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Effluent wastewater from industrial processes needs to be properly treated before being discharged into the environment. Conventional procedures for handling this wastewater can be problematic due to the presence of toxic elements, time constraints, and complexity. However, a new electrochemical procedure has been developed as an effective method for remediation. In a recent study, refinery wastewater was successfully treated using an electrochemical technique combined with ultrasonic irradiation and photocatalysis. The study found that electrocoagulation, which uses cheap and recyclable metal electrodes, was a simple, efficient, practical, and cost-effective way to handle refinery wastewater. Various parameters were investigated, including electrode metals, operating time, applied voltage, pH, inter-electrode gap, and temperature. The aim was to determine the optimal configuration for pollutant removal. The study also focused on the synergistic effects of combining electrocoagulation and photocatalysis to improve the efficiency of contaminant removal in oily wastewater. By integrating these two treatment technologies, the researchers aimed to enhance pollutant removal rates, energy efficiency, and overall system performance. The research provided valuable insights into the feasibility, optimization parameters, and applicability of the electrocoagulation-photocatalysis process for remediating organic contaminants in oily wastewater industrial effluents. The results showed that electrocoagulation, especially when combined with ultrasonic irradiation and TiO2 photocatalysis, was highly effective in pollutant removal within a short timeframe. These findings support the implementation of this procedure for remediating most industrial wastewater.In conclusion, the study contributes to the development of more effective and sustainable water treatment strategies. The electrocoagulation-photocatalysis process shows promise in addressing the remediation of organic contaminants in oily wastewater from industrial processes. [ABSTRACT FROM AUTHOR]

The present study is based on the application of the electrocoagulation process in removal of Eriochrome Black T dye pollutant. It is found that many factors like voltage, temperature, number of pairs of electrodes, contact time, inter electrode distance are affecting the electrocoagulation. As voltage is increased from 5 V DC to 30 V DC the removal efficiency increases linearly and attained 98.3% at 13 V DC and beyond that the removal of dye is constant. The temperature plays important role in electrocoagulation and maximum removal was observed at 28 °C, at high temperature electrocoagulation decreases. It is also found that inter-electrode distance of 0.5 cm is more favourable for removal. As the number of pair of electrodes increases the removal capacity also increases. If there is a rise in concentration of the solution from 10 ppm to 1000 ppm the efficiency decreases from 99.2% to 63.6%. The chemical oxygen demand of the treated solution drops from 1600 to 320 ppm under 13 V DC, 180 s of contact time for 25 ppm of dye solution. The energy consumption, anode dissolution also plays a crucial role in removal of dye. [ABSTRACT FROM AUTHOR]

Background: Considering the increased demand for cars in different countries during recent years, using car washes for washing vehicles has received a lot of attention. This study aimed to assess removing chemical oxygen demand (COD) from car wash effluent using the electrocoagulation method. Methods: A reactor with dimensions of 40 cm * 50 cm * 50 cm of Plexiglas with a volume of 90 L equipped with an electric current generator and an electrode was used connected to the DC current generator in the form of Al-Al. The response surface method (RSM) was applied to optimize the factors affecting COD removal in the electrocoagulation process. For this purpose, D-optimal was utilized to optimize the experiments. The effects of measurable factors such as electrolysis time (X1), current density (X2), and aeration time (X3) were examined to check COD removal. Results: According to the results, the optimal operating conditions for COD removal during electrolysis (30 min) were as follow: the current density was 18.75 A/m², and the aeration time of 30 min was 48.51%. Conclusion: In conclusion, electrocoagulation is, to some extent, a reliable and environmentally compatible technique for car wash wastewater treatment. [ABSTRACT FROM AUTHOR]

Clean water scarcity and food waste are global environmental concerns. However, food waste contains valuable bioactive compounds along with other ingredients currently get discarded in landfills, contributing to methane emissions, and exacerbating global warming. To address these issues, I developed a solution that utilizes fruit waste as bio-sorbents to purify contaminated water. Twenty-five Fruit Peel Powders (FPPs) were prepared and screened for their adsorption properties using methylene blue dye tests. Based on their effectiveness in removing divalent metal ions, oil waste, microbes, microplastics (PP), and agricultural runoffs, the FPPs were grouped into five categories, with three replicates each. Functional kinetics and dose dependency were examined using Langmuir and Freundlich adsorption isotherms for each category. To optimize the process, FPPbased adsorption chromatography (AC) was combined with electrocoagulation (EC). Statistical response surface methodology, employing a central composite design, was used to optimize the main variables: column temperature, electrolysis time, electrode distance, initial contaminant dose, and column bed contact time. Fifty different combinations of experiments were conducted, encompassing low, high, and axial points, to achieve maximum removal efficiency (R%) for all contaminants. The suitability of the models was verified through ANOVA. Under the optimized conditions, up to 91% of contaminants were successfully removed from the water, enabling a low-cost process with reduced sludge output. [ABSTRACT FROM AUTHOR]

Landfill leachate is commonly heavily contaminated wastewater. and consists of a high number of organic compounds, inorganic salts, toxic gases and heavy metals that exert a serious threat to the environment and public health. Thus, it requires treatments before direct release into receiving waters. This paper presents the results of electrocoagulation (EC) and chemical coagulation (CC) treatment of leachate from the Erbil landfill site. The removal efficiency of chemical oxygen demand (COD), phosphate (PO43-), total suspended solids (TSS), total organic compound (TOC), and color of leachate was studied using iron and aluminum electrodes. The removal percentages were also compared to those produced by electrochemically generated Fe2+ and Al3+ dosages. The effect of different pH values on the removal efficiency of these parameters was evaluated at optimal conditions. The removal percentages for chemically added coagulants were lower than those for electrochemically generated Fe2+ and Al3+. In EC, the highest COD removal efficiency of 92% and 87% was achieved at the original concentration (C1) for iron and aluminum electrodes, respectively. The iron and aluminum electrodes also showed a maximum color removal of 90% and 95%, respectively, for the original undiluted leachate solution. Both Fe and Al electrocoagulation methods were not effective in removing TOC from the leachate of municipal solid waste. The highest removal efficiency of 78% was achieved at a 1:4 diluted solution (C2) using the Al-electrocoagulation method. The maximum removal percentage for PO43-was 94% at C1 using the Fe-electrocoagulation system. However, both systems were not very effective in removing TSS. [ABSTRACT FROM AUTHOR]

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This paper investigated the treatment of textile wastewater polluted with aniline blue (AB) by electrocoagulation process using stainless steel mesh electrodes with a horizontal arrangement. The experimental design involved the application of the response surface methodology (RSM) to find the mathematical model, by adjusting the current density (4-20 mA/cm2), distance between electrodes (0.5-3 cm), salt concentration (50-600 mg/l), initial dye concentration (50-250 mg/l), pH value (2-12 ) and experimental time (5-20 min). The results showed that time is the most important parameter affecting the performance of the electrocoagulation system. Maximum removal efficiency (96 %) was obtained at a current density of 20 mA/cm2, distance between electrodes of 1.75 cm, salt concentration of 462.5 mg/l, dye concentration of 50 ppm, pH value of 7, and time duration of 15 min. On the other hand, the electrocoagulation efficiency was directly proportional to current density, salt concentration, and contact time, while it was inversely proportional to dye concentration. Isotherm experiments showed that the equilibrium data are best fitted to Freundlich isotherm and sips isotherm; whereas the kinetics results showed that the rate of adsorption followed the pseudo-second-order with an R2 value of 98 %. [ABSTRACT FROM AUTHOR]

This study intends to assess the removal efficiency of the chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) from raw tannery wastewater using electrocoagulation by aluminum electrodes as well as to determine the effects of its main operating factors. Therefore, the response surface methodology was applied through an experimental Box–Behnken design by considering the current intensity (I), treatment time (T), and pH levels as the factors. In addition, the BOD, COD, and TSS removal percentages were considered to be the response variables. The results indicate that the treatment time, current intensity, and pH level were significant for COD and TSS, whereas only the treatment time was significant at a confidence level of p-value < 0.05 for BOD. For COD, the optimal operating conditions were I = 3 A, T = 24 min, and pH = 8.4; for BOD, the optimal operating conditions were I = 3 A, T = 24 min, and pH = 5.5; and for TSS, the optimal operating conditions were I = 2.7 A, T = 19 min, and pH = 7.4. Under these conditions, removal efficiencies of 56.8%, 69.2%, 99.9% were observed for COD, BOD, and TSS, respectively. The results suggest that electrocoagulation is an effective method for removing the parameters under study; therefore, it is a viable alternative for reducing the pollution issues caused by the tannery industry. [ABSTRACT FROM AUTHOR]

In the present study, electrocoagulation (EC), alone or in combination with precipitation or centrifugation, was assessed as a potential pretreatment method for enhanced production of biofuels from 3-phase decanter olive mill wastewater (OMW). Experiments were performed using undiluted and diluted OMW in an EC reactor, operating with a current of 2 A and either Al or Fe electrode materials. Subsequently, diluted OMW was subjected to EC followed by precipitation or centrifugation. The effect of current density (0.05, 0.5 or 1 A) on the combined EC – centrifugation process was assessed and a high reduction of organics was observed for the higher current applied. The different fractions of the pretreated effluents were used as substrates for methane, hydrogen as well as for bioethanol production and the maximum energy recovery was determined in each case. It was shown that, EC at a current of 2 A or further combination with physical methods led to low biofuels yields. However, reduction of the current during EC to 0.05 A or 0.5 A, led to high methane and ethanol yields, with the best scenario being the production of methane yielding an energy equivalent of 1902 kJ/L OMW. • Electrocoagulation (EC) was a promising pretreatment method for OMW. • EC combined with centrifugation led to high removal efficiency of pollutants. • Low current (0.05 A) during EC enhanced biofuels production yields. • Electric energy consumption was 9 kWh/m3 for EC at the optimum conditions. [ABSTRACT FROM AUTHOR]

The present work examined the removal of methylene blue (MB) from aqueous solutions through an electrocoagulation/hazelnut shell (EC/HNS) adsorption coupling process. The process was evaluated using a Box–Behnken design (BBD) under the response surface methodology (RSM). According to the obtained results from BBD–RSM regression analysis, we found that the experimental data are best fitted to the second-order polynomial model with coefficient of determination (R²) value of 0.9534, adjust coefficient (Radj ²) value of 0.9926 and predicted correlation coefficient (RPred ²) value of 0.9973. The maximum MB removal efficiency was obtained under optimized conditions (HNS dosage, 6 g/L; reaction time, 17.75 min; and current density, 2.6 mA/cm²). Under the optimum conditions, the MB removal rate reached 99.45%, and the RSM predictive value was 98.71% with a small deviation. These results confirmed that the RSM model accurately and reliably analysed the process of removing MB from wastewater. [ABSTRACT FROM AUTHOR]

In this work, the mass transfer of aluminum ions in the electrocoagulation reactor was investigated using limiting current density technique by employing a novel rotating impeller anode. The effect of different anode rotational speeds of 75, 100, 150, 200, and 250 rpm with various anode diameters of 9.2, 10.2, and 11.2 cm on limited current values, mass transfer coefficient and COD removal efficiency were studied. Results showed the limited current values increase with the increase of the rotational speed and diameter of the impeller anode. Furthermore, the mass transfer coefficient increases with the increase of rotational speed and impeller diameter. Data for the conditions 11,852 < Re < 58,550 and 88 < Sc < 285 were found to fit the equation for the largest diameter of 11.2 cm; Sh = 2.1 R e 0.93 S c 0.33 . Moreover, the maximum COD removal efficiency was at the largest anode diameter of 11.2 cm, validating the enhancement of aluminum mass transfer by increasing anode diameter. [ABSTRACT FROM AUTHOR]

The electrocoagulation (EC) of dye-polluted aqueous solutions was considered using iron electrodes. In a novel approach, the EC process was simultaneously integrated with ultrasound (US) and H2O2 on the basis of the electro-generation of magnetite nanoparticles via sacrifice anode. Direct red 31 (DR31) dye was chosen as model pollutant. During the short reaction time of 20 min, the US/H2O2/EC process led to the highest decolorization efficiency of 93.3% compared with the US/EC (65.3%) and H2O2/EC (54.1%) processes. The real textile wastewater sample was effectively treated and mineralized by the US/H2O2/EC process (COD removal: 86.7%; TOC removal: 58.7%). [ABSTRACT FROM AUTHOR]

The present work focuses on the feasibility of electrocoagulation (EC) process for the treatment of oil and grease wastewater generated from locomotive wash facilities. Experimental investigations have shown the influence of various factors affecting EC using continuous reactor. The effect of various operating parameters, like reaction time, electrode spacing, and applied voltage, was investigated and optimized using Box-Behnken design method. The optimized value of applied voltage and electrode spacing were found to be 28 V and 3 cm, and Chemical Oxygen Demand removal efficiency obtained was 91.9%. As a result, EC process can be an alternative method for the treatment of oily wastewater. [ABSTRACT FROM AUTHOR]

In this paper, the modeling and the optimization of the removal efficiency of ketoprofen (KTP) by the electrocoagulation process were studied. The central composite design experiments (CCD) method was used to study the main effects and the interaction effects between operational parameters and to optimize the value of each parameter. According to the regression equation obtained, the current density appears to be one of the most important parameters (b2 = +22.11) controlling the removal efficiency of KTP. The positive sign of b2 coefficient suggests that the increase of current density increases the yield of removal. The second significant parameter with a negative effect was the initial KTP concentration (b3 = −16.27). This result suggests that the removal efficiency was inversely proportional to the initial concentration. In addition, according to the model, the most influencing interactions were pH-current density, pH-initial concentration, and current density-initial concentration. The model obtained by CCD led to the following optimal conditions for KTP removal efficiency (96.70%): pH = 7, i = 24.04 mA cm−2, and C0 = 5 mg L−1. [ABSTRACT FROM AUTHOR]

Fluoride (F-) has been removed successfully removal from laboratory prepared fluoride water solution through electrocoagulation using Aluminium (Al) electrode. Consequence of parameters such as pH, current density (CD), initial mass of F- and treatment hour are analyzed over F- removal. The maximum defluoridation of 85.2% occurred at pH 6.5, CD 34.72 A/m² (1A) and contact time of 50 min for starting F- concentration of 50 mg/L in the solution. The kinetic study has been performed to explore the mechanism of electrocoagulation technique, disclosed that the order of the reaction was in the span 2.0-2.07 and 0.05 for fluoride concentration and current density, respectively. This study shows that electrocoagulation using Al electrode has good potential for fluoride removal. [ABSTRACT FROM AUTHOR]

In this study, the performance of glyphosate removal in an electrocoagulation batch with two electrodes formed by the same metal type, consisting of aluminum, iron, steel and copper have been compared. The aim of this study intends to remove glyphosate from an aqueous solution by an electrocoagulation process using metal electrode plates, which involves electrogeneration of metal cations as coagulant agents. The production of metal cations showed an ability to bind together to form aggregates of flocs composed of a combination of glyphosate and metal oxide. Electrocoagulation using aluminum electrodes indicated a high percentage removal of glyphosate, 94.25%; followed by iron electrodes, 88.37%; steel electrodes, 62.82%; and copper electrodes, 46.69%. The treated aqueous solution was then analyzed by Fourier Transform Infrared Spectroscopy. Percentages of Carbon, Hydrogen, Nitrogen, Sulfur remaining in the treated aqueous solution after the electrocoagulation process have been determined. The treated water and sludge were characterized and the mechanism of the overall process was concluded as an outcome. An X-Ray Diffraction analysis of dried sludge confirmed that new polymeric compounds were formed during the treatment. The sludge composed of new compounds were also verified the removals. This study revealed that an electrocoagulation process using metal electrodes is reliable and efficient. Image 1 • Electrocoagulation performance depends on production of metal cations as coagulant. • Metal cations attract glyphosate and bind together to form aggregates of flocs. • Appearance of new polymeric compounds confirmed by FTIR, CHNS and XRD analyses. • Analytical analyses define mechanism of glyphosate removal by electrocoagulation. • Aluminum electrodes indicated a high percentage removal of glyphosate, 94.25%. [ABSTRACT FROM AUTHOR]

In this research, reduction of sludge production and improvement of sludge stabilization degree were aimed, and in this regard, the samples received from an urban wastewater treatment plant were subjected to electrocoagulation (EC) as a disintegration technique. A monopolar EC reactor was designed and iron electrode was used for sludge disintegration. The effect of reaction time, pH and varying current densities on disintegration degree (DD) was determined, and the optimum conditions were found as pH 7, 30 min (reaction time), and 150 A/m2 (current density). DD was found as 84.23%, and soluble chemical oxygen demand was found as 675.2 mg/L under optimum conditions. In this research, the disintegration stage of sludge was defined with the best second-order kinetic model. The operating cost was estimated as 0.078 €/m3 for optimum conditions. Also, the EC-induced disintegration ability of sludge was determined using total suspended solids, total organic carbon, capillary suction time, particle size distribution, specific surface area and viscosity. The findings showed that EC technique can be an effective means for sludge disintegration. [ABSTRACT FROM AUTHOR]

• Al electrodes were more effective than Fe electrode in TOC removal. • The most suibatle current density is determined as 25 mA/cm2. • pH = 5 was determined as the optimum operating pH. • Under the most suitable conditions 65% TOC removal was achieved. • Operating cost was calculated as 1.5 $/m3. In situ treated real textile wastewater was subjected to electrocoagulation for reuse in agricultural irrigation The effect of several parameters such as electrode type (Al and Fe), current density (12.5–100 mA/cm2), initial pH (5–10), and electrocoagulation time (0–120 min) were investigated to determine the optimum electrocoagulation condition. Monopolar electrodes connected in parallel were used for all experiments. The performance of the experiments was mainly evaluated using the Total Organic Carbon (TOC) removal. The Al electrode, 25 mA/cm2 of current density and a pH=5 was selected as the optimum conditions. Under these conditions 42.5% TOC, 18.6% chemical oxygen demand (COD), 83.5% turbidity, 64.7% of the total suspended solids, and 90.3–94.9% color removal efficiencies were achieved. The operating cost was calculated by considering the energy and electrode consumption and evaluated as 1.5 $/m 3 of treated wastewater. The electrocoagulation reaction followed the second order reaction kinetics. [ABSTRACT FROM AUTHOR]

• Electrocoagulation and Biological Fungal integrated system for tannery wastewater. • Chromium Cr+6 content reduced 97% via integrated physicochemical and biologic process. • COD content has removed 96% by integrated Electrocoagulation and Fungal Treatment. • Cost-effective electrocoagulation scenario gives the treatment cost of 0.66 $ m−3. The wastewater from tannery industry, using single treatment technology has not been enough to remove the chromium (Cr6+) or high organic content (COD). Electrocoagulation (EC) and Biological Fungal Treatment (BFT) which endure against toxic and/or highly organic content, are promising technologies to eliminate impurities of tannery wastewaters. In this study, the treatment performance of integrated EC and BFT processes via response surface methodology (RSM) was investigated for the tannery wastewater to determine the effects of operating variables. The factors of electrode combination (Al–Fe), pH (4–8), current density (0.54–0.81 A), and electrolysis time (15–60 min) are investigated for EC and inoculum rate (0.5–2%) reaction time (6–36 h) and pH (4–6) are also investigated for BFT. The operating cost of the combined process was calculated as 1.73 $.m−3. It was determined that efficient COD (63.8%) and Cr6+ (90%) removal were achieved via EC (pH 8.0, 60 min reaction time and 0.81 A current). The optimum condition of BFT for COD and Cr6+ removal are at pH 5.0, 36 h reaction time and 2% inoculum rate. Total efficient COD (96%) and Cr6+ (97%) removal were achieved at EC and BFT with the combined system. [ABSTRACT FROM AUTHOR]

Contamination of the ground water with fluoride is a great problem worldwide. Removal of fluoride (F−) ions from simulated natural waters containing fluoride by electrocoagulation (EC) using aluminum electrodes, has been investigated in a discontinuous lab cell. Two types of water have been studied: local tap water and deionized water-based luoride solutions of sodium fluoride with addition of sodium chloride to reach the desired conductivity. The effect of four operating parameters has been followed for a current density fixed at 5 mA/cm2 within the following ranges: fluoride concentration (5–50 mg/L), temperature (25–55 °C), conductivity (1–6 mS/cm) and initial pH (4–8.5). In accordance with published data, the presence of 61 mg/L buffering hydrogencarbonate ions in the tap water was found to substantially reduce the Al(III) amount required for a given abatement in comparison with deionized water. Performance comparison of the discontinuous electrocoagulation treatment between the two types of water has been discussed for 90% abatement of F− introduced, in terms of the amount of Al(III) dissolved over the initial fluoride concentration, the parameters of a previous adsorption model and the fraction of Al(III) flocs not involved in the adsorption. EC performances were shown to be governed by the solution pH for the two types of water, with little effect of the other operating conditions: at initial pH 6, F− abatement was found to require two or three times less trivalent aluminium than at initial pH 8.5. • Fluoride ions can be removed efficiently from water by electrocoagulation. • Lower aluminium amounts are required with hydrogencarbonate anions. • Temperature, concentration and conductivity impact on the treatment performance. • In any condition, more efficient treatment is obtained with pH lower than 7.5. [ABSTRACT FROM AUTHOR]

This work analyzed the use of electrocoagulation as substitute for sugarcane clarification process using sulfitation. It was evaluated technological parameters (Icumsa color and turbidity), phenolic compounds content and CIELAB color parameters. Four kinetics of reduction color from sugarcane juice were carried out. The essays were divided according to the voltage applied: 35, 45, 55 and 65 V (also based on previous tests). Higher voltage treatments achieved greater reduction of Icumsa color, turbidity and total phenolic compounds. However, none of treatments impacted simple phenolic content analyzed in this work. Tristimulus analysis presented some pattern that went beyond technological analysis, including that 65 V essay changed the pigmentation of sugarcane juice and had an early stabilization on chroma. This kind of results could be useful for industry, once they could correlate quality with different color parameters and finally improve the clarification in general with finer settings of technique according to different situations. Unlabelled Image • The electrocoagulation treatment significantly reduced Icumsa color, turbidity and total phenolic compounds. • All treatments did not influence in simple phenolic content analyzed in this work. • Electrocoagulation can change the pigmentation, chroma and lightness of sugarcane juice. [ABSTRACT FROM AUTHOR]

A large quantity of water is used at oil refineries; Consequently, high amounts of wastewater are produced. The main aim of this study is to evaluate COD removal rate using an electrocoagulation process as well as a photocatalytic process with ZnO nanoparticles. Subsequently, the combined treatment was also implemented to reach energy savings and higher performance. At the optimum condition of the EC process (COD concentration of 900m/L, current density of 20mA/cm², pH of 8.5 and NaCl concentration of 0.5 g/L), COD removal rate was 94% after 60 min. For the photocatalytic process at optimum conditions (COD concentration of 600mg/L, ZnO concentration of 80g/m², pH of 5 and irradiation power of 32 W), 76% of COD removal efficiency was obtained, after 300 min. Thereafter, the combined system was implemented, with initial COD concentration of 1000 mg/L at the optimum conditions; First, the COD removal efficiency was achieved to be 47% after 8.5 min using the EC process; after that, the effluent entered the concrete photoreactor for 120 min, which lead to 85% of COD reduction and final COD concentration reached to 75 mg/L. The GC-Mass analysis was also performed which approved the removal of oil comnpounds from the wastewater. [ABSTRACT FROM AUTHOR]

This study aims to optimize the electrocoagulation(EC) process of emulsified oil removal from polymer-flooding sewage (PFS), producing in the oil recovery process and characterized by multiple chemical additives, high viscosity, and high stability. Response surface methodology (RSM) and Box-Behnken statistical experimental design (BBD) were applied to investigate the effects of tilt angles of electrodes, flow rate, and current density as well as the interactions on oil removal and energy consumption. All the experiments were performed in a continuous-flow pattern with an integrated unit combined with reaction and subsequent separation zone. The experimental results suggested that EC technology was very efficient in oily wastewater treatment and was able to achieve 97% oil removal after the system enters into the stable stage with a flow rate of 5.5 L h−1 ，applied current density of 18.9 mA cm−2 and tilt angle 80°. At this time, the energy consumption is 3.50 kWh m−3. Besides, for both of the oil removal and energy consumption, flow rate has the most significant impact, and the current density follows. The results of variance (ANOVA) analysis showed a high correlation coefficient (R2)value of 0.990 and 0.996 for oil removal and energy consumption, respectively, which ensures an adequate fit of the second-order regression. • Application of a novel integrated apparatus for polymer-flooding sewage treatment by electrocoagulation • Study and optimization of the EC process by response surface methodology • Evaluation of the electrocoagulation performance from the aspect of oil removal and energy consumption • 97% of oil was removed at optimum operating conditions with the energy consumption of 3.5 kWh m−3. [ABSTRACT FROM AUTHOR]

In the present work a combined process is proposed for recovery of metallic copper from industrial electroplating wastewaters comprising electrocoagulation, acidic digestion and electrowinning. The wastewater with the initial Cu2+ ion concentration of 92 mg/L was first subjected to electrocoagulation where it successfully decreased under the upper allowed limit of 2 mg/L. Then, the obtained electrocoagulation sludge was treated with sulfuric acid for digestion and with caustic soda to reach pH 4.8 for precipitation and separation of insoluble aluminum hydroxide, whereas Cu2+ ions remain in solution. Finally, pure metallic copper was produced by electrowinning from the obtained concentrated Cu2+ ions solution. The work proposes the possibility of effectively treating toxic industrial electroplating wastewater accompanied by recovery of significant amounts of valuable pure metals, such as copper. [ABSTRACT FROM AUTHOR]

Highlights • Max. COD removal at 600 mA for 30 min:Al-Al = 68 ± 9%; (Fe-Fe)+air = 60 ± 30%; and Mg-Mg = 27 ± 3%. • Max. OP removal rates (i.e., mg-P/mmol-e):Al-Al, Fe-Fe, and (Fe-Fe)+air = 6.8; Mg-Mg = 0.9. • <0.5 mg-P/L OP achieved in all cases at linearized rate. • Electrocoagulation did not consume alkalinity. • Electrocoagulation with aluminum improved nitrification rates. Abstract Primary influent from a municipal wastewater treatment plant was electrochemically treated with sacrificial aluminum, iron, and magnesium electrodes. The influence of sacrificial anodes on the removal of chemical oxygen demand, total nitrogen, total phosphorus, and orthophosphate during sedimentation was investigated. Nitrification kinetics were assessed on treated supernatant and biogas production was monitored on settled solids. Changes in alkalinity, conductivity, and pH were also recorded. Aluminum and iron electrodes provided high rates of orthophosphate removal (i.e., 6.8 mg-P/mmol-e). Aluminum and iron electrodes also provided similar treatment to equivalent doses of alum and ferric salts (i.e., 38–68% chemical oxygen demand, 10–13% total nitrogen, and 67–93% total phosphorus). The estimated stochiometric ratio of aluminum and iron dosed to orthophosphate removed was approximately 1.3:1 and 4.1:1, respectively. Magnesium electrodes, on the other hand, removed orthophosphate at rates 8–9 times slower than aluminum and iron (i.e., 0.9 mg-P/mmol-e). Magnesium had to be dosed at a ratio of 13.5:1 orthophosphate for phosphorus removal. Orthophosphate removal by magnesium electrodes was most likely limited by electrolysis reactions responsible for increases in pH (i.e., 0.52 pH units/mmol-e). Magnesium electrodes removed 49% chemical oxygen demand and 21% total nitrogen at the high molar ratios required for orthophosphate removal. [ABSTRACT FROM AUTHOR]

Highlights • Molding the electro-dissolution of the Al anode during EC operation. • Predicting both dissolved Al concentration and pH evolution during EC operation. • Simulating the EC operation for arsenic removal from water. Abstract The study of the electro-dissolution of aluminum electrodes during the electrocoagulation process is important for understanding the mechanisms involved in the process. This study involved the experimental determination of both total and dissolved aluminum concentrations during the electrocoagulation processes operation. The total aluminum concentration was fitted with the Faraday's equation and was obtained 1.6 of current efficiency, indicating a super-faradaic behavior of the electrochemical process at the given operating conditions. Additionally, a mathematical model was developed considering the electrochemical dissolution of the Al anode, water electrolysis, hydrolysis of dissolved Al and water dissociation reaction involved in the electrocoagulation process. The simulated results showed a good prediction of the evolution of both concentration of dissolved aluminum and pH during the electrocoagulation process operation. The model was also employed to simulate the removal of arsenic from water by electrocoagulation showing a good prediction of the experimental results at the operating conditions considered. [ABSTRACT FROM AUTHOR]

The electrocoagulation (EC) combined treatment processes have shown promising performances in which the removal of pollutants from industrial wastewater was greatly enhanced. The integration of a free radical producing step with EC has been considered as one of these new combinations that show synergy and improvements in the overall cleaning process performance. This review is devoted to discuss and analyze references on free radicals-assisted EC processes. Different combinations of free radical mechanisms were cited in the literature during the last two decades. They included ozone, advanced oxidation and ultrasound energy-assisted EC. It was noted that most of those studies were lab-scale processes that used synthetic wastewaters rather than real wastewaters. In addition the performances of those combined processes were improved compared to the EC process alone. This review considers the main parameters of free radical EC processes such as mechanisms, kinetic models, scale-up and cost estimation. Many concluding remarks were stated to give insights for possible future investigations. It seems from the results that the ozone-assisted EC is the most efficient combination since its removal efficiency is high in most applications. On the other hand, the combination of ultrasonic energy with EC was reported to reduce electrode passivation. [ABSTRACT FROM AUTHOR]

Highlights • Al activated with In and Zn or Mg is efficient in electrocoagulation. • The removal of Zn2+, Orange II and phosphate was achieved. • The removal efficiency is related to the anode polarisation behaviour. • Al -Zn- In is a promising anode in electrocoagulation. Abstract The simultaneous removal of phosphates, Zn2+ and Orange II, in two synthetic wastewaters was achieved using Al–Mg and Al–Zn–In alloys as anodes at 11.7 mA cm–2 and a surface area to volume ratio of 19.0 m–1. Higher removal efficiencies were obtained with Al–Zn–In, attaining values of 95–96% for phosphate, 99% for Zn2+ and 88–96% for Orange II, while somewhat lower values were seen with Al–Mg, with 89–93% for phosphate, 96% for Zn2+ and 50–60% for Orange II, depending on the solution. The higher efficiency with Al–Zn–In was attributed to its less passive behaviour, which was evident from polarisation plots. Numerous shallow pits, resembling general–like dissolution, were seen with Al–Zn–In, while fewer and larger pits were observed with Al–Mg. The energy demand for the removal of the pollutants was computed as 1.30 and 2.55 kWh m–3 for the Al–Zn–In and Al–Mg anodes, respectively. The removal of phosphates and Orange II was explained in terms of the generation of cationic polynuclear aluminium species that provide electrostatic interactions with the anionic phosphates and Orange II. The removal of Zn2+ was attributed to the formation of insoluble Zn(OH) 2. [ABSTRACT FROM AUTHOR]

Abstract Ferrous ions are the major Fe species generated from sacrificial iron anodes, but ferric ions are the more active ingredients for the removal of organic matters in the acidic pH region. Therefore, a novel high-pressure electrocoagulation (HPEC) system was devised to facilitate the Fe(II)-to-Fe(III) conversion under acidic pH conditions. The effects of operation pressure (0–3 bar) and initial pH value (3–10) on the removal of color and organics from synthetic dye wastewater containing Eriochrome Black T (EBT) were investigated. The operation costs of the HPEC were compared with that of the conventional electrocoagulation (CEC) processes. The HPEC outperformed the CEC, achieving complete color removal after a short reaction time. In the initial pH range of <8, the HPEC achieved substantial color (∼100%) and organic carbon (∼78%) removals. However, a sharp drop in the removal efficiency occurred at the pH of >8 owing to the formation of Fe(III)-EBT complexes and the ineffective removal of these complexes by coagulation or adsorption. The high removal efficiencies attained under acidic and neutral pH conditions were attributed to the effective Fe(II)-to-Fe(III) conversion by dissolved oxygen under pressure followed by the formation of Fe(OH) 3 precipitates. The HPEC saves significant operating costs (45–70%) compared to the CEC process. Highlights • High-pressure electrocoagulation (HPEC) system is developed for efficient dye removal. • Effects of reaction time, initial pH, and pressure on dye removal are investigated. • The HPEC outperforms the conventional electrocoagulation. • Dye removal is substantial at acidic pH, but becomes insignificant at alkaline pH. • The HPEC saves the operational costs substantially due to rapid reactions. [ABSTRACT FROM AUTHOR]

In this study, it was investigated the treatability of real wastewater from textile industry by electrochemical treatment methods (electrocoagulation and electrooxidation). Effect of important operating parameters such as, electrode type and combination (Al-Al, Fe-Fe, Al-Fe, Fe-Al, Pt-Fe), pH, reaction time and potential were investigated on removal efficiency of color and chemical oxygen demand (COD). The initial color and COD concentrations of the wastewater were 395 Pt-Co and 1040 mg/L, respectively. At the end of the electrocoagulation experiments, concentrations of color and COD were decreased to 28 Pt-Co and 115 mg/L, respectively. Results showed that at pH 3 and 6 V potential, up to 93% color and 89% COD removal efficiencies were obtained in the reactor consisting of Fe-Fe electrodes. COD and color were removed at the rate of 88% and 92%, respectively in the study done with Al-Al couple at 10 V in natural pH (6.96). COD removal was achieved in the ratio of 93% at 6V as a result of the electrooxidation study with a couple of Pt-Fe electrodes. The study showed that the removal process was promising and it was reached to the discharge limit values for the color and COD with each electrode couple specified in the regulation. When considering the removal efficiencies, electrocoagulation process is the best treatment method is for this study. In terms of energy consumption, the electrooxidation process is more economical to effectively remove COD. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ozonation (O 3) and electrocoagulation (EC) work well in a salty wastewater matrix. • EC-O 3 treatment gives more than 95% color removal in a very short time (18 min). • Ozone dose can be reduced more than 5 times when EC is coupled with O 3 treatment. • Two-step EC → O 3 treatment was more economically justified. • Recycling of purified brine in a subsequent dyeing operation gave very promising results. Abstract Industrial textile wastewater is usually characterized by high pH, intense color and extremely high salinity, especially in case of wastewater generated after dyeing. Due to the complex matrix of textile wastewater, the selection of an appropriate treatment method can be a challenge. This paper presents the advantages of coupling electrocoagulation (EC) and ozonation (O 3) as one-step (EC + O 3) and two-step (EC → O 3) operations. The combination of EC and O 3 , which both worked well in salty environment, gave very good results in the case of aqueous solutions and real industrial wastewater containing Reactive Black 5 (RB5). Very high color removal, more than 95%, was achieved in a very short treatment time (less than 18 min, while ca. 60 min was required in the case of individual O 3). At the same time the applied ozone dose was reduced from 1.69 g/L, when using O 3 only, to less than 0.3 g/L for EC → O 3. The results of color removal and mineralization analysis indicated the high efficiency of both the EC + O 3 and EC → O 3 processes; however, the cost evaluation revealed that the EC → O 3 treatment was more advantageous. EC preformed as a single treatment resulted in an increase in toxicity, but coupling EC with O 3 reduced this undesirable effect. Very promising results were obtained in recycling trials. The color difference (DE cmc , according to ISO 105-J03) of textiles dyed with purified wastewater (brine) were between 0.28 and 0.98 (below the limiting value of 1.5). [ABSTRACT FROM AUTHOR]

Highlights • Oily wastewater was treated utilizing electrocoagulation-microfiltration in batch mode. • Electrocoagulation parameters were current density, electrode distance and initial pH. • 75–85% of the initial flux was lost during the microfiltration of the electrocoagulated samples. • Oil and grease contents were lowered to 10.2 mg/L. Abstract The present work deals with the utilization of electrocoagulation-microfiltration in batch mode for the treatment of oily wastewater containing oil, grease along with metals like Na, Cr, Cu, Pb, and Ni. Samples were pre-treated using the electrocoagulation by varying working parameters such as current density (20–80 A/m2), electrode distance (0.005–0.2 m) and initial pH (3.6–8.7). The concentration of oil and grease was reduced from 35 mg/L to 10.2 mg/L in just 20 min. Microfiltration was carried out using indigenously prepared ceramic membranes to remove these flocs generated during the electro-coagulation process at three different pressures of 98,196 and 194 kPa. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The new aluminium-based EC reactor, PBPR, removed 99 mg/L of phosphate within 60 min. • PBPR produced enough hydrogen gas to generate 4.34 kWh/m3 of power. • The influence of the operating parameters on phosphate removal could be modelled with an R2 of 0.882. • SEM images showed many dents on the anode due to the production of Al hydroxides. Abstract The current study investigates the removal of phosphate from water using a new baffle plates aluminium-based electrochemical cell (PBPR) taking consideration the influence of key operating parameters. This new cell utilises perforated baffle plates as a water mixer rather than magnetic stirrers that require extra power to work. As this unit is new, a comprehensive study has been carried to assess it performance. This study also includes preliminary estimates of the reactor's operating costs, the amount of H 2 gas produced and the yieldable energy from it. SEM (scanning electron microscope) was used to investigate the influence of the electrocoagulation process on the morphology of the surface of aluminium electrodes, and an empirical model developed to reproduce the phosphate removal process. The results showed that 99% of phosphate was removed within 60 min of electrolysis at an initial pH (ipH) of 6, inter-electrode distance (ID) of 0.5 cm, current density (J) of 6 mA/cm2, initial concentration of phosphate (IC) of 100 mg/L, and minimum operating cost of 0.503 US $/m3. The electrochemical cell produced enough H 2 gas to generate 4.34 kWh/m3 of power. Statistically, it was proved that the influence of the operating parameters on phosphate removal could be modelled with an R2 of 0.882, the influence of these operating parameters on phosphate removal following the order: t > J > I C > i p H > I D. Finally, SEM images showed that after several electrolysing runs, the Al anode became rough and nonuniform which could be related to the production of aluminium hydroxides. [ABSTRACT FROM AUTHOR]

Effluent found in the pulp and paper industry can cause considerable damage if it is discharged untreated, because of the high biochemical and chemical oxygen demands. Electrocoagulation is a physicochemical process widely used in industrial wastewater treatment. The removal of different pollutants depends on the sample type and operating conditions. The aim of this research was to evaluate the efficiency of an electrocoagulation system for COD removal from recycled paper production effluent via aluminum and iron electrodes. Different operational parameters, such as the electrolysis time (5 min to 15 min), current density (7 A/m² to 11 A/m²), and distance between each electrode (5 mm to 20 mm), were evaluated. The turbidity, total suspended solids, chlorides, sulfates, and COD had removal efficiencies of 92.7%, 91.3%, 70.4%, 66.6%, and 64%, respectively. A polynomial model was generated to estimate the optimum conditions for COD removal. The optimum times for the current densities 7 A/m², 8 A/m², 9 A/m², 10 A/m², and 11 A/m² were 39.5 min, 39.5 min, 35.7 min, 34.1 min, and 32.8 min, respectively, with a 15-mm electrode gap. [ABSTRACT FROM AUTHOR]

Highlights • Application of electrocoagulation in RO brines is advantageous due to high conductivity of brines. • Electrocoagulation effectively removed phosphate, alkalinity and DOM with either Fe or Al anode. • DOM removal resulted more effective with Al than Fe anode due to partial oxidation of iron at pH 5.5. • Electrocoagulation coupled with AOP oxidized micropollutants in brines to a high extent. Abstract The potential of integrating electrocoagulation (EleC) with two-stage reverse osmosis (RO) to enhance desalination of secondary/tertiary effluents through removal of dissolved organic matter (DOM) and scaling salts from brines was studied. EleC appears advantageous due to the high electrical conductivity of RO brines and low residual ions concentration. EleC was performed in batch mode in a flow-through cell with recirculation through a stirred reservoir at 9.4 mA/cm2 current density. Anode was made of Fe or Al as indicated, and cathode of stainless steel. Chemical coagulation (CC) with FeCl 3 was tested as reference. EleC resulted in effective removal of phosphate (>99%), carbonate (88–98%) and DOM (40–50%) at a high Faradaic efficiency (>90%). Fe-EleC resulted less suitable than Al-EleC due to partial Fe(II) oxidation at pH 5.5 required for optimal DOM removal, leaving high Fe content and consequently turbidity in the supernatant, whereas residual Al was negligible. At optimal conditions Al release was 75 mg/L for 1st-stage brines-RO1 (2-fold concentrated) and 300 mg/L for 2nd-stage brines-RO2 (∼8.3-fold concentrated), corresponding to a specific energy consumption of 0.30 and 0.23 kWh/dm 3 mS/cm , respectively. Similar results were obtained with CC, however, its main disadvantage was the considerable increase of chlorides in the supernatant. Since coagulation removes quenching components from brines, coupling EleC with advanced oxidation processes (AOP), either UVA/TiO 2 or UVC/H 2 O 2 , was also evaluated for oxidation of model micropollutants from brines prior to discharge. Either EleC or CC in tandem with AOP increased micropollutants oxidation by 3–4 fold compared to raw brines, achieving practically complete transformation. [ABSTRACT FROM AUTHOR]

Highlights • First time evaluation of OH anodic production in electrocoagulation (EC) process. • First time evaluation of OH photochemical production in photoelectrocoagulation (PEC) process. • Large removal of TSS, turbidity and color from car wash wastewater by EC and PEC. • Poor TOC removal in EC and PEC, due to main action of active chlorine and Fe(OH) n. • Production of OH photochemical in electro-oxidation with Ti|IrO 2 -Ta 2 O 5 anode and UVC light. Abstract In this study, we evaluate for the first time the effect of ionic composition on the anodic production of hydroxyl radical (OH a) during electrocoagulation (EC) process in batch using carbon steel electrodes. Likewise, hydroxyl radical production from active chlorine (OH ph) electrogenerated in EC photoassisted with UVA (λ = 365 nm) and UVC light (λ = 254 nm) was evaluated using car wash wastewater. Both, OH a and OH ph , were analyzed by UV–Vis spectroscopy and fluorescence using coumarin as the probe. Under optimal conditions (j = 8 mA cm−2, 25 °C, 15 min, 6 rpm), turbidity, suspended solids and color were removed by 98.3%, 98.7% and 93.1%, respectively. However, total organic carbon (TOC) abatement only attained 27%. This can be related to the fact that OH a and OH ph were not identified during EC, with or without UV irradiation. Hence, the organic matter is mainly removed by coagulation with Fe(OH) n species. Comparative treatment of the same wastewater by electrochemical oxidation (EO) with a Ti|IrO 2 -Ta 2 O 5 anode in the presence of electrogenerated active chlorine and UVC light demonstrated the generation of OH ph , thus encouraging the potential coupling of EC with EO. [ABSTRACT FROM AUTHOR]

Highlights • Poor BHA and DOC decays in simulated matrix and urban wastewater by EC with Fe|Fe cell. • Active chlorine formed in simulated matrix accelerates BHA decay in EO-H 2 O 2. • Large mineralization of BHA in simulated matrix by EF and PEF with BDD/air-diffusion cell. • Growing mineralization in urban wastewater at pH 7.9: EO-H 2 O 2 < EF < PEF, greater with BDD. • Better performance of EF and PEF in urban wastewater at pH 3.0 by greater generation of OH. Abstract This work compares the removal of butylated hydroxyanisole (BHA), a ubiquitous antioxidant in food and pharmaceuticals, from water either by electrocoagulation (EC) with an Fe|Fe cell or H 2 O 2 -based electrochemical advanced oxidation processes like electrochemical oxidation (EO-H 2 O 2), electro-Fenton (EF) and photoelectro-Fenton (PEF) with an air-diffusion cathode. BHA degradation by EC was very poor, whereas the dissolved organic carbon (DOC) was more effectively abated in urban wastewater. The effect of pH, number of Fe|Fe pairs and current on the EC performance was examined. The additive was also slowly degraded by EO-H 2 O 2 with a RuO 2 -based or BDD anode in 50 mM Na 2 SO 4 solution. In the simulated matrix, BHA decay by EO-H 2 O 2 was substantially enhanced owing to active chlorine generation from anodic oxidation of Cl−, whereas the OH-mediated oxidation at the BDD surface accounted for DOC decay. In EF and PEF, the OH produced in the bulk upgraded the mineralization, primordially using BDD. In raw urban wastewater at natural pH 7.9, the time course of BHA and DOC contents was affected by NOM oxidation, being accelerated in the order: EO-H 2 O 2 < EF < PEF. The quickest decontamination of urban wastewater occurred in PEF at pH 3.0, because of the higher amounts of OH in the bulk along with UVA photolysis. [ABSTRACT FROM AUTHOR]

Highlights • Fluoride and arsenic removal from real groundwater by electrocoagulation. • Aluminum electrodes in a continuous filter-press reactor with three cell stack. • Hydrated silica species in groundwater facilitate the removal of F and As. • XRD and FTIR analyses indicated that flocs are composed by aluminum silicates. • Fluoride and arsenic concentrations after EC met the WHO standard. Abstract An electrocoagulation (EC) process to remove fluoride and arsenic from groundwater (fluoride 5.5 mg L−1, arsenic 50.4 µg L−1, hydrated silica 132 mg L−1, sulfate 40 mg L−1, nitrate 6.7 mg L−1, phosphate 0.55 mg L−1, hardness 23 mg L−1, alkalinity 59.0 mg L−1, pH 8.5 and conductivity 824.5 µS cm−1) was investigated. The EC was carried out in a filter-press flow reactor, containing a three-cell stack equipped with aluminum electrodes. The influence of current density (j), mean linear flow rate in the EC reactor (u r) and the co-existing ions on the fluoride and arsenic removal efficiencies was analyzed. All EC tests, performed at 0.23 ≤ u r ≤ 0.93 cm s−1 and 5 ≤ j ≤ 7 mA cm−2, satisfied the World Health Organization (WHO) standard for fluoride (C F - ≤ 1.5 mg L−1). The EC tests that satisfied the WHO standard for arsenic (C As ≤ 10 µg L−1) were at 0.23 cm s−1 and 6 ≤ j ≤ 7 mA cm−2. Spectroscopic analyses on aluminum flocs showed that these are mainly composed of aluminum silicates. Fluoride replaces a hydroxyl group from aluminum flocs and arsenates adsorb on aluminum aggregates. The best EC test in terms of energy consumption (6.7 kWh m−3) was obtained at 0.23 cm s−1 and 6 mA cm−2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • It is feasible to apply the electrocoagulation (EC) process to decontaminate steel contaminated with U. • Contaminated metal is used as the sacrificial anode and the cathode Ti. • Decontamination efficiency depends on geometry, dimensions and surface conditions of the metal. • The grease or dust presence on the metal surface reduces the treatment efficiency. • Iron hydroxides formed in the EC process carry to U to the sludges. Abstract The decontamination of noncompactable radioactive wastes, such as tools and equipment, aims to reduce the waste volume to be conditioned and stored. The electrocoagulation (EC) application in the decontamination of noncompactable radioactive waste from stainless steel containing uranium, was studied to evaluate its technical viability. The first studies were carried out with stainless steel plates coated with WO 3 to simulate a fixed contamination and to determine the best tungsten removal conditions via EC considering pH, electrolyte support, distance between the electrodes, cell potential and counter-electrode material. The best removal conditions for WO 3 were applied to plates contaminated with UO 2 (NO 3) 2 to evaluate the viability of the EC decontamination process. Uranium removal efficiencies of 90% were obtained in 1 h, at pH of 1, 2.4 V and 1 cm of distance between anode / cathode in a circular array. The EC process, under the previously obtained conditions, was applied to two metallic pieces contaminated with U. It proved feasible to decontaminate metallic pieces through the EC process, thus being able to obtain up to 90% U removal efficiency; however, it is important that the surfaces of the parts are free of grease and dust. [ABSTRACT FROM AUTHOR]

In this work, feasibility of electrocoagulation (EC) process with Al and Fe scrap anodes for treatment of groundwater contaminated with arsenic (As) was examined as a cheaper treatment alternative for affected remote communities. EC experiments were carried out in a batch packed-bed EC reactor and the effect of applied current (0.010–0.100 A), type of scrap electrode (Fe and Al), packed-bed density (0.1–0.4 kg/m³ for Fe and 0.02–0.08 kg/m³ for Al) and EC time were investigated. Optimum operating conditions to obtain maximum contaminant level (MCL) of 10 μg /L for total As (>93% removal) in groundwater samples were determined as 8 min and 0.05 A for Fe scrap anodes. Whereas for Al scrap anode, 30 min and 0.10 A were the optimums. The operating cost, energy and electrode consumptions at these optimums were calculated as 0.017 US $/m³, 0.070 kW h/m³ and 0.052 kg/m³ for Fe anodes and 0.181 US $/m³, 0.876 kW h/m³ and 0.067 kg/m³ for AL anodes respectively. The As removal slightly decreased with decrease in anode bed density. Moreover, Fe scrap anodes exhibited better As removal than the Al scrap anodes at all tested conditions. The scanning electron microscopy (SEM) of the electro-coagulated sludge revealed irregular and porous particles with amorphous structure. The Fourier-transform infrared spectroscopy (FTIR) showed bonding between Fe(III) - As(V), and As—O bond, confirming As removal by co-precipitation and adsorption, respectively in the EC process. [ABSTRACT FROM AUTHOR]

Most studies investigated electrocoagulation/electroflotation process (EC/EF) using either aluminum or iron electrodes. The main aim of this study is to investigate the performance of EC/EF to treat printing wastewater under various experimental conditions using copper electrodes. The effects of several variables, including different electrode materials (copper and aluminum), different current densities, electrolysis time, and spacing between electrodes on the removal efficiency of various parameters were investigated. The results showed that the maximum removal efficiencies for COD,TDS, and oil and grease were obtained when using a copper electrode. The maximum removal efficiencies were obtained at a gap distance of 4 cm. [ABSTRACT FROM AUTHOR]

Effluents from many industries are one of the major sources of water pollution and represent important environmental problems. Generally, paper recycling process generates large amounts of wastewater. Electrocoagulation (EC) is an evolving technology that has been effectively applied in the treatment of industrial wastewater containing various pollutants, such as textile wastewaters or chemical mechanical polishing wastewaters. This technique has a great ability to remove the pollutants from water due to its high efficiency, economically attractive and relatively lower sludge formation compared with other conventional processes such as biological, physical, chemical, adsorption and advanced oxidation processes. However, electrocoagulation (EC) process has been proposed as alternative to biological, physical and chemical methods due to its environmentally friendly and cheap to operate. This paper presents the experimental results obtained by applying the electrocoagulation method for removing the organic pollutants (COD) and total suspended solids (TSS) from wastewaters generated in the paper mill that use as raw materials recycled papers. [ABSTRACT FROM AUTHOR]

Graphical abstract A novel electrocoagulation (EC)-carbon membrane coupling with electrochemical anodic oxidation (CM/EAO) integrated system was designed and constructed for oily wastewater treatment. Abstract A novel electrocoagulation (EC)-carbon membrane coupling with electrochemical anodic oxidation (CM/EAO) integrated system was designed and constructed for oily wastewater treatment. Electrocoagulation was adopted as a primary unit, and the effects of many parameters, including current density, electrolyte concentration, initial pH, feed oil concentration, and operating time on pretreatment performance were investigated and optimized. Subsequently, CM/EAO was set as a secondary unit for further deep purification of the EC effluent. The results showed the integrated system had great potential for oil removal from wastewater. The EC unit could remove nearly half of COD and TOC in the feed, and the following CM/EAO unit further degraded the EC effluent, and the COD, and TOC were reduced to 13 mg/L and 22 mg/L, respectively. The mechanisms involved in each stage were proposed. A large proportion of oil droplets in oily wastewater were firstly removed by electrocoagulation process, and the remaining oil droplets were further decomposed into small molecules or even into CO 2 and H 2 O by hydroxyl radicals generated from electrochemical anode oxidation reactions. The degraded intermediate products including various n-alkanes and polycyclic aromatic hydrocarbons were identified by GC MS. [ABSTRACT FROM AUTHOR]

Abstract In order to intuitively and clearly evaluate the potential and current distribution, the fluid flow and mixing, as well as mass transfer involved in electrocoagulation process for As and Sb removal, numerical simulation of electric field, flow field and mass transfer were constructed by Comsol Multiphysics and verified by experiments. Results displayed that the primary current and potential distribution were improved by changing electrode distance or adding insulator in a batch reactor. When configuration 2 and 2 cm electrode distance were applied, a more uniform primary current distribution and higher electrode current efficiency were obtained. In a continuous flow reactor, the increase of flow rate resulted in the left shift of the peak in residence time distribution curve, gradual decrease of the tailing area, reduction of the stagnation zone, and more uniform mixing of the fluid. However, higher than 0.043 L/min was unfavorable to the formation of flocs and its effective combination with pollutants. According to the simulation of mass transfer, at the initial stage, the rate of electrolysis/hydrolysis was greater than that of mass transfer. Fe2+, OH−, and Fe(OH) 2 were primarily concentrated on the anode, cathode, and between the two electrodes, respectively. Under the action of electromigration, diffusion and convection, the concentration distribution of Fe(OH) 2 increased at the direction of streamline. The concentration of Fe2+ and OH− achieved the minimum value at the outlet. However, Fe(OH)+ concentration and distribution were hardly affected by the treatment time, and once generated, immediately proceed to the next hydrolysis reaction. Graphical abstract Image 1 Highlights • The primary current and potential distribution with different reactor configurations were modeled and improved. • The hydrodynamics of EC system were evaluated and the continuous flow reactor was optimized. • The diffusion, migration and convection of typical products were systematically analyzed. [ABSTRACT FROM AUTHOR]