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Objective:
The objective of this project is to demonstrate, document, and evaluate the effectiveness of the Anaerobic Percolating Biofilter (APB) technology for treating perchlorate in wastewater generated during rocket motor testing and/or rocket launching. The goal is to collect the data needed to accomplish this objective while developing a design approach for applying the technology across Department of Defense (DoD) sites where solid rocket fuel is tested and deployed.
Technology Description:
Anaerobic percolating biofilters are used to treat a variety of materials and are designed to be simple and reliable with low capital, operation and maintenance costs. APB designs are site-specific and take into account the hydrogeologic setting, the operational schedule, the volumes of wastewater produced, and regulatory considerations.
Research has shown that anaerobic bacteria degrade perchlorate under redox conditions falling between nitrate- and sulfate-reducing levels and that the bacteria capable of perchlorate reduction are a sub-group of nitrate-reducing bacteria that are fairly ubiquitous in nature. These bacteria use perchlorate as a terminal electron acceptor and in the process reduce the oxidation-state of the chlorine atom from +VII to -I. The transformation pathway takes perchlorate through to chloride, with the first removal of an oxygen atom to form chlorate being the rate-limiting step. Fortunately, the biological degradation of perchlorate is straightforward and easily promoted.
The APB technology applies this principle of anaerobic perchlorate reduction in a reactor configuration that is a hybrid between a multimedia filter and a conventional leach-bed reactor. The system includes a contact chamber where the electron donor is added to the wastewater and a fixed-film biofilter that serves as the reactor where perchlorate biodegrades. The reactor packing consists of gravels, sand, and peat in grading sizes over the filter depth. Limestone gravel can be used to buffer the system against pH changes in low alkalinity soils. The biofilter is designed to prevent filter desiccation and oxygenation between loadings so that the anaerobic organisms remain viable. The peat helps to insure this by forming a barrier to evaporation and providing a supply of slow release electron donor that maintains anaerobic conditions between feeds. Batch feeding is necessary to accommodate motor test schedules.
Expected Benefits:
The successful demonstration of the APB technology will provide DoD the following benefits: 1) provision of a low cost, low technical, high reliability technology for specialized applications to achieve compliance with pending U.S. Environmental Protection Agency standards, while allowing continuation of rocket motor-based programs; and 2) development of technology easily adaptable to groundwater remediation.
(Anticipated Project Completion - 2006)
Principal Investigator:
Mr. D. Richard Clark
ICBM System Program Office
OO-ALC/LMES
6054 Dogwood Avenue
Hill Air Force Base, UT 84056
Telephone: (801) 775-2708
Fax: (801) 777-4643
E-mail: richard.clark@hill.af.mil
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