A sustainable production of algal biomass integrating wastewater treatment and bioenergy generation

This project aims to demonstrate the feasibility of producing renewable microalgae biomass using as a main nutrient source a secondary wastewater stream. It is planned to purify the wastewater by the growth of algal biomass while producing a feedstock that can be used for the bioenergy sector. If important biomass density is achieved, this strategy will be adopted in a novel process named SunCHem (proposed at the EPFL-PSI SWT group) using hydrothermal treatment of microalgae to produce methane. Wastewater treatment coupled with algal biomass production is particularly suitable for an implementation in Colombia as it requires low capital investment and it allows the generation of added-value through the valorization of the biomass. In addition, the climatic conditions in Colombia (high annual solar irradiance) are favorable to the installation of this highly ecological sound process. This concept may be interesting to municipal utilities, industrial companies and agricultural firms, since it helps to solve many of their pollution issues. In a preliminary study it was demonstrated the efficient nutrient removal by Dunaliella salina microalgae using a primary treated wastewater effluent1. This microalgae strain reduced the nitrate and phosphate load in the wastewater at 84% and 90% respectively and its specific growth rate of 0.46 d-1 was comparable with that achieved using a standard nutrient media (0.47 d-1). We are currently comparing the ability of three microalgae (Chlorella, Scenedesmus and Ankistrodesmus) strains to remove nitrogen and phosphorus in a conventional media. These three microalgae were selected due to an appropriate carbon balance for their future hydrothermal conversion into methane.