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Highlights: [•] Continuous and sequential iron dosage allowed micropollutants removal at natural pH. [•] Bicarbonates were detrimental to the process efficiency when using iron additions. [•] Iron addition mode affects reaction time and efficacy. [•] Continuous addition allows a better distribution of iron in the photo-reactor. [•] Acetamiprid, thiabendazole and imazalil degradation could be achieved in 15min. [Copyright &y& Elsevier]

Abstract: This study compares two different solar photo-Fenton processes, conventional photo-Fenton at pH3 and modified photo-Fenton at neutral pH with minimal Fe (5 mg L−1) and minimal initial H2O2 (50 mg L−1) concentrations for the degradation of emerging contaminants in Municipal Wastewater Treatment Plants effluents in solar pilot plant. As Fe precipitates at neutral pH, complexing agents which are able to form photoactive species, do not pollute the environment or increase toxicity have to be used to keep the iron in solution. This study was done using real effluents containing over 60 different contaminants, which were monitored during treatment by liquid chromatography coupled to a hybrid quadrupole/linear ion trap mass analyzer (LC-QTRAP-MS/MS) operating in selected reaction monitoring (SRM) mode. Concentrations of the selected contaminants ranged from a few ng L−1 to tens of μg L−1. It was demonstrated in all cases the removal of over 95% of the contaminants. Photo-Fenton at pH3 provided the best treatment time, but has the disadvantage that the water must be previously acidified. The most promising process was photo-Fenton modified with Ethylenediamine-N,N′-disuccinic acid (EDDS), as the pH remained in the neutral range. [Copyright &y& Elsevier]

Abstract: Nowadays there is a continuously increasing worldwide concern for development of alternative water reuse technologies, mainly focused on agriculture and industry. In this context, Advanced Oxidation Processes (AOPs) are considered a highly competitive water treatment technology for the removal of those organic pollutants not treatable by conventional techniques due to their high chemical stability and/or low biodegradability. Although chemical oxidation for complete mineralization is usually expensive, its combination with a biological treatment is widely reported to reduce operating costs. This paper reviews recent research combining AOPs (as a pre-treatment or post-treatment stage) and bioremediation technologies for the decontamination of a wide range of synthetic and real industrial wastewater. Special emphasis is also placed on recent studies and large-scale combination schemes developed in Mediterranean countries for non-biodegradable wastewater treatment and reuse. The main conclusions arrived at from the overall assessment of the literature are that more work needs to be done on degradation kinetics and reactor modeling of the combined process, and also dynamics of the initial attack on primary contaminants and intermediate species generation. Furthermore, better economic models must be developed to estimate how the cost of this combined process varies with specific industrial wastewater characteristics, the overall decontamination efficiency and the relative cost of the AOP versus biological treatment. [Copyright &y& Elsevier]

Abstract: As normal municipal wastewater treatment plants (MWTP) are not able to entirely degrade xenobiotic substances, this study focuses on modified solar photo-Fenton treatment (5mgL−1 Fe, initial pH≈7) of a municipal wastewater treatment plant (MWTP) effluent. However, effluents do not contain compounds which could form photoactive Fe3+ complexes. The use of ferrioxalate, humic substances (HA) and mixing the MWTP effluent with small amounts of influent could be justified to form photoactive Fe3+ complexes. All experiments were done in MWTP effluent spiked (5 or 100μg/L) with 15 emerging contaminants (ECs) using a pilot compound parabolic collector (CPC) solar plant designed for solar photocatalytic applications. Dissolved organic carbon and UPLC–UV (with prior solid phase extraction) were applied for evaluating the results. The oxalate-enhanced process provided satisfactory EC degradation results but low residual pH of the treated water. HA (10mgL−1) enhanced the process, balancing degradation time and residual pH. Mixing of MWTP influent and effluent delivered rather disappointing results, as EC degradation was unsuccessful in all cases tested. [Copyright &y& Elsevier]

Abstract: This work is proposing a design strategy for an industrial combined solar photo-Fenton/aerobic biological system for the decontamination of wastewater polluted with commercial pesticides. The two possibilities (photo-Fenton/bio and Bio/photo-Fenton) of the combined system were evaluated (using different analytical tools and bioassays, mainly DOC, COD, toxicity and biodegradability) in pilot plant and the most successful was scaled-up. Photo-Fenton (20mg/L of Fe2+) was carried out in compound parabolic collectors (CPC) at an initial DOC of 500mg/L (100mg/L of each commercial pesticide). The biological pilot reactor was an Immobilized Biomass Reactor (IBR) filled with polypropylene Pall Ring® supports colonized by activated sludge. The industrial plant has a total collector surface of 150m2, total photo reactor volume of 1060L and the scaled-up biological treatment plant (also an IBR) consists basically of two IBRs (1230L each). The photo-Fenton treatment at pilot plant scale was able to reduce toxicity (from 96% to 50% of inhibition) and increase biodegradability (from 50% to 95%) of the wastewater and the most suitable point for combining it with the biological treatment was after the total elimination of the active ingredients. The efficiency of the combined photo-Fenton/bio system in terms of mineralization was 94%, of which 35.5% corresponds to the AOP and 58.5% to the aerobic biological treatment. The combination Bio/photo-Fenton was not successful. The efficiency of the industrial-scale combined system (photo-Fenton/bio) was 84%, 35% corresponding to the photo-Fenton treatment and 49% to the biological stage. [Copyright &y& Elsevier]

This work focuses on the treatment of real effluents from a municipal wastewater treatment plant (RE) with solar photo-Fenton (5 mg and 20 mg L-1 Fe, pH ∼ 3 and 50 mg L-1 initial H2O2 concentration) at pilot plant scale. In some experiments RE was spiked with 15 different (acetaminophen, antipyrine, atrazine, caffeine, carbamazepine, diclofenac, flumequine, hydroxybiphenyl, ibuprofen, isoproturon, ketorolac, ofloxacin, progesterone, sulfamethoxazole, and triclosan) emerging contaminants (ECs) at 100 and 5 μg L-1 each which were added directly into RE prior to treatment. All experiments showed successful degradation of ECs in real effluents from different municipal wastewater treatment plants at low iron concentration (5 mg L-1). Although the most degradation took place during the Fenton process, photo-Fenton was necessary to degrade all ECs below their limit of detection (LOD). In the case of the RE containing 52 ECs (determined by HPLC-QTRAP-MS), four of them could not be degraded to their LOD and were still present, although at extremely low concentrations (nicotine 47 ng L-1, cotinine 11 ng L-1, chlorfenvinphos 99 ng L-1, and caffeine 8 ng L-1). ECs were easily degraded by •OH without substantial competition with the organic content of the RE. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, there has been a tremendous amount of research and development in the area of photocatalysis (heterogeneous and homogeneous), a process included in a special class of oxidation techniques defined as Advanced Oxidation Processes (AOPs), all characterized by the same chemical feature, production of ls. This paper reviews the use of sunlight to produce the ls by TiO2 photocatalysis and photo-Fenton process. The reacting systems necessary for performing solar photocatalysis are described. The paper also summarizes most of the research carried out related to solar photocatalytic degradation of water contaminants, and how it could significantly contribute to the treatment of persistent toxic compounds. It outlines how to enhance the process efficiency by integration with biotreatment. Various solar reactors for photocatalytic water treatment mainly based on non-concentrating collectors built during the last few years are also described in detail in this review, as well as the use of the solar photocatalytic processes to inactivate microorganisms present in water, placing special emphasis on experimental systems made to optimize this disinfection technique. [Copyright &y& Elsevier]

Abstract: In the context of an upcoming energy crisis due to the decline of the Oil Era, water problems are expected to substantially worsen. And vice versa, due to the close relationship between water and energy issues, water problems are also expected to contribute to increased energy problems. Furthermore, environmental considerations, such as global warming, will surely add significant pressure. In this scenario, renewable energies are rapidly increasing their contribution to the global mix, with solar energy clearly having the greatest potential, and in view of the worldwide coincidence that where there is water stress and/or scarcity, there are also good solar radiation levels, the conclusion seems clear suitable technologies must be developed to permit the use of solar energy to simultaneously help solve energy and water problems. The main solar energy applications for water processes presented in this paper are: (i) solar desalination; (ii) solar detoxification and; (iii) solar disinfection. [Copyright &y& Elsevier]

Abstract: A mixture of five pesticides commonly used in intensive agriculture in the southeast of Spain, Methomyl, Dimethoate, Oxamyl, Cymoxanil and Pyrimethanil, has been completely mineralized in a combined solar photocatalytic–biological pilot plant. Two advanced oxidation processes (AOPs: TiO2 and photo-Fenton) were employed for enhancing the biodegradability of wastewater and an aerobic immobilised biomass reactor (IBR) was used for the following continuous biological treatment. TiO2 photocatalysis experiments were performed in a 35-L solar pilot plant made up of three compound parabolic collectors (CPCs), whereas photo-Fenton tests were carried out in a 75-L solar pilot plant with four CPCs units. The initial pesticide concentrations in the mixture were 50mgL−1 each. The TiO2 catalyst concentration employed was 200mgL−1, and two different Fe2+ concentrations, 20mgL−1 and 55mgL−1, were used in the photo-Fenton tests. Toxicity (Vibrio fischeri) and biodegradability assays (Zahn-Wellens test) were also performed to monitor toxicity and biodegradability of samples at different stages of photo-Fenton treatment. Biodegradable compounds generated during the preliminary oxidative process were mineralized in a 60-L activated sludge biological reactor filled with 30L of propylene Pall Ring supports. Total disappearance of the parent compounds, more than 90% mineralization and complete nitrification were achieved by the combined system. [Copyright &y& Elsevier]

Two advanced oxidation processes (AOPs/, ozonation and photo-Fenton, combined with a pilot aerobic biological reactor at field scare were employed for the treatment of industrial non-biodegradable saline wastewater (TOC around 200 mg L -1) containing a biorecalcitrant compound, α-methylphenylglycine (MPG), at a concentration of 500 mgL-1. Ozonation experiments were performed in a 50-L reactor with constant inlet ozone of 21.9 g m-3. Solar photo-Fenton tests were carried out in a 75-L pilot plant made up of four compound parabolic collector (CPC) units. The catalyst concentration employed in this system was 20mgL-1 of Fe2+ and the H2O2 concentration was kept in the range of 200-500mgL-1. Complete degradation of MPG was attained after 1, 020 min of ozone treatment, while only 195 mm were required for photo-Fenton. Samples from different stages of both AOPs were taken for Zahn-Wellens biocompatibility tests. Biodegradability enhancement of the industrial satine wastewater was confirmed (> 770% biodegradability). Biodegradable compounds generated during the preliminary oxidative processes were biologically mineralised in a 170-L aerobic immobilised biomass reactor (IBR). The global efficiency of both AOP/biological combined systems was 90% removal of an initial TOC of over 500 mg L-1. [ABSTRACT FROM AUTHOR]

Abstract: A coupled solar photocatalytic-biological pilot plant system has been employed to enhance the biodegradability and complete mineralization of a biorecalcitrant industrial compound, α-methylphenylglycine, dissolved in distilled water and simulated seawater at 500mgL−1. The pollutant was completely degraded by a solar photo-Fenton treatment in a 75-L pilot plant made up of four compound parabolic collector (CPC) units. The catalyst concentration employed was 2 and 20mgL−1 of Fe2+ and the H2O2 concentration was kept in the range of 200–500mgL−1. A Zahn–Wellens (Z–W) test applied to photo-treated samples demonstrated that intermediates produced within a short time of starting the photo-Fenton process were biodegradable. Consequently, the photocatalytic and biological processes were combined. Biodegradable compounds generated during the preliminary oxidative process were biologically mineralized in a 170-L aerobic immobilised biomass reactor (IBR), filled with 90–95L propylene Pall® Ring supports colonized by activated sludge. Almost total mineralization (90% overall total organic carbon removed) was attained in the combined treatment system (for both distilled and seawater experiments). Moreover, nitrification and denitrification phenomena were also observed. [Copyright &y& Elsevier]

Abstract: Aqueous solutions of a mixture of several pesticides (alachlor, atrazine, chlorfenvinphos, diuron and isoproturon), considered PS (priority substances) by the European Commission, and an intermediate product of the pharmaceutical industry (α-methylphenylglycine, MPG) chosen as a model industrial pollutant, have been degraded at pilot-plant scale using ozonation. This study is part of a large research project [CADOX Project, A Coupled Advanced Oxidation-Biological Process for Recycling of Industrial Wastewater Containing Persistent Organic Contaminants, Contract No.: EVK1-CT-2002-00122, European Commission, http://www.psa.es/webeng/projects/cadox/index.html] founded by the European Union that inquires into the potential coupling between chemical and biological oxidations for the removal of toxic or non-biodegradable contaminants from water. The evolution of pollutant concentration, TOC mineralization, generation of inorganic species and consumption of O3 have been followed in order to visualize the chemical treatment effectiveness. Although complete mineralization is hard to accomplish, and large amounts of the oxidant are required to lower the organic content of the solutions, the possibility of ozonation cannot be ruled out if partial degradation is the final goal wanted. In this sense, Zahn–Wellens biodegradability tests of the ozonated MPG solutions have been performed, and the possibility of a further coupling with a secondary biological treatment for complete organic removal is envisaged. [Copyright &y& Elsevier]

A new granulated version of the well-known P-25 titanium dioxide (VP AEROPERL® P-25/20 (Aeroperl)) has been tested to determine whether its photocatalytic efficiency is good enough for use in photocatalytic water purification and to find out if it can be separated from water more easily than its well-known homologue, powdered Degussa P-25, a significant technical improvement that might eliminate the tedious final filtration necessary with a slurry. Furthermore, a new commercial catalyst (PC-100 from Millennium Inorganic Chemicals), having a surface area and structure that are both different from Degussa P-25, has also been studied. All the experiments were carried out in sunlight in the pilot compound parabolic collector (CPC) plant at the Plataforma Solar de Almerı´a. Three different substrates were chosen as model molecules for this study: dichloracetic acid, phenol and the pesticide imidacloprid. Results show that Degussa Aeroperl is not a good alternative to powdered Degussa P-25 because of its spontaneous sedimentation during photocatalysis. Millennium PC-100 efficiency seems to be in the same range as that of Degussa P-25. In this work we also attempt to demonstrate that the comparison of efficiencies of different photocatalysts is not a trivial matter. Many factors are involved and interfere in the testing of photocatalyst behaviour during the degradation of a contaminant. A thorough comparison of photocatalyst activity should include reactions with several different substrates under varied experimental conditions. [Copyright &y& Elsevier]

The technical feasibility and performance of photocatalytic degradation of four water-soluble pesticides (diuron, imidacloprid, formetanate and methomyl) have been studied at pilot scale in two well-defined systems of special interest because natural-solar UV light can be used: heterogeneous photocatalysis with titanium dioxide and homogeneous photocatalysis by photo-Fenton. The pilot plant is made up of compound parabolic collectors (CPCs) specially designed for solar photocatalytic applications. Experimental conditions allowed disappearance of pesticide and degree of mineralisation achieved in the two photocatalytic systems to be compared. In order to assure that the photocatalytic results are consistent, hydrolysis and photolysis tests have been performed with the four pesticides. The initial concentration tested with imidacloprid, formetanate and methomyl was 50 and 30 mg/l with diuron, and the catalyst concentrations were 200 mg/l and 0.05 mM with TiO2 and iron, respectively. Total disappearance of the parent compounds and 90% mineralisation have been attained with all pesticides tested, methomyl being the most difficult to be degraded with both treatments. First-order rate constants, initial rate, time necessary for mineralising 90% of the initial TOC and hydrogen peroxide consumption were calculated in all cases, enabling comparison both of treatments and of the selected pesticide reactivity. [Copyright &y& Elsevier]

Presents the design, set-up and preliminary results of the first European industrial solar detoxification treatment plant. Water treatment technology based on compound parabolic collectors, solar collectors and photocatalysis; Cyanide; Dichloroacetic acid; Solar photocatalysis; Titanium dioxide.

The photodegradation of isoproturon (IP) was performed using TiO2 supported on glass rings in a 1.5 l coaxial rector. After 60 min of phototreatment, IP was completely eliminated and about 80% of dissolved organic carbon (DOC) remained in solution. This efficiency of photodegradation was compared with that using the suspended catalyst in solution and the results indicated that the catalytic activity of TiO2 is not reduced when it is immobilized. The durability of the supported TiO2 was also tested. It was found that after 300 h of photodegradation experiments, its activity was not affected. The chemical nature of the phototreated solution was assessed following the evolution of the initial compound, the organic carbon, and the formed ions, as well as the toxicity and the biodegradability. These analyses demonstrated that the solution resulting from the phototreatment of IP is biologically compatible and its complete mineralization can be performed by biological means. In this way, for the mineralization of an IP solution, a combined photochemical and biological flow reactor was used operating in semi-continuous mode at laboratory scale. This coupled system employs TiO2 supported on glass rings in the photocatalytic reactor and bacteria supported on biolite in the biological part. In this combined system, 100% of the initial concentration of IP and 95% of DOC were removed. Finally, some field experiments under direct sunlight were carried out at the Plataforma Solar de Almerı´a (PSA), Spain. The photocatalytic oxidation of IP was performed in homogeneous and heterogeneous solutions and two different reactors were compared: a medium concentrating radiation system (Helioman, HM) and a non-concentrating radiation system (compound parabolic collectors, CPC). The degradation rates obtained in the CPC are around 5 times more efficient than the HM collectors. However, in both systems 100% of the initial concentration of IP was removed. The possibility of coupling a CPC photoreactor with a biological system at field pilot scale employing supported TiO2 and fixed bacteria for the treatment of real bio-recalcitrant wastewater is also suggested. [Copyright &y& Elsevier]

Examines the degradation of imidacloripid in water by photo-fenton and titanium dioxide photocatalysis at a solar pilot plant. Sources of pesticide water pollution; Kinetics and mineralization of imidacloprid; Percentage of mineralization following photocatalytic treatment.

Studies the photocatalytic oxidation of the non-biodegradable p-nitrotoluene-o-sulfonic acid in homogeneous and heterogeneous solutions at a pilot-scale under solar irradiation. Medium concentrating radiation system; Non-concentrating radiation system (CPC); Chemical and biological analysis; Comparison between Heliomans and CPC reactors.

Presents a study which developed a commercially competitive solar water treatment technology based on compound parabolic collectors. Information on the solar photocatalytic detoxification process; Project objectives; Details on the ultraviolet-reflective surface; Toxicity assessment after photocatalytic treatment.

The main goal of the present study was to explore photocatalytic performance of the TiO 2 –CuO mixture, for solar to hydrogen conversion at pilot plant scale under two different irradiation conditions (sunny and partly cloudy), focusing on high-temperature pretreatment of the catalyst mixture to try to improve TiO 2 doping with copper. P25–TiO 2 and commercial CuO were used with different amounts of Cu (2 wt% or 7 wt% Cu) calcined at 200–400 °C during several hours. Catalysts were tested at pilot plant scale using solar compound parabolic collectors, with glycerol as the sacrificial agent. The photocatalyst prepared after heating at 200 °C for 3 h and with 7 wt% Cu, resulted in higher hydrogen production than under the other heating conditions, and results were slightly better (5–10%) than the reference values with the untreated catalysts. Photocatalytic efficiency was slightly lower at the higher calcination temperature (400 °C). CO 2 production and formation of formate and glycolate clearly demonstrated glycerol photoreforming. The Cu from the calcined catalyst remaining on the solid was significantly less (2.5%) than on the non-calcined catalyst (4.2%), with an important fraction of lixiviated copper and copper deposition on the reactor walls. This is a critical drawback that must be considered for large-scale applications. [Display omitted] • Photocatalytic performance of TiO2–CuO mixture under sunny and cloudy conditions. • TiO2 and CuO with different amounts of Cu calcined at 200–400 °C. • Heating at 200 °C for 3 h (7 wt% Cu) better than untreated catalysts. • Cu lixiviation and deposition on reactor walls hinders long reactions. [ABSTRACT FROM AUTHOR]

• Fe3+-EDDHA/H 2 O 2 for wastewater disinfection has been proved under natural sunlight. • Fe3+-EDDHA promotes bacterial inactivation more than photo-Fenton at neutral pH. • Best bacterial inactivation kinetic rate was obtained with 2.5/5 mg L−1 of Fe3+-EDDHA/H 2 O 2. • An inactivation mechanism based on Fe3+-EDDHA interactions with cell-wall has been proposed. In this study, the use of a commercial iron fertilizer (Fe3+-EDDHA) employed to remediate iron chlorosis in agriculture has been investigated as a promoting bactericidal agent in solar wastewater disinfection processes. Two water matrices: isotonic water (IW) and synthetic fresh-cut wastewater (SFCWW) and two bacterial strains (E. coli O157:H7 and Salmonella enteritidis) have been investigated. The bacterial inactivation rates were compared with other solar processes (solar only, H 2 O 2 /solar, Fe3+/solar and Fe3+/H 2 O 2 /solar) at neutral pH and at laboratory scale (200 mL) under natural solar radiation. Reagents concentration tested was 0.5, 2.5 and 5 mg L−1 of Fe3+ or Fe3+-EDDHA and 1, 5 and 10 mg L-1 of H 2 O 2. Microbial inactivation kinetics showed an improvement of the solar disinfection efficiency when using Fe3+-EDDHA/solar in comparison with Fe3+/H 2 O 2 /solar (conventional photo-Fenton) in both water matrices. Among all reagent concentrations tested, the best inactivation kinetic rate for both bacteria was obtained with 2.5/5 mg L−1 Fe3+-EDDHA/H 2 O 2 , reaching > 5-log reduction in 45 min of treatment or 31 Whm-2 of solar UVA-dose. In addition, an inactivation mechanism has been proposed based on changes in membrane permeability when Fe3+-EDDHA is present and on structural damages caused by hydroxyl radicals (HO•) for Fe3+-EDDHA/H 2 O 2 /solar process. Finally, this study highlights the possibility of efficient fresh-cut wastewater treat for further irrigation reuse in arid and semiarid regions using disinfected wastewater that already includes iron fertilizer, reducing water scarcity and with the additional advantage of diminished impact of iron chlorosis in crops. [ABSTRACT FROM AUTHOR]

To run the photo-Fenton process at circumneutral pH as a tertiary wastewater treatment, the use of chelating agents, such as ethylenediamine disuccinic acid (EDDS), has been proposed. For the design and optimization of photocatalytic reactors, the concept of volumetric rate of photon absorption (VRPA) is very useful, since it combines the effects of light absorption and reactor geometry. This research is focused on the study of the effect of VRPA of the Fe 3+ -EDDS complex on the kinetics of micropollutant removal by solar photo-Fenton at neutral pH. To this end, experiments were carried out at different values of VRPA, from 383 to 1933 µE m −3 s −1 , using the pesticide acetamiprid (ACTM) as a model pollutant at an initial concentration of 100 µg L −1 . Despite instability of the complex with light, high removal percentages were achieved for short reaction times with 0.1 mM Fe 3+ -EDDS. Due to the higher absorptivity of the complexed iron, the process became photosaturated at higher values of VRPA than those reported at pH 2.8 for Fe 3+ allowing to work under photolimitation conditions at shorter optical path lengths than at acidic pH. The higher absorptivity of the complexed iron at neutral pH than Fe 3+ at pH 2.8 allowed to work under photolimitation conditions at shorter optical path lengths because the process became photosaturated at higher values of VRPA. Nonetheless, a 50% increase in the treatment capacity was achieved by increasing the liquid depth by three times. As far as the authors know, this is the first work that quantitatively describes the effect of the radiation and the optical path length on micropollutant removal with Fe 3+ -EDDS. [ABSTRACT FROM AUTHOR]

Glycerol is a by-product in biodiesel production (in the range of g·L−1), so its photoreforming by photocatalysis is a way of valorising it. TiO 2 in photocatalysis has been widely studied, although its efficiency is limited by the high energy band gap, and the electron-hole recombination. Its combination with different semiconductors should improve charge separation, extending also the absorption from UV to visible light. Cu and Ni oxides are two of the most efficient low-cost transition metal oxide catalysts. Experiments were carried out in a 25 L pilot plant connected to a compound parabolic solar collector. Different combinations of the three semiconductors, based on the concentration of each metal on TiO 2 (Me, 5%, 7.2% and 10%) were evaluated. Evonik P25-TiO 2 , CuO and NiO were combined by mechanical mixing. Hydrogen was quantified by a micro gas chromatograph, and copper and nickel leaching by ICP-MS. The best hydrogen production (0.060 mMol kJ−1) was attained with a proportion of 10:1 of TiO 2 :MeO, that corresponds to a total metal concentration of 7.2 wt%, being Cu and Ni in the same proportion. Metal content in solution increased as the reaction progressed, but Ni lixiviation of <0.012 mg L−1 was not significant. Significant Cu leaching (>1 mg L−1) was observed. This article presents novel results, in a solar pilot plant, for determining which ternary mixture can give better results, as well as metal leaching into water. Handling relevant volume of water in anoxic conditions can help to understand the application of this technology for the production of hydrogen. [Display omitted] • Photocatalytic H 2 generation with simultaneous glycerol photoreforming. • Photocatalytic evaluation of a physical CuO:NiO:TiO 2 mixture. • Maximum H 2 production with a total metal content of 7.2%. • Metal content in solution increased as the reaction progressed. [ABSTRACT FROM AUTHOR]

Interest has grown in the modification of titanium dioxide with graphene to improve the photocatalytic behaviour. In this work, titanium dioxide–reduced graphene oxide (TiO 2 –RGO) composites were synthesised by the photocatalytic reduction of exfoliated graphene oxide (GO) by TiO 2 (Evonik P25) under UV irradiation in the presence of methanol as a hole acceptor. The composite materials were characterised using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman and XPS analysis provided evidence that GO was converted to RGO by photocatalytic reduction. The TiO 2 –RGO composites were compared to TiO 2 in suspension reactors for the disinfection of water contaminated with Escherichia coli and Fusarium solani spores under real sunlight. Very rapid water disinfection was observed with both E. coli and F. solani spores. An enhancement in the rate of inactivation of E. coli was observed with the TiO 2 –RGO composite compared to P25 alone. The rate of inactivation of F. solani spores was similar for both the TiO 2 –RGO and P25. When the major part of the solar UVA was cut-off ( λ > 380 nm) using a methacrylate screen, there was a marked increase in the time required for inactivation of E. coli with P25 but no change in the inactivation rate for the TiO 2 –RGO. There is evidence of singlet oxygen production with visible light excitation of the TiO 2 –RGO composites which would lead to E. coli inactivation. [ABSTRACT FROM AUTHOR]

[Display omitted] • TiO 2 -rGO at the solar assisted photodegradation of complex mixing of pesticides. • Best photocatalytic performances with oxygen, regardless of the water matrix. • H 2 O 2 has not improved the final photocatalytic efficiency in any case. • P25-rGO promoted the photo-oxidation of the complex pesticides mix studied. • HBK-rGO presented excellent solar photoefficiency with 200 μg L-1 of pesticides. New titania-reduced graphene oxide (TiO 2 -rGO) nanocomposites have been studied to assess their application in the solar assisted photodegradation of a complex mixing of pesticides (pyrimethanil, isoproturon, alachlor and methomyl) at solar pilot plant, opening the opportunity to extend the use of these hybrid photocatalysts to complex wastewater effluents. TiO 2 -rGO nanocomposites were prepared by hydrothermal method from two commercial TiO 2 , Hombikat UV-100 (HBK) and Aeroxide® P25 (P25). The effect of two different water matrices (simulated and natural) on TiO 2 -rGO solar photoefficiency with two pesticides concentrations (5 mg·L−1 and 200 μg·L−1), and the additional use of an electron scavenging as oxidant agent, such as hydrogen peroxide in a comparison with oxygen from air, has been studied in compound parabolic collectors (CPC) photoreactors. Best photocatalytic performances were always found with oxygen over both TiO 2 -rGO nanocomposites, regardless of the water matrix employed. The use of H 2 O 2 as oxidant agent has not improved the final photocatalytic efficiency in any case. The generation of secondary highly reactive species in the reaction media from reaction of SO 4 ●- /HO radicals, and the more negatively surface charge with low S BET of P25-rGO nanocomposite, besides its lower hydrodynamic size with lower particle aggregation in the reaction conditions, have been responsible to promote the photo-oxidation of the complex pesticides mix studied. Finally, HBK TiO 2 -reduced graphene oxide (HBK-rGO) nanocomposite has presented excellent solar photoefficiency in the photodegradation of 200 μg·L−1 of each pesticide with the oxygen form air, especially under natural water matrix, because of its large negatively charge surface area where probably recombination of electrons and holes is prevented. [ABSTRACT FROM AUTHOR]

Abstract: The degradation of 15 emerging contaminants (ECs) at low concentrations in simulated and real effluent of municipal wastewater treatment plant with photo-Fenton at unchanged pH and Fe=5mgL−1 in a pilot-scale solar CPC reactor was studied. The degradation of those 15 compounds (Acetaminophen, Antipyrine, Atrazine, Caffeine, Carbamazepine, Diclofenac, Flumequine, Hydroxybiphenyl, Ibuprofen, Isoproturon, Ketorolac, Ofloxacin, Progesterone, Sulfamethoxazole and Triclosan), each with an initial concentration of 100μgL−1, was found to depend on the presence of CO3 2− and HCO3 − (hydroxyl radicals scavengers) and on the type of water (simulated water, simulated effluent wastewater and real effluent wastewater), but is relatively independent of pH, the type of acid used for release of hydroxyl radicals scavengers and the initial H2O2 concentration used. Toxicity tests with Vibrio fisheri showed that degradation of the compounds in real effluent wastewater led to toxicity increase. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to propose a municipal wastewater treatment method based on solar Advanced Oxidation Processes (AOPs) permitting reuse of the treated wastewater. Experiments were performed in a pilot compound parabolic collector (CPC) solar plant at the Plataforma Solar de Almería. Mineralisation was monitored by measuring the dissolved organic carbon (DOC), and the concentration profile of each compound during degradation was determined by HPLC–UV. Two different approaches, photo-Fenton (pH=2.8) and TiO2 were tested with 9 different emerging contaminants at 100μgL−1 each (acetaminophen, antipyrine, atrazine, caffeine, diclofenac, isoproturon, progesterone, sulfamethoxazole, and triclosan) at low iron and TiO2 concentrations. Photo-Fenton was by far more effective than TiO2 for degrading these contaminants, and was therefore selected for further study. The 9 contaminants were tested under the following conditions without pH adjustment: (i) Fe=5mgL−1, D.I. water; (ii) Fe=5, 15 and 55mgL−1, standard fresh water; (iii) Fe=5mgL−1, standard fresh water without NaHCO3. Initial amount of hydrogen peroxide was 50mgL−1, frequently analysed and added to maintain this concentration. It was demonstrated that low efficiency in some cases is mainly due to bicarbonates, and it is therefore proposed that the process be improved, either by increasing the iron concentration, or eliminating bicarbonates. [Copyright &y& Elsevier]

The application of electrochemical processes for wastewater treatment has increase significantly in the last two decades. However, most of the works are focused on lab-scale systems testing in saline simulated solutions spiked with a reference organic compound, evidencing the scarcity of studies on actual wastewaters through a more realistic practical approach. The aim of the present work is assessing the performance of electrochemical treatments in actual matrices, considering the formation of different oxidants species, apart from hydroxyl radicals, from dissolved ions contained in target effluents as well as both, the regeneration of Fe2+ and their combination with a light irradiation source. The degradation of a mix of microcontaminants in water matrices with different complexity by solar photoelectron-Fenton at natural pH and at pilot scale has been carried out at Plataforma Solar de Almería. Higher degradation rates were obtained when focusing on the more complex and saline matrices. In addition, complex industrial wastewaters mineralization was also studied by means of solar assisted electro-oxidation, showing the crucial role of ammonium concentration in the effluent, since it acts as a competitor for active chlorine species and so reducing the mineralization rate. • Application studies of electrochemical treatments to actual wastewaters are still very scarce. • Solar energy/electrochemical processes mean an increase in the oxidizing species generated. • Higher micro-contaminant degradation rates achieved by SPEF in actual effluents. • Ammonia in the effluent competes with the DOC for chlorine oxidant species. [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMW), a highly polluted wastewater from the olive oil industry, was treated by solar photocatalysis and solar photo-Fenton. Among the tested systems the application of titanium dioxide alone was not successful. The addition of peroxydisulphate as an electron acceptor had only limited effect on degradation performance and led to high salt concentrations (30 g/l sulphate generated) and a pH value near zero. The photo-Fenton method successfully removed up to 85% COD and up to 100% of phenol index of OMW with different initial concentrations and from different sources. Two solar photocatalytic pilot-plant reactors were used; one of conventional CPC type and an open non-concentrating Falling Film Reactor. The latter, newly designed reactor worked properly and yielded comparable results to the CPC in terms of degradation rate referred to incident UV radiation energy per solution volume. The suspended solids in the OMW hinder light from entering the reactor. Therefore, flocculation induced by a commercial flocculation agent was successfully applied to remove suspended solids. Application of this pre-treatment led to considerable increase of degradation rates and decrease of hydrogen peroxide consumption. [Copyright &y& Elsevier]

The photocatalytic organic content reduction of a selected synthetic municipal wastewater by the use of heterogeneous and homogeneous photocatalytic methods under solar irradiation has been studied at a pilot-plant scale at the Plataforma Solar de Almeria. In the case of heterogeneous photocatalysis the effect of catalysts and oxidants concentration on the decomposition degree of the wastewater was examined. By an accumulation energy of 50 kJ L−1 the synergetic effect of 0.2 g L−1 TiO2 P-25 with hydrogen peroxide (H2O2) and Na2S2O8 leads to a 55% and 73% reduction of the initial organic carbon content, respectively. The photo-fenton process appears to be more efficient for this type of wastewater in comparison to the TiO2/oxidant system. An accumulation energy of 20 kJ L−1 leads to 80% reduction of the organic content. The presence of oxalate in the Fe3+/H2O2 system leads to an additional improvement of the photocatalytic efficiency. [Copyright &y& Elsevier]

TiO2-catalyst suspensions work efficiently in photocatalysis for wastewater treatment. Nevertheless, once photocatalysis is complete, separation of the catalyst from solution becomes the main problem. Catalyst recovery has been enhanced through charge neutralisation and coagulation with electrolytes at lab and pilot-plant scale (40 L) to evaluate the potential for its separation after photocatalytic degradation of pollutants. Zeta-potential analysis showed that the isoelectric point (IEP) of TiO2 suspensions is near pH 7. Settling rates and hydrodynamic diameter of TiO2 particles are maximum at the IEP. However, suspensions are stable at different pH. TiO2 was reused in solar photocatalysis pilot-plant (40 L) for treatment of tetrachloroethylene (C2Cl4) comparing two procedures: reuse of the entire suspension after destruction of the organics without separation of the catalyst, and reuse of the catalyst after it had settled to the bottom and clear water had been removed. Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation, whereas, when TiO2 is separated, the photocatalyst is not deactivated. [Copyright &y& Elsevier]

Industrial wastewaters characterized by its high content in organics and conductivity entails a challenge for conventional treatments due to its low biodegradability. Electro-oxidative processes have been successfully applied for the treatment of this kind of wastewaters achieving high organics and ammonia removal. The degradation process is executed mainly by electrochemically generated active chlorine species, as HClO and ClO− with E0 = 1.49 V; and E0 = 0.89 V, respectively. Under solar radiation, specifically at 313 nm, the formation of Cl (E0 = 2.4 V) from ClO− is promoted, improving the oxidizing capacity of the process. In this work the combination of an electrochemical device with a solar photo-reactor has been evaluated aiming to increase the degradation rate per kWh−1. Two different complex industrial wastewaters were tested, achieving higher organics degradation when electrochemical treatment was assisted by solar light. Toxicity reduction was also assessed and biodegradability enhanced and allowing its ulterior lower-cost biological treatment. Unlabelled Image • Solar-assisted electro-oxidative treatment enhanced wastewater biodegradability. • Solar light promotes the formation of chlorine radicals from electrogenerated chlorine species. • Combination of solar and electrochemical processes achieved substantial organic removal. • Electro-oxidation is effective for removal of nitrogenated compounds. [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]

The efficiency of solar photo-Fenton treatment is related to ambient conditions, as it depends on solar irradiance levels and operation temperature, consequently, it is highly influenced by plant location. In this context, solar photo-Fenton feasibility in three Sunbelt cities (Tabernas -Spain-, Arica -Chile- and Doha -Qatar-) for the treatment of industrial wastewater has been analysed. Process performance was simulated by means of a semi-empirical photo-Fenton model comparing the results obtained with yearly average ambient conditions and the most unfavourable monthly ambient conditions. This data was used with scaling-up purposes in order to determine the photoreactor size and reservoir tank volume needed for each case. Finally, an economical assessment was carried out. Doha presented the lowest total costs (TC), 2.23 €/m3, followed by Arica with 2.45 €/m3 and Tabernas with 2.67 €/m3 for the method based on yearly averages. For the most unfavourable ambient conditions method, the TCs were slightly higher resulting in 2.29, 2.55 and 3.11 €/m3, respectively. Cost breakdowns were analogous independently of scaling-up method and location, being amortization costs (ACs) more influenced by location than operation costs (OCs). Image 1 • Photo-Fenton has been simulated in different locations (model inputs: UV-A and T). • Two different plant scaling-up strategies have been analysed through treatment cost. • Lowest cost found for Doha followed by Arica and Tabernas (2.23, 1.45 and 2.67 €/m3, respectively). • Higher cost where ambient T changes drastically between summer and winter. • Total costs more influenced by amortization costs (≈60%) than by operation costs (≈40%). [ABSTRACT FROM AUTHOR]

This paper contains a multidisciplinary approach that will contribute to design and properly evaluate a treatment line for complex biorecalcitrant wastewaters. To demonstrate this approach a specific industrial wastewater (cork boiling wastewater, CBW) was used. A treatment line based on a coagulation-flocculation step followed by an Advanced Oxidation Process (AOP) (solar photo-Fenton) and combined with an aerobic biological system was evaluated. Applied microbiological techniques: optical microscopy, plate count, DNA extraction and qPCR, indicated that some communities disappeared after the activated sludge adaptation period to the partially treated wastewater, while communities that did not disappear were damaged: 2-log reduction of total heterotrophic bacteria (THB) and a decrease in DNA concentration from 200 ng/μL to 65 ng/μL were observed. Therefore, chemical and microbiological results obtained along the set of experiments, suggested the inefficiency of the combined treatment option between solar photo-Fenton and advanced aerobic biological systems for CBW. This led to the necessity of applying solar photo-Fenton without combining with biotreatment and with the objective of improving the effluent quality enough for being reused in the own industry. Toxicity tests, based on different organisms (after coagulation-flocculation followed by solar photo-Fenton), showed increase on acute toxicity (from 46% to 71% by respirometric assays) and the development of chronic toxicity (from 21–29% to 83–90% also measured by respirometric assays), made evident the incompatibility of this type of wastewater with a biological treatment even after the application of an AOP. Unlabelled Image • Combination of coagulation-flocculation/solar photo-Fenton/aerobic bio-treatment was not successful. • Advanced microbiological analysis showed breakage on specific species after 6 days. • DNA concentration analysis clearly indicated the biotreatment non-feasibility. • Chronic toxicity was generated after partial oxidation of cork boiling wastewater. [ABSTRACT FROM AUTHOR]

• Antipyrine, caffeine, carbamazepine, ciprofloxacin and sulfamethoxazol were completely degraded. • Solar/Fe/H 2 O 2 and solar/Fe/S 2 O 8 2− system mediated by EDDS have been compared. • Different Fe:EDDS ratios, initial iron species and oxidant agents have been tested. • Best ratio for solar/Fe:EDDS/H 2 O 2 was 1:2 and 1:1 for solar/Fe:EDDS/S 2 O 8 2−. The main purpose of this pilot plant study was to compare degradation of five microcontaminants (MCs) (antipyrine, carbamazepine, caffeine, ciprofloxacin and sulfamethoxazole at 100 μg/L) by solar photo-Fenton mediated by EDDS and solar/Fe:EDDS/S 2 O 8 2−. The effects of the Fe:EDDS ratio (1:1 and 1:2), initial iron species (Fe(II) or Fe(III) at 0.1 mM) and oxidizing agent (S 2 O 8 2− or H 2 O 2 at 0.25–1.5 mM) were evaluated. The higher the S 2 O 8 2− concentration, the faster MC degradation was, with S 2 O 8 2− consumption always below 0.6 mM and similar degradation rates with Fe(II) and Fe(III). Under the best conditions (Fe 0.1 mM, Fe:EDDS 1:1, S 2 O 8 2− 1 mM) antipyrine, carbamazepine, caffeine, ciprofloxacin and sulfamethoxazole at 100 μg/L where 90% eliminated applying a solar energy of 2 kJ/L (13 min at 30 W/m2 solar radiation <400 nm). Therefore, S 2 O 8 2− promotes lower consumption of EDDS as Fe:EDDS 1:1 was better than Fe:EDDS 1:2. In photo-Fenton-like processes at circumneutral pH, EDDS with S 2 O 8 2- is an alternative to H 2 O 2 as an oxidizing agent. [ABSTRACT FROM AUTHOR]

• Solar photo-Fenton treatment of artificial sweetener saccharin (SAC) was studied. • Olive mill wastewater (OMW) and EDDS were used for iron complexing at natural pH. • Photo-Fenton (pH 2.8) removed saccharin, intermediates and chronic toxicity. • OMW and EDDS formed iron complexes catalysing H 2 O 2 decomposition and degraded SAC. • Wastewater from natural products processing may be used as iron chelator. The aim of this work was to investigate the treatment of the artificial sweetener saccharin (SAC) in a solar compound parabolic collector pilot plant by means of the photo-Fenton process at pH 2.8. Olive mill wastewater (OMW) was used as iron chelating agent to avoid acidification of water at pH 2.8. For comparative purposes, Ethylenediamine- N , N -disuccinic acid (EDDS), a well-studied iron chelator, was also employed at circumneutral pH. Degradation products formed along treatment were identified by LC-QTOF-MS analysis. Their degradation was associated with toxicity removal, evaluated by monitoring changes in the bioluminescence of Vibrio fischeri bacteria. Results showed that conventional photo-Fenton at pH 2.8 could easily degrade SAC and its intermediates yielding k , apparent reaction rate constant, in the range of 0.64–0.82 L kJ−1, as well as, eliminate effluent's chronic toxicity. Both OMW and EDDS formed iron-complexes able to catalyse H 2 O 2 decomposition and generate HO. OMW yielded lower SAC oxidation rates (k = 0.05–0.1 L kJ−1) than EDDS (k = 2.21–7.88 L kJ−1) possibly due to its higher TOC contribution. However, the degradation rates were improved (k = 0.13 L kJ−1) by increasing OMW dilution in the reactant mixture. All in all, encouraging results were obtained by using OMW as iron chelating agent, thus rendering this approach promising towards the increase of process sustainability. [ABSTRACT FROM AUTHOR]

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]

Graphical abstract Highlights • Very diluted Olive Mill Wastewater could be used as a natural chelating agent. • Iron (5 mg/L) is kept in solution at circumneutral pH by natural polyphenols. • Solar photo-Fenton using natural chelates could treat microcontaminants. Abstract The potential of polyphenols, present in olive mill wastewater (OMW), to act as iron chelators in photo-Fenton reaction without water acidification for the treatment of different microcontaminants in water has been studied. OMW containing 6.3 g/L of phenols has been dosed from 1:100 to 1:1500 in water containing 200 μg/L of terbutryn, chlorfenvinphos, pentachlorophenol and diclofenac. Experiments were performed in compound parabolic collector (CPC) solar pilot plant installed in Plataforma Solar de Almería using Fe 0.1 mM and H 2 O 2 50 mg L−1. The total irradiated area was 3.08 m2 and the total volume 39 L. Results indicated that iron was forming a stable complex with components of OMW along different pH values. > 90% degradation of the four microcontaminants was achieved with solar photo-Fenton at circumnetutral pH adding OMW 1:1200 for keeping iron in solution, allowing to operate a photo-Fenton process without acidifying wastewater. It leads to an alternative to using artificial-synthetic iron-complexing ligands. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The photodegradation of four micro-contaminants has been studied. • Hybrid magnetic materials have been employed in photo-Fenton like process. • TiO 2 homemade shown better performances than P25. • Micro-contaminants degradation has been attained under solar irradiation. Abstract This work reports on the light-induced heterogeneous photodegradation of four micro-contaminants (MCs): Carbamazepine (C), Flumequine (F), Ibuprofen (I), and Sulfamethoxazole (S), using two different heterogeneous advanced oxidation processes. The first one is the semiconductor photocatalysis, run in the presence of the suspension of a home prepared TiO 2 (TiO 2 HP); the second one is an heterogeneous photo-Fenton process run in the presence of a hybrid magnetic nanomaterial (MB3) with an iron oxides core and an organic shell made of bio-based substances (BBS) isolated from urban biowaste. The two materials work upon two different mechanisms and were already tested (and the action mechanism hypothesized) at the lab scale under model conditions: TiO 2 acts as photocatalyst through the photo-generation of hole/electron pairs able to give rise to oxidation and reduction reactions, whereas hybrid magnetic nanomaterial acts in the presence of H 2 O 2 by a photo-Fenton like mechanism. The results evidenced the better performances of TiO 2 HP (also better than the well-known reference TiO 2 P25). Preliminary photodegradation experiments carried out in a pilot plant under natural solar radiation confirmed the good results obtained with TiO 2 HP. Moreover, in the adopted experimental conditions, the Fe(II) leached from MB3 can be considered as responsible of the MCs degradation through a homogeneous photo-Fenton reaction, where MB3 act as iron reservoir. [ABSTRACT FROM AUTHOR]

This paper presents, for first time, a mechanistic model of the solar photo-Fenton process at neutral pH with the Fe 3+ -EDDS complex for micropollutant removal, taking into account irradiance and reactor geometry. Due to its high photon absorptivity, this biodegradable complex allows high percentages of micropollutant removal to be achieved for short reaction times. Nonetheless, no model of the process with the Fe 3+ -EDDS has yet been developed, meaning the proposed mechanism relies on photochemical reactions with the complex previously reported, and hypotheses deduced from experimental observation. The data for acetamiprid (ACTM) removal (100 μg L −1 ) in stirred tank reactors with different liquid depths, under controlled conditions of irradiance and temperature, was used to obtain the model parameters. The model successfully fitted the experimental results obtained outdoors in a raceway pond reactor (RPR), with a change of scale from 0.85 to 19 L. For the calculation of the average volumetric rate of photon absorption (VRPA), the effect of the two components of solar UV radiation (direct and diffuse) as a function of the environmental conditions and the reactor layout was considered. The results showed an important contribution by diffuse radiation, even at noon under spring conditions (≈40% of the total VRPA). In addition, the applicability of the model has been demonstrated in water matrices containing organic matter and HCO 3 −/CO 3 2− ions, usually found in secondary wastewater treatment plant (WWTP) effluents. This approach allows for the development of control and optimization tools for the photo-Fenton process at neutral pH in low-cost photoreactors. [ABSTRACT FROM AUTHOR]

Cork boiling wastewater is a very complex mixture of naturally occurring compounds leached and partially oxidized during the boiling cycles. The effluent generated is recalcitrant and could cause a significant environmental impact. Moreover, if this untreated industrial wastewater enters a municipal wastewater treatment plant it could hamper or reduce the efficiency of most activated sludge degradation processes. Despite the efforts to treat the cork boiling wastewater for reusing purposes, is still not well-known how safe these compounds (original compounds and oxidation by-products) will be. The purpose of this work was to apply an HPLC-high resolution mass spectrometry method and subsequent non-target screening using a multivariate analysis method (PCA), to explore relationships between samples (treatments) and spectral features (masses or compounds) that could indicate changes in formation, degradation or polarity, during coagulation/flocculation (C/F) and photo-Fenton (PhF). Although, most of the signal intensities were reduced after the treatment line, 16 and 4 new peaks were detected to be formed after C/F and PhF processes respectively. The use of this non-target approach showed to be an effective strategy to explore, classify and detect transformation products during the treatment of an unknown complex mixture. [ABSTRACT FROM AUTHOR]

A Cu/TiO 2 photocatalyst has been synthesised by reducing a Cu precursor with NaBH 4 onto the surface of a sulphate pretreated TiO 2 obtained by a sol-gel procedure. The catalyst, that shows a clearly defined anatase phase with high crystallinity and relatively high surface area, and contains Cu 2 O and CuO deposits on its surface, has been used to produce hydrogen in a solar driven pilot plant scale photocatalytic reactor. Different electron donor aqueous solutions (methanol, glycerol, and a real municipal wastewater treatment plant influent) have been tested showing similar or even higher energy efficiency than those obtained using more expensive noble metal based photocatalytic systems. The glycerol solutions have provided the best reactive environments for hydrogen generation. [ABSTRACT FROM AUTHOR]

This study assessed removal of microcontaminants (MCs) from natural water (NW) using iron nanoparticles extracted from olive mill wastewater (ZVI-OMW), an agro-industrial waste product, combined with oxidants under natural solar radiation. The specific effects of corrosion, adsorption and solar photolysis, and of H 2 O 2 , S 2 O 8 2-, carbonates and ZVI-OMW concentrations on treatment efficiency were also evaluated. Lab tests demonstrated that the combination of 1 mM S 2 O 8 2- with NW and 1 mM ZVI-OMW was the best treatment option. Process performance was evaluated under these operating conditions in pilot-scale raceway pond reactors (RPR) at three liquid depths (5, 10 and 15 cm), as well as in a compound parabolic collector (CPC) photo-reactor. The time required to achieve 50% removal of a MC mixture (atrazine, carbendazim, imidacloprid and thiamethoxam, at 100 µg/L each) increased with liquid depth, resulting in 164, 224, and 250 min for 5, 10, and 15 cm, respectively. MC mass removal rate increased with liquid depth, achieving 50% MC removal in the CPC (1 mM ZVI-OMW) in 120 min. Doubling ZVI-OMW concentration was detrimental to process efficiency in both photoreactors due to light obstruction. Partial sedimentation of ZVI-OMW in the RPR suggests that the use of this type of reactor for heterogeneous photocatalysis could present problems for large-size operation. [Display omitted] • ZVI nanoparticles synthetized from olive mill wastewater were used as iron source. • Process efficiency improved when using S 2 O 8 2- instead of H 2 O 2. • Decreasing carbonate/bicarbonate content was detrimental for process efficiency. • 1 mM was the most adequate ZVI concentration both at lab scale and pilot plant scale. • RPR for this application could present problems for large-size operation. [ABSTRACT FROM AUTHOR]

This study shows solar photo-Fenton combined with nanofiltration (NF) to treat microcontaminants (MCs) in actual MWTP effluents. Photo-Fenton was operated at circumneutral pH using (S,S)-Ethylenediamine-N,N'-disuccinic acid trisodium salt (EDDS) as the iron complexing agent (Fe:EDDS in a molar ratio of 1:2) and compared with classical photo-Fenton at pH3. Starting H2O2 concentration was 50 mg/L and Fe was 0.1 mM or 0.2 mM. MC degradation was over 90% in all cases and 35 different MCs were monitored by Liquid Chromatography-Mass Spectrometry enabling the two processes to be compared under real conditions. NF pretreatment enabled photocatalysis to be run at lower flow rates and with higher starting concentrations reducing the surface area of solar collectors and reagents needed. Acute and chronic toxicity tests were also carried out before and at the end of each treatment evaluated and it seemed clear that MC degradation did not produce intermediates with any significant effect on toxicity. In addition, a detailed economic assessment was also performed. Operating costs were higher at circumneutral pH (0.76 €/m³) with EDDS than with classical photo-Fenton at pH3 (0.48 €/m³). [ABSTRACT FROM AUTHOR]

One of the most important factors affecting the application of advanced oxidation processes (AOPs) at full scale are the high operating costs, especially those associated with the cost of the reagents. Therefore, the optimization of operating parameters, such as a reduction in reagent consumption to achieve the partial or complete decontamination of waters, is crucial in AOP application. The present study is focused on the comparison of solar and UV photo-Fenton technologies (by using H 2 O 2 or S 2 O 8 2− ), for the removal of five micro-contaminants (antipyrine, caffeine, carbamazepine, ciprofloxacin and sulfamethoxazole) from simulated freshwater at very low concentrations (100 ppb each one). In addition, economic assessment of the implementation of UV/H 2 O 2 , UV/S 2 O 8 2− , solar/Fe(II)/H 2 O 2 and solar/Fe(II)/S 2 O 8 2− was also carried out. The total costs obtained were 0.42 €/m 3 for solar/Fe(II)/H 2 O 2 with 50 mg/L of initial H 2 O 2 , 0.72 €/m 3 for solar/Fe(II)/S 2 O 8 2− with 50 mg/L of initial S 2 O 8 2− , 0.43 €/m 3 for UV/H 2 O 2 with 50 mg/L of initial H 2 O 2 , 0.49 €/m 3 for UV/S 2 O 8 2− with 50 mg/L of initial S 2 O 8 2− and 0.61 €/m 3 for UV/S 2 O 8 2− with 25 mg/L of initial S 2 O 8 2− . It was concluded that consumption of reagents and electricity costs coming from lamp operation in the UV process had a significant impact on the total operating cost of both technologies. Furthermore, it must be stressed that solar and UV processes promoted by H 2 O 2 are more cost-effective than when employing S 2 O 8 2− . [ABSTRACT FROM AUTHOR]

The purpose of this work was to study the ozonation of nanofiltration (NF) retentates of real municipal wastewater treatment plant (MWTP) effluents for removal of microcontaminants (MCs) and toxicity. MCs present in these effluents were monitored using LC–MS/MS. Acute and chronic toxicity was addressed with Daphnia magna , Vibrio fischeri and Selenastrum capricornutum . Up to 40 MCs were found, most of them in concentrations over 100 ng/L. 90% degradation of the sum of MCs was the critical point of comparison. When the NF membrane system was applied to MWTP effluents, treatment of NF rejection needed 2.75–4.5 g O 3 /m 3 ,4.5 g O 3 /m 3 , which is less than 50% of the ozone needed for direct treatment of MWTP effluent. Treatment time (lower than 11 min) was not influenced by MCs concentration, at least in the range tested (25–190 μg/L). It has been demonstrated that consumption of ozone increased with organic load and inorganic content of different real effluents. MCs were eliminated by ozonation but acute toxicity (against V. fischeri and D. magna ) increased. Chronic toxicity results were different and contrary in D. magna and S. capricornutum , due to the generation of new transformation products more toxic to D. magna than the parent contaminants. S. capricornutum inhibition percentage decreased in all cases after ozonation treatment. According to these results, before ozonation is implemented in MWTPs for the removal of MCs, the transformation products must first be examined and the treatment time or ozone doses should be extended to complete degradation if necessary. [ABSTRACT FROM AUTHOR]

Some wastewaters from the industrial processing of natural products, such as cork boiling wastewater (CBW), have been known to contain high quantities of polyphenolic compounds that are capable of forming complexes with ferric and ferrous iron and even contributing to the reduction of ferric iron. The aim of this work is to evaluate how some of the major components found in CBW are able to influence the availability and regeneration of iron during the Fenton and photo-Fenton process, opening the way for its reuse. Presence of small quantities of CBW (1:50 related with wastewater to be treated) have been shown to increase availability of iron in natural water up to pH 5 and enhance the degradation of the insecticide Imidacloprid as well as a mixture of contaminants (phenol/methomyl/Imidacloprid) at near-neutral pH. Significant mineralization (>70%) of these compounds was also achieved at pH 5, with any added dissolved organic carbon (DOC) removed concurrently with the contaminants, with similar results to pH3 without CBW. The observed effects of the reused CBW are similar to the ones achieved by the addition of commercial iron-chelating agents such as Ethylenediamine-N,N′-disuccinic acid (EDDS) in photo-Fenton process. [ABSTRACT FROM AUTHOR]

The main goal of the present study was to explore pilot-scale combination of H 2 generation with simultaneous water disinfection or decontamination. Performance of a TiO 2 –CuO mixture for solar-to-hydrogen (STH) conversion was studied, focusing on treatment optimization (catalyst dose, proportion of semiconductors in the mixture and concentration of the sacrificial agent). Experiments were performed in a 25-L compound parabolic collector (2 m2) solar pilot plant specifically designed for photocatalytic hydrogen generation. The best operating conditions were 100 mg L−1 TiO 2 –CuO (10:1) with 0.075 M glycerol as the sacrificial agent. The best STH conversion attained was 0.9%. 25 mg L−1 imidacloprid was completely degraded (over 99%). The synergetic effect of anoxic conditions, TiO 2 :CuO and solar radiation caused a significant reduction (>5 Log) in concentration of E. coli , used as a model waterborne pathogen, in less than 10 min. • Photocatalytic H 2 generation with water disinfection or decontamination. • Selection of TiO 2 –CuO mixture dose and proportion of semiconductors. • Reduction (>5 Log) in E. coli concentration in less than 10 min. • Solar photocatalytic H 2 generation at pilot scale. [ABSTRACT FROM AUTHOR]