Process water recovery via forward osmosis: membrane and integrated process development

This work reports on efforts to develop an integrated continuous forward osmosis system for the recovery of water from wastewater streams, highlighting critical process parameters to minimize energy consumption. Forward osmosis experiments were performed using NaCl draw solutions of various concentrations and the intrinsic membrane parameters (water permeability, draw solution permeability, and structural parameter) were then determined via nonlinear regression using MATLAB. The experimental data was then used to validate a theoretical water flux model, which was subsequently applied to simulate the forward osmosis performance under different hydrodynamic conditions using both NaCl and TMA-CO2-H2O (TMA: trimethylamine) draw solutions. Analysis of the energy efficiency of the TMA-CO2 draw solution regeneration stage revealed that the draw solution flow rate has a significant impact on energy consumption. Also, increasing the feed flow rate was found to slightly enhance the water flux up to 2.5%, while having a negligible impact on the downstream regeneration process energy consumption.