Experimental study in optimizing enzyme-based polymeric membrane bioreactors*

Enzyme-coated polymeric membranes are versatile catalysts for biofuel production and other chemical production from feedstocks like plant biomass. Such bioreactors are more energy efficient than high-temperature methods because enzymes catalyze chemical reactions near room temperature. A major challenge in processing plant biomass is the presence of lignin, a complex aromatic polymer that resists chemical breakdown. Therefore, membranes coated with enzymes such as laccase that can degrade lignin are sought for energy extraction systems. We present an experimental study on optimizing an enzyme-based membrane bioreactor by modelling the tradeoff between high flow rate and short dwell time in the active region. Zero flow rate voltammetry experiments measure the electrochemical activity for a specific enzyme and coverage density, both for screening enzyme variants and providing inputs to the reactor model. Membrane pore size and density are verified with electron microscopy. Our flow-through spectroscopy device with laccase-coated membranes and a colorimetric laccase activity indicator is designed to measure reaction rate and percent conversion as a function of flow rate and membrane microstructure.