Isolation of microalgae with potential for integrated biomass production and nutrient removal from wastewater

The study first investigates the diversity of microalgae in the constructed wetland. Then one of the potential microalgal species was isolated and cultivated in photoautotrophic and mixotrophic growth conditions to compare the performance on biomass production and to evaluate the ability of wastewater treatment and simultaneous biodiesel production. Scenedesmus sp. was an abundant strain in the constructed wetland during 1 year of monitoring. Under both photoautotrophic and mixotrophic cultivation conditions, an appropriate composition of each source was beneficial for respective biomass production, 8% (v v(-1)) CO2 and 40% piggery wastewater content. The specific growth rate and lipid productivity obtained from photoautotrophic growth were slightly higher than those obtained from mixotrophic growth. Both cultivation conditions led to different fatty acid compositions. Comparing the photoautotrophic and mixotrophic growth, the mixotrophic cultivation not only produced biomass but also could assimilate up to 81.5% total nitrogen (TN), 64.6% total phosphorous (TP), and 60.7% chemical oxygen demand (COD) from piggery wastewater, respectively. The highest biomass productivity was observed at 16.9:1.1:1 of COD/TN/TP of piggery wastewater.