MUCT短程硝化和反硝化除磷系统中Candidatus Accu- mulibacter的代谢活性和菌群结构

采用实现亚硝酸型硝化的MUCT工艺处理低C/N实际生活污水,在短程硝化的基础上实现反硝化除磷.研究短程硝化建立与破坏过程中,亚硝酸盐积累率的变化对系统除磷性能及Candidatus Accumulibacter菌群结构的影响.结果表明:MUCT除磷以反硝化除磷为主,平均反硝化除磷率高达88%.磷去除率与亚硝酸盐积累率具有很好的正相关性.短程硝化阶段磷的平均去除率比全程硝化阶段高30%以上,证明了亚硝酸盐更适合作为低C/N比污水反硝化除磷的电子受体.以多聚磷酸盐激酶基因(ppk1)作为遗传标记,采用实时荧光定量PCR方法考察不同亚硝酸盐积累率下Accumulibacter的丰度、各主要进化分支的菌群结构和相对丰度.当系统处于全程硝化状态时,存在少量以硝酸盐为电子受体的Acc-I型反硝化聚磷菌,低于总Accumulibacter的5%;当系统进入短程硝化状态后,Acc-I逐渐消失.运行期间以亚硝酸盐作为电子受体进行反硝化除磷的Acc-IID始终是优势聚磷菌,达到总Accumulibacter的92%以上,甚至接近100%,保证了亚硝酸型反硝化除磷的稳定运行,亚硝酸盐浓度是影响其丰度变化的重要因素.

Candidatus Accumulibacter metabolic activity and population structure in MUCT process treating domestic wastewater with nitritation and denitrifying phosphorus removal

Nitritation and denitrifying phosphorus (P) removal was achieved in Modified University of Cape Town (MUCT) process treating domestic wastewater with a low C/N ratio. The effect of nitrite accumulation on performance of phosphorus removal and population structure of “Candidatus Accumulibacter” was investigated during nitritation establishment and destruction. Results indicated that P removal was mainly completed by denitrifying P removal of about 88%. The P removal efficiency had a clear correlation with the nitrite accumulation rate. Under nitritation, the P removal was 30% higher than that under complete nitrification, suggesting that nitrite was appropriate to be used as electron acceptor for denitrifying P removal when treating low C/N wastewater. Real time quantitative PCR assays were carried out using poly-P kinase 1 (ppk1) as phylogenetic marker to characterize the abundance of total Accumulibacter and the relative distributions and abundances of the Accumulibacter clades. Under complete nitrification, a very few Acc-I clade below 5% in total Accumulibacter was present using nitrate as electron acceptor. When the reactor transformed into nitritation, Acc-I clade gradually disappeared. The Acc-IID clade using nitrite as electron acceptor for denitrifying P removal was always the dominant Accumulibacter throughout the operational period, with above 92% on average in total Accumulibacter, even up to nearly 100%, which led to stable performance of denitrifying P removal using nitrite as electron acceptor. The nitrite concentrations significantly affected the abundances of Acc-IID clade.