Groundwater desalination for agricultural purposes using reverse osmosis and nanofiltration technologies: Case study wadi El-natrun, Egypt

Abstract

The current study aims to assess the water quality in Wadi El-Natrun (Egypt) for agricultural purposes and to design an optimal desalination system that considers the water quality, the power consumption, and the total cost of the system. Water quality was evaluated based on four indices: electrical conductivity (EC), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and toxicity risk of three ions (sodium, boron, and chloride). The proposed desalination systems are single- and double-stage hybrid systems based on reverse osmosis (RO) and nanofiltration (NF) membranes. The performance of these systems was evaluated and compared in terms of the quality of permeated water for agricultural uses. The net present value (NPV) was also used as an economic criterion to determine the optimal system for agricultural purposes from an economic point of view. The results showed that most of the wells investigated are not suitable for direct irrigation before treatment due to problems of salinity, sodium adsorption, and chloride toxicity. Reverse osmosis membranes have proven to be superior to nanofiltration for producing high-quality water for agricultural purposes. However, single-stage systems with nanofiltration membranes are the most cost-effective option for most of the wells investigated in the study; they are the best for 30 out of 47 wells. It is also concluded that the use of nanofiltration desalination technology for irrigation purposes is a feasible solution that would encourage investors to expand reclamation projects in the Western desert in Egypt.