Microalgal biorefinery:Biofilm photo-reactor and extraction methods
Natural Sciences and Engineering Research Council of Canada
- Grant type: Strategic Projects - Group
- Years: 2010/11 to 2012/13
- Total Funding: $230,000
Microalgal technologies, used as a method of conversion of (sun)light to liquid fuels, hold several advantages over conventional crops: they can produce up to 100 times more biomass per unit of crop area; the lipid content of this biomass can be up to 70% (dry basis); the doubling time can be in the order of few days; and they can grow in aggressive environments, including saline or even alkaline waters. Despite all these advantages, biodiesel produced using current microalgal cultivation and processing technology is not economic. Most of the costs are associated with various separation and extraction steps that have not been addressed. Furthermore, a "biorefinery" (multi-product) approach to microalgae processing could significantly improve the overall process economics. To address these issues we propose the use of a microalgal biofilm technology whereby microalgae will grow in photoreactors packed with a fibrous substrate (large area to volume ratios). By simple changes in the feed to the reactor we plan to evaluate various aqueous extraction techniques, ranging from aggressive alkaline emulsions (designed to break the cell walls and extract all the biomass) to mild non-toxic microemulsion solvents used to "milk" (extract high value-added lipids without killing the cells) the microalgae. Further to lipid extraction, we plan to introduce membrane-based separations of proteins and carbohydrates that can be used for food and bio-fuel production. Our two industrial partners, Biox and Ocean Nutrition, are interested in high quality, low cost lipids for fuel and food production, respectively. They will be involved in the development of the separation technologies and assessing the value of the extracted lipids as feedstock in their respective processes. Further to the production of biomass for food and fuels, the proposed biofilm reactors will also be used in combination with treated wastewater to further reduce costs and and reduce nutrient discharges to the environment. Due to the large surface area to volume ratio, close control of temperature and gas transfer, the biofilm reactor is expected to occupy a relatively small foot print, and therefore be suitable for use in industrial and municipal settings in Canada.