Experimental and numerical simulation of degradation of pollutants in water by microbubble-enhanced cold plasma activation -Degradation - Effect of pollutants’ initial concentration

• Author / Creator

  Shahsavari, Nima

• The necessity to secure reliable water resources has always been a challenge for human societies. Numerous factors contribute to heightened concerns, often resulting in serious crises for governments striving to ensure the provision of clean potable water
  for diverse purposes. At the same time, overpopulation, global warming, and industrial growth have motivated researchers to think about alternative ways to provide, recycle, reuse and treat water resources. Besides, increased access to social media and stricter environmental regulations compel industry sectors to find suitable, efficient, and feasible approaches to treat their wastewater, so that treated water can be safely disposed of to water bodies or reused in similar applications. There has been a myriad of conventional methods for water and wastewater treatments some of which are still frequently used. However, a more advanced approach capable of being utilized for a wide range of pollutants present in water is still an open research avenue.
  First part of this thesis is devoted to coupling cold plasma activation with hydrodynamic cavitation to leverage better mass transfer between gas and liquid phases via microbubble generation and collapse. A modified Venturi tube with an opening is used to allow the self-entrainment of air as the plasma gas into the water flow. Three sample pollutants widely observed in wastewater streams are studied i.e., two
  antibiotics (sulfathiazole and norfloxacin) and an azo dye (methylene blue). The effects of initial concentration and water flow rate are investigated. Energy yield and degradation kinetics of experiments are also elaborated and applications are extended to larger volumes to show the ability of method to be applied in larger capacities.
  In the second part, Computational Fluid Dynamic (CFD) simulations are performed to study the interactions in a three phase system. Cavitation effect is elaborated in detail along with the impact from air as the plasma activated gas. Effect of different water flow rates on the generation and expansion of cavitating bubbly flow is studied
  and results are validated versus experiments that were conducted in the first chapter. Transient simulations are performed in ANSYS Fluent 2020R2 commercial CFD software. Reynolds Averaged Navier-Stokes (RANS) models are utilized to capture turbulence phenomena and mixture model is considered for multiphase flow. Post processing of results are performed in CFD-Post to better understand the dynamics and physical behavior of the system.

• Subjects / Keywords

  • Plasma
  • Cavitation
  • water treatment
  • CFD
  • Initial concentration
  • Methylene Blue

• Graduation date

  Spring 2024

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-4n8x-5527

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.