The SUBSOL project - bringing coastal SUBsurface water SOLutions to the market - concluded with a final seminar on coastal water supply and reuse on Wednesday August 29 and a site visit to the ASR reuse facility Dinteloord on Thursday August 30. The seminar brought together reuse experiences from the SUBSOL project, the European Union’s policies and reuse agenda, and experiences from end-users within and outside of Europe.
International guests dr. Walter Daesslé (UABC, Mexico) and Suzana Gico Montenegro (UFPE, Brazil) provided an overview of developments in subsurface storage and water reuse in Baja California, Mexico and Recife, Brazil. While the need and interest for water reuse for agriculture is high in Mexico, pilot applications are delayed due to strict regulations for subsurface infiltration of reuse water. Water quality of the infiltrated water needs to comply to drinking water standards, even before infiltration. In Recife, Brazil, rain water harvesting and infiltration pilots are on the agenda, to counteract seawater intrusion and aquifer salinization. Policy wise, thoughts arise to couple groundwater abstraction rights to obligation to infiltrate harvested rainwater.
Dr. Koen Zuurbier (KWR, the Netherlands) and dr. Alexander Vandenbohede (De Watergroep, Belgium) presented reuse applications for agriculture and drinking water, respectively. Wastewater from the food industry is reused as irrigation water by local greenhouse farmers in Dinteloord, after balancing water supply (autumn – winter) and demand (spring – summer) with aquifer storage and recovery (ASR). The Dinteloord ASR reuse facility has helped the local farmers through the exceptional warm and dry summer of 2018. Despite having a mild, relatively wet climate, water shortages in Belgium are high. One of the reasons, is that natural recharge of aquifers (i.e. rainwater infiltration) is limited because of the local geology (thick clay layers overlaying deeper aquifers). Drinking water company De Watergroep is therefore looking for alternative water resources, including reuse water. Managed aquifer recharge (MAR) is viewed as a crucial step in the treatment process to produce high-quality drinking water.
The seminar concluded with a round-table discussion on water reuse practice and policies, moderated by Paul Jeffrey (Cranfield University, UK; Water Reuse Europe). Subsurface storage may help catalyze water reuse, yet current legislation often impedes promising applications, both in Europe and internationally. Policy making is an elaborate process and it is therefore that legislation may lag behind technical innovations. It is thus crucial to actively involve policy makers and other stakeholders in water reuse R&D, such that questions and issues related to policy and regulations are addresses from the very beginning, including field piloting.