Research Of Species And Distribution Of Phosphorus And Biological Phosphorus Removal Mechanism In Enhanced Biological Phosphorus Removal(EBPR) System

The realization of the biological phosphate removal relies on one kind of bacteria that are called phosphate accumulating organisms (PAOs)—who has the ability to absorb the phosphate excessively. The phosphate removal capacity of phosphate accumulating organisms (PAOs) and the speciation and distribution of phosphorus in activated sludge using SMT method were investigated in a lab-scale continuous enhanced biological phosphorus removal system (EBPR) with different C/P ratio influent and varied pH. The results were shown as follows:Under the condition of different C/P ratio, EBPR system can achieve good performance of nitrogen and phosphorus removal, the removal rate of COD,TN, NH4+-N, SOP was stable at around89%,75%,95%,88%。 And C/P ratio made little effect on their performance. For the C/P ratio decreased from lOOmgCOD/mg P to43mgCOD/mgP, the phosphorus-released amount and phosphorus-untake amount were increased, the intracellular PHA and Poly-P synthesized and utilized capacities and efficiencies were better, and and synthesized amount of phosphorus and Poly-P by consuming unit PHA of aerobic sludge were raised. With the C/P decreased, denitrifying performance in aerobic zones was improved.Total phosphorus(TP) content of activated sludge in EBPR system was about22.25-37.53mg/g,inorganic phosphorus (IP) content was about14.56～24.68mg/g, which is the main existing form. non apatite inorganic phosphorus (NAIP) amount was9.87～16.79mg/g,which is the main speciation. In the course of anaerobic to aerobic reaction, the PAOs transferred phosphorus of wastewater into sludge through biologic action and absorption, total phosphorus (TP) and inorganic phosphorus (IP) amount was higher under smaller C/P condition and the percentage of IP and OP remained stable. In IP, with a certain range, with decreasing C/P ratio, the percentage of NAIP declined, there is a small part of NAIP converted to AP forms.In the static experiment, anaerobic released phosphorus showed a good linear relationship with the degradation amount of COD; unit sludge phosphorus released rate and phosphorus uptake rate were11.3mg/(gMLSS h) and5.75mg/(g MLSS h); The Synthesis and degradation of PHA were118.7mg/g and117.3mg/g respectively.,and the counterpart PHB were100.9mg/g and99.7mg/g respectively, accounting for85%and84.9%of PHA. The PHB/PHV ratio reflected qualitatively that PAOs gets a significant advantage in the competition between PAOs and GAOs. While changes in phosphorus forms can be qualitatively inferred that not all of phosphate were stored in the PAOs in the form of poly-phosphate, but also part of phosphate absorbed by EPS in the form of weakly adsorbed phosphorus.Change influent pH, total phosphorus and phosphorus forms changed significantly the phosphorus content of sludge under alkaline environment was slightly above neutral environment sludge system, and neutral environment sludge phosphorus content was significantly higher than acidic environment.Under the condition of pH=6, the pollutant removal efficiency of system was worse and the anaerobic phosphorus release capacity of PAOs was inhibited significantly. The TP and IP’s amount TP and IP amount increased in aerobic phase was higher under higher pH amount,the efficiency of biological phosphorus removal and capacity of enriching phosphorus of aerobic sludge were better as well.