Enhancing continuous hydrogen production by photosynthetic bacterial biofilm formation within an alveolar panel photobioreactor

Abstract

Photofermentative hydrogen production at higher rate is desirable to make the technology of biological hydrogen production in practical application. An easy fabricating alveolar panel photobioreactor with high surface-to-volume ratio was proposed in this study to realize biofilm formation and used for developing a continuous bioprocess of hydrogen production. Effects of key operating parameters, i.e. variation in intensity of incident light, initial concentration of carbon substrate and flow rate on the rate of nitrogenase-based H2 production were investigated using response surface methodology (RSM) with Box-Behnken design. Surface and contour plots of the fitted regression model revealed that optimum H2 production rate of 57.6 mL/h/L was obtained at 125.9 μE/m2/s incident light intensity at 590 nm light wavelength, 52.4 mM initial concentration of carbon substrate and 209 mL/h flow rate. Regular groove surfaces within this photobioreactor were considered to have mutual effects on enhancement of continuous hydrogen production by enriching bacterial cell density, enhancing mass transfer of carbon substrate to facilitate release of protons and electrons, enhancing removal of molecular H2, and uniformly distribution of incident light within the photobioreactor for sufficient conversion into ATPs.