P-Toluenesulfonate in Landfill Leachates: Leachability from Foundry Sands and Aerobic Biodegradation

Abstract

p-Toluenesulfonate (pTS) was found at concentrations between 9.6 and 48.8 mg/L in leachates from two Swiss landfill sections where foundry wastes are stored. pTS represented ≤33% of the nonpurgable organic carbon (NPOC) in the leachates. A standard test showed that pTS is easily leached from foundry sands that contained 1% (w/w) of a technical hardener consisting of tolu enesulfonates. Hence, the hardener is a likely source of pTS in the landfill leachates. Furthermore, analyses using liquid chromatography coupled to mass spectrometry and UV absorption detection indicated that the hardener also was the source for toluene-2,4-disulfonate, benzenesulfonate and o- and m-toluenesulfonate, all of which were detected in the landfill leachates. Modified OECD screening tests with pure pTS or hardener as carbon source and landfill leachate as inoculum indicated that aerobic bacteria using pTS for growth are present in the landfill leachates. The intermediates p-sulfobenzyl alcohol and p-sulfobenzoate gives strong evidence for a degradation pathway common to Comamonas testosteroni.