Inorganic trace contaminant removal from real brackish groundwater using electrodialysis

Abstract

Abstract The removal of inorganic trace contaminants from a real brackish groundwater from a remote Australian community using electrodialysis was investigated. Systematic investigation of applied voltage and solution pH was aimed to elucidate removal and deposition mechanisms in a complex water. A higher applied voltage enhanced removal of arsenic (V), boron, lithium, selenium (VI) and uranium. The removal of boron, lithium, sulfate, uranium, calcium, magnesium, strontium, zinc and selenium was pH dependent while the removal of bromide, chloride, fluoride and nitrate was pH independent. The precipitation of insoluble species at high pH and their complexation with other contaminants resulted in membrane deposition in the form of scaling. This influenced system performance in regards to an increase in stack resistance and decrease in removal of total dissolved solids. The hydrated radius and strength of hydration shells played a less important role in the transport and removal of ions during electrodialysis of real water in comparison to other parameter such us ion concentration and solution pH. Results from this study showed that although electrodialysis is effective in the removal of contaminants from real waters, consideration needs to be given to its long-term practical applicability in regards to membrane scaling.