AWWA ACE95108

The Contra Costa Water District (C.C.W.D.) has successfully predicted the optimal timing for its Granulated Activated Carbon (GAC) filter changeouts based on a combined program of in-house physical examination of GAC filter media, and analysis of flavor profile panel results, plus customer taste and odor complaints. The District conducted a three year study of the physical aging of the GAC media in its filters. Iodine number determinations, tannin number determinations, apparent density, TOC removal and sieve analysis were all performed in accordance with procedures given in Standard Methods ASTM Standards and AWWA standards for GAC and Powdered Activated Carbon (PAC). Deposition analysis was also done to determine the effects of solids loading on the above parameters. Flavor Profile Analysis (FPA), which utilizes a trained panel to detect the presence and approximate concentrations of odorous compounds in raw and finished waters was also used in this study.