Direct measurement and characterization of active photosynthesis zones inside wastewater remediating and biofuel producing microalgal biofilms

• Published in: Bioresource technology 2014-03, Vol.156, p.206-215
• Main Authors: Bernstein, Hans C., Kesaano, Maureen, Moll, Karen, Smith, Terence, Gerlach, Robin, Carlson, Ross P., Miller, Charles D., Peyton, Brent M., Cooksey, Keith E., Gardner, Robert D., Sims, Ronald C.
• Format: Article
• Language: English
• Subjects: Aerobiosis; Algae; Applied sciences; Biodegradation, Environmental; Biofilm; Biofilms; Biofilms - growth & development; Biofuel; Biofuel production; Biofuels - microbiology; Biological and medical sciences; Biomass; Bioreactors - microbiology; Biotechnology; Energy; Esters - metabolism; Exact sciences and technology; Fuels; Fundamental and applied biological sciences. Psychology; Heterogeneity; Industrial applications and implications. Economical aspects; Microalgae; Microalgae - physiology; Nitrogen - deficiency; Oxygen - analysis; Photosynthesis; Pollution; Respiration; Waste water; Waste Water - microbiology; Wastewater remediation; Wastewaters; Water Purification - methods; Water treatment and pollution
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2014.01.001

•Microalgal biofilm formation at lab- and field-scale.•Biofilm composition and orientation influence photosynthesis and respiration.•Decrease in localized O2 may improve photosynthetic biofilm technologies.•Biofilm systems produced biofuel precursor molecules.•Nitrogen depletion did not result in drastic triacylglycerol accumulation. Microalgal biofilm based technologies are of keen interest due to their high biomass concentrations and ability to utilize light and CO2. While photoautotrophic biofilms have long been used for wastewater remediation, biofuel production represents a relatively new and under-represented focus area. However, the direct measurement and characterization of fundamental parameters required for industrial control are challenging due to biofilm heterogeneity. This study evaluated oxygenic photosynthesis and respiration on two distinct microalgal biofilms cultured using a novel rotating algal biofilm reactor operated at field- and laboratory-scales. Clear differences in oxygenic photosynthesis and respiration were observed based on different culturing conditions, microalgal composition, light intensity and nitrogen availability. The cultures were also evaluated as potential biofuel synthesis strategies. Nitrogen depletion was not found to have the same effect on lipid accumulation compared to traditional planktonic microalgal studies. Physiological characterizations of these microalgal biofilms identify fundamental parameters needed to understand and control process optimization.