p-Toluenesulfonate in landfill leachates: Leachability from foundry sands and aerobic biodegradation

p-Toluenesulfonate (pTS) was found at concentrations between 9.6 and 48.8 m g/L in leachates from two Swiss landfill sections where foundry wastes are stored. pTS represented less than or equal to 33% of the nonpurgable organi c 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 toluenesulfonates. Hence, the hardener is a likely source of pTS in the landfill leachates. Furthermore, analyses using liquid chromato graphy coupled to mass spectrometry and UV absorption detection indicated t hat the hardener also was the source for toluene-2,4-disulfonate, benzenesu lfonate and o- and m-toluenesulfonate, all of which were detected in the la ndfill leachates. Modified OECD screening tests with pure pTS or hardener a s carbon source and landfill leachate as inoculum indicated that aerobic ba cteria using pTS for growth are present in the landfill leachates. The inte rmediates p-sulfobenzyl alcohol and p-sulfobenzoate gives strong evidence f or a degradation pathway common to Comamonas testosteroni.