Two 6.3 l/sec (0.15 mgd), two-stage, packed-bed, downflow granular activated carbon pilot plants were operated continuously for 33 months using unfiltered and unchlorinated activated sludge plant effluent. The main objective of the study was to compare the performance of granular carbons of different particle size. The data collected during this study has demonstrated the efficacy of the two stage carbon adsorptive system in consistently producing effluent of excellent overall quality. Effluent averaged 6-7 mg/l DCOD and 2 mg/l S.S. The carbon capacity with the 8x30 mesh carbon decreased about 25% after four adsorption cycles, resulting in an apparent steady state capacity of 0.26 lbs. DCOD removed/lb carbon. A 23% decrease in carbon capacity occurred after three adsorption cycles with the 12x40 mesh carbon. The 12x40 carbon has about 13% more DCOD removal capacity than the 8x30 carbon. While the smaller carbon showed slightly higher treatment capacity than the larger carbon, the latter has lower initial cost, lower pressure loss and lower regeneration loss. Thus the larger size carbon was more economical.

"Submitted by the Los Angeles County Sanitation Districts ... in fulfillment of Contract Number 14-12-150 under the sponsorship of the Environmental Protection Agency"--Page iv "September 1978"--Cover "EPA-600/2-78-170"--Cover "Project Officer Irwin J. Kugelman Wastewater Research Division Municipal Environmental Research Laboratory." Includes bibliographical references. Sponsored by the Environmental Protection Agency Contract Number: 14-12-150