Feb 21 2019 04:00 PM
Feb 21 2019 06:00 PM
Ph.D. Proposal Defense
Date: Thursday February 21, 2019 | 4:00 - 6:00 p.m.
Venue: Bldg. 5, Level 5, Room 5220
Biofilm morphology engineering: a strategy to improve the performance of
reverse osmosis membrane systems
Biofouling represents a major limitation in the use of membranes for water treatment. Biofilm occurrence in membrane systems is considered inevitable. To solve or minimize the negative impacts of biofouling, a clear understanding of biofilm development is needed. A biofilm is comprised of bacterial cells embedded in an extracellular polymeric substances (EPS) matrix. As a result, biofilms, and the EPS component specifically, exhibit diffusional and mechanical properties characteristic of solvated hydrogels. As biofilm starts to develop on the membrane, the hydraulic resistance of the membrane system starts to increase. It is important to fully elucidate the origin and mechanisms of biofilm hydraulic resistance. It is hypothesized that the biofilm hydraulic resistance is a function of the biofilm structural properties (thickness, porosity, and roughness) and mechanical characteristics (rigidity, viscoelasticity, density). It seems that our knowledge of how the structural properties of different biofilms affect membrane performance parameters remains incomplete. The main objective of this Ph.D. study is to assess the physical and hydraulic properties of biofilms. Optical coherence tomography (OCT) will be used as a primary tool to investigate biofilm structural characteristics in-situ of different types of biofilms. Additionally, membrane autopsies at the end of the experiment will be performed to characterize the accumulated fouling. The proposed studies will focus on the i) impact of biodegradable carbon and phosphate load of the system on biofilm structure and hydraulic properties; ii) cleanability of the developed biofilms under various biodegradable nutrient loads; iii) effect of operating conditions (feed channel pressure, cross-flow velocity and permeate production) on biofilm morphology and permeability; and iv) the combined effect of the nutrient load and operating conditions on biofilm hydraulic resistance and cleanability. It is anticipated that the assessment of biofilm structural properties will help manipulate and control biofilm growth to decrease the impact of biofouling in membrane systems.
Luisa received her BSc from Monterrey Institute of Technology and Higher Education (ITESM) in Industrial Engineering. She received her MSc degree in Environmental Sciences and Engineering from King Abdullah University of Science and Technology and is currently pursuing a Ph.D. under the supervision of Professor Johannes Vrouwenvelder. His research work is in biofilm morphology in reverse osmosis membrane systems.