Treatment of wastewater and associated gaseous emission is costly and technically challenging. With increasingly stringent regulations and limits on wastewater discharge and gaseous emission, modification of conventional processes must be made to meet these requirements. These process modifications will require substantial capital investment and would also likely substantially increase operating costs. The present proposed study takes a creative approach in which microalgae is grown on nutrients supplied from wastewater and gaseous emission from wastewater treatment plants, harvested and extracted for oil that is converted to biodiesel fuel, and the remaining algal biomass can be used for ethanol and biooil production. This would create a win-win situation where water and air conditions are improved while renewable energy is generated. The goal of our research is to develop technologies to produce high oil content microalgae in large scale. We studied the growth of selected microalgae species on tap water and wastewater with or without supplemental nutrients and CO₂ inputs. Different batch and continuous bioreactors and harvest techniques were evaluated. The biomass yield, oil yield, and nutrient removal ability of micro-algae in responses to the wastewaters at different treatment stages under different lighting conditions were investigated. The experimental results showed that 70% of nitrate and phosphate ions in sewage can be effectively removed after six days of algae culture. Dry biomass production reached at 0.25-0.5g /L/day. The technical and economic implications of our results for wastewater treatment and biomass production will be discussed.

Keywords: bioenergy; microalgae culture; wastewater; toxicity; growth inhibition; biomass; biodiesel