Modelling gas–liquid mass transfer in wastewater treatment: when current knowledge needs to encounter engineering practice and vice versa Andreia Amaral , Sylvie Gillot , Manel Garrido-Baserba , Ahlem Filali , Anna M. Karpinska , Benedek G. Plósz , Christopher De Groot , Giacomo Bellandi , Ingmar Nopens , Imre Takács , Izaro Lizarralde , Jose A. Jimenez , Justine Fiat , Leiv Rieger , Magnus Arnell , Mikkel Andersen , Ulf Jeppsson , Usman Rehman , Yannick Fayolle , Youri Amerlinck and Diego Rosso ABSTRACT Gas–liquid mass transfer in wastewater treatment processes has received considerable attention over the last decades from both academia and industry. Indeed, improvements in modelling gas– liquid mass transfer can bring huge benefits in terms of reaction rates, plant energy expenditure, acid–base equilibria and greenhouse gas emissions. Despite these efforts, there is still no universally valid correlation between the design and operating parameters of a wastewater treatment plant and the gas–liquid mass transfer coefficients. That is why the current practice for oxygen mass transfer modelling is to apply overly simplified models, which come with multiple assumptions that are not valid for most applications. To deal with these complexities, correction factors were introduced over time. The most uncertain of them is the α-factor. To build fundamental gas–liquid mass transfer knowledge more advanced modelling paradigms have been applied more recently. Yet these come with a high level of complexity making them impractical for rapid process design and optimisation in an industrial setting. However, the knowledge gained from these more advanced models can help in improving the way the α-factor and thus gas–liquid mass transfer coefficient should be applied. That is why the presented work aims at clarifying the current state-of-the-art in gas–liquid mass transfer modelling of oxygen and other gases, but also to direct academic research efforts towards the needs of the industrial practitioners. Andreia Amaral (corresponding author) Giacomo Bellandi Ingmar Nopens Usman Rehman Youri Amerlinck BIOMATH, Department of Data Analysis and Mathematical Modelling, Ghent University, Coupure Links 653, 9000 Ghent, Belgium E-mail: andreia.amaral@ugent.be; andreia.amaral@tecnico.ulisboa.pt Andreia Amaral MARETEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal Sylvie Gillot Irstea, UR REVERSAAL, centre de Lyon- Villeurbanne, 5 rue de la Doua, Villeurbanne cedex F-69926, France Manel Garrido-Baserba Diego Rosso Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175, USA and Water-Energy Nexus Center, University of California, Irvine, CA 92697-2175, USA Ahlem Filali Justine Fiat Yannick Fayolle Irstea, UR PROSE, 1 Rue Pierre-Gilles de Gennes – CS 10030, F-92761, Antony Cedex, France Key words | aeration, alpha-factor, computational fluid dynamics, greenhouse gas, mass transfer coefficient This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for non-commercial purposes with no derivatives, provided the original work is properly cited (http://creativecommons.org/ licenses/by-nc-nd/4.0/). 607 © 2019 The Authors Water Science & Technology | 80.4 | 2019 doi: 10.2166/wst.2019.253 Downloaded from https://iwaponline.com/wst/article-pdf/80/4/607/621645/wst080040607.pdf by guest on 01 June 2020