Efficiency of ozonation and sulfate radical - AOP for removal of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates.

This study investigated the elimination of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates during ozonation and UV/persulfate processes. Second-order rate constants for the reactions of candesartan, irbesartan, methyl-benzotriazole, and chloro­benzotriazole with sulfate radical (SO4·-) were determined for the first time. Experiments were conducted in buffered pure water, in buffered water added with the matrix substituents chloride, carbonate, NOM, and reverse osmosis concentrate with spiked micropollutants (MP). UV/persulfate eliminated all MP to a higher extent than ozonation in RO concentrates due to the higher yield of oxidative species and photolytic degradation. Compounds with electron-rich moieties such as carbamazepine, diclofenac, metoprolol, and sulfamethoxazole were completely eliminated with small ozone doses (< 0.5 mg O3 / mg DOC) and with a small fluence (< 5000 J m-2) in UV/persulfate processes. Photosensitive compounds with high reactivity towards hydroxyl radicals (·OH) and SO4·- like the x-ray contrast media Iopamidol, Iohexol, and Amidotrizoic acid were successfully eliminated with a reasonable fluence in UV/persulfate, whereas these compounds persist in ozonation at common ozone dosages. However, much higher fluences and ozone dosages were required for the least reactive compounds like the class of benzotriazoles. Comparing the application of both oxidative processes to the RO concentrate, ozonation has the disadvantage of forming bromate. The energy input of both processes strongly depends on the target compounds to be eliminated. For the elimination of compounds such as sulfamethoxazole, ozonation is a feasible technique, whereas UV/persulfate is better suited for the elimination of recalcitrant compounds such as x-ray contrast media. In general, oxidative process treatment of RO concentrate could be applied to partly abate micropollutants before discharge.

Evaluation of GC-EI&CI-TOFMS for Nontarget Analysis of Industrial Wastewater Using Hydrophilic-Lipophilic-Balanced SPME.

The evaluation of nontarget analysis (NTA) techniques for the monitoring of wastewater is important as wastewater is an anthropogenic pollution source for aquatic ecosystems and a threat to human and environmental health. This study presents the proof-of-concept NTA of industrial wastewater samples. A prototype hydrophilic-lipophilic-balanced (HLB) SPME and gas chromatography interfaced with time-of-flight high-resolution mass spectrometry (GC-TOFMS) with electron ionization (EI) and chemical ionization (CI) in parallel are employed. The HLB-SPME consists of a poly(divinylbenzene-co-N-vinylpyrrolidone) structure, allowing the extraction of hydrophilic as well as lipophilic substances. As the combination of parallel CI and EI data provides a comprehensive data set as a unique feature, this study is strongly focused on the compound identification procedure and confidence reporting of exemplary substances. Furthermore, the use of three different CI reagent ions, including [N2H]+/[N4H]+, [H3O]+, and [NH4]+, enables a broad range of analytes to be ionized in terms of selectivity and softness. The complementary information provided by EI and CI data allows a level 3 identification or higher in 69% of cases. The polarity coverage based on the physicochemical properties of the analytes (such as volatility, water solubility, hydrophilicity, and lipophilicity) was visualized by using Henry's law and octanol-water partitioning constants. In conclusion, the presented approach is shown to be valuable for water analysis and allows enhanced and accelerated compound identification compared to utilizing only one type of ionization.

qPeaks: A Linear Regression-Based Asymmetric Peak Model for Parameter-Free Automatized Detection and Characterization of Chromatographic Peaks in Non-Target Screening Data.

We present qPeaks (quality peaks), a novel, user-parameter-free algorithm for peak detection and peak characterization applicable to chromatographic data. The algorithm is based on a linearizable regression model that analyzes asymmetric peaks and estimates the specific uncertainties associated with the peak regression parameters. The uncertainties of the parameters are used to derive a data quality score DQSpeak, rendering low reliability results more transparent during processing and allowing for the prioritization of generated features. High DQSpeak chromatographic peaks have a lower chance of being classified as false-positive and show higher repeatability over multiple measurements. The high efficiency of the algorithm makes it particularly useful for application within processing routines of nontarget screening through chromatography coupled with high-resolution mass spectrometry. qPeaks is integrated into the qAlgorithms nontarget screening processing toolbox and appends a parameter-free chromatographic peak detection and characterization step to it. With qAlgorithms, now high-resolution mass spectra are centroided using the qCentroids algorithms, centroids are clustered to form extracted ion chromatograms (EICs) with the qBinning algorithm, and chromatographic peaks are found on the generated EICs with qPeaks. However, all tools from qAlgorithms can also be used independently.

Exploring the efficacy of metabarcoding and non-target screening for detecting treated wastewater.

Wastewater treatment processes can eliminate many pollutants, yet remainder pollutants contain organic compounds and microorganisms released into ecosystems. These remainder pollutants have the potential to adversely impact downstream ecosystem processes, but their presence is currently not being monitored. This study was set out with the aim of investigating the effectiveness and sensitivity of non-target screening of chemical compounds, 18S V9 rRNA gene, and full-length 16S rRNA gene metabarcoding techniques for detecting treated wastewater in receiving waters. We aimed at assessing the impact of introducing 33 % treated wastewater into a triplicated large-scale mesocosm setup during a 10-day exposure period. Discharge of treated wastewater significantly altered the chemical signature as well as the microeukaryotic and prokaryotic diversity of the mesocosms. Non-target screening, 18S V9 rRNA gene, and full-length 16S rRNA gene metabarcoding detected these changes with significant covariation of the detected pattern between methods. The 18S V9 rRNA gene metabarcoding exhibited superior sensitivity immediately following the introduction of treated wastewater and remained one of the top-performing methods throughout the study. Full-length 16S rRNA gene metabarcoding demonstrated sensitivity only in the initial hour, but became insignificant thereafter. The non-target screening approach was effective throughout the experiment and in contrast to the metabarcoding methods the signal to noise ratio remained similar during the experiment resulting in an increasing relative strength of this method. Based on our findings, we conclude that all methods employed for monitoring environmental disturbances from various sources are suitable. The distinguishing factor of these methods is their ability to detect unknown pollutants and organisms, which sets them apart from previously utilized approaches and allows for a more comprehensive perspective. Given their diverse strengths, particularly in terms of temporal resolution, these methods are best suited as complementary approaches.

qBinning: Data Quality-Based Algorithm for Automized Ion Chromatogram Extraction from High-Resolution Mass Spectrometry.

Due to the complexity and volume of data generated through non-target screening (NTS) using chromatographic couplings with high-resolution mass spectrometry, automized processing routines are necessary. The processing routines usually consist of many individual steps that are user-parameter-dependent and, thus, require labor-intensive optimization. Additionally, the effect of variations in raw data quality on the processing results is unclear and not fully understood. Within this work, we present qBinning, a novel algorithm for constructing extracted ion chromatograms (EICs) based on statistical principles and, thus, without the need to set user parameters. Furthermore, we give the user feedback on the specific qualities of the generated EICs using a scoring system (DQSbin). The DQSbin measures reliability as it correlates with the probability of correct classification of masses into EICs and the degree of overlap between different EIC construction algorithms. This work is a big step forward in understanding the behavior of NTS data and increasing the overall transparency in the results of NTS.

Oxidation of the N-containing phosphonate antiscalants NTMP and DTPMP in reverse osmosis concentrates: Reaction kinetics and degradation rate.

N-containing organophosphonate antiscalants such as Aminotris (methylene phosphonic acid) (NTMP/ATMP) and Diethylenetriamine penta(methylene phosphonic acid) (DTPMP) are commonly used in reverse osmosis (RO) to prevent scaling, as well as to increase permeate yields. However, the concentrate in RO still contains antiscalants which can cause adverse effects in the environment such as mobilization of heavy metals. The abatement of antiscalants from RO concentrate can promote the precipitation of oversaturated scale-forming substances and reduce the risk of adverse environmental effects. In the present study, the degradation of NTMP and DTPMP as representatives for N-containing organophosphonate by ozone, hydroxyl radicals (•OH), and sulfate radicals (SO4•-) are studied regarding reaction kinetics and degradation in different matrices. The results show that NTMP and DTPMP react fast with ozone and sulfate radicals (formed in UV/persulfate). Reaction rate constants of ozone showed a strong pH dependency due to the dissociation of the amine. The apparent reaction rates for pH 7 have been determined to be kapp(NTMP + ozone) = 1.44 × 105 M-1 s-1 and kapp(DTPMP + ozone) = 1.16 × 106 M-1 s-1. Reaction kinetics of •OH and SO4•- did not play a distinctive pH dependency (k(•OH) = 109-1010 M-1 s-1 and k(SO4•-) = 107-108 M-1 s-1). Furthermore, real water experiments have shown that ozonation and UV/persulfate are effective tools to abate organophosphonates in RO concentrates. The formation of carcinogenic bromate in ozonation is minimized by the presence of N-containing organophosphonates presumably due to enhanced ozone consumption and scavenging of free bromine.

Oxidation of the nitrogen-free phosphonate antiscalants HEDP and PBTC in reverse osmosis concentrates: Reaction kinetics and degradation rate.

Reverse osmosis (RO) is an advanced technology used to produce potable water from a variety of water sources, including surface water, seawater and wastewater. The yield of the product water from the RO systems is increased by the addition of antiscalants which prevent scaling from calcium and other ions. Removal of antiscalants from RO concentrate can induce the precipitation of oversaturated scale-forming substances, enable additional water recovery from RO concentrates, and reduce the risk of eutrophication after concentrate disposal into the receiving water (e.g., river water). This study aims to provide a better insight into oxidation reactions of the N-free phosphonate antiscalants 1-hydroxyethane-1,1-diphosphonic acid (HEDP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) with ozone, hydroxyl radical (•OH) and sulfate radicals (SO4•-). Ozone barely reacts with HEDP and PBTC at pH 7 (k < 10 M-1s - 1), while second order reaction rates of SO4•- and •OH were determined to be in the range 107-108M - 1s - 1. Sulfate, silicate and chloride matrices increased HEDP ozone degradation rate possibly due to metal complexation effect. Whereas carbonate and chloride hindered PBTC ozone degradation, and natural organic matter (NOM) inhibited both HEDP and PBTC degradation through scavenging of •OH. The SO4•-- radical based oxidation process of HEDP and PBTC is mainly inhibited by carbonate and NOM, interestingly only HEDP degradation is inhibited by chloride whereby the PBTC could not be fully degraded (degradation < 60%). The oxidation of PBTC is in real RO concentrates in both processes limited to 10% degradation, whereas HEDP could be degraded up to 60% with ozone and UV/persulfate application.

Non-target Analysis and Chemometric Evaluation of a Passive Sampler Monitoring of Small Streams.

Complex multivariate datasets are generated in environmental non-target screening (NTS) studies covering different sampling locations and times. This study presents a comprehensive chemometrics-based data processing workflow to reveal hidden data patterns and to find a subset of discriminating features between samples. We used ANOVA-simultaneous component analysis (ASCA) to disentangle the influence of spatial and seasonal effects as well as their interaction on a multiclass dataset. The dataset was obtained by a Chemcatcher passive sampler (PS) monitoring campaign of three small streams and one major river over four sampling periods from spring to summer. Monitoring of small streams is important as they are impacted by non-point source introduction of organic micropollutants (OMPs). The use of a PS provides a higher representativeness of sampling, and NTS broadens the range of detectable OMPs. A comparison of ASCA results of target analysis and NTS showed for both datasets a dominant influence of different sampling locations and individual temporal pollution patterns for each river. With the limited set of target analytes, general seasonal pollution patterns were apparent, but NTS data provide a more holistic view on site-specific pollutant loads. The similarity of temporal pollution patterns of two geographically close small streams was revealed, which was not observed in undecomposed data analysis like principal component analysis (PCA). With a complementary partial least squares-discriminant analysis (PLS-DA) and Volcano-based prioritization strategy, 223 site- and 45 season-specific features were selected and tentatively identified.