In this work, the performance of a Reverse Osmosis (RO) process using different types of reverse osmosis (RO) and nanofiltration (NF) membranes is evaluated for brackish water desalination for producing irrigation-grade water. The proposed desalination system is a single-stage system, where three types of RO and two NF membranes were examined. The different desalination systems were simulated using ROSA72 software. In order to validate the theoretical model, the results obtained from the simulation were compared to those obtained from the experiment conducted in this work. The El-Moghra aquifer of Egypt is considered the test bed due to a considerable amount of data being available for this aquifer. The El-Moghra aquifer has 79 wells, and the available water data, when checked against several quality parameters, show that none of the investigated wells are suitable for direct irrigation without treatment due to problems of salinity, the sodium adsorption ratio, and low water quality according to the irrigation water quality index values. The obtained results show that nanofiltration membranes exhibited superior energy efficiency compared to reverse osmosis membranes. However, what sets the nanofiltration membranes apart is their ability to elevate water quality in 89.9% of the total investigated wells to an acceptable level for agricultural purposes. This underscores the nanofiltration membranes as a highly effective alternative to reverse osmosis membranes, demonstrating the capability to produce water suitable for irrigation while concurrently reducing operational costs due to the lower energy consumption in nanofiltration-based systems.

Water scarcity poses major constraints to sustainable rural development, particularly in arid regions. In Egypt, limited freshwater resources are increasingly prioritized for domestic use, compelling proposed large-scale land reclamation projects to rely on brackish groundwater. However, marginal water quality restricts cultivation to salt-tolerant crops, undermining the long-term profitability of ongoing agribusiness activities. This study is the first to evaluate the techno-economic viability of integrating decentralized desalination systems into the Moghra development area. A systematic hydrochemical assessment of 73 wells, using the Irrigation Water Quality Index (IWQI), classified 49 as “Severe Restriction” and 24 as “High Restriction”, confirming widespread concerns about groundwater suitability. A two-stage reverse osmosis (RO) desalination system powered by photovoltaic (PV) energy was designed to achieve a 70% recovery rate. An optimization model identified blending ratios that maximize post-treatment water quality while minimizing the desalinated water volume. Results showed substantial improvements: the average sodium adsorption ratio (SAR) decreased by 66%, and IWQI increased from 34 to 77. Consequently, 68 wells were reclassified as “Low Restriction” and 5 as “Moderate Restriction”, enabling a shift from salt-tolerant olives to higher-value crops (e.g., wheat–maize rotation). A cost–benefit analysis assessed trade-offs between desalination costs and resulting economic returns. Under the abstraction limit, the proposed RO–PV blending strategy yielded a 35% higher net present value (NPV) and a 15.7% internal rate of return (IRR), demonstrating both technical and financial viability. These findings provide actionable insights for policymakers, stakeholders, and investors to enhance water productivity and agricultural sustainability in arid regions.