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Membrane Technologies for Water Purification
Published in P.K. Tewari, Advanced Water Technologies, 2020
The ED system consists of cation and anion membranes, which are placed in an electric field. The cation-selective membrane permits only the cations and anion-selective membrane permits only the anions. The transport of ions across the membranes results in ion depletion and ion concentration in alternate cells. Electrodialysis is used widely for production of potable water from brackish water, production of ultrapure water, etc.
Organics, Salts, Metals, and Nutrient Removal
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
R. David Holbrook, Sun-Nan Hong, Derk T.A. Huibers, Francis X. McGarvey, Chakra J. Santhanam
Electrodialysis system performance is influenced by the relationship between the solution concentration and membrane stack resistance and between the current density and solution velocity. Pretreatment including deaeration, filtration, and other operations is often required, depending on the feed characteristics.
Chemical Treatment Processes
Published in Ralph L. Stephenson, James B. Blackburn, The Industrial Wastewater Systems Handbook, 2018
Ralph L. Stephenson, James B. Blackburn
Electrodialysis is a concentration process, used primarily for heavy metals in wastewater treatment, wherein a large volume of water with heavy metals is concentrated to a small volume of water with the same mass of heavy metals. Electrodialysis utilizes a direct electric current to disassociate ions and drive them across a membrane. Electrodialysis membranes are stacked between electrodes. There are cation and anion membranes, and these are alternated so water comes in between the membranes, the ions disassociate and cross the membranes. A salt stream is discharged from one side of the membranes and a desalted stream from the other side. Electrodialysis will only work for salts that can ionize, and is ineffective for non-ionizing compounds, such as organics. It is commonly used in water treatment to reduce total dissolved solids or salt concentrations in water. The theoretical amount of current required to accomplish salt removal is: I = FF1ΔNeCp
Resource recovery and utilization of bittern wastewater from salt production: a review of recovery technologies and their potential applications
Published in Environmental Technology Reviews, 2021
Arseto Yekti Bagastyo, Afrah Zhafirah Sinatria, Anita Dwi Anggrainy, Komala Affiyanti Affandi, Sucahyaning Wahyu Trihasti Kartika, Ervin Nurhayati
Membrane electrodialysis is a separation method that involves the application of ionic semipermeable membranes in the presence of an electric current as of the driving force. The rejection of ions is affected by the concentration, effective membrane area, operating time, current density, and voltage. Electrodialysis is commonly used for the recovery of ionic materials from industrial wastewater, desalination, and fractionation processes, and is currently being developed for bittern wastewater [83–85]. Minerals that have been successfully recovered include Mg2+ [23] and Li+ [22,63,83,86]. For example, Ye et al. [23] recovered magnesium from seawater using standard anion and cation exchange membranes, a monovalent selective cation exchange membrane, and an end cation-exchange membrane supplied by Polymerchemie Altmeier GmbH, Germany. The optimum rate of Mg recovery was 74.48–80.48%, which was achieved at 13 V with a Ca/Mg mass ratio of 4:3. The estimated energy consumption was in the range 8.38–11.69 kWh kg –1.
Application of algae as low cost and effective bio-adsorbent for removal of heavy metals from wastewater: a review study
Published in Environmental Technology Reviews, 2020
Abolhasan Ameri, Sajad Tamjidi, Faeghe Dehghankhalili, Arezoo Farhadi, Mohammad Amin Saati
Electrodialysis (ED) is an electro-membrane method, in which anions are applied to the membrane using electricity [77]. The aqueous solution is located between the anion and cation-exchange membranes. The anions and cations are only allowed to pass through the electrode and are maintained on the ion-exchange membrane [78,79]. The aqueous solution is divided into two parts, namely concentrate and diluent. The advantages of electrodialysis are the low use of chemicals and high water recovery [80]. The major drawback of the electrodialysis process is membrane scaling and fouling, so its use is limited in wastewater treatment [79]. The most important advantage of using this process is that it can be used to restore ion exchange resins or to use plating [80]. Figure 5 shows the electrolysis process [81].
Separation of metals from electroplating wastewater using electrodialysis
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Kyung Jin Min, Su Young Choi, Deokjin Jang, Jongkeun Lee, Ki Young Park
Electrodialysis is a technique used for simultaneously conducting ion exchange, purification, and concentration of an electrolyte in aqueous solution by passing ions through an ion exchange membrane under an electric field. In general, ion separation efficiency in electrodialysis varies depending on the inherent characteristics of the ion exchange membrane, operating conditions, and physicochemical properties of the metal ions (Cararescu, Purcar, and Vaireany 2012). In addition, selective ion separation using an ion exchange membrane is influenced by the inherent selectivity of the membrane, ion selective dependence, and concentration of metals in the influent. The ion separation efficiency is also determined by hydraulic properties such as apparent surface velocity, electrical characteristics due to the potential difference, and a constituent ratio of the ions according to the influent properties (Murthy and Chaudhari 2008). Therefore, to achieve the required quality of treated wastewater using electrodialysis, appropriate operating factors should be determined.