Biological treatment of ion-exchange brine regenerant for re-use: A review

Ion-exchange resins are typically selected to target anionic pollutants in drinking water treatment, however, the production of concentrated brine is a significant disadvantage as regulation of its disposal is becoming increasingly strict. Various destructive technologies have been trialled as a replacement for ion exchange, the most notable being biological reduction. Although several full-scale biological processes have been developed for drinking water treatment, regulators remain cautious about the introduction of microbes into the treatment process. Alternatively the bioprocess can be reconfigured to destruct the target anion in the concentrated waste brine, eliminating the bioprocess from direct treatment and reducing the waste volume and salt consumption associated with ion exchange. This paper reviews the difficulties faced when bio-processing complex, highly concentrated brine, evaluates the various process configurations trialled and presents an argument for the integration of membrane technology whilst also providing a précis of the literature available to date on membrane fouling for this application.