Torreele reuse scheme delivers resilience
In 2017 and 2018, Belgium, and more specifically the Western part of Flanders, suffered from two severe drought events concentrated over a short period of time, from April to July in each year. Over these two consecutives events, only 61% and 68% respectively of the normal average rainfall of 213 mm was recorded. This resulted in increases in drinking-water consumption compared to the five previous years of 5.6% in 2017 and 7.2 % in 2018. In July 2018, the Intermunicipal Water Company of the Veurne Region (IWVA) which distributes drinking water in the western part of the Belgian coastal plain, registered its highest daily consumption since 2009 with 20.796 m³/d as opposed to a five-year average of 16.244 m³/d for the month of July.
With 81% of the freshwater used for agricultural, industrial and potable purposes in Europe being abstracted from surface water bodies and groundwater , users of surface water across Europe explicitly expressed their concerns. Since July 2018, the drought led to the issuing of a code “yellow” warning in The Netherlands meaning that the use of water from the river Rhine for agricultural irrigation was restricted . Similar situations occurred in Flanders and other northern European countries such as the UK, Denmark and Sweden . Lower rainfall also resulted in higher groundwater and surface water salinity especially in low-lying land such as the polder areas in the Netherlands and parts of the Flanders. The Dutch drinking-water utility PWN, based in the northern part of the country, had to stop the intake of water from lake Ijssel due to increased salinity. Groundwater levels also declined in many areas and authorities had to put in place various restrictions: e.g. consumers were forbidden to use drinking-water for gardening and washing cars while industries and farmers had to reduce their groundwater abstractions.
Thanks to a combination of tertiary treatment and reuse at the Torreele wastewater treatment plant and subsequent aquifer recharge in the dunes of St-André, IWVA was able to cope with the increased demand for drinking-water. Even during these two drought events, if effluent is available and thus infiltration continues, the groundwater levels are high enough to keep groundwater production feasible. But besides maintaining the production capacity, the quality of the drinking-water is secured by combining water reuse with infiltration.
The IWVA experience demonstrates that water reuse can help mitigating the impact of climate change and the company is planning to increase the infiltration capacity of its Torreele scheme even further. With an increase in the frequency of drought periods, the success of the IWVA site highlights the need for similar projects across Europe to improve water management strategies in water stressed countries and limit future water shortages. Further innovations which allow the subsurface storage of water when available for later recovery and reuse when demand is rising would further enhance the capacity and value of such approaches.
Emmanuel Van Houtte - Geologist, R&D at Intermunicipal Water Company of the Veurne Region (IWVA), Belgium and Water Reuse Europe Board of Directors