Chlorination of Emerging Contaminants for Application in Potable Wastewater Reuse: Disinfection Byproduct Formation, Estrogen Activity, and Cytotoxicity.

With increasing water scarcity, many utilities are considering the potable reuse of wastewater as a source of drinking water. However, not all chemicals are removed in conventional wastewater treatment, and disinfection byproducts (DBPs) can form from these contaminants when disinfectants are applied during or after reuse treatment, especially if applied upstream of advanced treatment processes to control biofouling. We investigated the chlorination of seven priority emerging contaminants (17ß-estradiol, estrone, 17α-ethinylestradiol, bisphenol A (BPA), diclofenac, p-nonylphenol, and triclosan) in ultrapure water, and we also investigated the impact of chlorination on real samples from different treatment stages of an advanced reuse plant to evaluate the role of chlorination on the associated cytotoxicity and estrogenicity. Many DBPs were tentatively identified via liquid chromatography (LC)- and gas chromatography (GC)-high resolution mass spectrometry, including 28 not previously reported. These encompassed chlorinated, brominated, and oxidized analogs of the parent compounds as well as smaller halogenated molecules. Chlorinated BPA was the least cytotoxic of the DBPs formed but was highly estrogenic, whereas chlorinated hormones were highly cytotoxic. Estrogenicity decreased by ∼4-6 orders of magnitude for 17ß-estradiol and estrone following chlorination but increased 2 orders of magnitude for diclofenac. Estrogenicity of chlorinated BPA and p-nonylphenol were ∼50% of the natural/synthetic hormones. Potential seasonal differences in estrogen activity of unreacted vs reacted advanced wastewater treatment field samples were observed.

Degradation of contaminants of emerging concern by UV/H2O2 for water reuse: Kinetics, mechanisms, and cytotoxicity analysis.

Advanced oxidation using UV and hydrogen peroxide (UV/H2O2) has been widely applied to degrade contaminants of emerging concern (CECs) in wastewater for water reuse. This study investigated the degradation kinetics of mixed CECs by UV/H2O2 under variable H2O2 doses, including bisphenol A, estrone, diclofenac, ibuprofen, and triclosan. Reverse osmosis (RO) treated water samples from Orange County Water District's Groundwater Replenishment System (GWRS) potable reuse project were collected on different dates and utilized as reaction matrices with spiked additions of chemicals (CECs and H2O2) to assess the application of UV/H2O2. Possible degradation pathways of selected CECs were proposed based on high resolution mass spectrometry identification of transformation products (TPs). Toxicity assessments included cytotoxicity, aryl hydrocarbon receptor-binding activity, and estrogen receptor-binding activity, in order to evaluate potential environmental impacts resulting from CEC degradation by UV/H2O2. Cytotoxicity and estrogenic activity were significantly reduced during the degradation of mixed CECs in Milli-Q water by UV/H2O2 with high UV fluence (3200 mJ cm-2). However, in GWRS RO-treated water samples collected in April 2017, the cytotoxicity and estrogen activity of spiked CEC-mixture after UV/H2O2 treatment were not significantly eliminated; this might be due to the high concentration of target CEC and their TPs, which was possibly affected by the varied quality of the secondary treatment influent at this facility such as sewer-shed and wastewater discharges. This study aimed to provide insight on the impacts of post-UV/H2O2 CECs and TPs on human and ecological health at cellular level.

Ultrafast photodegradation of isoxazole and isothiazolinones by UV254 and UV254/H2O2 photolysis in a microcapillary reactor.

The photodegradation process of methylisothiazolinone (MIT), benzisothiazolinone (BIT), and isoxazole (ISOX) in ultrapure water and synthetic wastewater by means of UV254 photolysis and by UV254/H2O2 advanced oxidation process were investigated in a microcapillary photoreactor designed for ultrafast photochemical transformation of microcontaminants. For the first time, we estimated key photo-kinetic parameters, i.e. quantum yields (35.4 mmol·ein-1 for MIT, and 13.5 and 55.8 mmol·ein-1 for BIT at pH = 4-6 and 8, respectively) and rate constants of the reaction of photo-generated OH radicals with MIT and BIT (2.09·109 and 5.9·109 L mol-1·s-1 for MIT and BIT). The rate constants of the reaction of photo-generated OH radicals with ISOX in MilliQ water was also estimated (2.15·109 L mol-1·s-1) and it was in good agreement with literature indications obtained in different aqueous matrices. The models were extended and validated to the case of simultaneous degradation of mixtures of these compounds and using synthetic wastewater as an aqueous matrix. High resolution-accurate mass spectrometry analysis enabled identification of the main intermediates (BIT200, B200, saccharin, BIT166) and enabled proposal of a novel degradation pathway for BIT under UV254/H2O2 treatment. This study demonstrates an ultrafast method to determine key photo-kinetic parameters of contaminants of emerging concern in water and wastewater, which are needed for design and validation of photochemical water treatment processes of municipal and industrial wastewaters.

Effects of HCO3- on Degradation of Toxic Contaminants of Emerging Concern by UV/NO3.

This study investigated the significant influence of HCO3- on the degradation of contaminants of emerging concern (CECs) during nitrate photolysis at 254 nm for water reuse applications. The second-order rate constants for the reactions between selected contaminants with carbonate radical (CO3•-) were determined at pH 8.8 and T = 20 °C: estrone ((5.3 ± 1.1) × 108 M-1 s-1), bisphenol A ((2.8 ± 0.2) × 108 M-1 s-1), 17α-ethynylestradiol ((1.6 ± 0.3) × 108 M-1 s-1), triclosan ((4.2 ± 1.4) × 107 M-1 s-1), diclofenac ((2.7 ± 0.7) × 107 M-1 s-1), atrazine ((5.7 ± 0.1) × 106 M-1 s-1), carbamazepine ((4.2 ± 0.01) × 106 M-1 s-1), and ibuprofen ((1.2 ± 1.1) × 106 M-1 s-1). Contributions from UV, reactive nitrogen species (RNS), hydroxyl radical (•OH), and CO3•- to the CEC decomposition in UV/NO3- in the presence and absence of HCO3- were investigated. In addition, possible transformation products and degradation pathways of triclosan, diclofenac, bisphenol A, and estrone in UV/NO3-/HCO3- were proposed based on the mass (MS) and MS2 spectra. Significant reduction in the cytotoxicity of bisphenol A was observed after the treatment with UV/NO3-/HCO3-.

Investigation on the removal of the major cocaine metabolite (benzoylecgonine) in water matrices by UV254/H2O2 process by using a flow microcapillary film array photoreactor as an efficient experimental tool.

A microcapillary film reactor (MCF) was adopted to evaluate and compare the removal efficiency of benzoylecgonine (BE), an emerging micropollutant deriving from illicit drug abuse (cocaine), in different aqueous matrices: milliQ water, synthetic and real wastewater and surface water. The removal processes investigated were the direct photolysis with UV radiation at 254 nm, and the advanced oxidation process (AOP) with the same UV radiation and hydrogen peroxide. As a result of the microfluidics approach developed through an innovative experimental apparatus, full conversion of BE was reached within a few seconds or minutes of residence time in the MCF depending on the process conditions adopted. The radiation dose was estimated to be approximately 5.5 J cm(-2). The innovative MCF reactor was found to be an effective tool for photochemical studies, especially when using highly priced, uncommon, or regulated substances. The removal efficiency was affected by the nature of the aqueous matrix, due to the presence of different xenobiotics and natural compounds that act primarily as HO(•) radical scavengers and secondly as inner UV254 filters. Moreover, nano-liquid chromatography (LC)-high resolution-mass spectrometry analysis was utilized to identify the main reaction transformation products, showing the formation of hydroxylated aromatics during the photochemical treatment.

Analysis of trace fibers by IR-MALDESI imaging coupled with high resolving power MS.

Trace evidence is a significant portion of forensic cases. Textile fibers are a common form of trace evidence that are gaining importance in criminal cases. Currently, qualitative techniques that do not yield structural information are primarily used for fiber analysis, but mass spectrometry is gaining an increasing role in this field. Mass spectrometry yields more quantitative structural information about the dye and polymer that can be used for more conclusive comparisons. Matrix-assisted laser desorption electrospray ionization (MALDESI) is a hybrid ambient ionization source being investigated for use in mass spectrometric fiber analysis. In this manuscript, IR-MALDESI was used as a source for mass spectrometry imaging (MSI) of a dyed nylon fiber cluster and single fiber. Information about the fiber polymer as well as the dye were obtained from a single fiber which was on the order of 10 µm in diameter. These experiments were performed directly from the surface of a tape lift of the fiber with a background of extraneous fibers.

Direct analysis of textile fabrics and dyes using infrared matrix-assisted laser desorption electrospray ionization mass spectrometry.

The forensic analysis of textile fibers uses a variety of techniques from microscopy to spectroscopy. One such technique that is often used to identify the dye(s) within the fiber is mass spectrometry (MS). In the traditional MS method, the dye must be extracted from the fabric and the dye components are separated by chromatography prior to mass spectrometric analysis. Direct analysis of the dye from the fabric allows the omission of the lengthy sample preparation involved in extraction, thereby significantly reducing the overall analysis time. Herein, a direct analysis of dyed textile fabric was performed using the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) source for MS. In MALDESI, an IR laser with wavelength tuned to 2.94 µm is used to desorb the dye from the fabric sample with the aid of water as the matrix. The desorbed dye molecules are then postionized by electrospray ionization (ESI). A variety of dye classes were analyzed from various fabrics with little to no sample preparation allowing for the identification of the dye mass and in some cases the fiber polymer. Those dyes that were not detected using MALDESI were also not observed by direct infusion ESI of the dye standard.