Removal of perchlorate from groundwater by the polyelectolyte-enhanced ultrafiltration process

Abstract

The polyelectrolyte enhanced ultrafiltration (PEUF) process for perchlorate removal from groundwater containing common co-contaminants like nitrate and sulfate was investigated. Existing processes such as ion exchange can remove perchlorate but with greater complexity, especially when applied in the presence of high nitrate and sulfate concentration. The effect of cationic polyelectrolyte, poly(diallyldimethyl ammonium chloride) (PDADMAC) concentration and the effect of nitrate and sulfate in a broader concentration range were observed. In the absence of other anions, a lower amount of PDADMAC (0.5-1 mM) can remove more than 90% of perchlorate from the aqueous phase. However, in the presence of 5 mM nitrate, perchlorate removal decreases as the available binding sites of PDADMAC for perchlorate are reduced. In the presence of both 1 mM to 10 mM nitrate and sulfate, 60-80% perchlorate was removed with 30 mM PDADMAC. The removal of sulfate and nitrate in this case was nearly 75% and 65%, respectively. The effect of other parameters such as relative flux, membrane material and pore size were also observed to study the feasibility of PEUF for perchlorate removal. Consequently, PEUF proved to be an effective perchlorate removal process owing to the high removal efficiency and suitability in groundwater remediation containing other contaminants.