AWWA ACE58245

This study evaluated the potential of ozone-assisted biofiltration (OAB) for removing taste and odor (T&O) compounds. OAB is a two-step process. In the first step, ozone is added to breakdown the natural organic matter (NOM) into bioassimilable organic carbon. In the second step, biologically active filters are used to oxidize the bioassimilable organic carbon. Pilot testing of OAB was conducted at the Chandler Water Treatment Plant in Arizona as part of an American Water Works Association Research Foundation (AWWARF) study. In these pilot studies, granular activated carbon (GAC)/sand and anthracite/sand media were evaluated parallely. To reduce removal by adsorption, exhausted GAC was used in the GAC pilot filters. The results showed higher 2-methyl isoborneol (MIB) removals in filters with GAC/sand media compared to anthracite/sand. The MIB removals were a function of empty-bed contact time (EBCT); higher MIB removals were observed in filters with higher EBCTs. Most of the MIB removal occurred in the top few inches of the filters indicating predominance of biological oxidation in the upper layers of the media. Increasing ozone dose resulted in slightly enhanced MIB removal. The GAC/sand filters outperformed anthracite/sand filters in terms of total organic carbon (TOC) and UV254 reductions. Higher heterotrophic plate counts (HPCs) were observed in GAC/sand filters compared to anthracite/sand filters indicating higher bioactivity in GAC/sand filters. Both GAC/sand and anthracite/sand filters produced water with turbidities less than 0.2 NTU. Includes 5 references, figures.