Efficiency of Low-Pressure Reverses Osmosis (RO) in Desalination and TOC Removal from Caspian Seawater and Tajan River

Abstract

Water scarcity is a critical issue in Caspian Sea regions of Iran. Thus, people may use polluted water or saline brackish groundwater, estuarine water or seawater. This paper deals with the application of Low-Pressure reverse osmosis (RO) for removing salt and Total Organic Carbon (TOC) in synthetic and Caspian Sea waters. The study aims to achieve optimization at different pressures (30, 50, 70, and 90 PSI) with synthetic seawater at initial salt concentrations (5, 25, and 35 g/L TDS) at various retention time intervals (15, 30, 60, 90, and 120 minutes). The results showed that the low-pressure RO system was able to reject 95 %, 57 %, and 46 % of 5, 25, and 35 g/L of TDS from synthetic seawater. In addition, rejection efficiency was achieved at 86 % and 78 % for Caspian seawater and Tajan River, respectively. In addition, optimal conditions (pressure: 70 PSI, time: 120 min) for salt rejection included 16-23 %, 93-94, 52-56 %, 88-90, and 22 % for 35g/L TDS, Tajan River, 5g/L TDS, 25g/L TDS, and Caspian seawater, respectively. Moreover, TOC rejection was achieved at >95 % and >97 % of Tajan River and Caspian seawater, respectively, at an overall 120-minute interval. In the case of growing environmental pollution that is discharged into Caspian sea including industrial and agricultural effluents from rivers, this study proposed the suggested pilot as a simple design that will significantly reduce salt, TOC, and TDS.