Sustainable groundwater management using reclaimed water: the Torreele/St-André case in Flanders, Belgium

The Torreele facility produces infiltration water for indirect potable re-use through artificial recharge of the dune aquifer of St-André. The secondary wastewater effluent is treated by ultrafiltration (UF), using the submerged ZeeWeed system, prior to reverse osmosis (RO), using brackish water low energy membranes. The Torreele experience showed that combining UF and RO enables the treatment of wastewater effluent in an effective and reliable way; RO being the major and ultimate barrier against both microbial and chemical contamination. The produced filtrate is of excellent quality and enables sustainable groundwater management in an area with high ecological interest. The biggest challenges for the Torreele facility are the changing conditions, based on the meteorological and seasonal variations, the scaling and fouling problem and the concentrate. Bio-fouling is prevented by monochloramination and scaling by dosing of antiscalant combined with pH adjustment. The Intermunicipal Water Company of the Furnes Region (IWVA) studied alternative treatment, mainly using natural systems, with the objective to mitigate the impact of the concentrate disposal into surface water and to reduce the charges set for this disposal. Concerning groundwater recharge, IWVA is studying alternatives to optimize the infiltration capacity.