{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T20:44:47Z","timestamp":1791924287560,"version":"4.3.4"},"reference-count":47,"publisher":"American Chemical Society (ACS)","issue":"40","license":[{"start":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T00:00:00Z","timestamp":1790640000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003459","name":"Guizhou University","doi-asserted-by":"publisher","award":["[2019] 53"],"award-info":[{"award-number":["[2019] 53"]}],"id":[{"id":"10.13039\/501100003459","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,13]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Dissolved oxygen (DO) regulation is essential for one-stage partial nitrification\u2013anammox (PNA), which requires oxygen supply for nitrite production while protecting anammox bacteria from excessive oxygen exposure. In this study, a computational fluid dynamics (CFD) model coupled with a population balance model, species transport model, and gas\u2013liquid mass transfer model was developed to investigate DO regulation in an airlift reactor (ALR). The effects of aeration mode and superficial gas velocity on DO distribution, oxygen transfer, flow-field characteristics, and bubble behavior were analyzed. The results showed that annulus-rising aeration mode promoted broad oxygen dispersion, producing a relatively homogeneous DO field with a low-DO zone fraction of only 5%. In contrast, center-rising aeration mode confined oxygen transfer mainly to the riser and maintained lower DO in the downcomer, increasing the low-DO zone fraction to 52%. Under center-rising aeration, increasing superficial gas velocity from 0.5 to 3.0 cm\/s enhanced gas holdup, liquid circulation, interfacial area, and kLa. Passive-tracer analysis further showed that increasing superficial gas velocity shortened the residence times in both the riser and downcomer, while regional tracer transport was faster in the CR-ALR than in the AR-ALR at 1.5 cm\/s. A superficial gas velocity of 1.5 cm\/s achieved the best balance between oxygen transfer enhancement and low-DO zone preservation. This study provides guidance for constructing spatially differentiated oxygen environments in airlift reactors for one-stage PNA.<\/jats:p>","DOI":"10.1021\/acsomega.6c06878","type":"journal-article","created":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T06:02:15Z","timestamp":1790661735000},"page":"61465-61478","source":"Crossref","is-referenced-by-count":0,"title":["CFD-Based Investigation\nof the Effects of Aeration\nMode and Superficial Gas Velocity on Dissolved Oxygen Distribution\nand Oxygen Transfer in an Airlift Reactor"],"prefix":"10.1021","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-1959-5783","authenticated-orcid":true,"given":"Jiangbo","family":"Qiu","sequence":"first","affiliation":[{"name":"Guizhou University , , ,","place":["Guiyang, P. R. China, 550025"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianquan","family":"Ao","sequence":"additional","affiliation":[{"name":"Guizhou University , , ,","place":["Guiyang, P. R. China, 550025"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9387-5364","authenticated-orcid":true,"given":"Wan","family":"Wang","sequence":"additional","affiliation":[{"name":"Guizhou University , , ,","place":["Guiyang, P. R. China, 550025"]},{"name":"Technology Innovation Center of Special Equipment Inspection and Testing Technology, Administration for Market Regulation of Guizhou Province , ,","place":["Guiyang, P. R. China, 550014"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,29]]},"reference":[{"issue":"1","key":"2026101315095293700_cit1","doi-asserted-by":"publisher","first-page":"1353","DOI":"10.1021\/acssuschemeng.8b05055","article-title":"Using Partial Nitrification\nand Anammox To Remove Nitrogen from Low-Strength Wastewater by Co-immobilizing\nBiofilm inside a Moving Bed Bioreactor","volume":"7","author":"Chen","year":"2019","journal-title":"ACS\nSustainable Chem. 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Technol."},{"issue":"19","key":"2026101315095293700_cit4","doi-asserted-by":"publisher","first-page":"7624","DOI":"10.1021\/acs.est.3c00491","article-title":"Improved Properties\nand Enhancement Strategies of Hydroxyapatite-Based Functional Granular\nSludge for a High-Rate Partial Nitritation\/Anammox System","volume":"57","author":"Chen","year":"2023","journal-title":"Environ. Sci. Technol."},{"issue":"1","key":"2026101315095293700_cit5","doi-asserted-by":"publisher","first-page":"9","DOI":"10.1021\/acs.est.0c00276","article-title":"Critical Analysis of\nBiomass Retention Strategies in Mainstream and Sidestream ANAMMOX-Mediated\nNitrogen Removal Systems","volume":"55","author":"Kosgey","year":"2021","journal-title":"Environ. Sci. Technol."},{"issue":"6","key":"2026101315095293700_cit6","doi-asserted-by":"publisher","first-page":"3901","DOI":"10.1021\/acsestwater.6c00316","article-title":"Microbial Ecological\nSuccession and Organic Matter Metabolic Mechanisms in a Two-Stage\nPartial Nitritation-Anammox Process for Swine Wastewater Treatment","volume":"6","author":"Kong","year":"2026","journal-title":"ACS ES&T Water"},{"issue":"17","key":"2026101315095293700_cit7","doi-asserted-by":"publisher","first-page":"10859","DOI":"10.1021\/acs.est.0c01314","article-title":"Improving Efficiency\nand Stability of Anammox through Sequentially Coupling Nitritation\nand Denitritation in a Single-Stage Bioreactor","volume":"54","author":"Li","year":"2020","journal-title":"Environ. Sci. Technol."},{"issue":"23","key":"2026101315095293700_cit8","doi-asserted-by":"publisher","first-page":"8715","DOI":"10.1021\/es801391u","article-title":"Partial Nitrification\nAchieved by Pulse Sulfide Doses in a Sequential Batch Reactor","volume":"42","author":"Erguder","year":"2008","journal-title":"Environ. Sci. Technol."},{"issue":"11","key":"2026101315095293700_cit9","doi-asserted-by":"publisher","first-page":"4952","DOI":"10.1021\/acs.iecr.3c04139","article-title":"Characteristics of Bubbly\nFlow, Mass Transfer, and CO2 Absorption in a Two-Stage Internal Loop\nAirlift Reactor Assembly with a Diamond-Shaped Guide Baffle","volume":"63","author":"Song","year":"2024","journal-title":"Ind. Eng. Chem. 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Manage."},{"key":"2026101315095293700_cit12","doi-asserted-by":"publisher","DOI":"10.1016\/j.jenvman.2021.113271","article-title":"Enhancing autotrophic nitrogen removal with\na novel dissolved oxygen-differentiated airlift internal circulation\nreactor: Long-term operational performance and microbial characteristics","volume":"296","author":"Wang","year":"2021","journal-title":"J. Environ. Manage."},{"key":"2026101315095293700_cit13","doi-asserted-by":"publisher","DOI":"10.1016\/j.biortech.2022.127261","article-title":"Dual inner\ncirculation\nand multi-partition driving single-stage autotrophic nitrogen removal\nin a bioreactor","volume":"355","author":"Chen","year":"2022","journal-title":"Bioresour. 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Environ.\nProt."},{"key":"2026101315095293700_cit29","doi-asserted-by":"publisher","DOI":"10.1016\/j.jwpe.2024.105078","article-title":"CFD investigation of dissolved oxygen\ndistribution in a full-scale aeration tank of an industrial wastewater\ntreatment plant","volume":"59","author":"Shah","year":"2024","journal-title":"J. Water Process Eng."},{"key":"2026101315095293700_cit30","doi-asserted-by":"publisher","DOI":"10.1016\/j.biortech.2024.131588","article-title":"Effect of aeration on oxygen transfer characteristics\nin integrated wastewater treatment systems utilizing mass transfer\nmodel and computation fluid dynamics methods","volume":"414","author":"Sun","year":"2024","journal-title":"Bioresour. Technol."},{"key":"2026101315095293700_cit31","doi-asserted-by":"publisher","DOI":"10.1016\/j.jenvman.2025.127597","article-title":"Effect of bubble size on oxygen transfer during\naeration of integrated wastewater treatment systems","volume":"394","author":"Si","year":"2025","journal-title":"J. Environ. Manage."},{"key":"2026101315095293700_cit32","doi-asserted-by":"publisher","first-page":"61","DOI":"10.1016\/j.cej.2018.01.039","article-title":"Mass transfer\nintensification\nin a novel airlift reactor assembly with helical sieve plates","volume":"342","author":"Zheng","year":"2018","journal-title":"Chem. Eng. J."},{"key":"2026101315095293700_cit33","doi-asserted-by":"publisher","first-page":"121","DOI":"10.1016\/j.cherd.2023.08.004","article-title":"Computational fluid\ndynamics study\nof gas-liquid mass transfer in concentric tube airlift reactor with\nhelical baffle","volume":"198","author":"Chen","year":"2023","journal-title":"Chem. Eng. Res. Des."},{"issue":"12","key":"2026101315095293700_cit34","doi-asserted-by":"publisher","first-page":"2377","DOI":"10.1016\/j.cherd.2013.06.002","article-title":"Hydrodynamics and mass\ntransfer characteristics in an internal loop airlift reactor with\nsieve plates","volume":"91","author":"Luo","year":"2013","journal-title":"Chem. Eng. Res. Des."},{"key":"2026101315095293700_cit35","doi-asserted-by":"publisher","first-page":"494","DOI":"10.1016\/j.cej.2011.09.078","article-title":"Hydrodynamics and mass transfer characteristics\nin an internal loop airlift reactor with different spargers","volume":"175","author":"Luo","year":"2011","journal-title":"Chem. Eng. J."},{"key":"2026101315095293700_cit36","doi-asserted-by":"publisher","first-page":"2711","DOI":"10.1109\/ACCESS.2017.2666542","article-title":"PBM-CFD\nInvestigation\nof the Gas Holdup and Mass Transfer in a Lab-Scale Internal Loop Airlift\nReactor","volume":"5","author":"Zhang","year":"2017","journal-title":"IEEE Access"},{"key":"2026101315095293700_cit37","doi-asserted-by":"publisher","DOI":"10.1016\/j.biortech.2023.128599","article-title":"Achieving superior nitrogen\nremoval in an air-lifting\ninternal circulating reactor for municipal wastewater treatment: Performance,\nkinetic analysis, and microbial pathways","volume":"371","author":"Han","year":"2023","journal-title":"Bioresour.\nTechnol."},{"issue":"1","key":"2026101315095293700_cit38","doi-asserted-by":"publisher","first-page":"367","DOI":"10.1002\/cjce.22943","article-title":"Effect of aeration mode on the performance\nof center- and annulus-rising internal-loop airlift bioreactors","volume":"96","author":"Han","year":"2018","journal-title":"Can. J. Chem. Eng."},{"key":"2026101315095293700_cit39","doi-asserted-by":"publisher","first-page":"79","DOI":"10.1016\/j.cherd.2025.05.049","article-title":"Bubble size, mass transfer, and hydrodynamics\nin a self-priming aeration draft tube reactor","volume":"219","author":"Wang","year":"2025","journal-title":"Chem. Eng. Res. Des."},{"issue":"5","key":"2026101315095293700_cit40","doi-asserted-by":"publisher","DOI":"10.1016\/j.jece.2023.110800","article-title":"Computational studies of airlift\nand stirred airlift\nbioreactors with non-Newtonian fluid: A comparison of hydrodynamics\nand gas-liquid mass transfer","volume":"11","author":"Xu","year":"2023","journal-title":"J. Environ. Chem.\nEng."},{"key":"2026101315095293700_cit41","doi-asserted-by":"publisher","DOI":"10.3390\/pr11102866","article-title":"The Influence\nof Draft\nTubes on the Mass Transfer and Mixing Performance of a Pilot-Scale\nInternal-Loop Airlift Reactor","volume":"11","author":"Wang","year":"2023","journal-title":"Processes"},{"key":"2026101315095293700_cit42","doi-asserted-by":"publisher","DOI":"10.1016\/j.cej.2021.133067","article-title":"Flow regimes characteristics\nof industrial-scale center-rising airlift reactor","volume":"430","author":"Zhong","year":"2022","journal-title":"Chem. Eng. J."},{"key":"2026101315095293700_cit43","doi-asserted-by":"publisher","DOI":"10.1016\/j.chemosphere.2023.138480","article-title":"Effects\nof superficial\ngas velocity on the performance of an air-lift internal circulation\npartial nitrification-anammox granular sludge reactor","volume":"326","author":"Zhang","year":"2023","journal-title":"Chemosphere"},{"issue":"11","key":"2026101315095293700_cit44","doi-asserted-by":"publisher","first-page":"6613","DOI":"10.1002\/cjce.24907","article-title":"Gas holdup, bubble size distribution, and mass\ntransfer in an airlift reactor with ceramic membrane and perforated\nplate distributor","volume":"101","author":"Zhang","year":"2023","journal-title":"Can. J. Chem. Eng."},{"issue":"2","key":"2026101315095293700_cit45","doi-asserted-by":"publisher","DOI":"10.1063\/5.0190749","article-title":"Investigation of hydrodynamic performance in\na staggered multistage internal airlift loop reactor","volume":"36","author":"Wang","year":"2024","journal-title":"Phys. Fluids"},{"issue":"4","key":"2026101315095293700_cit46","doi-asserted-by":"publisher","first-page":"518","DOI":"10.1016\/j.icheatmasstransfer.2010.12.033","article-title":"Experimental investigation\nand CFD simulation of turbulence effect on hydrodynamic and mass transfer\nin a packed bed airlift internal loop reactor","volume":"38","author":"Moraveji","year":"2011","journal-title":"Int. Commun. Heat Mass Transfer"},{"key":"2026101315095293700_cit47","doi-asserted-by":"publisher","first-page":"221","DOI":"10.1016\/j.compfluid.2018.02.030","article-title":"Residence\ntime distribution in an\ninternal loop airlift reactor: CFD simulation versus digital image\nprocessing measurement","volume":"167","author":"Farhadian","year":"2018","journal-title":"Comput. 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