Optimizing Light Distributions in a Membrane Photobioreactor via Optical Fibers To Enhance CO<sub>2</sub> Photobiochemical Conversion by a <i>Scenedesmus obliquus</i> Biofilm
Yahui Sun, Danru Duan, Haixing Chang, Chenglong Guo
Abstract
Aiming at elevating Scenedesmus obliquus biofilm growth from the perspectives of CO2 transfer enhancement and light delivery optimization, a membrane-based photobioreactor with built-in optical fibers (OF-GP-BPBR) was proposed in this work. In particular, the S. obliquus biofilm attached to the membrane featured by gas permeability could directly assimilate the CO2 molecules diffused across the membrane. The emergent light of the external light-emitting diode light sources was guided, diluted, and redistributed within the biofilm providing light energy for S. obliquus cell photoautotrophic proliferation. Responses of S. obliquus biofilm growth to various optical fiber quantities, CO2 concentrations, and initial nitrate concentrations were measured. The maximum areal S. obliquus biofilm biomass density was achieved to be 37.32 g m–2 under an initial nitrate concentration of 1.18 mM, a CO2 concentration of 10%, and an optical fiber quantity of 13. This work demonstrates a prospective approach to promote biofilm-based microalgae biomass accumulation by introducing light-guiding materials into photobioreactors.