title: A comparison of pilot-scale photocatalysis and enhanced coagulation for disinfection byproduct mitigation.
abstract: This study evaluated pilot-scale photocatalysis and enhanced coagulation for their ability to remove or destroy disinfection byproduct (DBP) precursors, trihalomethane (THM) formation potential (FP), and THMs in two Arizona surface waters. Limited photocatalysis (<5 kWh/m(3)) achieved reductions in most of the DBP precursor parameters (e.g., DOC, UV(254), and bromide) but led to increased chlorine demand and THMFP. In contrast, enhanced coagulation achieved reductions in the DBP precursors and THMFP. Extended photocatalysis (<320 kWh/m(3)) decreased THMFP once the energy consumption exceeded 20 kWh/m(3). The photocatalytic energy requirements for THM destruction were considerably lower (EEO=20-60 kWh/m(3)) than when focusing on precursor destruction and THMFP. However, rechlorination increased the total THM (TTHM) concentration well beyond the raw value, thereby negating the energy benefits of this application. Enhanced coagulation achieved consistent 20-30% removals of preformed THMs. Outstanding issues need to be addressed before TiO(2) photocatalysis is considered feasible for DBP mitigation; traditional strategies, including enhanced coagulation, may be more appropriate.
authors.affiliation: National Science Foundation Water Quality Center, Department of Civil and Environmental Engineering, Arizona State University, Tempe, AZ 85287-5306, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gerrity
authors.forename: Brooke
authors.initials: B
authors.lastname: Mayer
authors.forename: Hodon
authors.initials: H
authors.lastname: Ryu
authors.forename: John
authors.initials: J
authors.lastname: Crittenden
authors.forename: Morteza
authors.initials: M
authors.lastname: Abbaszadegan
mesh_terms: D019342:Acetic Acid / Q000302:isolation & purification; D001130:Arizona; D001959:Bromates / Q000302:isolation & purification; D002384:Catalysis; D002712:Chlorides / Q000302:isolation & purification; D003889:Desert Climate; D004203:Disinfection / Q000379:methods*; D054879:Halogenation; D006863:Hydrogen-Ion Concentration; D009391:Nephelometry and Turbidimetry; D010777:Photochemistry; D010865:Pilot Projects; D012965:Sodium Chloride / Q000032:analysis; D022882:Trihalomethanes / Q000302:isolation & purification; D014466:Ultraviolet Rays
chemical_list: D001959:Bromates; D002712:Chlorides; D022882:Trihalomethanes; D012965:Sodium Chloride; D019342:Acetic Acid; C001599:chlorite