Denitrifying enhanced biological phosphorus removal from municipal wastewater under anaerobic/anoxic conditions

Abstract

Conventional enhanced biological phosphorus removal is based on anaerobic phosphorus release and aerobic phosphorus uptake, which requires more energy supply and sludge production. Thus, there are growing concerns about effective phosphorus removal from wastewater with lower energy requirement. The aim of this study was to achieve enriched sludge of denitrifying phosphorus accumulating organisms with anaerobic/anoxic conditions, especially with NO₂ -N, and explore the possibility of anoxic EBPR process with NO₂ -N as the sole electron acceptor in anaerobic/anoxic process. This study included an extensive literature review, laboratory works involving continuous operation of biological reactors and sample analysis for data collection, data analysis and process simulation for practical phosphorus removal, to address the research questions. The results suggested that long-period continuous NO₂ -N dosing in anoxic phase could induce faster enrichment of denitrifying phosphorus accumulating organisms and more efficient phosphorus removal than NO₃ -N at ambient temperature, without toxic inhibition of nitrite. The ratio of NO₃ -N to NO₂-N was accorded to the amount of electron transfer of them, to remove the same amount of phosphorus. Dechloromonas is the functional microbial group in anoxic phosphorus uptake in both NO₂ -N and NO₃ -N based anaerobic/anoxic systems. It was concluded that the complete phosphorus removal could be achieved with NO₂ -N as the sole electron acceptor in anaerobic/anoxic reactors, with enriched denitrifying phosphorus accumulating organisms.

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ORCID for Yue Zhang: orcid.org/0000-0002-5068-2260

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