Determination of UV Phototransformation of DOM in Treated Drinking Water by 3D Fluorescence Aaron D. Dotson 1*, Katherine Beggs 2 and Drew VonLindern 1 1 University of Alaska Anchorage, Civil Engineering & Applied Environmental Science & Technology * addotson@uaa.alaska.edu 2 Cadmus Group
Process Background Ultraviolet Disinfection & Oxidation Physical/Chemical Process UV absorbing species DNA & Proteins (disinfection) Inorganics (advanced oxidation) Dissolved Organic Matter (phototransformation)
UV in the Conventional WTP Coagulant Chlorine Fluoride Raw Water Sand Distribution System 1. Particles Present 2. Higher DOC 3. Trace Organics Present 1. Minimal Particles 2. Lower DOC 3. Some Trace Organics Removed UV Light
UV Lamp Selection
Process Monitoring UV Disinfection Biodosimetry Radiometry Native species (e.g. DOM) UV Advanced Oxidation Active chemicals (e.g. H 2 O 2 ) Scavengers (e.g. pcba) Trace Species (e.g. PPCPs) Native species (e.g. DOM)
WaterRF 4019 Shah et al., 2011 Dotson et al., 2010 Metz et al., 2011 Focus on DOM Monitoring Transformation of DOM Disinfection By-products Disinfection Limited impact on regulated DBPs Increased emerging DBPs Advanced Oxidation with H 2 O 2 Significant increases regulated DBPs Increases in emerging DBPs
LC-MS DOM Reconfiguration MPUV produced greater spectra changes than LPUV Suggests Photo-Fries reaction Benzophenone linkage converted to phenol plus ester linkage Supports increased DBP formation Magnuson et al., 2002
Focus on Fluorescence Perkin Elmer LS55b EX:200-400 nm (5 nm steps) EM:290-450 nm (0.5 nm steps) 290 nm cut-off filter Slit Width 10 nm Auto Excitation Correction Emission Correction by BAM Dyes Inner Filter Correction* 5 Component PARAFAC model** *Gauthier et al., 1986, **Stedmon & Bro, 2008
Experimental Ultraviolet Disinfection & Oxidation UV Collimated Beam* 2 Lamps - LP and MP 4 Doses - 40, 186, 300, 1000 mj/cm 2 8 Drinking Water Samples 7 - Conventionally Treated 1 Conv. + GAC Treated *Bolton & Linden, 2003
Results & Discussion Water Quality Sample TOC mg/l UVA 254 cm -1 NO 3 mg-n/l Alk mg-caco 3 /L Fe μg/l Cu μg/l Al μg/l Ohio River WTP+GAC, OH 0.86 0.016 0.684 54 WTP, CO 1.24 0.023 NA < 5 31.0 2.2 13.5 Ohio River WTP, OH 1.51 0.035 0.671 55 Lake Havasu, AZ 2.24 0.035 0.113 119 13.8 2.8 17.5 Boulder Res., CO 2.26 0.043 NA 47 13.6 2.8 17.5 Lake Pleasant, AZ 2.53 0.037 BDL 121 23.2 2.7 23.1 Saguaro Lake, AZ 3.86 0.078 0.051 128 Bartlett Lake, AZ 5.10 0.067 BDL 190 15.5 2.8 58.1 Ohio River samples omitted from PARAFAC creation
Results & Discussio`n Bulk Parameters No change in TOC Reduction in UVA 254 Increased Humification Index (HIX)
Before UV 1000 mj/cm 2 MPUV Visually apparent changes in EEM due to UV photolysis
Results & Discussion Humic-like PARAFAC Protein-like
Results & Discussion Protein-like Comps. MPUV affects protein-like components more than LPUV #3 C/C 0 #4 C/C 0
Results & Discussion Humic-like Components Comp #1 most affected C/C 0 #1 MPUV treatment results in greater EEM changes C/C 0 #2 #5 C/C 0
Results & Discussion Unique WTPs
Results & Discussion Unique WTPs
Challenges below 240 nm Energy u = hc/λ (Plank s Law) Lower wavelength, higher energy! Organics C, OH or other radicals Inorganics C, OH or other radicals
Nitrate and UV light
Experiment: HA + NO3 + UV Filtered Aldrich Humic Acid UVA 254 0.1 cm -1 Nitrate added as sodium nitrate Photolysis examined insitu (instrument)
Excited NOM? (500 nm/min) Humic Acid starting scan at 200nm Humic Acid starting scan at 240nm Spectra 1 Spectra 2 = Output Spectra EEM Unaffected 240nm signal > 200nm signal 200nm signal > 240 signal
Excited Nitrate? (500 nm/min) Humic Acid starting scan at 200nm 10mg-N/L starting scan at 200nm Spectra 1 Spectra 2 = Output Spectra EEM Affected! 10mg-N/L signal > Humic Acid signal Humic Acid signal > 10mgN/L signal
Summary & Conclusions Phototransformation of DOM can be observed by Fluorescence at low UV doses Photopolymerization (e.g. dimers) or molecular rearrangment can include creation of humic-like fluorescence Scanning below 240 nm may be OK if nitrate is not present Excessive nitrate may hinder EEM regardless region scanned
Thank you! Aaron D. Dotson, Ph.D., P.E. addotson@uaa.alaska.edu (907) 786-6041 Civil Engineering Department and Applied Environmental Science & Technology Program
WaterRF 4019 Impact of UV location and sequence on byproduct formation References Shah, A.D., Dotson, A.D., Linden, K.L., Mitch, W.A. 2011. Impact of UV disinfection combined with chlorination/chloramination on the formation of halonitromethanes and haloacetonitriles in drinking water. Environmental Science and Technology. Dotson, A.D., Keen, V.S., Metz, D., Linden, K.G. 2010. UV/H2O2 treatment of drinking water increases post-chlorination DBP formation. Water Research. 44. 3703-3713 Metz, D., Meyer, M., Dotson, A. Beerendonk, E., Dionysiou, D.D. 2011. The effect of UV/H2O2 treatment on disinfection byproduct formation potential under simulated distribution system conditions. Water Research. 45. 3969-3980. Gauthier, T.D., Shane, E.C., Guerin, W.F., Seitz, W.R., Grant, C.L. 1986. Fluorescence quenching method for determining equilibrium constants for polycyclic aromatic hydrocarbons binding to dissolved humic materials. Environmental Science and Technology. 20. 1162-1166. Magnuson, M.L., Kelty, C.A., Sharpless, C.M. Linden, K.G., Fromme, W., Metz, D.H., Kashinkunti, R. 2002. Effect of UV irradiation on organic matter extracted from treated ohio river water studied through the use of electrospray mass spectrometry. Environmental Science and Technology. 36. 5252-5260. Bolton, J.R., Linden, K.G. 2003. Standardization of methods for fluence (UV Dose) determination in bench-scale UV experiments. Journal of Environmental Engineering. 129:3 (209) Stedmon, C., Bro, R. 2008. Characterizing dissolved organic matter fluorescence with parallel factor analysis: a tutorial. Limnology and Oceanography: Methods. 6. 572-579