低溶氧下生物流化床内亚硝化过程的选择特性研究

Study on the selection process of nitrification under low dissolved oxygen in biofilm in biological fluidized bed

采用下向流内循环生物流化床反应器 ,在低浓度溶解氧条件下 ,探讨了亚硝化过程的稳定性 .试验结果表明 :在 0 .5～ 1 .0 mg/L溶解氧 ( DO)下 ,DO成为增殖的限制基质 ,可实现亚硝酸的稳定积累 .当进水NH+ 4 -N为 3 0 0 mg/L时 ,出水 NH+ 4 -N小于 2 0 mg/L;在保证氨氮去除率大于 90 %的前提下 ,使出水硝态氮中亚硝酸比例稳定在 80 %以上 .选择过程完成后亚硝酸菌成为生物膜中的优势菌群 .

A down flow biological fluidized bed reactor (DBFB) was used to discuss the stability of nitrification through nitrite under low concentration of dissolved oxygen(DO).The experiment results showed that the nitrite accumulation was stabe by dynamic selection under the limiting substrate of growth (DO).When DO concentration was 0 5～1 0 mg/L and influent NH + 4-N concentration was 300 mg/L,the effluent NH + 4-N concentration was lower than 20 mg/L and its removal efficiency more than 90 %; the effluent NO - 2-N concentration could reach as high as 220～240 mg/L and NO - 2-N /( NO - 2-N + NO - 3-N) was above 80 % stably. The MPN test showed that nitrosomonas dominated in the biofilm after accomplishment of selection under low DO levels.