AWWA JAW26065

Experiments were conducted in virgin granular activated carbon (GAC) columns supplied with treated surface water and the synthetic organic chemicals (SOCs) phenol and 2,4-dichlorophenol (DCP). The surface water was subjected to one of three chemical treatments: chlorination, no oxidant addition, or ozonation. The GAC columns were seeded only with microorganisms that passed through conventional treatment. The main objective was a determination of the time required to initiate significant biodegradation of trace concentrations of SOCs. The impact of naturally occurring organic compounds and the type of pretreatment on biodegradation were also of interest, as was biodegradation of sorbed SOCs. Significant biodegradation of phenol and DCP in the liquid phase commenced after one month of operation in columns with contact times of <1 min. Sorbed phenol was biodegraded to a large extent, whereas biodegradation of sorbed DCP was negligible. Total organic carbon removal across the GAC columns was dependent on chemical pretreatment. Ozonation caused an increase in microbial activity in comparison to no oxidant addition, but this did not provide improved removal of DCP. Includes 22 references, tables, figures.