无排泥条件下HRT对膜生物反应器硝化性能的影响及其生物群落结构分析

以无机氨氮废水(NH+4 N,500mg·L-1)为处理对象,在不排泥条件下逐渐缩短膜生物反应器的水力停留时间(HRT,30h～5h),连续运行260d.在反应器内的氨氮容积负荷和污泥负荷分别为1 2kg·(d·L)-1和2 13kg·kg-1·d-1时,氨氮去除率达98 2%以上.当HRT减少至7h时开始出现NH+4 N和NO-2 N的积累.尽管反应器内MLSS随着运行时间的延长在逐步上升,氨氧化菌(AOB)和亚硝酸氧化菌(NOB)的数量分别从HRT10h和15h起开始下降.16SrDNA聚合酶链式反应结合变性梯度凝胶电泳(PCR DGGE)的分析发现反应器内生物多样性随着运行时间的延长而增加,测序结果表明进行氨氧化作用的主要是亚硝化单胞菌属(Nitrosomonassp.),进行亚硝酸氧化的主要是硝化螺菌属(Nitrospirasp.).尽管反应器只进行无机氨氮配水,仍存在大量的异养菌,估计其生长是以胞外分泌产物和细胞裂解产物为基质.

The influence of HRT on nitrification performance and microbial community changes of MBR under the condition of no sludge discharge

Amembrane bio-reactor had been used to treat inorganic ammoniac wastewater (NH⁺₄-N 500mg·L^-1) for 260 days under decreasing HRTwithout discharge of excess sludge. Under the conditions of the NH⁺₄-Nvolume load at 1.2kg (d·L)^-1 and the NH⁺₄-Nsludge load at 2.13kg·kg^-1·d^-1, the removal rate reached 98.2%. The accumulation of the ammonium and the nitrite appeared when hydraulic retention time (HRT) decreased to 7h. Although MLSSin the bio-reactor gradually increased from 4500mg·L^-1 to 11500mg·L^-1 with the time of the operation, the number of the ammonia-oxidizing bacteria and the nitrite-oxidizing bacteria decreased from 10h HRTand 15h HRTrespectively. The variation of the bacterial diversity was monitored by PCR-amplified 16SrDNA and denaturing gradient gel electrophoresis (DGGE) analysis of the resultant PCRproducts. The profiles of DGGEindicated the increase of the biodiversity through the operation. And the change of the band density showed that the predominant population altered at various conditons. The sequences revealed that Nitrosomonas sp. was the predominant species for ammonia oxidation; Nitrospira sp. was the predominant species to oxidize nitrit. Many heterotraulic bacteria coexisted with nitrifiers even though the reactor was only fed in ammonium inorganic wastewater. It is estimated that the heterotrophic bacteria were responsible for the decomposition of the dead cells and EPS.