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This paper is a critical review of current knowledge of organic chloramines in water systems, including their formation, stability, toxicity, analytical methods for detection, and their impact on drinking water treatment and quality. The term organic chloramines may refer to any halogenated organic compounds measured as part of combined chlorine (the difference between the measured free and total chlorine concentrations), and may include N -chloramines, N -chloramino acids, N -chloraldimines and N -chloramides. Organic chloramines can form when dissolved organic nitrogen or dissolved organic carbon react with either free chlorine or inorganic chloramines. They are potentially harmful to humans and may exist as an intermediate for other disinfection by-products. However, little information is available on the formation or occurrence of organic chloramines in water due to a number of challenges. One of the biggest challenges for the identification and quantification of organic chloramines in water systems is the lack of appropriate analytical methods. In addition, many of the organic chloramines that form during disinfection are unstable, which results in difficulties in sampling and detection. To date research has focussed on the study of organic monochloramines. However, given that breakpoint chlorination is commonly undertaken in water treatment systems, the formation of organic dichloramines should also be considered. Organic chloramines can be formed from many different precursors and pathways. Therefore, studying the occurrence of their precursors in water systems would enable better prediction and management of their formation. [ABSTRACT FROM AUTHOR]

Cannabinoids are a group of organic compounds found in cannabis. Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two major constituents of cannabinoids, and their metabolites are contaminants of emerging concern due to the limited information on their environmental impacts. As well, their releases to the water systems and environment are expected to increase due to recent legalization. Solid-phase extraction is the most common technique for the extraction and pre-concentration of cannabinoids in water samples as well as a clean-up step after the extraction of cannabinoids from solid samples. Liquid chromatography coupled with mass spectrometry is the most common technique used for the analysis of cannabinoids. THC and its metabolites have been detected in wastewater, surface water, and drinking water. In particular, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) has been detected at concentrations up to 2590 and 169 ng L−1 in untreated and treated wastewater, respectively, 79.9 ng L−1 in surface water, and 1 ng L−1 in drinking water. High removal of cannabinoids has been observed in wastewater treatment plants; this is likely a result of adsorption due to the low aqueous solubility of cannabinoids. Based on the estrogenicity and cytotoxicity studies and modelling, it has been predicted that THC and THC-COOH pose moderate risk for adverse impact on the environment. While chlorination and photo-oxidation have been shown to be effective in the removal of THC-COOH, they also produce by-products that are potentially more toxic than regulated disinfection by-products. The potential of indirect exposure to cannabinoids and their metabolites through recreational water is of great interest. As cannabinoids and especially their by-products may have adverse impacts on the environment and public health, more studies on their occurrence in various types of water and environmental systems, as well as on their environmental toxicity, would be required to accurately assess their impact on the environment and public health. Image 1 • Cannabinoids in wastewater are expected to increase due to legalization. • SPE-LC-MS is most commonly used for cannabinoids analysis. • Adsorption was the main mechanism of removal in wastewater treatment plants. • Transformation products predicted to have negative impact on the environment. • Possible pollutants in recreation waters are expected after legalization. [ABSTRACT FROM AUTHOR]

• Degradation of AO7 by PDS activated from in situ electrochemically generated Cu+. • EC-Cu-PDS have higher degradation efficiency of 70% as compare to 56% of EC-Fe-PDS. • EE/O of the EC-Cu-PDS processes ranged from 0.008 to 2.42 kW h m−3. • Optimal operation condition was pH 2 with cathode to anode area of 4:1. • SO 4 − generated by both electrochemically at the anode and Cu+ activation of PDS. In this paper, the degradation of Acid Orange 7 (AO7), by persulfate activated from in situ electrochemically generated Cu+ (EC-Cu-PDS) was studied. The influence of key parameters such as pH, current density, copper concentration and electrode size were investigated, with the optimal operation condition being pH 2 with cathode to anode area of 4:1. The degradation efficiency of the EC-Cu-PDS after 30 min was compared to the efficiency of other electrocatalysis system using iron, cobalt or silver. The proposed EC-Cu-PDS process has a higher degradation efficiency of 70%, as compare to 56% of the EC-Fe-PDS process. Although the EC-Cu-PDS process has a lower degradation efficiency compared to 100% of Co-PMS and 80% of the EC-Ag-PDS processes, the EC-Cu-PDS process would be cheaper and safer to operate than the latter processes. The estimated electrical energy consumption of the EC-Cu-PDS processes was significantly lower than other electrocatalysis processes, ranging from 0.008 to 2.42 kW h m−3. The degradation of AO7 by the EC-Cu-PDS process was via oxidization of AO7 by both hydroxyl radicals generated at the anode and sulfate radicals generated by both electrochemically at the anode and Cu+ activation of PDS. [ABSTRACT FROM AUTHOR]

In this study, we provide evidence that oil sands process-affected waters (OSPW) contain factors that activate the antimicrobial and proinflammatory responses of immune cells. Specifically, using the murine macrophage RAW 264.7 cell line, we establish the bioactivity of two different OSPW samples and their isolated fractions. Here, we directly compared the bioactivity of two pilot scale demonstration pit lake (DPL) water samples, which included expressed water from treated tailings (termed the before water capping sample; BWC) as well as an after water capping (AWC) sample consisting of a mixture of expressed water, precipitation, upland runoff, coagulated OSPW and added freshwater. Significant inflammatory (i.e. macrophage activating) bioactivity was associated with the AWC sample and its organic fraction (OF), whereas the BWC sample had reduced bioactivity that was primarily associated with its inorganic fraction (IF). Overall, these results indicate that at non-toxic exposure doses, the RAW 264.7 cell line serves as an acute, sensitive and reliable biosensor for the screening of inflammatory constituents within and among discrete OSPW samples. [Display omitted] [ABSTRACT FROM AUTHOR]

This work describes a novel application of atmospheric pressure gas chromatography time-of-flight mass spectrometry (APGC-TOF-MS) combined with solid-phase microextraction (SPME) for the simultaneous analysis of hydrocarbons and naphthenic acids (NAs) species in raw and ozone-treated oil sands process water (OSPW). SPME method using polydimethylsiloxane (PDMS)-coated fibers was validated using gas chromatography with flame ionization detector (GC-FID) to ensure the SPME extractions were operated appropriately. The ionization pathways of the hydrocarbon species in OSPW in the APGC source were verified by analyzing a mixture of eight polyaromatic hydrocarbons which were ionized primarily via charge transfer to produce [M+] while NAs in OSPW were found to be ionized through protonation to generate [MH+] in the wet APGC source. SPME/APGC-TOF-MS analysis demonstrated a different composition profile in OSPW #1, with 74.5% of hydrocarbon species, 23.4% of O 2 –NAs, and 2.1% of the oxidized NA species at extraction pH 2.0 compared with that obtained by UPLC-TOF-MS analysis (36.9% of O 2 –NAs, 26.8% of O 3 –NAs, 24.9% of O 4 –NAs, 9.1% of O 5 –NAs, 2.3% of O 6 –NAs). Moreover, the peak areas of the total NAs and the total peak areas of NAs + hydrocarbons measured by SPME/APGC-TOF-MS correlated excellently with the total NA concentration determined by UPLC-TOF-MS (R2 = 0.90) and the concentrations of the total acid-extractable organics determined by SPME/GC-FID (R2 = 0.98), respectively. APGC-TOF-MS integrated with the SPME techniques could extend the range of target compounds and be a promising alternative to evaluate and characterize NAs and hydrocarbon in different water types. Image 1 • SPME coupled with APGC-TOF-MS was used for analysis of hydrocarbons and NAs. • PDMS fibers preferably extracted neutral organic compounds at natural pH. • The PDMS fibers extracted hydrocarbons and some protonated NAs species at pH 2.0 • PAHs were ionized via charge transfer while NAs were ionized through protonation. • O x -NAs peak areas by SPME/APGC-TOF-MS correlated to the O x -NAs by UPLC-TOF-MS. [ABSTRACT FROM AUTHOR]

• CHA degradation was mainly attributed to OH radical attack. • Dividing the chlorine dose into five separated doses increased the removal rate. • Different by-products were identified including two chlorine-containing by-products. • The reaction pathway for CHA degradation during UV/Chlorine treatment was proposed. Degradation kinetics, by-products identification and pathways of a model naphthenic acid, cyclohexanecarboxylic acid (CHA), by the UV/Chlorine process were investigated in this study. Mathematical modeling indicated that the initial CHA decay rate increased rapidly with the chlorine dose when the chlorine dose was lower than 45 mg/L and decreased with further chlorine dose increases. Increasing the chlorine dose from 400 to 800 mg/L resulted in a steady increase in the total removal of CHA after 60 min of UV photolysis. By dividing the 700 mg/L chlorine dose into five separated doses (140 mg/L each) added at 10 min intervals, the total CHA removal increased from 72% to 91%. This implies that the ideal condition of the UV/Chlorine process in degrading CHA is to add chlorine continuously at a constant rate to compensate any chlorine consumption to reduce the radical scavenging effect. It was found that the CHA decay was mainly attributed to the hydroxyl radical (OH) attack and the reactive chlorine species (RCS) contribution was relatively small. Various by-products, including the mono-chlorinated and di-chlorinated by-products, were identified and the reaction pathway for CHA degradation during UV/Chlorine treatment was proposed. [ABSTRACT FROM AUTHOR]

This paper reported the impact of UV/H 2 O 2 , UV/chlorine, and UV/persulfate advanced oxidation processes on the molecular transformations of dissolved organic matter (DOM), removal of naphthenic acids (NAs) and acute toxicity in oil sands process water (OSPW). The UV/persulfate process exhibited the highest removal (81.2% with 2 mM dose) towards classical NAs and highest reduction in acute toxicity to Vibrio fischeri among the three processes. The fraction of DOM such as CHOS class species decreased along with the increase of the oxidant doses in all processes. The increase in O/C ratio and lack of change in the H/C and double bond equivalence indicated that H-abstraction followed by the OH-addition was the main reaction pathway for all processes. This observation aligned with previous studies using model compounds and proved that OSPW DOM reacted similarly to model compounds. Sulfur containing organic matters were the most liable compounds in OSPW NOM, while UV/chlorine was the most effective process to oxidize nitrogen containing organic matters. Overall results revealed that the UV/persulfate process could be used as a promising technique for the removal of OSPW NA and reduction of acute toxicity towards Vibrio fischeri. In addition, this DOM characterization approach could be utilized to investigate the transformation of complicated OSPW DOM and to identify the byproducts generated during different water treatment processes. Unlabelled Image • UV/persulfate had the highest O 2 -NA removal. • UV/persulfate had the highest reduction in acute toxicity to Vibrio fischeri. • H-abstraction followed by OH-addition was the main reaction pathway for all processes. • Sulfur containing organic matters were the most liable compounds in OSPW NOM. • Chlorinated byproducts were formed in both UV/chlorine and UV/persulfate. [ABSTRACT FROM AUTHOR]

Oil sands process water (OSPW) contains complex components of inorganics and organics. This is the first study that separated OSPW inorganic and organic fractions and examined their relative acute toxicity when compared with the original whole OSPW using an in-vitro cell-based bio-indicator system. The separation of OSPW inorganic and organic fractions would be conducive to the understanding of the toxic contribution of organic and inorganic fractions as well as the identification and treatment of organic fractions. In this research, we demonstrated that the highest organic fraction extraction was obtained using HLB solid phase extraction with 95.4 ± 0.7% of dissolved organic carbon (DOC) and 90.0 ± 5.3% of naphthenic acid (NA) recovered from OSPW, which were higher than those obtained using the traditional dichloromethane liquid-liquid extraction (48.8 ± 0.2% of DOC and 81.0 ± 2.6% of NA recovery) or other SPE cartridges tested. We also reported the first isolation method for OSPW inorganic fraction by removing 96.1 ± 0.2% of DOC in OSPW using granular activated carbon. The difference of other parameters such as pH, alkalinity, conductivity, and concentration of detected ions between OSPW and isolated inorganic fraction was negligible. The acute toxicity of whole OSPW, separated OSPW inorganic fraction and organic fraction, and the reconstituted fractions were assessed using in-vitro bioassays with RAW 264.7 mouse macrophage cell lines. OSPW organic fraction demonstrated significant cytotoxicity at 14 mg/L O 2 -NA and affected the cellular metabolic activity at 10 mg/L of O 2 -NAs. No significant cytotoxicity or effect on cellular metabolic activity was observed for whole OSPW, OSPW inorganic fraction and the reconstituted fractions. Overall, this study provides the procedure for the isolation of the major components of OSPW (i.e., organics and inorganics), which allows the assessment of their relative toxicological effects using a standard in-vitro bioassay and would allow more accurate characterization and treatment study for each fraction in OSPW. Unlabelled Image • HLB cartridge effectively recovered DOC and NAs from oil sands process water (OSPW). • HLB cartridge was able to extract O 2 – to O 5 –NAs. • GAC effectively removed the organics in OSPW and isolated the OSPW inorganics. • Isolated OSPW organics showed enhanced cytotoxicity compared to whole OSPW. [ABSTRACT FROM AUTHOR]

Highly polluted crude oil electric desalting wastewaters (EDWs) severely affect the efficiency of refinery wastewater treatment plants (WWTPs). Coagulation is an efficient pretreatment to reduce the impacts of EDWs. In the present study, the influences of coagulation pretreatment on the characteristics of EDWs of three typical Chinese crude oils, Liaohe heavy oil (LHO), Karamay heavy oil (KHO) and Daqing light oil (DLO), were investigated. The stability of three raw EDWs was broken and the contents of organic pollutants were significantly reduced by aluminum sulfate coagulation. More soluble COD and polar oils were removed from LHO-EDW (1241 and 98 mg L−1) and KHO-EDW (779 and 57 mg L−1) compared to DLO-EDW (417 and 11 mg L−1). Coagulation significantly changed the compositions of the organic pollutants of two heavy oil EDWs; however, slightly influenced DLO-EDW, particularly the polar organic pollutants. Most types of aromatic compounds, aliphatic acids and O x polar compounds were removed from two heavy oil EDWs, but mainly alkanes were removed from DLO-EDW. As such, the differences in the types of dominant polar compounds became insignificant among treated heavy oil and light oil EDWs. Coagulation notably decreased the acute biotoxicity and improved the biodegradability of all treated EDWs. The residual organic nitrogen compounds in treated KHO-EDW contributed to a higher residual biotoxicity compared to treated LHO-EDW. The results demonstrate that coagulation can effectively improve the qualities of heavy oil EDWs by lowering the contents of organic pollutants and removing recalcitrant compounds, thus guaranteeing the efficiency of refinery WWTPs. Image 1 • Coagulation is effective in breaking the stability and reducing pollutants contents. • Coagulation decreased the acute biotoxicity and improved the biodegradability of all EDWs. • Mainly polar compounds were removed from two heavy oil EDWs. • Mainly alkanes were removed from DLO-EDW. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) filters are compounds utilized in many manufacturing processes and personal care products such as sunscreen to protect against UV-radiation. These highly lipophilic compounds are emerging contaminants of concern in aquatic environments due to their previously observed potential to bioaccumulate and exert toxic effects in marine ecosystems. Currently, research into the toxic effects of UV filter contamination of freshwater ecosystems is lacking, thus the present study sought to model the effects of acute and chronic developmental exposures to UV filters avobenzone, oxybenzone and octocrylene as well as a mixture of these substances in the freshwater invertebrate, Daphnia magna , at environmentally realistic concentrations. Median 48-hour effect and lethal concentrations were determined to be in the low mg/L range, with the exception of octocrylene causing 50% immobilization near environmental concentrations. 48-hour acute developmental exposures proved to behaviourally impair daphnid phototactic response; however, recovery was observed following a 19-day post-exposure period. Although no physiological disruptions were detected in acutely exposed daphnids, delayed mortality was observed up to seven days post-exposure at 200 μg/L of avobenzone and octocrylene. 21-day chronic exposure to 7.5 μg/L octocrylene yielded complete mortality within 7 days, while sublethal chronic exposure to avobenzone increased Daphnia reproductive output and decreased metabolic rate. 2 μg/L oxybenzone induced a 25% increase in metabolic rate of adult daphnids, and otherwise caused no toxic effects at this dose. These data indicate that UV filters can exert toxic effects in freshwater invertebrates, therefore further study is required. It is clear that the most well-studied UV filter, oxybenzone, may not be the most toxic to Daphnia , as both avobenzone and octocrylene induced behavioural and physiological disruption at environmentally realistic concentrations. Unlabelled Image • D. magna neonates were exposed to ultraviolet filters (UVFs) for 2 or 21 days. • 48-hour UVF exposure reduced survivorship and behaviourally impaired daphnids. • Chronic exposure to 7.5 μg/L octocrylene resulted in complete 7-day mortality. • Chronic exposure to avobenzone or oxybenzone disrupted daphnid metabolic rate. • UVFs exhibit toxicity to Daphnia at environmentally realistic concentrations. [ABSTRACT FROM AUTHOR]

Naphthenic acid fraction compounds (NAFCs), defined herein as the polar organic compounds extracted from the acidified oil sands process water (OSPW) samples using dichloromethane, are becoming the research hotspot due to their presence in large amount in OSPW and along with other potentially NA-contaminated water streams from the mining site. Fourier transform infrared spectroscopy (FTIR) method is commonly used to quantify NAFCs and assumes that the total NA concentration is measured as the sum of the responses for all carboxylic acid functional groups. In this study, the NAFCs in various OSPW and groundwater (GW) samples from an active oil sands mining site were analyzed using FTIR. All water samples were pretreated using either solid-phase extraction (SPE) or liquid-liquid extraction (LLE) methods before analysis. The results showed that SPE produced higher recoveries of NAFCs than LLE for most water samples under current experimental conditions. For the quantification of NAFCs, commercial Fluka NA mixture and a pre-calibrated OSPW extract were employed as the calibration standards. The NAFCs calibrated with Fluka NA mixture and OSPW extract had clear linear relationships. The concentrations of NAFCs obtained using OSPW extract standard curve were 2.5 times the NAFC concentrations obtained using the Fluka NA mixture standard curve. Additionally, good linear correlations were observed between the total NAs and O 2 -O 6 NA species determined by ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-TOFMS) and the NAFCs measured by FTIR. According to these correlations, the NA compositions in NAFCs were developed, and the relative abundances of O 2 -O 6 NA species in NAFCs were similar for SPE and LLE pretreated samples. The findings of this study demonstrated that FTIR could be used as a promising tool to monitor total NA species and to estimate the NA profile in different environmental water samples. Unlabelled Image • We compared FTIR and UPLC-TOFMS with different extraction methods (LLE and SPE). • SPE produced higher recoveries of NAFCs than LLE for most water samples. • Higher NAFC concentrations were produced with OSPW extract than those with Fluka. • Good linear correlations were observed between UPLC-TOFMS and FTIR. • FTIR provided fast and accurate estimation of the NA species composition. [ABSTRACT FROM AUTHOR]

Large quantities of highly polluted point-source wastewaters (EDWs) are generated from electric desalting process of heavy oils (HOs), resulting in severe impacts on the efficiency of wastewater treatment plants in petroleum refineries. In the present study, a comprehensive chemical analysis and characterization of EDWs of two typical Chinese heavy oils, Liaohe heavy oil (LHO) and Karamy heavy oil (KHO), were investigated using Daqing light oil (DLO) as a control. The HO-EDWs (LHO-EDW and KHO-EDW) show high pollutants contents with complicated compositions, more polar dissolved organic pollutants (DOPs), strong emulsion stability and high acute biotoxicity towards Vibrio fischeri , compared to DLO-EDW. LHO-EDW and KHO-EDW have nearly equal pollutants contents but different compositions and distributions, where more types of DOPs exist in KHO-EDW. Large amounts of biologically recalcitrant aromatic compounds, as well as heteroatomic compounds such as CHO, CHOS and CHON species, extensively distribute in HO-EDWs. The organic nitrogen compounds (e.g., anilines and N 2 – 3 O x , N 1 O x S 1) in KHO-EDW most probably contribute to and thus leading to elevated levels of acute biotoxicity. Additionally, highly dispersed colloidal, micron-sized particles and polar compounds promote the emulsification and stabilization of HO-EDWs. These results can guide the development of pretreatment technologies for HO-EDWs, thus improving the treatment and management of heavy oil refineries' wastewater streams. Unlabelled Image • The characteristics of HO-EDWs in refineries were comprehensively investigated. • EDWs were characterized by a combination of 3D-EEM, GC–MS and FT-ICR MS. • Polar oils and DOPs resulted in high pollutants contents, stability and biotoxicity. • Pretreatments for reducing the impacts of HO-EDWs on WWTP were proposed. [ABSTRACT FROM AUTHOR]

Chlorination of amino acids can result in the formation of organic monochloramines or organic dichloramines, depending on the chlorine to amino acid ratio (Cl:AA). After formation, organic chloramines degrade into aldehydes, nitriles and N-chloraldimines. In this paper, the formation of organic chloramines from chlorination of lysine, tyrosine and valine were investigated. Chlorination of tyrosine and lysine demonstrated that the presence of a reactive secondary group can increase the Cl:AA ratio required for the formation of N,N-dichloramines, and potentially alter the reaction pathways between chlorine and amino acids, resulting in the formation of unexpected byproducts. In a detailed investigation, we report rate constants for all reactions in the chlorination of valine, for the first time, using experimental results and modeling. At Cl:AA = 2.8, the chlorine was found to first react quickly with valine (5.4 × 10 4 M -1 s -1 ) to form N-monochlorovaline, with a slower subsequent reaction with N-monochlorovaline to form N,N-dichlorovaline (4.9 × 10 2 M -1 s -1 ), although some N-monochlorovaline degraded into isobutyraldehyde (1.0 × 10 -4 s -1 ). The N,N-dichlorovaline then competitively degraded into isobutyronitrile (1.3 × 10 -4 s -1 ) and N-chloroisobutyraldimine (1.2 × 10 -4 s -1 ). In conventional drinking water disinfection, N-chloroisobutyraldimine can potentially be formed in concentrations higher than its odor threshold concentration, resulting in aesthetic challenges and an unknown health risk.