Techno-Economic Evaluation of 1200 m³/Day Seawater Desalination Plants: Comparative Analysis of RO, MSF, and MED Technologies

Abstract

Libya, like many arid countries, relies heavily on groundwater resources, which are increasingly scarce. With a 1950 km Mediterranean coastline offering an abundant but highly saline water source (35,000–38,000 ppm), seawater desalination is essential to meet national water demands. This study presents a techno-economic evaluation of three desalination technologies—Reverse Osmosis (RO), Multi-Stage Flash (MSF), and Multi-Effect Distillation (MED)—for a 1200 m³/day plant. RO design was conducted using ROSA software, while MSF and MED were modeled thermodynamically.RO requires significantly lower seawater intake (117 m³/h) compared to MSF (475.7 m³/h) and MED (200 m³/h), with corresponding plant efficiencies of 43%, 10.5%, and 25%. RO produces potable water (190 ppm TDS), while MSF and MED yield ultra-pure water (~50 ppm TDS), necessitating remineralization. RO operates without steam input, unlike MSF and MED (7.3 m³/h steam), and demands 235 kW of electrical power versus 245 kW (plus steam) for MSF and 50 kW (plus 7.5 m³/h steam) for MED. RO’s high brine pressure (53.5 bar) enables energy recovery, whereas MSF and MED discharge warm brine at low pressure, posing environmental challenges. Economically, unit water costs are $0.37/m³ for RO, $1.52/m³ for MSF, and $1.21/m³ for MED. Overall, RO is the most technically and economically viable option for this capacity under Libyan conditions.