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Pulse electro-coagulation (PEC) was applied to treat plastic factory wastewater in this study. One representative plasticizer molecule was chosen for the synthetic wastewater: dibutyl phthalate (DBP). Experiments demonstrated that PEC exhibits superior economic efficiency and removal efficiency compared to traditional electro-coagulation in wastewater treatment. Experimental data also indicated that at a given current density, compared with the aluminum electrode, the iron electrode could more efficiently remove DBP from wastewater. With an initial pH of 8-9, the required energy was 2.5 kWh m-3 for 75% DBP removal in the case of iron as the anode type. In general, the pollutants have been successfully reduced to environmentally acceptable levels under the following operating conditions: iron as the anode type, interelectrode distance of 10 mm, duty cycle of 0.6, pH of 8-9 and current density of 15 mA cm-2 for PEC time>15 min. [ABSTRACT FROM AUTHOR]

This study investigated for the first time the use of electrocoagulation (EC) in the batch mode with aluminum or iron electrodes for the preliminary purification of volatile fatty acids (VFA) in a digestate from acidogenic fermentation. The respective influences of electrolysis time, electrode material, current density, inter-electrode distance and initial pH (pH i ) on the efficiency of the process were investigated. Experimental results showed that VFA were totally found in the liquid phase at the end of EC in all cases, while EC removed efficiently (>80%) solids and other soluble compounds including nitrogenous and phosphorous species. Reduction of EC operating cost was achieved by working at the lowest current density (9.3 mA/cm 2 ) and at the lowest inter-electrode distance (1.0 cm), independently from pH i . Operating costs were evaluated to be 0.26 ± 0.03 and 1.07 ± 0.04 US $/m 3 with iron or aluminum electrodes, respectively. [ABSTRACT FROM AUTHOR]

The cationic dye malachite green (MG) and the anionic dye Remazol yellow (RY) were removed from aqueous solutions using electrocoagulation-adsorption processes. Batch and continuous electrocoagulation procedures were performed and compared. Carbonaceous materials obtained from industrial sewage sludge and commercial activated carbons were used to adsorb dyes from aqueous solutions in column systems with a 96–98% removal efficiency. The continuous electrocoagulation-adsorption system was more efficient for removing dyes than electrocoagulation alone. The thermodynamic parameters suggested the feasibility of the process and indicated that the adsorption was spontaneous and endothermic (ΔS=0.037 and −0.009 for MG and RY, resp.). The ΔG value further indicated that the adsorption process was spontaneous (−6.31 and −10.48; T=303 K). The kinetic electrocoagulation results and fixed-bed adsorption results were adequately described using a first-order model and a Bohart-Adams model, respectively. The adsorption capacities of the batch and column studies differed for each dye, and both adsorbent materials showed a high affinity for the cationic dye. Thus, the results presented in this work indicate that a continuous electrocoagulation-adsorption system can effectively remove this type of pollutant from water. The morphology and elements present in the sludge and adsorbents before and after dye adsorption were characterized using SEM-EDS and FT-IR. [ABSTRACT FROM AUTHOR]

Arsenic contamination in drinking water is a major issue in the present world. Arsenicosis is the disease caused by the regular consumption of arsenic contaminated water, even at a lesser contaminated level. The number of arsenicosis patients is increasing day-by-day. Decontamination of arsenic from the water medium is the only one way to regulate this and the arsenic removal can be fulfilled by water treatment methods based on separation techniques. Electrocoagulation (EC) process is a promising technology for the effective removal of arsenic from aqueous solution. The present review article analyzes the performance of the EC process for arsenic removal. Electrocoagulation using various sacrificial metal anodes such as aluminium, iron, magnesium, etc. is found to be very effective for arsenic decontamination. The performances of each anode are described in detail. A special focus has been made on the mechanism behind the arsenite and arsenate removal by EC process. Main trends in the disposal methods of sludge containing arsenic are also included. Comparison of arsenic decontamination efficiencies of chemical coagulation and EC is also reported. [ABSTRACT FROM AUTHOR]

Tilt angle of parallel-plate electrodes (APE) is very important as it improves the economy of diffusion controlled Electrocoagulation (EC) processes. This study aimed to evaluate and optimize APE of a self-made EC device including integrally rotary electrodes, at a fixed current density of 120 Am −2 . The APEs investigated in this study were selected at 0°, 30°, 45°, 60°, 90°, and a special value ( α (d) ) which was defined as a special orientation of electrode when the upper end of anode and the lower end of cathode is in a line vertical to the bottom of reactor. Experiments were conducted to determine the optimum APE for demulsification process using four evaluation indexes, as: oil removal efficiency in the center between electrodes; energy consumption and Al consumption, and besides, a novel universal evaluation index named as evenness index of oil removal efficiency employed to fully reflect distribution characteristics of demulsification efficiency. At a given plate spacing of 4 cm, the optimal APE was found to be α (d) because of its potential of enhancing the mass transfer process within whole EC reactor without addition, external mechanical stirring energy, and finally the four evaluation indexed are 97.07%, 0.11 g Al g −1 oil, 2.99 kwhkg −1 oil, 99.97% and 99.97%, respectively. [ABSTRACT FROM AUTHOR]

In this study, a laboratory scale for the treatment of a recalcitrant and toxic synthetic wastewater containing diazo dye, acid brown 14 (AB-14) has been comparatively performed by two electro-catalytic treatment processes, namely anodic oxidation (AO) and electrocoagulation (EC) using a new batch electrochemical cell. Additionally, the influence of several operating parameters such as; current density (j), initial dye concentration (C o ), NaCl concentration (C N ), and pH on the color removal efficiency and chemical oxygen demand (COD) are evaluated. The powerful capability of the AO and EC of AB-14 which related to the mechanistic reaction pathway is shown. The poor degradation is ascribed to higher C o and pH, while the enhancement of j and C N is responsible for better degradation of AB-14 dye. The results indicate that the EC is more effective than AO under the same operational condition. A kinetic model is developed for evaluation of the pseudo-first-order-rate constant (k app ) as a function of various operational parameters. The results emphasize the high efficiency of AO and EC and the clean processes which are hopeful alternative for the treatment of the large volume wastewater of the textile industry. [ABSTRACT FROM AUTHOR]

A new batch, flow column electrocoagulation reactor (FCER) that utilises a perforated plate flow column as a mixer has been used to remove fluoride from drinking water. A comprehensive study has been carried out to assess its performance. The efficiency of fluoride removal (R%) as a function of key operational parameters such as initial pH, detention time (t), current density (CD), inter-electrode distance (ID) and initial concentration (C 0 ) has been examined and an empirical model has been developed. A scanning electron microscopy (SEM) investigation of the influence of the EC process on morphology of the surface of the aluminium electrodes, showed the erosion caused by aluminium loss. A preliminary estimation of the reactor's operating cost is suggested, allowing for the energy from recycling of hydrogen gas hydrogen gas produced amount. The results obtained showed that 98% of fluoride was removed within 25 min of electrolysis at pH of 6, ID of 5 mm, and CD of 2 mA/cm 2 . The general relationship between fluoride removal and operating parameters could be described by a linear model with R 2 of 0.823. The contribution of the operating parameters to the suggested model followed the order: t > CD > C 0 > ID > pH. The SEM images obtained showed that, after the EC process, the surface of the anodes, became non-uniform with a large number of irregularities due to the generation of aluminium hydroxides. It is suggested that these do not materially affect the performance. A provisional estimate of the operating cost was 0.379 US $/m 3 . Additionally, it has been found that 0.6 kW/m 3 is potentially recoverable from the H 2 gas. [ABSTRACT FROM AUTHOR]

This work focuses on the removal of sulfate from mining waters by using electrocoagulation with iron electrodes. A comparison of the results obtained by electrocoagulation with those obtained with the application of conventional chemical coagulation is provided. The results show that sulfate can be removed from synthetic mining waters by electrocoagulation, and that the pH and coagulant dosage play a very important role. During chemical coagulation under acidic conditions, it is possible to use a low dosage of iron and remove more than 80% of the sulfate present in water. However, chemical coagulation seems to behave as a kind of ion-exchange process (from the viewpoint of effluent quality). Thus, significant concentrations of accumulated chloride (counter ion of iron in the coagulant added) prevents the use of the technology. This problem is avoided by the application of electrocoagulation, which attains good efficiencies that can be even increased by using a continuous process with a flocculation tank. This technology also helps to remove other ionic pollutants contained in the wastewater. [ABSTRACT FROM AUTHOR]

This paper studies electro-coagulation (EC) as a potential alternative to chemical coagulation for the treatment of water and wastewater. Prior research around this technology has been centred on application-specific research leading to a lack of fundamental studies and understanding of the process principles governing the technology. Developing on previous work, a theoretical study employing model solutions of arsenic is presented to demonstrate not only how it is possible to systematically evaluate the performance of the process, but also how process performance is regulated by the amount of coagulant in solution and, therefore current intensity employed. The data is in strong contrast with literature reporting on the impact of flow rate and current density on process performance. Here it is demonstrated that when the key process parameter – dosed coagulant concentration – is kept constant, variation of flow rate and current density does not affect process performance. [ABSTRACT FROM AUTHOR]

Pharmaceuticals as severe contaminants of surface and ground water around the manufacturing communities and residential zones received growing attention recently. Since, there is no report on ciprofloxacin (CIP) removal using electrocoagulation (EC) process by aluminum electrodes, the present work deals with efficient removal of CIP from hospital wastewater using mentioned method. Response surface methodology (RSM) was used to evaluate the main effects of parameters, their simultaneous interactions and quadratic effect to achieve the optimum condition for EC process. According to the obtained results from regression analysis, it was found that the experimental data are best fitted to the second-order polynomial model with coefficient of determination (R²) value of 0.9086, adjust correlation coefficient (Adj. R²) value of 0.8796 and predicted correlation coefficient (pred. R²) value of 0.7834. EC process was applied successfully with removal efficiency of 88.57% under optimal operating condition of pH 7.78, inter-electrode distance 1 cm, reaction time 20 min, current density 12.5 mAcm-2 and electrolyte dose of 0.07 M NaCl with the initial CIP concentration of 32.5 mg L-1. The experimental efficiency was in satisfactory agreement with the predicted efficiency of 90.34%. The obtained results revealed that, sweep flocculation as a determinant mechanism controlled the adsorption of CIP molecules on aluminum hydroxide precipitates. Electrode consumption and electrical energy consumption were found to be 66.80 gm~3 and 0.613 kWh m-3, respectively. The obtained results from real sample analysis revealed that the initial CIP concentration of 154 ± 6 μg L-1 of hospital wastewater were found to reached to zero after applying optimal condition of EC process. [ABSTRACT FROM AUTHOR]

In this investigation, a new bench-scale electrocoagulation reactor (FCER) has been applied for drinking water denitrification. FCER utilises the concepts of flow column to mix and aerate the water. The water being treated flows through the perforated aluminium disks electrodes, thereby efficiently mixing and aerating the water. As a result, FCER reduces the need for external stirring and aerating devices, which until now have been widely used in the electrocoagulation reactors. Therefore, FCER could be a promising cost-effective alternative to the traditional lab-scale EC reactors. A comprehensive study has been commenced to investigate the performance of the new reactor. This includes the application of FCER to remove nitrate from drinking water. Estimation of the produced amount of H 2 gas and the yieldable energy from it, an estimation of its preliminary operating cost, and a SEM (scanning electron microscope) investigation of the influence of the EC process on the morphology of the surface of electrodes. Additionally, an empirical model was developed to reproduce the nitrate removal performance of the FCER. The results obtained indicated that the FCER reduced the nitrate concentration from 100 to 15 mg/L (World Health Organization limitations for infants) after 55 min of electrolysing at initial pH of 7, GBE of 5 mm, CD of 2 mA/cm 2 , and at operating cost of 0.455 US $/m 3 . Additionally, it was found that FCER emits H 2 gas enough to generate a power of 1.36 kW/m 3 . Statistically, the relationship between the operating parameters and nitrate removal could be modelled with R 2 of 0.848. The obtained SEM images showed a large number dents on anode's surface due to the production of aluminium hydroxides. [ABSTRACT FROM AUTHOR]

Electrocoagulation (EC) presents operational advantages over chemical coagulation, including no requirement for the addition of chemicals. This work compares the performance of electrocoagulation in two stages of the urban water cycle: drinking water production and wastewater regeneration. A case study focussed on the treatment of actual effluents from different locations in the centre of Spain is performed. It was observed that electrocoagulation with aluminium anodes is an efficient technique to remove turbidity and total organic carbon (TOC) from surface water and to deplete turbidity andEscherichia coli(E. coli) from urban treated wastewater (taken from the outlet of an urban wastewater treatment facility, WWTF). Although electrocoagulation can be applied to the treatment of both effluents, the technique is more efficient in the case of the production of drinking water from surface sources. This behaviour is related to the nature of the natural organic matters (NOM) present in both effluents. [ABSTRACT FROM AUTHOR]

Electrocoagulation (EC) which is characterized by in-situ generation of coagulant and hydroxide flocs with high absorption ability is an environmental-friendly process for treating wastewater with heavy metal ions and toxic organics. In order to get a systematic understanding of EC process, a steady state model considering electrochemical, hydrolysis reaction, mass and momentum transfer was established. The coagulant (Al 3+ ), H + and OH − are generated at the direction of streamline. However, the concentration of these species increases and reaches its maximum near inlet and after that they decrease gradually to a much lower level. We found that there are three areas in EC channel: acid front, base front and buffering area, which has also been found in electro-kinetic remediation. At the direction of streamline, the electro-generated Al 3+ is gradually hydrolyzed to hydroxides. The anionic and cationic hydroxides accumulate in acid front and base front respectively. The insoluble hydroxides will accumulate in buffering area, which could be considered as a trap for hydroxide flocs and pollutants. [ABSTRACT FROM AUTHOR]

Conventional water treatment process is composed of multiple stages, including desalination (salt removal) and pre/post-treatment of desalination to remove particles, chemicals, and other potential foulants for desalination. In this work, we developed a microfluidic proof-of-concept for a single device water treatment system, which removes both salt ions and non-salt contaminants. Our system combines electrocoagulation (EC), a versatile contaminant removal process, and ion concentration polarization (ICP) desalination, which is an electromembrane desalination process. We demonstrated a continuous EC–ICP operation that removed ＞95% of suspended solids and reduced the salinity from brackish range (20 mM NaCl) to a potable level (＜8.6 mM NaCl). We also demonstrated that our system is flexible in terms of the type and concentration of contaminants it can handle. Combining two different electrochemical processes into a single system, we can reduce unnecessary voltage drop by having a shared anode, and achieve both seamless integration and energy efficient operation. Our system will find applications as a small-scale water treatment system, if properly scaled up in the future. [ABSTRACT FROM AUTHOR]

Electrocoagulation (EC) is employed to investigate the energy consumption (EnC) of synthetic wastewater. In order to find the best process conditions, the influence of various parameters including initial pH, initial dye concentration, applied voltage, initial electrolyte concentration, and treatment time are investigated in this study. EnC is considered the main criterion of process evaluation in investigating the effect of the independent variables on the EC process and determining the optimum condition. Evolutionary polynomial regression is combined with a multi-objective genetic algorithm (EPR-MOGA) to present a new, simple and accurate equation for estimating EnC to overcome existing method weaknesses. To survey the influence of the effective variables, six different input combinations are considered. According to the results, EPR-MOGA Model 1 is the most accurate compared to other models, as it has the lowest error indices in predicting EnC (MARE = 0.35, RMSE = 2.33, SI = 0.23 and R² = 0.98). A comparison of EPR-MOGA with reduced quadratic multiple regression methods in terms of feasibility confirms that EPR-MOGA is an effective alternative method. Moreover, the partial derivative sensitivity analysis method is employed to analyze the EnC variation trend according to input variables. [ABSTRACT FROM AUTHOR]

Electrocoagulation process is a new and developing method that has been employed significantly to remove pollutants from wastewater. In this research the electrocoagulation process has been examined for the removal of chemical oxygen demand (COD), turbidity, hardness, and organic matter from greywater. An economical comparison has been implemented between electrocoagulation and coagulation processes near the mining areas. The results demonstrate that the electrode type and operation time have a significant impact on the removal of COD, turbidity, and hardness. The least operating cost to remove organic matters is ~US$ 0.04 m−3for the iron electrode. Since the least operating cost was US$ 0.09 m−3in coagulation process, economically, the electrocoagulation process in comparison with the coagulation process is a more effective process. [ABSTRACT FROM AUTHOR]

The conventional coagulation technique of textile wastewater treatments is plagued with the issue of low removal rate of pollutants and generation of a large quantity of sludge. Recently, electrocoagulation (EC) technique gained immense attention due to its efficiency. The technique involves dissolution of the sacrificial anodes to provide an active metal hydroxide as a strong coagulant that destabilizes and amasses particles and then removes them by precipitation or adsorption. EC process is influenced by operating parameters such as applied current density, electrodes material and configuration, type of electrical connection, pH and conductivity of the solution, and mixing state. Consequently, this work reviewed the major and minor reactions of EC process with operational parameters, design of EC cell, mass transfer studies and modeling, and industrial wastewater applications. The work also includes comparison of EC technique with conventional coagulation and combinations with other techniques. Special emphasis is on removal of pollutants from textile wastewater. Further, the electrical energy supplies and cost analysis are also discussed. Even though several publications have covered EC process recently, no review work has treated the systematic process design and how to minimize the effect of passivation layer deposited on the surface of the electrodes. EC process with rotating electrodes has been recommended to reduce this phenomenon. The effect of electrodes geometry is considered to enhance the conductivity of the cell and reduce energy consumption. The studies of ionic mass transfer were not implemented before special by limiting current method during the EC process. Moreover, no aforementioned studies used computational fluid dynamics modeling to present the mass transfer inside the EC reactor. [ABSTRACT FROM AUTHOR]

The COD removal efficiency from an instant coffee processing wastewater using electrocoagulation was investigated. For this purpose, the response surface methodology was employed, using central composing design to optimize three of the most important operating variables, i.e., electrolysis time, current density and initial pH. The results based upon statistical analysis showed that the quadratic models for COD removal were significant at very low probability value (<0.0001) and high coefficient of determination (R2 = 0.9621) value. The statistical results also indicated that all the three variables and the interaction between initial pH and electrolysis time were significant on COD abatement. The maximum predicted COD removal using the response function reached 93.3% with electrolysis time of 10 min, current density of 108.3 A/m2 and initial pH of 7.0, respectively. The removal efficiency value was agreed well with the experimental value of COD removal (90.4%) under the optimum conditions. [ABSTRACT FROM AUTHOR]

Arsenic, classified as a carcinogen, is being subject to high concern due to its high toxicity especially in drinking water. Electrocoagulation (EC) has displayed a great potential as an effective and environmentally friendly method to remove arsenic from wastewaters. This review summarizes the recent development of arsenic removal in EC process including the effects of primary operating parameters, optimization of the EC performance, as well as the evaluation of EC reactor configurations. Production and characterization of EC products with respect to different electrodes are systematically discussed. Besides, this review sheds light on the debate about the mechanism involved in As(III) oxidation and further explores the arsenic adsorption behavior in EC process. Moreover, the performance of EC and other technologies are compared, and future research needs for arsenic removal in EC process are suggested accordingly. Overall, this review will contribute to deepening the understanding of EC process for arsenic removal and offer useful information to researchers in this field. [ABSTRACT FROM AUTHOR]

Turbidity and chemical oxygen demand (COD) removal efficiencies were analyzed depending on electrode layouts by performing electrocoagulation experiments using horizontal and vertical electrochemical cells. Multiple aluminum plate electrodes were placed into different sections of the electrochemical cells. Removal efficiencies at the horizontal electrochemical cell were always higher than the one’s obtained from the vertical electrochemical cell. But the use of vertical electrochemical cell consumed less energy during the electrocoagulation tests. The highest COD removal efficiencies were 97% and 88% in the horizontal and vertical electrochemical cells, respectively. However, the energy consumption for COD removal in the horizontal electrochemical cell was 47% higher than the energy consumed in the vertical electrochemical cell. [ABSTRACT FROM AUTHOR]

Pretreatment with coupled aluminum electrocoagulation (EC) – microfiltration (MF) successfully mitigated colloidal and organic fouling during nanofiltration (NF) of an inland natural brackish surface water. Natural organic matter (NOM) removal by EC was enhanced due to (i) greater degree of NOM protonation by maintaining a slightly acidic pH during electrolysis, compared with that of minimum aluminum solubility (pH of 5.5 compared to 6.2), (ii) providing sufficient contact time during electrolysis and flocculation by utilizing intermediate current density (10 mA/cm 2 ), and (iii) combination of charge neutralization and sweep coagulation by increasing aluminum dosage. Direct evidence for removal of the hydrophobic fraction of NOM along with a portion of the hydrophilic moieties by EC-MF compared to MF-only was provided by attenuated total reflectance-Fourier transform infrared spectroscopy. NF flux profiles with EC-MF pretreatment of natural saline water were nearly identical to that of a model solution with similar ionic composition with no added NOM suggesting insignificant role of organic fouling. X-ray photoelectron spectroscopy showed trace amounts of CaCO 3 precipitates after EC-MF pretreatment, confirmed by electron microscopy, that caused only minor flux decline. Finally, NF achieves excellent strontium removal as well as other divalent ions and NOM. [ABSTRACT FROM AUTHOR]

In this work a new electrocoagulation reactor with cylindrical geometry using a three-dimensional steel wool anode has been developed. The architecture of the Electrocoagulation reactor is closely related to a filter cartridge, modified in order to contain the electrodes. The complete system includes the Cartridge Type ElectroCoagulation Reactor (CTECR) and its housing. The residence time distribution (RTD) was used as tool to study the flow behavior of the electrolyte within the reactor. The new reactor has been successfully used in the removal of a textile dye (Remazol Red RB 133) working in continuous mode of operation, where the color elimination rate reaches 99%. Moreover, its design allows both an easy replacement of the cartridge when the steel wool anode is consumed, and the collection and storage of the hydrogen generated on the cathode. [ABSTRACT FROM AUTHOR]

A unique electrocoagulation based method enabling the deposition of graphene oxide (GO) films on copper was developed. This method involves two distinct steps, (i) electrocoagulation of GO particles dispersed in aqueous media, induced by copper ions produced at the anode and (ii) deposition of the particles onto the copper anode. Under acidic conditions, GO films with tailorable thicknesses (3–130 μm) were readily deposited on the anode by varying applied voltage and deposition time in a controllable manner. The GO particles exhibited negative zeta-potentials, facilitating deposition on the positive anode. The copper oxidation state in the GO film was confirmed using X-ray photoelectron spectroscopy to be 2+, while its concentration within the GO film was strongly dependent on the applied voltages and deposition time. This new approach can be extended to other metal substrates, opening up new avenues for employing GO in a wide variety of energy and membrane applications. [ABSTRACT FROM AUTHOR]

Suitability of the electrocoagulation (EC) process for the post-treatment of anaerobically treated urban wastewater was assessed, in batch system employing real effluent from an upflow anaerobic sludge blanket (UASB) reactor. Response surface methodology (RSM) was used to optimize three important process parameters, namely current density, electrolysis time and initial pH. At the optimum conditions of pH 7.07, electrolysis time 18.0 min and current density 15.0 mA/cm2, chemical oxygen demand (COD), turbidity and phosphate removal efficiencies observed were 71.0%, 98.5% and >99.9%, respectively, which were very close to the model-predicted values. High removals of suspended solids (SS; 87.5%), biochemical oxygen demand (BOD) (83.3%) and total coliforms (99.994%) were also obtained at the optimum conditions. [ABSTRACT FROM PUBLISHER]

The role of hydrogen peroxide (H2O2) in the electrocoagulation (EC) treatment for removing toxic organic matters in wet-spun acrylic fibers (WAFs) manufacturing effluents was investigated. The addition of H2O2in the EC resulted in electro-Fenton (EF) treatment, which improved the removal of organic pollutants. Biodegradability of the EF-treated effluents was significantly improved over the EF treatment and reached 0.18. In addition, evaluation of the toxicity of the treated effluents using luminous bacteria revealed that the EF treatment resulted in the greater removal of toxic compounds than the EC treatment, with 80.9% decline in the EC50. [ABSTRACT FROM PUBLISHER]

Electrocoagulation (EC) technology using aluminum as sacrificial electrode has been successfully applied to remove the emulsified oil with micron size. This study aimed to employ mass balance measurements to quantify the oil separation between flotation and sedimentation for studying pollutant removal mechanism and then research into deciphering EC, which is novel to emulsified oil demulsification using EC. The effects of current density, stirring speed and surfactant type on oil removal path were investigated. The percentage mass floated was found to increase with current density increase. After electrolysis, the maximum current density, 150 A m −2 , produced the largest pollutant recovery at the surface (approximately 90% of the total mass). In contrast, the mass fraction of oil floated was observed to increase and then decrease with increasing stirring intensity by magnetic stir. Under the same condition, the dramatic mixing, 1000 rpm, transported the less pollutant by floated (only about 63% of the total mass); and yet the gentle mixing of 500 rpm, created the maximum mass floated (approximately 90% of the total mass). For a given current density and stirring intensity, the dominant removal path of emulsified oil is always flotation. Experiments were conducted to determine the optimum operating conditions as current density of 75 A/m 2 and stirring speed of 300 r/min, for maximum removal efficiency of emulsified diesel in bulk solution, approximately 97.3%. Type of surfactant is identified as the key operational parameter influencing which pollutant removal mechanism dominates. Through comparing SDBS, Tween 80, and the mix surfactant with both SDBS and Tween 80, the pollutant fates were found to be various due to different foaming characteristic of these reagent. Ultimately, the emulsified oil in the bulk solution was more difficult to be removed with the more types of surfactant. [ABSTRACT FROM AUTHOR]

Electrocoagulation was investigated for the removal of copper, silicon, manganese, aluminum, iron and zinc as well as sulfate from real mine water. Batch experiments with monopolar iron anode and stainless steel cathode as well as monopolar aluminum anode and stainless steel cathode were conducted separately to identify the best electrocoagulation conditions. The removal efficiency in mine water increased with increasing reaction time and increasing current density and the type of electrodes affected the metals and sulfate removal as could be shown by the adsorption isotherms. Copper and silicon were obeying a Langmuir isotherm with an iron anode, whereas they were following a Freundlich isotherm when an aluminum anode was applied. The aluminum electrode resulted in a higher Langmuir constant q max for all metals, while the iron electrode showed a better efficiency for removing the metals. This might be a result of the higher kinetic rate of iron compared to aluminum. Sulfate removal was better with aluminum electrodes resulting in removal rates of up to 41%, removing up to 5700 mg/L sulfate from the initial sulfate concentrations, whereas iron could only remove 3833 mg/L of sulfate from the real mine water. Furthermore, sulfate removal by aluminum electrode was faster compared to iron electrode. [ABSTRACT FROM AUTHOR]

In this work the optimal operating conditions for removing selected micropollutants (also known as emerging contaminants, ECs) from actual municipal wastewater by graphene adsorption (GA) and simultaneous electrocoagulation/electrofiltration (EC/EF) process, respectively, were first determined and evaluated. Then, performance and mechanisms for the removal of selected phthalates and pharmaceuticals from municipal wastewater simultaneously by the GA and EC/EF process were further assessed. ECs of concern included di-n-butyl phthalate (DnBP), di-(2-ethylhexyl) phthalate (DEHP), acetaminophen (ACE), caffeine (CAF), cefalexin (CLX) and sulfamethoxazole (SMX).It was found that GA plus EC/EF process yielded the following removal efficiencies: DnBP, 89± 2%; DEHP, 85 ±3%; ACE, 99 ±2%; CAF, 94±3%; CLX, 100±0%; and SMX, 98±2%. Carbon adsorption, size exclusion, electrostatic repulsion, electrocoagulation, and electrofiltration were considered as the main mechanisms for the removal of target ECs by the integrated process indicated above. [ABSTRACT FROM AUTHOR]

Iron electrocoagulation (Fe-EC) has been shown to effectively remove arsenic from contaminated groundwater at low cost and has the potential to improve access to safe drinking water for millions of people. Understanding how operating conditions, such as the Fe dosage rate and the O 2 recharge rate, affect arsenic removal at different pH values is crucial to maximize the performance of Fe-EC under economic constraints. In this work, we improved upon an existing computational model to investigate the combined effects of pH, Fe dosage rate, and O 2 recharge rate on arsenic removal in Fe-EC. We showed that the impact of the Fe dosage rate strongly depends on pH and on the O 2 recharge rate, which has important practical implications. We identified the process limiting arsenic removal (As(III) oxidation versus As(V) adsorption) at different pH values, which allowed us to interpret the effect of operating conditions on Fe-EC performance. Finally, we assessed the robustness of the trends predicted by the model, which assumes a constant pH, against lab experiments reproducing more realistic conditions where pH is allowed to drift during treatment as a result of equilibration with atmospheric CO 2 . Our results provide a nuanced understanding of how operating conditions impact arsenic removal by Fe-EC and can inform decisions regarding the operation of this technology in a range of groundwaters. [ABSTRACT FROM AUTHOR]

The present investigation involves an optimization of the electrocoagulation on aqueous organic dye solutions with two different group of operational conditions namely reactor design such as applied voltage, effective surface area, inter electrode distance, stirring speed and nature of the organic dye solutions such as pH, conductivity, dye concentration, temperature. The experiments are focused on the maximum colour and COD removal with minimum energy and electrode consumption. The kinetic study reveals the colour removal efficiency of two organic dye solutions is decreases from 0.142 to 0.026 min − 1 for DG1 and from 0.119 to 0.023 min − 1 for RR2 with increase in pH. Thermodynamic parameter of ΔH and ΔS shows the endothermic nature of adsorption of dyes. Freundlich constant evidenced the adsorption of both dyes over floc surface is spontaneous. The maximum dye removed per unit area of electrode is 26.8 ppm/cm 2 for DG1 and 21.2 ppm/cm 2 for RR2 observed at the 10 cm 2 effective surface area. The FTIR analysis of floc residue, peak values at 3452.56 and 1496.93 cm − 1 of RR2 alone shifted to 3418.31 and 1425.78 cm − 1 in electrocoagulated floc residue suggests the adsorption of RR2 over iron flocs. The peak at 1493.32 cm − 1 supports the presence of azo group in the parent dye structure of DG1 and disappearance of the peak in electrocoagulated flocs residue evidenced the adsorption of partially degraded dyes on electrocoagulated flocs. [ABSTRACT FROM AUTHOR]

Co-existence of arsenic and fluoride in groundwater has raised severe health issues to living being. Thus, the present research has been conducted for simultaneous removal of arsenic and fluoride from synthetic groundwater by using electrocoagulation process with aluminum electrode. Effects of initial pH, current density, run time, inter electrode distance and NaCl concentration over percentage removal of arsenic and fluoride as well as operating cost have been studied. The optimum experimental conditions are found to be initial pH: 7, current density: 10 A/m 2 , run time: 95 min, inter electrode distance: 1 cm, NaCl concentration: 0.71 g/l for removal of 98.51% arsenic (initial concentration: 550 μg/l) and 88.33% fluoride (initial concentration: 12 mg/l). The concentration of arsenic and fluoride in treated water are found to be 8.19 μg/l and 1.4 mg/l, respectively, with an operating cost of 0.357 USD/m 3 treated water. Pseudo first and second order kinetic model of individual and simultaneous arsenic and fluoride removal in electrocoagulation have also been studied. Produced sludge characterization studies also confirm the presence of arsenic in As(III) form, and fluoride in sludge. The present electrocoagulation process is able to reduce the arsenic and fluoride concentration of synthetic as well as real groundwater to below 10 μg/l and 1.5 mg/l, respectively, which are maximum contaminant level of these elements in drinking water according to WHO guidelines. [ABSTRACT FROM AUTHOR]

The performance of electrocoagulation (EC) significantly depends on flocs properties that could be improved through regulating electrochemical parameters. However, little information has been collected to date regarding the relationship between flocs characteristics and electrochemical parameters. In this study, the influences of pH and current density ( j ) were investigated to characterize the flocs generated from EC process with aluminum anode. The results indicated that higher j performed better on HA removal due to a larger Al dosage. A highest efficiency in HA removal by EC process occurred at weak acidic range, where the flocs presented a stronger adsorption ability. Higher j and higher water pH led to a larger flocs size. The EC time to form the largest flocs was consistent with that to reach zero point charge, where surface charge favors the aggregation of Al(OH) 3 precursors to form large flocs. Flocs strength was positively correlated with applied j and negatively correlated with water pH. The flocs generated with low applied j and at low initial pH had a higher value of BET surface area and a more porous surface structure. [ABSTRACT FROM AUTHOR]

Electrocoagulation is usually applied to remove pollutants from the liquid phase, but in this work it is investigated to concentrate pollutants, with the final aim to get a later much more efficient treatment by electrolysis. Results obtained during the treatment of wastes polluted with commercial oxyfluorfen (Fluoxil) show that electrocoagulation exhibits a good efficiency in removing this model nonionic halogenated pesticide. It was observed that the chemicals contained in Fluoxil with higher solubility than oxyfluorfen are less efficiently removed, explaining the lower removal of TOC as compared to that of oxyfluorfen. An improvement in the design of the electrocoagulation was faced by increasing the amount of particles in the reactor, allowing one to deplete the pesticide concentration down to levels 2-log below the inlet concentration. The herbicide is concentrated in a solid phase, from where it can be released to a concentrated waste just by changing the pH. [ABSTRACT FROM AUTHOR]

Electrocoagulation can successfully remove metals from diluted wastewater streams with conventional anode materials, such as aluminium, iron and copper. The disadvantages of conventional electrocoagulation systems (i) are expensive because they require substantial electric energy input, and (ii) electrode materials directly influence electrocoagulation efficiency. Developing an electrocoagulation system with a solar photovoltaic energy source is possible. Using this energy source significantly reduces process costs and exhibit high treatment efficiency when combined with a suitable electrode material. In this study, perforated zinc was tested as a novel anode to remove lead ions from aqueous solutions through electrocoagulation treatment powered by solar photovoltaic. The effects of electrode materials, electrode geometry, energy consumption and sludge production on Pb(II) removal were also investigated. Results demonstrated the superior performance of the perforated zinc electrode with a lead ions removal efficiency of 99.9% achieved within 10 min of treatment at 1.13 mA/cm 2 current density. Morphological, elemental analysis of the electrode surface and formed sludge confirmed that less sludge was generated during Pb(II) removal from simulated wastewater by the proposed electrocoagulation system under the optimal conditions. [ABSTRACT FROM AUTHOR]

The present study reports the wireless electrocoagulation (WEC) based on bipolar electrochemistry where the iron sheets were used as sacrificial bipolar electrodes (BPEs) and two graphite plates served as driving electrodes. Driven by the interfacial potential difference induced by electric field in solution, the iron dissolution started at the anodic pole, achieving the generation of iron coagulant and thus turbidity removal. The total iron concentration produced was found to be more dependent on the geometrical configuration of BPE rather than electrochemical parameters. That is, placing the BPE with the length in parallel to electric field could generate iron concentration of 84.6% higher than that when placed vertically. Besides, increasing the number of BPE from one to three led to the increase in coagulant production by 2.1 times. Moreover, to maximize the voltage drop and minimize the material used, the BPE was designed into different geometrical shapes. The “H-shaped” BPE could achieve almost the same iron concentration as the unmodified BPE even the relative cathode/anode surface area was as low as 0.36. This accounted for efficient coagulant production by saving as great as 40% of the electrode material and cost. The wireless operation can not only solve the problems caused by electrode connection, but also allow arbitrary number of sacrificial BPEs working simultaneously in a very simple setup. In addition, the WEC performance can be easily controlled by the geometrical configuration of BPE. All these factors will be expected to make the electrocoagulation process much easier, more economical and more reliable in water treatment. [ABSTRACT FROM AUTHOR]

Electrocoagulation process (EC) has been the subject of several reviews in the last decade, and is still a very active area of research. Most published works deals with applications for treatment of drinking water and urban, industrial or agricultural wastewaters so as to enhance the simultaneous abatement of soluble and colloidal pollution. These also include contributions to theoretical understanding, electrode materials, operating conditions, reactor design and even techno-economic analysis. Even though, the numerous advantages reported in the literature, and the pros and cons of EC in comparison to alternative processes, its industrial application is not yet considered as an established wastewater technology because of the lack of systematic models for reactor scale-up. This paper presents a comprehensive review on its development and design. The most recent advances on EC reactor modeling are summarized with special emphasis on four major issues that still constitute the cornerstone of EC: the theoretical understanding of mechanisms governing pollution abatement, modeling approaches, CFD simulations, and techno-economic optimization. Finally, outlooks for future research and developments are suggested. [ABSTRACT FROM AUTHOR]

Electrocoagulation is a simple and efficient treatment method involving the electrodissolution of sacrificial anodes and formation of hydroxo-metal products as coagulants, while the simultaneous production of hydrogen at the cathode facilitates the pollutant removal by flotation. Oil is one of the most important hydrocarbon products in the modern world. It can cause environmental pollution during various stages of production, transportation, refining and use. Electrocoagulation treatment is particularly effective for destabilization of oil-in-water emulsions by neutralizing charges and bonding oil pollutants to generated flocs and hydrogen bubbles. The development of electrocoagulation technologies provided a promising alternative for oil removal from wastewater. This paper presents a review of emerging electrochemical technologies used for treating oil-containing wastewater. It includes a brief description of the oily wastewater origin and characteristics. The treatment processes developed so far for oily wastewater and the electrocoagulation mechanisms are also introduced. This paper summarizes the current applications of electrocoagulation for oil removal from wastewater. The factors that influence the electrocoagulation treatment efficiencies as well as the process optimization and modeling studies are discussed. The state-of-the-art and development trends of electrocoagulation process for oil removal are further introduced. [ABSTRACT FROM AUTHOR]

Electrocoagulation (EC) was employed to treat residual organic matter from a landfill leachate pretreated by an aerated bio-filter system. Organic matter (humic acids (HA), fulvic acids (FA) and hydrophilic compounds (Hyl)) was fractionated using DAX-8 resin in order to estimate the efficiency of EC on each fraction. Initial characterization of the bio-filtrated landfill leachate showed that humic substances (HA + FA) represented nearly 90% of TOC. The effects of current densities, type of anode (Aluminum versus iron), and treatment time on the performance of COD removal were investigated. The best COD removal performances were recorded at a current density ranging between 8.0 and 10 mA cm −2 during 20 min of treatment time. Under these conditions, 70% and 65% of COD were removed using aluminum and iron electrodes, respectively. The fractionating of organic matter after EC treatment revealed that HA was completely removed using either aluminum or iron anode. However, FA and Hyl fractions were partially removed, with the percentages varying from 57 to 60% and 37–46%, respectively. FA and Hyl removal were quite similar using either aluminum or iron anode. Likewise, a significant decrease in 254-nm absorbance was recorded (UV 254 removal of 79–80%) using either type of anode. These results proved that EC is a suitable and efficient approach for treating the residual refractory organic matter from a landfill leachate previously treated by a biological system. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are an important class of water pollutants because of their known ecological and human toxicity. Electrocoagulation (EC) is a promising technology for mitigating industrial wastewater pollution, but the removal and transformation of PAHs during EC treatment has not yet been understood. Therefore, a paper-making wastewater effluent (PMWW) was employed in this study to investigate the relationship between PAHs’ removal and transformation during EC treatment. The results show that 86% of PAHs were effectively removed not only by the electro-oxidation reactions, but also by adsorption onto Fe hydroxide flocs. The removal and transformation of PAHs were related to the number of rings in their structures. Some PAHs composed of two aromatic rings (e.g., naphthaline and dimethylnaphthalene) were produced from humic acid-like and fulvic acid-like organics in PMWW, while PAHs with three to four rings were degraded, thus being removed efficiently. Therefore, PAH transformation during EC treatment exerted double-sided effects on the removal of PAHs; the net effect appeared to be positive. Overall, this study revealed the existence and importance of PAH transformation during EC treatment and provided useful guidance for pulp and paper mills to improve the design and operation of wastewater treatment facilities. [ABSTRACT FROM AUTHOR]

The present study dealt with treatment performances and operating cost of real metalworking fluid wastewater (MWFW) using chemical coagulation (CC) and electrocoagulation (EC) processes. The optimum coagulant dosage for COD and TOC removal efficiencies from the MWFW was determined with varying concentrations of alum, aluminium chloride, ferric sulphate, and ferric chloride. COD and TOC removal efficiencies in the coagulant dosage range of 50-1000 mg/L were obtained as 65-97% and 49-81% for alum, 48-96% and 38-80% for aluminium chloride, 43-92% and 36-76% for ferric sulphate, and 55-93% and 41-77% for ferric chloride, respectively. The aluminium-based coagulants at a pH of 7.5 showed better performances than ferric-based coagulants in terms of COD and TOC removals. COD and TOC removal efficiencies from the MWFW in the EC process were 93% and 80% for Al electrode at a pH of 5, 80 A/m² and 25 min, and 93% and 82% for Fe electrode at a pH of 7, 80 A/m² and 25 min, respectively. Operating costs at the optimum conditions were calculated to be 1.190 US $/m³ for Al and 1.813 US $/m³ for Fe electrodes, respectively. Alum in chemical coagulation process provided a lower operating cost (0.12 US $/m³) as compared with the EC process using Al electrode (1.19 US $/m3). The results demonstrated that both investigated treatment processes were effective to treat wastewater from a metalworking plant. [ABSTRACT FROM AUTHOR]

Electrocoagulation is an effective electrochemical approach for the treatment of different types of contaminated water and has received considerable attention in recent years due its high efficiency in dealing with numerous stubborn pollutants. It has been successful in dealing with organic and inorganic contaminants with negligible or almost no generation of by-product wastes. During the past decade, vast amount of research has been devoted to utilizing electrocoagulation for the treatment of several types of wastewater, ranging from polluted groundwater to highly contaminated refinery wastewater. This paper offers a comprehensive review of recent literature that has been dedicated to utilizing electrocoagulation for water treatment, focusing on current successes on specific applications in water and wastewater treatment, as well as potentials for future applications. The paper examines such aspects as theory, potential applications, current challenges, recent developments as well as economical concerns associated with the technology. Most of the recent EC research has been focusing on pollutant-specific evaluation without paying attention to cell design, process modeling or industrial applications. This review attempts to highlight the main achievements in the area and outlines the major shortcomings with recommendations for promising research options that can enhance the technology and broaden its range of applications. [ABSTRACT FROM AUTHOR]

A combined two steps electrocoagulation–flocculation was designed to remove COD, BOD 5 , TSS, nitrate (NO 3 ), nitrogen (N), phosphate (P), and fecal coliform (FC) from urban wastewater. The possibility of adding a natural flocculant extracted from plant material, Spineless Prickly Pear, Opuntia ficus Indica , juice (OFIJ), by comparing it with an industrial grade flocculant as anionic polyacrylamide (APAM), in the process of electrocoagulation–flocculation (ECF) was performed. The electrocoagulation (EC) reactor was tested in two different sequences (before and after the flocculation unit). The effect of several operational parameters, such as: current density, reaction time, flocculant dose, specific amount of dissolved electrodes and initial pH, on the removal efficiency of major pollutants was determined. The application of ECF process under optimal conditions, such as: current density (200 A/m 2 ), reaction time (30 min), flocculant dose (6 ml/l), initial pH (7.4) and specific amount of dissolved electrodes (0.2 kg/m 3 ) allows to achieve these promised removal efficiencies: 85%COD, 84%BOD 5 , 94%TSS, 63%N, 73%NO 3 and 99%P. Moreover, it is of interest to note that duration of 10 min is sufficient to remove 99% of FC from the studied urban wastewater. These operating conditions of ECF led to reducing specific energy consumption from 6 kWh/kg COD and 0.6 kWh/kg P (EC process) to 5 kWh/kg COD and 0.5 kWh/kg P, respectively. A comparative operating cost analysis was also given and it was found that ECF performance requires 0.7 $/kg of COD and 0.3 $/kg of P removed vs. 0.9 $/kg COD and 0.35 $/kg P for EC process. [ABSTRACT FROM AUTHOR]

In this study, an electrocoagulation reactor (ECR) and photocatalytic reactor (PCR) were tested to understand the performance of combined electrocoagulation and photocatalytic-degradation of olive washing wastewater (OWW). The effects of initial pH (6.0, 6.9, 8.0, 9.0), applied voltage (10.0, 12.5, 15.0 V), and operating time (30, 60, 90, 120 min) were investigated in the electrocoagulation reactor when aluminum electrodes were used as both anode and cathode. The pH, conductivity, color, chemical oxygen demand (COD), and phenol were measured versus time to determine the efficiency of the ECR and PCR process. It was observed that electrocoagulation as a single treatment process supplied the COD removal of 62.5%, color removal of 98.1%, and total phenol removal of 87% at optimum conditions as pH 6.9, applied voltage of 12.5 V, and operating time of 120 min. Moreover, final pH and conductivity were 7.7 and 980 µS/cm, respectively. On the other hand, the effect of semiconductor catalyst type (TiO2 and ZnO) and loading (1, 2, 3 g/L) were tested using PCR as a standalone technique. It was found that photocatalytic degradation as a single treatment process when using 1 g/L ZnO achieved the COD removal of 46%, color removal of 99% with a total phenol removal of 41% at optimum conditions. Final pH and conductivity were 6.2 and 915 µS/cm, respectively. Among semiconductor catalysts, TiO2 and ZnO performed identical efficiencies for both COD and total phenol removal. Moreover, combination in which electrochemical degradation was employed as a pre-treatment to the photocatalytic degradation process obtained high COD removal of 88% and total phenol, as well as color removal of 100% for the OWW. The electrochemical treatment alone was not effective, but in combination with the photocatalytic process, led to a high-quality effluent. Finally, sludge collected from the electrocoagulation process was characterized by attenuated total reflection Fourier transform infrared and X-ray powder diffraction analyses. [ABSTRACT FROM AUTHOR]

The present study focused on the removal of ciprofloxacin from hospital wastewater using electrocoagulation (EC) process by iron electrode and the kinetic and isotherms of adsorption were investigated. Response surface methodology (RSM) was used to evaluate the main effects of parameters, their simultaneous interactions and quadratic effect to achieve the optimum condition for EC process. The maximum removal rate was achieved at the current density of 15 mA·cm − 2 , initial CIP concentration of 60 mg·L − 1 , pH 7.5, inter-electrode distance 1.58 cm and electrolyte dose of 0.07 M NaCl within the equilibrium time of 20 min. The obtained experimental results are in good accordance with the Langmuir isotherm model for CIP adsorption on iron hydroxide by predicting the maximum adsorption capacity of 476.19 mg·g − 1 . The predicted model for treatment of synthetic wastewater is in satisfactory agreement with real hospital wastewater treatment. First and second order kinetic models were studied to figure out the exact mechanism of the CIP removal using EC process. The obtained results revealed that the second order kinetic model best fitted the experimental results and suggested that the chemisorption mechanism controlled the adsorption of CIP. Under the optimal conditions of EC process, electrode consumption (ELC) and electrical energy consumption (EEC) were found to be 0.0625 g during a single run and 0.522 kWh·m − 3 , respectively. [ABSTRACT FROM AUTHOR]

This paper deals with the ability of electrocoagulation (EC) to remove simultaneously COD and chromium from a real chrome tanning wastewater in a batch stirred electro-coagulation cell provided with two aluminium-based electrodes (aluminium/copper/magnesium alloy and pure aluminium). Effects of operating time, current density and initial concentration of Cr(III) and COD have been investigated. The concentrations of pollutants have been successfully reduced to environmentally acceptable levels even if the concentrated effluent requires a long time of treatment of around 6 h with a 400 A/m 2 current density. The aluminium alloy was found to be more efficient than pure aluminium for removal of COD and chromium. Dilution of the waste has been tested for treatment: high abatement levels could be obtained with shorter time of treatment and lower current densities. Energy consumption of the electrocoagulation process was also discussed. The dilution by half of the concentrated waste leads to a higher abatement performance of both COD and chromium with the best energy efficiency. [ABSTRACT FROM AUTHOR]

The unique electrocoagulator proposed in this study is highly efficient at removing Ni-EDTA, providing a potential remediation option for wastewater containing lower concentrations of Ni-EDTA (Ni ≤ 10 mg L −1 ). In the electrocoagulation (EC) system, cylindrical graphite was used as a cathode, and a packed-bed formed from iron scraps was used as an anode. The results showed that the removal of Ni-EDTA increased with the application of current and favoured acidic conditions. We also found that the iron scrap packed-bed anode was superior in its treatment ability and specific energy consumption (SECS) compared with the iron rod anode. In addition, the packed density and temperature had a large influence on the energy consumption (ECS). Over 94.3% of Ni and 95.8% of TOC were removed when conducting the EC treatment at an applied current of 0.5 A, initial pH of 3, air-purged rate 0.2 L min −1 , anode packed density of 400 kg m −3 temperature of 313 K and time of 30 min. SEM analysis of the iron scraps indicated that the specific area of the anode increased after the EC. The XRD analysis of flocs produced during EC revealed that hematite (α-Fe 2 O 3 ) and magnetite (Fe 3 O 4 ) were the main by-products under aerobic and anoxic conditions, respectively. A kinetic study demonstrated that the removal of Ni-EDTA followed a first-order model with the current parameters. Moreover, the removal efficiency of real wastewater was essentially consistent with that of synthetic wastewater. [ABSTRACT FROM AUTHOR]

Effects of electrolysis duration, initial phosphate concentrations and supporting electrolyte concentrations on the phosphate removal efficiency by electrocoagulation using either aluminum or iron electrodes were investigated in this study. All experiments were performed in a batch electrochemical reactor on synthetically prepared wastewater of the initial volume 0.2 L. The results indicate that increase of initial phosphate concentration has reduced removal rate, and by increasing the electrolysis duration removal efficiency increases. It was found that the aluminum electrode has higher removal efficiency (98.9%) compared to the iron electrode (93.5%) for 40 minutes of treatment (pH=3, j=1 mA/cm2, γ0=50 mg/L P-PO4). The addition of supporting electrolyte ( NaCl=0.25 g/L) is achieved removal efficiency of 50.2% for Fe and 52.1% fo Al electrode in only 10 minutes of treatment, respectively [ABSTRACT FROM AUTHOR]

In the present study, an electrocoagulation process was applied to treat saline oilfield-produced water. The kinetics of simultaneous heavy metal and oil removal in the saline environment under different conditions including four-electrode materials of copper, zinc, iron, and aluminum, aeration and agitation rate, oil content, and salinity was investigated. The nature of the electro-generated species and possible abatement mechanisms were explored and compared by using FE-SEM/EDS, FTIR, XRD, and BET analyses. At low and high salinities, cadmium adsorption followed Langmuir and Freundlich models, suggesting the transformation of identical adsorption sites to heterogeneous ones. Cadmium removal efficiencies of 99/73% were obtained at low/high salinity with iron and 99.9 and 82% using copper and zinc electrodes in a saline environment. The cadmium adsorption capacity of different anode materials exhibited the order of copper > zinc > iron > aluminum. The adsorption capacity was considerably reduced in saline condition due to more crystalline structure and lower surface area and porosity of the particles while it was enhanced by the oil, caused by structural changes including more uniform pores, the elevated surface area, and porosity. The COD removal yield of 89% for low salinity and 80/73% at high salinity with/without aeration were achieved by iron. The highest COD removal yield of about 95% was achieved by the aluminum electrodes, compared to 85 and 87% for copper and zinc electrodes. The main removal mechanisms were outer- and inner-sphere complexation, and surface precipitation. [ABSTRACT FROM AUTHOR]