Multi-cycle bioregeneration of spent perchlorate-containing macroporous selective anion-exchange resin

Ion exchange using perchlorate-selective resin is possibly the most feasible technology for perchlorate removal from water. However, in current water treatment applications, selective resins are used once and then incinerated, making the ion-exchange process economically and environmentally unsustainable. A new concept has been developed involving the biological regeneration of resin-containing perchlorate. This concept involves directly contacting perchlorate-containing resins with a perchlorate-reducing microbial culture. In this research, the feasibility of multi-cycle loading and bioregeneration of a macroporous perchlorate-selective resin was investigated. Loading and bioregeneration cycles were performed, using a bench-scale fermenter and a fluidized bed reactor followed by fouling removal and disinfection of the resin. The results revealed that selective macroporous resin can be employed successfully in a consecutive loading-bioregeneration ion-exchange process. Loss of resin capacity stabilized after a few cycles of bioregeneration, indicating that the number of loading and bioregeneration cycles that can be performed is likely greater than the five cycles tested. The results also revealed that most of the capacity loss in the resin is due to perchlorate buildup from previous regeneration cycles. The results further indicated that as the bioregeneration progresses, clogging of the resin pores results in strong mass transfer limitation in the bioregeneration process.

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► Biodegradation of resin-attached perchlorate is slower than that of the free ion.
► Bioregeneration of ClO4−-laden resin is limited by kinetics and mass transfer.
► ClO4−-laden resins can be bioregenerated and reloaded for at least five cycles.
► A capacity loss of about 15% was observed during bioregeneration.
► Capacity loss is caused by buildup of undegraded ClO4−-in the resin’s center.