Simultaneous enhancement of Chlorella vulgaris growth and lipid accumulation through the synergy effect between light and nitrate in a planar waveguide flat-plate photobioreactor

Interval between adjacent planar waveguides and light intensity emitted from waveguide surface were the primary two factors affecting light distribution characteristics in the planar waveguide flat-plate photobioreactor (PW-PBR). In this paper, the synergy effect between light and nitrate in the PW-PBR was realized to simultaneously enhance microalgae growth and lipid accumulation. Under an interval of 10 mm between adjacent planar waveguides, 100% of microalgae cells in regions between adjacent waveguides could be illuminated. Chlorella vulgaris growth and lipid accumulation were synchronously elevated as light intensities emitted from planar waveguide surface increasing. With an identical initial nitrate concentration of 18 mM, the maximum lipid content (41.66% in dry biomass) and lipid yield (2200.25 mg L-1) were attained under 560 lmol m(-2) s(-1), which were 86.82% and 133.56% higher relative to those obtained under 160 lmol m(-2) s(-1), respectively. The PW-PBR provides a promising way for microalgae lipid production. (C) 2017 Elsevier Ltd. All rights reserved.