Biodegradation of oxyanions such as perchlorate on ion exchange resins

Abstract

Improved systems and methods for removing the load of perchlorate and other oxyanions off of ion exchange resins through bioregeneration are disclosed. The improved systems and methods rely upon direct contact between the resin and a liquid product containing enrichment cultures of or pure strains of perchlorate-destroying microorganisms. Controlled temperatures also lead to improvements as do upflow conditions leading to bed expansion. These methods can be incorporated into methods for removing perchlorate from aqueous streams.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS[0001]This application claims priority from U.S. Provisional Application Ser. No. 60 / 808,082, filed May 23, 2006, incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention pertains to the field of water treatment and to the use of ion (anion) exchange resins in processes to remove oxyanion contaminants, such as perchlorate ion contaminants, from aqueous streams. These aqueous streams range from domestic, industrial and agricultural water supplies such as drinking water to waste waters, brines and other aqueous flows. More particularly, in preferred embodiments, this invention relates to improvements in methods for biologically removing perchlorate load from perchlorate-loaded ion exchange resins generated in such processes so as to permit reuse or safe disposal of the resins.[0004]2. Background Information[0005]Ammonium perchlorate has been used for the past 50 years a...

AI Technical Summary

Benefits of technology

This process effectively reduces perchlorate loads on ion exchange resins, enabling their safe reuse or disposal, while avoiding the generation of harmful regeneration products and overcoming the limitations of high salt concentrations that inactivate bacteria.

Problems solved by technology

Casual handling of perchlorates and perchlorate-laden effluents by manufacturers and the build up of poorly-contained stockpiles of outdated missile and rocket fuels have resulted in perchlorate contamination of surface water and ground water supplies.

However, state of the art practice does not provide a practical and convenient method for regeneration of the resin after it has been used.

These regeneration difficulties have led to an alternative ion exchange process in which the resin is used once for the adsorption of perchlorate and other oxyanions (i.e. nitrate, arsenate, sulfate) and then thrown away instead of being regenerated and reused.

In both of these processes of the prior art, a difficult-to-deal-with perchlorate-loaded spent resin is formed.

The loaded resin can not be safely discarded in ordinary land fills and the like because of fears of its perchlorate content reentering the environment.

Attempts to bacterially break down the perchlorate content of the concentrated sodium chloride brines formed in conventional regeneration of perchlorate-loaded resins have been unsuccessful.

High salt levels create an osmotic imbalance in cells containing normal levels of cytoplasmic solutes.

This imbalance leads to a loss of water from the bacteria cells and an irreversible retraction of the cytoplasm, which is the cause for the rapid killing of microorganisms which are not salt-tolerant by nature.

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