Printed in Great Britain Peraamon Press plc USE OF MODIFIED CLAYS FOR THE REMOVAL AND DISPOSAL OF C I I LORINATED DIOXINS AND OTHER PR IORITY POLLUTANTS FROM INDUSTRIAL WASTEWATERS.

The dynarnics of adsorption and elution of octachlorodibenzodioxin (OCDD) on modified clay adsorbents has been studied. In batch type experiments, a rapid approach to sorption equilibrium (within hours) as well as a Freudlich type sorption isotherm were noted. In packed bed sorption experiments using a step input of adsorbate concentratiot~, no breakthrough was observed under a variety of volumetric flow rates suggesting multilayer adsorption of dioxins on modified clay sorbents.Elution f sorbed dioxin with carrier solvent etrahydrofuran (THF) exhibited two peaks indicating heterogeneity of modified clay sorbents. Finally, successive sorption/elution/sorption experiments revea[ that modified clay sorbents can be regenerated and reused. Our previous work had clearly established t/tat chemically modified clays are exu'emety suitable for efficient sorption of trace levels of toxic organics uch as PCDDs and other priority pollutants in wastewaterstreams(1,4). Since uhimate destruction of these toxic organics is currently accepted as an environmentally desirable goal, a full scale development of wastewater t eatment technology has to necessarily include an intermediate pre-concentration step. This i