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Graphical abstract Highlights • Photo-Fenton with Fe3+-EDDS removes CECs regardless water composition. • 80% CEC removal after 15 min in 5 real WWTP effluents. • Nature and not the load of organic matter has impact on CEC removal. • Short reaction time to remove CECs encourages continuous flow operation. • Mechanism developed with synthetic effluent explains reactions in real wastewater. Abstract This paper presents for the first time the treatment of contaminants of emerging concern (CECs) in a systematic study in different municipal wastewater treatment plants (MWWTPs) of the Mediterranean area, more than 1000 km away. Solar photo-Fenton process at neutral pH with Fe3+-EDDS has been demonstrated to be very efficient under controlled conditions and must be validated in realistic and variable conditions such as real MWWTP effluents of different composition. To this end, CEC removal was studied in effluents from 5 treatment plants in the Mediterranean area of Spain, the inorganic and organic composition varying in the range 161–641 mg L−1 (sulfate), 133–538 mg L−1 (chloride) and 10–20 mg L−1 (dissolved organic carbon). More than 45 CECs were quantified in MWW and results showed that the effect on CEC elimination of the concentration of anions and organic matter was interfered by the nature of the organic matter. However, origin and composition of MWW was not critic for attaining >80% degradation of CECs after 15 min of reaction. Moreover, conventional anions (sulfate, chloride) had a positive effect on CEC degradation rate. This paper demonstrates the consistency and predictability of the solar photo-Fenton process at circumneutral pH for treating CECs in simple and cheap photoreactors. [ABSTRACT FROM AUTHOR]

Water scarcity is a problem worldwide, affecting specially countries with desert/semi-desert areas and low/irregular rainfall. In this context, reuse of reclaimed wastewater (RWW) for agricultural irrigation is undoubtedly a key strategy to reduce fresh water consumption. It is well-known that current wastewater treatments do not effectively remove organic microcontaminants (OMCs), and research in water analysis of OMCs is extensive. However, the focus on agricultural soils irrigated with RWW as potential recipients of OMCs and potential sources of OMCs to crops is still in their beginnings. This study aims to apply a target and a suspect approach for the multi-residue monitoring of OMCs in agricultural soils and a soilless subtract, both irrigated with RWW for more than ten years. The study involved, firstly, the development and validation of an extraction method for target analysis of 73 OMCs using a QuEChERS-based method and liquid chromatography coupled to quadrupole-linear ion trap mass spectrometry (LC-QqLIT-MS/MS); and secondly, the application of a suspect workflow for the screening of a list of 1300 potential contaminants using LC coupled to quadrupole-time-of-flight MS (LC-QTOF-MS). The results demonstrated the occurrence of 11 OMCs in the agricultural soil samples and 26 in the soilless subtract (0.1–100 ng g −1 , dry weight, d.w.). The suspect analysis leaded to the confirmation of 28 OMCs analytes from the list of candidates. The subsequent combination of both strategies (suspect and target) revealed the presence of 11 new OMCs which were not previously reported. Furthermore, this study presents the first application of a OMCs suspect screening to agricultural soils irrigated with RWW for a long period. These results highlight the importance of monitoring soils with RWW-based irrigation and the application of wide-scope approaches for environmental analysis. [ABSTRACT FROM AUTHOR]

Abstract: An analytical methodology has been developed for the simultaneous extraction of 13 phenolic compounds, including chlorophenols (CPs), nitrophenols (NTPs), cresols and alkylphenols (APs) in different types of wastewater (WW) effluents. A solid-phase extraction (SPE) method has been optimized prior to the determination by gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS). Due to the complexity of the matrix, a comparison study of matrix-matched-calibration (MMC) and standard addition calibration (SAC) was carried out for quantification purposes. The optimized procedure was validated using the SAC approach since it provided the most adequate quantification results (in terms of recovery and precision values). Recoveries were in the range 60–135% (0.5μgL−1), 70–115% (1μgL−1), and 78–120% (5μgL−1), with precision values (expressed as relative standard deviation, RSD) ≤30% (except for 2-nitrophenol) involving intra-day and inter-day precision studies. Limits of detection (LODs) and quantification (LOQs) were also evaluated, and LOQs ranged from 0.03μgL−1 to 2.5μgL−1. The proposed method was applied to the analysis of 8 real WW effluent samples, finding some phenolic compounds (e.g. 2-chlorophenol, 2,4,6-trichlorophenol and 4-tert-octylphenol) at concentrations higher than the established LOQs. [Copyright &y& Elsevier]

rapid multi-analyte method has been developed for the simultaneous determination of pesticides and mycotoxins in milk by ultra high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS). A variety of methodologies has been evaluated, including solid-phase extraction (SPE), 'dilute-and-shoot' (liquid-liquid extraction-based procedures), and QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based methods. The optimization and development process was carried out considering that the maximum residue level for aflatoxin M1 (AFM1) in milk in the European Union (EU) is set at 0.05 μg kg, which is the lowest tolerance in the target compounds. The selected method consisted of an extraction by SPE using C18 as sorbent and methanol as elution solvent. The final determination was performed by UHPLC-QqQ-MS/MS. Matrix-matched standard calibration was used for quantification, obtaining recoveries in the range 60-120% with relative standard deviations <25%, at three spiking levels: 0.5, 10, and 50 μg kg (ten times lower for AFM1). Limits of quantification ranged from 0.20 to 0.67 μg kg, which were always below or equal to the established tolerance levels by the EU. Finally, the selected method was applied to different types of milk. [ABSTRACT FROM AUTHOR]

Abstract: Pesticides are widely applied and they can produce a variety of transformation products (TPs), through different pathways and mechanisms. Nowadays there is a growing interest related to the determination of pesticide TPs in several matrices (environmental, food and biological samples), due to these compounds can be more toxic and persistent than parent compounds, and some of them can be used as markers of exposure to different pesticides. Although solid-phase extraction (SPE) is mainly used for the extraction of TPs, alternative techniques such as solid-phase microextraction (SPME) and liquid-phase extraction (LPE) can be used. These TPs are mainly determined by liquid chromatography (LC) due to the recent developments in this technique, especially when it is coupled to mass spectrometry (MS) detectors, allowing the determination of known and/or unknown TPs. Furthermore, MS is a very valuable tool for the structural elucidation of unknown TPs. This review discusses all phases of analytical procedure, including sample treatment and analysis, indicating the main problems related to the extraction of TPs from several matrices due to their high polarity, as well as the different alternatives found for the simultaneous determination of parent compounds and TPs, using chromatographic techniques coupled to MS detection. [Copyright &y& Elsevier]

• A QuEChERS-based method has been validated for the determination of 107 CECs in TWW. • QuEChERS-based methods demonstrate their suitability to analyze CECs in wastewater. • Recovery ranged from 70–120% for 89% of the target CECs at 50 and 500 ng L−1. • LOQs were ≤ 50 ng L−1 for 89% of the target CECs. • Analyses of treated wastewater samples using the validated method (35 CECs detected). The inefficiency of wastewater treatment plants (WWTPs) to remove contaminants of emerging concern (CECs) leads to their continuous release to the environment. Consequently, CECs are present at low concentrations in the treated wastewater (TWW), producing unpredicted and unwanted effects on living organisms as they are discharged into water receiving bodies. This work presents a fast and reliable method for the determination of CECs in TWW based on the innovative application of a QuEChERS (quick, easy, cheap, effective, rugged and safe) method for water extraction and determination by sensitive liquid chromatography coupled to quadrupole-linear ion trap tandem mass spectrometry (LC-QqLIT-MS/MS). The scope of the proposed QuEChERS-based method allows the monitoring of 107 CECs, including pharmaceuticals (58), antibiotics (16) and pesticides (33). The proposed method was successfully validated in urban TWW at two concentration levels (50 and 500 ng L−1) and it is a feasible alternative to conventional and time-consuming solid-phase extraction (SPE) methodologies. 89% of the CECs presented mean recovery values in the 70–120% range with relative standard deviations (RSDs) always < 20% (intra and inter-day precision), and limits of quantification (LOQs) in the range 5–500 ng L−1 (89% of the compounds showed a LOQ ≤ 50 ng L−1). The applicability of the method was demonstrated by the analysis of urban TWW samples (7 sampling events). In total, 35 CECs (23 pharmaceuticals, 2 antibiotics and 10 pesticides) were detected in the monitored samples with concentrations ranging from 5 to 677 ng L−1. [ABSTRACT FROM AUTHOR]

Abstract: Gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) is one of the most powerful techniques in pesticide residue analysis. MS/MS can be conceived in two ways: tandem in space (e.g. triple quadrupole, QqQ) or in time (e.g. ion trap, IT). QqQ and IT are commonly interfaced to GC; however, there has not been any direct comparison between them in pesticide residue analysis so far. In the present work, the performance of GC coupled to these two analyzers (GC–QqQ–MS/MS and GC–IT–MS/MS) was studied and compared for pesticide residue analysis as well as its application in food analysis. The large volume injection (LVI) technique together with programmed-temperature vaporization (PTV) was applied. For this purpose, 19 pesticides, including organochlorine and organophophorus pesticides and pyrethroids, were analyzed in both systems. Mass spectrometric data, performance characteristics (linearity, intra-day and inter-day precision) and the influence of the matrix nature on the analysis of low concentrations were compared. The target compounds were analyzed in solvent and in two representative food matrices such as cucumber (high water content) and egg (high fat content). MS data and intra-day precision were similar in QqQ and IT, whereas inter-day precision was significantly worse in QqQ. Linearity (expressed as determination coefficient, R 2) in the range 10–150μgL−1 was adequate in both systems; however, better R 2 values were obtained with the QqQ analyzer in high and low concentration ranges (1–50 and 1–750μgL−1, respectively). The influence of the matrix nature on the analysis of low concentrations of each analyzer was also evaluated. The QqQ and IT performance was similar in cucumber and solvent. However, QqQ provided better sensitivity in egg working in selected reaction monitoring (SRM). [Copyright &y& Elsevier]

The transformation that pharmaceuticals can undergo during the water reclamation cycle, or by biotic/abiotic reactions when reclaimed water (RW) is used for irrigation, can lead to the presence of transformation products (TPs) in agricultural environments. However, data on TPs in real crops are scarce. Herein, a suspect screening approach was applied for the comprehensive investigation of 262 potential TPs, associated with 20 prioritised pharmaceuticals found in real tomato crops exposed to long-term RW irrigation. The occurrence and fate of the TPs was evaluated by the retrospective analysis of RW, soil, leave and tomato samples from 4 intensive production greenhouses. Sample analysis was accomplished by liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). Up to 18 TPs were tentatively identified, of which 2 were not previously reported. 7 TPs were finally confirmed with analytical standards. 5 TPs were determined in RW, 15 TPs in soil and 2 TPs in leaves. Remarkably, the investigated TPs were not found in tomato fruits. These results shed light on the variety of TPs that can be found in the water reuse cycle and contribute to the assessment of the global risks of wastewater reuse and the safety of the vegetable and fruit production system. [Display omitted] • LC-QTOF-MS suspect screening to evaluate 262 TPs in agroecosystems. • 18 TPs tentatively identified and 7 confirmed in reclaimed water, soil and leaves. • None of the investigated TPs were detected in the analysed tomato fruits. • Potential spread of antibiotic resistance due to detected active antibiotic TPs. • Additional research is needed in other crops and reclaimed water agro-ecosystems. [ABSTRACT FROM AUTHOR]

• Addition of landfill leachates treated by solar photo-Fenton to biological systems. • Treatment effectiveness: evaluation of organic microcontaminant (OMC) removal. • Evaluation using target and suspect analysis by LC–MS/MS, LC-QTOF-MS and GC–MS. • Treated leachate: reduction of 94% of the initial quantified OMC concentration. • Detection of 3 non-reported OMCs: di- n -nonyl phthalate, o -phenylphenol and tonalide. Conventional wastewater treatments are not usually effective in the remediation of specific landfill leachates due to their high content in toxic and recalcitrant compounds. Advanced and intensive treatments are needed for the decontamination and possible recycling of these effluents. Here, the combination of advanced oxidation processes (solar photo-Fenton) and an aerobic biological reactor have been applied to treat urban landfill leachates. The effectiveness of the proposed treatment line was also evaluated considering the removal of organic microcontaminants (OMCs) identified in the different phases, which is an innovative practice. The analytical strategy included: (i) a target approach (115 analytes) by liquid chromatography-mass spectrometry (LC–MS/MS); and two suspect approaches using (ii) LC-high-resolution MS (database with >1300 compounds) and (iii) gas-chromatography-MS (database with >900 compounds). OMCs on the treated landfill leachate was reduced up to 94% of the initial concentration. 8 target compounds (mainly pharmaceuticals) out of 115 target analytes represented 85% of the OMC concentration in the raw leachate: cotinine, diclofenac, gabapentin, ketoprofen, lidocaine, mecoprop, nicotine and trigonelline. 3 non-previously reported OMCs were confirmed: di- n -nonyl phthalate, o -phenylphenol and tonalide. Leachate partially oxidized by solar photo-Fenton process can be successfully incorporated to biological systems to complete the treatment by means of specifically adapted biomass. [ABSTRACT FROM AUTHOR]

Abstract: Veterinary drugs (VDs) can remain in milk as a consequence of their use in livestock. In order to control the levels of VD residues in milk, screening methodologies can be applied for a rapid discrimination among negative and non-negative samples. In a second stage, non-negative samples are classified as negative or positive samples by using a confirmation method. Pre-target screening methods in low resolution MS (LRMS) are normally applied, but the number of analytes is limited, whereas the information obtained by full scan acquisition in high resolution mass spectrometry (HRMS) is improved. Here, three screening methods (running time<4min) based on Orbitrap, quadrupole-time of flight (QqTOF) and triple quadrupole (QqQ) have been compared, using in all cases ultra-high performance liquid chromatography (UHPLC). For HRMS, the identification of the VDs was based on retention time (RT) and accurate mass measurements. Confirmation was based on the monitoring of fragments generated without precursor selection. The performance characteristics of the screening method provided reliable information regarding the presence or absence of the compounds below an established value, including uncertainty region and cut-off values. Better results in terms of cut-off values (≤5.0μgkg−1, except for spiramycin with a cut-off of 13.4μgkg−1 for milk samples and 43.1μgkg−1 for powdered milk based, emamectin with a cut-off of 42.2μgkg−1 for milk samples and doxycycline, with a cut-off value of 15.8μgkg−1 in powdered milk-based infant formulae) and uncertainty region were obtained using the Orbitrap-based screening method, which was submitted to further validation and used to analyze different real milk samples. The proposed method can be used in routine analysis, providing reliable results. [Copyright &y& Elsevier]

• Photo-Fenton at neutral pH leads to simultaneous disinfection and CEC removal. • Apparent kinetic constants linearly increase when decreasing liquid depth. • The cost ranges from 0.13 to 0.49 €/m3 regarding treatment goal. • Operating cost with Fe3+-EDDS is around 50–75 % higher than with FeSO 4. • Photo-Fenton with Fe3+-EDDS removes 80 % CECs, while only 35 % is removed with FeSO 4. For the first time, two strategies of solar photo-Fenton at neutral pH (with FeSO 4 and Fe3+-EDDS) are techno-economically assessed. With the target of simultaneous wastewater disinfection and removal of contaminants of emerging concern (CECs), a cost estimation ranging from 0.13 to 0.49 €/m3 as a function of the treatment goal is presented. To this end, the effects of liquid depth (5, 10 and 15 cm) and the iron species were studied at lab-scale. Afterwards, the feasibility of both operating strategies was evaluated and validated outdoors at pilot plant scale in low-cost raceway pond reactors. For the joint-removal of bacteria and CECs, the use of FeSO 4 as iron source was cheaper than Fe3+-EDDS. However, it is important to highlight that although bacterial inactivation reached > 3 log, only around 35 % of CEC degradation was achieved with FeSO 4 , while more than 80 % CEC load was removed with Fe3+-EDDS. [ABSTRACT FROM AUTHOR]

[Display omitted] • 4 different SR-AOPs were tested at pilot scale for real wastewater reclamation. • PMS/H 2 O 2 /UV-A (molar ratio 1:3) treatments enhances disinfection performance. • PMS/H 2 O 2 /UV-A does not improve CECs and ARGs removal compared with PMS/UV-A. • PMS/O 3 removes 94% of the CECs, 6 out of the 8 ARGs, and provides simultaneous disinfection. • Despite the high efficiency of PMS/O 3 system, it showed higher phytotoxicity. Wastewater reuse addresses water scarcity, but contaminants of emerging concern (CECs), pathogens and antibiotic resistance genes (ARGs) pose health and environmental risks. The European Union (EU) has enacted Regulation (EU) 2020/741, establishing wastewater reuse standards for agriculture. This study evaluates for the first time the effectiveness of four sulfate radical-based advanced oxidation processes (SR-AOPs), based on the combination of peroxymonosulfate (PMS) with O 3 and H 2 O 2, applied at pilot plant, for the simultaneous elimination of microorganisms, CECs, and ARGs, in actual urban wastewater treatment plant (UWWTP) effluents. The system PMS/H 2 O 2 /UV-A improved the disinfection effectiveness, compared to PMS/UV-A, especially using a molar ratio 1:3 (0.5 mM PMS:1.5 mM H 2 O 2), achieving complete elimination of total aerobic microorganisms in 90 min. However, this double oxidation system, does not improve CECs removal compared to PMS/UV-A in neither of the two molar ratios studied (1:1 or 1:3), and none of these treatments significantly reduced the prevalence of ARGs. However, the PMS/O 3 system demonstrated the ability to remove total aerobic microorganisms in 20 min and Escherichia coli in 5 min, 94 % of CECs, and 6 out of the 8 ARGs, demonstrating to be the most effective treatment. However, the system showed phytotoxicity, inhibiting seed growth by 10–30 %, probably associated with the by-products formed in the reaction between organic matter and ozone. This result highlights that SR-AOPs are promising processes with the capability to achieve the simultaneous removal of different contaminant groups, reducing the risks associated with wastewater reuse. Their application at larger scales is increasingly closer. [ABSTRACT FROM AUTHOR]

A novel strategy based on solar photo-Fenton mediated by ferric nitrilotriacetate (Fe3+-NTA) combined with NaOCl in continuous flow mode for wastewater reclamation has been studied. Escherichia coli (E. coli) inactivation attained ≥ 5 log10-units, meeting the most restrictive EU 2020/741 target (10 CFU/100 mL), and 75% of organic microcontaminant total load was removed. As a remarkable finding, trihalomethanes (THMs) concentration was insignificant, complying by far with the Italian legislation limit. To attain these results, first the effect of liquid depth on E. coli inactivation and imidacloprid (IMD) removal from spiked municipal effluents was evaluated in continuous flow pilot-scale raceway pond reactors at 60-min hydraulic residence time with low reagent concentrations (0.10 mM Fe3+-NTA, 0.73 mM H 2 O 2 and 0.13 mM NaOCl). Disinfection was due to the bactericidal effect of chlorine. In contrast, liquid depth notably influenced microcontaminant removal, highlighting that operation at 10-cm liquid depth allows achieving treatment capacities higher than at 5 cm (16.50 vs 28.20 mg IMD/m2∙day). Next, the monitoring of THMs was carried out to evaluate the generation and degradation of disinfection by-products, along with the removal of actual microcontaminants. These promising results draw attention to the treatment potential and open the way for its commercial application. [Display omitted] • Continuous flow operation of solar photo-Fenton combined with NaOCl was assessed. • Liquid depth affected microcontaminant removal; disinfection was due to NaOCl. • > 75% microcontaminants were removed in 10-cm deep reactor at 60 min of HRT. • E. coli inactivation was ≥ 5 log-units meeting EU 2020/741 target. • Trihalomethanes' concentration was 7.5–10 fold below the mandatory limit regulated. [ABSTRACT FROM AUTHOR]

Continuous flow solar photo-Fenton process has been carried out at demonstration scale at flow rates up to 18 m3 h−1 as an advanced treatment for the removal of contaminants of emerging concern, CECs. A 100-m2 raceway pond reactor, RPR, has been built in the WWTP of Almeria city, Spain. The fluid dynamics study showed plug-flow in the reactor channels and perfect mixing in the bends and paddlewheel sections, giving rise to long mixing times. Consequently, for CEC removal the RPR was operated in continuous flow mode at 1 h of hydraulic residence time and acidic pH, with 0.1 mM FeSO 4 and 1.47 mM H 2 O 2. Liquid depth was set at 10 cm in winter and 18 cm in summer, achieving > 85% of CEC removal in both cases. For the first time, CEC removal by solar photo-Fenton has been demonstrated under real operational conditions paving the way for its commercial application. [Display omitted] • The solar photo-Fenton process has been implemented at large scale for CEC removal. • More than 85% CECs were removed from secondary effluents in a 100-m2 RPR. • 144 m3 day−1 operating 8 h day−1 with 18 cm of liquid depth at 60 min of HRT. • Kinetics and RPR flow pattern play an important role when scaling up the process. [ABSTRACT FROM AUTHOR]

Abstract: The assessment of the recovery factor with the analyte concentration in meat samples has been studied for the determination of organochlorine and organophosphorus pesticides in meat by gas chromatography-triple quadrupole mass spectrometry (GC–MS/MS). For that purpose, recent IUPAC recommendations, which distinguishes between two terms, recovery factor and apparent recovery, have been followed. Besides, the systematic error due to the matrix effect has been evaluated by a new term recently proposed, calibration recovery. Recovery profiles were obtained analyzing spiked blank matrix, where the analytes were added before and after the extraction procedure. In a first step, the quantification of the compounds was carried out using a solvent calibration curve. The systematic errors due to the matrix effect during the quantification step and the error due to the sample treatment have been evaluated. Both apparent and calibration recovery components depend on the actual analyte concentration in the sample while the recovery factor remains constant except for analyte concentration close to quantification limit. In addition, the concentration limits, from which an acceptable recovery value (70–110%) can be obtained, are given. If spiked samples are quantified by matrix-matched calibration, the matrix effect is minimized and the calibration recovery component is 100%, and apparent recovery only depends on the recovery factor. The obtained values indicate recovery factor does not depend on the analyte concentration, except for those values closed to quantification limit. [Copyright &y& Elsevier]

Abstract: A method was optimized and validated for the simultaneous determination of residues of organochlorine (OCPs) and organophosphorus (OPPs) pesticides in meat samples from chicken, pork and lamb. The method is based in the extraction of homogenized meat mixed with sodium sulphate and ethyl acetate in polytron, although both Soxhlet and accelerated solvent extraction (ASE) were also tested. Then, a clean-up step by gel permeation chromatography (GPC) was applied, before the final determination by gas chromatography (GC) coupled to a triple quadrupole (QqQ) mass spectrometry (MS) detection system. Confirmation criteria of the pesticides were based in the 2002/657/EC European Commission Decision that establishes at least three identification points (IPs) for organic residues in live animals and animal products. The analytical process was validated in each matrix by the analysis of spiked blank samples. Performance characteristics, such as linearity, detection limit (LOD), quantitation limit (LOQ), precision and recovery were studied. Recoveries and precision values were 70.0–90.0% and 15%, respectively, for the bulk majority of pesticides. LOD<2.0 and LOQ<5.0μg/kg were obtained for all the target compounds, except for acephate. The proposed analytical methodology was applied to the analysis of the pesticides in 30 samples, 10 from chicken, 10 from pork and 10 from lamb. Only three OCPs, endosulfan α, endosulfan sulfate and dichloran were detected in three different lamb samples, while endosulfan α was detected in only one pork sample, at concentration levels lower than the LOQ values. However, pesticide residues were not found in any of the other 10 chicken samples analyzed. [Copyright &y& Elsevier]

As far as the authors know, no in-depth comparison has been made between the different performances of the solar photo-Fenton process for the removal of contaminants of emerging concern (CECs) as a function of pH. To this end, real WWTP secondary effluents were treated in continuous flow mode at pilot plant scale. The effect of hydraulic residence time (HRT), liquid depth and percentage of CEC removal on treatment capacity was studied. At acidic pH (2.8), the iron source was FeSO 4 and at neutral pH (7.0), it was Fe(III)-EDDS. At both pH values, 2250 L m−2 d−1 can be treated in 15-cm deep raceway pond reactors at 30 min HRT with 0.1 mM iron and 0.88 mM H 2 O 2 in order to achieve 80% CEC removal. Treatment costs were 0.25 € m−3 and 0.56 € m−3 at acidic and neutral pH, respectively. This study paves the way for the solar photo-Fenton process to be employed on a commercial scale. Unlabelled Image • In-depth comparison between acidic and neutral pH solar photo-Fenton for CEC removal • At acidic pH, the iron source was FeSO 4 and at neutral pH, the complex Fe(III)-EDDS. • The effect of HRT, liquid depth and CEC removal goal on treatment capacity was studied. • 2250 L m−2 d−1 treated in 15-cm deep RPRs at 30 min of HRT, 0.1 mM Fe, 0.88 mM H 2 O 2 • Unitary costs were estimated as 0.25 € m−3 and 0.56 € m−3 at acidic and neutral pH. [ABSTRACT FROM AUTHOR]

• A tool to design raceway pond reactors for solar photo-Fenton is proposed. • Kinetic model with Fe3+-EDDS predicts the continuous CEC removal in real wastewater. • Simulations show high CEC removal and Fe3+-EDDS conversion at short HRT. • Reactor area is estimated as a function of HRT, liquid depth and UV irradiance. • Deeper photoreactors could be used, the treatment capacity being strongly increased. This work presents for the first time a tool for the design of continuous raceway pond reactors to remove contaminants of emerging concern (CECs) from WWTP secondary effluents by solar photo-Fenton process at neutral pH. The effects of the hydraulic residence time (HRT) and the liquid depth on the treatment capacity were studied, the availability of solar UV radiation being the main environmental variable. Treatment capacities as high as 1800 and 9000 L m−2 d-1 were estimated for 70% CEC removal in winter and summer, respectively. To this aim, the performance of a kinetic model of the photo-Fenton process developed with Fe3+-EDDS was updated to predict CEC removal in effluents collected from different WWTPs. To reach a goal of CEC elimination, the treatment capacity can be maximized as a function of HRT and liquid depth, and consequently the reactor surface area is calculated to treat a given flow rate. [ABSTRACT FROM AUTHOR]