This paper investigates the effect of electrocoagulation (EC) process on the removal of suspended solids (SS) from wastewater. In a batch electrochemical cell experimental set up, two monopolar iron (Fe) plate were used as electrodes (anodes and cathodes). Synthetic wastewater, made of milk powder with concentration of 700 mg/L, was treated using 1M HCl for pH adjustment before it was used as electrolyte. Preliminary results show that the EC process is able to enhance the removal of suspended solid, turbidity and carbon oxygen demand in wastewater. The removal rates of those elements were increase with treatment time. Abstrak: Tujuan kertas kerja ini adalah untuk menyelidiki kesan proses elektrokoagulasi (EC) bagi mengurangkan pepejal terampai dari air sisa. Di dalam ujikaji berskala makmal menggunakan sel elektrokimia jujukan, dua keping plat besi (Fe) monopolar telah digunakan sebagai elektrod (anod dan katod). Susu tepung dengan kepekatan 700 mg/L, telah diolah menggunakan HCl 1 M sebagai pengawal pH dan elektrolit. Keputusan awal mendapati bahawa teknologi EC mampu meningkatkan penyingkiran pepejal terampai, kekeruhan dan COD. Kadar penyingkiran ini meningkat seiring dengan tempoh pengolahan dan tempoh pemendapan.
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... Magnetic treatment of water was first patented by Vermeiren in Belgium in 1945, and he is recognized as the discoverer of the fact that magnetic fields affect water. Magnetic treatment of water is an attractively simple approach by which the water to be treated flows through a magnetic field, and consequently changes some of its physicochemical properties (Othman et al., 2001; Sohaili et al., 2004; Ni'am et al., 2006). ...
... In the preliminary research, the authors have investigated the effect of EC with iron (Fe) bar and plate electrodes in the batch experiment (Ni'am et al., 2005, 2007a,b and 2008; Othman et al., 2006). The results of a combined magnetic field and EC with Fe bar electrodes shown that the SS and turbidity removal are as high as 91.4 % and 85.5 % with the combined process, while for EC process is as high as 88 % and 72.1 % (Ni'am et al., 2005). ...
Design of experiments (DOE) is one of the statistical method that is used as a tool to enhance and improve experimental quality. The changes to the variables of a process or system is supposed to give the optimal result (response) and quite satisfactory. Experimental design can defined as a test or series of test series by varying the input variables (factors) of a process that can known to cause changes in output (response). This paper presents the results of experimental design of wastewater treatment by electrocoagulation (EC) technique. The objectives of this study were to investigate the suitability of magnetic fields and electrocoagulation technologies for the treatment of wastewater in enhancing removal of suspended solids and its sedimentation. A combined magnet and electrocoagulation (EC) technology were designed to increase settling velocity and to enhance suspended solid removal efficiencies from wastewater samples. In this experiment, a synthetic wastewater samples were prepared by mixing 700 mg of the milk powder in one litre of water and treated by using an acidic buffer solution. The monopolar iron (Fe) plate anodes and cathodes were employed as electrodes. Direct current was varied in a range of between 0.5 and 1.1 A, and flowrate in a range of between 1.00 to 3.50 mL/s. One permanent magnets namely AlNiCo with a magnetic strength of 0.16T was used in this experiment. The results show that the magnetic field and the flowrate have major influences on suspended solids removal. The efficiency removals of suspended solids, turbidity and COD removal efficiencies at optimum conditions were found to be more than 85%, 95%, and 75%, respectively.
... With an iron anode, Fe(OH) 2 or Fe(OH) 3 is formed at the anode. Reaction mechanism of iron electrode at the anode and cathode are reported by many authors (Mollah et al., 2004;Othman et al., 2006;Babu et al., 2007;Murthy and Raina, 2008 According to Larue and Vorobiev (2003), the generation of iron hydroxides Fe(OH) n is followed by an electrophoretic concentration of colloids (usually negatively charged) in the region close to the anode. The produced ferrous ions hydrolyze to form monomeric hydroxide ions and polymeric hydroxide complexes that depend on the pH of the solution. ...
... The increase of pH at acidic condition was attributed to hydrogen evolution at cathodes (Abuzaid et al., 1998). Generally, the pH of the medium changes during the process (Othman et al., 2006;Yildız et al., 2008). However, the value of pH remained within the allowable limits ( Table 2). ...
Growing water scarcity in Pakistan is compelling people to use the treated wastewater at least for landscape irrigation and plantation to augment available water resources. In the present study, a laboratory scale electrocoagulation (EC) process was utilized to treat the raw wastewater in order to bring the quality up to the international wastewater reuse standards. Effect of various operating parameters such as operating time, current density and inter-electrode spacing was evaluated to achieve the maximum possible treatment efficiency. It was found that the application of 24.7 mA/cm 2 current density with an inter-electrode spacing of 5 cm may provide 91.8%, 77.2% and 68.5% removal in turbidity, COD and TSS within 30 minutes of EC treatment. The quality of treated wastewater was compared with various international standards/guidelines for wastewater reuse. It was found that the studied parameters such as BOD, COD, TDS, TSS, turbidity, NO 3 -N, NH 3 -N, chloride, Na + , Ca 2+ , Mg 2+ , sulfate, total phosphorus, electrical conductivity Oil and Grease (O & G) and total coliform (TC) were within allowable limits. Electrical conductivity, TDS and Sodium Adsorption Ratio (SAR) are mainly used for the determination of wastewater suitability for safe irrigation. Their values do not exceed the international wastewater reuse standards. The study shows that the raw wastewater generated at the study site after EC treatment is safe for landscape irrigation and plantation.
... Previous studies showed that initial pH has a considerable effect on the efficiency of the electrocoagulation process for removal of organic pollutants (Lakshmi & Sivashanmugam, 2013). Generally, the pH of the medium changes during the process according to Othman et al., (2006), Yildız et al., 2008. However, the value of pH remained within the allowable limits. ...
...  Cathode material is usually stainless steel, except copper which was used by Tsai et al.  and titanium used by Moraes and Bertazzoli.  While Othman et al.  used two monopolar Fe plates as electrodes (anodes and cathodes). Tsai et al.  employed Al and Fe (anodes) to simultaneously utilize electrocoagulation, which is responsible for the removal of organics with high molecular weight. ...
This study investigated the effects of different parameters on the removal efficiencies of organic and inorganic pollutants in landfill leachate treatment by electrolysis. Different parameters were considered such as the electric potential (e.g., 24, 40 and 60 V), hydraulic retention time (HRT) (e.g., 40, 60, 80, 100 and 120 min), sodium chloride (NaCl) concentration (e.g., 1, 3, 5 and 7%), pH (e.g., 3, 7 and 9), electrodes materials [e.g., aluminum (Al) and iron (Fe)] and distance between electrodes (e.g., 1, 2 and 3 cm). The best operational condition of electrolysis was then recommended. The electric potential of 60 V with HRT of 120 min at 5% of NaCl solution using Al as anode and Fe as cathode (kept at a distance of 3 cm) was the most efficient condition which increased the removal efficiencies of various parameters such as turbidity, salinity, total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD) and heavy metals (e.g., Zn and Mn). The higher removal percentages of many parameters, especially COD (94%) and Mn (93%) indicated that the electrolysis is an efficient technique for multi-pollutants (e.g., organic, inorganic and heavy metals) removal from the landfill leachate.
... With iron anode is used, Fe(OH) 2 or Fe(OH) 3 is formed. Reaction mechanism of iron electrode at the anode and cathode are reported by many authors : The generation of iron hydroxides Fe(OH)n is followed by an increase in the concentration of colloids (usually negatively charged) in the region close to the anode . The produced ferrous ions hydrolyze to form monomeric hydroxide ions and polymeric hydroxide complexes that depend on the pH of the solution. ...
... Colloidal particles during electrocoagulation process will destabilized floc-forming larger floc. The formation of H 2 gas at the cathode causes shinking floc, resulting in the accumulation of floccontaining gas at the surface of the water in the form of a layer of sludge . ...
Stockpile wastewater consisted of ferrous metal, manganese metal and total suspended solid (TSS). In addition, it also has high acidity (pH) which is possibly harmful to the environment. This research objectives were to reduce ferrous and manganese metal in coal stockpile wastewater using electrocoagulation technique using aluminum electrode with variation in electrics current and processing time. The most effective conditions in reducing ferrous and manganese concentrations with electric current of ± 2.5 A in 90 minutes. Effectivity in ferrous and manganese metal reduction was 98.7% and 99.6%, respectively. The final concentration of ferrous and manganese metal was 0.08 mg/L and 0.01 mg/L respectively. Optimum concentration of TSS reduction was 83.7% with the final concentration of 72 mg/L. The wastewater pH value became 7,1. Finally, the results demonstrated that the electrocoagulation process using aluminium electrode is a reliable technique for removal of pollutants from coal stockpile wastewater.
... Two electrodes of iron with surface area of 20 cm 2 . The separation between the anode and the cathode was kept at 5 cm (Fadil Othman et al., 2006). The solution in the reactor was stirred by a magnetic plate stirrer with Teflon bar at a rotating velocity of 500 rpm (HP-3000). ...
This study has been carried out to determine the feasibility of COD adsorption on iron
coagulant by EC process, and to find a mathematical model using kinetic isotherms.
Experiments were carried out to treat a high strength wastewater of textile industry
located in Al-Hilla-Iraq using a batchwise mode. A well-rounded range of current
density was tested and the COD removal percent has reached a maximum value of 85.2
under c.d. of 20mA/cm2. It was attempted to fit the experimental data with the popular
adsorption isotherms Langmuir, Freundlich and Temkin, hense the mechanism of
adsorption with the effect of individual parameters on the efficiency of
electrocoagulation have been critically examined. Two well-known coagulant
mechanisms were modeled with the kinetic equations utilizing the result from
experiments relative to EC of COD removal for five set of experiments. It has been
found from the present analysis that the adsorption isotherm with iron (II) and iron
(III) hydroxides combined to generate hydroxo cationic-anionic complex of green rust
mechanism, can be described by Langmuir isotherm equation which gives a preferable
fit of experimental data than the Freundlich and Temkin isotherm model equations.
... With an iron anode, Fe(OH) 2 or Fe(OH) 3 is formed at the anode. The reaction mechanism of the iron electrode at the anode and cathode has been reported by many authors1213141516. ...
Treatment of textile wastewater by the electrocoagulation (EC) process is being investigated by this experimental study. The objective of this experiment is to observe the efficiency of the EC process in removing chemical oxygen demand (COD) and turbidity. In this experiment an iron electrode is used in the EC process, and different working parameters such as pH, current density and operating time were studied in an attempt to achieve a higher removal capacity. The results show that the maximum COD removal occurred at neutral pH at operating time 30 min. COD and turbidity removal reaches at maximum, with optimum consumption of electrodes, between current density 85–95 A/m2, and only trace amounts of metals were determined in the EC treated effluent.
This study was to evaluate technical feasibility of the electro-flotation
method as a primary treatment unit in wastewater treatment system at
cat-fish processing enterprises. Four experiments were carried out to
select suitable operational parameters for electro-flotation unit. The
results at the lab-scale model operated at 45o inclined angle electrode,
486 cm2 effective electrode area, 1 cm electrodes distance, and 30
minutes hydraulic retention time showed that the removal efficiency of
SS, COD, BOD, TKN, Ptotal were 83.2%; 76.8%; 68.28%; 66.92% and
71.36%, respectively. The effluent from electro-flotation process met
the criteria of wastewater loaded to further biological treatment unit.
In spite of abundant literature on the topic, the efficiency of electrocoagulation for a specific effluent cannot be predicted in advance. Prior to designing an industrial wastewater treatment unit, preliminary treatment tests have to be done using different soluble oil wastes with a very high chemical oxygen demand (COD). The influence of various parameters can then be assessed. Coagulant dose, linked to the electrical charge passed and the nature of the waste, seem to be the controlling parameters of process efficiency. The results obtained at the laboratory-scale have been confirmed in a small pilot cell, and an industrial unit has been designed. A preliminary economic study shows that electrocoagulation may be competitive with current treatment technologies. From knowledge gained at bench-scale, we concluded that electrocoagulation appears to be a suitable process for treatment of soluble oily wastes with high COD.
Treatment of saline wastewaters by electrochemical method is investigated in this paper. Experiments were conducted to examine the effects of the operating conditions, such as the pH, initial phenol concentration, salinity, current density, temperature and addition of small amounts of H2O2 on the COD removal efficiency. Possible optimum ranges for these operating variables are experimentally determined. The electrochemical method is found to be quite effective for dealing with the saline wastewaters with salinity of up to 3.5 w/w%. Two kinetic models were also employed to represent the electrochemical treatment process. The experimental data allow determination of the kinetic parameters by the least squares curve fitting principle. The correlation of these two kinetic models to the experimental data is compared.
This paper reviews the development, design and applications of electrochemical technologies in water and wastewater treatment. Particular focus was given to electrodeposition, electrocoagulation (EC), electroflotation (EF) and electrooxidation. Over 300 related publications were reviewed with 221 cited or analyzed. Electrodeposition is effective in recover heavy metals from wastewater streams. It is considered as an established technology with possible further development in the improvement of space-time yield. EC has been in use for water production or wastewater treatment. It is finding more applications using either aluminum, iron or the hybrid Al/Fe electrodes. The separation of the flocculated sludge from the treated water can be accomplished by using EF. The EF technology is effective in removing colloidal particles, oil & grease, as well as organic pollutants. It is proven to perform better than either dissolved air flotation, sedimentation, impeller flotation (IF). The newly developed stable and active electrodes for oxygen evolution would definitely boost the adoption of this technology. Electrooxidation is finding its application in wastewater treatment in combination with other technologies. It is effective in degrading the refractory pollutants on the surface of a few electrodes. Titanium-based boron-doped diamond film electrodes (Ti/BDD) show high activity and give reasonable stability. Its industrial application calls for the production of Ti/BDD anode in large size at reasonable cost and durability.
The characteristics of restaurant wastewater were investigated. High oil and grease contents were detected. Electrocoagulation was used to treat this type of wastewater. Different electrode materials and operational conditions were examined. Aluminum was preferred to iron. Charge loading was found to be the only variable that affected the treatment efficiency significantly. The optimum charge loading and current density were 1.67–9.95 F/m3 wastewater and 30–80 A/m2 depending on the wastewater tested. The removal efficiency of oil and grease exceeded 94% for all wastewaters tested. The experimental results also show that the electrocoagulation can neutralize wastewater pH. Several mechanisms associated with pH variation are proposed.
The goal of coagulation of fine disperse latex particles of suspensions by dosing with iron ions is to enhance suspension clarification, promote sedimentation and improve their filterability. Two kinds of iron dosing were studied; by directly adding iron chloride or iron sulphate to suspensions or by electrolytic decomposition of iron electrodes (electrocoagulation process, EC). The chemical and electrical processes were examined by varying the pH value and the iron ions concentration in order to determine the optimal operating conditions. To minimise the energy consumption in EC, the suspension conductivity and the current density were varied. This paper shows that flocs in EC-treated suspensions had a higher density and tended to be larger than flocs formed in suspensions dosed with iron chloride or iron sulphate. The kinetics of settling and filtration of EC-treated suspensions were accelerated, demonstrating the interest of EC as an alternative to chemical conditioning.
The decolorization of orange II by the D.C. electrocoagulation (EC) method has been studied. In the EC of orange II, the effects of initial pH, rate of stirring, concentration of dye, electrodes distance, current density, water temperature, etc were tested. The optimum operating range for each of these operating variables was experimentally determined. The experimental results revealed that the color of orange II in aqueous phase was effectively removed (>98%) and also the chemical oxygen demand (COD) reduced (>84%), when iron was used as sacrificial anode and the concentration of orange II was <200 ppm. The bach experimental results were assessed in terms of color and COD reduction. The optimum current density was 34.62 A/m2 for effectively removing of orange II. The EC method is found to be quite effective in removing of orange II. This method can neutralize solution pH. In this project desorbed compounds are separated and structures of them are identified and another mechanism for removal of orange II is proposed.
Electrocoagulation is an electrochemical wastewater treatment technology that is currently experiencing both increased popularity and considerable technical improvements. There has been relatively little effort to better understand the fundamental mechanisms of the processes, particularly those that could provide design parameters to optimize the performances of this relatively simple and inexpensive technique. In a research programme to delineate the mechanisms of the fundamental processes involved in, the authors have realized that the technology has been insufficiently reviewed with emphasis on the fundamentals and their relationship to the performance of this technology. This paper presents an in-depth discussion and consideration of the factors that need to be addressed for optimum performance of this technology. Recent improvements of this technique and the theoretical model studies are also reviewed.
Although electrocoagulation is an evolving technology that is being effectively applied today for wastewater treatment, the paucity of scientific understanding of the complex chemical and physical processes involved is limiting future design and hindering progress. The objective of this review through a survey of the literature is to bring the chemistry and physical processes involved into perspective and to focus attention on those areas critically needing research.
Treatment of textile wastewaters by electrocoagulation using iron and of aluminum electrode materials has been investigated in this paper. The effects of relevant wastewater characteristics such as conductivity and pH, and important process variables such as current density and operating time on the chemical oxygen demand (COD) and turbidity removal efficiencies have been explored. Furthermore, the electrode and energy consumptions for each electrode have been calculated. The results show that iron is superior to aluminum as sacrificial electrode material, from COD removal efficiency and energy consumption points.
This study was performed to investigate the variables that influence the efficiency of decolorization of a solution containing an azo dye (Acid Red 14) by electrocoagulation (EC) in order to compare the efficiency of different electrode connections for color removal. Current density, time of electrolysis, interelectrode distance, and pH of the solution were the variables that most influenced color removal. Initially, a simple electrochemical cell was prepared with an anode and a cathode. Then the effect of each variable was studied separately using synthetic wastewater in a batch mode. The efficiency of the method tested was determined by measurement of color removal and reduction of Chemical Oxygen Demand (COD). For dye solutions with COD of approximately 30 ppm and dye concentrations less than 150 ppm, high color removal (93%) was obtained when the pH ranged from 6 to 9, time of electrolysis was approximately 4 min, current density was approximately 80 A/m2, the temperature was approximately 300 K, and interelectrode distance was 1 cm. During the EC process under these conditions, the COD decreased by more than 85%. In the second series of experiment, the efficiency of EC cells with monopolar electrodes in series and parallel connections and an EC cell with bipolar electrodes were compared with results using a simple electrochemical cell. The experimental results showed that an EC cell with several electrodes was more effective than a simple electrochemical cell in color removal. The results also showed that an EC cell with monopolar electrodes had a higher color removal efficiency than an EC cell with bipolar electrodes. Furthermore, within an EC cell, the series connection of the monopolar electrodes was more effective for the treatment process than the parallel connection in color removal.