Potable Water HERO Process at Yalgoo

Abstract

The High Efficiency Reverse Osmosis (HERO™) process has been applied for the first time to provide potable water. The facility is located at Yalgoo, a gold mining town in outback Western Australia. The facility is owned by Water Corporation. The plant was supplied, installed and commissioned by Osmoflo, who are operating and maintaining the plant in partnership with the Water Corporation. The selection of this technology was driven by both quality and quantity restraints of the feed bore water and also the need to dispose of the concentrate in an environmentally responsible manner. Reverse Osmosis (RO) membrane technology was selected to reduce total dissolved solids, arsenic and nitrate to drinking water levels. High levels of silica in the bore water would have limited the recovery of a conventional RO, resulting in large volumes of concentrate to be disposed of and a potentially unsustainable bore water abstraction rates. Silica solubility increases as pH increases, however for most divalent and higher cations the opposite is true. In this process divalent and higher cations are removed by ion exchange (water softening) allowing the RO to be operated at high pH. By this means the silica scaling restraint on recovery is removed allowing operation at higher (90 – 95%) recoveries. This minimizes volume of concentrate disposal and hence costs of evaporation basins, and reduces the required abstraction from the water table. The plant was commissioned in June 2007. This paper provides some background on this technology and initial operating results.