Recent Applications of Electrocoagulation in Treatment of Water and Wastewater—A Review
14 May 2013-Green and Sustainable Chemistry (Scientific Research Publishing)-Vol. 3, Iss: 2, pp 89-121
TL;DR: In this article, the authors present an overview of the optimum process conditions (treatment times, current densities, and initial pH) and removal efficiencies (mostly high) achieved for the EC applications discussed.
Abstract: During the last two decades, and particularly during the last few years, the environmental sector has shown a largely growing interest in the treatment of different types of water and wastewater by electrocoagulation (EC). The aim of this work was to review studies, conducted mainly during 2008-2011, on the wide and versatile range of feasible EC applications employed in the purification of different types of water and wastewater. The EC applications discussed here were divided into 7 following categories: tannery, textile and colored wastewater; pulp and paper industry wastewater; oily wastewater; food industry wastewater; other types of industrial wastewater; surface water as well as model water and wastewater containing heavy metals, nutrients, cyanide and other elements and ions. In addition, this paper presents an overview of the optimum process conditions (treatment times, current densities, and initial pH) and removal efficiencies (mostly high) achieved for the EC applications discussed. In the vast majority of the studies discussed in this review, the aforementioned values were found to be in the range of 5 - 60 min (typically less than 30 min), 10 - 150 A/m 2 and near neutral pH, respectively. Both operating costs and electrical energy consumption values were found to vary greatly depending on the type of solution being treated, being between 0.0047 - 6.74 €/m 3 and 0.002 - 58.0 kWh/m 3 , but in general they were rather low (typically around 0.1 - 1.0 €/m 3 and 0.4 - 4.0 kWh/m 3
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TL;DR: In this paper, the more recent methods for the removal of dyes from water and wastewater have been discussed, and the performance and special features of each technique are also presented, as well as the advantages and limitations of each method.
Abstract: Dyes are an important class of organic pollutants and are well known for their hazardous effects on aquatic life in general and human beings in particular. In order to reduce the negative effects of dye contaminated wastewater on humans and the environment, the wastewater must be treated carefully before discharge into main streams. Advances in science and technology have led to the evolution of several techniques for the removal of dyes from industrial and domestic effluents. In this review, the more recent methods for the removal of dyes from water and wastewater have been discussed. Wastewater treatment techniques such as adsorption, oxidation, flocculation–coagulation, membrane filtration and biological treatment have been highlighted. In addition, efforts were made to review all the available techniques and recently published studies from 2010–2014. Furthermore, the performance and special features of these technologies have been summarised. Advantages and limitations of each technique are also presented. A thorough literature survey revealed that chemical oxidation, adsorption, and biological treatments have been the most frequently investigated techniques for dye removal over the past few years.
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TL;DR: 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 is offered.
537 citations
Cites background from "Recent Applications of Electrocoagu..."
...The literature indicates that the history of EC extends to the past hundred years, where it has been employed to treat water containing pollutants such as: heavy metals, tannery, textile and colored wastewater, pulp and paper industry wastewater, oily wastewater and food industry (Kuokkanen et al., 2013; Moreno et al., 2009)....
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...…the history of EC extends to the past hundred years, where it has been employed to treat water containing pollutants such as: heavy metals, tannery, textile and colored wastewater, pulp and paper industry wastewater, oily wastewater and food industry (Kuokkanen et al., 2013; Moreno et al., 2009)....
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TL;DR: The electrocoagulation (EC) process is an electrochemical means of introducing coagulants and removing suspended solids, colloidal material, and metals, as well as other dissolved solids from water and wastewaters as discussed by the authors.
429 citations
TL;DR: In this paper, the authors reviewed the factors that affect heavy metal adsorption onto industrial effluents using industrial solid waste (ISW), such as contact time, temperature, pH, and adsorbent dose.
Abstract: Industrial solid waste (ISW) is the waste obtained from the industrials activities which include any solid materials that are rendered useless during a manufacturing process. The ISW considers a global environmental problem and serious solutions must be taken to face this problem and decrease its environmental load and impact. Adsorption of heavy metal from industrial effluents using ISW is considered as a promising, potential and inexpensive alternative concept for ISW management. The ISW offering potential advantages as the zero cost, availability, high efficiency, and green alternative source. Heavy metals adsorption onto ISW is a complex process that affected by several factors including initial metal ions concentration, contact time, pH of the solution, temperature and adsorbent dose. In this paper, we review the factors that affect heavy metal adsorption onto ISW, such as contact time, temperature, pH, and adsorbent dose. The chief findings of the present review are: (1) The heavy metal ions removal% is high at the initial stage of the adsorption process then it decreases till it reaches equilibrium. (2) Temperature greatly affects the heavy metal adsorption process. (3) There is a definite pH value for each metal ion, at which the extreme adsorption of those metal ions occurs. (4) Increasing adsorbent dose generally increases catalytic activity due to the increase in the total surface area and the number of active places on the surface of the adsorbent. Knowing the factors that affect heavy metal adsorption onto ISW will help in optimizing the condition for heavy metal adsorption onto ISW.
169 citations
TL;DR: In this article, a Zn anode was applied for the first time to remove the organic load of a liquid effluent, and different operating conditions (pH, current density, distance between electrodes, nature of electrolyte and kind of cathode) were tested with synthetic phenolic wastewater, in order to optimize the process.
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References
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TL;DR: In this article, the development, design and applications of electrochemical technologies in water and wastewater treatment are reviewed with particular focus on electrodeposition, electrocoagulation, electroflotation (EF), and electrooxidation.
2,577 citations
"Recent Applications of Electrocoagu..." refers background or result in this paper
...[3,4] have addressed the subject recently, in addition to older reviews, (namely [1,2,5]), even though a significant number of studies on EC have Corresponding author....
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...This was mainly due to the then high electricity and investment costs [2]....
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...This phenomenon is thought to be attributed to pitting corrosion, especially in the presence of chlorine ions [2]....
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TL;DR: In this article, the effects of solution pH and temperature on the adsorption of fluoride onto bone char made from cattle bones were investigated, and it was found that the maximum adaption took place at pH 3.
Abstract: The effects of solution pH and temperature on the adsorption of fluoride onto bone char made from cattle bones were investigated in this work. It was found that the maximum adsorption took place at pH 3 and the adsorption capacity decreased nearly 20 times augmenting the pH from 3 to 12. This behavior was attributed to the electrostatic interactions between the surface of bone char and the fluoride ions in solution. The adsorption capacity was not influenced by temperature in the range from 15 to 35 °C. A comparison of fluoride adsorption capacities among several adsorbents revealed that the adsorption capacity of the bone char was 2.8 and 36 times greater than those of a commercial activated alumina (F-1) and a commercial activated carbon (F-400). The adsorption capacity is considerably dependent upon the physicochemical properties of the bone char surface and the solution pH.
1,865 citations
TL;DR: In this article, the results of the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst were reported.
Abstract: Biodiesel is produced by the transesterification of oil triglycerides with methanol or ethanol, in the presence of a homogeneous or heterogeneous catalyst. This study aims to report the results of the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst. The effect of the CaO nanoparticles concentration on the NaX zeolite surface was studied in the range of 5−25 wt %. The transesterification reaction was carried out at reflux temperature of methanol, atmospheric pressure, a reaction time of 6 h, and with a 6:1 molar ratio of methanol to sunflower oil. Catalyst characterization was carried out by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. It was concluded that methyl esters content is highly influenced by basicity and that the best catalyst was the one holding 16 wt % CaO nanoparticles. The produced biodiesel was 93.5% methyl esters and was found to fulfill the specifications of Europ...
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TL;DR: In this paper, a detailed understanding of the sweep flocculation mechanism is provided, especially with regard to the role of charge neutralization and hydroxide precipitation. But the results can be reasonably well explained in terms of established ideas, and there are also some uncertainties regarding the action of pre-hydrolysed coagulants.
1,424 citations
"Recent Applications of Electrocoagu..." refers background in this paper
...surfaces bring about electroflotation by adhering to agglomerates and carrying them to the water surface [21]....
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TL;DR: 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.
1,228 citations
"Recent Applications of Electrocoagu..." refers background or result in this paper
...[3,4] have addressed the subject recently, in addition to older reviews, (namely [1,2,5]), even though a significant number of studies on EC have Corresponding author....
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...75 5 5 - 9 [5] Dye: 40 - 200 (optimum 100) Color: 99 ~0....
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...The a C) include economic aspects (relatively low investment, maintenance, energy, and treatment costs), significantly lower volume of sludge produced, better sludge quality (lower water content, much larger and more stable flocs with better settlability), similar or slightly better efficiency, avoidance of chemical additions, ease of automation, simple equipment and compact size of EC systems (allowing decentralized treatment), greater functional pH range and pH neutralization effect, and the presence of electroflotation (EF) [5]....
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