Grantee Research Project Results
1997 Progress Report: Bioavailability and Biostabilization of PCBs in Soil
EPA Grant Number: R825365Title: Bioavailability and Biostabilization of PCBs in Soil
Investigators: Luthy, Richard G. , McNamara, Sean W.
Current Investigators: Luthy, Richard G. , Dzombak, David A. , McNamara, Sean W.
Institution: Carnegie Mellon University
EPA Project Officer: Aja, Hayley
Project Period: January 1, 1997 through December 31, 1999
Project Period Covered by this Report: January 1, 1997 through December 31, 1998
Project Amount: $499,056
RFA: DOE/EPA/NSF/ONR Joint Program on Bioremediation (1996) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The objective of this study is to investigate the mobility of polychlorinated biphenyls, PCBs, in soils and soil/sludge materials through the development of novel field sampling methods. By advancing scientific knowledge in this area, the new sampling techniques will yield improved estimates of the potential release of residual PCBs in soil. This knowledge will provide further insight into the concept of biostabilization, which envisions that contaminated materials can be actively, and passively, biotreated to remove a large fraction of potentially mobile and bioavailable organic contaminants, thus reducing risk.
This work entails three primary tasks:
Design and evaluate sampling devices to monitor the slow release of PCBs in field soils, sludges, and pilot-scale land biotreatment units.
Perform field and laboratory assessments of PCB leachability from field soils, including biotreated soil/sludge mixtures
Assess the potential for reduction in PCB mobility that may occur in land biotreatment units operated under intrinsic conditions following active biotreatment and examine how this reduction affects risk.
This work is being performed in collaboration with the Aluminum Company of America (Alcoa) in Pittsburgh, PA and Massena, NY, and builds on prior studies between Carnegie Mellon University and Alcoa. Testing will be performed in various site soils at the Massena facility, including that in the field biotreatment units. The data from the field biotreatment units will provide information on how leachability of residual PCBs occurs in subsequent years under passive conditions following active land biotreatment. The impact of the research will be to link a rational model for bioavailability for aged samples with practical measurements relevant to bioremediation engineering practice, and to use those measurements to assess the extent that biostabilization reduces risk and uncertainty in risk assessment.
Progress Summary:
Over the past calendar year, most of the research has focused on Task 1 the development of the sampling technique/device. A thorough literature review was performed to ascertain whether any existing sampling techniques for unsaturated soils could be easily modified to suit our application. The search revealed several deficiencies in existing techniques; the most important being that none simultaneously provided for both a target organic chemical and water accessed mass-balance.
A new sampling device has been developed to address this problem. This device uses a porous cylindrical interface, a sorbent material (i.e. chromatography resin, C18 silica, granular activated carbon, etc.), and a fiberglass wick. The capillarity of the wick provides a passive suction that draws available soil water through the porous interface and sorbent material. PCBs are captured on the sorbent, while water entering the device is collected from the wick at some distance away from the sampling location.
Laboratory research has focused on evaluating the hydraulic performance of this device in various soils across the range of expected soil moisture and flux conditions. A complete computer-aided data acquisition/signal conditioning system was developed for this purpose. This measurement system allows for testing and optimization the various sampler parameters, including wick length, sorbent material properties, and interface porosity. Once optimized for the soil of interest, the sampling device should allow for sampling pore water even under very low soil moisture conditions.
Future Activities:
Research is expected to continue over the summer to optimize the hydraulic performance of the sampler. Additional laboratory tests are planned to characterize the efficiency of chemical capture and to develop a standard sampling and extraction technique for the device. Laboratory results will be compared to those predicted using an unsaturated flow and transport model HYDRUS-2D. Field trials are expected to begin in late summer, proceed until late October, and resume in the Spring of 1999.
Journal Articles:
No journal articles submitted with this report: View all 7 publications for this projectSupplemental Keywords:
bioremediation, bioavailability, biostabilization, polychlorinated biphenyls., RFA, Scientific Discipline, Toxics, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Contaminated Sediments, exploratory research environmental biology, Remediation, Environmental Chemistry, Ecosystem/Assessment/Indicators, Chemical Mixtures - Environmental Exposure & Risk, Ecosystem Protection, Chemistry, HAPS, chemical mixtures, Ecological Effects - Environmental Exposure & Risk, Ecological Effects - Human Health, Bioremediation, Biology, Engineering, Ecological Indicators, risk assessment, fate and transport, fate, biostabilization, biostabilization of PCBs, contaminant transport, contaminated sediment, PCBs, biodegradation, hydraulic oils, chemical transport, kinetic studies, land biotreatment, chemical contaminants, bioremediation of soils, contaminants in soil, environmentally acceptable endpoints, models, vadose zone, physicochemicalRelevant Websites:
http://www.ce.cmu.edu/~mcnamara/RESEARCH/overview.htm
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Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.