Research On The Isolation And Microbial Characteristic Of Phosphorus Accumulation Organism

Phosphorus removal is very important to prevent eutrophication in water system. Biological phosphorus removal is a most wildly applied method in the world. Phosphorus Accumulation Organism (PAO) is a series of activated-sludge bacteria with high levels of phosphorus-accumulating activity. Thus, it is an interesting model organism to study biological phosphorus removal. Two laboratory-scale sequencing batch reactors (SBRs) were operated for biological phosphorus removal in alternating anaerobic-aerobic or alternating anaerobic-anoxic modes, respectively. PAOs were enriched in the anaerobic-aerobic SBR and denitrifying PAOs (DPAOs) were enriched in the anaerobic- anoxic SBR. 20 strains of bacteria have been isolated from two sets of SBR which are steady running by traditional way of cultivating. After studying the bionomics and characteristic, the experimental results show that:1. Phosphate release and uptake activity is remarkable in A/O SBR by 14 days alternating anaerobic-aerobic mode. Under the condition of COD=180mg/L, PO₄^3--P=10mg/L, NH₄⁺-N=30mg/L, both removal rate of phosphate and ammonium is higher than 95%.2. Phosphate release and uptake activity is also remarkable in A/A SBR by 25 days alternating anaerobic- anoxic mode. Under the condition of COD=180mg/L, PO₄^3--P=20mg/L, NO₃^--N=25mg/L, both removal rate of phosphate and nitrate is also higher than 95%.3. Twenty strains of bacteria have been isolated from two sets of SBR and five of them have been confirmed as phosphorus accumulating bacteria by way of PHB straining, poly-P straining and analysis of phosphate uptake and release. 3 strains of them are aerobic PAOs and 2 are DPAOs. 4. Phosphate uptake and release of the aerobic PAOs are better than DPAOs on the whole. The best one is SYO-8.5. SYO-1 grow fast on the culture medium, its colony is white, translucent, circular, glossy, with the diameter 1-4mm. The bacteria are Gram-negative rods, the best producing time is the third day, the most suitable pH is 7, and temperature is 30℃. SYO-2 grow less fast on the culture medium, its colony is yellow, translucent, circular, glossy, with the diameter 1-2mm. They are Gram- positive rods, the best producing time is the fourth day, the most suitable pH is 6, and temperature is 25℃. SYO-8 grow slowly on the culture medium, its colony is hoar, opaque, erose, coarse, with the diameter 1-4mm. They are Gram- positive coccus, the best producing time is the fifth day, the most suitable pH is 8, and temperature is 35℃. SYA-2 grow less fast on the culture medium, its colony is white, opaque, circular, glossy, with the diameter 1-2mm. They are Gram- negative rods, the best producing time is the third day, the most suitable pH is 7, and temperature is 30℃. SYA-5 grow slowly on the culture medium, its colony is nacarat, opaque, circular, glossy, with the diameter 1-2mm. They are Gram- negative rods, the best producing time is the second day, the most suitable pH is 8, and temperature is 35℃.