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Free chlorine is a commonly used disinfectant in drinking water treatment. However, disinfection by-products (DBPs) are formed during water disinfection. Haloacetic acids (HAAs) and trihalomethanes (THMs) are two major groups of DBPs. Iodo-HAAs and iodo-THMs (I-HAAs and I-THMs) are formed during the disinfection of the water containing high levels of iodide and are much more toxic than their chlorinated and brominated analogs. Peracetic acid (PAA) is a strong antimicrobial disinfectant that is expected to reduce the formation of HAAs and THMs during disinfection. In this study, the formations of thirteen HAAs and ten THMs, including the iodinated forms, have been investigated during PAA disinfection and chlorination as the comparison. The DBP formations under different iodide concentrations, pHs, and contact times were systematically investigated. Two types of commercial PAAs containing different concentrations of PAA and hydrogen peroxide (H 2 O 2 ) were studied. A solid-phase microextraction gas chromatography-mass spectrometry method was upgraded for THM analysis including I-THMs. HAAs were analyzed by following a recently developed high performance ion chromatography-tandem mass spectrometry method. Results show that the ratio of PAA and H 2 O 2 concentration significantly affect the formation of I-THMs and I-HAAs. During PAA disinfection with lower PAA than H 2 O 2 , no detectable levels of THMs and HAAs were observed. During PAA disinfection with higher PAA than H 2 O 2 , low levels of monoiodoacetic acid, diiodoacetic acid, and iodoform were formed, and these levels were enhanced with the increase of iodide concentration. No significant quantities of chloro- or bromo-THMs and HAAs were formed during PAA disinfection treatment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation. Using this technique, information regarding NP size, size distribution, particle concentration, and dissolved ion concentrations was obtained simultaneously. The fates of Zn- and Ce-NPs, including those found in river water and added engineered NPs, were evaluated by simulating a typical drinking water treatment process. Lime softening, alum coagulation, powdered activated carbon sorption, and disinfection by free chlorine were simulated sequentially using river water. Lime softening removed 38-53 % of Zn-containing and ZnO NPs and >99 % of Ce-containing and CeO2 NPs. Zn-containing and ZnO NP removal increased to 61-74 % and 77-79 % after alum coagulation and disinfection, respectively. Source and drinking water samples were collected from three large drinking water treatment facilities and analyzed for Zn- and Ce-containing NPs. Each facility had these types of NPs present. In all cases, particle concentrations were reduced by a minimum of 60 % and most were reduced by >95 % from source water to finished drinking water. This study concludes that uncoated ZnO and CeO2 NPs may be effectively removed by conventional drinking water treatments including lime softening and alum coagulation.

One of the most direct means for human exposure to nanoparticles (NPs) released into the environment is drinking water. Therefore, it is critical to understand the occurrence and fate of NPs in drinking water systems. The objectives of this study were to develop rapid and reliable analytical methods and apply them to investigate the fate and transportation of NPs during drinking water treatments. Rapid single particle ICP-MS (SP-ICP-MS) methods were developed to characterize and quantify titanium-containing, titanium dioxide, silver, and gold NP concentration, size, size distribution, and dissolved metal element concentration in surface water and treated drinking water. The effectiveness of conventional drinking water treatments (including lime softening, alum coagulation, filtration, and disinfection) to remove NPs from surface water was evaluated using six-gang stirrer jar test simulations. The selected NPs were nearly completely (97 ± 3%) removed after lime softening and alum coagulation/activated carbon adsorption treatments. Additionally, source and drinking waters from three large drinking water treatment facilities utilizing similar treatments with the simulation test were collected and analyzed by the SP-ICP-MS methods. Ti-containing particles and dissolved Ti were present in the river water samples, but Ag and Au were not present. Treatments used at each drinking water treatment facility effectively removed over 93% of the Ti-containing particles and dissolved Ti from the source water., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Bisphenol A (BPA), bisphenol F (BPF), and bisphenol A diglycidyl ether (BADGE) are common components of epoxy coatings used in food packaging and in drinking water distribution systems. Thus, leachates from the epoxy may be exposed to the disinfectants free chlorine (Cl2/HOCl/OCl(-)) and monochloramine (MCA, NH2Cl). Bisphenols are known endocrine disrupting chemicals (EDC) with estrogenic activity. Chlorination by-products have the potential to have reduced or enhanced estrogenic qualities, and are, therefore, of interest. In this work, chlorination reactions for bisphenols and BADGE were explored (via LC/MS/MS) and kinetic modeling (using a pseudo-first order approach) was conducted to predict the fate of these compounds in drinking water. The half-lives of BPA and BPF with 1 mg/L of free chlorine ranged from 3 to 35 min over the pH range from 6 to 11 and the temperature range of 10-25 °C. Half-lives for reactions of BPA and BPF with a nominal MCA concentration of 3.5 mg/L as Cl2 were from 1 to 10 days and were greater at higher pH and lower temperature. Formation of chlorinated bisphenol A by-products was observed during the kinetic studies. BADGE was found unreactive with either oxidant., (Copyright © 2015. Published by Elsevier Ltd.)

The potential occurrences of endocrine-disrupting compounds (EDCs), as well as pharmaceuticals, are considered to be emerging environmental problems due to their persistence and continuous input into the aquatic ecosystem, even at only trace concentrations. This study systematically investigated the oxidative removal of eight specially selected ECDs and pharmaceuticals by comparing their relative reactivity as a function of different oxidative treatment processes (i.e., free chlorine, ozone, monochloramine, and permanganate) under various pH conditions. For the oxidative removal study, EDC and pharmaceutical standards were spiked into both deionized water and natural water, followed by treatment using common oxidants at typical water treatment concentrations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for identification and quantification. The removal efficiency of the EDCs and pharmaceuticals varied significantly between oxidation processes. Free chlorine, permanganate, and ozone treatments were all highly effective at the elimination of triclosan and estrone, while they were not effective for removing ibuprofen, iopromide, and clofibric acid. Monochloramine (at a dose of 3mg/L) was mostly ineffective in eliminating any of the selected EDCs and pharmaceuticals under the tested conditions. pH also played an important role in the removal efficiency of the EDCs and pharmaceuticals during free chlorine, permanganate, and ozone treatments. Additionally, the study identified the oxidation products of triclosan by permanganate, and 2,4-dichlorophenol was identified as the major oxidation product of triclosan by permanganate in drinking water system treatment. Furthermore, 2,4-dichlorophenol was further degradated to 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol and/or 5,6-dichloro-2-(2,4-dichlorophenoxy)phenol. The kinetics for this reaction indicated that the reaction was first order in the drinking water system., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The oxidation of bromoxynil and trifluralin was investigated using ozone (O(3)) and O(3) combined with hydrogen peroxide (H(2)O(2)) in natural waters using batch reactors. The results indicated that these pesticides could not be completely degraded during ozonation, achieving degradation levels lower than 50%. An enhancement of the level of degradation was observed using O(3)/H(2)O(2) process. A biphasic behaviour of O(3) was also observed. Depending on the experimental conditions, the rate constant for O(3) decomposition was estimated to be between 7.4 × 10(-4) s(-1) to 5.8 × 10(-2) s(-1), and 3.2 × 10(-3) s(-1) to 4.2 × 10(-2) s(-1) for bromoxynil and trifluralin samples, respectively. Acute toxicity analysis performed using Microtox(®) showed a decrease in the toxic effects of the samples on the luminescent bacteria during the first few minutes of treatment, followed by an increase of the toxic effects at the end of the reaction for both pesticides. The quantification of oxidation by-products generated during treatment was also addressed. The total molar balances of the degradation by-products versus the initial pesticide concentrations ranged from 60 to 103% under different experimental conditions., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A comprehensive method has been developed and validated in two different water matrices for the analysis of 16 pharmaceutical compounds using solid phase extraction (SPE) of water samples, followed by liquid chromatography coupled with tandem mass spectrometry. These 16 compounds include antibiotics, hormones, analgesics, stimulants, antiepileptics, and X-ray contrast media. Method detection limits (MDLs) that were determined in both reagent water and municipal tap water ranged from 0.1 to 9.9 ng/L. Recoveries for most of the compounds were comparable to those obtained using U.S. EPA methods. Treated and untreated water samples were collected from 31 different water treatment facilities across Missouri, in both winter and summer seasons, and analyzed to assess the 16 pharmaceutical compounds. The results showed that the highest pharmaceutical concentrations in untreated water were caffeine, ibuprofen, and acetaminophen, at concentrations of 224, 77.2, and 70 ng/L, respectively. Concentrations of pharmaceuticals were generally higher during the winter months, as compared to those in the summer due, presumably, to smaller water quantities in the winter, even though pharmaceutical loadings into the receiving waters were similar for both seasons., (© 2010 Elsevier Ltd. All rights reserved.)

Fipronil, a pesticide gaining wide usage, was oxidized with common drinking water treatment disinfectants and oxidants; with a degradate identified using liquid chromatography-mass spectrometry. Oxidants investigated were free chlorine (HOCl/OCl(-)), monochloramine (ClNH(2)), chlorine dioxide (ClO(2)), and permanganate (MnO(4)(-)) at pH 6.6 and 8.6. Free chlorine, chlorine dioxide, and permanganate were reactive with fipronil to various degrees, whereas monochloramine was only marginally reactive. No oxidation products were observed for free chlorine, monochloramine, or chlorine dioxide. Oxidation by permanganate produced an identifiable degradate, fipronil sulfone, which was recalcitrant to further oxidation by permanganate. Fipronil sulfone could, however, be further degraded by free chlorine. Under typical conditions of water treatment, free chlorine was an effective oxidant for fipronil and fipronil sulfone, achieving partial removal at typical conditions. pH effects were observed for free chlorine, chlorine dioxide, and permanganate with more rapid oxidation occurring at pH 8.6 than at pH 6.6.

Currently, herbicides are widely used in various combinations at many stages of cultivation and during postharvest storage. There are increasing concerns about the public health impact of herbicide degradation byproducts that may be present in water bodies used either as drinking water or for recreational purposes. This work investigated the sulfonic acid and oxanilic acid degradation products of metolachlor, alachlor, acetochlor, and propachlor in a variety of water bodies. The objective was to develop a fast, accurate, and easy method for quantitative analysis of herbicide degradation products using liquid chromatography with tandem mass spectrometry without solid phase extraction, but performing levels of detection lower than those obtained in previous studies with solid phase extraction. This research also screened 68 water samples, both untreated source water and treated water, from 34 water treatment plants in Missouri. Finally, it examined seasonal trends in levels of those degradation products by collecting and testing samples monthly. This highly sensitive method can analyze these degradation products to low ng/L levels. The method limit of quantification ranges from 0.04 to 0.05 ppb for each analyte; and quantitative analyses show a precision with RSDs of around 0.6% to 3% in treated water and 2% to 19% in untreated source water. Concentrations of alachlor ESA, acetochlor OA, metolachlor OA, and metolachlor ESA were detected from the Missouri River and the Mississippi River water bodies in summer time. Occurrences of these compounds in treated water samples are all lower than those in the untreated source water samples.

Aqueous degradation rates, which include hydrolysis and epimerization, for chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TET), lincomycin (LNC), sulfachlorpyridazine (SCP), sulfadimethoxine (SDM), sulfathiazole (STZ), trimethoprim (TRM), and tylosin A (TYL) were studied as a function of ionic strength (0.0015, 0.050, or 0.084 mg/L as Na(2)HPO(4)), temperature (7, 22, and 35 degrees C), and pH (2, 5, 7, 9, and 11). Multiple linear regression revealed that ionic strength did not significantly affect (alpha = 0.05) degradation rates for all compounds, but temperature and pH affected rates for CTC, OTC, and TET significantly (alpha = 0.05). Degradation also was observed for TYL at pH 2 and 11. No significant degradation was observed for LNC, SCP, SDM, STZ, TRM, and TYL (pH 5, 7, and 9) under study conditions. Pseudo first-order rate constants, half-lives, and Arrhenius coefficients were calculated where appropriate. In general, hydrolysis rates for CTC, OTC, and TET increased as pH and temperature increased following Arrhenius relationships. Known degradation products were used to confirm that degradation had occurred, but these products were not quantified. Half-lives ranged from less than 6 h up to 9.7 wk for the tetracyclines and for TYL (pH 2 and 11), but no degradation of LIN, the sulfonamides, or TRM was observed during the study period. These results indicate that tetracyclines and TYL at pH 2 and 11 are prone to pH-mediated transformation and hydrolysis in some cases, but not the sulfonamides, LIN nor TRM are inclined to degrade under study conditions. This indicates that with the exception of CTC, OTC, and TET, pH-mediated reactions such as hydrolysis and epimerization are not likely removal mechanisms in surface water, anaerobic swine lagoons, wastewater, and ground water.

Some researches studied the removal of steroid estrogens by enzymatic treatment, however none verified the residual estrogenicity after the enzymatic treatment at environmental conditions. In this study, the residual estrogenic activities of the key natural and synthetic steroid estrogens were investigated following enzymatic treatment with horseradish peroxidase (HRP) and laccase from Trametes versicolor. Synthetic water and municipal wastewater containing environmental concentrations of estrone, 17beta-estradiol, estriol, and 17alpha-ethinylestradiol were treated. Liquid chromatography-mass spectrometry analysis demonstrated that the studied steroid estrogens were completely oxidized in the wastewater reaction mixture after a 1-h treatment with either HRP (8-10 U ml(-1)) or laccase (20 U ml(-1)). Using the recombinant yeast assay, it was also confirmed that both enzymatic treatments were very efficient in removing the estrogenic activity of the studied steroid estrogens. The laccase-catalyzed process seemed to present great advantages over the HRP-catalyzed system for up-scale applications for the treatment of municipal wastewater.

The Trametes versicolor-derived laccase-catalyzed oxidation of natural estrogens (estrone--E1; 17beta-estradiol--E2; and estriol--E3) and a synthetic estrogen (17alpha-ethinylestradiol--EE2) was studied in synthetic water and municipal wastewater to optimize the process for steroid estrogen removal in wastewater. The optimal pH for each studied steroid estrogen oxidation was approximately 6 in synthetic water. This research also focused on the wastewater matrix effect on developed enzymatic treatment. At pH 7.0 and 25+/-1 degrees C, the experiments showed that the laccase-catalyzed system for the removal of steroid estrogens was not significantly affected by the municipal wastewater matrix. Laccase activity of 20 U/ml was sufficient to achieve complete removal of studied steroid estrogens in both synthetic water and municipal wastewater. Moreover, 1-hydroxy-benzotriazole, when used as a mediator, improved laccase-catalyzed system efficiency, thus decreasing the overall cost of the enzymatic system.

The primary objective of our research was to establish the technical feasibility of using the horseradish peroxidase (HRP) enzyme for natural and synthetic estrogens-estrone (E1), 17beta-estradiol (E2), estriol (E3), and 17alpha-ethinylestradiol (EE2)-removal. The effects of temperature and pH on enzymatic treatment kinetics were investigated. Residual estrogen concentrations were quantified by liquid chromatography, coupled with mass spectrometry analysis. In a synthetic solution at pH 7 and 25+/-1 degrees C, the HRP enzyme-catalyzed process was capable of achieving 92-100% removal of E1, E2, E3, and EE2 within 1h of treatment with an HRP activity of 0.017 U/ml. The influence of the pH (5-9) and temperature (5-35 degrees C) on estrogen removal was observed to be significant, with the optimum pH near neutral conditions. The results also showed that wastewater constituents significantly impact the HRP-catalyzed estrogen removal. The experimental research proved that the HRP-catalyzed system is technically feasible for the removal of the main estrogens present in the environment at low concentrations.