AWWA JAW28824

Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalomethanes and their precursors) and to analyze means of employing PAC more efficiently. Background information discusses characteristics of PAC and factors affecting its performance. The extent of adsorption of synthetic organic chemicals on PAC is strongly dependent on the type of compound being removed. The reported removals of trihalomethanes and trihalomethane precursors by PAC range from poor to very good. In selecting the point of addition of PAC, consideration must be given to the degree of mixing, the contact time between the PAC and the water, the PAC residence time, and the minimization of interference of adsorption by treatment chemicals and calcium carbonate; various techniques for improving adsorption efficiency are described. One of the main advantages of PAC is its low capital cost. A full report of this project, "Control of Organic Compounds with Powdered Activated Carbon," is published by AWWA, order number 90581. Includes 74 references, tables.