Nontargeted Analysis of Trace Organic Constituents in Reverse Osmosis and UV-AOP Product Waters of a Potable Reuse Facility

Abstract

To evaluate the ultraviolet (UV) advanced oxidation process (AOP) in a potable reuse facility, we characterized organic compounds in upstream reverse osmosis (RO)-treated recycled municipal wastewater samples collected before and after UV/H 2 O 2 AOP by implementing nontargeted analysis (NTA) based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Five sampling events were conducted at an advanced water purification facility. Fewer compounds were found consistently in the UV-AOP product water (UVP) than the corresponding feedwater (RO permeate (ROP)): on average, 28 compounds (by quality control criteria) in ROP vs 10 in UVP. On average, 80% of the qualified compounds were tentatively identified by mass spectral comparison with the NIST EI library, followed by a 87.5% verification success rate with standards for 24 selected compounds. Halogenated acetonitriles were most frequently found in UVP. Six compounds found in UVP were also present in tested tap water. Only one of the compounds, bromodichloromethane, has a regulatory limit in drinking water. This exploratory study concluded that, in the context of potable water reuse, NTA was useful for identifying contaminants without a priori knowledge of their occurrence and that the UV/H 2 O 2 AOP effectively removed trace organics that persisted in the ROP.

Comparison of Trace Organic Chemical Removal Efficiencies between Aerobic and Anaerobic Membrane Bioreactors Treating Municipal Wastewater

“…The rate of success for verifying tentatively identified compounds against synthetic standards ranged from 88 to 100% in our previous studies, using a similar GC×GC/TOF-MS method and search against the NIST mass spectral library. ,, In this study, 15 chemicals were selected from the set of compounds commonly identified across three different WWTF influents in Mladenov et al, one of which provided the influent for the current study. One hundred percent of the compounds were verified with their authentic standard, and their treatment by the MBR systems and the full-scale WWTFs from Mladenov et al were compared.…”

Comparison of Oxidants Used in Advanced Oxidation for Potable Reuse: Non-Target Analysis and Bioassays

“…Compounds containing only CHO or CHON were the most abundant of those classified, similar to other studies of organic matter occurring in drinking water and wastewater. 25,58,59 The transformations of organic compounds across ROP to UVP are depicted as van Krevelen diagrams in Figure 3 non-target features where formulae were assigned, UV/HOCl, UV/H 2 O 2 , and UV/ambient had similar removal (30−33%, the gray circle and cross) but UV/NH 2 Cl increased the number of compounds with assigned formulae by 35%. This may be an artifact of the ∼30% of the features that were not assigned a formula in the UV/ambient sample.…”

“…Compounds containing only CHO or CHON were the most abundant of those classified, similar to other studies of organic matter occurring in drinking water and wastewater. 25,58,59 The transformations of organic compounds across ROP to UVP are depicted as van Krevelen diagrams in Figure 3. In terms of the non-target features where formulae were assigned, UV/HOCl, UV/H 2 O 2 , and UV/ambient had similar removal (30−33%, the gray circle and cross) but UV/NH 2 Cl increased the number of compounds with assigned formulae by 35%.…”

“…Non-target analysis (NTA) is a separate method of identifying unknown chemicals by their mass to charge ratio alone without prior information . Some studies have utilized NTA to investigate the occurrence of organic contaminants at potable reuse facilities. ,− However, there are few NTA studies that have sought to investigate the fraction of organic compounds that persist through potable reuse, and thus, the composition of these recalcitrant organic compounds is relatively unknown. In addition to chemical analysis, in vitro bioassays have been proposed to assess water quality .…”

Leached Compounds from Smoked Cigarettes and Their Potential for Bioaccumulation in Rainbow Trout (Oncorhynchus mykiss)

“…To determine the major compounds from smoked cigarette leachate, we used a nontargeted analytical technique based on comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC/TOF-MS). GC×GC/TOF-MS-based nontargeted analysis has been successfully implemented in order to identify known and unknown contaminants in a wide variety of sample matrixes such as human breastmilk, waste and stormwater, and wildlife. − Additionally, nontargeted analysis has been implemented in conjunction with toxicological studies in order to identify potentially toxic compounds . Furthermore, the United States Environmental Protection Agency (EPA) nontargeted analysis collaborative trial (ENTACT) demonstrated the power of GC-based nontargeted analysis, where GC-based methods correctly identified 809 substances and LC-based methods correctly identified 801 (539 by ESI+ and 262 by ESI−) …”