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

Abstract

This work assessed the elimination of dissolved organic matters (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 the GSC involves both electrostatic attraction and ligand exchange reaction. GSC synthesized using the sludge from waterworks is a very promising filler that can be applied in some green infrastructures for removing DOM in the road runoff.