Advanced Technologies for Algae Harvesting and Extraction

There are significantly different approaches available for getting chemicals of interest from algae.  These include “milking,” in which the algae are induced into excreting the chemical of interest.  This requires monoculture maintenance and extraction technology from the growth medium.  Another approach is pyrolysis in the presence of an appropriate catalyst to produce a feedstock of interest.  This approach modifies the chemical composition into one that is easier to process using conventional means.  The approach followed in this work, however, harvests and dewaters the algae, lyses it electromagnetically, and separates out the chemicals of interest leaving uncontaminated water and residual biomass.  While there are pre-existing approaches to accomplishing each of these steps, the challenge is to develop technology to do so at a very low cost so that the products produced are commercially competitive.  The research has yielded novel approaches involving chemical modifications, electromagnetic fields, resins, and membranes to produce a system that is effective while likely meeting cost targets.  Mass balance measurements suggest the process is effective with individual steps having 90% or better efficiency.  Development and scaling up the process required the accumulation of better data on the physical and chemical characteristics of the various algae studied.  The processes are being optimized in a pilot process facility that is capable of producing and processing up to about 100 ml of algal oil per week.  This facility permits the selection of algal strains for study, small-scale growth in photobioreactors, larger scale growth in outdoor ponds, harvesting, dewatering, lysing, and separating the algal oil from the water and biomass.  Each step in the process is supported with appropriate measurement technology to characterize the performance of that step.  The system is required as some approaches to reducing cost and improving effectiveness of individual steps can have detrimental effects on system cost and performance.