Design of ILEDR for brackish groundwater: A literature review approach

Abstract

A literature review was done in details in desalination by using electrodialysis reversal (EDR). All available data -source of water entered into pretreatment and/or directly into EDR, physicochemical characteristics of water, targeted pollutants, methods and the reasons for the pretreatments, specifications used of EDRs, developments/improvements in EDR, fouling causing compounds and methods to control fouling, membrane types, membrane assembly, spacer, and concentrate management, method, and recovering of ions were searched and summarized in Tables 1-3. From the tables, the concentrations profiles of the targeted pollutants were observed in different sub-processes (i.e., pretreatment, ERD dilute and concentrate streams). The percentage removals of individual ion from different literatures were compared. The concentrations of fouling causing compounds (for examples, CaSO 4 and MgSO 4 ) in concentrated streams were eliminated by individual separation process with the specific different types of permselective membranes in four different stages. All these summarized data were used as tools, references, and comparisons to design and select the sub-processes in ILEDR project to treat the brackish groundwater into the drinking water. Design includes designs I (using a single type of membrane pair) and II (using four different types of mono-and di-valent permselective membrane). Permselective membrane design shows 7% cost saving while comparing to the single type of membrane design with the same water recovery rate, the same demineralization rate, and the same membrane life. The saving increases up to 15-18% if membrane life is considered in the design.self-cleaning by reversal the chemical reactions, electricity driving force, and the flows. The effectiveness of current-reversal process of EDR are shattering and detaching polarization films four times/hour to prevent polarization scale; contravention up freshly precipitated scale or seeds of scale and flushing them back into waste stream before they can cause scratch to membrane; reducing slime formations on membrane surface; reducing problems associated with the use of chemicals; cleaning electrodes with acid automatically during alternative anodic operation [4] in reversal. There is a period (1-2 min [4]) instantaneously following the polarity reversal, the waters from both dilute and concentrate are required to send back to the feed stream or diverted to waste because these waters are ''off specification''.EDR efficiency depends on method to prevent membrane from fouling; ion's charge and mobility, solution conductivity, relative concentrations, applied voltage, and the characteristics of the ion-exchange membranes, especially its permselectivity [5]; system design [6,1]; materials used in membrane [7].EDR is not cost effective at plant capacity lower the 40 m 3 /h while comparing with R.O; Elyanow and Persechino recommended that high recovery (94%), elevated SDI (6-12), potential for biofouling, hard-totreat, high hardness, lower salinity waters (from 200 to 5,000...

Design and optimization of electrodialysis process parameters for brackish water treatment

“…The other coating material like ruthenium was also used by researcher [25] with and without iridium and titanium in composition with coating material to test the life expectancy of electrode. Ruthenium coating containing iridium and more titanium shows the more service life and performance for EDR process [25], [26]. Carbon electrode is also built and tested at lab-scale by Winter [23] but not fulfilling the basic requirement, the electrodes were having brittle and corrosive in nature.…”

Complete sustainability in electrodialysis reversal desalination: reusing tertiary-treated municipal wastewater as feed in the concentrate stream and electrodes rinsing water

“…Both of these technologies, however, waste about 15-35% (15-20% in ED/EDR [13] and 25-35% in RO) of feed water as brine (RO) or concentrate (EDR) depending on water recovery rate; TDS removed (volume of product water produced) rate over the effective membrane area and current (voltage) applied [14]; equipment and membrane life; chemical dosing; allowable annual capital and operation cost; water chemistry of feed water [15]; and demineralization degree. Waste disposal costs could range from 5 to 33% of desalination cost [16,17]; in the case of inland sites, estimates show that it can be in the order of 15% of the cost of desalination [18].…”