Enrichment of Denitrifying Phosphate-accumulating Organisms in Nitrogen and Phosphorus Removal Process

Abstract

In this paper, a review on the mechanism of denitrifying phosphorus removal and the enrichment of denitrifying phosphorus-accumulating organisms in the process of nitrogen and phosphorus removal, such as A 2 /O and SBR, were presented, as well as the influence factors of enrichment were also carried out. And finally, the outlook of denitrifying phosphorus removal process for future research was suggested. Conventional biological treatment process can effectively reduce BOD5 and SS of inflow, but the removal efficiencies of nitrogen and phosphorus in wastewater are not effective, which cause that a large amount of sewage containing nitrogen and phosphorus directly discharge into water body. Therefore, the nitrogen and phosphorus pollution is the primary cause for water entrophication. Although the government put forward more and more strictly requirements for sewage discharge, it is difficult to remove nitrogen and phosphorus efficiently for the conventional nitrogen and phosphorus removal process, because of various reasons, such as carbon-nitrogen ratio in the city sewage. So it is necessary to develop more stable, economical and efficient process for nitrogen and phosphorus removal. Denitrifying phosphorus removal process is to complete domestication and enrichment of denitrifying phosphate-accumulating organisms (DNPAOs) by using anaerobic/anoxic alternate environment instead of the traditional anaerobic/aerobic environment. DNPAOs can use NO3 - as electron acceptor in denitrifying phosphorus removal system, meanwhile through their metabolism complete excess phosphorus uptake and denitrification process at the same time to achieve the dual purpose of nitrogen and phosphorus removal. Application of denitrifying phosphorus removal process for treatment of municipal wastewater can not only save aeration quantity, but also reduce the amount of residual sludge. And it also can cut down investment and operation costs. In recent years, many scholars did a number of researches on denitrifying phosphorus removal technology. Due to the varying techniques, enrichment mode and denitrifying phosphorus removal degree, the conclusion was not entirely consistent.