Nutrient Removal and Feedstock Potential of Green Alga Grown in Wastewater under Nordic Conditions

Integrating cultivation with wastewater treatment improves the economics of microalgal based biofuel production and allows for the sustainable reuse of nitrogen (N) and phosphorus (P) from waste streams. This was the aim of a research led by Mikael Jämsä from University of Turku in Finland.

His team performed a batch-cultivation of a locally isolated green microalga, UHCC00027, and an indigenous algal-bacterial consortium on screened municipal wastewater in pilot reactors. They then evaluated the growth as well as N and P removal of the microbes. Lipid accumulation and fatty acid composition were also examined. The wastewater treatment performance under cold temperatures, were also tested.

Results revealed that vigorous, temperature-dependent growth of microalgae was the most important factor in the removal of N and P in the wastewater. The studied cultivation strategy and organisms achieved regulatory N and P removal levels.

However, the biodiesel properties of the resulting biomass did not meet international standards due to a high proportion of polyunsaturated fatty acids. More studies are required to increase the quality of the resulting biofuel.