Effluent Of Urban Wastewater Treatment Plant Research Articles

Pilot plant approach combining photocatalysis and adsorption for antibiotics removal from slaughterhouse and urban wastewater treatment plant effluents

The main objective of this research is to perform a real case-study of antibiotic decontamination from real slaughterhouse and wastewater effluents by applying a sequential treatment of TiO2/UV–vis photocatalysis and adsorption. More precisely, the removal of five classes of antibiotics: enrofloxacin, sulfadiazine, trimethoprim, azithromycin, amoxicillin and amoxicillin degradation products was studied in an 80 L/h photocatalytic and adsorption pilot-scale plant over multiple cycles, operating in semi-continuous mode. The results exhibited significant removal rates, ranging from 77% to 100% for the slaughterhouse effluent, and 61–89% for the wastewater treatment plant effluent, thus demonstrating that the treatment is more effective when it is applied directly in the emission source, previous to antibiotic dilution in the municipal collector. Using the two processes sequentially results in greater efficiency than when they are used in isolation. After photocatalysis, antibiotic degradation products are easily adsorbed, since they have more affinity for the adsorbent, and the presence of competing compounds decreases considerably. After applying several cycles of treatment, the adsorption performance remains almost constant. By contrast, the photocatalysis performance decreased, which was attributed to catalyst agglomeration determined by Asymmetric Flow Field-Flow Fractionation (AF4) coupled with Dynamic Light Scattering (DLS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

Characterization of phage vB_EcoS-EE09 infecting E. coli DSM613 Isolated from Wastewater Treatment Plant Effluent and Comparative Proteomics of the Infected and Non-Infected Host.

Phages influence microbial communities, can be applied in phage therapy, or may serve as bioindicators, e.g., in (waste)water management. We here characterized the Escherichia phage vB_EcoS-EE09 isolated from an urban wastewater treatment plant effluent. Phage vB_EcoS-EE09 belongs to the genus Dhillonvirus, class Caudoviricetes. It has an icosahedral capsid with a long non-contractile tail and a dsDNA genome with an approximate size of 44 kb and a 54.6% GC content. Phage vB_EcoS-EE09 infected 12 out of the 17 E. coli strains tested. We identified 16 structural phage proteins, including the major capsid protein, in cell-free lysates by protein mass spectrometry. Comparative proteomics of protein extracts of infected E. coli cells revealed that proteins involved in amino acid and protein metabolism were more abundant in infected compared to non-infected cells. Among the proteins involved in the stress response, 74% were less abundant in the infected cultures compared to the non-infected controls, with six proteins showing significant less abundance. Repressing the expression of these proteins may be a phage strategy to evade host defense mechanisms. Our results contribute to diversifying phage collections, identifying structural proteins to enable better reliability in annotating taxonomically related phage genomes, and understanding phage-host interactions at the protein level.

Assessment of new immobilized photocatalysts based on TiO2 for wastewater decontamination

With the main objective of overcoming the main drawbacks in the actual application of semiconductors in slurry in solar photocatalysis, new immobilized photocatalysts based on TiO2 supported on glass wool and silica material have been evaluated for tertiary/quaternary treatment of urban wastewater treatment plant effluents. Preliminary tests were carried out under different operating conditions in a solar simulator SUNTEST XLS+ with 30 W/m2 irradiation average. Demineralized water was spiked with sulfamethoxazole (SMX) (at 1 mg/L initial concentration) as water model pollutant. The mere effect of only irradiance as well as the photocatalytic performance of TiO2-P25 in slurry over SMX abatement were also investigated as references. The highest SMX removal (> 98% in 25 min) was obtained with SiO2_TiO2 photocatalyst (0.5 g/L). The efficacy of SiO2_TiO2 was demonstrated to be stable for 5 cycles of reusing and 66% of mineralization was also obtained through the degradation of 25 mg/L of SMX after 360 min of treatment. SiO2_TiO2 photocatalyst was also assessed for the elimination of SMX present in a more complex water matrix, in simulated urban wastewater, obtaining 50% of SMX removal in 120 min. In addition, 7 transformation products (TPs) were identified by UPHLC-QTOF-MS/MS and a tentative degradation pathway was elucidated. Assessment on actual implementation of supported TiO2 photocatalysts in solar photoreactors must be tackled in the future.

Application of g-C3N4-PVDF membrane for the photocatalytic degradation of micropollutants in continuous flow mode: Impact of water matrix

The combination of photocatalysis with membrane separation technology allows to mitigate potential membrane fouling while degrading the organic micropollutants in water. This work is focused on the immobilization of a g-C3N4 promising photocatalyst, in the form of a g-C3N4-PVDF polymeric membrane, for the elimination of representative pharmaceutical substances from complex water matrices in a continuous flow mode under visible light irradiation. Metoprolol (MTP), venlafaxine (VEN) and diclofenac (DCF) in a mixture (at 250 μg L−1 each) were fed to the system at room temperature. The adsorption of these substances on the membrane was negligible (< 5%) in the dark. Removals of 89%, 92% and 72% for MTP, VEN and DCF, respectively, were achieved in deionized water using visible-light emitting diodes (LEDs) as light source. Moreover, the permeate flux remained constant throughout the experiments (89.5 L m−2 h−1). The membrane system was then assessed using urban wastewater treatment plant effluent, surface and tap waters, spiked with the target analytes. As expected, a worse performance was observed with these matrices, although still high removals were achieved in tap water (73%, 61% and 75%, respectively for MTP, VEN and DCF). Accordingly, the impact of the occurrence of humic acid as representative species of natural organic matter, as well as inorganic ions such as chlorides, sulphates, phosphates and carbonates, was evaluated in more detail. Clearly, humic acid and sulphates were the most impactful on the treatment performance. Finally, different scavengers were used to understand the photocatalytic mechanism, suggesting that superoxide radicals and photogenerated holes were the main active species involved in the removal of the studied micropollutants.

Comprehensive Genome and Plasmidome Analysis of Antimicrobial Resistant Bacteria in Wastewater Treatment Plant Effluent of Tokyo.

To characterize environmental antimicrobial resistance (AMR) in urban areas, extended-spectrum β-lactamase- (ESBL)/carbapenemase-producing bacteria (EPB/CPB, respectively) from urban wastewater treatment plant effluents in Tokyo were isolated on CHROMagar ESBL plate. Complete genome sequence analysis, including plasmids, indicated that 126 CTX-M-positive isolates (31%) were identified among the 404 obtained isolates. The CTX-M-9 group was predominant (n = 65, 52%), followed by the CTX-M-1 group (n = 44, 35%). Comparative genome analysis revealed that CTX-M-27-positive E. coli O16:H5-ST131-fimH41 exhibited a stable genome structure and clonal-global dissemination. Plasmidome network analysis revealed that 304 complete plasmid sequences among 85 isolates were grouped into 14 incompatibility (Inc) network communities (Co1 to Co14). Co10 consisted of primarily IncFIA/IncFIB plasmids harboring blaCTX-M in E. coli, whereas Co12 consisted primarily of IncFIA(HI1)/Inc FIB(K) plasmids harboring blaCTX-M, blaKPC, and blaGES in Klebsiella spp. Co11 was markedly located around Co10 and Co12. Co11 exhibited blaCTX-M, blaKPC, and blaNDM, and was mainly detected in E. coli and Klebsiella spp. from human and animal sources, suggesting a mutual role of Co11 in horizontal gene transfer between E. coli and Klebsiella spp. This comprehensive resistome analysis uncovers the mode of relational transfer among bacterial species, highlighting the potential source of AMR burden on public health in urban communities.

A thermocatalytic perovskite-graphene oxide nanofiltration membrane for water depollution

A novel nanofiltration membrane, whose active layer consists of 98.6 wt% of a thermocatalytic perovskite with composition Sr0.85Ce0.15FeO3-δ (CSF), 1.0 wt% of graphene oxide (GO), and 0.4 wt% of a humic acid-like (HAL) crosslinker, was deposited over a commercial flat-sheet polyethersulfone support with good reproducibility by a simple 1-step coating procedure. The synergistic coupling of CSF and the crosslinked GO resulted in an improved catalytic activity for bisphenol A (BPA) abatement as a model pollutant. The thermocatalytic CSF/GO/HAL (GOT) membrane was tested in a nanofiltration crossflow apparatus with a model BPA solution and with a real urban wastewater treatment plant effluent. Its performances were compared with those of a HAL crosslinked GO (GOHAL) reference membrane. The GOT membrane presented high rejection towards BPA, antifouling properties, and stability under the filtration conditions. Moreover, when compared to the GOHAL reference, the thermocatalytic GOT membrane was able to reduce the concentration of BPA and the total organic carbon in the feed during filtration. Hence, the GOT membrane appears to have high potential in water treatment due to its multifunctional characteristics, which include molecular sieving, thermocatalytic oxidation of organic pollutants, and self-cleaning properties. Additionally, the membrane material showed no significant toxicity to the aquatic model organisms Raphidocelis subcapitata, Aliivibrio fischeri, and Daphnia magna at concentrations below 50 ppm.

Simultaneous disinfection and microcontaminants elimination of urban wastewater secondary effluent by solar advanced oxidation sequential treatment at pilot scale

The effect of different times of Fe:Ethylenediamine-N, N′-disuccinic acid (EDDS) dosing and H2O2 as well as different Fe:EDDS concentrations in the sequential treatment sunlight/H2O2 followed by sunlight/H2O2/Fe:EDDS at circumneutral pH was investigated for the first time focusing both in contaminants of emerging concern (CECs) and bacteria removal in urban wastewater treatment plant effluents. Process efficiency was evaluated in terms of (i) degradation of five CECs (namely caffeine, carbamazepine, diclofenac, sulfamethoxazole and trimethoprim) at the initial concentration of 100 μgL−1 each and (ii) bacteria inactivation (Escherichia coli (E. coli) and Salmonella spp). The effect of H2O2, Fe and EDDS concentration and Fe:EDDS dosing time was evaluated. 60% removal of the sum of total CECs and pathogens inactivation below the detection limit (DL) were observed by the sequential treatment with Fe:EDDS additions at 60 min and 45 min in simulated urban wastewater effluent. Sequential treatment was validated in actual urban wastewater effluent, being able to remove 60% of the target CECs and inactivate bacteria below the DL. Increasing EDDS concentration negatively affected Salmonella spp inactivation. Sequential treatment based on 120 min of sunlight/H2O2 (50 mg L−1) and subsequent SPF with Fe:EDDS (0.1:0.1 mM) was chosen as best operation conditions for full scale treatment in urban wastewater treatment plants.

Effect of ozonation on the biodegradability of urban wastewater treatment plant effluent

The present work aimed to study the effect of ozonation on the organic sum parameters linked to enhanced biodegradability. Laboratory experiments were conducted with the effluent of four Austrian urban wastewater treatment plants with low food to microorganism ratios and different matrix characteristics. Biochemical oxygen demand over 5 days (BOD5) was measured before ozonation and after application of different specific ozone doses (Dspec) (0.4, 0.6 and 0.8 g O3/g DOC). Other investigated organic parameters comprised chemical oxygen demand (COD), dissolved organic carbon (DOC), UV absorption at 254 nm (UV254), which are parameters that are applied in routine wastewater analysis. Carbamazepine and benzotriazole were measured as reference micropollutants. The results showed a dose-dependent increase in biological activity after ozonation; this increase was linked to the enhanced biodegradability of substances that are recalcitrant to biodegradation in conventional activated sludge treatment. The highest relative change was determined for BOD5, which already occurred between 0 and 0.4 g O3/g DOC for all samples. Increasing the Dspec to 0.6 and 0.8 g O3/g DOC resulted in a less pronounced increase. DOC was not substantially decreased after ozonation, which was consistent with a low reported degree of mineralization, while partial oxidation led to a quantifiable decrease in COD (7 to 17%). Delta UV254 and the decline in specific UV absorption after ozonation clearly correlated with Dspec. In contrast, for COD and biodegradable DOC (BDOC), a clear dose-response pattern was identified only after exposure to BOD5 measurement. Indications for improved biodegradability were further supported by the rise in the BOD5/COD ratio. The results indicated that subsequent biological processes have a higher degradation potential after ozonation. The further reduction in biodegradable organic carbon emission by the combination of ozonation and biological post treatment represents another step towards sustainable water resource management in addition to micropollutant abatement.

Removal of Organic UV Filters Using Enzymes in Spent Mushroom Composts from Fungicultures

Organic UV filters in sunscreen products are released to aquatic ecosystems through human recreational activities and urban wastewater treatment plant effluents. The biodegradation of three organic UV filters, 2-ethylhexyl salicylate (EHS), homosalate (HMS) and ethylhexyl methoxycinnamate (EHMC), which cannot be effectively removed by conventional wastewater treatment plants, was investigated in this study. Spent mushroom compost (SMC), a waste product of the mushroom industry, which contains white-rot fungus extracellular enzymes, was tested for its ability to remove the three organic UV filters. The results of batch experiments revealed that the SMC enzyme extract of Pleurotus djamor exhibited the highest ability for EHS and HMS removal. The results of bioreactor experiments indicated that direct application of SMCs may be a feasible solution to remove EHS and HMS from urban wastewater. The application of SMCs for the removal of organic UV filters can be developed into a green and sustainable technology.

Ecotoxicological risk assessment of contaminants of emerging concern identified by "suspect screening" from urban wastewater treatment plant effluents at a territorial scale.

Urban wastewater treatment plants (WWTP) are a major vector of highly ecotoxic contaminants of emerging concern (CECs) for urban and sub-urban streams. Ecotoxicological risk assessments (ERAs) provide essential information to public environmental authorities. Nevertheless, ERAs are mainly performed at very local scale (one or few WWTPs) and on pre-selected list of CECs. To cope with these limits, the present study aims to develop a territorial-scale ERA on CECs previously identified by a "suspect screening" analytical approach (LC-QToF-MS) and quantified in the effluents of 10 WWTPs of a highly urbanized territory during three periods of the year. Among CECs, this work focused on pharmaceutical residue and pesticides. ERA was conducted following two complementary methods: (1) a single substance approach, based on the calculation for each CEC of risk quotients (RQs) by the ratio of Predicted Environmental Concentration (PEC) and Predicted No Effect Concentration (PNEC), and (2) mixture risk assessment ("cocktail effect") based on a concentration addition model (CA), summing individual RQs. Chemical results led to an ERA for 41 CEC (37 pharmaceuticals and 4 pesticides) detected in treated effluents. Single substance ERA identified 19 CECs implicated in at least one significant risk for streams, with significant risks for DEET, diclofenac, lidocaine, atenolol, terbutryn, atorvastatin, methocarbamol, and venlafaxine (RQs reaching 39.84, 62.10, 125.58, 179.11, 348.24, 509.27, 1509.71 and 3097.37, respectively). Mixture ERA allowed the identification of a risk (RQmix > 1) for 9 of the 10 WWTPs studied. It was also remarked that CECs leading individually to a negligible risk could imply a significant risk in a mixture. Finally, the territorial ERA showed a diversity of risk situations, with the highest concerns for 3 WWTPs: the 2 biggest of the territory discharging into a large French river, the Rhône, and for the smallest WWTP that releases into a small intermittent stream.

Effect of salinity on preconcentration of contaminants of emerging concern by nanofiltration: Application of solar photo-Fenton as a tertiary treatment

This study focused on the effect of salinity on the performance of a pilot-scale nanofiltration (NF) for preconcentration of microcontaminants (MCs) in combination with solar photo-Fenton or photo-Fenton-like treatment for their elimination from NF permeate and concentrate streams. Photo-Fenton was carried out in a solar simulator at pH of 3 and at natural pH using Ethylenediamine-N, N′-disuccinic acid (EDDS) as an iron complexing agent. Degradation efficacy was tested with MCs commonly found in urban wastewater treatment plant effluents (caffeine, imidacloprid, thiacloprid, carbamazepine and diclofenac). Hydrogen peroxide and persulfate were compared in solar processes. Increase in salinity and pressure had a negligible influence on MC permeability order and NF selectivity. Solar photo-Fenton was able to degrade MCs present in the concentrated stream, and rapidly eliminate any residual MCs that might finally be present in permeate streams. Persulfate used instead of hydrogen peroxide was shown to be inefficient for the selected MCs. Fe(III):EDDS at circumneutral pH was able to remove MCs as quickly as classical photo-Fenton at acid pH, or even faster. This effect supports use of Fe(III):EDDS at natural pH for treating NF concentrates or polishing NF permeates when NF membranes are operated under extreme conditions of salinity.

Exploring the Efficiency of UHPLC-Orbitrap MS for the Determination of 20 Pharmaceuticals and Acesulfame K in Hospital and Urban Wastewaters with the Aid of FPSE

Aside from the classical residues of persistent organic pollutants (POPs), the occurrence of emerging contaminants (ECs) in the environment has become a subject of increasing concern due to their harmful impact on the aquatic environment. Wastewater treatment plant (WWTP) effluents are major sources of environmental pollution. Therefore, data concerning their existence is required. In this study, twenty compounds representative of different drug groups considered ECs and belonging to antibiotics, antipsychotics, anti-inflammatory drugs plus acesulfame K were selected to be accurately detected and quantified with UHPLC–LTQ-Orbitrap MS in hospital and urban WWTP effluents. Chromatographic parameters (column efficiency, mobile phase, etc.), as well as mass spectrometry conditions concerning ionization mode and Orbitrap analysis (ESI options, mass resolving power, AGC target, tube lens, injection time), were evaluated. Moreover, a novel fabric phase sorptive extraction (FPSE) method based on fiber glass coated with PEG300 was employed as sample preparation process. Experimental parameters affecting extraction and desorption steps such as sample pH, extraction time, ionic strength, elution time and solvent have been optimized. The optimized methodology was validated providing excellent linearity (R2 &gt; 0.99), and low detection and quantification limits up to 3.1 and 9.3 ng/L, for carbamazepine, respectively. Relative recoveries ranged from 81.1% to 114.0%, while a medium matrix effect for most of the target compounds occurred. Applying the above analytical method in effluents of WWTPs from NW Greece, nine compounds were quantified with concentrations that varied from 55.4 to 728.4 ng/L.

Nanofiltration retentate treatment from urban wastewater secondary effluent by solar electrochemical oxidation processes

Comparison of electrochemical processes at pilot plant scale for the elimination of organic microcontaminants in actual urban wastewater treatment plant secondary effluents pre-treated by nanofiltration ([Cl−] = 1100–2000 mg L−1) membranes (for reducing total volume to be treated and increase water salinity), has been addressed. Anodic oxidation (AO), solar-assisted AO, electro Fenton (EF) and solar photoelectro-Fenton (SPEF) processes have been evaluated by using, when required, ethylenediamine-N,N’-disuccinic acid (EDDS) as complexing agent to maintain iron in solution at natural pH. Target water was spiked with a mix solution of microcontaminants: pentachlorophenol, terbutryn, chlorfenvinphos and diclofenac at initial concentrations of 500 and 100 μg L−1, each. AO and EF processes obtained similar degradation rates as added EDDS competed with microcontaminants for oxidant species. SPEF and solar assisted AO showed that high chloride concentrations was a crucial factor since chlorine species generated by solar-assisted AO were enough for efficient microcontaminant removal avoiding the addition of EDDS. Degradation monitoring of microcontaminants contained in actual urban wastewater treatment plant effluents was carried out by liquid chromatography coupled to hybrid quadrupole-linear ion trap-mass spectrometry.

Photocatalytic degradation of pharmaceutically active compounds (PhACs) in urban wastewater treatment plants effluents under controlled and natural solar irradiation using immobilized TiO2

The degradation of pharmaceutically active compounds (PhACs) under controlled and natural solar irradiation using immobilized TiO2 was studied in model solution and real urban wastewater effluents. The TiO2 coatings were prepared via the sol–gel method with two different configurations, using simple (thin films) and the “sandwich” approach. Prepared coatings were characterized employing X-ray diffraction (XRD), scanning electron microscopy (SEM), ellipsometry and UV–Vis diffuse reflectance spectroscopy. Decomposition of PhACs detected in urban wastewater effluents (diclofenac, carbamazepine, atenolol, propranolol, albuterol, ofloxacin, ciprofloxacin, azithromycin, erythromycin, hydrochlorothiazide, and furosemide) was monitored using Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry (UPLC-QqQ-MS/MS). Among detected PhACs three are included in the Watch List (EU Decision 2018/840). The “sandwich” coatings (deposited on frosted support) with the following structure: anatase layer, TiO2 P25 nanoparticles and anatase layer (sealing film) demonstrated the highest photocatalytic activity among all tested TiO2 coatings and were used for elimination of PhACs from real urban wastewater effluents. Photocatalytic treatment of urban wastewater effluents under controlled and natural solar irradiation led to moderate and high removal (>40%) of all detected PhACs except carbamazepine and atenolol, for which poor removal efficiency was observed (~20%). Some of the PhACs compounds present in wastewater effluents, such as diclofenac, ofloxacin, ciprofloxacin, hydrochlorothiazide and furosemide were sensitive to solar photolysis. The efficiency of solar photocatalytic inactivation of Escherichia coli present in urban wastewater effluent was similar to that of solar disinfection (SODIS).

On the Treatment Trains for Municipal Wastewater Reuse for Irrigation

Traditional urban wastewater treatment plants (UWTPs) are badly efficient in eliminating most contaminants of emerging concern (CECs), comprising antibiotics, antibiotic-resistant bacteria and antibiotic resistance genes (ARB & ARGs). Such pollutants induce some worry for nature and human health, especially if UWTPs effluents are reused for crop irrigation. In all probability, traditional UWTPs will need extra advanced treatment stages to satisfy water quality limits for wastewater reuse. Recently, Rizzo and his co-workers [1] published an excellent review that aims to suggest potential advanced treatment solutions, especially concerning the elimination of CECs and ARB & ARGs. They deeply assessed the performance of the best available technologies (BATs) for domestic wastewater treatment to decrease CECs and ARB & ARGs. Especially, they evaluated ozonation, activated carbon adsorption, chemical disinfection, UV radiation, advanced oxidation processes (AOPs) and membrane filtration focusing on their capacity to efficiently eliminate CECs and ARB & ARGs, as well as their benefits and disadvantages. This work focuses on likely treatment trains involving the aforesaid BATs. As concluded by Rizzo et al. [1] a one advanced treatment technique is not enough to reduce the liberation of chemical CECs and ARB & ARGs and make wastewater reuse for crop irrigation safer; however, an impertinent integration of them and an appropriate controlling program would be needed. There is no miraculous BAT for treating wastewater for water reuse in agriculture. An appropriate combination of many techniques would be suggested following each case.

Aquatic macroinvertebrates under stress: Bioaccumulation of emerging contaminants and metabolomics implications

The current knowledge on bioaccumulation of emerging contaminants (ECs) in aquatic invertebrates exposed to the realistic environmental concentrations is limited. Even less is known about the effects of chemical pollution exposure on the metabolome of aquatic invertebrates. We conducted an in situ translocation experiment with passive filter-feeding caddisfly larvae (Hydropsyche sp.) in an effluent-influenced river in order to i) unravel the bioaccumulation (and recovery) dynamics of ECs in aquatic invertebrates, and ii) test whether exposure to environmentally realistic concentrations of ECs will translate into metabolic profile changes in the insects. The experiment was carried out at two sites, upstream and downstream of the discharge of an urban wastewater treatment plant effluent. The translocated animals were collected at 2-week intervals for 46 days. Both pharmaceuticals and endocrine disrupting compounds (EDCs) were detected in water (62 and 7 compounds, respectively), whereas in Hydropsyche tissues 5 EDCs accumulated. Overall, specimens from the upstream site translocated to the impacted site reached higher ECs concentrations in their tissues, as a reflection of the contaminants’ water concentrations. However, bioaccumulation was a temporary process susceptible to change under lower contaminant concentrations. Non-targeted metabolite profiling detected fine metabolic changes in translocated Hydropsyche larvae. Both translocations equally induced stress, but it was higher in animals translocated to the impacted site.

HPLC-MS/MS multiclass determination of steroid hormones in environmental waters after preconcentration on the carbonaceous sorbent HA-C@silica

In this study, a sensitive and multiclass method has been developed for analysis of three families of steroid hormones, i.e. progestins, oestrogens, androgens, by SPE-HPLC-ESI-MS/MS. The extraction efficiency of thermally condensed humic acids onto silica sorbent (HA-C@silica), here for the first time studied for multiclass enrichment of these sex hormones, was tested in different environmental waters (tap and river water, urban wastewater treatment plant effluent) spiked at the nanograms per litre levels (5–1000 ng L−1). Quantitative adsorption was achieved using 200 mg sorbent for preconcentration of 250–1000 mL sample, at the native pH (pH = 6.5–7.7). Elution was performed by two sequential fractions (methanol followed by acetonitrile), obtaining in all the matrices investigated satisfactory recoveries (71% to 124% for river waters and 71–113% for urban wastewater treatment plant effluent) and RSDs below 15% (n = 3). The high enrichment factors (up to 4000) coupled with high-performance liquid chromatography tandem mass spectrometry quantification (MRM mode) provided low limits of detection and quantification (a few ng L−1), that are suitable for environmental monitoring. Most of the analytes were detected in river water and in wastewater effluent samples (in the ng L−1 concentration range), attesting their environmental diffusion. The proposed method was extended to a fourth class, Glucocorticoids, achieving good results in river samples, by the same SPE cartridge and chromatographic run.

Heterogeneous photocatalysis using UVA-LEDs for the removal of antibiotics and antibiotic resistant bacteria from urban wastewater treatment plant effluents

Heterogeneous photocatalysis using UVA-LEDs for the removal of antibiotics and antibiotic resistant bacteria from urban wastewater treatment plant effluents

Heterogeneous photocatalysis using UVA-LEDs for the removal of antibiotics and antibiotic resistant bacteria from urban wastewater treatment plant effluents

Secondary urban wastewater samples were spiked with azithromycin (AZT), trimethoprim (TMP), ofloxacin (OFL) and sulfamethoxazole (SMX) at 100 µg L−1 to investigate the efficiency of a TiO2-photocatalytic treatment using UVA-LEDs. Different operating parameters were studied, such as the irradiation conditions, catalyst load and the use of methanol as carrier solvent and radical scavenger. The most efficient conditions to treat spiked urban wastewater (4 LEDs symmetrically distributed and 1.00 g L−1 of catalyst) were also assessed on the removal of the antibiotics at real concentrations, as well as on the inactivation and regrowth of bacteria after 3-day storage (total and resistant heterotrophs, Escherichia coli and enterococci). Clindamycin (CLI) was targeted when SMX was not detected. One-hour treatment was enough to reduce the analysed antibiotics to values below the detection limits and to decrease the bacterial load by 2 log-units. Bacterial regrowth was observed for total heterotrophs, after the storage of photocatalytic treated wastewater, to values close to pre-treatment. However, the antibiotic resistance percentage of such stored wastewater was always similar or lower than that of secondary urban wastewater. Thus, the potential of this process as part of the tertiary treatment is demonstrated, but conditions must be adjusted to minimize microbial regrowth.

Survival of antibiotic resistant bacteria following artificial solar radiation of secondary wastewater effluent

Urban wastewater treatment plant effluents represent one of the major emission sources of antibiotic-resistant bacteria (ARB) in natural aquatic environments. In this study, the effect of artificial solar radiation on total culturable heterotrophic bacteria and ARB (including amoxicillin-resistant, ciprofloxacin-resistant, rifampicin-resistant, sulfamethoxazole-resistant, and tetracycline-resistant bacteria) present in secondary effluent was investigated. Artificial solar radiation was effective in inactivating the majority of environmental bacteria, however, the proportion of strains with ciprofloxacin-resistance and rifampicin-resistance increased in the surviving populations. Isolates of Pseudomonas putida, Serratia marcescens, and Stenotrophomonas maltophilia nosocomial pathogens were identified as resistant to solar radiation and to at least three antibiotics. Draft genome sequencing and typing revealed isolates carrying multiple resistance genes; where S. maltophilia (resistant to all studied antibiotics) sequence type was similar to strains isolated in blood infections. Results from this study confirm that solar radiation reduces total bacterial load in secondary effluent, but may indirectly increase the relative abundance of ARB.