Application of RO System to Desalinate Brackish Surface Water in Southern Iraq

Abstract

Brackish surface water desalination is a primary path to relieve the shortage of useable water. The application of reverse osmosis (RO) membrane technology to desalinate the surface water in southern Iraq has recently increased due to the fresh water scarcity for drinking water to meet local needs in this region. Several studies by using simulated brackish surface water which represented the same quality of the water of this region have been conducted. In this study, actual samples of brackish surface water from three locations (Al-Jeweber, Al-Hadam and Al-Masheb) which are, respectively, located in the southern provinces of Iraq (Thi-Qar, Maysan and Basrah) were used as a feed water to conduct several desalination experiments. These feed waters were used to run a pilot scale of spiral wound reverse osmosis (RO) membrane system. The purpose of this research is to study main parameters of RO membrane system as a result of the application of this technology to desalinate the brackish surface water of the Iraqi marshes. The changes of the flow and quality of the permeate and concentrate of the RO membrane system with time were investigated. In addition, salt rejection by the RO membrane including total dissolved solid (TDS), electrical conductivity (Ec), total hardness (TH), sodium (Na), potassium (K), carbonate (CO₃), bicarbonate (HCO₃), alkalinity (Alk.), chloride (Cl^-), total organic carbon (TOC), nitrite (NO₂)_, nitrate (NO₃), phosphate (PO₄), sulfate (SO₄), iron (Fe)  and zinc (Zn) were also studied . Moreover, the effect of the pretreatment on the water quality that is used as feed water for the RO system was included in this study. The results showed that 95.9% to 98% of total dissolved solids (TDS) removal percentage was attained for all runs conducted for the three selected sites. In addition, a wide range of permeate water flux which was (0.3442 – 1.3042) Lpm/m² was achieved. Moreover, pretreatment unit results showed that 90.67%, 93.9%, and 97.32% of turbidity reduction and 50.8%, 60%, and 71.7% of total organic carbon (TOC) reduction of the feed water of the three selected locations were achieved.

Keywords: Brackish water, Desalination, RO membrane, Salt rejection.