Carbamazepine and diclofenac: removal in wastewater treatment plants and occurrence in water bodies

Electrochemical degradation of DCF by boron-doped diamond anode: degradation mechanism, pathways and influencing factors

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely detected in wastewater and surface water, indicating that the removal of NSAIDs by wastewater treatment plants was not efficient. Electrochemical advanced oxidation technology is considered to be an effective process. This study presents an investigation of the kinetics, mechanism, and influencing factors of diclofenac (DCF) degradation by an electrochemical process with boron-doped diamond anodes. Relative operating parameters and water quality parameters are examined. It appears that the degradation follows the pseudo-first-order degradation kinetics. DCF degradation was accelerated with the increase of pH from 6 to 10. The degradation was promoted by the addition of electrolyte concentrations and current density. Humic acid and bicarbonate significantly inhibited the degradation, whereas chloride accelerated it. According to the quenching tests, hydroxyl radicals (•OH) and sulfate radicals contributed 76.5% and 6.5%, respectively, to the degradation. Sodium sulfate remains a more effective electrolyte, compared to sodium nitrate and sodium phosphate, suggesting the quenching effect of nitrate and phosphate on •OH. Major DCF transformation products were identified. According to the degradation products detected by liquid chromatography-mass spectrometry, hydroxylation and decarboxylation are the main pathways of DCF degradation; while dechlorination, chlorination, and nitro substitution are also included in this electrochemical degradation process.

Fabrication of Bi4O5Br2 photocatalyst for carbamazepine degradation under visible-light irradiation

Bi₄O₅Br₂ with irregular flake shape was synthesized by a facile and energy-saving hydrolysis method. Its band gap energy (E_g) was 2.1 eV. The formation mechanism was proposed. The Bi₄O₅Br₂ exhibited superb visible-light-induced photocatalytic activity (>90%) toward the oxidation of carbamazepine. The kinetics rate constant (k) attained 0.0196 min^-1. The effect of Bi₄O₅Br₂ dosage, initial solution pH value, and inorganic anions on carbamazepine degradation was investigated. During the oxidation process, photogenerated holes (h⁺) and superoxide radical anions (•O₂^-) were the main active species. Based on the reaction intermediates results determined through a combined system of liquid chromatography and mass spectrometry, a possible reaction mechanism was speculated. The degree of contamination of carbamazepine solution after treatment was evaluated through the teratogenic effect experiment. After 120 min of visible light exposure, the carbamazepine solution is free of pollution. Also, the as-synthesized Bi₄O₅Br₂ maintains good chemical stability and could be reused in the photodegradation process, indicating its potential in practical applications.

Boosting pharmaceutical removal through aeration in constructed wetlands

This work evaluated the removal efficiency of 13 wastewater-borne pharmaceuticals in a pilot constructed wetland (CW) operated under different aeration strategies (no aeration, intermittent and continuous). Aeration improved the removal of conventional wastewater parameters and the targeted micropollutants, compared to the non-aerated treatment. Reduction of chemical oxygen demand (COD) and total nitrogen (TN) was slightly higher applying intermittent aeration than applying continuous aeration, the opposite was observed for the investigated pharmaceuticals. Seven targeted compounds were found in influent wastewater, and five of them (acetaminophen, diclofenac, ketoprofen, bezafibrate and gemfibrozil) were efficiently removed (> 83%) in the aerated systems. The overall risk of the investigated samples against aquatic ecosystems was moderate, decreasing in the order influent > no aeration > intermittent aeration > continuous aeration, based on the hazard quotient approach. Lorazepam, diclofenac and ketoprofen were the pharmaceuticals that could contribute the most to this potential environmental impact of the CW effluents after discharge. To the authors' knowledge this is the first sound study on the removal and fate of ketoprofen, bezafibrate, and lorazepam in aerated CWs, and provides additional evidence on the removal and fate of acetaminophen, diclofenac, gemfibrozil, and carbamazepine in this type of bioremediation systems at pilot plant scale.

Degradation of diclofenac sodium using Fenton-like technology based on nano-calcium peroxide

A nano-calcium peroxide (nCaO₂) powder with a purity of 89.1% was prepared using an improved traditional method. Then, the as-prepared nCaO₂ was used as the source of hydrogen peroxide (H₂O₂) for the Fenton-like degradation of diclofenac sodium (DCF). The results showed that nCaO₂ performed better for DCF removal when compared to nCaO₂ prepared by a conventional method and commercial calcium peroxide (CaO₂). Further experimental results indicated that 97.5% of DCF could be removed in 180 min at a nCaO₂/Fe²⁺-EDTA/DCF molar ratio of 16/8-8/1, which was more efficient than in the H₂O₂/EDTA-Fe²⁺/DCF and nCaO₂/Fe²⁺/DCF systems. The best removal rate of DCF was at pH 6.0, unlike previous claims that stated that the lower the pH in the buffer system, the better the degradation of DCF. In addition, the influence of water quality parameters, such as Cl^-, NO₃^-, SO₄^2-, HCO₃^-, and humic acid (HA), on DCF removal were evaluated. A free radical masking experiment revealed the existence of hydroxyl radical (OH), superoxide radical (O₂^-) and singlet oxygen (¹O₂), and indicated that the degradation of DCF was mainly due to oxidation caused by OH. Electron paramagnetic resonance (EPR) studies for different systems and different active oxygen species were carried out, and it was further confirmed that OH radicals have high intensity in the Fenton-like system based on nCaO₂. EPR results also showed that the addition of EDTA can promote the production of OH. According to the identification of the dominant reactive species and GC-MS, the possible theoretical DCF degradation pathways were proposed.

Spatial variation of pharmaceuticals in the unit processes of full-scale municipal wastewater treatment plants in Korea

Several reports have elucidated the removal of pharmaceutical residues in municipal wastewater treatment plants (WWTPs). However, there remains a need to determine the spatial distribution of pharmaceuticals in the unit processes of full-scale municipal WWTPs. Herein, spatial variations of fifteen pharmaceuticals in the unit processes of four full-scale municipal WWTPs were assessed by analyzing both solid and liquid samples. Furthermore, different pathways of each pharmaceutical such as biodegradation, adsorption, deconjugation, and electrostatic interaction were investigated. Pharmaceutical mass loading were measured at various points for the different unit process and evaluated using liquid chromatography-tandem mass spectrometry. The average mass loading of acetaminophen and caffeine decreased tremendously in the first biological treatment process regardless of the process configuration. In contrast, a temporary increase was observed in the mass loading of ibuprofen in the anaerobic and/or anoxic processes, which was presumably caused by deconjugation. Additionally, the adverse effect of coagulation on ibuprofen removal was validated. The major removal mechanism for the selected antibiotics, except for sulfamethoxazole, was the adsorption by biosolids due to electrostatic interaction. Subsequently, a drastic decrease was observed in their mass loadings in the solid-liquid separation process of the WWTPs. The membrane bioreactor (MBR) shows excellent capability for mitigation of pharmaceuticals in municipal wastewater because it comprises a high concentration of biosolids that act as adsorbents. The evaluation of the spatial variations of the selected pharmaceuticals in different unit processes provides valuable information on their behavior and removal mechanisms.

Occurrence of pharmaceutical residues, personal care products, lifestyle chemicals, illicit drugs and metabolites in wastewater and receiving surface waters of Krakow agglomeration in South Poland

This is the first study of broad range of chemical classes CECs conducted in the upper Wisla river catchment including the biggest WWTPs in this region and surface waters. The list of compounds is extensive and the paper provides, for the first time, better understanding of environmental burden from PCPCs in Poland. Cumulative contribution of hypertension pharmaceuticals, nonsteroidal anti-inflammatory drugs (NSAIDs) and lifestyle chemicals was 89% and 95% in wastewater influent, and 75% in wastewater effluent at both WWTPs. Significant removal efficiencies, exceeding 90%, were found for parabens, UV filters, NSAIDs, steroid estrogens, plasticizers, antibacterials/antibiotics, stimulants and metabolites and lifestyle chemicals. The comparison of the average mass loads of CECs between the influent and effluent, has shown that 27% and 29% of all detected CECs were removed by less than 50%. An increase of concentrations of CECs in the effluent was observed for 18% and 20% of all detected CECs in Kujawy and Plaszow WWTPs, respectively. Negative mass balances of fexofenadine, venlafaxine, o-desmethyltramadol, ketamine and temazepam were noted within WWTPs, which are a result of dissolution of persistent contaminants accumulated in aggregates and/or back-transformation or de-conjugation of metabolites into parent compounds. 44 CECs were detected in surface waters located upstream and downstream of the WWTPs. The concentrations of compounds were largely dependent on the dilution factor of WWTP discharge. The risk quotation (RQ) values for compounds present in surface waters were calculated in relation to their potential for bioaccumulation. Among compounds with high potential for bioaccumulation, with log K_OW ≥ 4.5, diclofenac, atorvastatin and triclosan were found to be of high risk. Many CECs with high, moderate or even low environmental impact have shown high potential for bioaccumulation and should be considered as priority at the same risk level. Moreover, possible synergistic action is still of concern.

Constructed wetlands operated as bioelectrochemical systems for the removal of organic micropollutants

The removal of organic micropollutants (OMPs) has been investigated in constructed wetlands (CWs) operated as bioelectrochemical systems (BES). The operation of CWs as BES (CW-BES), either in the form of microbial fuel cells (MFC) or microbial electrolysis cells (MEC), has only been investigated in recent years. The presented experiment used CW meso-scale systems applying a realistic horizontal flow regime and continuous feeding of real urban wastewater spiked with four OMPs (pharmaceuticals), namely carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBU) and naproxen (NPX). The study evaluated the removal efficiency of conventional CW systems (CW-control) as well as CW systems operated as closed-circuit MFCs (CW-MFCs) and MECs (CW-MECs). Although a few positive trends were identified for the CW-BES compared to the CW-control (higher average CBZ, DCF and NPX removal by 10-17% in CW-MEC and 5% in CW-MFC), these proved to be not statistically significantly different. Mesoscale experiments with real wastewater could thus not confirm earlier positive effects of CW-BES found under strictly controlled laboratory conditions with synthetic wastewaters.

Enzymatic activity changes in striped catfish Pseudoplatystoma magdaleniatum, induced by exposure to different concentrations of ibuprofen and triclosan

The present study aimed to evaluate the effects of exposure for four months, with ibuprofen and triclosan at 25 and 50 μg/L in Striped catfish Pseudoplatystoma magdaleniatum, evaluated between sexes and exposure times. Biochemical biomarkers such as lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, acetylcholinesterase, creatine kinase, lipid peroxidation, albumin, globulins, creatinine, and urea were evaluated. The results of this study suggest that both ibuprofen and triclosan at concentrations of 25 and 50 μg/L can cause alterations to P. magdaleniatum, interfering with the activity of certain enzymes associated with energy production, immune response, architecture, and cellular physiology. Also, we determined the current state of contamination in fish, the concentration of ibuprofen and triclosan in P. magdaleniatum muscle samples from the different places markets located on the banks of the main rivers of Colombia was quantified by UHPLC-QqQ-MS/MS, in three climatic periods; finding triclosan levels in the dry season in some of the sampling points compatible with enzyme-level alterations in this species.

A review of combined sewer overflows as a source of wastewater-derived emerging contaminants in the environment and their management

Emerging contaminants such as pharmaceuticals, illicit drugs and personal care products can be released to the environment in untreated wastewater/stormwater mixtures following storm events. The frequency and intensity of combined sewer overflows (CSOs) has increased in some areas due to increasing urbanisation and climate change. Therefore, this review provides an up-to-date overview on CSOs as an environmental source of emerging contaminants. Other than compounds with high removal, those chiral species subject to enantioselective changes (i.e. degradation or inversion) during wastewater treatment can be effective markers of CSO discharge in the environment. A proposed framework for the selection of emerging contaminants as markers of CSOs is outlined. Studies have demonstrated that CSOs can be the main source of emerging contaminants with high removal efficiency during wastewater treatment (e.g. > 90%). However, the impact of CSOs on the environment is location specific and requires decision-making on their appropriate management at catchment level. This process would be aided by further studies on CSOs which incorporate the monitoring of emerging contaminants and their effects in the environment with those more routinely monitored pollutants (e.g. pathogens and priority substances). Mitigation and treatment strategies for emerging contaminants in CSOs are also discussed.

Pharmaceutical and Personal Care Products in Different Matrices: Occurrence, Pathways, and Treatment Processes

The procedures for analyzing pharmaceuticals and personal care products (PPCPs) are typically tedious and expensive and thus, it is necessary to synthesize all available information from previously conducted research. An extensive collection of PPCP data from the published literature was compiled to determine the occurrence, pathways, and the effectiveness of current treatment technologies for the removal of PPCPs in water and wastewater. Approximately 90% of the compiled published papers originated from Asia, Europe, and the North American regions. The incomplete removal of PPCPs in different water and wastewater treatment processes was widely reported, thus resulting in the occurrence of PPCP compounds in various environmental compartments. Caffeine, carbamazepine, diclofenac, ibuprofen, triclosan, and triclocarban were among the most commonly reported compounds detected in water and solid matrices. Trace concentrations of PPCPs were also detected on plants and animal tissues, indicating the bioaccumulative properties of some PPCP compounds. A significant lack of studies regarding the presence of PPCPs in animal and plant samples was identified in the review. Furthermore, there were still knowledge gaps on the ecotoxicity, sub-lethal effects, and effective treatment processes for PPCPs. The knowledge gaps identified in this study can be used to devise a more effective research paradigm and guidelines for PPCP management.

Removal of Carbamazepine onto Modified Zeolitic Tuff in Different Water Matrices: Batch and Continuous Flow Experiments

Carbamazepine (CBZ) is the most frequently detected pharmaceutical residues in aquatic environments effluent by wastewater treatment plants. Batch and column experiments were conducted to evaluate the removal of CBZ from ultra-pure water and wastewater treatment plant (WWTP) effluent using raw zeolitic tuff (RZT) and surfactant modified zeolite (SMZ). Point zero net charge (pHpzc), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier Transform Infrared (FTIR) were investigated for adsorbents to evaluate the physiochemical changes resulted from the modification process using Hexadecyltrimethylammonium bromide (HDTMA-Br). XRD and FTIR showed that the surfactant modification of RZT has created an amorphous surface with new alkyl groups on the surface. The pHpzc was determined to be approximately 7.9 for RZT and SMZ. The results indicated that the CBZ uptake by SMZ is higher than RZT in all sorption tests (>8 fold). Batch results showed that the sorption capacity of RZT and SMZ in WWTP effluent (0.029 and 0.25 mg/g) is higher than RZT and SMZ (0.018 and 0.14 mg/g) in ultrapure water (1.6–1.8 fold). Batch tests showed that the equilibrium time of CBZ removal in the WWTP matrix (47 h) is much longer than CBZ removal in ultrapure water. The sorption capacity of RZT & SMZ in WWTP effluent (0.03, 0.33 mg/g) is higher than RZT and SMZ (0.02 and 0.17 mg/g) in ultrapure water (1.5–2 fold) using column test. This study has clearly demonstrated that the performance of RZT and SMZ is more efficient for the removal of CBZ from realistic wastewater than ultrapure water. It is evident that the surfactant modification of RZT has enhanced the CBZ removal in both matrices.

Matrix composition during ozonation of N-containing substances may influence the acute toxicity towards Daphnia magna

Micropollutants reach the aquatic environment through wastewater treatment plant effluents. Ozonation, applied in wastewater treatment for micropollutants abatement, can yield transformation products (TP), which might be of ecotoxicological concern. Previous studies on TP formation were mostly performed in ultrapure water. However, the water matrix can have a substantial influence and lead to unpredictable yields of TPs with toxicological potential. In this study the acute toxicity (immobilization) of the parent substances (isoproturon and metoprolol) and also of available TPs of isoproturon, metoprolol and diclofenac towards Daphnia magna (D. magna) were investigated. Further, the acute toxicity of TP mixtures, formed during ozonation of isoproturon, metoprolol and diclofenac was evaluated in the following systems: in the presence of radical scavengers (tert-butanol and dimethyl sulfoxide) and in the presence of hypobromous acid (HOBr), a secondary oxidant in ozonation. For all tested substances and TP standards, except 2,6-dichloroaniline (EC₅₀ 1.02 mg/L (48 h)), no immobilization of D. magna was detected. Ozonated pure water and wastewater did not show an immobilization effect either. After ozonation of diclofenac in the presence of dimethyl sulfoxide 95% (48 h) of the daphnids were immobile. Ozonation of parent substances, after the reaction with HOBr, showed no effect for isoproturon but a high effect on D. magna for diclofenac (95% immobilization (48 h)) and an even higher effect for metoprolol (100% immobilization (48 h)). These results emphasize that complex water matrices can influence the toxicity of TPs as shown in this study for D. magna.

Preparation and Characterization of Magnetic Polypyrrole Composite Microspheres Decorated with Copper (II) As A Sensing Platform for Electrochemical Detection of Carbamazepine

With a facile solvothermal technique, synthesis and application of Fe₃O₄@PPy–Cu^IIcomposite microspheres in the carbon ionic liquid matrix have been reported as highly sensitive sensors for voltammetric determination of Carbamazepine (CBZ). The morphology, crystal phase, and structure of synthesized nanocomposite were confirmed by routine methods, such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier translation infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Under the optimized conditions, differential pulse voltammetric (DPV) peak current was proportional to the CBZ concentration in the range of 0.05 to 25 μM with the detection limit (S/N = 3) of 32 nM. The storage stability of the modified electrode was also investigated which shows that the current responses remain about 95.2% of their initial values, indicating the appreciable storage stability of this sensor.The proposed electrode displayed excellent repeatability and it was satisfactorily used for determination of CBZ in real samples (urine, and serum samples) with high recovery.

Selective adsorption and enhanced photodegradation of diclofenac in water by molecularly imprinted TiO2

In the paper, molecularly imprinted TiO₂ was prepared by surface molecularly imprinted technology and liquid phase deposition method for preferential removal of persistent toxic pollutants from complex environmental water. Diclofenac was selected as the template molecule and target for photodegradation study. The characterization results of SEM, TEM, FTIR and XRD showed that the TiO₂ film with imprinted diclofenac was successfully synthesized on the surface of TiO₂ particles. Meanwhile, the adsorption and photodegradation experiments also indicated that the molecularly imprinted TiO₂ had larger adsorption capacity, better selectivity and higher photodegradation performance for diclofenac than non-imprinted TiO₂. The primary active species and degradation pathways during photodegradation process were also elucidated according to radical capture experiments and UPLC-MS-TOF technology. The prepared molecularly imprinted TiO₂ has the advantages of efficient removal ability, high stability and environmental protection, so it has a wide application value in water treatment and water environmental restoration, especially when involved persistent toxic pollutants.

In situ functionalization of a cellulosic-based activated carbon with magnetic iron oxides for the removal of carbamazepine from wastewater

The main goal of this work was to produce an easily recoverable waste-based magnetic activated carbon (MAC) for an efficient removal of the antiepileptic pharmaceutical carbamazepine (CBZ) from wastewater. For this purpose, the synthesis procedure was optimized and a material (MAC4) providing immediate recuperation from solution, remarkable adsorptive performance and relevant properties (specific surface area of 551 m² g^-1 and saturation magnetization of 39.84 emu g^-1) was selected for further CBZ kinetic and equilibrium adsorption studies. MAC4 presented fast CBZ adsorption rates and short equilibrium times (< 30-45 min) in both ultrapure water and wastewater. Equilibrium studies showed that MAC4 attained maximum adsorption capacities (q_m) of 68 ± 4 mg g^-1 in ultrapure water and 60 ± 3 mg g^-1 in wastewater, suggesting no significant interference of the aqueous matrix in the adsorption process. Overall, this work provides evidence of potential application of a waste-based MAC in the tertiary treatment of wastewaters. Graphical abstract.

Carbamazepine removal from low-strength municipal wastewater using a combined UASB-MBR treatment system

An Upflow Anaerobic Sludge Blanket reactor combined with a two-stage membrane bioreactor were operated for 193 days in order to evaluate the biological removal of carbamazepine (CBZ) from low-strength municipal wastewater. The system worked in three different organic load stages (0.7 ± 0.1 kg COD·m^-3·d^-1, 0.4 ± 0.1 kg COD·m^-3·d^-1 and 0.1 ± 0.0 kg COD·m^-3·d^-1) to assess the impact of the influent OLR on operational parameters such as anaerobic and aerobic sludge retention time (SRT), acidity, volatile fatty acids (VFAs), biomass activity or biogas production. The highest carbamazepine removals were achieved during the anaerobic stage (UASB reactor), reaching averages of 48.9%, 48.0% and 38.2% operating at high, medium and low OLR, respectively. The aerobic treatment (MBR) served as post-treatment, improving the removals, and the global UASB-MBR system reached averages of 70.0%, 59.6% and 49.8% when the influent was at medium and low OLR, respectively. The results demonstrate the potential of combined biological systems on the removal of recalcitrant pharmaceuticals.

Immunity and inflammatory responses in gilthead sea bream (Sparus aurata L.) exposed to sub-lethal mixture of carbamazepine, cadmium chloride and polybrominated diphenyl ether

Chemical contaminants such as industrial and urban by-products, pharmaceuticals, drugs metabolites and, plastics, are continuously found in the oceans, affecting its quality and organism's welfare. Although these compounds are found at concentrations ranged ng L^-1, there is an increasing concern about the potential adverse effects of the interactions among those substances present, simultaneously, in a mixture. In the present study, specimens of sea bream (Sparus aurata) were exposed, by food, to rising concentrations of a mixture of carbamazepine, polybrominated diphenyl ether-47 and cadmium chloride, for 15 days and then, maintained, with the same control diet, without contaminants, for other 15 days. Samples of skin mucus, serum, head-kidney, liver and intestine were sampled at 0, 15 and 30 days. Cellular immune parameters were evaluated on head-kidney, as well as humoral parameters were determined on skin mucus and serum. In addition, the expression of some genes, related to immunity, was analysed on liver and intestine. Both cellular and humoral response were affected at 15 days, showing slightly signs of recovery at 30 days. Besides, the expression of immune-related genes was highly affected, suggesting the development of inflammatory processes, as well as a reduction of immune parameters. Overall, the mixture of compounds severally affected the immune system of sea bream, suggesting a lower degree of recovery. The prolonged exposure to a mixture of these compounds could entail serious change on population immunity and, eventually, promote changes on marine biota.

Photocatalytic degradation of diclofenac using TiO2-CdS heterojunction catalysts under visible light irradiation

The present study reports the photocatalytic degradation of analgesic drug diclofenac using the hydrothermally prepared TiO₂-CdS heterojunction catalyst. The results suggest that the prepared catalysts exhibited excellent photocatalytic activity under visible light irradiation. The photodegradation kinetics were well fitted to the pseudo-first-order reaction. The apparent reaction rate constant for TC5 catalyst in the diclofenac degradation was 0.02316 min^-1. Mineralisation of diclofenac using TC5 photocatalyst was around 86% within 4 h of irradiation time. The operating parameters such as optimal catalyst dosage, apparent solution pH and the effect of initial diclofenac concentration were also studied using the TC5 catalyst. The role of active species in the degradation mechanism was elucidated and it was found that the hydroxyl radical is the main active species in the diclofenac degradation mechanism. The charge transfer between heterojunction catalysts is facilitated by direct Z-scheme heterojunction structure. The coupled photocatalysts also showed good photochemical stability and reusability over five successive reaction cycles. The tentative degradation pathway has been devised based on LC-MS peaks, and it is found that only m/z 224, m/z 178 and m/z 124 were persisted at the end of the reaction.

Removal of pharmaceuticals and personal care products using native fungal enzymes extracted during the ligninolytic process

Significant concentrations of pharmaceuticals and personal care products (PPCPs) have been detected in aquatic environment. Fungal enzymatic processes can oxidize these persistent PPCPs; thus, these processes have attracted considerable attention from the scientific community. Here, we evaluated the efficacy of the removal of PPCPs using native fungal enzymes derived from Bjerkandera spp. TBB-03 under various conditions. Among the eight lignocellulosic substrates, ash, which showed the highest laccase production, was selected as the sole enzyme inducer. TBB-03 laccase was found to exhibit remarkable stability under varied pH and temperature conditions. Acetaminophen and bisphenol A were effectively removed by TBB-03 laccase under various conditions, except at pH 8. Although TBB-03 laccase could not efficiently remove single-state sulfamethoxazole directly, a 22% of improvement in sulfamethoxazole removal was observed in the presence of acetaminophen. Overall, our proposed approach showed that Bjerkandera adusta TBB-03 can be potentially applied for further research regarding PPCP remediation.

The impact of chloride and chlorine radical on nitrite formation during vacuum UV photolysis of water

The impact of chloride ion and chlorine radical on the formation of nitrite was investigated under Vacuum-UV (VUV) photolysis of nitrate contaminating water. An increase in chloride concentration reduced nitrite formation in part due to the relatively high VUV absorption of chloride. The use of various radical scavengers, such as acetate and acetone, helped delineate the specific roles of hydroxyl radical (HO) and chlorine radical (Cl) in oxidation and VUV photolysis of nitrate, and the subsequent formation of nitrite. HO reduced nitrite formation due to its high reaction rate constant with nitrite. Nitrite formation in both chloride and dissolved organic carbon (DOC) containing solution depended primarily on their relative concentrations. Carbamazepine (CBZ) was also used to analyze the effect of Cl on both the degradation of CBZ and the formation of nitrite. Cl showed to significantly increase the degradation of CBZ, but it had little impact on the formation of nitrite. This paper, utilizing detailed experimental data combined with kinetic modeling and mechanistic analysis of VUV photolysis in the presence of chloride and nitrate, provides the necessary scientific guidance towards more effective and optimized applications of VUV technology for drinking water treatment.

On the Use of Mechanistic Soil-Plant Uptake Models: A Comprehensive Experimental and Numerical Analysis on the Translocation of Carbamazepine in Green Pea Plants

Food contamination is a major worldwide risk for human health. Dynamic plant uptake of pollutants from contaminated environments is the preferred pathway into the human and animal food chain. Mechanistic models represent a fundamental tool for risk assessment and the development of mitigation strategies. However, difficulty in obtaining comprehensive observations in the soil-plant continuum hinders their calibration, undermining their generalizability and raising doubts about their widespread applicability. To address these issues, a Bayesian probabilistic framework is used, for the first time, to calibrate and assess the predictive uncertainty of a mechanistic soil-plant model against comprehensive observations from an experiment on the translocation of carbamazepine in green pea plants. Results demonstrate that the model can reproduce the dynamics of water flow and solute reactive transport in the soil-plant domain accurately and with limited uncertainty. The role of different physicochemical processes in bioaccumulation of carbamazepine in fruits is investigated through Global Sensitivity Analysis, which shows how soil hydraulic properties and soil solute sorption regulate transpiration streams and bioavailability of carbamazepine. Overall, the analysis demonstrates the usefulness of mechanistic models and proposes a comprehensive numerical framework for their assessment and use.

Removal and environmental risk assessment of contaminants of emerging concern from irrigation waters in a semi-closed microalgae photobioreactor

The present study evaluated the efficiency of a semi-closed, tubular, horizontal photobioreactor (PBR) to treat a mixture of irrigation and rural drainage water, focusing in the removal of different contaminants of emerging concern (CECs), and evaluating the environmental impact of the resulting effluent. Target CECs included pharmaceuticals, personal care products and flame retardants. Of the 13 compounds evaluated, 11 were detected in the feed water entering the PBR, and diclofenac (DCF) (1107 ng L^-1) and N,N-diethyl-toluamide (DEET) (699 ng L^-1) were those present at the greatest concentrations. The best removal efficiencies were achieved for the pharmaceuticals diazepam (94%), lorazepam (LZP) (83%) and oxazepam (OXA) (71%), and also for ibuprofen (IBU) (70%). For the rest of the CECs evaluated, attenuation was similar to that obtained after conventional wastewater treatment, ranging from basically no elimination (carbamazepine (CBZ) and tris-(2-chloroethyl) phosphate (TCEP)) to medium efficiencies (DCF and tributyl phosphate (TBP) (50%)). Environmental risk assessment based on hazard quotients (HQs) resulted in HQ values < 0.1 (no risk associated) for most of the compounds and most of the trophic levels considered. Values between 1 and 10 (moderate risk) were obtained for tonalide (AHTN) (fish) and CBZ (invertebrates). The most sensitive trophic level was green algae, whereas fish and aquatic plants were the most resilient. Our results suggest that microalgae-based treatments could become a green, cost-effective alternative to conventional wastewater treatment regarding the efficient elimination of these contaminants.

In situ construction of Z-scheme FeS2/Fe2O3 photocatalyst via structural transformation of pyrite for photocatalytic degradation of carbamazepine and the synergistic reduction of Cr(VI)

Pyrite is the most abundant sulfide semiconductor mineral with excellent optical properties. However, few reports have investigated its photocatalytic activity because of the low photogenerated carrier separation efficiency. In this work, a Z-scheme FeS₂/Fe₂O₃ composite photocatalyst was fabricated in situ via structural transformation of pyrite through heat treatment. A remarkably enhanced photocatalytic performance was observed over the FeS₂/Fe₂O₃ composite photocatalyst. Compared with the pristine pyrite, the degradation efficiency of carbamazepine (CBZ) reached 65% at the added hexavalent chromium (Cr(Ⅵ)) concentration of 20 mg/L and the Cr(Ⅵ) was nearly completely reduced in the mixed system using FeS₂/Fe₂O₃ within 30 min under simulated solar light irradiation. The enhanced photocatalytic activity can be attributed to the efficient separation and transfer of photogenerated carriers in the FeS₂/Fe₂O₃ composite photocatalyst. This facilitated the generation of •OH, hole (h⁺) and •O₂^- species, which participated in the photocatalytic reaction with CBZ. Based on the measurement of the active species and electric properties, a Z-scheme electron transfer pathway was proposed for the FeS₂/Fe₂O₃ composite photocatalyst. This work broadens the application potential of pyrite in environmental remediation.

Enhancing the degradation of carbamazepine by UVA-LED/WO3 process with peroxydisulfate: Effects of light wavelength and water matrix

In this study, peroxydisulfate (PDS) was used as electron acceptor to improve the photocatalytic activity of WO₃. The results indicated that the degradation of carbamazepine by UVA-LED/WO₃/PDS process followed pseudo-first order and PDS addition significantly enhanced the degradation rate by inhibiting the recombination of electrons and holes. The observed pseudo-first order rate constant (k_obs) was in linear relationship with the dosage of WO₃, while inversely proportional to the initial concentration of CBZ. PDS decreased the k_obs slightly when its concentration exceeded 0.5 mM. The 365 nm UVA-LED performed much better than 385 nm or 405 nm even though its energy efficiency was the lowest. Based on the steady-state kinetic model, sulfate radical was the dominant radical. The effects of water matrix were complex: bicarbonate ion and humic acid showed strong inhibitory effect; increasing the pH above 7 led to significant drop in CBZ removal; sulfate ion slightly decreased the k_obs while 5 mM chloride ion more than doubled the k_obs. The interactions between anions and WO₃ surface were theoretically analysed to explain the effects of anions. The electrical energy per order values suggest that UVA-LED/WO₃/PDS process is suitable for water with low organic carbon.

Rapid determination of pharmaceuticals in wastewater by direct infusion HRMS using target and suspect screening analysis

A wide-scope screening of active pharmaceutical ingredients (APIs) and their transformation products (TPs) in wastewater can yield valuable insights and pinpoint emerging contaminants that have not been previously reported. Such information is relevant to investigate their occurrence and fate in various environmental compartments. In this study, we explored the applicability of direct infusion high resolution mass spectrometry (DI-HRMS) for comprehensive and rapid detection of APIs and their TPs in wastewater samples. The method was developed using a Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) system and incorporated both wide-scope suspect screening and semi-quantitative determination of selected analytes. The identification strategy was based on the following criteria: narrow accurate mass window (±1.25 ppm) for two most abundant full-MS signals, isotopic pattern fit and additional confirmation on the basis of MS² spectra at three fragmentation levels. The tentative identification of suspects and target compounds relied on an in-house database containing more than 500 different APIs and TPs. The measured fragment spectra were matched against experimental MS² patterns obtained from a publicly available spectral library (MassBank of North America) and in-silico generated fragmentation features (from the CFM-ID algorithm). In total, 79 suspects were identified and 24 target compounds were semi-quantified in 72 wastewater samples. The highest detection frequencies in treated wastewater effluents were observed for diclofenac, metoprolol and telmisartan, while hydroxydiclofenac, dextrorphan, and carbamazepine metabolites were the most frequently detected TPs. The obtained API profiles were in accordance with the national consumption statistics and the origin of wastewater samples. The developed method is suitable for rapid screening of APIs in wastewater and can be used as a complementary tool to characterize API emissions from wastewater treatment facilities and to identify problematic compounds that require more rigorous monitoring.

Occurrence and fate of pharmaceuticals in a wastewater treatment plant from southeast of Spain and risk assessment

Pharmaceutical and personal care products (PPCPs) can be incorporated into ecosystems and pose potential environmental and health hazards. These pollutants are becoming omnipresent in the environment because they are introduced by several sources, being particularly important the contribution of human-derived pharmaceuticals. The presence of PPCPs in waters has received increasing attention in recent years, resulting in great concern regarding their occurrence, transformation, fate and environmental risk. For that reason, the pharmaceuticals carbamazepine (CBZ), diclofenac (DIC), ibuprofen (IBU), ketoprofen (KET) and naproxen (NPX) were measured in the waters and sludge of several parts of a double step activated sludge wastewater treatment plant (WWTP) from Murcia (Spain). With these results, the biological degradation constant, the sorption coefficient and the pharmaceutical removal were calculated. Possible risks to humans and ecosystems were also evaluated. These showed good degradation of IBU and NPX (74.4 and 84.9%, respectively), while CBZ didn't display any degradation. DIC was the compound most likely to be sorbed into the sludge (3.09 L kg^-1). The PPCPs removal in this double stage WWTP was compared to a previous data obtained in a WWTP of the same region with an activated sludge (single biological batch reactor). The results showed a decrease in the removal of the double stage plant, probably due to the lower hydraulic retention time employed. The study of the human and ecological risk quotients indicates a low risk of the selected pharmaceuticals (RQ < 0.1).

Environmentally relevant concentrations of carbamazepine induced lipid metabolism disorder of Chinese rare minnow (Gobiocypris rarus) in a gender-specific pattern

Carbamazepine (CBZ), an anticonvulsant and mood stabilizer, is ubiquitous distributed in aquatic environment. Though the toxicity and endocrine disrupting effect of CBZ on non-target organisms have been studied, its lipotoxity are scarcely known. To assess the lipotoxicity of CBZ, 2-month-old Chinese rare minnow were exposed to 0, 1, 10, and 100 μg/L CBZ for 90 d. Obvious dyslipidemia was observed after 30 d and 90 d exposure, whereas overt hyperlipidemia was observed in males at 100 μg/L treatments. Severe lipid droplet accumulation in livers was observed at 10 and 100 μg/L treatments for 30 d and in females, whereas those was observed at all treatments in males. In addition, serious mitochondria damage was observed in males at 100 μg/L treatments. After 90 d exposure, the enzyme activities of FAS and ACCα were significantly increased at 10 and 100 μg/L treatments, whereas HMGCR were markedly increased at 100 μg/L treatments (p < 0.05). However, ACCβ were markedly decreased in females at 10 and 100 μg/L treatments and in males at all treatments (p < 0.05). The transcription levels of fasn, accα, hmgcrα, fdft1, idi1, plin1, plin2, caveolin1, and caveolin2 were significantly increased at 100 μg/L treatments (p < 0.05). Moreover, the body weight was obviously increased at 10 and 100 μg/L treatments in males (p < 0.05). Our results confirmed that environmental relevant concentrations CBZ induced lipid metabolism disorder and mitochondria damage of Chinese rare minnow in a gender-specific pattern, which provided a new insight into the lipotoxicity mechanism of CBZ.

Multicompartment and cross-species monitoring of contaminants of emerging concern in an estuarine habitat

The fate of many chemicals in the environment, particularly contaminants of emerging concern (CEC), have been characterised to a limited extent with a major focus on occurrence in water. This study presents the characterisation, distribution and fate of multiple chemicals including pharmaceuticals, recreational drugs and pesticides in surface water, sediment and fauna representing different food web endpoints in a typical UK estuary (River Colne, Essex, UK). A comparison of contaminant occurrence across different benthic macroinvertebrates was made at three sites and included two amphipods (Gammarus pulex &Crangon crangon), a polychaete worm (Hediste diversicolor) and a gastropod (Peringia ulvae). Overall, multiple contaminants were determined in all compartments and ranged from; Collapse

Key Words

• Environmental risk
• Invertebrate
• Occurrence
• Pesticides
• Pharmaceuticals
• Sediment

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MESH Headings

• Animals
• Ecosystem
• Environmental Monitoring
• Pesticides/analysis
• Rivers
• Water Pollutants, Chemical/analysis

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Grants

• MR/S019669/1 Medical Research Council

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Affiliation(s)

Thomas H Miller Department of Life Sciences, College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, UB8 3PH, UK; Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK.
Keng Tiong Ng Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK; Environmental Research Group, School of Public Health, Faculty of Medicine, Imperial College London, UK
Aaron Lamphiere School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO43SQ, UK
Tom C Cameron School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO43SQ, UK
Nicolas R Bury School of Science, Technology and Engineering, University of Suffolk, James Hehir Building, University Avenue, Ipswich, Suffolk, IP3 0FS, UK; Suffolk Sustainability, University of Suffolk, Waterfront Building, Neptune Quay, Ipswich, IP4 1QJUK, UK
Leon P Barron Department of Analytical, Environmental & Forensic Sciences, School of Population Health & Environmental Sciences, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London, SE1 9NH, UK; Environmental Research Group, School of Public Health, Faculty of Medicine, Imperial College London, UK

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Carbamazepine at environmentally relevant concentrations caused DNA damage and apoptosis in the liver of Chinese rare minnows (Gobiocypris rarus) by the Ras/Raf/ERK/p53 signaling pathway

To assess genetoxicity and the underlying mechanisms of carbamazepine (CBZ) toxicity in fish, adult Chinese rare minnows (Gobiocypris rarus) were exposed to 1, 10, and 100 μg/L CBZ for 28 d. Comet assays indicated that hepatic DNA damage was significantly increased in groups of minnows exposed to CBZ at all concentrations in a dose-dependent manner compared to those of the control groups (p < 0.05). Liver levels of 8-hydroxydeoxyguanosine (8-OHdG) were significantly increased at 10 and 100 μg/L CBZ (p < 0.05). TUNEL assays indicated that the average apoptotic rates of the livers of female and male minnows were significantly increased following exposure to CBZ at all concentrations for 28 d (p < 0.05). Significant increases in caspase 3 and 9 activities after CBZ exposure at all concentrations and caspase 8 at 10 and 100 μg/L CBZ exposure reflected the presence of mitochondrial apoptosis (p < 0.05). The mRNA levels of gadd45a, mdm2, casp3 and casp9 in female and male minnows exposed to CBZ at all concentrations were significantly increased compared with those in the control groups (p < 0.05). Significant increases in the levels of p21 in female minnows exposed to 1 and 100 μg/L CBZ, p53 in female minnows at all CBZ treatments and bcl2 in male minnows exposed to 1 and 100 μg/L CBZ were observed, indicating p53 pathway activation. The inhibition of ras levels in females and males exposed to CBZ at all concentrations and increased levels of raf1 in males exposed to CBZ at all concentrations indicated Ras/Raf1/MAPK (ERK) activation. Therefore, the present study demonstrates that CBZ at environmentally relevant levels induces DNA damage and apoptosis in Chinese rare minnows by the Ras/Raf/ERK/p53 signaling pathway.

Presence and Reduction of Anthropogenic Substances with UV Light and Oxidizing Disinfectants in Wastewater—A Case Study at Kuopio, Finland

Anthropogenic substances are a major concern due to their potential harmful effects towards aquatic ecosystems. Because wastewater treatment plants (WWTPs) are not designed to remove these substances from wastewater, a part of the anthropogenic substances enter nature via WWTP discharges. During the spring 2019, the occurrence of anthropogenic substances in the municipal wastewater effluent in Kuopio, Finland, was analysed. Furthermore, the capacity of selected disinfection methods to reduce these substances from wastewater was tested. The disinfection methods were ozonation (760 mL min−1) with an OxTube hermetic dissolution method (1), the combined usage of peracetic acid (PAA) (<5 mg L−1) and ultraviolet (UV) disinfection (12 mJ/cm2) (2), and the combined usage of hydrogen peroxide (H2O2) (<10 mg L−1) and UV disinfection (12 mJ/cm2) (3). The substances found at the concentrations over 1 µg L−1 in effluent (N = 3) were cetirizine (5.2 ± 1.3 µg L−1), benzotriazole (BZT) (2.1 ± 0.98 µg L−1), hydrochlorothiazide (1.7 ± 0.2 µg L−1), furosemide (1.6 ± 0.2 µg L−1), lamotrigine (1.5 ± 0.06 µg L−1), diclofenac (DCF) (1.4 ± 0.2 µg L−1), venlafaxine (1.0 ± 0.13 µg L−1) and losartan (0.9 ± 0.2 µg L−1). The reduction (%) with different methods (1, 2, 3) were: cetirizine (99.9, 5.0, NR = no removal), benzotriazole (67.9, NR, NR), hydrochlorothiazide (91.1, 5.9, NR), furosemide (99.7, 5.9, NR), lamotrigine (46.4, NR, 6.7), diclofenac (99.7, 7.1, 16.7), venlafaxine (91.3, NR, 1.1), losartan (99.6, 13.8, NR). Further research concerning the tested disinfection methods is needed in order to fully elucidate their potential for removing anthropogenic substances from purified wastewater.

Influence of Diclofenac on Activated Sludge Bacterial Communities in Fed-Batch Reactors

Research background

The occurrence and environmental toxicity of pharmaceuticals have recently attracted increasing attention. Diclofenac is a highly consumed non-steroidal anti-inflammatory drug, which is often detected in wastewaters, but investigations of its influence on bacteria are scarce.

Experimental approach

We investigated the influence of this pharmaceutical on bacterial community in activated sludge exposed to increasing concentrations of diclofenac in fed-batch reactors over 41 days. Nitrification activity of the activated sludge was measured and changes in bacterial community structure were followed using culture-independent molecular method (terminal restriction fragment length polymorphism, T-RFLP) and by the cultivation approach.

Results and conclusions

Nitrification activity was not detectably influenced by the addition of diclofenac, while the main change of the bacterial community structure was detected only at the end of incubation (after 41 days) when diclofenac was added to artificial wastewater as the only carbon source. Changes in community composition due to enrichment were observed using cultivation approach. However, taxonomic affiliation of isolates did not match taxons identified by T-RFLP community profiling. Isolates obtained from activated sludge used as inoculum belonged to five genera: Comamonas, Arthrobacter, Acinetobacter, Citrobacter and Aeromonas, known for their potential to degrade aromatic compounds. However, only Pseudomonas species were isolated after the last enrichment step on minimal agar plates with diclofenac added as the sole carbon source.

Novelty and scientific contribution

Our results suggest that the selected recalcitrant and commonly detected pharmaceutical does not strongly influence the sensitive and important nitrification process of wastewater treatment. Moreover, the isolated strains obtained after enrichment procedure that were able to grow on minimal agar plates with diclofenac added as the only carbon source could serve as potential model bacteria to study bacterial diclofenac degradation.

Algal softening followed by ozonation: The fate of persistent micropollutants and natural organic matter in groundwater

A proof-of-concept study evaluates the performance of a novel strategy using photosynthetic microorganisms to soften groundwater instead of using caustic chemicals. The microalga Scenedesmus quadricauda was used to increase the pH of the groundwater via natural photosynthesis. This work applied softening as a pretreatment to ozonation of hard groundwater and mainly focused on investigating the multiple effects of algal softening on the degradation of persistent micropollutants upon subsequent ozonation. The algae-induced alkaline conditions (pH > 10) were favorable to catalyze the formation of OH radicals directly from O₃ molecules. Moreover, algal softening removed the strong radical-scavenging carbonate species (HCO₃^- and CO₃^2-) to a much greater extent than that achieved by chemical softening, which was attributed to the combination of mineral carbonation and metabolic CO₂ reduction. The fate of the natural organic matter (NOM) was characterized with spectroscopy, chromatography, and bioassay, which indicates that algal treatment decomposed the NOM to be less susceptible to attack by OH radicals. Consequently, the ozonation of alkaline groundwater achieved a better removal of the micropollutant residues in groundwater. Carbamazepine and diclofenac were used as model chemicals of persistent groundwater contaminants and were almost completely removed with an addition of 1.25 mg O₃ L^-1 (0.63 mg-O₃ mg-C^-1).

Does diclofenac act like a photosynthetic herbicide on green algae? Chlamydomonas reinhardtii synchronous culture-based study with atrazine as reference

The non-steroidal anti-inflammatory drug diclofenac (DCF) is one of the commonly used and frequently detected drugs in water bodies, and several studies indicate its toxic effect on plants and algae. Studies performed with asynchronous Chlamydomonas reinhardtii cultures indicated that DCF inhibit the growth of population of the algae. Here, a synchronous population of C. reinhardtii, in which all cells are in the same developmental phase, is used. Following changes in cells size, photosynthetic activity and gene expression, we could compare, at the level of single cell, DCF-mediated effects with the effects caused by atrazine, a triazine herbicide that inhibits photosynthesis and triggers oxidative stress. Application of DCF and atrazine at the beginning of the cell cycle allowed us to follow the changes occurring in the cells in the subsequent stages of their development. Synchronized Chlamydomonas reinhardtii cultures (strain CC-1690, wild type) were exposed to diclofenac sodium salt (135 mg/L) or atrazine (77.6 µg/L). The cell suspension was sampled hourly (0-10 h) in the light period of the cell cycle to determine cell number and volume, photosynthetic pigment content, chlorophyll a fluorescence (OJIP test) in vivo, and selected gene expression (real-time qPCR), namely psbA, psaA, FSD1, MSD3 and APX1. The two toxicants differently influenced C. reinhardtii cells. Both substances decreased photosynthetic "vitality" (PI - performance index) of the cells, albeit for different reasons. While atrazine significantly disrupted the photosynthetic electron transport, resulting in excessive production of reactive oxygen species (ROS) and limited cell growth, DCF caused silencing of photosystem II (PSII) reaction centers, transforming them into "heat sinks", thus preventing significant ROS overproduction. Oxidative stress caused by atrazine was the probable reason for the rapid appearance of phytotoxic action soon after entering the cells, while the effects of DCF could only be seen several hours after treatment. A comparison of DCF-caused effects with the effects caused by atrazine led us to conclude that, although DCF cannot be regarded as typical photosynthetic herbicide, it exhibits an algicidal activity and can be potentially dangerous for aquatic plants and algae.

Heterogeneous Electro-Fenton as “Green” Technology for Pharmaceutical Removal: A Review

The presence of pharmaceutical products in the water cycle may cause harmful effects such as morphological, metabolic and sex alterations in aquatic organisms and the selection/development of organisms resistant to antimicrobial agents. The compounds’ stability and persistent character hinder their elimination by conventional physico-chemical and biological treatments and thus, the development of new water purification technologies has drawn great attention from academic and industrial researchers. Recently, the electro-Fenton process has been demonstrated to be a viable alternative for the removal of these hazardous, recalcitrant compounds. This process occurs under the action of a suitable catalyst, with the majority of current scientific research focused on heterogeneous systems. A significant area of research centres working on the development of an appropriate catalyst able to overcome the operating limitations associated with the homogeneous process is concerned with the short service life and difficulty in the separation/recovery of the catalyst from polluted water. This review highlights a present trend in the use of different materials as electro-Fenton catalysts for pharmaceutical compound removal from aquatic environments. The main challenges facing these technologies revolve around the enhancement of performance, stability for long-term use, life-cycle analysis considerations and cost-effectiveness. Although treatment efficiency has improved significantly, ongoing research efforts need to deliver economic viability at a larger scale due to the high operating costs, primarily related to energy consumption.

Fate of Emerging Contaminants in High-Rate Activated Sludge Systems

High-rate activated sludge (HRAS) systems are designed to shift the energy-intensive processes to energy-saving and sustainable technologies for wastewater treatment. The high food-to-microorganism (F/M) ratios and low solid retention times (SRTs) and hydraulic retention times (HRTs) applied in HRAS systems result in the maximization of organic matter diversion to the sludge which can produce large amounts of biogas during anaerobic digestion, thus moving toward energy-neutral (or positive) treatment processes. However, in addition to the energy optimization, the removal of emerging contaminants (ECs) is the new challenge in wastewater treatment. In the context of this study, the removal efficiencies and the fates of selected ECs (three endocrine disruptors (endocrine disrupting chemicals (EDCs))—nonylphenol, bisphenol A and triclosan, and four pharmaceuticals (PhACs)—ibuprofen, naproxen, diclofenac and ketoprofen) in HRAS systems have been studied. According to the results, EDCs occurred in raw wastewater and secondary sludge at higher concentrations compared to PhACs. In HRAS operating schemes, all compounds were poorly (<40%) to moderately (<60%) removed. Regarding removal mechanisms, biotransformation was found to be the dominant process for PhACs, while for EDCs sorption onto sludge is the most significant removal mechanism affecting their fates and their presence in excess sludge.

Dual radicals-enhanced wet chemical oxidation of non-biodegradable chemicals

Total organic carbon (TOC) has been suggested and utilized as an index of organic matter in aqueous phases. The overall performance of TOC is highly dependent on the method of oxidation of organic matter to carbon dioxide, such as high-temperature combustion (HTC) and wet chemical oxidation (WCO). HTC requires more energy and maintenance cost, it is a major barrier to the field application. In contrast, WCO is more suitable for the application of on-line monitoring systems due to requiring lower energy and easy maintenance. However, WCO shows lower oxidation than HTC, thus, oxidation performance should be improved for the application to the field. In this study, a dual radical system (DRS), including sulfate and hydroxyl radicals, was proposed to enhance oxidation ability. The DRS uses alkaline pH and persulfate to generate sulfate radicals, which have been used to activate hydroxyl radicals and oxidize organic matter. The oxidation mechanism for the DRS has been verified using model chemicals with different reaction rate constants. The applicability of the DRS has been confirmed using authentic wastewater with a high concentration of chloride. In this study, the DRS showed similar performance compared to the HTC within 10 % error range. The DRS shows similar oxidation performance with HTC even at a high concentration of chloride. DRS did not show interference by the presence of chloride up to 30,000 mg/L of chloride. Results of this study indicate that the DRS can enhance overall oxidation performance compared to the conventional WCO system.

Efficient photocatalytic destruction of recalcitrant micropollutants using graphitic carbon nitride under simulated sunlight irradiation

The ubiquity of micropollutants (MPs) in aquatic environments has attracted increasing concern for public health and ecological security. Compared to conventional biological treatment, photocatalytic processes show more efficiency in degrading MPs, but they require expensive materials and complicated synthesis processes. This study developed an economic photocatalytic process to degrade micropollutants. We synthesized urea-based graphitic carbon nitride (g-C₃N₄) by a facile one-step pyrolysis method and evaluated the photocatalytic efficiency of carbamazepine (CBZ). Under simulated solar irradiation, g-C₃N₄ could achieve 100% removal efficiency of 0.1 mg/L CBZ in spiked wastewater effluent within 15 min, and 86.5% removal efficiency in wastewater influent after 20 min of irradiation. The porous structure of g-C₃N₄ promoted effective charge separation and mass transport of CBZ near the catalyst surface, enabling a high kinetic rate (0.3662 min ^-1). Reactive oxygen species trapping experiments revealed that superoxide radicals (O₂ ^•-) and holes (h⁺) were the major active radicals. Electron paramagnetic resonance (EPR) further confirmed the presence of O₂ ^•-, ^• OH, ¹O₂ and holes. The pH, light intensity and initial CBZ concentration were found to have significant impacts on the removal efficiency of CBZ. Possible reaction intermediates were identified and the degradation pathway was proposed. Multiple MPs were selected to further demonstrate photocatalytic efficiency of g-C₃N₄. The facile synthesis, superior efficiency, and versatility of g-C₃N₄ make it a promising catalyst for application in tertiary wastewater treatment processes.

An assessment of contamination fingerprinting techniques for determining the impact of domestic wastewater treatment systems on private well supplies

Private wells in Ireland and elsewhere have been shown to be prone to microbial contamination with the main suspected sources being practices associated with agriculture and domestic wastewater treatment systems (DWWTS). While the microbial quality of private well water is commonly assessed using faecal indicator bacteria, such as Escherichia coli, such organisms are not usually source-specific, and hence cannot definitively conclude the exact origin of the contamination. This research assessed a range of different chemical contamination fingerprinting techniques (ionic ratios, artificial sweeteners, caffeine, fluorescent whitening compounds, faecal sterol profiles and pharmaceuticals) as to their use to apportion contamination of private wells between human wastewater and animal husbandry wastes in rural areas of Ireland. A one-off sampling and analysis campaign of 212 private wells found that 15% were contaminated with E. coli. More extensive monitoring of 24 selected wells found 58% to be contaminated with E. coli on at least one occasion over a 14-month period. The application of fingerprinting techniques to these monitored wells found that the use of chloride/bromide and potassium/sodium ratios is a useful low-cost fingerprinting technique capable of identifying impacts from human wastewater and organic agricultural contamination, respectively. The artificial sweetener acesulfame was detected on several occasions in a number of monitored wells, indicating its conservative nature and potential use as a fingerprinting technique for human wastewater. However, neither fluorescent whitening compounds nor caffeine were detected in any wells, and faecal sterol profiles proved inconclusive, suggesting limited suitability for the conditions investigated.

Effects of Carbamazepine in Bivalves: A Review

Carbamazepine (CBZ) is among the ten most frequent pharmaceuticals that occur in the aquatic systems, with known effects on inhabiting organisms, including bivalves. Bivalves are important species in coastal ecosystems, often exhibiting a dominant biomass within invertebrate communities. These organisms play a major role in the functioning of the ecosystem and particularly in food webs (as suspension-feeders) and represent a significant fraction of the fisheries resource. They also have strong interactions with the environment, water and sediment and are considered good bioindicator species. The present paper reviews the known literature on the impacts of CBZ in biological endpoints of marine bivalves exposed to environmentally and non-environmentally relevant concentrations, highlighting differences in terms of biological responses, associated with exposure period, concentrations tested, and species used. Overall, the literature available showed that CBZ induces individual and sub-individual effects in marine bivalves (adults and life stages) and the most common effect reported was the induction of oxidative stress.

Optimization of the adsorption of diclofenac by activated carbon and the acidic regeneration of spent activated carbon

Diclofenac sodium (DCF) is a non-steroidal anti-inflammatory drug. It has been classified as ecotoxic even at low concentrations. In this study, adsorption of DCF on coconut shell-based granular activated carbon (GAC) and regeneration of spent GAC with hydrochloric acid (HCl) were investigated. The results showed that GAC with heterogeneous surface structure adsorbs DCF endothermically with both chemical and physical forces. Adsorption and regeneration processes were optimized with Taguchi Experimental Design. The effects of all parameters affecting the adsorption and regeneration processes were determined by analysis of variance and Pareto analyses. DCF removal of 79.80% was obtained at optimum conditions and the most effective parameter was evaluated as GAC size. At optimum regeneration conditions, 6.85 mg DCF/g GAC adsorption capacity was found with an operating cost of €0.05 g GAC. The amount of HCl was the most effective parameter. It was determined that the regenerated GAC had an adsorptive capacity higher than the adsorptive capacity of the raw GAC during at least three regeneration cycles. Raw, spent and regenerated GACs were characterized by Fourier transform infrared spectrometry and scanning electron microscopy analysis.

Characterization of the GABAergic system in Asian clam Corbicula fluminea: Phylogenetic analysis, tissue distribution, and response to the aquatic contaminant carbamazepine

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter involved in the neuro-endocrine-immune (NEI) system. In this study, we sequenced the partial length of cDNA fragments of three genes involved in GABA neurotransmitter system of the Asian clam (Corbicula fluminea) (GABA_A receptor-associated protein (GABARAP), GABARAPL2 and GABA transporter (GAT-1)). These genes exhibited high amino acid sequence identity compared with other invertebrate orthologs. Expression patterns of the three genes were determined in mantle, gill, gonad, digestive gland and muscle, and the steady state levels of mRNA for each were determined to be highest in gonad and lowest in muscle. To determine their regulation by pharmaceuticals that are present as contaminants in waterways, clams were exposed to carbamazepine (CBZ) for 30 days. CBZ is an agonist for GABA receptors and is an anticonvulsant pharmaceutical that is often detected in aquatic ecosystems. GABARAP and GABARAPL2 mRNA levels were significantly downregulated by 5 and 50 μg/L CBZ in mantle and gill (p < 0.05), while in the gonad and digestive gland, steady state levels (p < 0.05) were decreased with exposure to all three doses. GAT-1 mRNA was upregulated by CBZ (p < 0.05) in the mantle and gill at all three doses tested and in the gonad and digestive system with 5 and 50 μg/L. These data suggest that CBZ disrupt the expression of the GABAergic neurotransmitter system in C. fluminea. Moreover, GABARAP, GABARAPL2 and GAT-1 may be useful biomarkers for the screening of substances that are hazardous to the NEI system of mollusks.

The optimal method for peroxydisulfate quenching: A comparison of commonly used reductants

Peroxydisulfate-based advanced oxidation process has drawn increasing interest recently. Quenching the residual peroxydisulfate is essential for the accurate measurement of the concentration of target pollutants. However, it was rarely discussed which reductant is best for peroxydisulfate quenching. In this study, how the quenching of peroxydisulfate by four commonly used quenchers (methanol, ascorbic acid, sodium thiosulfate and sodium sulfite) affected the concentration of carbamazepine was investigated. Sodium sulfite reacted with carbamazepine directly, with the highest removal rate up to 39%. Higher carbamazepine removal rate was achieved by peroxydisulfate/sodium sulfite than by sodium sulfite alone. SO₃^•- and SO₅^•- rather than SO₄^•- played the major role in carbamazepine removal by sodium sulfite or peroxydisulfate/sodium sulfite. Methanol was found unable to reduce peroxydisulfate. Ascorbic acid, when used with a concentration more than three times higher than that of peroxydisulfate, was the best quencher with the lowest carbamazepine removal rate observed at a pH range of 3.5-10.0. Sodium thiosulfate was unfit for peroxydisulfate quenching at pH 3.5 as it was decomposed and formed bisulfite under strong acidic condition. The results of this study provided valuable guidance to the selection of proper quenchers for peroxydisulfate-related advanced oxidation processes.

Magnetic nanotechnology for diclofenac remediation: molecular basis of drug adsorption and neurobehavioral toxicology as a preliminary study for safe application

Diclofenac is a commercial non-steroidal anti-inflammatory drug commonly present as a pollutant in naturally occurring water sources and wastewaters. In this work, the adsorption of diclofenac onto chitosan-coated magnetic nanosystems is proposed as a possible tool for remediation. Experimental and theoretical studies have been carried out to reveal the mechanisms associated with diclofenac interactions among all the components of the nanosystem. Mechanisms are presented, analyzed and discussed. A toxicological study in mice was carried out to evaluate the parameters associated with neurotoxicity of the nanodevice. The elucidation of the mechanisms implied in the adsorption process of diclofenac onto magnetic chitosan nanocomposites suggests that diclofenac remediation from water is possible by adsorption onto chitosan. The strategy innovates the commonly used methodologies for diclofenac remediation from pharmaceutical wastes. This magnetic nanotechnology would not induce damage on the nervous system in a murine model, in case of traces remaining in water sources.

An innovative microbial electrochemical ultraviolet photolysis cell (MEUC) for efficient degradation of carbamazepine

Discharge of recalcitrant pharmaceuticals into aquatic environments can lead to serious negative environmental effects. While traditional wastewater treatment plants (WWTPs) are efficient for a wide range of non-toxic pollutants (i.e. ammonia), some wastewater streams contain recalcitrant toxic trace micropollutants such as pharmaceuticals that cannot be removed by the treatment processes that are typically employed in common WWTPs. Herein, an innovative 20 L microbial electrochemical ultraviolet photolysis cell (MEUC) was developed for the first time by the integration of a UV irradiation and a bioelectrochemical system, which exhibited efficient treatment of carbamazepine-a model pharmaceutical compound. Notably, neither the UV irradiation nor the bioelectrochemical system alone could effectively eliminate carbamazepine. The effect of operational parameters including applied voltage, cathodic aeration rate, UV intensity, and hydraulic retention time were evaluated. The obtained results elucidated that the degradation of carbamazepine was consistent with pseudo-first-order reaction kinetics, and required a lower energy input than traditional advanced oxidation processes. Five main transformation products were identified, and probable transformation pathways were established. Furthermore, the eco-toxicity as tested by Vibrio fischeri showed no significant bioluminescence inhibition by the treated carbamazepine effluent. Finally, the MEUC system was further tested with a real wastewater matrix, which again exhibited effective removal of carbamazepine. This paper provides a proof-of-concept verification of the novel MEUC system, which contributes insight for the subsequent vigorous development of the application of such efficient and cost-effective technologies for the treatment of trace pharmaceuticals wastewater.

Effective removal of carbamazepine and diclofenac by CuO/Cu2O/Cu-biochar composite with different adsorption mechanisms

In this study, the CuO/Cu₂O/Cu-biochar composite (CBC) was fabricated by calcining Cu²⁺-loaded cauliflower root at 500 °C. The CBC displayed the higher specific surface area and total pore volume than raw biochar, which attributed to Cu²⁺ acting as a pore-forming agent in the synthesis process. The adsorption experiments indicated that CBC could remove 88.96% diclofenac and 93.02% carbamazepine, which was nearly double higher than the raw biochar. The film diffusion mainly controlled the adsorption rate. Meanwhile, the common adsorption mechanisms for two pollutants were deemed to hydrogen-bonding interaction, π-π interaction and micropore filling effect, and copper oxide particles providing more adsorption sites. In addition, the adsorption of diclofenac involved electrostatic attraction. Lastly, the higher adsorption capacity of carbamazepine than diclofenac on CBC was mainly attributed to two mechanisms: Lewis acid-base interaction enhancing the adsorption of carbamazepine and size exclusion effect reducing the adsorption of diclofenac. Therefore, the study provided a possible method that Cu-contaminated biomass converted to CuO/Cu₂O/Cu-biochar, which could achieve win-win results.