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Different groups of disinfection by-products (DBPs) were studied through the degradation of iopamidol by the sequential oxidation process of ozone-low pressure ultraviolet light (O 3 -LPUV) followed by chlorination. This paper investigates the attenuation of iopamidol under this sequential treatment and the effect of chlorine contact time (30 min versus 3 days) to control the formation potential of DBPs: trihalomethanes (THMs), haloacetonitriles (HANs) and haloacetamides (HAMs). Thirty target DBPs among the 9 iodinated-DBPs (I-DBPs), were monitored throughout the sequential treatment. Results showed that O 3 -LPUV removed up to 99% of iopamidol, while ozone and LPUV alone removed only 90% and 76% respectively. After chlorine addition, O 3 -LPUV yielded 56% lower I-DBPs than LPUV. Increasing chlorine contact time resulted in higher concentrations of all DBP groups (THMs, HANs, and HAMs), with the exception of I-DBPs. One new iodinated-haloacetamide, namely chloroiodoacetamide (CIACM) and one iodoacetonitrile (IACN) were detected. These results suggest the iodine incorporated in iopamidol may be a precursor for iodinated-nitrogenous-DBPs, which are currently not well studied., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This work evaluated different advanced oxidation processes (AOPs) operated at pilot-scale as tertiary treatment of municipal wastewater in terms of energy efficiency, disinfection by-products formation and pathogens inactivation. Investigated AOPs included UV/H 2 O 2 , UV/Cl 2 , O 3 , O 3 /UV, H 2 O 2 /O 3 /UV, Cl 2 /O 3 /UV. AOPs were operated using various ozone doses (1.5-9 mg L -1 ), and UV fluences (191-981 mJ cm -2 ). Electrical energy costs necessary for the oxidation of contaminants of emerging concern (CEC) (i.e., carbamazepine, fluoxetine, gemfibrozil, primidone, sulfamethoxazole, trimethoprim) were calculated using the electrical energy per order (E EO ) parameter. Ozonation resulted by far the most energy efficient process, whereas UV/H 2 O 2 and UV/Cl 2 showed the highest energy costs. Energy costs for AOPs based on the combination of UV and ozone were in the order O 3 /UV ≈ Cl 2 /O 3 /UV > H 2 O 2 /O 3 /UV, and they were significantly lower than energy costs of UV/H 2 O 2 and UV/Cl 2 processes. Cl 2 /O 3 /UV increased bromate formation, O 3 /UV and O 3 had same levels of bromate formation, whereas H 2 O 2 /O 3 /UV did not form bromate. In addition, UV photolysis resulted an effective treatment for NDMA mitigation even in combination with ozone and chlorine in AOP technologies. Ozonation (doses of 1.5-6 mg L -1 ) was the least effective process to inactivate somatic coliphages, total coliform, escherichia coli, and enterococci. UV irradiation was able to completely inactivate somatic coliphages, total coliform, escherichia coli at low fluence (191 mJ cm -2 ), whereas enterococci were UV resistant. AOPs that utilized UV irradiation were the most effective processes for wastewater disinfection resulting in a complete inactivation of selected indicator organisms by low ozone dose (1.5 mg L -1 ) and UV fluence (191-465 mJ cm -2 )., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This work critically compared the removal of fluorescing PARAFAC components and selected pharmaceuticals (carbamazepine, fluoxetine, gemfibrozil, primidone, sulfamethoxazole, trimethoprim) from a tertiary wastewater effluent by different UV- and ozone-based advanced oxidation processes (AOPs) operated at pilot-scale. Investigated AOPs included UV/H 2 O 2 , UV/Cl 2 , O 3 , O 3 /UV, H 2 O 2 /O 3 /UV, and the new Cl 2 /O 3 /UV. AOPs comparison was accomplished using various ozone doses (0-9 mg/L), UV fluences (191-981 mJ/cm 2 ) and radical promoter concentrations of Cl 2  = 0.04 mM and H 2 O 2  = 0.29 mM. Chlorine-based AOPs produced radical species that reacted more selectively with pharmaceuticals than radical species and oxidants generated by other AOPs. Tryptophan-like substances and humic-like fluorescing compounds were the most degraded components by all AOPs, which were better removed than microbial products and fulvic-like fluorescing substances. Removal of UV absorbance at 254 (UV 254 ) nm was always low. Overall, chlorine-based AOPs were more effective to reduce fluorescence intensities than similar H 2 O 2 -based AOPs. The Cl 2 /O 3 /UV process was the most effective AOP to degrade all target micro-pollutants except primidone. On the other hand, the oxidation performance of pharmaceuticals by other ozone-based AOPs followed the order H 2 O 2 /O 3 /UV > O 3 /UV > O 3 . UV/Cl 2 process outcompeted UV/H 2 O 2 only for the removal of trimethoprim and sulfamethoxazole. Correlations between the removal of pharmaceuticals and spectroscopic indexes (PARAFAC components and UV 254 ) had unique regression parameters for each compound, surrogate parameter and oxidation process. Particularly, a diverse PARAFAC component for each investigated AOP resulted to be the most sensitive surrogate parameter able to monitor small changes of pharmaceuticals removal., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Wastewater reclamation has increasingly become popular to secure potable water supply. Low-pressure membrane processes such as microfiltration (MF) and ultrafiltration (UF) play imperative roles as a barrier of macromolecules for such purpose, but are often limited by membrane fouling. Effluent organic matter (EfOM), including biopolymers and particulates, in secondary wastewater effluents have been known to be major foulants in low-pressure membrane processes. Hence, the primary aim of this study was to investigate the effects of pre-ozonation as a pre-treatment for UF on the membrane fouling caused by EfOM in secondary wastewater effluents for hydrophilic regenerated cellulose (RC) and hydrophobic polyethersulfone (PES) UF membranes. It was found that greater fouling reduction was achieved by pre-ozonation for the hydrophilic RC membrane than the hydrophobic PES membrane at increasing ozone doses. In addition, the physicochemical property changes of EfOM, including biopolymer fractions, by pre-ozonation were systemically investigated. The classical pore blocking model and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theories were employed to scrutinize the fouling alleviation mechanism by pre-ozonation. As a result, the overarching mechanisms of fouling reduction were attributed to the following key reasons: (1) Ozone degraded macromolecules such as biopolymers like proteins and polysaccharides into smaller fractions, thereby increasing free energy of cohesion of EfOM and rendering them more hydrophilic and stable; (2) pre-ozonation augmented the interfacial free energy of adhesion between foulants and the RC/PES membranes, leading to the increase of repulsions and/or the decrease of attractions; and (3) pre-ozonation prolonged the transition from pore blocking to cake filtration that was a dominant fouling mechanism, thereby reducing fouling., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Ozone oxidation has been demonstrated to be an effective treatment process for the attenuation of trace organic compounds (TOrCs); however, predicting TOrC attenuation by ozone processes is challenging in wastewaters. Since ozone is rapidly consumed, determining the exposure times of ozone and hydroxyl radical proves to be difficult. As direct potable reuse schemes continue to gain traction, there is an increasing need for the development of real-time monitoring strategies for TOrC abatement in ozone oxidation processes. Hence, this study is primarily aimed at developing indicator and surrogate models for the prediction of TOrC attenuation by ozone oxidation. To this end, the second-order kinetic equations with a second-phase R ct value (ratio of hydroxyl radical exposure to molecular ozone exposure) were used to calculate comparative kinetics of TOrC attenuation and the reduction of indicator and spectroscopic surrogate parameters, including UV absorbance at 254 nm (UVA 254 ) and total fluorescence (TF). The developed indicator model using meprobamate as an indicator compound and the surrogate models with UVA 254 and TF exhibited good predictive power for the attenuation of 13 kinetically distinct TOrCs in five filtered and unfiltered wastewater effluents (R 2 values > 0.8). This study is intended to help provide a guideline for the implementation of indicator/surrogate models for real-time monitoring of TOrC abatement with ozone processes and integrate them into a regulatory framework in water reuse., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Cylindrospermopsin (CYN) is a potent toxic alkaloid produced by a number of cyanobacteria frequently found in lakes and reservoirs used as drinking water sources. We report for the first time detailed pathways for the degradation of CYN by treatment with ozone. This was accomplished by use of ultra-high-performance liquid chromatography (UHPLC)-quadrupole time-of-flight mass spectrometry (QTOF MS), which revealed that CYN is readily degraded by ozone with at least 36 transformation products. Structural similarities among the major products indicated that the carbon-carbon double bond in the uracil ring of CYN was most susceptible to attack by ozone. Furthermore, the nitrogen functionality associated with the tricyclic guanidine moiety is also involved via a degradation pathway that has not been previously observed. To assess the potential toxicity of ozonation products of CYN, the cytotoxicity of CYN and the mixture of its ozonation products was measured in a human hepatoma cell line (HepG2). The IC50 for CYN at 24 and 48 h incubations was approximately 64.1 and 12.5 μM, respectively; however, the ozonation products of CYN did not exhibit measurable cytotoxicity to human cells. The results indicate ozone is an effective and practical method for CYN attenuation in water treatment without formation of overtly toxic transformation products.

N-Nitrosodimethylamine (NDMA) formation by ozonation was investigated in the effluents of four different wastewater treatment plants destined for alternative reuse. Very high levels of NDMA formation were observed in wastewaters from treatment plants non operating with biological nitrogen removal. Selected experiments showed that hydroxyl radical did not have a significant role in NDMA formation during ozonation of wastewater. Furthermore, ozonation of three different polymers used for water treatment, including polyDADMAC, anionic polyacrylamide, and cationic polyacrylamide, spiked in wastewater did not increase the NDMA formation. Effluent organic matter (EfOM) likely reduced the availability of ozone in water able to react with polymers and quenched the produced ·OH radicals which limited polymer degradation and subsequent NDMA production. Excellent correlations were observed between NDMA formation, UV absorbance at 254 nm, and total fluorescence reduction. These data provide evidence that UV and fluorescence surrogates could be used for monitoring and/or controlling NDMA formation during ozonation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Ozone doses normalized to the dissolved organic carbon concentration were applied to the primary influent, primary effluent, and secondary effluent of a wastewater treatment plant producing water destined for potable reuse. Results showed the most N-Nitrosodimethylamine (NDMA) production from primary effluent, and the recycle streams entering the primary clarifiers were identified as the main source of NDMA precursors. The degradation of aminomethylated polyacrylamide (Mannich) polymer used for sludge treatment was a significant cause of precursor occurrence. A strong correlation between NDMA formation and ammonia concentration was found suggesting an important role of ammonia oxidation on NDMA production. During ozonation tests in DI water using dimethylamine (DMA) as model precursor, the NDMA yield significantly increased in the presence of ammonia and bromide due to the formation of hydroxylamine and brominated nitrogenous oxidants. In addition, NDMA formation during ozonation of dimethylformamide (DMF), the other model precursor used in this study, occurred only in the presence of ammonia, and it was attributable to the oxidation of DMF by hydroxyl radicals. Filtered wastewater samples (0.7 μm) produced more NDMA than unfiltered samples, suggesting that ozone reacted with dissolved precursors and supporting the hypothesis of polymer degradation. Particularly, the total suspended solids content similarly affected NDMA formation and the UV absorbance decrease during ozonation due to the different ozone demand created in filtered and unfiltered samples.

Ozonation is effective in improving the quality of municipal wastewater effluents by eliminating organic micropollutants. Nevertheless, ozone process design is still limited by (i) the large number of structurally diverse micropollutants and (ii) the varying quality of wastewater matrices (especially dissolved organic matter). These issues were addressed by grouping 16 micropollutants according to their ozone and hydroxyl radical ((•)OH) rate constants and normalizing the applied ozone dose to the dissolved organic carbon concentration (i.e., g O3/g DOC). Consistent elimination of micropollutants was observed in 10 secondary municipal wastewater effluents spiked with 16 micropollutants (∼2 μg/L) in the absence of ozone demand exerted by nitrite. The elimination of ozone-refractory micropollutants was well predicted by measuring the (•)OH exposure by the decrease of the probe compound p-chlorobenzoic acid. The average molar (•)OH yields (moles of (•)OH produced per mole of ozone consumed) were 21 ± 3% for g O3/g DOC = 1.0, and the average rate constant for the reaction of (•)OH with effluent organic matter was (2.1 ± 0.6) × 10(4) (mg C/L)(-1) s(-1). On the basis of these results, a DOC-normalized ozone dose, together with the rate constants for the reaction of the selected micropollutants with ozone and (•)OH, and the measurement of the (•)OH exposure are proposed as key parameters for the prediction of the elimination efficiency of micropollutants during ozonation of municipal wastewater effluents with varying water quality.

Recent studies have shown that 1H-benzotriazole is a widespread contaminant of wastewater and surface water. Although disinfection by ozone has been shown to efficiently remove this compound, the transformation products have not been identified. To that end, the reaction of ozone with 1H-benzotriazole in aqueous solution has been studied in real time employing quadrupole time-of-flight mass spectrometry (Q-TOF MS) and negative electrospray ionization. The transformation products have been identified by calculating their empirical formulas using accurate mass measurements, and further confirmed by performing the reaction with stable isotope-labeled 1H-benzotriazole and measuring product ion spectra. Stable reaction products were distinguished from transient species by plotting their extracted mass profiles. The products that resulted from ozone and hydroxyl radicals in the reaction were qualitatively identified by modifying the conditions to either promote the formation of hydroxyl radicals, or to scavenge them. Based on experimental evidence, a mechanism for the direct reaction between ozone and 1H-benzotriazole is proposed that results in the formation of 1H-1,2,3-triazole-4,5-dicarbaldehyde, which has an empirical formula of C(4)H(3)O(2)N(3). Lastly, it was confirmed that the same transformation products formed in surface water and tertiary-treated wastewater, although they were observed to degrade at higher ozone doses.

In an effort to validate the use of ozone for contaminant oxidation and disinfection in water reclamation, extensive pilot testing was performed with ozone/H(2)O(2) and biological activated carbon (BAC) at the Reno-Stead Water Reclamation Facility in Reno, Nevada. Three sets of samples were collected over a five-month period of continuous operation, and these samples were analyzed for a suite of trace organic contaminants (TOrCs), total estrogenicity, and several microbial surrogates, including the bacteriophage MS2, total and fecal coliforms, and Bacillus spores. Based on the high degree of microbial inactivation and contaminant destruction, this treatment train appears to be a viable alternative to the standard indirect potable reuse (IPR) configuration (i.e., membrane filtration, reverse osmosis, UV/H(2)O(2), and aquifer injection), particularly for inland applications where brine disposal is an issue. Several issues, including regrowth of coliform bacteria in the BAC process, must be addressed prior to full-scale implementation., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The reduction of ultraviolet (UV) absorbance at 254 nm (UV254) and true color were identified as appropriate surrogates to assess the oxidation of six pharmaceuticals (i.e., carbamazepine, meprobamate, dilantin, primidone, atenolol, and iopromide) during ozonation of wastewater. Three tertiary-treated wastewaters were evaluated during oxidation with ozone (O3) and O3 coupled with hydrogen peroxide (O3/H2O2). The correlation between pharmaceutical oxidation and removal of UV254 was dependent upon the reactivity of each specific compound toward ozone, as measured by the second-order rate constant (k'(O3)). Oxidation of compounds with k'(O3) > 10(3) M(-1) s(-1) correlated well (R2 > 0.73) with UV254 reduction between 0-50%. Oxidation of compounds with apparent k'(O3) < 10 M(-1) s(-1) resulted primarily from hydroxyl radicals and correlated well (R2 > 0.80) with the UV254 reduction of 15-85%. The removal of true color also correlated well (R2 > 0.85) with the oxidation of pharmaceuticals during the ozonation of two wastewaters. These correlations demonstrate that UV254 reduction and true color removal may be used as surrogates to evaluate pharmaceutical oxidation in the presence or absence of dissolved ozone residual during advanced wastewater treatment with O3 or O3/H2O2. The use of online UV254 measurements would allow wastewater utilities to optimize the ozone dose required to meet their specific treatment objectives.

Three tertiary-treated wastewater effluents were evaluated to determine the impact of wastewater quality (i.e. effluent organic matter (EfOM), nitrite, and alkalinity) on ozone (O(3)) decomposition and subsequent removal of 31 organic contaminants including endocrine disrupting compounds, pharmaceuticals, and personal care products. The O(3) dose was normalized based upon total organic carbon (TOC) and nitrite to allow comparison between the different wastewaters with respect to O(3) decomposition. EfOM with higher molecular weight components underwent greater transformation, which corresponded to increased O(3) decomposition when compared on a TOC basis. Hydroxyl radical (()OH) exposure, measured by parachlorobenzoic acid (pCBA), showed that limited ()OH was available for contaminant destruction during the initial stage of O(3) decomposition (t<30s) due to the effect of the scavenging by the water quality. Advanced oxidation using O(3) and hydrogen peroxide did not increase the net production of ()OH compared to O(3) under the conditions studied. EfOM reactivity impacted the removal of trace contaminants when evaluated based on the O(3):TOC ratio. Trace contaminants with second order reaction rate constants with O(3)(k(O)(3))>10(5)M(-1)s(-1) and ()OH (k(OH))>10(9)M(-1)s(-1), including carbamazepine, diclofenac, naproxen, sulfamethoxazole, and triclosan, were >95% removed independent of water quality when the O(3) exposure (integralO(3)t) was measurable (0-0.8mgmin/L). O(3) exposure would be a conservative surrogate to assess the removal of trace contaminants that are fast-reacting with O(3). Removal of contaminants with k(O)(3) < 10M(-1)S(-1) , and k(OH)>10(9)M(-1)s(-1), including atrazine, iopromide, diazepam, and ibuprofen, varied when O(3) exposure could not be measured, and appeared to be dependent upon the compound specific k(OH). Atrazine, diazepam, ibuprofen and iopromide provided excellent linear correlation with pCBA (R(2)>0.86) making them good indicators of ()OH availability.

Although ozone disinfection is a well established technology for drinking water treatment, ozone disinfection mechanisms in wastewater are not well understood such that, historically, ozone wastewater disinfection has not been a feasible technology to implement. The HiPOx system is an ozone-based pressurized in-vessel system that can be used either as an advanced oxidation reactor or as a highly efficient ozone dissolution system. The pilot-scale HiPOx system was temporarily installed at the Dublin San Ramon Services District (DSRSD) Wastewater Treatment Plant in Dublin, California. Detailed bioassay testing was conducted on the pilot reactor between October and December 2007. Tests on benchtop reactors were performed in June and August 2007. Pilot tests on the HiPOx reactor located at DSRSD showed that 6.5 log removal of MS2 coliphage was observed at conservative transferred ozone doses of 5 mg/L (contact time of 93 seconds) in microfiltered water, and 7 mg/L (contact time of 50 seconds) in media filtered water. In media filtered water, minimum CT values of 1.0 mg-min/L resulted in non detect total coliform., (IWA Publishing 2008.)

Endocrine-disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) have been detected at low levels in water resources around the world and one impact of their detection is the continuous concern on their fate and removal by various water treatment processes. In this research, a 3D quantitative structure-property relationship (QSPR) model characterized by the utilization of 3D molecular structures is explored as a potential tool to prescreen these compounds and help focus research on more persistent compounds during typical water treatment processes. Monte Carlo (MC) statistical mechanics simulations were utilized to generate 3D molecular descriptors and physicochemical properties for the development of multiple linear regression analysis. The relevance of each parameter to removals of target compounds by ozone (O3) and free chlorine was determined based on data matrices generated in bench- and pilot-scale experiments. Calculated removals were correlated with experimental data with linear regression coefficients of 0.84 for ozonation and 0.71 for chlorination. The increased predictability of ozone removal reflects the fundamental simplicity of ozone reaction mechanisms, which is dominated by oxidation reactions. Interestingly, the weakly polar surface area, in addition to the pi surface area of these molecules, seems critical to ozone removal. The removal of these compounds by free chlorine is related to their ozone removal, ionization potential and three other parameters. The developed QSPR models help disclose the removal mechanism during ozonation and chlorination.

Disinfection byproduct (DBP) formation in tertiary wastewater was examined after ozonation (O(3)) and advanced oxidation with O(3) and hydrogen peroxide (O(3)/H(2)O(2)). O(3) and O(3)/H(2)O(2) were applied at multiple dosages to investigate DBP formation during coliform disinfection and trace contaminant oxidation. Results showed O(3) provided superior disinfection of fecal and total coliforms compared to O(3)/H(2)O(2). Color, UV absorbance, and SUVA were reduced by O(3) and O(3)/H(2)O(2), offering wastewater utilities a few potential surrogates to monitor disinfection or trace contaminant oxidation. At equivalent O(3) dosages, O(3)/H(2)O(2) produced greater concentrations of assimilable organic carbon (5-52%), aldehydes (31-47%), and carboxylic acids (12-43%) compared to O(3) alone, indicating that organic DBP formation is largely dependent upon hydroxyl radical exposure. Bromate formation occurred when O(3) dosages exceeded the O(3) demand of the wastewater. Bench-scale tests with free chlorine showed O(3) is capable of reducing total organic halide (TOX) formation potential by at least 20%. In summary, O(3) provided superior disinfection compared to O(3)/H(2)O(2) while minimizing DBP concentrations. These are important considerations for water reuse, aquifer storage and recovery, and advanced wastewater treatment applications.

The additional removal of trace organic contaminants (TOrCs) provided by advanced water and wastewater treatment inevitably requires additional financial costs, which must be estimated to support utility planning and compare alternatives. This study presents conceptual-level (Class 4) capital and annual operations and maintenance (O&M) cost curve equations to aid evaluations of advanced treatment trains for water reuse. The cost curve equations are broadly applicable to the water reuse community, particularly those interested in ozone-based treatment trains. Unit processes include microfiltration or ultrafiltration membranes (MF/UF), nanofiltration or reverse osmosis membranes (NF/RO), ozone (with or without hydrogen peroxide, H2O2), ultraviolet (UV) treatment with H2O2(UV/H2O2), and biological activated carbon (BAC); all cost curves are for a unit process and can be added together to obtain costs for a combined treatment train. The cost curves indicate that at all plant capacities (1 to 500 MGD), membrane treatment (e.g., MF or RO) represents the highest cost unit process, ozone the least, and BAC or UV/H2O2fall in between. Additionally, the relationship between ozone dose and TOrC removal is discussed with a demonstration of how costs change with increasing ozone dose to achieve desired TOrC destruction. [ABSTRACT FROM AUTHOR]

Increased public awareness, potential human health effects, and demonstrated impacts on aquatic ecosystems have stimulated recent interest in pharmaceuticals, personal care products (PPCPs), and endocrine-disrupting compounds (EDCs) in water and wastewater. Due to the potential public and environmental health implications, some agencies are taking a proactive approach to controlling trace organic contaminant (TOrC) concentrations in water supplies. This review describes some of the research related to the toxicity and estrogenicity of wastewater-derived TOrCs in addition to regulatory guidance from several international agencies. This review also evaluates pilot- and full-scale studies to characterize the efficacy of ozonation for TOrC mitigation in wastewater applications. [ABSTRACT FROM AUTHOR]

This study demonstrated statistical profiling consisting of the analysis of variance (ANOVA) and fold change to efficiently identify transformation products of an organic model compound (i.e., carbamazepine, CBZ) in ozonation. To this end, liquid chromatography (LC)-quadrupole time-of-flight mass spectrometry (QTOF-MS) was employed to measure the accurate masses of CBZ transformation products. Subsequently, statistical profiling was applied to differentiating features that are uniquely present in the ozonated samples from those in blanks and control (i.e., CBZ sample without ozonation). The identified transformation products had significant statistical power (i.e., power, 1- β > 0.8) in post hoc power analysis, which suggests that the profiling procedure can be an efficient means of reducing false negative in data analysis. 2-quinazolinone was newly reported here as a tentative transformation of CBZ during ozonation. In addition, a transformation product with one less carbon than CBZ, often called "anomalous" transformation product, was also found. While statistical profiling was applied to a model experiment, such an approach can be further utilized to screen many features with a higher data complexity such as non-targeted screening (NTS) and non-target analysis (NTA) for environmental samples. Image 1 • Statistical profiling to screen features for mass spectrometry data. • Carbamazepine (CBZ) was ozonated as a model experiment. • Features screened by the ANOVA and fold change showed high statistical power. • Ozonation of carbamazepine tentatively produced 2-quinazolinone. • An anomalous transformation product was produced during the ozonation of CBZ. [ABSTRACT FROM AUTHOR]

This study demonstrated the use of nanofiltration (NF) membrane with pre-ozonation for surface water brine treatment. Pre-ozonation, used for fouling control, with relatively low ozone doses (0.1−0.4 mg O 3 /mg DOC ratios) significantly reduced organic fouling potential. A classical pore blocking model revealed that the dominant fouling mechanism was cake filtration. Based on a statistical correlation test, macromolecules (apparent molecular weight >10 k Da) of typtophan-like aromatic protein and soluble microbial-like matter exhibited strong correlation to fouling potential. Small molecules (<1600 Da) of UV-absorbing matter were also correlated with fouling potential whereas bulk parameters such as SUVA displayed relatively lower correlation with fouling potential. Trace organic compound (TOrC) attenuation by ozone, membranes, and combination of ozone and membranes were also examined. Greater than 70% removal of the 17 TOrCs was achieved at 0.4 mg O 3 /mg DOC ratio. The NF membrane (NF90) alone also could remove more than 90% of TOrCs. When pre-ozonation was performed with the NF membrane, all TOrCs tested were removed to less than the limits of detection. In conclusion, the application of pre-ozonation to NF membrane not only can alleviate organic fouling potential, but also can function as a dual barrier for ensuring removal of TOrCs for water treatment. [ABSTRACT FROM AUTHOR]

The presence of perfluorocarboxylic acids (PFCAs) in source and finished drinking waters is a concern with studies showing bioaccumulation and adverse toxicological effects in wildlife and potentially humans. Per/Polyfluoroalkyl substances (PFAS) such as fluorotelomer alcohols have been identified as precursors for PFCAs in biological pathways. In this study, we investigated the fate of 6:2 and 8:2 homologues of the fluorotelomer unsaturated carboxylic acids (FTUCAs) during advanced oxidation process (AOPs). Results showed 6:2 FTUCA and 8:2 FTUCA transformed into 6-C PFCA (PFHxA) and 8-C PFCA (PFOA) respectively with very little other PFCA formation for all AOPs. The degradation of 6:2 FTUCA and 8:2 FTUCA was greater in the GW compared to SW for the ozone processes but similar for UV/H 2 O 2 . The formation of n-C PFCA followed O 3 > O 3 /H 2 O 2 at same dose and UV/H 2 O 2 had much lower formation at the doses tested. Non-targeted analysis with the LC–MS-qTOF indicated the production of other PFCAs which contribute to the total mass balance, although no intermediate product was discovered indicating a rapid and direct transformation from the FTUCAs to the PFCAs and/or significant volatilization of intermediates. With the use of AOPs essential to water reuse treatment schemes, this work raises concerns over the risk of potential formation of PFCAs in the treatment and their adverse health effects in finished drinking water. [ABSTRACT FROM AUTHOR]

Full-scale experiments to evaluate N-nitrosodimethylamine (NDMA) formation and attenuation were performed within an advanced indirect potable reuse (IPR) treatment system, which includes, sequentially: chloramination for membrane fouling control, microfiltration (MF), reverse osmosis (RO), ultraviolet irradiation with hydrogen peroxide (UV/H 2 O 2 ), final chloramination, and pH stabilization. Results of the study demonstrate that while RO does effectively remove the vast majority of NDMA precursors, RO permeate can still contain significant concentrations of NDMA precursors resulting in additional NDMA formation during chloramination. Thus, it is possible for this advanced treatment system to produce water with NDMA levels higher than regional requirements for potable applications (10 ng/L). The presence of H 2 O 2 during UV oxidation reduced NDMA photolysis efficiency and increased NDMA formation (∼22 ng/L) during the secondary chloramination and lime stabilization. This is likely due to formation of UV/H 2 O 2 degradation by-products with higher NDMA formation rate than the parent compounds. However, this effect was diminished with higher UV doses. Bench-scale experiments confirmed an enhanced NDMA formation during chloramination after UV/H 2 O 2 treatment of dimethylformamide, a compound detected in RO permeate and used as model precursor in this study. The effect of pre-ozonation for membrane fouling control on NDMA formation was also evaluated at pilot- (ozone-MF-RO) and bench-scale. Relatively large NDMA formation (117–227 ng/L) occurred through ozone application that was dose dependent, whereas chloramination under typical dosages and contact times of IPR systems resulted in only a relatively small increase of NDMA (∼20 ng/L). Thus, this research shows that NDMA formation within a potable water reuse facility can be challenging and must be carefully evaluated and controlled. [ABSTRACT FROM AUTHOR]

Ozonation is effective in improving the quality of municipal wastewater effluents by eliminating organic micropollutants. Nevertheless, ozone process design is still limited by (i) the large number of structurally diverse micropollutants and (ii) the varying quality of wastewater matrices (especially dissolved organic matter). These issues were addressed by grouping 16 micropollutants according to their ozone and hydroxyl radical (•OH) rate constants and normalizing the applied ozone dose to the dissolved organic carbon concentration (i.e., g O3/g DOC). Consistent elimination of micropollutants was observed in 10 secondary municipal wastewater effluents spiked with 16 micropollutants (~2 μg/L) in the absence of ozone demand exerted by nitrite. The elimination of ozone-refractory micropollutants was well predicted by measuring the •OH exposure by the decrease of the probe compound p-chlorobenzoic acid. The average molar •OH yields (moles of •OH produced per mole of ozone consumed) were 21 ± 3% for g O3/g DOC = 1.0, and the average rate constant for the reaction of •OH with effluent organic matter was (2.1 ± 0.6) × 104 (mg C/L)-1 s-1. On the basis of these results, a DOC-normalized ozone dose, together with the rate constants for the reaction of the selected micropollutants with ozone and •OH, and the measurement of the •OH exposure are proposed as key parameters for the prediction of the elimination efficiency of micropollutants during ozonation of municipal wastewater effluents with varying water quality. [ABSTRACT FROM AUTHOR]

Abstract: The performance of ozonation in wastewater depends on water quality and the ability to form hydroxyl radicals (et disinfection or contaminant transformation objectives. Since there are no on-line methods to assess ozone and re in wastewater, many agencies are now embracing indicator frameworks and surrogate monitoring for regulatory compliance. Two of the most promising surrogate parameters for ozone-based treatment of secondary and tertiary wastewater effluents are differential UV254 absorbance (ΔUV254) and total fluorescence (ΔTF). In the current study, empirical correlations for ΔUV254 and ΔTF were developed for the oxidation of 18 trace organic contaminants (TOrCs), including 1,4-dioxane, atenolol, atrazine, bisphenol A, carbamazepine, diclofenac, gemfibrozil, ibuprofen, meprobamate, naproxen, N,N-diethyl-meta-toluamide (DEET), para-chlorobenzoic acid (pCBA), phenytoin, primidone, sulfamethoxazole, triclosan, trimethoprim, and tris-(2-chloroethyl)-phosphate (TCEP) (R 2 = 0.50–0.83) and the inactivation of three microbial surrogates, including Escherichia coli, MS2, and Bacillus subtilis spores (R 2 = 0.46–0.78). Nine wastewaters were tested in laboratory systems, and eight wastewaters were evaluated at pilot- and full-scale. A predictive model for re based on ΔUV254 or ΔTF was also proposed. [Copyright &y& Elsevier]

Abstract: An ozone and ozone/peroxide oxidation process was evaluated at pilot scale for trace organic contaminant (TOrC) mitigation and NDMA formation in both drinking water and water reuse applications. A reverse osmosis (RO) pilot was also evaluated as part of the water reuse treatment train. Ozone/peroxide showed lower electrical energy per order of removal (EEO) values for TOrCs in surface water treatment, but the addition of hydrogen peroxide increased EEO values during wastewater treatment. TOrC oxidation was correlated to changes in UV254 absorbance and fluorescence offering a surrogate model for predicting contaminant removal. A decrease in N-nitrosodimethylamine (NDMA) formation potential (after chloramination) was observed after treatment with ozone and ozone/peroxide. However, during spiking experiments with surface water, ozone/peroxide achieved limited destruction of NDMA, while in wastewaters net direct formation of NDMA of 6–33 ng/L was observed after either ozone or ozone/peroxide treatment. Once formed during ozonation, NDMA passed through the subsequent RO membranes, which highlights the significance of the potential for direct NDMA formation during oxidation in reuse applications. [Copyright &y& Elsevier]