Changes in dissolved organic matter and oxygen consumption in different bank filtration simulations at different scales

Abstract

Both concentrations and compositions of dissolved organic matter (DOM) and the availability of oxygen affect transformation processes in close-to-nature drinking water treatments such as bank filtration and artificial groundwater infiltration. This study focused on quantitative and qualitative analyses of DOM in different saturated sand column systems of different dimensions, histories and operating conditions using fluorescence spectroscopy. The study revealed the presence of two fluorescent DOM (fDOM) fractions (humic-like compounds) through parallel factor analysis (PARAFAC). DOM, fDOM and specific UV absorbance (SUVA) at 254 nm were reduced and correlated in indoor systems. In outdoor columns, the removals of DOM and fDOM were comparably high, but the increased SUVA indicated an increase in aromaticity. Dissolved oxygen consumption corresponded to organic content in sand, independent of residence times. Overall, bank filtration is an effective option to remove biodegradable DOM under outdoor natural conditions.