～2 h内,由于亚硝态氮浓度低,其对聚磷菌摄磷抑制作用小.随着亚硝态氮的逐步累积,亚硝态氮浓度达到8～9mg/L以上时,其对聚磷菌摄磷的抑制作用逐渐增强.进水氨氮浓度高时,好氧反应过程中pH值较低,会导致亚硝酸浓度增高,致使磷酸根的吸收量减少.

Effect of Nitrite on Aerobic Phosphate Uptake by Phosphate Accumulating Organisms

Effect of nitrite at various concentration levels on aerobic phosphate uptake was investigated through a series of batch experiments. Furthermore, the effect of nitrite accumulated in the process of nitrification on aerobic phosphate uptake was studied in saline wastewater treatment. The results show that NO₂-N concentration of 4 mg/L inhibits aerobic phosphate uptake by phosphate accumulating organisms (PAO) and phosphate uptake rate decreases 8%. Exposure to higher nitrite concentration levels inhibits aerobic phosphate uptake severely. At NO₂--N concentration of 15 mg/L, phosphate uptake rate decreases 61%. The toxic effect of nitrite is presumed to be linked with free nitrous acid (FNA). Significant inhibition on aerobic phosphate uptake appeared at 0.0002 mg/L of FNA concentration. The inhibiting effect of nitrite is found to occur only when nitrite is present. The ability of accumulating phosphate resumes after nitrite is no longer present. During the process of nitrification of saline wastewater, the inhibition of nitrite on aerobic phosphate uptake is slight at the initial 1~2 h due to low nitrite accumulation. With the build-up of nitrite (up to about 8 to 9 mg NO₂--N/L), the inhibiting effect of nitrite increases gradually. It is found that higher ammonium concentration causes lower pH value and higher FNA concentration, which could decrease the amount of phosphate uptake.