Induction of enhanced biological phosphorus removal under permanent aerobic environment and its influencing factors

This paper is aimed at introducing our investigation and analysis of the induction of enhanced biological phosphorus removal( EBPR) under permanent aerobic environment and its influencing factors. For our study purpose,we have taken our sample inoculated sludge from an oxidation ditch,and then fed a typical substrate of acetate to a sequencing batch reactor( SBR). The experiment results we have gained show that the efficient phosphorous removal under the above said continuous aerobic condition can be achieved on the 9th day,when the SBR operation mode turns from the alternating anaerobic and aerobic zones to the permanent aerobic environment. The phosphorus removal efficiency we have managed to achieve can be as high as over 90%,with the phosphorus mass concentration in the effluent being less than 0. 5 mg / L. The actual variations of the concentration of chemical oxygen demand( COD),the phosphorus in the sewage,poly-β-hydroxybutyrate( PHB) and the polyphosphate in the sludge prove that it is possible to divide the aerobic time into two phases: the feast phase and the famine phase. In the feast phase,the consumption of acetate tends to be linked with the release of phosphorus and storage of PHB. When the acetate was depleted,the famine phase would start,which is related to the uptake of phosphorus and the growth of biomass and involves the degradation of PHB.However,the variation of the substrate concentrations in the said two phases seems to be analogous to the anaerobic / aerobic periods,just as a kind of adjustment of phosphate accumulating organism( PAOs)metabolic pathway that can be made fit for the new environment.Further studies of the phosphorus removal characteristics under different aerobic time lengths and standing time indicate that it is only possible to increase the efficiency of phosphorus removal by prolonging the aerobic time over 3 hours and the maintaining time over 2. 5hours, though the removal efficiency of the permanent aerobic process may still remain unstable. Besides,the concentration of phosphorus in the effluent has a tendency to rise with the time,while the removal efficiency can be recovered by changing the mode of SBR to alternation of anaerobic and aerobic again. Thus,it can be concluded that the alternating anaerobic / aerobic zones tends to be the motive power to maintain the high phosphorus removal efficiency in spite of the fact that the fluctuation of the removal efficiency is likely to be various with the operation mode.