生物流化床内亚硝酸积累试验

利用下向流生物流化床反应器研究了生物膜在硝化过程中亚硝酸积累现象．结果表明，挂膜后反应器运行初期出现亚硝酸积累，但氨氮去除率仍可达到97％.随着硝酸菌的适应与增殖，出水中硝化产物以硝酸为主．进水氨氮浓度提高至200mg/L以上时，再次出现亚硝酸积累.在144mg/L和222mg/L进水浓度下，水力停留时间缩短到5h以下，则氨氮去除率下降且出水中亚硝酸所占比例明显上升；容积负荷提高到0.95kgNH₄⁺N/（m³·d）后也会如此反应器中DO降低到0．5～1mg/L会造成亚硝酸积累和氨氮去除率下降．硝化菌适应低氧环境后对氨氮的去除率仍能恢复到85％，但亚硝酸仍积累，这时生物膜中亚硝酸菌成为优势菌.本文还对影响亚硝酸积累的不同因素进行了分析．

Experimental on nitrite accumulation in biological fluidized bed

Nitrite accumulation during nitrification in biofilm in down-flow biological fluldized bed reactor was studied.The results showed that at the beginning of operation after inoculation, there was nitrite accumulation, but ammonia-N removal rate was still up to 97%.Wth nitrobacteria acclimating and proliferating, nitrifying product was mainly nitrate.When ammonia-N concentration in influent was up to more than 200mg/L,nitrite accumulated again. Shortening HRT to less than 5h, under 144mg/L and 222mg/L influent concentrations respectively, nitrite percentage in effluent rose obviously with ammonia-N removal rate declining; the same result occurred with enhaning volumetric loading to more than 0.95kg NH4-N/(m3.d). Reducing DO concentration in the reactor to 0.5~1mg/L also resulted in ammonia-N removal rate declining and nitrite accumulation. After nitrifying bacteria adapted to low DO, ammonia-N removal rate rose to 85%; but nitrite accumulated yet and nitrosomonas predominated in biofilm. Factors affecting nitrite accumulation were also analyzed in the paper.