Screening Of Phosphate-accumulating Organisms And Study On Removing Phosphate Characteristic In Sewage Water

Recently, eutrophication of surface water was more and more serious in our country, which has destroyed the balance of aquatic ecosystem, polluted drinking water, restricted development of industry and agriculture. Some researches indicated that phosphate was the key factor of eutrophication of surface water, so it was more important to remove phosphate from surface water in order to prevent eutrophication.Phosphate-accumulating organisms(PAOs) were a kind of particular facultative bacteria, they could release phosphate in anaerobic condition, but take in phosphate in aerobic condition, and store phosphate in cell with Poly-P. Therefore, phosphorus concentration of strains was several times than generic strains. PAOs were applicated to biological removal of phosphorus widely. It was a new technology of sewage disposal with PAOs, and biological phosphorus removal has been studied proverbially because of good effect,low cost, energy-saving and non-secondary pollutant.But, up to now, few PAOs were separated,and researches were insufficient on mechanism and application of them.So the aims of this experimentation were isolating effective PAOs, studing accumulating phosphate characteristic, and treating with phosphorus pollution in simulant eutrophication water, which could provide some academic basis and excellent strains for biological removal of phosphorus. Some results showed that:1.Seven PAOs were isolated by microbial method(blue- and white-colored colonies, Toluidine Blue staining method) and molecular biology (16SrDNA sequence analysis) from activated sludge of Beijing Gaobeidian Sewage Factory, sewage water of Beijing Qinghe and Weishan Town of Shandong Province, which were QH-6(Caulobacter sp.),CH-16③(Pseudomonas sp.),CH-16②(Pseudomonas sp.),WN-7(Thermomonas sp.),QH-2(Sphingobacterium),小-15(Comamonas sp.),AO-2(Alicycliphilus).2. Capability of accumulating phosphate of them was studied, phosphorus removal rate of CH-16②,CH-16③,AO-2 respectively reached 81.83%,78.67%,81.05%,68.44%,66.68%,67.59%,54.41%,41.79%,48.92% on the condition of 2mg/L,5mg/L,10mg/L.Four important factors, OD, pH value, phosphorus removal ratios and capability of accumulating phosphate of CH-16②,CH-16③,AO-2,were studied to evaluate their change by time. Results show that OD and pH value kept increasing,and phosphorus concentration kept decreasing by time.At around 12h,OD reached the highest,but phosphorus concentration was the lowest.Phosphorus concentration in the three strains reached about 10% of their weight,and removal speed of phosphorus reached 0.4625 mg/(L·h),0.4938 mg/(L·h),0.4810 mg/(L·h)respectively,indicating that they all had a high capability of accumulating phosphate.3.According to the inhibited infunction between microorganism and test of phosphorus removal rate,a best combination microorganism including tow Pseudomonas alcaligenes strains,one Sphingobacterium multivolume strain and one Thermomonas strain were made sure。4. Simulant eutrophication water was treated with A/O process.At the same time, effect of biological phosphorus removal was studied using bio-film carriers,immobilization in Sodium Alginate and dissociative phosphate-accumulating organisms.Two weeks later,phosphorus concentration of three treatments all declined. Among them, effect of treatment one was the best,phosphorus concentration in the simulant eutrophication water declined from 3.09 mg/L to 2.02 mg/L, phosphorus removal rate reached 34.63%.In the whole examination,the pH value of each treatment keep 7.3～7.6.But in the sequel,phosphorus concentration of each treatment show a increased trend,and phosphorus removal rate declined.Therefore,the valid period of phosphate-accumulating organisms was 14 days.