Formation of disinfection by-products in the ultraviolet/chlorine advanced oxidation process.
Disinfection by-product (DBP) formation may be a concern when applying ultraviolet light and free chlorine (UV/chlorine) as an advanced oxidation process (AOP) for drinking water treatment, due to typically large chlorine doses (e.g. 5-10 mg L(-1) as free chlorine). A potential mitigating factor is the low chlorine contact times for this AOP treatment (e.g. seconds). Full-scale and pilot-scale test results showed minimal trihalomethane (THM) and haloacetic acid (HAA) formation during UV/chlorine treatment, while dichloroacetonitrile (DCAN) and bromochloroacetonitrile (BCAN) were produced rapidly. Adsorbable organic halide (AOX) formation was significant when applying the UV/chlorine process in water that had not been previously chlorinated, while little additional formation was observed in prechlorinated water. Chlorine photolysis led to chlorate and bromate formation, equivalent to approximately 2-17% and 0.01-0.05% of the photolyzed chlorine, respectively. No perchlorate or chlorite formation was observed. During simulated secondary disinfection of AOP-treated water, DBP formation potential for THMs, HAAs, HANs, and AOX was observed to increase approximately to the same extent as was observed for pretreatment using the more common AOP of UV combined with hydrogen peroxide (UV/H2O2).
Department of Civil Engineering, University of Toronto, 35. St. George St., Toronto, Ontario M5S 1A4, Canada. Electronic address: dingwork.wang@mail.utoronto.ca.
Ding
D
Wang
Bolton Photosciences Inc., 628 Cheriton Cres., NW, Edmonton, AB T6R 2M5, Canada.
James R
JR
Bolton
Department of Civil Engineering, University of Toronto, 35. St. George St., Toronto, Ontario M5S 1A4, Canada.
Susan A
SA
Andrews
Department of Civil Engineering, University of Toronto, 35. St. George St., Toronto, Ontario M5S 1A4, Canada.
Ron
R
Hofmann
D002713:Chlorine / Q000737:chemistry; D004202:Disinfectants / Q000032:analysis* / Q000737:chemistry; D004203:Disinfection / Q000379:methods; D006861:Hydrogen Peroxide / Q000737:chemistry; D008956:Models, Chemical; D010084:Oxidation-Reduction; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
D004202:Disinfectants; D014874:Water Pollutants, Chemical; D002713:Chlorine; D006861:Hydrogen Peroxide
Advanced oxidation; Chlorine; Disinfection by-product; Formation potential; UV