Low energy/cost desalination: low dose and low mean ion resident time in concentrate stream of electro-dialysis reversal

A B S T R A C TElectrodialysis reversal (EDR) has been innovative based on unplanned indirect potable water reuse to replace the same amount of raw water withdrawn from brackish (sea) water source and conserving 15-20% of freshwater by reusing tertiary-treated municipal wastewater (TTMWW) as feed in the concentrate and electrode stream while brackish groundwater (sea water) remains feed into dilute stream. By substituting TTMWW, our analysis shows the resulting total dissolved solid (TDS) concentration in the waste stream lower than that in the original source of brackish groundwater (sea water) which fed into dilute stream. The waste from EDR system with TTMWW as feed in concentrate and electrode streams can be recharged back into groundwater (sea water) source which do not add the TDS concentration. In fact, it reduces the TDS concentration by dilution. New significant findings are: (1) 17,500 m 3 /d of freshwater could be saved with the data from 1990; the saving would be increased in 2011 and much more in future due to the increasing installation of ED/EDR and (2) cost reductions by enhancing the life of membrane and electrodes; and by reducing current required to attract ions and antiscalant due to low concentration of TDS and low scale causing ions in the TTMWW which fed into concentrate stream.

Section: Cost Reductionmentioning

confidence: 97%

Section: Desalination and Water Treatmentmentioning

confidence: 99%

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

Myint

Ghassemi

Nirmalakhandan

2013

“…Because the costs of HCl and SHMP dosage in Dirab and Labakha-hawaita, Saudi Arabia are 15 and 83 times higher than power cost [32] in Table 10. The author [38] analyzed to operate equal dimensional EDR with the optimal R up to MIRT c < 130 min for eliminating chemical usage to lower the cost; the optimal R, depends on species of Ca 2þ , Mg 2þ , HCO 3 À , and SO 4 2À ions concentrations and TDS in feedwater; polar reversal interval (PRI), can be determined from Monograph proposed by [38].…”

Section: Literature Review In Preventing Caso 4 Scaling With and Withmentioning

confidence: 99%

“…Fig. 2 [38]. In the classical EDR, the dimensions, flow, and velocity of dilute and concentrate are theoretically equal and practically approximately equivalent; LSI and CaSO 4 saturation are normally use as indicators to control the scaling and fouling processes in concentrate stream as such LSI < þ2.16 for preventing CaCO 3 from fouling and CaSO 4 saturation level < 200 for averting CaSO 4 from precipitation.…”

Section: Literature Review In Preventing Caso 4 Scaling With and Withmentioning

confidence: 99%

Design of ILEDR for brackish groundwater: A literature review approach

Myint¹,

Ghassemi²,

Nirmalakhandan³

2010

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...

“…Improvements in EDR include improvements in the areas of design, operation, and brine reuse in bio-energy production [12]. Further and recent improvement in operating EDR with higher recovery rate is achieved without any anti-scalant and without requirements of acid addition [13]. That new EDR operated with Langelier saturation index at 2.29 and CaSO 4 saturation level 358.9% at lower dose and lower mean ion resident time.…”

Section: Introductionmentioning

confidence: 99%

Remediation of brackish groundwater in United Arab Emirates using electrodialysis technique

Eid

Elshorbagy

2013

A B S T R A C TMany Gulf countries including United Arab Emirates "UAE" suffer from major shortage of drinking water produced from natural resources. In these countries, it is essential to make use of water from underground reservoirs of different qualities. In Al Ain and, till recently, major percentage of drinking water resources had been produced from groundwater aquifers. Intensive discharge of groundwater resources in several aquifers given the limited replenishing inflows and the major percolations associated with farming activities overlying these aquifers have resulted in increasing their salt content and invalidate their usage for drinking purposes. Desalination of brackish water is a major potential way of producing low-cost drinking water. Electrodialysis, a technique based on the transport of ions through selective membranes under the influence of an electrical field, has proved its feasibility and high performance in the desalination of brackish water. In this research, the design and optimization of an electrodialysis cell for brackish water desalination of major aquifers of Al Ain City, UAE, is studied. Different laboratory experiments are conducted to analyze the sensitivities of different design parameters on the configured cell, evaluate different operational schemes of the configured cell, and select the one achieving the highest desired efficiency.