High-performance biofilm photobioreactor based on a GeO2–SiO2–chitosan-medium-coated hollow optical fiber

• A new BPBR with a GeO2–SiO2–chitosan-medium- (GSCM-) coated hollow optical fiber was proposed.
• The physicochemical properties of the GSCM-coated fiber were investigated.
• The biofilm and its' hydrogen production performance were investigated.
• The BPBR yielded fairly stable long-term performance with a high hydrogen production rate.

To improve hydrogen production performance, this paper describes a novel approach for fabricating a biofilm photobioreactor by adsorption of the photosynthetic bacteria (PSB) Rhodopseudomonas palustris CQK 01 on a hollow optical fiber (HOF) with a GeO2–SiO2–chitosan medium (GSCM) coating. The composition of the coating is analyzed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The biocompatibility of the GSCM-coated HOF and the PSB in the hungry condition are examined. We also quantitatively investigate the biofilm dry weight; protein, polysaccharide, bacteriochlorophyll, carotenoid, and ATP contents of the biofilm cell; and average H2 production rates. The GSCM-coated HOF exhibits enhanced the biofilm biomass, improved the biofilm activity, and an increased H2 production rate. The proposed photobioreactor yielded fairly stable long-term performance with a hydrogen production rate of 2.65 mmol/L/h, which is 1.56 and 1.51 times higher than those of photobioreactors with an uncoated HOF and with a fiber having a roughened surface obtained by wrapping it in wire mesh, respectively.