Modeling reactive transport of reclaimed water through large soil columns with different low-permeability layers

摘要: The efficacy of different proportions silt-loam/bentonite mixtures overlying a vadose zone in controlling solute leaching to groundwater was quantified. Laboratory experiments were carried out using three large soil columns, each packed with 200-cm-thick riverbed covered by 2-cm-thick bentonite/silt-loam mixture as the low-permeability layer (with bentonite mass accounting for 12, 16 and 19 % total mixture). Reclaimed water containing ammonium (NH4 +), nitrate (NO3 −), organic matter (OM), various types phosphorus other inorganic salts applied inflow. A one-dimensional mobile–immobile multi-species reactive transport model used predict preferential flow typical pollutants through columns. simulated results show that is able such conditions. Increasing amount improves removal NH4 + phosphorous (TP) because longer contact time increased adsorption capacity. OM mainly attributed biodegradation. increase TP NO3 − concentration from discharge nitrification soils, respectively. This study underscores role layers barriers protection. Neglect fingers or may cause underestimation pollution risk.