The Reactivity of Dissolved Organic Matter for Disinfection By-Product Formation

Dissolved organic matter (DOM) in 6 water samples collected from 4 surface waters were fractionated using some or all of 5 physicochemical separation processes (activated carbon and XAD-8 batch adsorption, alum coagulation, ultrafiltration (UF), and XAD-8 column fractionation). Activated carbon, XAD-8 batch adsorption and alum coagulation processes fractionated DOM by preferentially removing high-SUVA components from solution. The XAD-8 column method fractionated DOM into hydrophobic and hydrophilic components while UF separated DOM into different size fractions. Over 40 DOM fractions, characterized using carbon-normalized (specific) ultraviolet absorbance (SUVA), were obtained for each water. Trihalomethane (THM) and haloacetic acid (HAA_9) formation after chlorination was quantified for each fraction. For each natural water, a strong correlation was observed between the SUVA values of DOM fractions and their THM and HAA_9 formations, independent of the separation processes used to obtain the fractions. Therefore, the correlation obtained for each water appears to represent its natural disinfection by-product (DBP) reactivity profile. However, SUVA is not a universal predictor of DOM reactivity because a unique DBP reactivity profile was obtained for each water tested. The distribution of SUVA within a source water and its relationship to reactivity were found to be more informative than the source water aggregate SUVA value. Individual DBP species also correlated well with the SUVA of DOM fractions in a single water. Formation of trichloroacetic acid (TCAA) was dominant over dichloroacetic acid (DCAA) for high-SUVA fractions, whereas the formation of TCAA and DCAA was comparable for low-SUVA fractions

Formation of disinfection by-products in indoor swimming pool water: The contribution from filling water natural organic matter and swimmer body fluids

The contribution and role of different precursors in the formation of three class of disinfection by-products (DBPs) [trihalomethanes (THMs), haloacetic acids (HAAs), and halonitromethanes (HNMs)] in swimming pool waters were examined using filling waters obtained from five drinking water treatment plant (WTP) effluents and three body fluid analogs (BFAs). BFAs exerted higher chlorine demands as compared to natural organic matter (NOM) in filling waters. BFAs exhibited higher HAA formation potentials than THM formation potentials, while the opposite was observed for the filling water NOM. There was no appreciable difference in the HNM formation potentials of BFAs and filling water NOM. Different components in the BFAs tested exhibited different degree and type of DBP formation. Citric acid had significantly higher THM and HAA yields than other BFA components. The effect of temperature was greater on THM formation, whereas the effect of contact time had more impact on HAA formation. Experiments with filling waters collected from WTP effluents at three different times showed more variability in HAA than THM formation at the WTPs studied

Estimation of haloacetonitriles formation in water: Uniform formation conditions versus formation potential tests

HANs formation from five different chlorinated water sources were higher under UFC than FP tests. • Chlorination FP tests do not provide meaningful information for HAN precursors in water samples. • UFC (or SDS) chlorination test should be used for a better estimation of HAN precursors in water. • Higher HANs formed under FP test compared to UFC test during chloramination. • Chloramination FP tests may be used for determining HAN precursors in water reactive to chloramine.To date, several studies have used formation potential (FP) tests to examine the presence of HAN precursors in water and wastewater. However, given the decomposition of HANs with time at elevated free chlorine levels, FP test results do not provide meaningful results.Weconducted side-by-side FP and uniform formation condition (UFC) experiments to demonstrate that, in order to obtain practical, meaningful, and representative information about HANs formation and their precursors during chlorination, it is important to conduct experiments and report results under UFC [or simulated distribution system (SDS)] conditions. The results confirmed higher HAN formation under UFC than FP tests during chlorination of the tested two surface water and three wastewater effluent samples, indicating HAN decomposition at high chlorine conditions of FP tests. In addition, thewell reported ratio (~10%) of HAN/THMfrom previous studies was more consistentwith the UFC results but was lower than 10% in the FP results. On the other hand, HAN formation during chloramination of the same samples were lower under the UFC than FP conditions. Furthermore, FP tests under both chlorination and chloramination resulted in lower bromine substitution factor. We concluded that reporting results of HANs FP tests are not representative, and future studies should focus on UFC or distribution system specific (SDS) experiments for chlorination. However, chloramination FP tests may still provide some information about the HAN precursors in waters

Removal of the precursors of regulated DBPs and TOX from surface waters and wastewater effluents using mixed anion exchange resins

Mixed and single anion exchange resins were tested for the removal of organic and inorganic DBPs precursors from water. Formation of total organic halides (TOX) was more reduced from wastewater effluents treated by the mixed resin system. Doubling the resin dose resulted in less than 10e20% improvement in DBP precursors’ removal.Both organic and inorganic precursors play important roles in the formation and speciation of disinfection by-products (DBPs). This study aimed to investigate the efficacy of three different anion exchange resins for removing both organic and inorganic DBP precursors simultaneously in a single treatment system. Resins in the single (Purolite®-Br, MIEX®-Br, and MIEX®-Gold) and mixed (Purolite®-Br with MIEX®-Gold and MIEX®-Br with MIEX®-Gold) application modes were tested and compared for the removal of dissolved organic carbon (DOC), bromide (Br ), and iodide (I ) from a raw source water and a treated wastewater effluent. Uniform formation condition (UFC) tests were conducted to measure the concentrations of trihalomethanes (THM4), haloacetic acids (HAA9), haloacetonitriles (HAN6), and total organic halides (TOX): total organic chlorine (TOCl), total organic bromine (TOBr), and total organic iodine (TOI) before and after the anion exchange resin treatments. The anion exchange treatment substantially lowered the DOC, UV254 absorbing matter, dissolved nitrogen (DN), Br , and I . Consequently, the formation of THM4, HAA9, HAN6, and TOX in the examined chlorinated water samples were reduced significantly. The maximum reduction in THM4 and TOX (66e69% and 61%, respectively) from wastewater effluent was achieved by the mixed resin system, which also reduced the THM4 and TOX by 77% and 77%, respectively, from raw source water. Overall, mixed resin systems (a DOC-selective and a Brselective resin) resulted in lower amounts of THM4 and HAA9 formation during subsequent chlorination with lower bromine incorporation as compared to single resin systems. Furthermore, they exhibited lower TOBr formation, while TOI formation was not detecte

Occurrence and Formation of Disinfection By-Products in Indoor US Swimming Pools

Chlorination is commonly used to prevent the spreading of waterborne infectious diseases in swimming pools. This required disinfection practice also results in the formation of undesirable disinfection by-products (DBPs) from the reactions of chlorine with the organic matter (released by swimmers or present in the pool filling water) and inorganics (i.e., bromide). The main objective of this research was to improve our understanding of the occurrence and formation of different classes of DBPs (trihalomethanes [THMs], haloacetic acids [HAAs], halonitromethanes [HNMs], haloacetonitriles [HANs], and nitrosamines) in indoor swimming pools operational conditions in the U.S.. The results showed that the DBPs in the investigated 23 swimming pools were far higher than the drinking water regulation values in the U.S. Average THMs, HAAs, HANs, HNMs, and N-nitrosodimethylamine concentrations were 80 μg/L, 1541 μg/L, 19 μg/L, 5.4 μg/L, and 27 ng/L, respectively. An increase in organic matter released by the swimmers and bromide (from the filling water or electrochemical generation of chlorine) levels in the water increased the overall formation of DBPs. Increases in free available chlorine, pH, and water temperature were shown to enhance the formation of THMs and HAAs. These favorable conditions lead to rapid formation (i.e. 3-6 hours) of THMs and HAAs under swimming pool conditions

Formation of Halonitromethanes and Iodo-Trihalomethanes in Drinking Water Summary

The main purpose of this study was to examine the conditions and precursors involved in the formation of two emerging classes of disinfection by-products (DBPs), halonitromethanes (HNMs) and iodo-trihalomethanes (I-THMs), which are not currently regulated but have been observed in some drinking water systems

Impacts of dissolved oxygen on the sorption of humic substances and the subsequent inhibition of o-cresol ptake by granular activated carbon

The impacts of dissolved oxygen (DO) on the sorption of natural and model humic substances by granular activated carbon (GAC) were investigated. Among five substances tested, the sorptions of only two, polymaleic acid (PMA) and peat humic acid, were affected by the presence of DO. The uptake of the target compound o-cresol on virgin GAC and on GAC preloaded with PMA under oxic and anoxic conditions was also examined. The oxic and anoxic preloading conditions had similar effects on subsequent o-cresol reactions under both oxic and anoxic sorption conditions. A reduction of approximately 20 % in o-cresol uptake observed under anoxic conditions by GAC preloaded under each condition is attributed to a decrease in the adsorption capacity of the GAC by preloading. In the presence of oxygen, however, an observed reduction of about 45% in o-cresol uptake by preloaded GAC appears to result from a combination of decreased adsorption and inhibited o-cresol polymerization.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31488/1/0000410.pd

Predictive modeling of haloacetonitriles under uniform formation conditions

Highlights • HAN model linearity is highly affected by water type • pH is the most influential parameter for HAN modeling for chlorination and chloramination • A positive correlation between DON/DOC term and HANs models was observed in EfOM impacted waters • The r2 of DCAN model in chlorination (r2=0.88) was higher than chloramination (r2=0.49) • Higher correlation between HAN4 and THM4 was found at pH range of 7 to 8The objective of this study was to develop models to predict the formation of HANs under uniform formation conditions (UFC) in chlorinated, choraminated, and perchlorinated/chloraminated waters of different origins. Model equations were developed using multiple linear regression analysis to predict the formation of dichloroacetonitrile (DCAN), HAN4 (trichloroacetonitrile [TCAN], DCAN, bromochloroacetonitrile [BCAN], and dibromoacetonitrile [DBAN]) and HAN6 (HAN4 plus monochloroacetonitrile, monobromoacetonitrile). The independent variables covered a wide range of values, and included ultraviolet absorbance, dissolved organic carbon, dissolved organic nitrogen, SUVA254, bromide, pH, oxidant dose, contact time, and temperature. The r2 values of HAN4 and HAN6 models of NOM, AOM, and EfOM impacted waters were within the range of 60-88%, while the r2 values of HAN4 and DCAN models for both groundwater and distribution systems were lower, in the range of 41-66%. The r2 values for the DCAN model were mostly higher in the individual types as compared to the cumulative analysis of all source water data together. This was attributed to differences in HAN precursor characteristics. For chlorination, among all variables, pH was found to be the most significant descriptor in the model equations describing the formation of DCAN, HAN4, and HAN6, and it was negatively correlated with HAN formation in the distribution system, groundwater, AOM, and NOM samples, while it showed an inverse relationship with HAN6 formation in effluent organic matter (EfOM) impacted waters. During chloramination, pH was the most influential model descriptor for DCAN formation in the NOM. Prechlorination dose was the most predominant parameter for prechlorination/chloramination, and it was positively correlated with HAN4 formation in AOM impacted waters

Coagulation-Ceramic Membrane Filtrati on for U.S. Surface Water Treatment Summary

The objective of this project was to conduct a systematic pilot-scale investigation of a hybrid coagulation-ceramic membrane treatment system to gain fundamental insights about necessary pretreatment conditions, fouling mechanisms, and contaminant removal capabilities, using two U.S. surface water sources. A two-phase plan was implemented for each of the three coagulants considered in this study: aluminum sulfate, aluminum chlorohydrate, and ferric chloride. The first phase involved the optimization of the coagulation pretreatment conditions that provided the best performance in terms of particle removal, organics removal, and membrane fouling. The second phase involved a comprehensive performance evaluation of the optimized system. The removal of precursors of selected regulated and emerging disinfection by-products as well as selected microorganisms and surrogates from the two U.S. surface waters was determined

Trihalomethane hydrolysis in drinking water at elevated temperatures

a b s t r a c t Hydrolysis could contribute to the loss of trihalomethanes (THMs) in the drinking water at elevated temperatures. This study was aimed at investigating THM hydrolysis pertaining to the storage of hot boiled water in enclosed containers. The water pH value was in the range of 6.1e8.2 and the water temperature was varied from 65 to 95 C. The effects of halide ions, natural organic matter, and drinking water matrix were investigated. Results showed that the hydrolysis rates declined in the order following CHBrCl 2 > CHBr 2 Cl > CHBr 3 > CHCl 3 . THM hydrolysis was primarily through the alkaline pathway, except for CHCl 3 in water at relatively low pH value. The activation energies for the alkaline hydrolysis of CHCl 3 , CHBrCl 2 , CHBr 2 Cl and CHBr 3 were 109, 113, 115 and 116 kJ/mol, respectively. No hydrolysis intermediates could accumulate in the water. The natural organic matter, and probably other constituents, in drinking water could substantially decrease THM hydrolysis rates by more than 50%. When a drinking water was at 90 C or above, the first order rate constants for THM hydrolysis were in the magnitude of 10 À2 -10 À1 1/h. When the boiled real tap water was stored in an enclosed container, THMs continued increasing during the first few hours and then kept decreasing later on due to the competition between hydrolysis and further formation. The removal of THMs, especially brominated THMs, by hydrolysis would greatly reduce one's exposure to disinfection by-products by consuming the boiled water stored in enclosed containers. © 2015 Published by Elsevier Ltd. Introduction Chemical disinfection acts as the cornerstone unit operation of water treatment processes that secure drinking water safety w a t e r r e s e a r c h 7 8 ( 2 0 1 5 ) 1 8 e2 7 http://d