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This study was part of a joint research project between the University of Houston (UH)and Montgomery Watson Harza (MWH). The ultimate goal of the project was to developa combined ion-exchange and biological treatment process for perchlorate removal fromdrinking water. The discussion in this paper focuses on perchlorate reduction in ion-exchangespent brine. The objectives were to: investigate perchlorate and nitratereduction in actual ion-exchange spent brine; and, to determine the required conditionsto stabilize rapid microbial perchlorate reduction in ion-exchange spent brine.Actual ion-exchange spent brine (6% NaCl) was collected from the MWH pilot plantlocated in La Puente in southern California. The spent brine was kept in the dark, at 4 degrees Cprior to use. The brine wastreated by sparging with oxygen-free nitrogen gas for 1 hour as well as an addition of 1.5times the stoichiometric acetate requirement and adjustment of the pH to ~7.A culture developed in previous research and maintained by feeding it perchlorate in asynthetic medium with 3% NaCl was used as inoculum for this research. The culture wasfed spent brine diluted to 3% NaCl as a sequencing batch reactor (SBR): after theperchlorate and nitrate were reduced, the culture was allowed to settle for 1-2 hours, 40-60% of the supernatant was withdrawn and replaced with 3% diluted spent brine. Includes 7 references, table, figures.

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Edition: Vol. - No. Published: 06/17/2004 Number of Pages: 9File Size: 1 file , 330 KB