In the last years the research on algae cultivation as well as algae production for food and feed additives, cosmetics, pigments and 3rd generation biofuels increased in Europe, and especially in Lower Austria, where five companies have been active in this field. As algae production has a high water demand, sustainable handling of water resources is indispensable. In the scientific community little information is available on recycling of algae process water. In specific, a lack of information exists on the determination of soluble components in algae process water and their effect on algae growth. For this reason, the main aim of this project, which will be conducted in cooperation of BIOENERGY 2020+, BOKU IFA-Tulln and Ecoduna, is to save fresh water and reduce waste water production by recycling process water. Overall, the results gained within this project will ensure an effective and sustainable handling of water at algae cultivation, helping Lower Austria to keep its lead in the fields of clean water resources, good water treatment as well as algae research and production.