(704c) Algal Biomass and Lipid Production From Wastewater Using a Phagotrophic Microalga

The use of wastewater to culture microalgae can decrease the cost of microalgal-based biofuel production.  Currently, studies have been focused on using photosynthetic microalgae with wastewater treatment.  However, photosynthetic microalgae have low growth rates and their mass cultivation is limited to low cell concentrations in shallow ponds or complex narrow-diameter tubular photobioreactors due to the light penetration difficulty.  It is also hard to maintain the selected high-lipid strains in open fields.  In this study, we developed a new phagotrophic microalgae-based wastewater treatment process. By using the unique biological characteristic of the microalga with the engineering principles of continuous culture, a microbial population predominated by the microalga cells could be produced through the process. The lipid content of the produced culture was about 40% of its dry weight and could be potentially enhanced to about 80% with additional process manipulation. The cell concentration was not limited by light penetration. The microalga also showed strong ability in removing nutrients from wastewater. This microalgal lipid production process could potentially be incorporated as part of an overall wastewater treatment operation.