Présentations Colloques

Clogging represents one key issue during the operation of managed aquifer recharge (MAR), especially relevant when recharging an aquifer with treated wastewater or surface water. The accumulation of suspended solids and biomass in the soil pore space leads to a decrease in the soil hydraulic parameters and hence a performance reduction of infiltration systems. As a result, costly restoration measures need to be applied to recover the infiltration capacity. Minimizing clogging can therefore increase the overall performance and bring down the operative costs of MAR facilities. **The specific objective of this work is to investigate the correlation between clogging formation and operational parameters of surface infiltration systems (hydraulic loading cycle, infiltration rates, water quality) and to identify the optimal boundary conditions at which clogging can be minimized. For this aim, mathematical models were identified which can quantify clogging processes taking place during MAR operation and selected models were applied exemplary for laboratory experiments. **The laboratory set-up consisted of a 3D, rectangular-shaped stainless steel lysimeter (1.5 x 1.0 x 1.0 m) with an infiltration basin (0.45 x 0.3 x 0.06 m) installed in the center of its surface. River water with 25 mg l dissolved organic carbon and 15 mg l total suspended solids was infiltrated in the basin with a hydraulic loading rate of 146 m a and a hydraulic loading cycle of 1-3. The spatial and temporal distribution of soil moisture was measured by an array of tensiometers and TDR probes in two different depths at 0.28 m and 0.68 m below surface. The clogging rate was estimated taking into account tensiometer data and soil water content measurements.**Mathematical models chosen to calculate the clogging rate during the laboratory experiments cover different complexities and range from simple empirical equations to numerical flow and transport modeling. Results of the different models were compared to evaluate which methods work the best for the specific cases studied.