Column studies to assess the effects of climate variables on redox processes during riverbank filtration.

摘要: Riverbank filtration is an established technique used world-wide to produce clean drinking water in a reliable and cost-efficient way. This practice is, however, facing new challenges posed by climate change, as already observed during past heat waves with the local occurrence of anoxic conditions. In this study we investigated effect direct (temperature) indirect (dissolved organic matter (DOM) concentration composition, flow rate) change variables on redox processes (aerobic respiration, denitrification Mn(III/IV)/Fe(III) reduction) means column experiments. Natural river water, modified mixed treated wastewater effluent were feed waters for columns filled natural sand from river-infiltration system Switzerland. Biodegradable dissolved was mainly removed immediately at inlet particulate (POM) associated main electron donor aerobic respiration throughout column. Low infiltration rates (≤0.01 m/h) enhanced oxygen consumption leading DOM did not seem be sensitive temperature, although (i.e., POM degradation) showed strong temperature dependence activation energy ∼70 kJmol(-1). Anoxic conditions developed 30 °C partial formation nitrite ammonium. absence nitrate, Mn(II) mobilized 20 °C, highlighting importance nitrate acting buffer under preventing reductive dissolution Mn(III/IV)(hydr)oxides. Reductive Fe(III)(hydr)oxides these