Recycling of polluted wastewater for agriculture purpose using electrodialysis: Perspective for large scale application

Water deficiency is a critical issue that faces many countries, particularly those located in arid and semiarid zones. In Egypt, drainage wastewater (DWW) is used as an alternative source of irrigation directly or after it is mixed with Nile River water. Unfortunately, DWW is not suitable for irrigation directly or after being mixed with other water sources. In the present work, DWW was treated to meet the agricultural use requirements via electrodialysis (ED) based on agricultural water validity parameters, including removed Na+, the sodium adsorbed ratio (SAR), and the Na+ ratio. Our results indicate that a steady ED system (there is no flow in ED cell) is more efficient for DWW treatment in both regular ED and ED cation separation systems. For the regular ED steady system, removed Na+ levels exceeded 99% after 100 min. The SAR levels were also reduced from a high value of 22 to an allowable limit of 0.34-0.4, and the Na+ ratio decreased from close to 86% to 14.6-16.6%. The best salt removal results were obtained at an electrical potential level of between 65 V and 80 V over an operation period of 40 min. When cations alone were separated from DWW without anions, the applied electrical potential was remarkably decreased. Na+ removal levels reached as high as 99.3% after 100 min, and the depletion of Na+ reached 5.1 ppm-5.6 ppm from initial concentrations of 800 ppm. The SAR decreased from 22 to as low as 0.30-.34, and the Na+ ratio decreased from 86% to 13-19.5%. Finally, perspective for further approaches and large-scale application in Egypt would be introduced, which may be suitable for North Africa, and Middle East countries. (C) 2017 Elsevier B.V. All rights reserved.