厌氧反应时间对反硝化聚磷功效及微生物种群的影响

Impact of anaerobic reaction time on denitrifying phosphorus removal performance and microbial structure dynamics

摘要:

对于反硝化除磷系统来说，厌氧代谢开展的充分与否直接决定后续缺氧阶段的反硝化脱氮和除磷效果。因此，厌氧反应时间作为决定厌氧代谢开展程度的主要工况也成为反硝化除磷工艺设计需重点考虑的因素之一。本试验采用厌氧/缺氧/好氧序批式反应器（An/A/O-SBR），考察了不同厌氧反应时间（分别为90min，120min和150min）长期运行条件下的反硝化除磷效果，并利用荧光原位杂交（FISH）技术分析了系统内微生物种群的结构变化。结果发现，厌氧反应时间为90min系统合成的PHA量最高，脱氮和除磷平均去除率分别达到92%和93%，聚磷菌占总菌的58±2.3%；厌氧反应时间为120min的系统脱氮和除磷平均去除率分别达到97%和73%，聚磷菌占总菌的50±2.2%。而厌氧反应时间为150min的系统合成PHA最低，平均脱氮率仅为79%，聚磷菌数量也减少至45±2.7%。厌氧反应时间过长致使PHA含量水平下降，继而发生游离亚硝酸（free nitrous acid，FNA）的积累，是导致系统脱氮除磷效率降低的主要原因。

Abstract:

For denitrifying phosphorus removal systems, whether the anaerobic metabolism conducted successfully directly determines the denitrification and P uptake performance in the subsequent anoxic phase. Therefore, anaerobic reaction time (AnRT) has become a key parameter when designing denitrifying phosphorus removal process. The long-term impact of the different anaerobic reaction times (i.e. 90, 120 and 150 min) on denitrifying phosphorus removal performance was conducted in an anaerobic/anoxic/aerobic (An/A/O) sequencing batch reactor (SBR). Also, the microbial structure dynamics were analyzed by fluorescence in situ hybridization (FISH) techniques. The results showed that the system with the shortest anaerobic time of 90 min produced the highest amount of PHA during anaerobic phases, and the average nitrogen and phosphorus removal efficiencies maintained at 92% and 93%, respectively; also, the corresponding phosphorus accumulating organisms (PAOs) was accounted for 58±2.3% of the total biomass. The average nitrogen and phosphorus removal efficiencies of the system with the anaerobic time of 120 min maintained at 97% and 73%, respectively; and the corresponding PAOs was accounted for 50±2.3% of the total biomass. The lowest anaerobically synthesized PHA was occurred in the system with the anaerobic reaction time of 150 min, accompanied by the poorest N removal efficiency of 79% (mean value); also, the PAOs percentage was reduced to 45±2.7%. It appears that a too long anaerobic reaction time had led to a decreased level of the PHA content and increased free nitrous acid (FNA) accumulation, which ultimately resulted in the reduced nitrogen and phosphorus removal efficiencies.