Long-term performance of biological ion exchange for the removal of natural organic matter and ammonia from surface waters

Operating Bicarbonate-Form versus Chloride-Form Ion Exchange Resins without Regeneration for Natural Organic Matter Removal

“…The average diameter of Purolite A860 resin is of 0.75 mm according to the supplier. Based on previous measurements, the ion exchange capacity is quantified as 0.68 eq/L of resin and the virgin resin is initially loaded with chloride . Batch preconditioning of both chloride-form and bicarbonate-form IX was carried out in a lab-scale 10 L beaker prior to its transfer to pilot-scale packed-bed filters.…”

“…Based on previous measurements, the ion exchange capacity is quantified as 0.68 eq/L of resin and the virgin resin is initially loaded with chloride. 20 Batch preconditioning of both chloride-form and bicarbonate-form IX was carried out in a lab-scale 10 L beaker prior to its transfer to pilot-scale packedbed filters. The preconditioning of chloride-form IX consisted of three steps.…”

“…20,22 Although BIEX proved to be less efficient than a conventional IX filter which was regenerated on a weekly basis (IX: 80% vs BIEX: 62%), this novel mode demonstrated the possibility of significantly reducing the IX brine production (i.e., 331 days without regeneration) while maintaining a high NOM removal. 20 Another alternative to ease brine management is to resort to the use of bicarbonate salt as an IX regenerant (i.e., bicarbonate-form IX) as opposed to chloride salt. Bicarbonate brine can be directly disposed into sewers or, in some cases, the environment as bicarbonate has little impact on flora and fauna.…”

“…Lab-scale experiments indicated that in the absence of regeneration, biodegradation contributed to NOM removal as BIEX achieved a higher dissolved organic carbon (DOC) removal than its abiotic counterpart operated in parallel (BIEX: 60% vs Abiotic-IX: 40%) . BIEX also exceeded NOM removal efficiency of biological activated carbon (BAC) filters at lab-scale (BIEX: 56% vs BAC: 15%) as well as at pilot-scale (BIEX: 62% vs BAC: 5%). , Although BIEX proved to be less efficient than a conventional IX filter which was regenerated on a weekly basis (IX: 80% vs BIEX: 62%), this novel mode demonstrated the possibility of significantly reducing the IX brine production (i.e., 331 days without regeneration) while maintaining a high NOM removal …”

“…19 In an effort to prolong the service time of IX and reduce the production of brine, it has been proposed to operate fixed-bed IX filters over an extended period of time without regeneration to favor biomass development on the surface of IX beads and thereby benefit NOM removal through biodegradation, that is, biological ion exchange (BIEX). 20 Lab-scale experiments indicated that in the absence of regeneration, biodegradation contributed to NOM removal as BIEX achieved a higher dissolved organic carbon (DOC) removal than its abiotic counterpart operated in parallel (BIEX: 60% vs Abiotic-IX: 40%). 21 56% vs BAC: 15%) as well as at pilot-scale (BIEX: 62% vs BAC: 5%).…”