Towards closing water cycles on higher sandy soils in The Netherlands

Why discharge effluent - an always available freshwater source - out of an area where there is increasing need for water? As part of the AquaConnect - A NWO/TTW project program Royal HaskoningDHV and Witteveen+Bos are organizing working sessions for a dozen PhD students from Wageningen University & Research , 荷兰代尔夫特理工大学 , 荷兰特温特大学 and Universiteit van Amsterdam to answer this question. The question was originally asked for by Waterschap Vallei en Veluwe and Vitens drinking water company to address the specific case around the Dutch city of Epe, which is located on the higher sandy soils area (Veluwe).

There the Nereda wastewater treatment technology discharges about 1-2 million m3 per year of high quality effluent (TN<4 mg/l; TP< 0.2 mg/l) to the IJssel lake and ultimately the sea. At the same time Vitens pumps up 6 million m3 per year of ground water a few kilometers away. With ongoing water stress (partly due to climate change) there is an unbalance in the ground water affecting nature which could be overcome by the amount of effluent discharged by the water authority.

In this third integration workshop we are getting closer to what is needed to (partially) close the water cycle and are combining this practical case with the latest outcomes in researches conducted by the PhD students. The idea is to not only use the outcomes and approaches of these sessions for this specific case, but for any cases facing the same opportunities and challenges. Also, we are using a truly multi disciplinary way addressing a variety of items such as: (1) the importance of public opinion, economy and governance related issues ( No?lle Lasseur ), (2), the impact that filtration of effluent may have on the soil and conversion and adsorption of micro pollutants ( Alessia Ore Jill Soedarso ) that thake place. And (3) what are ways to monitor these processes and how can we determine the impact on aquatic life and biodiversity (Jan Specker, Caixia Wei ). Fourth, what is the impact of infiltration on ground water levels and how can models help select storage locations ( Valdrich Fernandes ), as well as (5) how can rainwater harvesting add to more robustness in the water cycle ( Jorn de Vos ). And finally, what kind of additional treatment is needed and can developments in nano filtration be applied ( Tjerk Watt ) or can combinations of natural conveyance and treatment ( Thomas Wagner ) be applied.

In December the second case on water circularity in horticulture (asked for by Glastuinbouw Nederland and Provincie Zuid-Holland ) will be discussed by the other group of PhD students. We look very much forward to this one. Special thanks for guiding us around to Coert Petri , Merijn Schriks , Paul Keizer and of course my co-facilitator Veerle Luimstra !