Evaluation of an inactivation procedure for determining the sorption of organic compounds to activated sludge

A batch method was developed and validated for determining the sorption coe fficient (K-d) of biodegradable organic compounds to activated sludge solid s using a nonspecific analytical technique, total organic carbon (TOC) anal ysis. In this method, activated sludge solids were first inactivated by lyo philization and dry heat (103 degreesC) and then mashed to remote any disso lved organic carbon released during the inactivation procedure. The inactiv ated sludge solids were exposed to a range of concentrations of different t est compounds in synthetic wastewater until equilibrium was achieved (< 2 h ). The amount of test compound sorbed to the solids was then determined by measuring TOC levels in centrifuged supernatants. Results revealed that the sorption coefficients (K-d values) for four detergent chemicals in inactiv ated sludge solids using TOC analysis were in good agreement with values de termined in fresh activated sludge using radiolabeled materials. These K-d values are suitable for use in estimating environmental exposure concentrat ions and for developing screening-level models to assess the removal of org anic compounds by sorption and settling during activated sludge wastewater treatment. (C) 2000 Academic Press.