The overall objective of this program was to evaluate the feasibility of the expanded-bed technique for contacting granular activated carbon with biologically treated sewage effluent, and to provide a rigorous comparison between this technique and the conventional packed-bed mode of operation. The evaluations and comparisons were to be made with pilot scale adsorbers under actual field operating conditions. Although secondary effluent without further pretreatment was of primary interest, the effects of additional clarification were also to be determined. (Modified author abstract)