Improving the performance of membrane backwash system for efficient and stable wettability process during oil/water separation

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dc.contributor.authorMopeli, Motebang Josias
dc.contributor.co-supervisorAlugongo, A. A., Prof.
dc.contributor.co-supervisorSob, P. B., Dr.
dc.contributor.supervisorTengen, T. B., Prof.
dc.date.accessioned2024-08-08T10:45:50Z
dc.date.available2024-08-08T10:45:50Z
dc.date.issued2022-10
dc.descriptionM. Tech. (Department of Mechanical Engineering, Faculty of Engineering and Technology), Vaal University of Technology.en_US
dc.description.abstractMembrane technology has enormous potential for oil/water separation applications. However, membrane performance is hampered by the ongoing fouling issue. Membrane fouling does not only affect the water permeability and separation efficiency but it also reduces the membrane lifespan. Numerous studies on backwash optimization have been conducted to reduce the fouling effect. However, it's worth mentioning that none of the studies in membrane backwash on oil/water separation applications has attempted to improve the cleaning procedure by identifying critical operation conditions through numerical model simulation and experimentation. In the past, accurate modelling of the backwash flow to dislodge the foulants found on the membrane pores or surfaces (concentration polarization) in pressure-driven membrane processes was hindered by complex couplings between the flow equations and the variable operating properties. However, the developed backwash model in this study is based on Navier Stokes laws which govern the entire flow field that incorporate the backwash media flow domain, and oil droplet dislodgement on the membrane domain. The varying nature of flow necessitates different modelling methodologies to help predict the behaviour of backwash flow. As such, Navier Stokes's laws governing the fluid flow were the obvious choice, due to their high accuracy and diversity in describing a whole set of flow phenomena:, from laminar to turbulent under Newtonian flow. Additionally, incorporating computational fluid dynamics (CFD) ANSYS Fluent numerical model simulation, as a preliminary evaluation tool to improve the backwash cleaning efficiency for oil/water separation application has shown to be an effective approach. This developed backwash model depends heavily on the backwash critical operating parameters such as temperature, driving back-pressure, and the subsequent backwash flow velocity. The theoretical numerical simulation model and experimental results were in good agreement that oil droplets can be dislodged effectively, only if the critical backwash operating conditions for oil/water separation application are identified and utilized. These critical operating parameters are identified to improve the backwash system, such as the thermal forces applied to lower the oil viscosity (critical temperature 0 65 c) and the critical pressure (190kpa) was subsequently utilized to loosen the interfacial tension force(adhesive forces). Consequently, the oil droplet blockage was easily dislodged by the backwash flowmedia (backwash velocity). Ultimately, this study investigated the dynamic relationship of the proposed critical operating parameters (temperature, pressure, and the subsequent backwash flow velocity) with membrane material capable of withstanding this proposed intense backwash procedure. The evaluation criteria were focused on permeate flux recovery, thermal stability, and the ability of the membrane to withstand harsh operating conditions during the backwash procedure. Consequently, this study developed an improved backwash cleaning procedure in relation to membrane material selection for efficient wettability which has proven to be an effective approach to control fouling during oil/water separation. According to the results obtained, the use of critical backwash pressure resulted in efficient fouling removal. In addition, the thermal stability of ceramic membrane permits the use of high temperature by backwash parameter to lower the oil droplets viscosity, subsequently allowing easy dislodgement of foulants found on the membrane structure. Consequently, this attempt to exploit the research gap in membrane backwash has led to this dissertation contributing to advancing new knowledge of membrane technology for application in oil/water separation. The contributions of the project includes: 1. Establishing the most efficient backwash process, through the identification of critical operating conditions (temperature, pressure, and the subsequent backwash flow velocity) using Navier Stokes laws under fluid flow modelling. 2. Designing a numerically simulated model by utilizing computational fluid dynamics (CFD) ANSYS Fluent software tool, as a preliminary evaluation measure, to validate an improved backwash procedure 3. Establishing an improved backwash cleaning procedure in relation to membrane material design for efficient wettability to mitigate fouling during oil/water separation.
dc.identifier.urihttps://hdl.handle.net/10352/759
dc.language.isoenen_US
dc.publisherVaal University of Technologyen_US
dc.subjectBackwashen_US
dc.subjectFoulingen_US
dc.subjectModellingen_US
dc.subjectCritical operating conditionen_US
dc.subjectFlux recoveryen_US
dc.subject.lcshDissertations, Academic -- South Africa.en_US
dc.subject.lcshMembranes (Technology).en_US
dc.subject.lcshComputational fluid dynamics.en_US
dc.titleImproving the performance of membrane backwash system for efficient and stable wettability process during oil/water separationen_US
dc.typeThesisen_US
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