Optimization of osmotic pressure usage for safe water production in the context of combining water reuse and desalination

This thesis demonstrated, through systematic modelling and design approaches, that by optimizing osmotic dilution benefits, achieving WW recovery as high as 90% in FO while enabling RO desalination energy below 1 kWh/m³, which is substantially lower than the typical energy demand for treating full strength SW. Processing diluted SW in an existing desalination plant showed feasibility to retrofit to FO-RO hybrid and also enhance permeate production as high as 67% with existing plant design. However, comparing FO-RO hybrid with independent schemes energetically, standalone water reuse remained attractive. Beyond this, the work showed that integrating FO as a concentration step hinges on understanding how hydraulic conditions, flow orientation, module arrangement, and intrinsic FO mass‑transfer limitations collectively shape the achievable recovery and proximity to osmotic equilibrium. Insights from combined pilot‑scale experiments and modelling revealed that a tree‑shaped, multi‑module configuration operated in counter‑current flow (tested using a two‑stage FO system with three modules) promotes more balanced hydraulic distribution and maintains the osmotic driving force more effectively than a simple series layout