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The electrochemical treatment of saline wastewater is prone to the formation of inorganic chlorinated byproducts, being a significant challenge for this technology. In this study, we introduce an electrooxidation system utilizing a self-supporting nitrogen-doped carbon-based cathode embedded in carbon cloth (N@C-CC), designed to generate H₂O₂. This system aims to rapidly neutralize free chlorine produced at the anode, a precursor to inorganic chlorinated byproducts, thereby reducing their formation. Our results demonstrate that using the N@C-CC cathode in saline wastewater treatment yielded considerably lower concentrations of ClO₃⁻ and ClO₄⁻ (0.08 mM and 0.024 mM, respectively), which were only 20.5% and 22.7% of the levels produced using a Pt cathode without H₂O₂ generation. Moreover, the presence of cathodically generated H₂O₂ that quenches free chlorine did not significantly impact the degradation performance of phenol. Electron paramagnetic resonance tests and quenching experiments indicated that 1 O₂ was primarily responsible for phenol removal. Validation with real wastewater demonstrated reductions of 68.6% and 56.3% in ClO 3 - and ClO 4 - concentrations, respectively, while effectively removing other pollutants. This study thus offers a compelling method for mitigating the formation of inorganic chlorinated byproducts during the electrooxidation of saline wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Egg-washing wastewater contains a high concentration of nutrition and organic matter since eggs are broken during the washing and cleaning processes. Moreover, the wastewater contains small amounts of detergents or sanitizing agents. These contaminants may pose environmental challenges when they are not properly managed or treated. The study scrutinizes the efficiency of electrocoagulation (EO) and electrooxidation (EO) approaches for egg-wash wastewater treatment. The response surface methodology was employed to optimize the operational parameters. The removal efficiencies of soluble chemical oxygen demand (sCOD 90%), ammonia (NH 3 –N 91%), nitrate (NO 3 −-N 97%), nitrite (NO 2 −-N 89.3%), total dissolved nitrogen (TDN 91%), and phosphate (90%) were measured under various treatment conditions. The optimum treatment conditions achieved in the combined EC + EO process were pH 6.0, current density 20 mA cm−2, and electrolysis time of 60 min, respectively. Degradation kinetics of the egg-wash pollutants showed a significant reduction in half-life (t 1/2) with EO (after EC-Aluminum) at 15 min, 12 min, 17 min, and 15 min for sCOD, NO 2 −-N. NO 3 −-N, and TDN, respectively. Whereas the half-life of NH 3 –N (18 min) and phosphate (17 min) reduced significantly with the EO (after EC-iron). Al and Fe electrodes coupled with boron-doped diamond were found efficient for pollutant removal. Environmental implication. Egg-wash wastewater has a high protein content and contains nutrients that are essential for living organisms. While these compounds can be valuable for agricultural use by increasing soil phosphate concentration, they can also become an issue if the excess nutrients are not properly managed. The soil has a threshold limit for holding phosphate, and any excess amount may be transported through surface runoff or contaminate groundwater through leachate, potentially affecting aquatic ecosystems and water quality. This study explores the efficiency of electrocoagulation and electrooxidation methods in treating egg-wash wastewater. These methods aim to remove pollutants and reduce their environmental impact. [Display omitted] • Egg-wash wastewater contains a higher concentration of pollutants • High COD, TDN, and phosphate increases the environmental concern • Operational parameters were optimized to achieve better pollutant removal • Pollutant reduction could be effective for the resource recovery of contaminates [ABSTRACT FROM AUTHOR]

Industrial reverse osmosis concentrate (ROC) was electrochemically oxidized using a continuous-flow system (CFS) with a front buffer tank. Multivariate optimization including Plackett-Burman (PBD) and central composite design based on response surface method (CCD-RSM) was implemented to investigate the effects of characteristic (e.g., recirculation ratio (R value), ratio of buffer tank and electrolytic zone (R V value)) and routine (e.g., current density (i), inflow linear velocity (v) and electrode spacing (d)) parameters. R , v values and current density significantly influenced chemical oxygen demand (COD) and NH 4 +−N removal and effluent active chlorine species (ACS) level, while electrode spacing and R V value had negligible effects. High chloride content of industrial ROC facilitated the generation of ACS and subsequent mass transfer, low hydraulic retention time (HRT) of electrolytic cell improved the mass transfer efficiency, and high HRT of buffer tank prolonged the reaction between the pollutants and oxidants. The significance levels of COD removal, energy efficiency, effluent ACS level and toxic byproduct level CCD-RSM models were validated by statistical test results, including higher F value than critical effect value, lower P value than 0.05, low deviation between predicted and observed values, and normal distribution of calculated residuals. The highest pollutant removal was achieved at a high R value, a high current density and a low v value; the highest energy efficiency was achieved at a high R , a low current density and a high v value; the lowest effluent ACS and toxic byproduct levels were achieved at a low R value, a low current density and a high v value. Following the multivariate optimization, the optimum parameters were decided to be v = 1.2 cm h−1, i ≥ 8 mA cm−2, d ≥ 4, R V = 10−20 and R = 1 to achieve better effluent quality (i.e., lower effluent pollutant, ACS and toxic byproduct levels). [Display omitted] • R , v values and current density significantly influenced the performance of CFS-C system. • R V value and electrode gap can be further optimized to reduce the fixed investment. • The CCD-RSM models were more efficient than PBD models in predicting the responses. • Multivariate coordination can optimize the parameters of industrial ROC treatment process. • High inflow load of CFS-C system should be set according to COD removal CCD-RSM model. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of different carbon-based electrodes with and without nanoparticles of platinum electrochemically dispersed on their surface has been studied. Among others, reduced graphene oxide based electrodes was used to determine the best conditions for the decolorization/degradation of the reactive dye C.I. Reactive Orange 4 in sulfuric medium. Firstly, the electrochemical behavior was evaluated by cyclic voltammetry. Secondly, different electrolyses were performed using two cell configurations: cell with anodic and cathodic compartments separated (divided configuration) and without any separation (undivided configuration). The best results were obtained when reduced graphene oxide based anodes were used. The degree of decolorization was monitored by spectroscopic methods and high performance liquid chromatography. It was found that all of them followed pseudo-first order kinetics. When reduced graphene oxide-based electrodes coated with dispersed platinum by alternate current methods electrodes were used, the lowest energy consumption and the higher decolorization kinetics rate were obtained. Scanning Electronic Microscopy was used to observe the morphological surface differences. [ABSTRACT FROM AUTHOR]

Table olive processing wastewater (TOW) is a notoriously polluting due to its high organic and phenol content. To reduce them, an electrochemical process has been studied for the treatment of this effluent. Experiments were performed with a cell equipped with lead dioxide (PbO 2 ) or boron-doped diamond (BDD) as anode and platinum as cathode, where Table Olive Wastewater (TOW) were destroyed by hydroxyl radicals formed at the anode surface from water oxidation. The comparative study of both systems shows the performance of the BDD anode compared to PbO 2 , explained by the large amounts of hydroxyl radicals generated effective at BDD anode and its synthesis characteristics. Using LC/MS analysis, it was possible to determine hydroxytyrosol, as major phenolic compounds, in table olive processing wastewater and its concentration reach 890 mg L −1 . A possible reaction mechanism oxidation for hydroxytyrosol was proposed. The kinetics decays for hydroxytyrosol degradation on PbO 2 anode follows a pseudo-first order reaction with a rate constant 0.9 h −1 for j app value 20 mA cm −2 . [ABSTRACT FROM AUTHOR]

Electrochemical treatment of organic matter for environmental remediation necessitates the development of cheap and robust electrodes that are chemically and structurally stable. To address this challenging requirement, we demonstrate a new electrochemical approach using a simple copper electrode under cathodic conditions to electrochemically generate reactive nitrosonium ions for the degradation of different classes of synthetic organic dyes. This could be achieved in an aqueous HNO 3 /KNO 3 electrolyte at a relatively low cathodic potential of −0.5 V RHE at room temperature. UV–visible absorption spectroscopy, Raman spectroscopy, liquid chromatography – mass spectrometry and total organic carbon measurements revealed the rapid decolorisation and mineralisation of several dye types such as triarylmethane dyes (crystal violet, cresol red), an azo dye (methyl orange) as well as a sulfur containing thiazine dye (toluidine blue). The total organic carbon content of a 50 mg L−1 methyl orange solution was found to decrease by 83% after 1 h of electrolysis. Promisingly, locally sourced river and creek water samples spiked with 50 mg L−1 methyl orange were also successfully treated for up to 6 cycles at a simple Cu electrode, demonstrating potential for the remediation of polluted waterways. [Display omitted] • A new electrochemical approach to degrading organic dyes in water is presented. • The generation of reactive nitrosonium ions at a copper electrode in a nitrate electrolyte is demonstrated. • Three classes of organic dyes could be effectively decolourised and mineralised while nitrate ions are converted to ammonia. • The approach is effective in real water samples. [ABSTRACT FROM AUTHOR]

The effect of the electrochemical treatment (potentiostatic treatment in a filter-press electrochemical cell) on the adsorption capacity of an activated carbon cloth (ACC) was analyzed in relation with the removal of 8-quinolinecarboxylic acid pollutant from water. The adsorption capacity of an ACC is quantitatively improved in the presence of an electric field (electroadsorption process) reaching values of 96% in comparison to 55% in absence of applied potential. In addition, the cathodic treatment results in higher removal efficiencies than the anodic treatment. The enhanced adsorption capacity has been proved to be irreversible, since the removed compound remains adsorbed after switching the applied potential. The kinetics of the adsorption processes is also improved by the presence of an applied potential. [ABSTRACT FROM AUTHOR]

Nowadays, the decrease in useable water resources day by day necessitates studies on the protection of resources by treating wastewater. It is also one of the best options for reusing the water to be treated, and electrochemical technologies can be an alternative to existing technologies, because of the easy operation and effectiveness of pollutants treatment. The study evaluated the treatment of domestic wastewater by Electrocoagulation-Electrooxidation successive processes in continuous and batch modes. The effects of the operational parameters on the Electrocoagulation and Electrooxidation processes were determined for removals of chemical oxygen demand, ammonium-nitrogen, nitrate-nitrogen, turbidity, phosphate-phosphorus, nitrite-nitrogen, and Escherichia coli. The experiments revealed that the Electrocoagulation process effectively removed all pollutants but not ammonium-nitrogen. After the Electrocoagulation process was completed, ammonium-nitrogen from domestic wastewater treatment was removed with the Electrooxidation process for further treatment. The optimum operational conditions in the Electrocoagulation process were electrode type iron anode-carbon felt cathode, current density 100 A m−2, initial pH original, and operation time 20 min. Under these conditions, removal efficiencies of chemical oxygen demand, turbidity, phosphate-phosphorus, nitrate-nitrogen, nitrite-nitrogen, and Escherichia coli were found to be 90.2%, 96%, 88.2%, 73.6%, and 97.9%, respectively. The removal efficiencies for the optimum operating conditions of the Electrooxidation process using Ti/SbO 2 anode and stainless steel cathode were obtained as 95.4% (chemical oxygen demand), 89.4% (ammonium-nitrogen), and 99.99% (Escherichia coli) at 100 A m−2, 5 mm electrode distance, and 30 min operation time. Finally, the EC process is an effective process for removing chemical oxygen demand, phosphate-phosphorus, turbidity, nitrite-nitrogen, and nitrate-nitrogen. However, the Electrooxidation process is a successful process for the treatment of ammonium-nitrogen and Escherichia coli. This research revealed that the sequential processes effectively removed organic, inorganic, and Escherichia coli from domestic wastewater. [Display omitted] • A sequential EC/EOx is an effective process for domestic wastewater treatment. • EC process is used as a pretreatment for COD and PO 4 –P removal. • EC/EOx process was improved both organic, inorganic, and disinfection. • EC/EOx process is more effective for E.coli removal (100%). • The treated domestic wastewater after EC/EOx can be reused for various fields. [ABSTRACT FROM AUTHOR]

Highlights: [•] The efficiency of two methods for landfill leachate purification was investigated. [•] Untreated leachate proved to be both cyto- and genotoxic to human or plant cells. [•] Treated leachate did not cause increase in cyto- and genotoxic damage. [•] Both methods have high removal efficiency and provide toxicological safety. [Copyright &y& Elsevier]

Abstract: An integrated electro-oxidation and electrocoagulation system was designed and used to remove As(III) and F− ions from water simultaneously. Dimensionally stable anodes (DSA), Fe electrodes, and Al electrodes were combined into an electrochemical system. Two pieces of DSA electrodes were assigned as the outside of the Fe and Al electrodes and were directly connected to the power supply as anode and cathode, respectively. The Fe and Al ions were generated by electro-induced process simultaneously. Subsequently, hydroxides of Fe and Al were formed. Arsenic ions are mainly removed by iron hydroxides and F− ions are mainly removed by the Al oxides. At the initial concentration of 1.0mgL−1, most of As(III) was transferred into As(V) within 40min at current density of 4mAcm−2, whereas F− ions can be efficiently removed simultaneously. The effect of the ratio of Fe and Al plate electrodes and current density on the removal of As(III) and F− was investigated. With one piece of Fe plate electrode and three pieces of Al plate electrodes, it is observed that As(III) with concentration of 1mgL−1 and F− with concentration of 4.5mgL−1 can be removed and their final concentrations were below the values of 10μgL−1 and 1.0mgL−1, respectively within 40min. Removal efficiency of As(III) increases with the increase of solution pH. However, in the pH range of 6–7, removal efficiency of F− is the largest. [Copyright &y& Elsevier]

Abstract: Polycyclic aromatic hydrocarbons (PAHs) cause a high environmental impact when released into the environment. The objective of this study was to evaluate the capacity of decontamination of polluted soils with PAHs using the sequence extraction-electrochemical treatment: extraction of PAHs from the soil with surfactant followed by electrochemical degradation of the liquid collected. Several PAHs (anthracene, benzo[a]pyrene, and phenanthrene) have been used as model compounds since such PAHs are found in high concentrations in contaminated environmental samples. Due to their hydrophobic nature, soil extraction has been limited. In this work, the use of six surfactants, Brij 35, Merpol, Tergitol, Tween 20, Tween 80 and Tyloxapol, has been evaluated on the PAH extraction from a model soil such as kaolin. Furthermore, the electrochemical degradation of PAHs with the surfactant that gave the best result was investigated working with neat solutions. The electrochemical treatment of these solutions was carried out in two electrochemical cells with different working volumes, 0.4 and 1.5l, and electrode material (graphite or titanium). Near complete degradation was reached for all the experiments in both cells. [Copyright &y& Elsevier]

Abstract: The investigation presented here focussed on the electrochemical decolourisation of a commercial, textile indigo dye, in an undivided electrochemical cell using graphite electrodes. The decolourisation values obtained employing halide salts—sodium chloride, potassium bromide and potassium iodide—and a reductive agent—sodium meta-bisulphite—as electrolytes are higher than those attained when no electrolyte was used. The highest decolourisation value at a low level of electric power consumption was obtained with sodium chloride. Besides, this electrolyte is usually found in the coloured wastewaters of textile industry. Thus, a detailed study was carried out to determine the influence of electrolyte—sodium chloride—and dye concentration on the efficiency of the process expressed in terms of energy consumption and extension of the decolourisation reaction. The scale-up of the treatment with sodium chloride was satisfactorily tested in a 20l cell. [Copyright &y& Elsevier]

Electrochemical treatment can solve the problems arising due to effluents and offer an effective alternative to the existing methods. An undivided static electrolyser was charged with distillery effluent and the organics were oxidized electrochemically. Anodized graphite plate anodes and graphite cathodes were used for the treatment of distillery effluent. The effect of pH and current density on the treatment was studied. Sodium fluoride, sodium chloride and sodium bromide were chosen as electrolyte and their influence was found out. Complete decolorization has been observed in all cases. A maximum of 93.5% of biological oxygen demand reduction, 85.2% of chemical oxygen demand reduction and 98.0% absorbance reduction were obtained in the presence of sodium chloride as supporting electrolyte. Probable mechanism was also proposed for the oxidation of organics present in the effluent. [Copyright &y& Elsevier]

Conventional wastewater treatment processes cannot effectively remove dissolved organic nitrogen (DON) and soluble non-reactive phosphorus (sNRP), which can pose regulatory compliance challenges for total nitrogen and total phosphorus discharges. Moreover, DON and sNRP are not easily recoverable for beneficial reuse as part of the waste to resource paradigm. Conversion of DON and sNRP to more readily removable dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (sRP), respectively, will help meet stringent nutrient limits and facilitate nutrient recovery. In this study, electro-oxidation (EO) was evaluated for conversion of four DON compounds to DIN and five sNRP compounds to sRP. EO was more efficient and provided higher extents of conversion of the recalcitrant nutrient fractions compared to a more traditional advanced oxidation process, UV/H 2 O 2. Direct electron transfer was likely the dominant oxidation mechanism for EO-based DON and sNRP conversion, with DON being more recalcitrant. Among the DON compounds tested, greater availability of primary amine (C–N bonds) yielded greater conversion compared to compounds with fewer primary amine or those with secondary amine (C–N–C bond). Among the sNRP compounds tested, those with P–O–C bonds (organic sNRP) converted more readily than those with P–O–P bonds (inorganic sNRP), presumably because cleavage of the latter bond requires greater energy. Using 30 min of EO treatment, the highest DON and sNRP compound conversion was 11.7 ± 0.09% for urea and 31.1 ± 0.75% for beta-glycerol phosphate. A similar extent of EO-based conversion of DON (6.41 ± 1.5%) and sNRP (32.7 ± 3.3%) was observed in real wastewater. • Electro-oxidation (EO) converts DON and sNRP more efficiently than UV/H 2 O 2. • sNRP conversion to removable/recoverable P was more efficient than DON conversion. • Organic sNRP was more susceptible to EO-based conversion compared to inorganic sNRP. • Direct electron transfer was likely the dominant mechanism for EO-based conversion. • The wastewater matrix did not significantly inhibit sNRP conversion. [ABSTRACT FROM AUTHOR]

The environmental persistence of hexachlorobenzene (HCB) is a challenge that promotes studies for efficient treatment alternatives to minimize its environmental impact. Here, we evaluated the HCB removal by electrochemical, biological, and combined approaches. The electrochemical treatment of 4 μM HCB solutions was performed using a synthesized Ti/RuO 2 –IrO 2 –TiO 2 anode, while the biological treatment using mangrove-isolated bacteria was at 24, 48, and 72 h. The HCB degradability was assessed by analyzing chemical oxygen demand (COD), microbial growth capacity in media supplemented with HCB as the only carbon source, gas chromatography, and ecotoxicity assay after treatments. The synthesized anode showed a high voltammetric charge and catalytic activity, favoring the HCB biodegradability. All bacterial isolates exhibited the ability to metabolize HCB, especially Bacillus sp. and Micrococcus luteus. The HCB degradation efficiency of the combined electrochemical-biological treatment was evidenced by a high COD removal percentage, the non-HCB detection by gas chromatography, and a decrease in ecotoxicity tested with lettuce seeds. The combination of electrochemical pretreatment with microorganism degradation was efficient to remove HCB, thereby opening up prospects for in situ studies of areas contaminated by this recalcitrant compound. [Display omitted] • Several mangrove bacteria were investigated in the biological treatment of HCB. • An electrochemical pretreatment followed by a subsequent biological treatment is proposed. • Laser-made anode showed enhanced performance in the HCB removal by a coupling process. • The combined treatment removed both HCB and residual toxic substances from the media. [ABSTRACT FROM AUTHOR]

An inadequate and inefficient performance ability of conventional methods to remove persistent organic pollutants urges the need of alternative or complementary advanced wastewater treatments methods to ensure the safer reuse of reclaimed water. Photoelectrochemical methods are emerging as promising options among other advanced oxidation processes because of the higher treatment efficiency achieved due to the synergistic effects of combined photochemical and electrolysis reactions. Synergistic effects of integrated photochemical, electrochemical and photoelectrochemical processes not only increase the hydroxyl radical production; an enhancement on the mineralization ability through various side reactions is also achieved. In this review, fundamental reaction mechanisms of different photoelectrochemical methods including photoelectrocatalysis, photo/solar electro-Fenton, photo anodic oxidation, photoelectroperoxone and photocatalytic fuel cell are discussed. Various integrated photochemical, electrochemical and photoelectrochemical processes and their synergistic effects are elaborated. Different reactor configurations along with the positioning of electrodes, photocatalysts and light source of the individual/combined photoelectrochemical treatment systems are discussed. Modified photoanode and cathode materials used in the photoelectrochemical reactors and their performance ability is presented. Photoelectrochemical treatment of real wastewater such as landfill leachate, oil mill, pharmaceutical, textile, and tannery wastewater are reviewed. Hydrogen production efficiency in the photoelectrochemical process is further elaborated. Cost and energy involved in these processes are briefed, but the applicability of photocatalytic fuel cells to reduce the electrical dependence is also summarised. Finally, the use of photoelectrochemical approaches as an alternative for treating soil washing effluents is currently discussed. • Photoelectrochemical methods, its mechanism and synergistic effects are reviewed. • Real effluents treatment by photoelectrochemical methods are discussed. • Cost and energy analysis are compared. • Photoelectrochemical approaches for treating soil washing effluents are deliberated. [ABSTRACT FROM AUTHOR]

Electrokinetic remediation is a widely admitted technology forrectifying heavy metal-contaminated soil. Various technologies have been effectively developed to improve the metal removal efficiency of contaminated soil by electrochemical treatment alone or in combination with other remediation technologies. The working components for electrokinetic system, such as supplying power for electric fields, installing electrodes to generate electric fields, introducing electrolytes and other potential materials as a reactive medium are crucial. This review focuses on the specific functions of the working components in electrokinetic systems and their effects on the efficiency of heavy metal removal using electrochemical process. The advancements in working components were systematically summarized, such as power for electric fields, electrodes, electrolytes and ion exchange membrane, which have various impacts on the effectiveness of electrokinetic remediation. Additionally, this study introduces the application of dominating technologies at present coupled with electrokinetics. Overall, a judicious design and reasonable operation in the application of electrokinetic-coupled remediation should be implemented to enhance the removal process of heavy metals from contaminated soil. Image 1 • Mechanisms of electric field, electrodes, and electrolytes were discussed. • Advances in electric field, electrodes, and electrolytes were reviewed. • Mechanisms and applicability of using ion exchange membrane were summarized. • Applicability of dominating current technologies coupled with EK was presented. • Future studies on EK remediation were directed for the potential researchers. [ABSTRACT FROM AUTHOR]

In this study, a novel Ti/SnO 2 –Sb anode, improved using a laser heating manufacturing procedure, was applied in wastewater treatment. For comparison purposes, similar anodes were manufactured using the conventional furnace heating procedure. Electrochemical characterizations in the background electrolyte confirmed that the novel material has improved electric conductivity, as compared to the furnace-made one and, hence, it may lead to much lower operating costs in real applications. The electrocatalytic properties of the novel anode in comparison with the conventional were evaluated using a standard and well-known reaction: the phenol oxidation. Different operational conditions were evaluated. Concentrations of phenol were monitored by HPLC and analysis of organic matter by TOC analyzer. The best condition of phenol removal was associated with a relatively low energy consumption of 0.80 kWh (gTOC)−1 and specific electrical energy consumption of 0.81 kWh m−3 order−1. Interestingly, the phenol is not completely removed after 60 min of treatment using the furnace-made anode under the same operating conditions in which was fully depleted with the new electrode. Moreover, chlorinated by-products remained in the final solution with the conventional electrode and were exhausted with the novel one. Finally, after an extensive comparison with literature about the oxidation of phenol, the Ti/SnO 2 –Sb produced by laser-manufacturing procedure presented the best phenol removal as compared with both non-active and active anodes. Image 1 • Novel laser-made Ti/SnO 2 –Sb anode shows outstanding performance for phenol removal. • The chlorinated by-products are entirely removed after 60 min of treatment. • Chloride affects the kinetics of phenol removal highly catalyzing depletion of Phenol. • Outstanding performance of novel anode is observed, especially in the presence of NaCl. [ABSTRACT FROM AUTHOR]

Landfill leachate is challenging to treat due to its complex composition. Advanced oxidation processes such as Fenton process can be effective to treat leachate. Herein, a previously developed membrane electrochemical reactor (MER) was coupled with Fenton oxidation through providing synergistic benefits with the low solution pH, reduced organics, and ammonia removal/recovery. This two-stage coupled system reduced the leachate COD by 88%, much higher than that from the standalone Fenton process treating raw leachate. In addition, the usage of chemical reagents has been greatly reduced. At a dimensionless oxidant dose of 1.0, the coupled MER-Fenton system reduced the consumption of both FeSO 4 ⋅7H 2 O and H 2 O 2 by 39%, H 2 SO 4 by 100%, and NaOH by 55%. Consequently, the sludge production was reduced by 51% in weight and 12% in volume. Despite electricity consumption by the MER, the coupled system cost $4.76 per m3 leachate less than the standalone Fenton treatment. More notably, direct Fenton oxidation removed only 21% of ammonia; in comparison the MER-Fenton system removed ammonia by 98% with the possibility for recovery at a rate of 30.6–55.2 kg N m−3 reactor d−1. Those results demonstrate that coupling MER with Fenton process could mitigate some inherent drawbacks of Fenton oxidation such as ineffective ammonia removal, high acid and chemical reagents dose requirements, and a large amount of sludge generation. This system may be moved towards practical applications by addressing a few challenges such as using renewable energy to power MER. Image 1 • Low pH created by electrochemical oxidation can be used by Fenton process. • Removal of organic compounds in MER has greatly reduced Fenton reagents. • MER-Fenton system achieves significantly more ammonia removal than Fenton alone. • Production of Fenton sludge is significantly reduced. [ABSTRACT FROM AUTHOR]

The resulting solutions from the cotton fabrics dyeing using the trichromy Procion HEXL, with NaCl as electrolyte, were electrochemically treated. These dyes have two azo groups as chromophores and two monochlorotriazinic groups as reactive groups in their structure. The combined oxidation/reduction at 125 mA cm−2 in a filter-press cell without compartment separation was carried out using an anode of Ti/SnO 2 –Sb–Pt and a cathode of stainless steel. This procedure has been effective in previous experiments using sulphate as electrolyte. A significant decrease in total organic carbon (TOC), chemical oxygen demand (COD), and total nitrogen (TN) was obtained. Moreover, the process took place efficiently. The average oxidation state (AOS) and the carbon oxidation state (COS) data confirmed the presence of stable oxidized intermediates in the electrolysed solution. The chromatography and the UV–Visible spectrophotometry assays indicated that full decolourisation is obtained at a loaded charge of around 0.81 Ah L−1 which is associated with an electrical energy per order (EEO) of 1.20 kWh m−3. Image 1087917 • Electrolyses of a real dyestuff wastewater from a trichromy of reactive dyes are done. • Stable Ti/SnO 2 –Sb–Pt anodes in NaCl solutions permit complete decolourisation. • Very low energy consumption is needed in the presence of chloride. • High mineralization of organic matter is obtained with chloride addition. • This treatment is a valuable alternative for textile wastewater remediation. [ABSTRACT FROM AUTHOR]

In this work, the combination of biological and electrochemical processes to mineralize oxyfluorfen has been studied. First, an acclimatized mixed-culture biological treatment was used to degrade the biodegradable fraction of the pesticide, reaching up to 90% removal. After that, the non-biodegraded fraction was oxidised by electrolysis using boron-doped diamond as the anode. The results showed that the electrochemical technique was able to completely mineralize the residual pollutants. The study of the influence of the supporting electrolyte on the electrochemical process showed that the trace mineral solution used in the biological treatment was enough to completely mineralize the oxyfluorfen, resulting in total organic carbon removal rates that were well-fitted by a first-order model with a kinetic constant of 0.91 h−1. However, the first-order degradation rate increased approximately 20% when Na 2 SO 4 was added as supporting electrolyte, reaching a degradation rate of 1.16 h−1 with a power consumption that was approximately 70% lower. • Low oxyfluorfen concentrations were completely removed by means of bioprocesses. • When operating with high oxyfluorfen concentrations product inhibition appeared. • Electrochemical treatment completely removed the non-biodegraded fraction. • Coupling biological and electrochemical processes ensure oxyfluorfen mineralization. • Na2SO4 as supporting electrolyte increased the first order rate in about 20%. [ABSTRACT FROM AUTHOR]