Characterization of dissolved organic matter from surface waters with low to high dissolved organic carbon and the related disinfection byproduct formation potential
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Journal of Hazardous Materials 271 (2014) 228235
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Journal of Hazardous Materials
journa l homepage: www.e lsev ier .com/ locate / jhazmat
haracterization of dissolved organic matter from surface waters withow to high dissolved organic carbon and the related disinfectionyproduct formation potential
ngzhen Lia,b, Xu Zhaoa,, Ran Maoa, Huijuan Liua, Jiuhui Qua
State key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085,hinaChina Academy of Urban Planning and Design, Beijing 100044, China
i g h l i g h t s
The DBPFP of source waters did notcorrelate with the DOC value.SUVA didnt represent the potentialto form DBP in low-aromatic waters.The Hi fraction played an importantrole in DBPFP for waters.Phenolic hydroxyl group tended toform TCM and TCAA during chlorina-tion.Carboxyl and alcoholic hydroxylgroups tended to form DCAA andBr-DBP.
g r a p h i c a l a b s t r a c t
The characterization of DBP precursors from three sourcewaters in China revealed that theDBPFP did notcorrelatewith theDOC value. TheHo fractionmainly contained phenolic hydroxyl and conjugated doublebonds which were reactive with chlorine to produce DBP, especially TCM and TCAA. The Hi fraction maycontainmore amino, carboxyl and alcoholic hydroxyl groups,which had the great potential to formDCAAand Br-DBP during chlorination.
r t i c l e i n f o
rticle history:eceived 24 November 2013eceived in revised form 27 January 2014ccepted 7 February 2014vailable online 16 February 2014
eywords:isinfection byproductissolved organic carbon
a b s t r a c t
In this study, the disinfection byproduct formation potential (DBPFP) of three surface waters with thedissolved organic carbon (DOC) content of 2.5, 5.2, and 7.9mg/L was investigated. The formation anddistribution of trihalomethanes and haloacetic acids were evaluated. Samples collected from three sur-face waters in China were fractionated based on molecular weight and hydrophobicity. The raw watercontaining more hydrophobic (Ho) fraction exhibited higher formation potentials of haloacetic acid andtrihalomethane. The DBPFP of the surface waters did not correlate with the DOC value. The values ofDBPFP per DOC were correlated with the specific ultraviolet absorbance (SUVA) for Ho and Hi fractions.The obtained results suggested that SUVA cannot reveal the ability of reactive sites to form disinfectionydrophobicityhlorination
byproducts for waters with few aromatic structures. Combined with the analysis of FTIR and nuclearmagnetic resonance spectra of the raw waters and the corresponding fractions, it was concluded thatthe Ho fraction with phenolic hydroxyl and conjugated double bonds was responsible for the production
of trichloromethanes and trichpotential to form dichloroacet
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ttp://dx.doi.org/10.1016/j.jhazmat.2014.02.009304-3894/ 2014 Published by Elsevier B.V.loroacetic acids. The Hi fraction with amino and carboxyl groups had theic acids and chlorinated trihalomethanes.
2014 Published by Elsevier B.V.
@163.com (R. Mao), email@example.com (H. Liu), firstname.lastname@example.org (J. Qu).
A. Li et al. / Journal of Hazard
It is recognized that dissolved organic matter (DOM) is therincipal precursor of disinfection byproducts (DBPs) in the chlo-ination treatment [1,2]. Trihalomethanes (THMs) and haloaceticcids (HAAs) are the two major groups of DBPs, which are poten-ially carcinogenic [3,4]. Therefore, it is important tounderstand theelationship between the characteristics of DOM and DBPs yields.
To understand the composition of DOM in surface water, DOMas been isolated and fractionated by ultrafiltration and resin frac-ionation according to the molecular weight and physicochemicalroperties . The hydrophobic fraction with large moleculareight DOM was found to be the most important source of DBPsrecursors [8,10]. Hydrophilic fraction may also contribute sub-tantially to the formation of DBPs especially in waters with lowumic component . Moreover, it was found that the character-stics of natural organic matter (NOM) in surface water dependedn climate, geological conditions and surrounding watersheds1214]. Although some studies were performed to characterizeOM in several source waters [12,14,15], little information wasocused on the composition and characteristics of DBPs precur-ors in different regions of China, especially for the individualtructure of DBPs precursors in waters with high concentration ofromide.A different formation trend of THMs and HAAs in the chlori-
ation treatment was reported [3,16]. The presence of bromiden DOM also had an effect on the formation and distributionf THMs and HAAs during the chlorination process [8,17]. Sev-ral researchers have tried to correlate water quality parameters,uch as dissolved organic carbon (DOC) and specific ultravioletbsorbance divided by dissolved organic carbon (SUVA) to disin-ection byproduct formation potential (DBPFP) of DOM [3,10,18].UVA has been found to be a good indicator for quantifying NOMeactivity in DBPs formation [3,7]. By contrast, Ates et al. reportedhat SUVA did not correlate well with the formation and species ofBPs in waters with low DOC content . Thus, it was requiredhat an integrated analytical approach to elucidate the chemicalomposition and physical structures of DBPs precursors.
The primary aim of this research was to compare the char-cteristics of DBPs precursors from three water sources in Chinaontaining low to high DOC levels. The effectiveness of SUVA valuen predicting DBPs formation with different bromide, SUVA andOC levels was investigated. The raw waters and the correspond-ng fractions were examined for their associated functional groupsy three dimensional excitation-emissionmatrix (3DEEM) fluores-ence, fourier transform infrared (FT-IR) and 13C nuclear magneticesonance (13C NMR) spectra analysis. Relationship between thetructures of DBPs precursors and DBPs species was explored.
. Materials and methods
.1. Raw water sampling
The rawwaterswere collected from three potablewater sourcesetweenOctober2011and July2012. Thewater sourceswereas fol-ows:Miyun Reservoir (Beijing (BJ), northern China),Weishan LakeXuzhou (XZ), east China), and Hongze Lake (Lianyungang (LYG),ast China). Sampleswere collected in 25 Lplastic bottles anddeliv-red to the laboratory. After being filtrated by a pre-rinsed 0.45mlass fiber filters, the samples were stored in the dark at 4 C..2. Resin and membrane separation of the DOC fractions
NOMwas fractionated into five fractions using a stirred ultrafil-ration cell device (Model 8200, Amicon, Millipore) with nominalaterials 271 (2014) 228235 229
molecular weight cutoffs of 3, 10, 30, and 100kDa regenerated cel-lulose membranes (PL, 63.5mm, Millipore). Experiments followedtheproceduredescribedbyKitis et al. (2002).Meanwhile, NOMwasalso fractionated by resin fractionation. The filtered NOMwas acid-ified to pH2 using 6M sulfuric acid and then passed throughDAX-8resin followed by XAD-4 resin, in accordance with the method ofAiken et al. (1992). Effluent from the XAD-4 resin was collectedand named as the hydrophilic (Hi) fraction. The hydrophobic (Ho)and transphilic (Hs) fractions were retained by DAX-8 and XAD-4 resin (Supelco, Bellefonte, PA, USA) respectively. These fractionswere eluted with 0.1M sodium hydroxide in the reverse direction.The Ho and Hs fractions were concentrated again on the MSC-Hcation exchange resin obtained from J&K in order to remove thesalt of the Ho and Hs fractions. Each NOM fraction was diluted tooriginal state with ultrapure water and the pH value was adjustedto be 7.00.2 using H2SO4 or NaOH. The DOC concentration andthe UV absorbance at 254nm (UV254) of each NOM fraction weremeasured.
2.3. DBPs formation potential
Chlorination experiment was carried out according to the Stan-dard Method 5710 with modifications . As described in theStandard Method 5710B, the reaction time for THMFP shouldbe 7 days. However, it is also described in 5710D that for somecompounds, such as brominated haloacetic acids, are not stableand can degrade during storage-either during a long reaction time,7daysmaybe too long for somecompounds. TheNaOCl stock solu-tion (20mg/mL as Cl2) was stored in aluminum foil-covered glassstoppedflask. Chlorine dosing solutionwas prepared from the dilu-tion of NaOCl stock solution (about 5mg/mL as Cl2). NaOH/KH2PO4buffer solutions (pH7.0) and chlorine dosing solutionwere injectedinto each sample. The chlorine dosewas determined by 4h prelim-inary demand tests on each sample according to Standard Method5710B . After being dosed with chlorine, samples were storedat 252 C in the dark for 24h. Free chlorine residuals of the sam-plesweremeasured by anN,N-diethyl-p-phenylenediamine (DPD)titrimetricmethod . After the addition of the sodiumsulfite intothe water samples, the concentrations of trihalomethanes forma-tion potential (THMFP) and haloacetic acids formation potential(HAAFP) wer