Side-stream Phosphorous Recovery Sequencing Batch Reactor(SBR)System was established by introducing a side-stream phosphorus(P)recovery unit to the existing SBR system.Duo to the well performance on P removal and P recovery,it has attracted extensive attention.However,it is inevitable to bring negative impacts on the mainstream biological P removal system by introducing the side stream P recovery unit.For the stable operation of the side-stream P recovery-SBR system,it is important to deeply study the changes of phosphate metabolism processes in the mainstream system.Therefore,this study used model to quantitatively analyze the phosphate metabolism processes of the side-stream P recovery-SBR system based on experimental researches,and used model to quantitatively regulate the running of side-stream P recovery-SBR.This subject explored the impacts of side-stream P recovery operation on the effluent quality,the secretion of extracellular polymers(EPS),the changes of key functions bacteria.The results showed that the removal of COD and ammonia nitrogen were slightly affected by introducing side-stream P recovery operation,while the removal of phosphate on recovery phase was obviously improved.The secretion of EPS was promoted and the phosphate contents in per EPS was reduced by side-stream operation.When the side-stream ratio was 30%,60%and 90%,the average content of TB-EPS in the recovery period was 2.21,2.31 and 3.08 times higher than that in the initial period,respectively.The side-stream operation caused changes in the microbial community.The increase of diversity and decrease of richness of microbial community could be observed.In addition,the growth of Proteobacteria,phosphorus accumulating bacteria(PAOs)were inhibited by introducing side-stream operation in different degree.While,the growth of glycan bacteria(GAOs)was promoted by side-stream operation in different degree.The abundance of Rhodocyclus(PAOs)decreased from 3.03%,2.86%and 3.01%(initial period)to 0.17%,0.09%and 0.07%(recovery period).The abundance of Dechloromonas(denitrifying PAOs)decreased from 3.46%,3.56%and 3.55%(initial period)to 2.03%,1.91%and 1.33%(recovery period).The abundance of Defluviicoccus(GAOs)increased from 0.02%,0.01%and 0.05%(initial period)to0.37%,0.44%and 0.53%(recovery period).The D-EPS-ASM2d model was established by extending the competition processes of the GAOs and the P removal by double-layer EPS into the traditional activated sludge 2d model(ASM2d).The simulation results of the side-stream P recovery SBR process were compared between the D-EPS-ASM2d model and the ASM2d model using small-scale test data,a better simulation performance of D-EPS-ASM2d than the ASM2d was quantitatively proved by the model simulation efficiency coefficient.The simulation efficiency coefficients of D-EPS-ASM2d for total P were 0.92,0.88,0.80 and 0.98 at side-stream ratios of 0%,30%,60%and 90%,respectively,which was significantly improved compared with ASM2d model(0.69,0.67,0.71 and 0.92).Contribution rate of each phosphate removal unit on phosphate removal process was investigated by D-EPS-ASM2d model.The results showed that with the increase of side-stream volume the phosphate removal rate of EPS was gradually increased.The phosphate removal rate of EPS was 16%with side-stream volume up to 90%.With the increase of COD:P ratio,the proportion of phosphate removal by EPS increased gradually.When COD:P was 10,in mainstream biological P removal system,the proportion of phosphate removal by EPS was up to 23%.In addition,different influent carbon source compositions have little effect on the proportion of phosphate removal in the system.The regulation performances of metabolic rate of cell contents of PAOs and phosphate metabolic rate of XTEPS were quantitative analyzed by metabolic rate equations of D-EPS-ASM2d model.The results showed that the storage rate of PHA and the release rate of phosphate had significant effects on the release of phosphate in anaerobic stage.The storage rate of polyphosphate could regulate the XPPformation process.The regulation effect of the growth and decay rates of GAOs and PAOs on the biomass of GAOs and PAOs was quantitatively analyzed by rate equations.The results showed that the decay rate of PAOs was significantly affected the biomass of PAOs.When it reached 0.13,the biomass fraction of GAOs was greater than PAOs,indicating that GAOs had an advantage in the competition.The operating side-stream ratio of the SBR was quantitatively controlled,according to the rate of phosphate release(RT)and the storage rate of polyphosphate(RS).When the RT value was decreased,the optimal side-stream volume was decrease,implying that the side-stream of anaerobic supernatant should be reduced with the anaerobic P release capacity of PAOs decrease.The optimal side-stream volumes decrease with the decrease of RS,which was used to reduce the further inhibition of aerobic P absorption capacity of biological P removal system.In addition,compared with the low influent COD/P ratio system,the system with high COD/P ratio is more suitable for the side-stream P recovery operation. |