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Simultaneous Nitrogen and Phosphorus Removal in Sequencing Batch Reactors and Continuous Wastewater Treatment System

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Title: Simultaneous Nitrogen and Phosphorus Removal in Sequencing Batch Reactors and Continuous Wastewater Treatment System
Author: Tao, Tao
Department: School of Engineering
Program: Engineering
Advisor: Sheng, Chang
Abstract: Simultaneous nitrification & denitrification (SND) and simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) have attracted more and more attention nowadays. Normally, nitrogen in the wastewater was removed via aerobic nitrification and anaerobic denitrification; while phosphorus is removal via anaerobic phosphorus release and aerobic phosphorus uptake by phosphorus accumulating organisms (PAOs). However, more and more researchers have successfully observed aerobic denitrification and phosphorus removal via the nitrite/nitrate pathway. The sequential batch reactor (SBR) configuration is the most frequently used to achieve SND/SNDPR under conditions of low dissolved oxygen (DO) concentration or intermittent aeration. Moreover, the SNDPR via denitrifying phosphorus-accumulating organisms (DPAOs) was reported in DEPHANOX. Despite the simultaneous nutrient removal, its disadvantage is also obvious, including the fluctuation in SNDPR performance, sensitivity to the changes in the process conditions and wastewater characteristics, and the complexity in the process operation and control, and so on. This thesis focused on the evaluation of SND/SNDPR performance in anoxic/oxic (A/O) SBRs with cycles consisting of various anoxic and oxic period distributions and a continuous-flow tubular anaerobic SBR (TAnSBR) which was designed to mimic the strict control of anaerobic and aerobic conditions in SBR. In this thesis, the nitrogen and phosphorus removal mechanisms in the tested bioreactor systems were investigated through long-term operations, cycle tests, and batch tests with different wastewater characteristics and process conditions. The results showed that excellent SND performance can be achieved in either SBR or TAnSBRs. Despite the excellent nitrogen removal performance, phosphorus removal efficiency fluctuated. the anaerobic and aerobic zones of SBR. In this thesis, long-term operations, cycle tests, and batch tests were conducted to reveal the nitrogen and phosphorus removal mechanisms. In this Ph.D. project, the results showed excellent SND performance in either SBR or TAnSBRs. Despite the excellent nitrogen removal performance, phosphorus removal efficiency fluctuated. The results by Illumina MeSeq Sequencing confirmed the existence of SND species and a low proportion of species contributed to SNDPR. The study confirmed that SND could be successfully achieved in A/O SBR and continuous-flow TAnSBR. The knowledge generated from this Ph.D. program can further promote the simplification of the SND systems and the investigation of nitrogen and phosphorus removal mechanisms.
URI: https://hdl.handle.net/10214/26414
Date: 2021-09-09
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Embargoed Until: 2022-09-09


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