Applied Chemical Engineering (2021) Volume 4 Issue 1 doi: 10.24294/ace.v4i1.479 1 Original Research Article Optimization of electrodialysis unit for partial desalination: Batch and continuous operation H. M. Abdel-Ghafar 1* , E. A. Abdel-Aal 1 , D. El-Sayed 1 , J. Hoinkis 2 1 Central Metallurgical Research and Development Institute (CMRDI), Cairo, Egypt. E-mail: hamdy.maamoun@ya- hoo.com 2 Karlsruhe University of Applied Sciences (HSKA), Germany ABSTRACT In recently few years, application of membrane technologies in sea water desalination is increased compared to other desalination technologies. Electrodialysis membrane technology is still limited in seawater desalination due to the high operation cost and its limitations for high salty water. Electrodialysis desalination cost is proportional to the amount of salt, which must be carried out through the membrane. Seawater desalination with high salt content of NaCl (42 g/L) was applied using IonTech electrodialysis unit. Partial desalination process was studied in two separate experiments, batch and continuous operation. Operation parameters like voltage applied, electrolyte concentration and time of desalination were studied under batch mode process. Continuous operation process was carried out to confirm the partial desalination process of electrodialysis. The limited current density is determined, 1.49 A/m 2 and 1.15 A/m 2 for theoretical and exper- imental, respectively. The specific energy consumption was calculated, 7.15 kWh/m 3 . Keywords: Electrodialysis; Partial Desalination; Potential Difference; Energy Consumption ARTICLE INFO Received: 10 February 2021 Accepted: 30 March 2021 Available online: 7 April 2021 COPYRIGHT Copyright © 2021 H. M. Abdel-Ghafar et al. EnPress Publisher LLC. This work is li- censed under the Creative Commons Attrib- ution-NonCommercial 4.0 International Li- cense (CC BY-NC 4.0). https://creativecommons.org/licenses/by- nc/4.0/ 1. Introduction Scarcity of utilizable fresh water is obstacle for most countries around the world. Therefore, some special processes are needed to de- salinate salty water of the oceans and seas [1] . Suitable desalinating meth- ods for water treatment of seawater can be effective to overcome the fresh water scarcity. Electrodialysis (ED) is one of these methods which have been used for many years. The basic principles of ED have been reviewed in the literature [2] . Seawater desalination using electrodialysis was studied by Sadrza- deh and Mohammadi [3] . To evaluate effects of operation parameters, a L9 orthogonal array (four factors in three levels) was employed. Tem- perature, voltage applied, flow rate and feed concentration effects on separation percentage of ions have been studied. Maximum percentage of salts removal was obtained at the highest voltage applied (9 V), lowest feed concentration (10 g/L), high temperature level (55 o C) and lowest flow rate level (0.07 mL/s). It was found that, feed concentration is the most influential factor on ED performance (its contribution percentage was calculated to be 82.4%) [3] . The desalination efficiency of an electrodialysis unit is dependent on variable and fixed parameters. These variable and fixed parameters are like applied voltage, feed and permeate concentration, type and con- centration of electrolyte, flow rate, ED stack construction, current den- sity, membrane permselectivity and recovery rates [4] . For highly efficient