Pilot-scale hybrid constructed wetlands for the treatment of cooling tower water prior to its desalination and reuse.

Cooling towers are responsible for a large part of the industrial fresh water withdrawal, and the reuse of cooling tower water (CTW) effluents can strongly lower industrial fresh water footprints. CTW requires desalination prior to being reused, but various CTW components, such as total organic carbon (TOC), conditioning chemicals and total suspended solids (TSS) hamper physico-chemical desalination technologies and need to be removed from the CTW. A cost-efficient and robust pre-treatment is thus required, which can be provided by constructed wetlands (CWs). The present study is the first study that determined the CTW pre-treatment efficiency of hybrid-CWs and the impact of winter season and biocides in the CTW on the pre-treatment efficiency. The most efficient CW flow type and dominant removal mechanisms for CW components hampering physico-chemical desalination were determined. Subsurface flow CWs removed PO43-, TSS and TOC as a result of adsorption and filtration. Vertical subsurface flow CWs (VSSF-CW) excelled in the removal of benzotriazole as a result of aerobic biodegradation. Horizontal subsurface flow CWs (HSSF-CW) allowed the denitrification of NO3- due to their anaerobic conditions. Open water CWs (OW-CWs) did not contribute to the removal of components that hamper physico-chemical desalination technologies, but do provide water storage options and habitat. The biological removal processes in the different CW flow types were negatively impacted by the winter season, but were not impacted by concentrations of the biocides glutaraldehyde and DBNPA that are relevant in practice. For optimal pre-treatment, a hybrid-CW, consisting of an initial VSSF-CW followed by an OW-CW and HSSF-CW is recommended. Future research should focus on integrating the hybrid-CW with a desalination technology, e.g. reverse osmosis, electrodialysis or capacitive ionization, to produce water that meets the requirements for use as cooling water and allow the reuse of CTW in the cooling tower itself.

Mass spectrometric strategies for the investigation of biomarkers of illicit drug use in wastewater.

The analysis of illicit drugs in urban wastewater is the basis of wastewater-based epidemiology (WBE), and has received much scientific attention because the concentrations measured can be used as a new non-intrusive tool to provide evidence-based and real-time estimates of community-wide drug consumption. Moreover, WBE allows monitoring patterns and spatial and temporal trends of drug use. Although information and expertise from other disciplines is required to refine and effectively apply WBE, analytical chemistry is the fundamental driver in this field. The use of advanced analytical techniques, commonly based on combined chromatography-mass spectrometry, is mandatory because the very low analyte concentration and the complexity of samples (raw wastewater) make quantification and identification/confirmation of illicit drug biomarkers (IDBs) troublesome. We review the most-recent literature available (mostly from the last 5 years) on the determination of IDBs in wastewater with particular emphasis on the different analytical strategies applied. The predominance of liquid chromatography coupled to tandem mass spectrometry to quantify target IDBs and the essence to produce reliable and comparable results is illustrated. Accordingly, the importance to perform inter-laboratory exercises and the need to analyze appropriate quality controls in each sample sequence is highlighted. Other crucial steps in WBE, such as sample collection and sample pre-treatment, are briefly and carefully discussed. The article further focuses on the potential of high-resolution mass spectrometry. Different approaches for target and non-target analysis are discussed, and the interest to perform experiments under laboratory-controlled conditions, as a complementary tool to investigate related compounds (e.g., minor metabolites and/or transformation products in wastewater) is treated. The article ends up with the trends and future perspectives in this field from the authors' point of view. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:258-280, 2018.

Nontarget Screening Reveals Time Trends of Polar Micropollutants in a Riverbank Filtration System.

The historic emissions of polar micropollutants in a natural drinking water source were investigated by nontarget screening with high-resolution mass spectrometry and open cheminformatics tools. The study area consisted of a riverbank filtration transect fed by the river Lek, a branch of the lower Rhine, and exhibiting up to 60-year travel time. More than 18,000 profiles were detected. Hierarchical clustering revealed that 43% of the 15 most populated clusters were characterized by intensity trends with maxima in the 1990s, reflecting intensified human activities, wastewater treatment plant upgrades and regulation in the Rhine riparian countries. Tentative structure annotation was performed using automated in silico fragmentation. Candidate structures retrieved from ChemSpider were scored based on the fit of the in silico fragments to the experimental tandem mass spectra, similarity to openly accessible accurate mass spectra, associated metadata, and presence in a suspect list. Sixty-seven unique structures (72 over both ionization modes) were tentatively identified, 25 of which were confirmed and included contaminants so far unknown to occur in bank filtrate or in natural waters at all, such as tetramethylsulfamide. This study demonstrates that many classes of hydrophilic organics enter riverbank filtration systems, persisting and migrating for decades if biogeochemical conditions are stable.

How to Adapt Chemical Risk Assessment for Unconventional Hydrocarbon Extraction Related to the Water System.

We identify uncertainties and knowledge gaps of chemical risk assessment related to unconventional drillings and propose adaptations. We discuss how chemical risk assessment in the context of unconventional oil and gas (UO&G) activities differs from conventional chemical risk assessment and the implications for existing legislation. A UO&G suspect list of 1,386 chemicals that might be expected in the UO&G water samples was prepared which can be used for LC-HRMS suspect screening. We actualize information on reported concentrations in UO&G-related water. Most information relates to shale gas operations, followed by coal-bed methane, while only little is available for tight gas and conventional gas. The limited research on conventional oil and gas recovery hampers comparison whether risks related to unconventional activities are in fact higher than those related to conventional activities. No study analyzed the whole cycle from fracturing fluid, flowback and produced water, and surface water and groundwater. Generally target screening has been used, probably missing contaminants of concern. Almost half of the organic compounds analyzed in surface water and groundwater exceed TTC values, so further risk assessment is needed, and risks cannot be waived. No specific exposure scenarios toward groundwater aquifers exist for UO&G-related activities. Human errors in various stages of the life cycle of UO&G production play an important role in the exposure. Neither at the international level nor at the US federal and the EU levels, specific regulations for UO&G-related activities are in place to protect environmental and human health. UO&G activities are mostly regulated through general environmental, spatial planning, and mining legislation.

Biodegradation of metformin and its transformation product, guanylurea, by natural and exposed microbial communities.

Metformin (MET) is a pharmaceutical product mostly biotransformed in the environment to a transformation product, guanylurea (GUA). In ready biodegradability tests (RBTs), however, contrasting results have been observed for metformin. The objective of this study was to measure the biodegradation of MET and GUA in RBTs, using activated sludge from the local wastewater treatment plant, either directly or after pre-exposure to MET, in a chemostat. The activated sludge community was cultivated in chemostats, in presence or absence of MET, for a period of nine months, and was used in RBT after one, three and nine months. The results of this study showed that the original activated sludge was able to completely remove MET (15 mg/l) and the newly produced GUA (50% of C0MET) under the test conditions. Inoculation of the chemostat led to a rapid shift in the community composition and abundance. The community exposed to 1.5 mg/l of MET was still able to completely consume MET in the RBTs after one-month exposure, but three- and nine-months exposure resulted in reduced removal of MET in the RBTs. The ability of the activated sludge community to degrade MET and GUA is the result of environmental exposure to these chemicals as well as of conditions that could not be reproduced in the laboratory system. A MET-degrading strain belonging to the genus Aminobacter has been isolated from the chemostat community. This strain was able to completely consume 15 mg/l of MET within three days in the test. However, community analysis revealed that the fluctuation in relative abundance of this genus (<1%) could not be correlated to the fluctuation in biodegradation capacity of the chemostat community.

Wastewater-based tracing of doping use by the general population and amateur athletes.

The present study investigates the applicability of the chemical analysis of wastewater to assess the use of doping substances by the general population and amateur athletes. To this end, an analytical methodology that can identify and quantify a list of 15 substances from the groups of anabolic steroids, weight loss products, and masking agents in wastewater has been developed. The method uses solid phase extraction to increase the detection sensitivity of the target analytes, expected to be present at very low concentrations (ng L-1 range), and decrease possible matrix interferences. Instrumental analysis is performed by liquid chromatography coupled to high-resolution mass spectrometry, allowing data acquisition in both full scan and tandem MS mode. The method has been successfully validated at two concentration levels (50 and 200 ng L-1) with limits of quantification ranging between 0.7 and 60 ng L-1, intra- and inter-day precision expressed as relative standard deviation below 15%, procedural recoveries between 60 and 160% and matrix effects ranging from 45 to 121%. The stability of the analytes in wastewater was evaluated at different storage temperatures illustrating the importance of freezing the samples immediately after collection. The application of the method to 24-h composite wastewater samples collected at the entrance of three wastewater treatment plants and one pumping station while different sport events were taking place revealed the presence in wastewater, and hence the use, of the weight loss substances ephedrine, norephedrine, methylhexanamine, and 2,4-dinitrophenol. The use of these stimulants was visible just prior and during the event days and in greater amounts than anabolic steroids or masking agents. Graphical abstract Chemical analysis of untreated wastewater reveals the use of prohibited doping substances during amateur sport event.

Wastewater Analysis for Community-Wide Drugs Use Assessment.

Wastewater-based epidemiology (WBE) complements existing epidemiology-based estimation techniques and provides objective, evidence-based estimates of illicit drug use. After consumption, biomarkers - drugs and their metabolites - excreted to toilets and flushed into urban sewer networks can be measured in raw wastewater samples. The quantified loads can serve as an estimate for the collective consumption of all people contributing to the wastewater sample. This transdisciplinary approach, further explained in this chapter, has developed, matured and is now established for monitoring substances such as cocaine and amphetamine-type stimulants. Research currently underway is refining WBE to new applications including new psychoactive substances (NPS).

Transformation and Sorption of Illicit Drug Biomarkers in Sewer Biofilms.

In-sewer transformation of drug biomarkers (excreted parent drugs and metabolites) can be influenced by the presence of biomass in suspended form as well as attached to sewer walls (biofilms). Biofilms are likely the most abundant and biologically active biomass fraction in sewers. In this study, 16 drug biomarkers were selected, including the parent forms and the major human metabolites of mephedrone, methadone, cocaine, heroin, codeine, and tetrahydrocannabinol (THC). Transformation and sorption of these substances were assessed in targeted batch experiments using laboratory-scale biofilm reactors operated under aerobic and anaerobic conditions. A one-dimensional model was developed to simulate diffusive transport, abiotic and biotic transformation, and partitioning of drug biomarkers. Model calibration to experimental results allowed estimating biotransformation rate constants in sewer biofilms, which were compared to those obtained for suspended biomass. Our results suggest that sewer biofilms can enhance the biotransformation kinetics of most selected compounds. Through scenario simulations, we demonstrated that the estimation of biotransformation rate constants in biofilm can be significantly biased if the boundary layer thickness is not accurately estimated. This study complements our previous investigation on the transformation and sorption of drug biomarkers in the presence of only suspended biomass in untreated sewage. A better understanding of the role of sewer biofilms-also relative to the in-sewer suspended solids-and improved prediction of associated fate processes can result in more accurate estimation of daily drug consumption in urban areas in wastewater-based epidemiological assessments.

Modelling the Release, Transport and Fate of Engineered Nanoparticles in the Aquatic Environment - A Review.

Engineered nanoparticles, that is, particles of up to 100 nm in at least one dimension, are used in many consumer products. Their release into the environment as a consequence of their production and use has raised concern about the possible consequences. While they are made of ordinary substances, their size gives them properties that are not manifest in larger particles. It is precisely these properties that make them useful. For instance titanium dioxide nanoparticles are used in transparent sunscreens, because they are large enough to scatter ultraviolet light but too small to scatter visible light.To investigate the occurrence of nanoparticles in the environment we require practical methods to detect their presence and to measure the concentrations as well as adequate modelling techniques. Modelling provides both a complement to the available detection and measurement methods and the means to understand and predict the release, transport and fate of nanoparticles. Many different modelling approaches have been developed, but it is not always clear for what questions regarding nanoparticles in the environment these approaches can be applied. No modelling technique can be used for every possible aspect of the release of nanoparticles into the environment. Hence it is important to understand which technique to apply in what situation. This article provides an overview of the techniques involved with their strengths and weaknesses. Two points need to be stressed here: the modelling of processes like dissolution and the surface activity of nanoparticles, possibly under influence of ultraviolet light, or chemical transformation has so far received relatively little attention. But also the uncertainties surrounding nanoparticles in general-the amount of nanoparticles used in consumer products, what constitutes the appropriate measure of concentration (mass or numbers) and what processes are relevant-should be explicitly considered as part of the modelling.

Sampling and simultaneous determination of volatile per- and polyfluoroalkyl substances in wastewater treatment plant air and water.

Volatile per- and polyfluoroalkyl substances (PFASs) are often used as precursors in the synthesis of nonvolatile PFASs. The volatile PFASs, which include the perfluoroalkyl iodides (PFAIs), fluorotelomer iodides (FTIs), fluorotelomer alcohols (FTOHs), fluorotelomer olefins (FTOs), fluorotelomer acrylates (FTACs), and fluorotelomer methacrylates (FTMACs), are often produced starting from the telomerization process. These volatile compounds can be present in the air and water environment and can be transformed into highly persistent perfluoroalkyl carboxylic acids. With the exception of FTOHs, which are well studied, the determination of other volatile PFASs is also of prime importance in studying the sources and fate of PFASs. In this study, a method was developed to determine representative precursor compounds that included PFAIs, FTIs, FTOs, FTACs, and FTMACs in wastewater treatment plant (WWTP) air and water samples. The sampling and sample preparation step involved the use of solid-phase extraction (SPE) cartridges with HLB™ material to enrich the analyte. Gas chromatography with mass spectrometry was employed for the detection and quantification of the analytes. Method validation results showed high linearity and sensitivity in the positive electron ionization-selected ion monitoring mode (+EI-SIM). The absolute instrumental limits of detection were in the range of 0.5 to 2 pg. The method detection limit (MDL) in air was 1 ng/m3 with the exception of the FTACs which could be only be detected at concentrations higher than 40 ng/m3. The MDL in water was 10 ng/L. Direct spiking of the cartridges and analyte introduction by volatilization from the glass surface onto the SPE material had recoveries between 86 and 100%. The volatile PFASs were shown to readily partition into the air rather than into water. Consequently, large losses in the amount of PFASs were observed when these were spiked into the water. Graphical abstract Wastewater treatment plant air and water samples were passed through HLB™ solid-phase materials. The eluates were injected onto a GC-MS system to simultaneously determine the volatile PFASs.

Effects of clay minerals, hydroxides, and timing of dissolved organic matter addition on the competitive sorption of copper, nickel, and zinc: A column experiment.

Infiltration of heavy metal (HM) polluted wastewater can seriously compromise soil and groundwater quality. Interactions between mineral soil components (e.g. clay minerals) and dissolved organic matter (DOM) play a crucial role in determining HM mobility in soils. In this study, the influence of the timing of addition of DOM, i.e. concurrent with or prior to HMs, on HM mobility was explored in a set of continuous flow column experiments using well defined natural soil samples amended with goethite, birnessite and/or smectite. The soils were subjected to concurrent and sequential additions of solutions of DOM, and Cu, Ni and Zn. The resulting breakthrough curves were fitted with a modified dose-response model to obtain the adsorption capacity (q0). Addition of DOM prior to HMs moderately enhanced q0 of Cu (8-25%) compared to a control without DOM, except for the goethite amended soil that exhibited a 10% reduction due to the blocking of binding sites. Meanwhile, for both Zn and Ni sequential addition of DOM reduced q0 by 1-36% for all tested soils due to preferential binding of Zn and Ni to mineral phases. In contrast, concurrent addition of DOM and HMs resulted in a strong increase of q0 for all tested metals and all tested soil compositions compared to the control: 141-299% for Cu, 29-102% for Zn and 32-144% for Ni. Our study shows that when assessing the impact of soil pollution through HM containing wastewater it is crucial to take into account the presence of DOM.

Transformation and Sorption of Illicit Drug Biomarkers in Sewer Systems: Understanding the Role of Suspended Solids in Raw Wastewater.

Sewer pipelines, although primarily designed for sewage transport, can also be considered as bioreactors. In-sewer processes may lead to significant variations of chemical loadings from source release points to the treatment plant influent. In this study, we assessed in-sewer utilization of growth substrates (primary metabolic processes) and transformation of illicit drug biomarkers (secondary metabolic processes) by suspended biomass. Sixteen drug biomarkers were targeted, including mephedrone, methadone, cocaine, heroin, codeine, and tetrahydrocannabinol (THC) and their major human metabolites. Batch experiments were performed under aerobic and anaerobic conditions using raw wastewater. Abiotic biomarker transformation and partitioning to suspended solids and reactor wall were separately investigated under both redox conditions. A process model was identified by combining and extending the Wastewater Aerobic/anaerobic Transformations in Sewers (WATS) model and Activated Sludge Model for Xenobiotics (ASM-X). Kinetic and stoichiometric model parameters were estimated using experimental data via the Bayesian optimization method DREAM(ZS). Results suggest that biomarker transformation significantly differs from aerobic to anaerobic conditions, and abiotic conversion is the dominant mechanism for many of the selected substances. Notably, an explicit description of biomass growth during batch experiments was crucial to avoid significant overestimation (up to 385%) of aerobic biotransformation rate constants. Predictions of in-sewer transformation provided here can reduce the uncertainty in the estimation of drug consumption as part of wastewater-based epidemiological studies.

Comparison of pharmaceutical, illicit drug, alcohol, nicotine and caffeine levels in wastewater with sale, seizure and consumption data for 8 European cities.

BACKGROUND: Monitoring the scale of pharmaceuticals, illicit and licit drugs consumption is important to assess the needs of law enforcement and public health, and provides more information about the different trends within different countries. Community drug use patterns are usually described by national surveys, sales and seizure data. Wastewater-based epidemiology (WBE) has been shown to be a reliable approach complementing such surveys. METHOD: This study aims to compare and correlate the consumption estimates of pharmaceuticals, illicit drugs, alcohol, nicotine and caffeine from wastewater analysis and other sources of information. Wastewater samples were collected in 2015 from 8 different European cities over a one week period, representing a population of approximately 5 million people. Published pharmaceutical sale, illicit drug seizure and alcohol, tobacco and caffeine use data were used for the comparison. RESULTS: High agreement was found between wastewater and other data sources for pharmaceuticals and cocaine, whereas amphetamines, alcohol and caffeine showed a moderate correlation. methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) and nicotine did not correlate with other sources of data. Most of the poor correlations were explained as part of the uncertainties related with the use estimates and were improved with other complementary sources of data. CONCLUSIONS: This work confirms the promising future of WBE as a complementary approach to obtain a more accurate picture of substance use situation within different communities. Our findings suggest further improvements to reduce the uncertainties associated with both sources of information in order to make the data more comparable.

Identification of photosynthesis inhibitors of pelagic marine algae using 96-well plate microfractionation for enhanced throughput in effect-directed analysis.

Because of large-scale production and use of an increasing diversity of chemicals in modern society, estuarine and coastal waters may be contaminated with numerous substances. Some of these compounds have the potential to affect microalgae at the base of the pelagic food chain. Therefore, we identified the main chemical stressors that negatively affect the effective photosystem II efficiency (ϕPSII) in marine microalgae of the Dutch estuarine and coastal waters. An enhanced effect-directed analysis (EDA) was carried out by combining reversed-phase ultra performance liquid chromatography fractionation of extracts from passive samplers, followed by effect assessment using the pulse amplitude modulation fluorometry assay and chemical analysis of biologically active fractions using high-resolution mass spectrometry. This study focuses on a novel microfractionation technique using 96-well plates to enhance throughput in EDA, structure elucidation, and the analytical and effect confirmation of the compounds that are identified. Although there are numerous unknown compounds present in estuarine and coastal waters, our EDA study shows that atrazine, diuron, irgarol, isoproturon, terbutryn, and terbutylazine are the main contributors to the observed effect on the ϕPSII of marine microalgae.

Analysis of (functionalized) fullerenes in water samples by liquid chromatography coupled to high-resolution mass spectrometry.

One of the main challenges in environmental risk assessment of fullerenes is to develop analytical methods that detect and quantify fullerenes at low concentrations. In this paper we report on the development and optimization of a highly specific, robust, and relatively simple method for the quantitative determination of C60, C70, and six functionalized fullerenes, namely, [6,6]-phenyl-C61-butyric acid methyl ester, [6,6]-phenyl-C61-butyric acid butyl ester, [6,6]-phenyl-C61-butyric acid octyl ester, [6,6]-bis(phenyl)-C61-butyric acid methyl ester, [6,6]-thienyl-C61-butyric acid methyl ester, and [6,6]-phenyl-C71-butyric acid methyl ester ([70PCBM], in different aqueous matrixes. For this method fullerenes were extracted from the aqueous phase using solid-phase extraction (SPE), with subsequent analysis on a liquid chromatography-Orbitrap mass spectrometry (LC-Orbitrap MS) system. SPE was optimized by varying different conditions to improve recovery of all fullerenes. Different SPE column materials (C18, C18e, C8, CN) were tested, and recoveries appeared to be the highest for the C18-material. Recoveries were improved by adding NaCl to the water during extraction. Very low limit of detection (LOD) values were obtained for all compounds with this method, ranging from 0.17 ng/L for [70]PCBM to 0.28 ng/L for C60, and subsequent limit of quantitation (LOQ) values of 0.57-0.91 ng/L. Recoveries for the fullerenes were on average 120% in ultrapure and drinking water. Recoveries appeared to be lower, but still acceptable (e.g., >78%), in surface water. The developed approach is promising and will be applied, for example, in (1) environmental monitoring, (2) a more in-depth study of environmental fate and transformation products, and (3) studying water treatment efficiency of C60, C70, and the various functionalized fullerenes.

Evaluation of uncertainties associated with the determination of community drug use through the measurement of sewage drug biomarkers.

The aim of this study was to integrally address the uncertainty associated with all the steps used to estimate community drug consumption through the chemical analysis of sewage biomarkers of illicit drugs. Uncertainty has been evaluated for sampling, chemical analysis, stability of drug biomarkers in sewage, back-calculation of drug use (specific case of cocaine), and estimation of population size in a catchment using data collected from a recent Europe-wide investigation and from the available literature. The quality of sampling protocols and analytical measurements has been evaluated by analyzing standardized questionnaires collected from 19 sewage treatments plants (STPs) and the results of an interlaboratory study (ILS), respectively. Extensive reviews of the available literature have been used to evaluate stability of drug biomarkers in sewage and the uncertainty related to back-calculation of cocaine use. Different methods for estimating population size in a catchment have been compared and the variability among the collected data was very high (7-55%). A reasonable strategy to reduce uncertainty was therefore to choose the most reliable estimation case by case. In the other cases, the highest uncertainties are related to the analysis of sewage drug biomarkers (uncertainty as relative standard deviation; RSD: 6-26% from ILS) and to the back-calculation of cocaine use (uncertainty; RSD: 26%). Uncertainty can be kept below 10% in the remaining steps, if specific requirements outlined in this work are considered. For each step, a best practice protocol has been suggested and discussed to reduce and keep to a minimum the uncertainty of the entire procedure and to improve the reliability of the estimates of drug use.

Daphnid life cycle responses to new generation flame retardants.

Relatively hazardous brominated flame retardants (BFRs) are currently substituted with halogen-free flame retardants (HFFRs). Consequently, information on their persistence, bioaccumulation and toxicity (PBT) is urgently needed. Therefore, we investigated the chronic toxicity to the water flea Daphnia magna of two HFFRs, aluminum diethylphosphinate (ALPI) and 9,10-dihyro-9-oxa-10-phosphaphenanthrene-oxide (DOPO). The toxicity of ALPI increased from a 48 h LC50 of 18 mg L(-1) to a 21 day LC50 value of 3.2 mg L(-1), resulting in an acute-to-chronic ratio of 5.6. This may imply a change in classification from low to moderate toxicity. ALPI also affected sublethal life cycle parameters, with an EC50 of 2.8 mg L(-1) for cumulative reproductive output and of 3.4 mg L(-1) for population growth rate, revealing a nonspecific mode of action. DOPO showed only sublethal effects with an EC50 value of 48 mg L(-1) for cumulative reproductive output and an EC50 value of 73 mg L(-1) for population growth rate. The toxicity of DOPO to D. magna was classified as low and likely occurred above environmentally relevant concentrations, but we identified specific effects on reproduction. Given the low chronic toxicity of DOPO and the moderate toxicity of ALPI, based on this study only, DOPO seems to be more suitable than ALPI for BFR replacement in polymers.

Persistence, bioaccumulation, and toxicity of halogen-free flame retardants.

Polymers are synthetic organic materials having a high carbon and hydrogen content, which make them readily combustible. Polymers have many indoor uses and their flammability makes them a fire hazard. Therefore, flame retardants (FRs) are incorporated into these materials as a safety measure. Brominated flame retardants (BFRs), which accounted for about 21% of the total world market of FRs, have several unintended negative effects on the environment and human health. Hence, there is growing interest in finding appropriate alternative halogen-free flame retardants (HFFRs). Many of these HFFRs are marketed already, although their environ- mental behavior and toxicological properties are often only known to a limited extent, and their potential impact on the environment cannot yet be properly assessed. Therefore, we undertook this review to make an inventory of the available data that exists (up to September 2011) on the physical-chemical properties, pro- duction volumes, persistence, bioaccumulation, and toxicity (PBT) of a selection of HFFRs that are potential replacements for BFRs in polymers. Large data gaps were identified for the physical-chemical and the PBT properties of the reviewed HFFRs. Because these HFFRs are currently on the market, there is an urgent need to fill these data gaps. Enhanced transparency of methodology and data are needed to reevaluate certain test results that appear contradictory, and, if this does not provide new insights, further research should be performed. TPP has been studied quite extensively and it is clearly persistent, bioaccumulative, and toxic. So far, RDP and BDP have demonstrated low to high ecotoxicity and persistence. The compounds ATH and ZB exerted high toxicity to some species and ALPI appeared to be persistent and has low to moderate reported ecotoxicity. DOPO and MPP may be persistent, but this view is based merely on one or two studies, clearly indicating a lack of information. Many degradation studies have been performed on PER and show low persistence, with a few exceptions. Additionally, there is too l ittle information on the bioaccumulation potential of PER. APP mostly has low PBT properties; however, moderate ecotoxicity was reported in two studies. Mg(OH)2, ZHS, and ZS do not show such remarkably high bioaccumulation or toxicity, but large data gaps exist for these compounds also. Nevertheless, we consider the latter compounds to be the most promising among alternative HFFRs. To assess whether the presently reviewed HFFRs are truly suitable alternatives, each compound should be examined individually by comparing its PBT values with those of the relevant halogenated flame retardant. Until more data are available, it remains impossible to accurately evaluate the risk of each of these compounds, including the ones that are already extensively marketed.

Effects of high pressure and temperature conditions on the chemical fate of flowback water related chemicals.

Environmental risk assessment is generally based on atmospheric conditions for the modelling of chemical fate after entering the environment. However, during hydraulic fracturing, chemicals may be released deep underground. This study therefore focuses on the effects of high pressure and high temperature conditions on chemicals in flowback water to determine whether current environmental fate models need to be adapted in the context of downhole activities. Crushed shale and flowback water were mixed and exposed to different temperature (25-100 °C) and pressure (1-450 bar) conditions to investigate the effects they have on chemical fate. Samples were analysed using LC-HRMS based non-target screening. The results show that both high temperature and pressure conditions can impact the chemical fate of hydraulic fracturing related chemicals by increasing or decreasing concentrations via processes of transformation, sorption, degradation and/or dissolution. Furthermore, the degree and direction of change is chemical specific. The change is lower or equal to a factor of five, but for a few individual compounds the degree of change can exceed this factor of five. This suggests that environmental fate models based on surface conditions may be used for an approximation of chemical fate under downhole conditions by applying an additional factor of five to account for these uncertainties. More accurate insight into chemical fate under downhole conditions may be gained by studying a fluid of known chemical composition and an increased variability in temperature and pressure conditions including concentration, salinity and pH as variables.