Actions for TREATABILITY TEST REPORT FOR THE REMOVAL OF CHROMIUM FROM GROUNDWATER AT 100-D AREA USING ELECTROCOAGULATION [electronic resource].

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TREATABILITY TEST REPORT FOR THE REMOVAL OF CHROMIUM FROM GROUNDWATER AT 100-D AREA USING ELECTROCOAGULATION [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy. Office of Environmental Management, 2009.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Additional Creators
Hanford Site (Wash.), United States. Department of Energy. Office of Environmental Management, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
The U.S. Department of Energy (DOE) has committed to accelerate cleanup of contaminated groundwater along the Columbia River. The current treatment approach was driven by a series of Interim Action Records of Decision (IAROD) issued in the mid-1990s. Part of the approach for acceleration involves increasing the rate of groundwater extraction for the chromium plume north of the 100-D Reactor and injecting the treated water in strategic locations to hydraulically direct contaminated groundwater toward the extraction wells. The current treatment system uses ion exchange for Cr(VI) removal, with off-site regeneration of the ion exchange resins. Higher flow rates will increase the cost and frequency of ion exchange resin regeneration; therefore, alternative technologies are being considered for treatment at high flow rates. One of these technologies, electrocoagulation (EC), was evaluated through a pilot-scale treatability test. The primary purpose of the treatability study was to determine the effectiveness of Cr(VI) removal and the robustness/implementability of an EC system. Secondary purposes of the study were to gather information about derivative wastes and to obtain data applicable to scaling the process from the treatability scale to full-scale. The treatability study work plan identified a performance objective and four operational objectives. The performance objective for the treatability study was to determine the efficiency (effectiveness) of hexavalent chromium removal from the groundwater, with a desired concentration of ≤ 20 micrograms per liter ({micro}g/L) Cr(VI) in the effluent prior to re-injection. Influent and effluent total chromium and hexavalent chromium data were collected using a field test kit for multiple samples per week, and from off-site laboratory analysis of samples collected approximately monthly. These data met all data quality requirements. Two of three effluent chromium samples analyzed in the off-site (that is, fixed) laboratory met the performance objective during the continuous operational testing. Effluent hexavalent chromium analyzed by the field laboratory met the performance goal in over 90 percent of the samples. All effluent hexavalent chromium samples during the batch testing with high influent hexavalent chromium concentrations (≈2000 {micro}g/L) met the performance objective. Although the EC system was able to meet the performance goal, it must be noted that it was not uncommon for the system to be operated in recycle mode to achieve the performance goal. The EC unit was sometimes, but not always, capable of a single pass treatment efficiency high enough to meet the performance goal, and recycling water for multiple treatment passes was effective. An operational objective was to determine the volume and composition of the waste streams to enable proper waste designation. The toxicity characteristic leaching procedure (TCLP) concentrations, pH, and free liquids were determined for solid material from the EC electrodes (mechanically removed scale), the filter press, and the tank bottoms for the effluent and waste collector tanks. These data met all data quality requirements. All solid-phase secondary waste streams were found to be below the TCLP limits for the toxicity characteristic, and a pH value within the limits for the corrosivity characteristic. Out of three samples, two (one of scale from the EC unit and one from filter press solids) failed the free liquid (paint filter) test, which is one of the acceptability criteria for Hanford's Environmental Restoration Disposal Facility (ERDF). The solid-phase waste generation rate was about 0.65-gallon of solid waste per 100 gallons of water treated. It is concluded that the solid-phase secondary waste generated from this technology under the conditions at the test site will meet the toxicity and corrosivity criteria for disposal. It is also concluded that with engineering and/or operational improvements, a solid-phase secondary waste...
Report Numbers
E 1.99:doe/rl-2008-13 rev 0
doe/rl-2008-13 rev 0
Subject(s)
Other Subject(s)
Note
Published through SciTech Connect.
09/24/2009.
"doe/rl-2008-13 rev 0"
PETERSEN SW.
Funding Information
DE-AC06-08RL14788
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