Assessment of key biological and engineering design parameters for production of Chlorella zofingiensis (Chlorophyceae) in outdoor photobioreactors

Peter E. Zemke, Milton R. Sommerfeld, Qiang Hu

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)5645-5655
Number of pages11
JournalApplied Microbiology and Biotechnology
Issue number12
StatePublished - Jun 2013


  • Biochemical composition
  • Chlorella zofingiensis
  • Flat plate photobioreactor
  • Initial concentration
  • Optical path length
  • Photobioreactor orientation

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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