Removal of dissolved organic matter in road runoff by granules prepared using sludge from waterworks

Abstract

This work assessed the elimination of dissolved organic matter (DOM) in road runoff by a granular sludge-clay (GSC) adsorbent. The rates of adsorption were found to be consistent with the pseudo-second-order kinetic model. The data at equilibrium resulted in a maximum adsorption capacity of 4.466 mg/g at 298 K, which was in good agreement with the Langmuir isotherm model. The adsorption of DOM relies on pH. The higher removal efficiency of DOM was observed at pH 4.0 and 7.0. To clarify the related adsorption mechanism, isolated DOM fractions and their removal potentials were identified. The results showed hydrophobic acid (HoA) and hydrophobic neutral (HoN) fractions which contained abundant fulvic-like substances were more preferentially removed by the GSC. The adsorption mechanism of DOM in road runoff by GSC involves both electrostatic attraction and ligand exchange reactions. GSC synthesized using the sludge from waterworks is a very promising filler to replace soils or gravels that can be applied in some green infrastructures for removing DOM from road runoff. HIGHLIGHTS A granular sludge-clay (GSC) adsorbent prepared using sludge from waterworks can effectively remove the DOM in road runoff.; The adsorption of DOM by GSC was highly dependent on pH.; HoA and HoN fractions were more preferentially adsorbed by GSC.; The adsorption mechanism of DOM in road runoff by the GSC involves both electrostatic attraction and ligand exchange reactions.;

Keywords

• adsorption
• dissolved organic matter (dom)
• granular sludge-clay (gsc) adsorbent
• road runoff