Influence of Phosphorus Release and Initial Nitrate Concentration on Anoxic Phosphorus Uptake

Abstract

Abstract-Denitrifying phosphorus removal technology has advantage on beneficial for reduction of COD consumption, and the anoxic phosphorus uptake process is the key process. This study was to investigate the effect of the phosphorus release and initial nitrate concentration, which are two important infectors, on the anoxic phosphorus uptake process, by batch two Tests. The results show that the improvement of Prelease/MLSS would increase the amount of nitrogen and phosphorus removal as well as the specific phosphorus uptake rate(PUR),and the relationship between the amount of P release per MLSS was found in this paper. Nitrate would have little impact on the phosphorus uptake rate in anoxic condition if nitrate was adequate as the electron acceptor. Besides, a function formula was fitted to predict the amount of electron acceptor by the amount of P release per MLSS. I. INTRODUCTIONOver the last decades, the discovery of denitrification phosphate accumulating organisms (DPAO) has been extensively reported, These organisms, as conventional poly-P bacteria, could sequester organic substrates under anaerobic condition, Instead, they utilize nitrate or nitrite as electron acceptor to accumulate phosphate [1]- [7]. Moreover, it is widely recognized that both of denitrification and phosphorus release require organism substrates as electron donor, which is a bottle-neck in resent wastewater treatment plants, especially in China with low COD/N ratio. Thus applying DPAOs in the plants has integrated nitrogen and phosphorus removal for COD is utilized simultaneously, which is beneficial for reduction of COD consumption [8], lower aeration requirement [9], and less sludge production [10]. Although many literatures reported the variety of factors that affected anaerobic phosphorus release and organism uptake, such as MLSS , SRT [11], COD/N,COD/P [12], there are few implies that all the factors would have indirectly or directly impact on the P removal efficiency through P release. No matter what had influenced the anaerobic P release, the amount of phosphorus release could be expressed all the factors affecting P removal. Furthermore, the investigation of the amount of P release should eliminate the influence of MLSS on operation of the experiment, which promoted the concept of the amount of P release per MLSS (Prelease/MLSS). Hence in this study we focused on the investigation of the effect of Prelease/MLSS on the phosphate and nitrogen removal, which will benefit for further innovative processes investigation. Furthermore, the validation of the positive role of nitrate in phosphorus uptake under anoxic condition has been highlighted in literatures [13]- [15]. Conclusion that adequate amount of nitrate would ensure the phosphorus uptake performance had been verified [16]. However, it is necessary to investigate the relation of P-uptake rate and the concentration of nitrate. Most importantly, nitrate should be controlled in a range of value to validate its sufficient requirement as electron acceptor under anoxic condition in...