Microbial electrochemical sensor systems for rapid measurement of volatile fatty acid intermediates

Microbial electrochemical sensor systems for rapid measurement of volatile fatty acid intermediates

Biogas production from renewable sources is set to grow in Australia over the next decade. Anaerobic digestion is the key process employed to produce biogas and is being incorporated with other renewable energy production such as wind and solar. Biogas can contribute to stabilising energy supply-demand through steady baseload and on-demand variable biogas energy production. As adoption of more novel anaerobic digestion technologies increases, monitoring of key process parameters is becoming more crucial. Relatively poor process transparency accompanied with process sensitivity are key drivers to developing alternative monitoring options. One key parameter and indicator of process instability is the concentration of volatile fatty acids; metabolites formed during the anaerobic digestion process, and that build-up when the process is stressed. Current methods to measure volatile fatty acids include titration, gas chromatograph, and high-performance liquid chromatography. Unfortunately, these methods typically require an external laboratory, which can take several hours and/or require reliable manual sampling of the digestate to obtain a measurement. Consequently, there is a need for measurement alternatives to enable timely and reliable measurement of volatile fatty acids to monitor anaerobic digestion performance. Microbial electrochemical sensors show potential as a viable alternative to these problems but still face challenges in development. The themes within this thesis identify and investigate challenges to microbial electrochemical technologies. A cost-effective potentiostat design was presented as a way to overcome barriers associated with cost. As a sensor, a microbial electrochemical sensor needs to be capable of stable and predictable output, therefore a microbial electrochemical sensors biofilm growth long-term was explored in terms of cell performance to identify ageing effects on transduced signal. Lastly, to address the need for rapid measurements in high-rate anaerobic digesters, the conductivity impact on microbial electrochemical sensor biofilm response times and peak current was investigated. These interrelating studies contribute to further understanding of a promising alternate method for volatile fatty acid measurement, microbial electrochemical technologies.

This article is part of a UniSQ Thesis by publication. See Related Output.