INFLUENCE OF WATER SOLUBILITY, SIDE-CHAIN DEGRADABILITY, AND SIDE-CHAIN STRUCTURE ON THE DEGRADATION OF PHTHALIC-ACID ESTERS UNDER METHANOGENIC CONDITIONS

Water solubility and the degradability of side chains estrifying phtha lic acid are some of the factors that could influence the degradation of phthalic acid esters (PAEs). To assess the importance of these fact ors, the degradation of butyl 2-ethylhexyl phthalate (BEHP), bis(2-eth ylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), dihexyl phthalate (DHP), dioctyl phthalate (DOP), and didecyl phthalate (DDP) as well as the alcohols estrifying these PAEs was examined using a methanogenic butylbenzyl phthalate (BBP)-degrading enrichment culture. We also set out to determine whether the degradation of resistant PAEs could be st imulated by the addition of a PAE known to be degradable. The investig ation strongly indicates that water solubility is a major factor limit ing degradation of hydrophobic PAEs. In the study conducted, PAEs havi ng high water solubility (DBP, BBP, BEHP, and DHP) were degraded, wher eas those having low water solubility were not (DEHP, DOP, and DDP). T he investigation also showed that all alcohols, commonly used in PAEs, were degraded to methane and carbon dioxide. It also seems possible t hat anaerobic degradation of persistent PAEs may be stimulated by orga nisms in cultures degrading less resistant phthalates.