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A disadvantage of using separation-based perchlorate treatment technologies (e.g. ion exchange or membranes) is that they produce a perchlorate-laden concentrate that must be disposed orfurther treated. "Conventional" biological processes can be used to treat perchlorate residualsbut typically require a dedicated deoxygenation step, inoculation with exogenous salt-tolerantbacteria, long residence times due to high solution salinities, and the addition of a costly exogenous substrate such as ethanol. A novel approach for treating perchlorate residuals is toblend them with scalped municipal wastewater followed by treatment in a fixed-bed (FXB)bioreactor. The municipal wastewater decreases the bulk dissolved oxygen (DO) concentration(DO inhibits perchlorate degradation), decreases solution salinity (salinity decreasesbiodegradation kinetics), and provides the requisite substrate and bacteria. This paper discusses a six-month pilotstudy investigating the application of this treatment concept to perchlorate-laden electrodialysisreversal (EDR ) concentrate. The study demonstrated that: perchlorate removal to below detection (~4 g/L) can be achieved and sustained in a FXB bioreactor using blend ratios around 0.5(wastewater:EDR concentrate) and empty-bed contact times (EBCTs) as low as 10 minutes; the process is robust with respect to system upsets; and, that granular activated carbon (GAC)with an effective size of approximately 2 mm was optimal as a biogrowth support medium.

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Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 4 File Size: 1 file , 750 KB