Techno-economic evaluation of hybrid multi-effect and membrane desalination systems for improved water production

This study introduces a hybrid desalination system combining a four-stage parallel-feed Multi-effect Desalination with Thermal Vapor Compression (MED-TVC) and Direct Contact Membrane Distillation (DCMD). The system recycles hot brine rejected from each MED-TVC stage into DCMD units, improving efficiency and reducing brine discharge. Techno-economic and exergy analyses indicate significant performance gains; at a steam temperature of 90 °C, the proposed hybrid system achieved a specific energy consumption of 25 kWh/m³ (11.6 % lower), and a levelized cost of water (LCOW) of 1.28 $/m³ (8.5 % reduction) compared to standalone MED-TVC. Optimal DCMD membrane area decreases from 17 m² at 65 °C to 9.2 m² at 95 °C, beyond which LCOW rises. The TVC part accounts for about half of system irreversibility, while sensitivity analyses confirm that capital expenditure (52.8 %) and steam costs (77.6 % of operational costs) heavily influence LCOW, indicating potential savings from reduced steam pricing.