厌氧反应时间对反硝化聚磷功效及微生物种群的影响

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90,120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90 min系统合成的聚羟基烷酸酯(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120 min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(FNA)的积累,这是导致系统脱氮除磷效率降低的主要原因.

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

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.