1 research outputs found
Microbial fuel cell-based biosensors for estimation of biochemical oxygen demand and detection of toxicity
PhD ThesisThere is a global requirement to establish state-of-the-art monitoring techniques for analysis of
water quality to ensure that standards are maintained with increasing domestic and industrial
water usage. An important parameter used in water quality assessment is Biochemical
Oxygen Demand (BOD), a measurement of the oxygen consumed by micro-organisms in
the oxidation of biodegradable organic material. BOD measurements have been correlated
with the output from Microbial Fuel Cells (MFCs), which are a potential solution for online
monitoring of wastewaters. Previously studied MFC sensors have had a limited amperometric
range of approximately 250 mg/l O2 BOD5; which is often attributed to substrate saturation
of the anode biofilm.
In this work, a proof-of-concept configuration of multi-stage MFCs connected hydraulically
in series was tested extensively to eliminate the saturation effect and extend the sensing
range. The summed current generated by a three-stage array was calibrated against BOD5
for different glucose-glutamic acid concentrations in artificial wastewater. A linear response
was obtained up to approximately 750 mg/l O2 BOD5 with R2 > 99% and average standard
deviation < 9%. The array range was three times greater than obtained with the first
MFC operating individually. Batch-mode sensors were also operated to develop greater
understanding of the long-term performance characteristics and establish how changes in
operating parameters affect sensor calibration.
Additionally, the effect of toxicant presence (4-nitrophenol) on the multi-stage sensor response
was studied. Toxic and low BOD events which both resulted in current decreases could be
differentiated using the MFC-based sensor. The modular mode of operation permitted highstrength
BOD wastewaters to be measured online without dilution and an explicit differentiation
between toxic and low BOD events based on the ordered response of MFCs. The MFC-based
sensors were tested with samples of real influent wastewater and recommendations have
been made for ‘best practice’ operation and calibration of MFC sensors