PRODUCTION AND REMOVAL OF ASSIMILABLE ORGANIC-CARBON UNDER PILOT-PLANT CONDITIONS THROUGH THE USE OF OZONE AND PEROXONE

Pilot-plant studies were conducted in two source waters to determine the effects of predisinfection with ozone alone and with a combination of hydrogen peroxide and ozone (PEROXONE) on the production of assimilable organic carbon (AOC) compounds. Colorado River water (CRW) and State project water (SPW) from Northern California were treated with ozone alone at applied dosages ranging from 1 to 4 mg/L and with PEROXONE at hydrogen peroxide/ozone (H2O2/O3) ratios of 0.05, 0.10, 0.20, and 0.30. Ozonation of CRW with applied dosages of 1.0, 2.0, and 4.0 mg/L increased AOC concentrations from 70 mug C/L to 275, 350, and 224 mu C/L, respectively. Ozonation of SPW with an applied dosage of 4.0 mg/L elevated AOC concentrations from 70 to 522 mug C/L. In most cases, application of PEROXONE at an H2O2/O3 ratio of 0.05 increased production of AOC by up to 100% in comparison with the use of ozone alone; however, there was no clear relationship between PEROXONE ratios and AOC concentrations. Subsequent filtration through biologically active, dual-media anthracite/sand filters reduced AOC concentrations to levels that were lower than or equal to source - water AOC levels. Continuous chloramination at a dosage of 1.5 mg/L across the filters decreased AOC removal efficiency by 80%, indicating that biological activity is required for AOC reduction. Changing the application points of ozone from prefiltration to post-filtration resulted in at least threefold AOC increases over influent values for both source waters. Similar AOC increases were observed when the treatment process was altered to include both prefiltration and post-filtration ozone application. This indicates that even after biological filtration, there may be sufficient organic material remaining to produce AOC upon ozone or PEROXONE disinfection.