title: Ozone regeneration of granular activated carbon for trihalomethane control.
abstract: Spatial and temporal variations of trihalomethanes (THMs) in distribution systems have challenged water treatment facilities to comply with disinfection byproduct rules. In this study, granular activated carbon (GAC) and modified GAC (i.e., Ag-GAC and TiO2-GAC) were used to treat chlorinated tap water containing CHCl3(15-21μg/L), CHBrCl2(13-16μg/L), CHBr2Cl (13-14μg/L), and CHBr3(3μg/L). Following breakthrough of dissolved organic carbon (DOC), GAC were regenerated using conventional and novel methods. GAC regeneration efficiency was assessed by measuring adsorptive (DOC, UV absorbance at 254nm, and THMs) and physical (surface area and pore volume) properties. Thermal regeneration resulted in a brief period of additional DOC adsorption (bed volume, BV, ∼6000), while ozone regeneration was ineffective regardless of the GAC type. THM adsorption was restored by either method (e.g., BV for ≥80% breakthrough, CHBr3∼44,000>CHBr2Cl ∼35,000>CHBrCl2∼31,000>CHCl3∼7000). Cellular and attached adenosine triphosphate measurements illustrated the antimicrobial effects of Ag-GAC, which may have allowed for the extended THM adsorption compared to the other GAC types. The results illustrate that ozone regeneration may be a viable in-situ alternative for the adsorption of THMs during localized treatment in drinking water distribution systems.
authors.affiliation: Southern Nevada Water Authority (SNWA), P.O. Box 99954, Las Vegas, NV 89193-9954, United States. Electronic address: xuexiang.he@lvvwd.com.
authors.forename: Xuexiang
authors.initials: X
authors.lastname: He
authors.affiliation: University of Nevada, Las Vegas, Department of Civil and Environmental Engineering and Construction, Las Vegas, NV 89154, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Elkouz
authors.affiliation: Southern Nevada Water Authority (SNWA), P.O. Box 99954, Las Vegas, NV 89193-9954, United States.
authors.forename: Mandu
authors.initials: M
authors.lastname: Inyang
authors.affiliation: Southern Nevada Water Authority (SNWA), P.O. Box 99954, Las Vegas, NV 89193-9954, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Dickenson
authors.affiliation: Southern Nevada Water Authority (SNWA), P.O. Box 99954, Las Vegas, NV 89193-9954, United States. Electronic address: eric.wert@snwa.com.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Wert
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D054879:Halogenation; D010126:Ozone / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D022882:Trihalomethanes / Q000737:chemistry* / Q000302:isolation & purification; D014867:Water; D014871:Water Microbiology; D018508:Water Purification
chemical_list: D022882:Trihalomethanes; D014867:Water; D002606:Charcoal; D010126:Ozone
keywords: Granular activated carbon (GAC); Ozone; Regeneration; Silver; Trihalomethanes (THMs)