Abstract: There is provided a process for treating an aqueous solution including impurity material disposed in a first state, comprising:, comprising: modifying the state of the impurity material, disposed in its first state, with effect that a second state of the impurity material is obtained, such that a conditioned aqueous solution, including the modified impurity material, is obtained. The conditioned aqueous solution is contacted with an operative sorptive media with effect that at least a portion of the modified impurity material becomes sorbed to the operative sorptive media, such that an impurity material-depleted aqueous solution is produced.

Abstract: The filter contaminant loading capacity of a depth granular. media filter is increased by imposing a so-called “back-slip” on the filter bed. At intervals between normal backwashing, a volume of liquid is passed upwardly through the media bed under flow conditions selected to displace at least some of the contaminants upwardly in the bed while essentially removing none of the contaminants from the filter vessel. Preferably, the filter bed comprises at least two media types of different but uniform particle sizes and densities, the media types each forming a distinct layer in which the effective particle size of the media in each successive layer decreases in a downward direction in the vessel.

Abstract: A process using an amphoteric ion-exchange resin, also known as a "snake-cage polyelectrolyte" resin separates kraft white liquor into sulphide-rich and caustic-rich components. The sulphide-rich component can be used in the initial stage of pulping, pretreatment of wood chips prior to pulping, or it can be used to make polysulphide-rich liquor. The caustic-rich component can be used in the final delignification phase, in place of sodium hydroxide or white liquor in oxygen delignification, pH adjustment and flue gas scrubbing. The same system can be used to separate green and polysulphide liquors into sulphide-rich and sulphide-poor components, and to remove sulphide from other mill caustic streams contaminated with sulphide.

Abstract: A process employing a fixed-resin bed Acid Retardation Unit (ARU) to separate spent acid from chlorine dioxide generators into a de-acidified sodium sulfate component and a purified sulfuric acid component. The de-acidified sodium sulfate produced is returned to the chemical recovery cycle of the kraft mill in place of acidic chlorine dioxide generator effluent thereby avoiding the destruction of alkalinity in pulp mill liquors. In addition, sulfuric acid is purified providing an opportunity for reuse in various mill applications, and/or concentrated and recycled to the generator. Alternatively, to avoid high evaporation costs, the purified acid can be used to regenerate a cation-exchange unit (CEU) used in the conversion of sodium chlorate to a sodium chlorate/chloric acid mixture which is fed to the generator in place of sodium chlorate and sulfuric acid. Using this approach, the sulfuric acid requirement of chlorine dioxide generators and, in turn, the amount of acidic generator effluent can be reduced.