Investigation into alternative water treatment technologies for the treatment of underground mine water discharged by Grootvlei Proprietary Mines Ltd into the Blesbokspruit in South Africa

An optimization strategy for the design and operation of a small-scale solar-powered reverse osmosis desalination system is presented. It has been analyzed and optimized with regard to power needs and energy consumption. Both quantities scale linearly with the concentration of the total dissolved salt (TDS) concentration in the feed solution. The desalination of brackish water at a TDS value of 3000 mg/L requires energy of approximately 0.84 kWh/m3. For seawater at a TDS value of 35,000 mg/L, this value increases to 7.0 kWh/m3. The selected type of membrane, the membrane configuration, the recovery rate, the area of membrane and the efficiency of the high pressure unit crucially affect energy consumption. The minimum desalination cost has been estimated for a small-scale system. It approximately scales linearly with the TDS value from US$3.3/m3 for TDS of 3000 mg/L to US$7.8/m3 for seawater. Preliminary experimental results are presented and compared with the model calculations.