Lipid Production from Algae Grown in Saline Water Using Low Intensity Culture Techniques

Many arid regions of the United States have high levels of incident solar radiation and ample supplies of saline groundwater. This project’s goal was to determine the feasibility of growing algae for lipid production in saline water using low intensity management techniques in the southwestern United States. After preliminary trials, dry matter production, lipid content, lipid production, and lipid characteristics were determined for Chaetoceros gracilis, Monoraphidium sp., Tetraselmis suecica and Navicula sp. to select promising species for pilot scale outdoor trials. Tetraselmis and Chaetoceros exhibited superior performance in these trials.

In outdoor, open tank field trials designed to simulate low intensity management as would be found in farm ponds, Chaetoceros performed poorly and was replaced routinely by “weedy” species. Tetraselmis performed at a satisfactory level, producing approximately 4.5 g-m-2 day-1 ash-free dry material and 0.7 g-m-2 day-1 lipid during a 30-day mid-summer trial. Tetraselmis had only moderate weed resistance and was also replaced by weed algae. A weed alga, strain MA1, produced dry matter and lipid at about the same rate as Tetraselmis.

Unfortunately, these rates are one-third or less of the productivity of intensely managed outdoor algae cultures. It is probable that intensive management techniques will need to be used to justify the capital investment in algae harvesting and lipid processing equipment.