Electrochemical determination of anaerobic microbial decay coefficients

The biokinetics of attached and suspended bacteria are an essential component of activated sludge models, anaerobic digestion models and biofilm models. These parameters are often assumed or “confirmed” based on the goodness-of-fit of the bioprocess models. Using a microbial fuel cell with a baffled reactor chamber, the attached- and mixed-growth microbial decay coefficients were evaluated under anaerobic conditions. The capability for real-time voltage recording allows easy and accurate measurement of the anaerobic microbial decay coefficients (bL, lysis-regrowth approach), which were determined to be 0.11 ± 0.01 and 0.15 ± 0.01 d−1 for attached (to anode) and mixed (present in the anode chamber) growth microorganisms, respectively. The corresponding half-saturation constants using glucose as a substrate were 204 ± 10 and 123 ± 1 mg COD l−1. Hence, like an oxygen uptake rate-based approach to measure the microbial kinetics under aerobic conditions, the electrochemical recording provides an attractive method to measure anaerobic microbial decay coefficients.