Quantifying Enhanced Microbial Dehalogenation Impacting the Fate and Transport of Organohalide Mixtures in Contaminated Sediments

Abstract

Standard Form 298 (Rev. 8/98) REPORT DOCUMENTATION PAGEPrescribed by ANSI Std. Z39.18 Form Approved OMB No. 0704-0188The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to the Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER AUTHOR(S) PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S)12 SERDPThe project investigated techniques and amendments to enhance microbial dehalogenation in sediments contaminated with organohalide mixtures and developed methods and tools to monitor the effectiveness of biostimulation processes. Micro-and mesocosm studies with organohalide-contaminated sediments demonstrated that these contain diverse communities of dehalogenating microorganisms. Dechlorination of historical PCB and PCDD/F contaminant mixtures can be stimulated by addition of amendments and/or bioaugmentation with dechlorinating bacteria. The enhanced dechlorination correlates with increased numbers of dehalorespirer populations and reductive dehalogenase genes. Identification of the specific microbial members associated with PCB-and PCDD/F-dechlorinating activity should allow for better strategies to enhance dehalogenation. The results provide compelling evidence to support further testing and development of biostimulation and bioaugmentation with dehalorespiring bacteria as environmentally less invasive and lower cost alternatives for in situ treatment of PCB impacted sediments. Anacostia microcosms compared to the sum of all di-through deca-chlorinated biphenyls (homolog groups 2 through 10). Analyses of the dry matter content, the total PCB concentration, the average number and percentage of chlorines less than 4 and 6, respectively and in soil samples and commercial Aroclor mixtures. Table 6-2. Analyses of total bacteria, putative dechlorinating and PCB degrading bacteria and the number of dechlorinating bacteria in soil samples. Table 6-3. The potential dechlorination activi...