AUTHOR=Feng Xing-Hui , Wang Xiao-Jun , Li Hai-Xiang , Zhang Hai-Ya , Zhu Zong-Qiang , Liang Yan-Peng , Dong Kun , Zeng Hong-Hu 

TITLE=Integration of Zeolite Membrane Bioreactor With Granular Sludge-Based Anammox in High-Efficiency Nitrogen Removal From Iron Oxide Red Wastewater

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.932940

DOI=10.3389/fmicb.2022.932940

ISSN=1664-302X

ABSTRACT=<p>Acquisition of stable nitritation and efficient anammox play a crucial role in partial nitritation (PN) combined with anammox for nitrogen removal from ammonium-rich wastewater. Due to the limitation of ammonia-oxidizing bacteria (AOB) enrichment and nitrite-oxidizing bacteria (NOB) control in traditional membrane biological reactor (MBR), it can result in a lower nitrite production rate (NPR) and unstable PN, eventually reducing the nitrogen removal rate (NRR) <italic>via</italic> PN-anammox. In this study, we developed a zeolite membrane biological reactor (ZMBR) to enhance the PN of iron oxide red wastewater (IORW), in which the biofilm derived from the zeolite surface can provide free ammonia (FA)-containing microenvironment for AOB enrichment and NOB inhibition. The results showed that ZMBR can tolerate a higher influent nitrogen loading rate (NLR) of 2.78 kg/(m<sup>3</sup>⋅day) in comparison to the traditional MBR [2.02 kg/(m<sup>3</sup>⋅day)] and the NPR in ZMBR and traditional MBR were 1.39 and 0.96 kg/(m<sup>3</sup>⋅day), respectively. The mass concentration ratio of <inline-formula><mml:math id="INEQ1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>NO</mml:mtext><mml:mn>2</mml:mn><mml:mo>-</mml:mo></mml:msubsup></mml:math></inline-formula>-N/<inline-formula><mml:math id="INEQ2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>NH</mml:mtext><mml:mn>4</mml:mn><mml:mo>+</mml:mo></mml:msubsup></mml:math></inline-formula>-N ranged from 1.05 to 1.33 in ZMBR, suggesting a suitable condition for nitrogen removal <italic>via</italic> anammox. Subsequently, the domesticated granular sludge obtained from a paper-making wastewater treatment was used as the carrier of anammox bacteria to remove nitrogen. After 93 days of operation, the NRR was observed to be 2.33 kg/(m<sup>3</sup>⋅day) and high-throughput sequencing indicated that the relatively higher abundance (45.0%) of <italic>Candidatus</italic> Kuenenia stuttgartiensis was detected in the granular sludge of the bottom part of the reactor, which can produce more proteins and lipids, suggesting a good settleability. Overall, this study provides a high-efficient method to control PN and domesticate anammox for nitrogen removal from IORW.</p>