Yongxu (Frank) Chen | ALES Graduate Seminar

Date(s) - 21/12/2020
1:00 pm - 2:00 pm

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.

This is an ALES MSc Final Exam Seminar by Frank Chen. This seminar is open to the general public to attend via Zoom (link below).

Thesis Topic: Detection of Biofilm Forming Microbes Using Electrochemical Methods

Seminar Abstract:

Microbiologically Influenced Corrosion (MIC) and biofouling are major challenges to operators who manage oil & gas systems. The root of these threats is the formation and accumulation of biofilms in piping systems due to the agglomeration of both biotic components (e.g. bacteria, archaea and extracellular polymeric substances) and abiotic materials (e.g. inorganic solids). These biofilms adhere to the inner surfaces of pipelines and evolve over time, depending on surrounding environmental conditions, eventually lead to corrosion.  In this study, a novel in-situ method to detect the presence of biofilm-forming bacteria has been proposed based on capacitance measurements using the Electrochemical Impedance Spectroscopy (EIS) technique. Two probe types were assessed to measure the growth of bacteria: 1) a parallel plate system to measure total bacteria concentration (planktonic and sessile), and 2) a small-scale Interdigitated Electrode (IDE) system to measure the bacteria concentration (planktonic and sessile). Surface areas and gap sizes of the various probes were also evaluated to determine their effect on measuring sensitivities. In both series of tests, Pseudomonas.putida was used as the model bacteria due to its ability to grow rapidly as a biofilm former and common presence in MIC conditions. Upon the introduction of the microorganism to the system, EIS patterns collected were correlated to the observed bacterial concentration over time. A model circuit was also developed to determine the effective capacitance at different bacteria concentrations. Both the parallel plate and IDE systems were able to detect the planktonic bacteria concentration change when a threshold was reached. The effect of the surface area and the parallel plate system’s gap size seems to play a role in the effective capacitance value obtained during the test. The IDE system was found hard to detect any sessile bacteria activities due to the rapid growth of bacteria cells and low EIS testing current.  This “proof of concept” study demonstrates the potential for a viable, real-time detection method for systems susceptible to bio-fouling and/or MIC.


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