PERFORMANCE EVALUATION OF CLOSED CIRCUIT AND CONVENTIONAL REVERSE OSMOSIS SYSTEMS: BRINE PRODUCTION RATE, CHEMICALS AND ENERGY CONSUMPTION

Nowadays many countries around the world are facing the crisis of water scarcity. It is no exaggeration to say that water scarcity is one of the greatest challenges in this century. Unfortunately, following factors exacerbate this challenge: fast population growth, expanding inefficient agricultural and industrial activities, poor management of water resources, water pollution, and climate change. The major problem is creating better balance between clean water demand and supply, Gosling and Arnell (۲۰۱۷). Since more than ۹۷ percent of the Earth's water that that people can access is salty, water desalination is the most common technology to produce clean water from different water sources, Qasim et al. (۲۰۱۹). Reverse osmosis (RO), a membrane-based desalination method, is the dominant technology used to convert brackish and sea water into consumable fresh water. RO system uses a semi-permeable membrane to remove all colloidal and dissolved matters from pressurized feed water. It produces a concentrated brine and a permeate flow which consists of almost pure water. Although RO technology is well understood and cost-effective, but managing the produced high salinity brine is still a major problem. Disposal of these large amounts of salty wastes -typically ۲۵% and ۵۰% of feed for brackish and sea water respectively- is a serious environmental problem, Bond and Veerapaneni (۲۰۰۷). Currently, there are a few brine disposal options. All of these options are accompanied by economic and environmental problems (Table ۱), Sethi et al. (۲۰۰۹), Mohamed et al. (۲۰۰۵).