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Screening Of High-efficiency Phosphorus Accumulating Bacteria And Its Application In Wastewater Phosphorus Removal

Posted on:2022-09-20Degree:MasterType:Thesis
Country:ChinaCandidate:Y F YueFull Text:PDF
GTID:2480306605469104Subject:Food processing and security
Abstract/Summary:PDF Full Text Request
Phosphorus is one of the main factors causing red tide and algal bloom in water,and reducing the phosphorus content in wastewater is an effective way to prevent the occurrence of eutrophication.Biological phosphorus removal is an economical and sustainable phosphorus removal technology based on the uptake of phosphorus by polyphosphate bacteria(PAOs)in an aerobic process and,in an anaerobic process,the decomposition of polyphosphate and its conversion to phosphorus for release outside the cell,applied to phosphate removal in wastewater treatment plants.The aim of this study was to screen efficient polyphosphate strains,optimize their complex combinations and phosphorus removal conditions,and apply them to synthetic wastewater for biological phosphorus removal,with the following main results.(1)Twenty-three strains of PAOs were isolated from the sediment samples of Taihu Lake using pure culture technique.After 16S r RNA gene identification,these strains were tentatively identified as Fictibacillus,Microbacterium,Bacillus,Gemmobacter,Aeromonas,Exiguobacterium,Janibacter,Lysobacterium and Rhodococcus.The phosphorus removal rates of these strains in the synthetic wastewater were also determined,and four strains with phosphorus removal rates higher than 70%were PAO25(Fictibacillus sp.),PAS23(Microbacterium sp.),PAOS56(Janibacter sp.)and PAO22(Microbacterium sp.),whose phosphorus removal rates were 83.56%,77.2%,70.4%and 83.47%,respectively.(2)The combination of strains PAO25,PAS23,PAOS56 and PAO22 in a dual,triple and quadruple combination yielded the best phosphorus removal effect when PAO25,PAOS56and PAO22 were combined.Single-factor and response surface experiments were used to optimize the phosphorus removal conditions of the compound polyphosphorus bacterial agents.The results indicated that the best phosphorus removal efficiency was achieved when the ratio of 1:1:1(PAO25:PAOS56:PAO22),p H=7,the addition of sodium citrate concentration was 2.48 mg/L,the temperature was 25.1?and the inoculum level was 7.35%,and the phosphorus removal amount was 15.78 mg/L,the phosphorus removal rate was70.60%.(3)The efficient phosphorus accumulating bacterial agents were applied to seven synthetic wastewaters for biological phosphorus removal experiments.The results revealed that the compound polyphosphorus bacterial agent had the best phosphorus removal effect in oil and grease wastewater with 11.90 mg/L;the initial(8 h)phosphorus removal amounts were the largest for dairy wastewater and slaughter and meat processing wastewater with 10.20 mg/L and 8.90 mg/L,respectively,which was higher thanthe other five synthetic wastewaters.Therefore,we continued to study the effect of phosphorus removal by immobilized polyphosphate bacterial agent in dairy wastewater and slaughter and meat processing wastewater,and the results showed that when the carriers was added to these two wastewaters,the phosphorus removal in the“immobilized bacterial agent group”was higher than that in the“free bacterial agent group”,and then the phosphorus removal in the“immobilized bacterial agent group”was still better than that in the“free bacterial agent group”.Even if the new wastewater was replaced and no addition of polyphosphorus compound,a high phosphorus removal efficiency was still achieved,The maximum phosphorus removal amount of the“immobilized bacterial agent group”was 7.81 mg/L and10.49 mg/L at 8 h.This indicates that the semi-soft carriers can adsorb a large amount of bacteria,and the maximum phosphorus removal amount can be achieved quickly without adding the compound polyphosphorus bacterial agent to the wastewater.(4)The phosphorus removal rate of a new strain of NS18~T,obtained by pre-laboratory isolation,was determined to be 20.17%.Combining all physiological,biochemical and genomic analyses,it was concluded that NS18~T represents a new species named Agrococcus sediminis sp.nov.
Keywords/Search Tags:Phosphate accumulating organisms, Screening, Compound polyphosphorus bacterial agent, Characteristics of phosphorus removal, Biological phosphorus removal
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