Browsing by Author "Verwold, Chad"

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    Emerging disinfection by-product quantification method for wastewater reuse: trace level assessment using tandem mass spectrometry
    (Royal Society of Chemistry, 2021-01-13) Ortega-Hernandez, Alejandro; Acabaya, Raphael; Verwold, Chad; Montagner, Cassiana Carolina; Kimura, Susana Y.
    The availability of freshwater sources are declining as the result of increasing populations, economic activities, and climate change. These increasing trends will also drive up the demand for potable water that will require the use of alternative sources including wastewater-impacted and saline waters. Therefore, it is crucial to understand the formation of emerging toxic DBPs from advanced treatment of treated secondary wastewater effluents for potable reuse. In this study, a highly sensitive analytical method was developed to characterize 25 DBPs from 5 chemical classes (haloacetonitriles, halonitromethanes, haloacetaldehydes, haloketones, and iodinated trihalomethanes) in recycled wastewaters using a gas chromatography tandem mass spectrometer (MS/MS). The high sensitivity of MS/MS technology permitted a reduced sample concentration factor (50x) that required only 30 min of extraction time and 10 mL of sample volume. Method detection limits are the lowest reported between 2.0-68.9 ng/L. Matrix effects in secondary wastewater effluents were low (0-30%) compared to ultra pure water. A full-scale facility for wastewater reuse that treated secondary wastewater effluents through microfiltration (UF), followed by ozone (UF/O3) or reverse osmosis (UF/RO) was evaluated. Water samples from each process were chlorinated (HOCl) and chloraminated (NH2Cl) to evaluate DBP precursor removal and DBP formation potential, the first study of its kind. Overall, HOCl formed higher summed DBP levels (0.5-18.5 ug/L) compared to NH2Cl (0.2-8.5 ug/L). HAN was significantly lower in UF/O3/HOCl (59%) and UF/RO/HOCl (99%) compared to UF/HOCl. However, HNM was enhanced after UF/O3/HOCl. In chloraminated samples, UF/O3/NH2Cl produced a higher amount of DBPs compared to UF/NH2Cl including haloacetonitriles, halonitromethanes, haloketones, and iodinated trihalomethanes.
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    New Iodine-based Electrochemical Advanced Oxidation System for Water Disinfection: Are Disinfection By-products a Concern?
    (Elsevier; IWA Publishing, 2021-06-23) Verwold, Chad; Ortega-Hernandez, Alejandro; Murakami, Jillian; Patterson-Fortin, Laura; Boutros, Jenny; Smith, Richard; Kimura, Susana Y.
    A novel electrochemical Advanced Oxidation System (AOS) has been recently developed for water disinfection where iodide is used to generate active iodine species in-situ. However, the presence of iodide during water disinfection can lead to the formation of iodinated disinfection byproducts (I-DBPs), which have been shown to be more cyto- and genotoxic than their chlorinated and brominated analogs. In this study, the formation of DBPs was assessed in ultrapure water, river water and secondary wastewater effluents treated by the AOS. A comprehensive total organic halogen and target DBP analysis was used that included 25 unregulated DBPs, and the total organic halogen (TOX) quantified as total organic chlorine (TOCl), total organic bromine (TOBr), and total organic iodine (TOI). Ultrapure water disinfection only quantified iodoform (TIM) at a maximum concentration of 0.90 ± 0.05 µg/L. River water results show that TOI increase from 1.3 ± 0.3 µg/L before disinfection (t=0) to a maximum of 3.5 ±1.1 µg/L. TIM and bromodiiodomethane (BDIM) were the only targeted iodo-trihalomethanes (I-THMs) that were quantified with a maximum total I-THM concentration of 0.44 µg/L. Secondary wastewater effluent disinfection results show that TOI increased from 1.8 ± 0.3 µg/L (t=0) to a maximum concentration of 35.3 ± 0.3 µg/L. Iodide and iodate were the main iodinated species exiting the AOS system with a iodine recovery of 94-101%. The results from this study show that the AOS formed low levels of iodinated DBPs in treated water sources that are comparable to the levels found in disinfected drinking water and wastewater.