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@PHDTHESIS{Lohaus:843415,
      author       = {Lohaus, Johannes},
      othercontributors = {Wessling, Matthias and Lammertink, Rob G. H.},
      title        = {{M}ultiphase dynamics of colloidal deposition and
                      resuspension at membranes},
      volume       = {22},
      school       = {Rheinisch-Westfälische Technische Hochschule Aachen},
      type         = {Dissertation},
      address      = {Aachen},
      publisher    = {RWTH Aachen University},
      reportid     = {RWTH-2022-03122},
      series       = {Aachener Verfahrenstechnik Series AVT.CVT - chemical
                      process engineering},
      pages        = {1 Online-Ressource : Illustrationen},
      year         = {2021},
      note         = {Englische und deutsche Zusammenfassung. - Veröffentlicht
                      auf dem Publikationsserver der RWTH Aachen University 2022;
                      Dissertation, Rheinisch-Westfälische Technische Hochschule
                      Aachen, 2021},
      abstract     = {Colloidal fouling significantly limits the performance of
                      membrane filtration processes. In particular, the complex
                      interplay between surface potentials and hydrodynamic
                      interactions on the pore-scale level pose a big challenge
                      for science. Numerical simulations accompanied by
                      microfluidic experiments enable to visualize the mechanisms
                      occurring during fouling and thus helping to decode the
                      fouling processes. This thesis used coupled computational
                      fluid dynamics - discrete element methods (CFD-DEM)
                      simulations to examine pore-scale mechanisms during membrane
                      fouling and membrane backwashing. The simulations were
                      accompanied by microfluidic experiments. The clogging
                      behavior was analyzed inside varying pore structures with
                      CFD-DEM simulations and compared to experimental findings
                      from literature. The simulations revealed a dominant role of
                      the inner pore structure, which is consistent with
                      experimental observations from literature. The origin of
                      clogging relied on a variety of parallel occurring
                      processes: (1) adsorption on the constriction entrance; (2)
                      interparticle interaction leading to adsorption; (3) gliding
                      of adsorbed and loosely bond particles and, (4) particle
                      resuspension. In membrane backwashing, particle resuspension
                      plays an important role and was therefore investigated in
                      more detail. Simulations and experiments both revealed that
                      the backwash is decisively controlled by particle clusters
                      instead of single-particle effects. This clarifies that
                      single-particle models are not representative of describing
                      mechanisms occurring during backwash. Two dominant events of
                      backwash were identified from the simulations and
                      experiments: (1) partial resuspension of particle clusters
                      and, (2) orientation of attached particle clusters in the
                      region of lower drag. Another important point in membrane
                      fouling is temperature dependency which is only minorly
                      addressed in literature. This thesis presents a systematic
                      analysis of experimental and numerical study for
                      particle-laden flow through a membrane mimicking pore-like
                      channel under the influence of temperature. The effect of
                      temperature on colloidal aggregation was incorporated by
                      attractive and repulsive temperature-dependent potentials
                      between particles and membrane. This study showed that are
                      still gaps between theory and experimental observation,
                      which have to be resolved in future studies. Another
                      property which is of decisive interest in understanding
                      colloidal fouling is the softness of the particle. The role
                      of softness during filtration was studied with the help of
                      CFD-DEM simulations. The simulations demonstrated that soft
                      particles arrange in highly-ordered and compact filter cake
                      structures due to hydrodynamic stress. Therefore, the soft
                      filter cake caused significantly higher resistance in
                      comparison to hard filter cakes. Furthermore, the
                      simulations revealed that cake relaxation of soft filter
                      cakes is fully reversible, whereas a short-term flux
                      increase can lead to irreversible changes in cake structure.
                      In summary, this thesis highlights and illustrates
                      microscopic events of particle deposition and resuspension,
                      which will ultimately help to understand colloidal fouling
                      and make membrane backwashing more efficient.},
      cin          = {416110},
      ddc          = {620},
      cid          = {$I:(DE-82)416110_20140620$},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      doi          = {10.18154/RWTH-2022-03122},
      url          = {https://publications.rwth-aachen.de/record/843415},
}