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Application of Bioreactor Systems to Low-Concentration Contaminated WaterChicago, ILSource: American Water Works Association Research Foundation (AWWARF) Information, December 2000, and AWWARF website, available at http://www.awwarf.com/research/perch.htm. Project Summary: The following text was excerpted from information supplied by American Water Works Association Research Foundation (AWWARF), December 2000, and AWWARF website, available at http://www.awwarf.com/research/perch.htm: This research will evaluate the efficiency of a biological process to reduce perchlorate concentrations of up to 1,000 ug/L to levels of 4-18 ug/L. The research will also evaluate the impact of co-contaminants on process performance, characterized process effluents, and define post treatment requirements. The research is to be completed in 2001. Objective 1. Evaluate the efficiency of a biological process to reduce perchlorate concentrations of up to 1,000 micrograms per liter to drinking water action levels of 4-18 micrograms per liter, 2. Evaluate the impact of co-contaminants, such as nitrate and volatile organic compounds (VOCs), on process performance, and 3. Characterize process effluents and define post treatment requirements. Background A limited number of bioreactor systems have been successfully developed to treat water streams with high concentrations of perchlorate. Examples are the Aerojet process using a GAC/fluidized bed under anoxic conditions and the suspended growth reactor using W.succinogens HAP1 developed by Tyndall A.F.B. The ability of a bioreactor to reduce low concentrations of perchlorate, approximately 1,000 micrograms per liter or less, to drinking water action levels of 4-18 micrograms per liter, is an important knowledge gap. Another important knowledge gap is whether bioreactors developed for removal of nitrate (denitrification) can also be applied to removal of perchlorate. Research Approach Perchlorate contamination of drinking water is currently impacting at least 12 million consumers. Effective treatment technologies for perchlorate removal or destruction are needed immediately. In order to expedite the research process, this project will be undertaken in two phases with the intent that one of the contractors selected for Phase I will continue as the contractor for Phase II. Phase II continuation of the project will be contingent upon several factors, including: success of Phase I, availability of funding for Phase II, and PAC and AWWARF approval of the detailed scope for Phase II work. The AWWA Research Foundation reserves the right to issue a Request for Proposals (RFP) for Phase II work if this is deemed appropriate. The Crafton- Redlands Plume in the Redlands, California area will be required to be investigated as a pilot-scale study site in Phase II. Phase I This project should begin with a brief literature review of potential bioreactor treatment systems potentially applicable to perchlorate contamination. This literature search should include bioreactor systems used for similar contaminants, such as nitrate. Based on this information, bench-scale experiments should be planned perchlorate. Example factors to consider are: 1. Reactor type and configuration (fixed-film, continuous-flow). 2. Influent concentration of perchlorate (between 1,000 micrograms per liter and the action level (18 micrograms per liter). 3. Carbon source and nutrient requirements. 4. Identification of reaction mechanism and possible formation of reaction intermediates. 5. Determine reaction rates. 6. Operating conditions (ranges) (e.g., pH, temperature, residence time). 7. Influence of co-contaminants, including nitrate and VOCs such as trichloroethylene (TCE), perchloroethylene (PCE), etc. It is the intent that these tests be conducted on real water matrices that are as representative as possible of those waters known to be impacted by perchlorate. 8. Effect of influent dissolved oxygen on operating performance. 9. Characterization of the effluent concentrations of perchlorate, chloride, total organic carbon, heterotrophic plate count, pathogens and disinfectant byproduct formation potential, as well as establishing mass balances for the treatment process. 10. Identification of post treatment requirements, especially the need for filtration and disinfection. 11. Estimate costs and scale-up issues. Results of the Phase I work should be summarized in a final report. In addition to documenting Phase I activities and results, this report should also be suitable for use in Phase II activities. The goal of Phase II activities (not directly funded in this RFP) is to further develop design data and operating procedures to accomplish the desired perchlorate removals at pilot-scale. A brief description of currently anticipated Phase II activities is presented below. Additional details concerning Phase II activities will be developed in the course of the Phase I work. Phase II Following completion of the bench-scale work, a separate pilot-scale project should be initiated approximately two years from now. The pilot-scale work will further develop the most promising bench-scale biological treatment system. In general, the pilot-scale work should evaluate:
Additional Info Source: American Water Works Association Research Foundation (AWWARF) Information, December 2000, and AWWARF website, available at http://www.awwarf.com/research/perch.htm. |
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