In the past decades microalgae have been viewed as a promising source of sustainable biomass, because the cultivation of microalgae does not require arable land. Because the main use of the biomass has been envisaged as feedstock for biofuel, research has been directed on increasing the (lipid) yield of monospecies. However, because the production of biofuel from such virgin biomass is not economically viable, the production of the biomass should be coupled with other processes. In addition, cultivating polycultures may yield more biomass, while ensuring a stable culture. In this research