Ultrapure Waters Research Articles

Treatment of Waters Having Different Ionic Composition and pH with Natural Zeolites from Bulgaria

The migration of 32 elements from natural zeolitized tuffs from the Beli Plast and Golobradovo deposits (Bulgaria) was determined in ultrapure, tap, mineral, and coal mine waters in order to evaluate their desorption and adsorption properties. The tuffs are Ca-K-Na and contain clinoptilolite (90 and 78wt.%, respectively), plagioclase, sanidine, opal-CT, mica, quartz, montmorillonite, goethite, calcite, ankerite, apatite, and monazite. The desorption properties are best revealed during the treatment of ultrapure, tap, and mineral water, whereas the adsorption properties are best manifested in coal mine water treatment. The concentrations of Al, Si, Fe, Na, Mn, F, K, Pb, and U increase in the treated ultrapure, tap, and mineral water, while the content of K, Be, Pb, and F increase in the treated mine water. The tuffs show selective partial or complete adsorption of Na, Mg, Sr, Li, Be, Mn, Fe, Co, Ni, Cu, Zn, Al, Pb, U, and SO42−. They demonstrate the ability to neutralize acidic and alkaline pH. Sources of F are presumed to be clinoptilolite and montmorillonite. The usage of zeolitized tuffs for at-home drinking water treatment has to be performed with caution due to the migration of potentially toxic and toxic elements.

Application of 3D printed scavengers for improving the accuracy of single-particle inductively coupled plasma mass spectrometry analyses of silver nanoparticles by dissolved silver removal

The determination of silver nanoparticles (Ag NPs) with single-particle inductively coupled plasma mass spectrometry can be severely interfered with coexisting dissolved silver causing high background signals, which can lead to inaccurate quantification of NP size and particle concentration. In this paper, chemically active and reusable 3D printed scavengers are applied for highly efficient dissolved silver removal in Ag NP dispersions, allowing more accurate determination of particle concentration and size. Selective laser sintering was used for constructing the porous 3D scavengers constituting of polystyrene used as a supporting material and ion-exchange material SiliaBond Tosic acid (TA), which were chosen based on their high dissolved silver extraction efficiency and ability to maintain original NP properties. The macroporous structure of the final 3D TA scavengers allowed Ag NPs to pass freely through the object without affecting their original properties. The efficient contact between the sample solution and the functional material resulted in rapid (ca. <1 min/sample), and highly efficient dissolved silver removal (≥98%). The 3D TA scavengers showed potential to be used for preconcentration of dissolved silver, and the retained dissolved silver can be eluted with a 0.5 mM solution of sodium thiosulphate with excellent recoveries (≥99%). Competitive adsorption of elements commonly found in natural waters (Ca, K, Mg, Na, S, Si, and Sr) were not found to affect the dissolved silver extraction efficiency. The developed pre-treatment method was applied for the determination of 30 nm Ag NPs in ultrapure and clear environmental waters with coexisting dissolved silver (0.2 μg kg−1). Whereas measurement of the samples as such led to a significant bias in NP sizing (up to +12% increase) and counting (up to −51% decrease), pre-treatment of samples with the functional 3D TA scavengers eliminated the interfering effect of dissolved silver. This resulted in significant improvement in NP detection and determination. Highly similar values were obtained for both NP mean size (30 ± 1 nm, <4% different) and concentration (<13% different) in all matrices studied as compared to samples in the absence of dissolved silver.

Optimization for method for elemental impurities in ultra-pure waters

Optimization for method for elemental impurities in ultra-pure waters

Detecting Traces of 17α-Ethinylestradiol in Complex Water Matrices

Hormones have a harmful impact on the environment and their detection in water bodies is an urgent matter. In this work, we present and analyze a sensor device able to detect traces of the synthetic hormone 17α-ethinylestradiol (EE2) below 10−9 M in media of different complexities, namely, ultrapure, mineral and tap waters. This device consists of solid supports with interdigitated electrodes without and with a polyethylenimine (PEI) and poly (sodium 4-styrenesulfonate) (PSS) layer-by-layer film deposited on it. Device response was evaluated through capacitance, loss tangent and electric modulus spectra and the data were analyzed by principal component analysis method. While the three types of spectra were demonstrated to be able to clearly discriminate the different media, loss tangent spectra allow for the detection of EE2 concentration, with a sensitivity of −0.072 ± 0.009 and −0.44 ± 0.03 per decade of concentration, for mineral and tap water, respectively. Detection limits values were found to be lower than the ones present in the literature and presenting values of 8.6 fM (2.6 pg/L) and of 7.5 fM (22.2 pg/L) for tap and mineral waters, respectively. Moreover, the obtained response values follow the same behavior with EE2 concentration in any medium, meaning that loss tangent spectra allow the quantification of EE2 concentration in aqueous complex matrices.

Impact of environmental factors on the sampling rate of β-blockers and sulfonamides from water by a carbon nanotube-passive sampler

Passive techniques are a constantly evolving approach to the long-term monitoring of micropollutants, including pharmaceuticals, in the aquatic environment. This paper presents, for the first time, the calibration results of a new CNTs-PSDs (carbon nanotubes used as a sorbent in passive sampling devices) with an examination of the effect of donor phase salinity, water pH and the concentration of dissolved humic acids (DHAs), using both ultrapure and environmental waters. Sampling rates (Rs) were determined for the developed kinetic samplers. It has been observed that the impact of the examined environmental factors on the Rs values strictly depends on the type of the analytes. In the case of β-blockers, the only environmental parameter affecting their uptake rate was the salinity of water. A certain relationship was noted, namely the higher the salt concentration in water, the lower the Rs values of β-blockers. In the case of sulfonamides, water salinity, water pH 7–9 and DHAs concentration decreased the uptake rate of these compounds by CNTs-PSDs. The determined Rs values differed in particular when the values obtained from the experiments carried out using ultrapure water and environmental waters were compared. The general conclusion is that the calibration of novel CNTs-PSDs should be carried out under physicochemical conditions of the aquatic phase that are similar to the environmental matrix.

Green Graphene-Chitosan Sorbent Materials for Mercury Water Remediation.

The development of new graphene-based nanocomposites able to provide synergistic effects for the adsorption of toxic heavy metals in realistic conditions (environment) is of higher demand for future applications. This work explores the preparation of a green nanocomposite based on the self-assembly of graphene oxide (GO) with chitosan (CH) for the remediation of Hg(II) in different water matrices, including ultrapure and natural waters (tap water, river water, and seawater). Starting at a concentration of 50 μg L–1, the results showed that GO–CH nanocomposite has an excellent adsorption capacity of Hg (II) using very small doses (10 mg L–1) in ultrapure water with a removal percentage (% R) of 97 % R after only two hours of contact time. In the case of tap water, the % R was 81.4% after four hours of contact time. In the case of river and seawater, the GO–CH nanocomposite showed a limited performance due the high complexity of the water matrices, leading to a residual removal of Hg(II). The obtained removal of Hg(II) at equilibrium in river and seawater for GO–CH was 13% R and 7% R, respectively. Our studies conducted with different mimicked sea waters revealed that the removal of mercury is not affected by the presence of NO3– and Na+ (>90% R of Hg(II)); however, in the presence of Cl–, the mercury removal was virtually nonexistent (1% R of Hg(II)), most likely because of the formation of very stable chloro-complexes of Hg(II) with less affinity towards GO–CH.

Mechanistic study on chlorine/nitrogen transformation and disinfection by-product generation in a UV-activated mixed chlorine/chloramines system

The conversion mechanisms of chlorine species (including free chlorine, monochloramine (NH2Cl), dichloramine, and total chlorine), nitrogen species (including ammonium (NH4+), nitrate (NO3−), and nitrite (NO2−)) as well as the formation of disinfection by-products (DBPs) in a UV-activated mixed chlorine/chloramines system in water were investigated in this work. The consumption rates of free chlorine and NH2Cl were significantly promoted in a HOCl/NH2Cl coexisting system, especially in the presence of UV irradiation. Moreover, the transformation forms of nitrogen in both ultrapure and HA-containing waters were considerably affected by UV irradiation and the mass ratio of free chlorine to NH2Cl. NO3− and NO2− can be easily produced under UV irradiation, and the removal efficiency of total nitrogen with UV was obvious higher than that without UV when the initial ratio of HOCl/NH2Cl was less than 1. The roles of different radicals in the degradation of free chlorine, NH2Cl and NH4+ were also considered in such a UV-activated mixed chlorine/chloramines system. The results indicated that OH• was important to the consumption of free chlorine and NH2Cl, and showed negligible influence on the consumption of NH4+. Besides, the changes of DOC and UV254 in HA-containing water in UV-activated mixed chlorine/chloramines system indicated that the removal efficiency of DOC (24%) was much lower than that of UV254 (94%). The formation of DBPs in a mixed chlorine/chloramines system was also evaluated. The yields of DBPs decreased significantly as the mass ratio of HOCl/NH2Cl varied from 1 : 0 to 0 : 1. Moreover, compared to the conditions without UV irradiation, higher DBPs yields and DBP-associated calculated toxicity were observed during the UV-activated mixed chlorine/chloramine process.

Removal of legacy PFAS and other fluorotelomers: Optimized regeneration strategies in DOM-rich waters

We present the first study investigating optimized regeneration strategies for anionic ion exchange (IX) resins during the removal of persistent per- and poly-fluoroalkyl substances (PFAS, including GenX) from surface and treated wastewater effluents. IX regeneration studies are of critical importance from environmental perspectives. Specifically, the knowledge is essential for water utilities who presently operate IX (for PFAS removal) in a single use-and-dispose mode. In this study, legacy PFAS such as PFOA/PFOS were tested along with other harmful short-chained PFAS (PFBA/PFBS) and other toxic perfluorinated substitutes (GenX). Studies were performed on synthetic water (spiked with Suwannee River Natural Organic Matter (SRNOM), Fulvic Acid (SRFA) and Humic Acid (SRHA)), surface water, and wastewater effluents, and the regeneration was performed in batch stirred reactors. The resin service life with and without regeneration was investigated in the presence of background organic matter. In ultra-pure waters, all PFAS (C0 ∼10 μg/L, concentrations similar to that of natural waters) were effectively removed for >100,000 Bed Volume (BV) of operation. This was reduced to ∼23,500 BV in the presence of SRNOM (C0 = 5 mg C/L), 20,500 BV in SRFA and 8500 BV in SRHA, after which the saturated resins required regeneration. More importantly, all resin breakthrough (PFAS> 70 ng/L) corresponded to > 90% resin site saturation (in meqs), an essential information for optimizing IX loading. The competitive dissolved organic matter (DOM) fractions were estimated to be approximately 5–9% of the initial DOC, as estimated by the IAST-EBC model. Finally, it was identified that IX regeneration efficiency improved with increasing brine contact time but effectiveness plateaued for brine concentrations above 10% (W/V). Nonetheless, a regeneration with 10% NaCl solution with a contact time of 2 h was found to be optimal for IX operations in synthetic and natural waters. Therefore, this study provides key knowledge essential for the scientific community and the water industry on optimizing IX operational parameters for DOM and PFAS removal and would be highly valuable for systems which presently operate IX in a use-and-dispose mode.

Graphene oxide/polyethyleneimine aerogel for high-performance mercury sorption from natural waters

The development of effective sorbent materials to remove mercury (Hg) from real waters is a challenge. Here, we report the simple preparation of high-performance GOPEI aerogel for Hg remediation by self-assembly of high branched polyethyleneimine (PEI) with elevated molecular weight (Mw = 750 k) and graphene oxide (GO) under acidic conditions (pH < 3). Our studies revealed that the improved dimensional stability of GOPEI aerogels, critical for their use as sorbent materials, was obtained for a ratio GO:PEI 3:1. A small amount (10 mg L−1) of GOPEI proved a highly efficiency for Hg removal from natural waters (tap (91%), river (90%) and sea (81%)) under realistic environmental concentrations (50 µg L−1), where the existence of co-ions and different Hg-speciation are usually inhibitory factors of a good removal efficiency. This excellent performance was attributed to the synergistic effect resultant from the interactions between GO and PEI, giving a high content of N-rich groups and negative zeta potential over a wide pH range (from 2 to 12). Kinetic modelling pointed to differences on the main mechanisms behind the Hg removal by GOPEI in ultrapure vs natural waters. In ultrapure water pseudo-first order, usually associated with physical sorption, showed to be the best fit according to Akaike's Information Criterion (99.8% of probability), while in natural waters pseudo-second order model performed better (51.5% to 99.9% of probability), suggesting that the sorption is likely to rely on chemical interactions between Hg ions and the functional groups of GOPEI. Furthermore, GOPEI showed to be easily regenerated, keeping its high removal performance after 3 successive sorption-desorption cycles.

Dual nanofibrillar-based bio-sorbent films composed of nanocellulose and lysozyme nanofibrils for mercury removal from spring waters

The present study explores the preparation of dual nanofibrillar-based bio-sorbent films composed of cellulose nanofibrils (CNFs) and lysozyme nanofibrils (LNFs) for application in the removal of Hg(II) from aqueous solutions. The free-standing films were fabricated via simple vacuum filtration of water suspensions of CNFs and LNFs and disclose good mechanical and thermal properties. The Hg(II) removal efficiency was evaluated by atomic fluorescence spectroscopy in ultra-pure and natural spring waters contaminated with environmental realistic levels of mercury (50 μg L−1). The removal efficiency is pH-dependent reaching a maximum of 99 % after 24 h at a pH value close to the isoelectric point of the protein. Under the experimental conditions, the sorption kinetics are well described by the pseudo-second-order and Elovich models, suggesting a chemisorption mechanism. These results demonstrate the ability of the dual nanofibrillar-based films to remove Hg(II) from water samples reaching a residual concentration lower than the guideline value for water intended for human consumption (1 μg L−1). Therefore, the CNFs/LNFs bio-sorbents might be a solution to treat low-concentrated mercury-contaminated waters.

Efficient removal of parabens from real water matrices by a metal-free carbon nitride photocatalyst.

Metal-free graphite-like carbon nitride (GCN-500) was obtained by thermal post-treatment of bulk polymeric carbon nitride at 500°C. The catalyst was thoroughly characterized by morphological, optical and textural analysis techniques. The efficiency of GCN-500 was evaluated under visible (λexc=417nm) LED excitation for the photocatalytic degradation of methyl-, ethyl- and propyl-paraben in different water matrices either isolated or in a mixture of the three compounds. The GCN-500 proved to be more efficient than the benchmark TiO2 P25, with complete conversion of the individual parabens within 20min of irradiation, contrasting with 120min needed for total degradation using TiO2. Experiments in the presence of selected scavengers confirmed the high importance of superoxide radicals in the photocatalytic oxidation of parabens using GCN-500. The effect of the nature of the aqueous matrix in the kinetics of the photocatalytic process was assessed using ultrapure, tap and river waters spiked with a mixture of the three parabens. Although still very efficient, the complexity of the real water samples turned the degradation process slower due to the presence of other components such as ions and dissolved organic matter. GCN-500 proved to be stable in a continuous-flow system using GCN-500 coated glass rings (GCN-500-GR) to remove MP, EP and PP from real water matrices.

Neonicotinoid insecticide hydrolysis and photolysis: Rates and residual toxicity

Neonicotinoid insecticides are the most widely used class of insecticides worldwide. Concern has grown over their widespread environmental presence and potential unintended adverse effects. The present study examined hydrolysis and photolysis reaction rates of neonicotinoids and assessed any residual toxicity of reaction products. Hydrolysis rates were tested between pH 4 and 10 and found to be base-catalyzed. Experiments revealed a nonelementary rate law for hydrolysis, with the hydroxide concentration raised to a power of 0.55 ± 0.09, which has implications for accurate prediction of environmental half-lives. Divalent metal ions (Cu2+ , Ni2+ , Zn2+ ) and minerals (kaolinite, goethite, TiO2 ) had no effect on hydrolysis rates. The hydrolysis rate in a natural water, however, was slower than that predicted by buffered experiments. Nitenpyram, imidacloprid, thiamethoxam, and clothianidin reacted via direct photolysis in both ultrapure and natural waters, with average quantum yields of 0.024 ± 0.001, 0.0105 ± 0.0002, 0.0140 ± 0.0002, and 0.0101 ± 0.0001, respectively. Acetamiprid primarily underwent indirect photolysis by reaction with OH· (1.7 ± [0.2] × 109 M-1 s-1 ). For all compounds, the urea derivative was the most commonly detected product in both hydrolysis and photolysis experiments. Using mosquito (Culex pipiens) larvae, no residual toxicity of reaction products was observed. Results indicate long environmental half-lives for the tested neonicotinoids, which may help to explain their ubiquitous presence in environmental matrices. Environ Toxicol Chem 2018;37:2797-2809. © 2018 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Probing trace levels of prometryn solutions: from test samples in the lab toward real samples with tap water

Growing food demand has been addressed by protecting crops from insects, weeds, and other organisms by increasing the application of pesticides, thus increasing the risk of environmental contamination. Many pesticides, such as the triazines, are poorly soluble in water and require trace detection methods, which are normally achieved with high-cost sophisticated chromatography techniques. Here, we combine surface-enhanced Raman scattering (SERS) with multidimensional projection techniques to detect the toxic herbicide prometryn in ultrapure, deionized, and tap waters. The SERS spectra for prometryn were recorded with good signal-to-noise ratio down to 5 × 10−12 mol/L in ultrapure water, approaching single-molecule levels, and 5 × 10−9 mol/L in tap water. The latter is one order of magnitude below the threshold allowed for drinking water. In addition to providing a fingerprint of prometryn molecules at low concentrations, SERS is advantageous compared to other methods since it does not require pretreatment or chemical separation. The multidimensional projection methods and the detection procedure with SERS are entirely generic, and may be extended to any other pesticide or water contaminants, thus allowing environmental control to be potentially low cost if portable Raman spectrophotometers are used.

Degradation of Sucralose by Peroxidation Assisted with Ultraviolet Radiation and Photo-Fenton

Substances discharged intobodies of water must be studied due to possible risk of contamination and consequent damage to nature and human health.Sucralose is an artificial sweetener widely used to produce diet food and beverage. Most of this substance is expelled intact fromthe human body; therefore, its concentration in rivers and wastewaters is increasing worldwide. In this work, sucralose degradation was performed using advanced oxidation processes (AOPs): peroxidation assisted by ultraviolet radiation (H 2 O 2 /UV), Fenton's reagent (Fe(II)/H 2 O 2 /H + ), and photo-Fenton (Fe(II)/H 2 O 2 /H + /UV). Mineralization of the sweetener was measured usingtotal organic carbon (TOC). In addition, AOPs were applied to different water matrices, such as ultrapure, synthetic, and surface waters. Experiments were performed to evaluate the toxicity of the solution during the degradation processes.

Application of special oligotrophic media for cultivation of bacterial communities originated from ultrapure water

Because of the selectivity of the commonly used media it is very difficult to cultivate bacteria inhabiting ultrapure waters under laboratory conditions. In this study 5 new media (synthetic and complex) were developed to reveal bacterial community of the ultrapure water originated from the water purification system of a Hungarian power plant which was studied already with using traditional media. Composition of the new media tends to reproduce the nutrient deficient conditions of the investigated water, therefore media were highly oligotrophic. Altogether 122 bacterial strains were isolated from the 5 different media. Based on ARDRA grouping 27 strains were chosen for the partial 16S rRNA gene sequence analysis. The results showed that the applied media strongly influence the composition of the cultivable bacterial community. A larger scale of α-Proteobacteria (Mesorhizobium spp., Ancylobacter sp., Methylobacterium sp.) and many Actinobacteria (Leifsonia sp., Microbacterium spp., Mycobacterium spp.) could be isolated from the same ultrapure water system than with any other cultivation methods or media applied before. Moreover, two novel bacterial taxa could be isolated from the studied water purification system.

Degradation of progestagens by oxidation with potassium permanganate in wastewater effluents

BackgroundThis study investigated the oxidation of selected progestagenic steroid hormones by potassium permanganate at pH 6.0 and 8.0 in ultrapure water and wastewater effluents, using bench-scale assays. Second order rate constants for the reaction of potassium permanganate with progestagens (levonorgestrel, medroxyprogesterone, norethindrone and progesterone) was determined as a function of pH, presence of natural organic matter and temperature. This work also illustrates the advantages of using a novel analytical method, the laser diode thermal desorption (LDTD-APCI) interface coupled to tandem mass spectrometry apparatus, allowing for the quick determination of oxidation rate constants and increasing sample throughput.ResultsThe second-order rate constants for progestagens with permanganate determined in bench-scale experiments ranged from 23 to 368 M-1 sec-1 in both wastewater and ultrapure waters with pH values of 6.0 and 8.0. Two pairs of progestagens exhibited similar reaction rate constants, i.e. progesterone and medroxyprogesterone (23 to 80 M-1 sec-1 in ultrapure water and 26 to 149 M-1 sec-1 in wastewaters, at pH 6.0 and 8.0) and levonorgestrel and norethindrone (179 to 224 M-1 sec-1 in ultrapure water and 180 to 368 M-1 sec-1 in wastewaters, at pH 6.0 and 8.0). The presence of dissolved natural organic matter and the pH conditions improved the oxidation rate constants for progestagens with potassium permanganate only at alkaline pH. Reaction rates measured in Milli-Q water could therefore be used to provide conservative estimates for the oxidation rates of the four selected progestagens in wastewaters when exposed to potassium permanganate. The progestagen removal efficiencies was lower for progesterone and medroxyprogesterone (48 to 87 %) than for levonorgestrel and norethindrone (78 to 97%) in Milli-Q and wastewaters at pH 6.0-8.2 using potassium permanganate dosages of 1 to 5 mg L-1 after contact times of 10 to 60 min.ConclusionThis work presents the first results on the permanganate-promoted oxidation of progestagens, as a function of pH, temperature as well as NOM. Progestagen concentrations used to determine rate constants were analyzed using an ultrafast laser diode thermal desorption interface coupled to tandem mass spectrometry for the analysis of water sample for progestagens.

Determination of methyl mercury and inorganic mercury in natural waters at the pgL−1level: Intercomparison between PT-GC-Pyr-AFS and GC-ICP-MS using Ethylation or Propylation derivatization

Mercury speciation analysis of both inorganic and methyl Hg in ultrapure and natural waters by purge-and-trap gas chromatography pyrolysis atomic florescence spectrometry (PT-GC-Pyr-AFS, MERX-M, Brooks Rand) was performed. This automated analytical setup was also compared with gas chromatography inductively coupled plasma mass spectrometry (GC-ICPMS, X Serie 2 ThermoFisher). In addition, a reagent cleaning step of the buffer solution and derivatizing reagents (NaBEt4 and NaBPr4) was evaluated to improve the detection limit of the method. PT-GC-Pyr-AFS experiments analyzing Milli-Q and Deionized water (Millipore) using cleaned reagents and quantifying by external calibration led to MeHg + and Hg 2+ concentration values significantly lower than those obtained using uncleaned reagents. The limit of detections (LODs) after cleaning was found significantly low using both NaBEt4 and NaBPr4. However, the lowest LODs were obtained when using cleaned NaBPr4 (range: 1-2 pgL -1 for MeHg + and 9-10 pgL -1 for Hg 2+ ).

Elimination of the Emerging Contaminants Amitriptyline Hydrochloride, Methyl Salicylate, and 2-Phenoxyethanol in Ultrapure Water and Secondary Effluents by Photolytic and Radicalary Pathways

Chemical degradation of the pharmaceuticals and personal care products (PPCPs) amitriptyline hydrochloride, methyl salicylate, and 2-phenoxyethanol by means of several advanced oxidation processes, including 254 nm UV radiation and Fenton’s reagent, has been studied in different water matrixes, such as ultrapure (UP) and surface waters and two secondary effluents from wastewater treatment plants. The influence of the operating variables on the elimination of these compounds in UP water was established, and kinetic parameters for their degradation, such as quantum yields along a pH range of 3–11 and second-order rate constants for their oxidation by hydroxyl radicals, were determined. Specifically, for the reactions of oxidation of the three PPCPs with hydroxyl radicals, the use of a competition kinetic model in Fenton’s reagent experiments allowed evaluation of their rate constants, whose values were (10.3 ± 0.3) × 109 M–1·s–1 for amitriptyline hydrochloride, (7.1 ± 0.1) × 109 M–1·s–1 for methyl salicylat...

Bacterial communities in an ultrapure water containing storage tank of a power plant

Ultrapure waters (UPWs) containing low levels of organic and inorganic compounds provide extreme environment. On contrary to that microbes occur in such waters and form biofilms on surfaces, thus may induce corrosion processes in many industrial applications. In our study, refined saltless water (UPW) produced for the boiler of a Hungarian power plant was examined before and after storage (sampling the inlet [TKE] and outlet [TKU] waters of a storage tank) with cultivation and culture independent methods. Our results showed increased CFU and direct cell counts after the storage. Cultivation results showed the dominance of aerobic, chemoorganotrophic α-Proteobacteria in both samples. In case of TKU sample, a more complex bacterial community structure could be detected. The applied molecular method (T-RFLP) indicated the presence of a complex microbial community structure with changes in the taxon composition: while in the inlet water sample (TKE) α-Proteobacteria (Sphingomonas sp., Novosphingobium hassiacum) dominated, in the outlet water sample (TKU) the bacterial community shifted towards the dominance of α-Proteobacteria (Rhodoferax sp., Polynucleobacter sp., Sterolibacter sp.), CFB (Bacteroidetes, formerly Cytophaga-Flavobacterium-Bacteroides group) and Firmicutes. This shift to the direction of fermentative communities suggests that storage could help the development of communities with an increased tendency toward corrosion.

Non-catalytic and catalytic wet air oxidation of pharmaceuticals in ultra-pure and natural waters

A wet air oxidation (WAO) process was applied to four selected pharmaceuticals (metoprolol, naproxen, amoxicillin, and phenacetin) individually dissolved in ultra-pure water, varying the temperature and oxygen pressure. Due to the moderate (amoxicillin) or low (metoprolol, naproxen, and phenacetin) efficiency found in the oxidation of these pollutants, a catalytic wet air oxidation (CWAO) process was then tested using a platinum catalyst supported on multi-walled carbon nanotubes (CNT). In this CWAO process, the pharmaceuticals were dissolved together in ultra-pure water and in four natural water matrices—a reservoir water, a groundwater, and two waters from different municipal wastewater treatment plants. On the basis of the measurements of their removals, a discussion is given of the influence of the main operating variables: the presence or absence of catalyst, type of catalyst (the synthesized Pt/CNT or a commercial Pt/AC), catalyst dosage (0.005–0.050 g), temperature (120–140 °C), and oxygen pressure (20–40 bar). In most experiments, the removals were in the sequence: amoxicillin > naproxen > phenacetin. In addition, total organic carbon (TOC) removal measurements were made of some of the natural waters tested.