title: Assessment of key biological and engineering design parameters for production of Chlorella zofingiensis (Chlorophyceae) in outdoor photobioreactors.
abstract: For the design of a large field of vertical flat plate photobioreactors (PBRs), the effect of four design parameters-initial biomass concentration, optical path length, spacing, and orientation of PBRs-on the biochemical composition and productivity of Chlorella zofingiensis was investigated. A two-stage batch process was assumed in which inoculum is generated under nitrogen-sufficient conditions, followed by accumulation of lipids and carbohydrates in nitrogen-deplete conditions. For nitrogen-deplete conditions, productivity was the most sensitive to initial biomass concentration, as it affects the light availability to individual cells in the culture. An initial areal cell concentration of 50 g m(-2) inoculated into 3.8-cm optical path PBR resulted in the maximum production of lipids (2.42 ± 0.02 g m(-2) day(-1)) and carbohydrates (3.23 ± 0.21 g m(-2) day(-1)). Productivity was less sensitive to optical path length. Optical path lengths of 4.8 and 8.4 cm resulted in similar areal productivities (biomass, carbohydrate, and lipid) that were 20 % higher than a 2.4-cm optical path length. Under nitrogen-sufficient conditions, biomass productivity was 48 % higher in PBRs facing north-south during the winter compared to east-west, but orientation had little influence on biomass productivity during the spring and summer despite large differences in insolation. An optimal spacing could not be determined based on growth alone because a tradeoff was observed in which volumetric and PBR productivity increased as space between PBRs increased, but land productivity decreased.
authors: Laboratory for Algae Research and Biotechnology, College of Technology and Innovation Arizona State University, 7418 Innovation Way South ISTB-3 Rm 103, Mesa, AZ 85212, USA. pzemke@asu.edu
authors: Peter E
authors: PE
authors: Zemke
authors: Milton R
authors: MR
authors: Sommerfeld
authors: Qiang
authors: Q
authors: Hu
mesh_terms: D018533:Biomass; D050260:Carbohydrate Metabolism; D002708:Chlorella / Q000254:growth & development* / Q000378:metabolism*; D008027:Light; D050356:Lipid Metabolism; D009584:Nitrogen / Q000378:metabolism; D058433:Photobioreactors / Q000382:microbiology*
chemical_list: D009584:Nitrogen