包埋氨氧化细菌短程硝化的高效稳定运行

为了提高包埋氨氧化细菌短程硝化的效率,富集培养氨氧化细菌(AOB)并固定化.富集培养阶段采用连续式运行方式,以游离氨(FA)为抑制亚硝酸盐氧化菌(NOB)生长的手段,并通过定时排泥方法使NOB逐渐从系统中淘洗出去.富集培养结束后以聚乙烯醇(PVA)为包埋材料,对筛选培养的氨氧化细菌进行固定化,反应器包埋填充率为8%.采用连续式运行方式,通过逐步增加氨氮负荷的方法提高氨氧化速率.最终在富集培养系统中实现了污泥比氨氧化速率(以NH_4~+-N/VSS计)2.028 g·(g·d)~(-1)的高表达和亚硝酸盐氮90%以上的高积累.通过对污泥富集培养前后细菌群落组成的高通量测序分析,结果表明,培养前原污泥多样性较大,具有硝化作用的Nitrosomonas仅有0.24%,Nitrospira有2.7%.富集培养后的活性污泥多样性明显变小,优势菌种为Nitrosomonas(18%),而Nitrospira仅剩0.02%;包埋固定化后,系统迅速实现了短程硝化,最终短程硝化的速率达到了50 mg·(L·h)~(-1),亚硝酸盐氮积累率稳定在90%以上.

Efficient and Stable Operation of Shortcut Nitrification by Entrapping Ammonia Oxidizing Bacteria

In order to improve the efficiency of shortcut nitrification by entrapping ammonia oxidizing bacteria, the technique of ammonia oxidizing bacteria(AOB) enrichment culture was studied. The continuous operation method was used to inhibit the growth of nitrite-oxidizing bacteria(NOB) by free ammonia, at the same time, the NOB was gradually washed out of the system through the technology of sludge discharge. Polyvinyl alcohol(PVA) was used as the embedding material to immobilize the ammonia oxidizing bacteria after enrichment culture. The embedding rate of the reactor was 8%. The ammonia oxidation rate was increased by improving ammonia nitrogen loading in the continuous operation mode. The results showed that the ammonia oxidation rate(NH₄⁺-N/VSS)was as high as 2.028 g·(g·d)^-1 and the nitrite nitrogen accumulation rate was stabilized at more than 90%. High-throughput sequencing analysis was conducted on the bacterial community composition before and after enrichment culture, and the experimental result indicated that the culture diversity of raw sludge was larger. Nitrosomonas and Nitrospirae, which have nitrification function, accounted for 0.24% and 2.7%, respectively. The diversity of the activated sludge decreased significantly after the enrichment culture, Nitrosomonas(18%) became the dominant bacteria whereas Nitrospira occupied only 0.02%. After he embedding of ammonia oxidizing bacteria, the shortcut nitrification was realized rapidly. Finally, the shortcut nitrification rate reached 50 mg·(L·h)^-1and the nitrite nitrogen accumulation was above 90%.