Water reuse in hydroponic systems: a realistic future scenario for Germany? Facts and evidence gained during a transdisciplinary research project

The HypoWave transdisciplinary research project investigated the innovation of water reuse in a hydroponic system, focusing on its applicability in Germany. The methods applied were the operation of a pilot plant for the appropriate treatment and subsequent reuse of water in a hydroponic system, expert interviews, feasibility studies, an impact assessment and a stakeholder dialogue. To identify the concept's advantages and disadvantages, publications specialising in the various disciplines involved and meeting protocols were analysed and the results grouped together in a SWOT (strengths, weaknesses, opportunities and threats) analysis. This revealed that the system has potential for application in Germany subject to certain requirements being met, such as suitable local wastewater treatment conditions and actors looking for new business opportunities within agricultural production. This system is not recommended for the country as a whole, but it does offer an interesting alternative for locations that meet the appropriate conditions. Nevertheless, additional efforts and knowledge are required to promote and operate a new system of this kind. These include the reliable supply of irrigation water with guaranteed plant nutrition, comprehensive quality management to manage potential risks, a good understanding of the cooperation arrangements required and a more detailed examination of energy aspects.