A method for chemical fractionation of chloride from complex effluents

A method was developed to fractionate chloride ions from complex effluents using an ion exchange column. The procedure utilizes a strongly basic anion exchange resin with hydroxide ions as the exchange ion. The chloride within the effluent is exchanged for hydroxide which is less toxic to Ceriodaphnia dubia. The addition of hydroxide to the solution requires a pH adjustment to a physiologically acceptable pH for Ceriodaphnia with an acid. The fractions are added to Ceriodaphnia and the ET ₅₀ (median lethal time) determined. The column was applied to two effluents with suspected chloride toxicity. The column successfully removed virtually all of the chloride from the effluents. A significant reduction in toxicity was found following the process for one of the effluents. In addition, a control that consisted of the original effluent at the ionic strength of the column fractions revealed that chloride was a causative toxicant in both of the effluents.