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 phthalic acid are some of the factors that could influence the degradation of phthalic acid esters (PAEs). To assess the importance of these factors, the degradation of butyl 2-ethylhexyl phthalate (BEHP), bis(2-ethylhexyl) 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 stimulated by the addition of a PAE known to be degradable. The investigation strongly indicates that water solubility is a major factor limiting degradation of hydrophobic PAEs. In the study conducted, PAEs having high water solubility (DBP, BBP, BEHP, and DHP) were degraded, whereas those having low water solubility were not (DEHP, DOP, and DDP). The investigation also showed that all alcohols, commonly used in PAEs, were degraded to methane and carbon dioxide. It also seems possible that anaerobic degradation of persistent PAEs may be stimulated by organisms in cultures degrading less resistant phthalates.