From Beijing to Dublin by UCD PhD student Huayu Cao

Six years ago, as an undergraduate student in Chemical Engineering at Beijing University of Chemical Technology (BUCT), I attended a presentation hosted by University College Dublin. It was the inaugural year of UCD-BUCT 3+1+1 Programme and I was fortunate to be selected for admission in September 2010, as a Pre-Master student, in receipt of a scholarship from the UCD College of Engineering and Architecture.

For my first two years in Dublin, I was a (taught) Master student in Chemical & Bioprocess Engineering. The intense course work, the challenging core modules and the emphasis on active learning inspired me to absorb the knowledge, to sharpen my problem-solving skills, and to develop a facility for critical-thinking. Although I didn’t recognize it at the time, the MEngSc programme provided me with the solid foundation I would need as a researcher, during the subsequent 4 years.

In September 2012, I was offered and accepted a PhD position, on a project funded by the European Research Council (ERC), under the supervision of Prof. Eoin Casey, now Head of School. Although I had undertaken a research project for my MEngSc degree, this was my first exposure to intensive, full-time research. My project relates to biofouling, a phenomenon which usually occurs at the surface of nanofiltration/reverse osmosis membranes used, for example, for water-purification. These systems operate under high pressures and, due to the high pressure, bacteria adhere to and grow on the membrane surface. This process, which is known as biofouling, leads to reduced productivity, a deterioration in water quality and increased operating costs. Water is a limiting resource in many locations worldwide and there is a real need to understand the mechanism behind biofouling, with a view to developing methods to controlling it.

My research includes a combination of laboratory-based experimental work and mathematically-based simulation. In the first year of my PhD studies, I learned to use the equipment in our laboratory and participated in experiments led by my more senior colleagues. At the same time, I was reading the literature related to initial bacteria adhesion on membranes, in order to familiarise myself with the subject area and to identify areas where I could make a real contribution. In June 2013, I established a basic model, combining both hydrodynamic effects and surface energy in the bacteria adhesion process, and I started to verify the model via carefully designed experiments. With the support of my co-workers, who critiqued my work and made valuable suggestions during our research group’s weekly update meetings, the data collection and analysis stage went smoothly and I published an associated paper (Cao et al., 2015) which was accepted for publication in November 2014. 

Inspired by this achievement, I progressed to the next step: characterisation of the mechanical properties of the biofilm. Once biofouling occurs, it is difficult to remove the biofilm from the membrane surface simply via varying shear force (i.e. essentially, by varying the velocity of the liquid flowing across the biofilm surface). This observation led us to ask fundamental questions about both the internal structure of biofilm and the mechanism of biofilm growth and, starting from this point, Dr. Olivier Habama, a post-doctoral researcher in the group, and I began to work in the area of micro-rheology. Micro-rheology is a technique for measuring the rheological (or flow) properties of a fluid, by measuring the flow path of a micro-particle in the fluid, which acts as a flow tracer. This was an entirely new area for our group, and it took me about 3 months to confirm that the approach would be applicable to our biofilm system, to develop and validate the protocol and to perform the associated experiments. Ultimately, using microbeads as ‘probes’, the three-dimensional structure and mechanical properties of the biofilm was revealed via confocal laser microscopy. The work has just been published in a Nature journal: Biofilms and Microbiomes (Cao et al., 2016).

Having now lived and studied in Ireland for six years, I feel so fortunate to have attended that fateful presentation, in BUCT in 2010 and to have made the decision to come to Ireland. Outside of my formal MEngSc and PhD studies, I’ve enjoyed being part of the tight-knit Chemical & Bioprocess Engineering community in UCD, working with classmates on an intensive group-based Design Project, in Peer-Assisted Tutorials (where I served first as a Tutee and subsequently as a Tutor) and in the Unit Operations Laboratory, where I was a Teaching Assistant, demonstrating experiments, grading reports and providing feedback to undergraduate students. Part-time work in the UCD Global Lounge and on Engineering outreach programmes has allowed me to act as an informal ambassador for UCD and I’ve been proud to return to BUCT to tell students there about my experiences in Ireland and to encourage them to follow in my footsteps.

The UCD College of Engineering and Architecture has provided me with life-changing opportunities for higher education, to be involved in advanced research and to fulfil myself, personally and professionally. I can honestly say that these have been the best years of my life!

About the Author

My name is Huayu Cao. I am currently a final year PhD student in the UCD School of Chemical & Bioprocess Engineering

PUBLICATIONS: 

Cao, H., Habimana, O., Safari, A., Heffernan, R., Dai, Y. & Casey, E. 2016. Revealing region-specific biofilm viscoelastic properties by means of a micro-rheological approach, npj Biofilms and Microbiomes, 2:5.

Cao, H., Habimana, O., Semião, A.J., Allen, A., Heffernan, R. & Casey, E., 2015. Understanding particle deposition kinetics on NF membranes: A focus on micro-beads and membrane interactions at different environmental conditions. Journal of Membrane Science, 475: 367-375.

Heffernan, R., Habimana, O., Semião, A.J.C., Cao, H., Safari, A. & Casey, E., 2014. A physical impact of organic fouling layers on bacterial adhesion during nanofiltration. Water Research, 67: 118-128.

Semião, A.J.C., Habimana, O., Cao, H., Heffernan, R., Safari, A. & Casey, E., 2013. The importance of laboratory water quality for studying initial bacterial adhesion during NF filtration processes. Water Research, 47(8): 2909-2920.

Heffernan, R., Semião, A.J.C., Desmond, P., Cao, H., Safari, A., Habimana, O. and Casey, E., 2013. Disinfection of a polyamide nanofiltration membrane using ethanol. Journal of Membrane Science, 448: 170-179.

Cao, H., English, N.J. & MacElroy, J.M.D., 2013. Diffusive hydrogen inter-cage migration in hydrogen and hydrogen-tetrahydrofuran clathrate hydrates. Journal of Chemical Physics, 138(9): 094507.

International Presentation

Cao, H., Habimana, O., Semião, A.J., Allen, A., Heffernan, R. & Casey, E., Understanding Particle Deposition Kinetics on NF membranes: A focus on micro-beads & membrane interactions at different environmental conditions. ICOM Suzhou. July 24, 2014 (Excellent poster award)