In isolated remote area or islands, drinkable water is precious due to lack of drinking water treatment facilities and energy supplies. Thus, a robust and reliable water treatment system with natural energies is needed to reuse the wastewater or to desalinate groundwater/seawater. In this work, an ED-FO hybrid membrane system driven by renewable energy (solar energy), named EDFORD (ED-FO Renewable energy Desalination), is proposed to produce high quality water (potable) from secondary wastewater effluent or brackish water.
In this hybrid membrane system, feed water (secondary wastewater effluent or brackish water) was drawn to the FO draw solution while the organic and inorganic substances (ions, compounds, colloids and particles) were rejected. Then the “diluted” draw solution was pumped to the solar energy driven ED as the diluate and the concentrate. In the ED unit, the diluate was desalted and the high quality water was produced; while the concentrate was concentrated and was circulated to the FO unit and acted as the draw solution again.
Results show that the water produced from this system contains low concentration of TOC, carbonate and cations from feed water and low conductivity, thus, is potable. The water production price in view of the membrane and the panel material is 3.32 to 4.92 EUR.m-3 (300 days per year) for this small size potable water production system.