Treatment of industrial wastewater for reuse

Faced with environmental and water shortage problems at their Tutuka Power Station, Eskom, the South African Power Company approached Envig to assist them in finding a solution. This was achieved by the installation of a spiral reverse osmosis (SRO) plant to treat 12 Mld of mine water and spent cooling water. The result is a mine with no effluent problems, a new source of water for the power station and a treatment plant which produces significantly better cooling tower water and zero liquid discharge. Process details and 6 months of operational data are presented which demonstrate that good pretreatment and cleaning system design allow SRO to produce consistent high-quality water from this difficult and varying feed.

The dual difficulties of mine water discharge and poor cooling water treatment plant operation were successfully overcome by the installation of a SRO plant. The effectiveness of the plant can be attributed to the careful design and operation of the systems pretreatment and cleaning systems which mitigate the effect of the high organic and biological fouling capacity of the feed water. Effective use has been made of all liquid streams providing both mine and cooling water with “zero liquid discharge” status. The effectiveness of fouling resistant SRO membranes has been demonstrated on a largescale industrial application. This now allows organic and inorganic effluents to be considered for process water reuse duties using SRO.