Spirulina-based carbon materials as adsorbents for drinking water taste and odor control: Removal efficiency and assessment of cyto-genotoxic effects.

The sensory quality of drinking water, and particularly its taste and odor (T&O) is a key determinant of consumer acceptability, as consumers evaluate water by their senses. Some of the conventional treatment processes to control compounds which impart unpleasant T&O have limitations because of their low efficiency and/or high costs. Therefore, there is a great need to develop an effective process for removing T&O compounds without secondary concerns. The primary objective of this study was to assess for the first time the effectiveness of spirulina-based carbon materials in removing geosmin (GSM) and 2-methylisoborneol (2-MIB) from water, two commonly occurring natural T&O compounds. The efficiency of the materials to remove environmentally relevant concentrations of GSM and 2-MIB (ng L-1) from ultrapure and raw water was investigated using a sensitive headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC/MS) method. Moreover, the genotoxic and cytotoxic effects of the spirulina-based materials were assessed for the first time to evaluate their safety and their potential in the treatment of water for human consumption. Based on the results, spirulina-based materials were found to be promising for drinking water treatment applications, as they did not exert geno-cytotoxic effects on human cells, while presenting high efficiency in removing GSM and 2-MIB from water.

Toxicity of butylone and its enantiomers to Daphnia magna and its degradation/toxicity potential using advanced oxidation technologies.

Butylone (BTL) is a chiral synthetic cathinone available as a racemate and reported as contaminant in wastewater effluents. However, there are no studies on its impact on ecosystems and possible enantioselectivity in ecotoxicity. This work aimed to evaluate: (i) the possible ecotoxicity of BTL as racemate or its isolated (R)- and (S)- enantiomers using Daphnia magna; and (ii) the efficiency of advanced oxidation technologies (AOTs) in the removal of BTL and reduction of toxic effects caused by wastewaters. Enantiomers of BTL were obtained by liquid chromatography (LC) using a chiral semi-preparative column. Enantiomeric purity of each enantiomer was > 97 %. For toxicity assessment, a 9-day sub-chronic assay was performed with the racemate (at 0.10, 1.0 or 10 µg L-1) or each enantiomer (at 0.10 or 1.0 µg L-1). Changes in morphophysiological, behavioural, biochemical and reproductive endpoints were observed, which were dependent on the form of the substance and life stage of the organism (juvenile or adult). Removal rates of BTL in spiked wastewater (10 µg L-1) treated with different AOTs (ultraviolet, UV; ozonation, O3; and UV/O3) were similar and lower than 29 %. The 48 h D. magna acute toxicity assays demonstrated a reduction in the toxicity of the treated spiked effluents, but no differences were found amongst AOTs treatments. These results warn for the contamination and negative impact of BTL on ecosystems and highlight the need for efficient removal processes.

Nanofiltration combined with ozone-based processes for the removal of antineoplastic drugs from wastewater effluents.

Over the past years, there has been an increasing concern about the occurrence of antineoplastic drugs in water bodies. The incomplete removal of these pharmaceuticals from wastewaters has been confirmed by several scientists, making it urgent to find a reliable technique or a combination of techniques capable to produce clean and safe water. In this work, the combination of nanofiltration and ozone (O3)-based processes (NF + O3, NF + O3/H2O2 and NF + O3/H2O2/UVA) was studied aiming to produce clean water from wastewater treatment plant (WWTP) secondary effluents to be safely discharged into water bodies, reused in daily practices such as aquaculture activities or for recharging aquifers used as abstraction sources for drinking water production. Nanofiltration was performed in a pilot-scale unit and O3-based processes in a continuous-flow column. The peroxone process (O3/H2O2) was considered the most promising technology to be coupled to nanofiltration, all the target pharmaceuticals being removed at an extent higher than 98% from WWTP secondary effluents, with a DOC reduction up to 92%. The applicability of the clean water stream for recharging aquifers used as abstraction sources for drinking water production was supported by a risk assessment approach, regarding the final concentrations of the target pharmaceuticals. Moreover, the toxicity of the nanofiltration retentate, a polluted stream generated from the nanofiltration system, was greatly decreased after the application of the peroxone process, which evidences the positive impact on the environment of implementing a NF + O3/H2O2 process.

Per- and Poly-Fluoroalkyl Substances in Portuguese Rivers: Spatial-Temporal Monitoring.

Eighteen per-and polyfluoroalkyl substances (PFASs) were investigated in surface waters of four river basins in Portugal (Ave, Leça, Antuã, and Cértima) during the dry and wet seasons. All sampling sites showed contamination in at least one of the seasons. In the dry season, perfluorooctanoate acid (PFOA) and perfluoro-octane sulfonate (PFOS), were the most frequent PFASs, while during the wet season these were PFOA and perfluobutane-sulfonic acid (PFBS). Compounds detected at higher concentrations were PFOS (22.6 ng L-1) and perfluoro-butanoic acid (PFBA) (22.6 ng L-1) in the dry and wet seasons, respectively. Moreover, the prospective environmental risks of PFASs, detected at higher concentrations, were evaluated based on the Risk Quotient (RQ) classification, which comprises acute and chronic toxicity. The results show that the RQ values of eight out of the nine PFASs were below 0.01, indicating low risk to organisms at different trophic levels in the four rivers in both seasons, wet and dry. Nevertheless, in the specific case of perfluoro-tetradecanoic acid (PFTeA), the RQ values calculated exceeded 1 for fish (96 h) and daphnids (48 h), indicating a high risk for these organisms. Furthermore, the RQ values were higher than 0.1, indicating a medium risk for fish, daphnids and green algae (96 h).

Gone with the flow - Assessment of personal care products in Portuguese rivers.

Although there are several works in the literature that study the presence of pharmaceuticals and personal care products (PPCPs) in surface waters, the vast majority focus their attention on pharmaceuticals and little information is found about personal care products (PCPs). Therefore, this study focused, for the first time, on the monitoring of five classes of PCPs - fragrance allergens, synthetic musks, phthalates, antioxidants, and ultraviolet-filters - in the surface water of four small-size typically pollution-impacted Portuguese rivers (Ave, Leça, Antuã and Cértima). A solid-phase microextraction (SPME) followed by gas chromatography - tandem mass spectrometry (GC-MS/MS) protocol was employed to analyse surface water samples collected in two seasonal campaigns - summer and winter (34 samples per season). A total of 22 out of 37 target PCPs were detected concomitantly at least once in one sampling point, being the most frequently detected α-isomethyl ionone, galaxolide, tonalide and cashmeran. The highest concentrations were confirmed for diethylhexyl phthalate (610.6 ng L-1), galaxolide (379.2 ng L-1), geraniol (290.9 ng L-1), linalool (271.2 ng L-1), benzophenone-3 (254.1 ng L-1) and citronellol (200.2 ng L-1). Leça River, traversing the more densely urban and industrialized area, had the highest levels of contaminants, which were also found in the sampling points located downstream of wastewater treatment plants discharge points. In general, higher levels were detected in summer, when the river flows are lower. Hazard quotients were determined and octocrylene, tonalide, and geraniol presented values above 1 in some sampling sites, which may indicate an ecotoxicological risk to the aquatic environment. The results presented suggest that these three PCPs should be included as priority pollutants in environmental monitoring schemes in surface waters, due to their high detection, persistence, and potential adverse effects.

Carbon xerogels combined with nanotubes as solid-phase extraction sorbent to determine metaflumizone and seven other surface and drinking water micropollutants.

Carbon xerogels (CXs) were synthesized by polycondensation of resorcinol and formaldehyde, followed by thermal annealing, and subjected to hydrothermal oxidation. Solid-phase extraction (SPE) cartridges were filled with CXs and tested for extraction of metaflumizone and other seven environmental micropollutants (acetamiprid, atrazine, isoproturon, methiocarb, carbamazepine, diclofenac, and perfluorooctanesulfonic acid) before chromatographic analysis. The recoveries obtained with the pristine CX were low for most analytes, except for metaflumizone (69 ± 5%). Moreover, it was concluded that the adsorption/desorption process of the micropollutants performed better on CXs with a less acidic surface (i.e., pristine CX). Thus, cartridges were prepared with pristine CX and multi-walled carbon nanotubes (MWCNTs) in a multi-layer configuration. This reusable cartridge was able to simultaneously extract the eight micropollutants and was used to validate an analytical methodology based on SPE followed by ultra-high performance liquid chromatography-tandem mass spectrometry. A widespread occurrence of 6/8 target compounds was observed in surface water collected in rivers supplying three drinking water treatment plants and in the resulting drinking water at the endpoint of each distribution system. Therefore, the first study employing CXs and MWCNTs as sorbent in multi-layer SPE cartridges is herein reported as a proof of concept for determination of multi-class water micropollutants.

Solid-phase extraction cartridges with multi-walled carbon nanotubes and effect of the oxygen functionalities on the recovery efficiency of organic micropollutants.

Pristine and functionalized multi-walled carbon nanotubes (MWCNTs) were investigated as adsorbent materials inside solid-phase extraction (SPE) cartridges for extraction and preconcentration of 8 EU-relevant organic micropollutants (with different pKa and polarity) before chromatographic analysis of surface water. The recoveries obtained were > 60% for 5/8 target pollutants (acetamiprid, atrazine, carbamazepine, diclofenac, and isoproturon) using a low amount of this reusable adsorbent (50 mg) and an eco-friendly solvent (ethanol) for both conditioning and elution steps. The introduction of oxygenated surface groups in the carbon nanotubes by using a controlled HNO3 hydrothermal oxidation method, considerably improved the recoveries obtained for PFOS (perfluorooctanesulfonic acid) and methiocarb, which was ascribed to the hydrogen bond adsorption mechanism, but decreased those observed for the pesticide acetamiprid and for two pharmaceuticals (carbamazepine and diclofenac), suggesting π-π dispersive interactions. Moreover, a good correlation was found between the recovery obtained for methiocarb and the amount of oxygenated surface groups on functionalized MWCNTs, which was mainly attributed to the increase of phenols and carbonyl and quinone groups. Thus, the HNO3 hydrothermal oxidation method can be used to finely tune the surface chemistry (and texture) of MWCNTs according to the specific micropollutants to be extracted and quantified in real water samples.

Distribution of micropollutants in estuarine and sea water along the Portuguese coast.

This work provides the first spatial distribution report of micropollutants (MPs) in the entire Portuguese coast, comprising the ocean shore (sea water, SW) and whenever possible the nearest river discharging on it (estuarine water, EW). This surface water monitoring programme aimed to assess the spatial distribution of 37 MPs with a wide chemical nature, including some substances prioritized by the European Union Directive 39/2013/EU and contaminants of emerging concern targeted in the Watch List of Decisions 495/2015/EU and 840/2018/EU. The risk quotients were estimated in each sampling point for the detected MPs. High concentrations of diclofenac, tramadol and carbamazepine were determined, the latter with medium to high risk for algae. Some pharmaceuticals and perfluorooctanesulfonic acid (PFOS) were broadly distributed, maybe due to the direct discharge into the sea. Atrazine and alachlor were found in the majority of the samples, with alachlor levels often considered as medium to high risk.

Quenchers in advanced oxidation technologies for analysis of micropollutants by liquid chromatography coupled to mass spectrometry: Sodium sulphite or catalase?

This work aimed to investigate the possible effect of 2 quenchers commonly used in H2O2-based advanced oxidation technologies (AOTs), i.e. catalase and sodium sulphite (Na2SO3), on the analytical signal of 3 detectors coupled to liquid chromatography (LC): tandem mass spectrometry (LC-MS/MS), fluorescence detection (LC-FD) and LC-diode array detection (LC-DAD). The observation of analytical interferences for a group of compounds when studying the removal by continuous mode UV/H2O2 of 26 micropollutants (MPs) from a spiked surface water (SW), for which the residual H2O2 in the samples was quenched by Na2SO3, triggered the need of understanding these effects and thus catalase was used as comparative quencher. From the 26 MPs having a wide range of polarity and pKa, those monitored after electrospray ionization (ESI) under positive ionization (PI) mode and presenting a pKa higher than 5.9 revealed a great signal suppression, but only when using Na2SO3 as H2O2 quencher. In this sense, we further explored this effect by selecting 2 MPs, metoprolol and diclofenac, which had respectively signal suppression and no interference in the LC-MS/MS response. These MPs were analysed before and after addition of H2O2 and catalase or Na2SO3 in reaction vials, using: (i) different detectors coupled to LC, namely LC-MS/MS with ESI under PI and negative ionization (NI) modes, LC-FD and LC-DAD; (ii) different environmental matrices (SW, drinking water, wastewater) and ultrapure water; and (iii) different magnitude levels (0.1-10 mg L-1). The results demonstrated a remarkable signal suppression in LC-MS/MS analyses under PI mode for those compounds with pKa higher than 5.9, confirming the interfering effect of H2O2/Na2SO3. To the best of our knowledge, the analytical interference in the LC-MS/MS analysis, after adding Na2SO3 to quench H2O2 in AOTs experiments was never reported before and the results presented herein support the recommendation to use catalase instead of Na2SO3 as quencher in AOTs studies.