Electrochemical Water Treatment Methods
01 Jan 2017-pp 47-130
TL;DR: The most common electrochemical water treatment methods are electrochemical oxidation used for mineralization of organic pollutants, water disinfection, removal of cyanides, and sulfides; electrochemical reduction used for metals recovery and transformation of persistent organic compounds to less toxic forms; electrocoagulation and electroflotation used for suspended particles removal; and electrodialysis used for water desalination as discussed by the authors.
Abstract: Electrochemical methods can be applied for the treatment of municipal and industrial waters and wastewaters. The only prerequisite for the use of electrochemical methods is to preliminarily remove large particles and other physical inclusion from water, which is usually made in conventional treatment as well. When this condition is satisfied, electrochemical methods can remove any kind of pollutants, including organic and inorganic compounds, microorganisms, and ions, allowing to obtain clean water of distilled water quality. The most common electrochemical water treatment methods are electrochemical oxidation used for mineralization of organic pollutants, water disinfection, removal of cyanides, and sulfides; electrochemical reduction used for metals recovery and transformation of persistent organic compounds to less toxic forms; electrocoagulation and electroflotation used for suspended particles removal; and electrodialysis used for water desalination. Theoretical background of these methods as well as the main area of their application will be considered in this chapter.
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08 Jul 2021
TL;DR: In this paper, the authors comprehensively and critically review and discuss these methods in terms of used agents/adsorbents, removal efficiency, operating conditions, and the pros and cons of each method.
Abstract: Removal of heavy metal ions from wastewater is of prime importance for a clean environment and human health. Different reported methods were devoted to heavy metal ions removal from various wastewater sources. These methods could be classified into adsorption-, membrane-, chemical-, electric-, and photocatalytic-based treatments. This paper comprehensively and critically reviews and discusses these methods in terms of used agents/adsorbents, removal efficiency, operating conditions, and the pros and cons of each method. Besides, the key findings of the previous studies reported in the literature are summarized. Generally, it is noticed that most of the recent studies have focused on adsorption techniques. The major obstacles of the adsorption methods are the ability to remove different ion types concurrently, high retention time, and cycling stability of adsorbents. Even though the chemical and membrane methods are practical, the large-volume sludge formation and post-treatment requirements are vital issues that need to be solved for chemical techniques. Fouling and scaling inhibition could lead to further improvement in membrane separation. However, pre-treatment and periodic cleaning of membranes incur additional costs. Electrical-based methods were also reported to be efficient; however, industrial-scale separation is needed in addition to tackling the issue of large-volume sludge formation. Electric- and photocatalytic-based methods are still less mature. More attention should be drawn to using real wastewaters rather than synthetic ones when investigating heavy metals removal. Future research studies should focus on eco-friendly, cost-effective, and sustainable materials and methods.
279 citations
TL;DR: One of the most effective approaches towards reducing energy consumption and membrane fouling rate is the integration of MBR with low-voltage electrochemical processes in an electrically-enhanced membrane bioreactor (eMBR), while research on eMBR modeling and sludge reuse is limited.
104 citations
Journal Article•
TL;DR: The Pd-Cu/γAl 2 O 3 catalysts were prepared by impregnation method and introduced into the cathode chamber of a divided electrochemical denitrification cell with two graphite plates as the cathodes and anode, to enhance the nitrate removal efficiency and N 2 selectivity.
Abstract: Abstract The Pd–Cu/γAl 2 O 3 catalysts were prepared by impregnation method and introduced into the cathode chamber of a divided electrochemical denitrification cell with two graphite plates as the cathode and anode, to enhance the nitrate removal efficiency and N 2 selectivity. The Pd–Cu/γAl 2 O 3 catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), specific surface area measurements (BET) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). In the rationally designed electrochemical-catalytic (ECC) system, the as-prepared catalyst could significantly enhance the nitrate degradation rate to 1.08 mg/L at current density of 10 mA/cm 2 , which was approx. 2.5 times compared with the electrochemical (EC) system without catalysts adding in. Additionally, a higher nitrogen selectivity of 80.37% was obtained under the same experiment condition. The improved performances were likely due to the presence of a catalytic reduction reaction of nitrate with the appropriate amount of hydrogen generated by electrolysis as reductant. Significantly, the current efficiency was calculated and enhanced value of 20–40% (depended on current density) was obtained in the ECC process with a catalyst content of 1.0 g/L.
78 citations
TL;DR: An overview of electrochemical processes for water, process water, and wastewater treatment can be found in this paper, where some essential basics of these processes for the treatment of water are presented and examples for applications are given.
Abstract: Regarding the treatment of (waste)water, electrochemical processes have various advantages over other methods. They are robust, easy to operate and flexible in case of fluctuating wastewater streams. In addition, a relatively broad spectrum of organic and inorganic impurities can be removed. This contribution provides an overview of electrochemical reactors for water, process water, and wastewater treatment, which are already in technical‐scale operation or subject of research. Some essential basics of electrochemical processes for the treatment of water are presented and examples for applications are given. This is followed by a description of the reactors.
76 citations
TL;DR: In this article, the treatment of pharmaceutical industry wastewater by combination of electrocoagulation (EC), electro-Fenton (EF) and photocatalytic oxidation (PcO) processes was investigated.
Abstract: The wastewaters produced in many different operations in the pharmaceutical industry are considered as an environmental problem because of their hazardous and potential for impacts on the aquatic ecosystem. In this study, the treatment of pharmaceutical industry wastewater by combination of electrocoagulation (EC), electro-Fenton (EF) and photocatalytic oxidation (PcO) processes was investigated. Initially, EF or EC processes were applied to degrade and decompose recalcitrant organic pollutants and PcO was then sequentially carried out to remove total organic carbon (TOC) and mineralise remaining compounds from wastewater. The performance of sequential implementation of EC + EF, EC + PcO and EF + PcO processes was investigated by using different current densities, catalysts, reaction times and process order. The most effective degradation was observed in the 1 h EF using 5 mA/cm2 pulsed current density and optimum Fe:H2O2 molar ratio as 1:10 and then 4 h PcO using 1.5 g/L TiO2 and 10 mM H2O2. Results of sequential treatment processes indicated 64.0 % Total Organic Carbon (TOC), 70.2 % Chemical Oxygen Demand (COD) and 97.8 % Biological Oxygen Demand (BOD5) reduction and the energy consumptions were also calculated as 1051.21 kW h/kg TOC at 1 h EF and 4 h PcO.
64 citations
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