Study On Biological Removal Of Phosphorus From Water

Bacterial strains which could remove phosphorus were isolated from a batchculture and the sludge from Chaohu .After determining the rest quantity ofphosphorus,A,B,C were selected as dominant bacterial strains for its bestphosphorus-accumulating ability to phosphorus.K1,K2 were also selected anotherdominant bacterial strains after ion beam implantation .Effect of temperature andpH,carbon source,C/N,aerobic and anaerobic time were studied.The main resultswere summarized as follows. 1.Nine bacterial strains which could remove phosphorus were isolate from a batchculture and the sludge from Chaohu lake.After determing the quantity ofphosphorus,A,B,C were selected as dominant bacterial strains for its best removalability to phosphorus.Based on the morphological appearances and physiologicalcharacteristics.A,B,C were identified as Pseudomonas.sp. 2.K1,K2 were also selected as another dominant bacterial strains for its higherremoval ability to phosphorus than the other strains after ionbeam implantation.K1,K2 were identified as Pseudomonas.sp.The properties of continual inoculation wasstable. 3.The optimal temperature to five strains was 30℃.The optimal pH to A,K2 was8, it was 7 to B,C and 6 to K1.The optimal time to A,B,C was 2d, it was 3d toK1 and 4d to K2.The optimal OD to A,C,K2 was 0.4 and it was 0.6 to B,K1。 4.The time of maximal phosphorus concentration was 3d to B,K1,K2 and 4dto A,C under aerobic condition.Then the concentration of phosphorus declined in 3dunder anaerobic condition. 5. Under the anaerobic condition ,the removal ability of C,K2 was higher thanthe other single strains.The removal ability of A+B+C was higher than the othermixed strains.There was no significant vary between the single strains and mixedstrains. 6.The optimal carbon source was glucose or soclium acetate.The removal abilityto phosphorus was high with optimal carbon source.The optimal C/N was 3:1 to A,C,K2 and it was 6:1 to B and 5:1 to K2.7.Under the anaerbic and aerobic condition,there was significant vary between thesingle strains and mixed strains.From 8mg/L to 20mg/L of phosphorus,the removalability of C was higher than other single strains,and A+B+C was higher than othermixed strains.The removal ability to phosphorus under the anaerbic and aerobiccondition was higher than it under the anaerbic condition. 8. During the process of phosphorus removal, 20%-30% phosphorus was reservedin strains,the rest phosphorus was converted into the other matter in strains.Themachanism is accord with the machanism of "PAO".Under the anaerobic condition,biological phosphorus accumulating bacteria take up SCFAs and convert them topoly-b-hydroxybutyrate (PHB) as an internal carbon reserve. The energy source forthe uptake of SCFAs and the conversion to PHB is believed to be mainly from thehydrolysis of stored polyphosphate because it is observed that the PO4-P levelincreases significantly in the medium during the anaerobic phase. During the aerobiccondition, the PHB reserve is oxidized to supply carbon and energy for the bio-Pbacteria growth, as well as energy for the re-synthesis of polyphosphate andglycogen.PO₄-P is excessively taken up from the medium during this phase.