Grantee Research Project Results
2004 Progress Report: Reactive Transport Modeling of Metal Removal From Anaerobic Biozones
EPA Grant Number: R829515C010Subproject: this is subproject number 010 , established and managed by the Center Director under grant R829515
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Center for Comprehensive, optimaL, and Effective Abatement of Nutrients
Center Director: Arabi, Mazdak
Title: Reactive Transport Modeling of Metal Removal From Anaerobic Biozones
Investigators: Figueroa, Linda , Shackelford, Charles D. , Wildeman, Thomas
Institution: Colorado School of Mines , Colorado State University
EPA Project Officer: Aja, Hayley
Project Period: October 1, 2003 through September 30, 2006
Project Period Covered by this Report: October 1, 2003 through September 30, 2004
RFA: Hazardous Substance Research Centers - HSRC (2001) Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management
Objective:
The overall objective of this research project is to calibrate a model to describe the long-term microbial activity in anaerobic biozones. We postulate that the proper design point for anaerobic biozones is characterized by the quasi-steady state that develops after 6 to 9 months of operation. Thus, it is important to calibrate the model based on the post-startup conditions expected. Post-startup conditions are characterized microbially by a balanced consortium of cellulolytic fermenters, sulfate reducers, and methanogens as well as substrate availability via the hydrolysis of complex organic polymers (e.g., cellulose). The specific objectives of this research project are to:
- develop and test computer code for the heterogeneous component of a reactive transport model with a biomodule;
- calibrate model elements with controlled batch and column experiments;
- and validate the model with field columns under variable influent temperature and metal concentrations.
Progress Summary:
The numerical model has been designed to work within the MT3DMS environment as an additional package that can be invoked when desired. The effects of preferential flow and of biotic transport influenced by the activity of sulfate-reducing bacteria have been combined into this modeling environment. Based on the flow results, multispecies transport and fate have been simulated using MT3DMS with the new "biotic package." The performance of sulfate-reducing biozones applied to the remediation of acid-mine drainage have been assessed under iron sulfide precipitation conditions using column data from the literature. Cellulose hydrolysis was identified as the rate-limiting step as part of the previous research project (R829515C003). The overall rate of sulfate reduction thus ultimately is controlled by the activity of the cellulolytic organisms. We therefore are focusing the initial batch experiments on characterizing the cellulose-hydrolyzing fermenter (Cellulomonas flavigena, ATCC482 ). The baseline kinetics of C. flavigena have been established for the hydrolysis product glucose. The inhibitory effect of metals is being studied using glucose as the growth substrate for C. flavigena, as the growth kinetics on cellulose are slow. The effect of zinc on C. flavigena kinetics has been established in the absence of organic ligands. In the previous research project (R829515C003), we observed that zinc was not inhibitory to the columns at 500 mg/L during the startup period, and we postulate that the presence of organic ligands mitigated the inhibitory effect. We have observed that zinc concentrations as low as 20 mg/L can inhibit the activity of the cellulolytic fermenter. The measurement of the remaining available solid-phase organic (e.g., cellulose) has emerged as a key element for model calibration and understanding anaerobic biozone longevity. As a part of the model calibration, the change in cellulose composition with time of column and field systems is being evaluated. The field column setup has been redesigned to include a limestone pretreatment unit. The oxic state of the water from the Argo Tunnel precludes the direct treatment of the mine water, as the iron hydroxide floc rapidly clogs the anaerobic column. A pretreatment unit with two nominal sizes of limestone gravel currently is being tested (fall 2004). The optimized pretreatment unit and the columns will be restarted at the Argo Tunnel water treatment plant in January 2005.
Future Activities:
The first objective was completed in Year 1 of the project. The second and third objectives were initiated in Year 1 of the project and will be completed in Year 2 of the project.
Publications/Presentations: See the list of publications/presentations included in the 2004 Annual Report Summary for R829515, which is the overall report for the Rocky Mountain Regional Hazardous Substance Research Center.
Supplemental Keywords:
Technical Outreach Services for Communities, TOSC, Technical Assistance to Brownfields, TAB, groundwater, industry sectors, waste, water, ecological risk assessment, ecology, ecosystems, ecology and ecosystems, environmental chemistry, environmental engineering, geology, geochemistry, toxicology, microbiology, hazardous, hazardous waste, mining-NAIC 21, selenium, acid mine drainage, acid mine runoff, aquatic ecosystems, arsenic, contaminant transport, contaminated sediments, contaminated marine sediment, contaminated waste sites, contaminated sites, contaminated soil, field monitoring, mining-impacted runoff, sediment transport, stream ecosystems, suspended sediment, sediments, mining, remediation, metal mobility, subsurface, extraction of metals, heavy metals, leaching of toxic metals, metal release, metal wastes, metals, metals-contaminated soil, mining wastes, remediation technologies, risk assessment,, RFA, Industry Sectors, Scientific Discipline, INTERNATIONAL COOPERATION, Waste, TREATMENT/CONTROL, Waste Treatment, Contaminated Sediments, Remediation, Mining - NAIC 21, Hazardous Waste, Bioremediation, Ecological Risk Assessment, Environmental Engineering, Hazardous, Geology, risk assessment, anaerobic treatment, contaminant transport, fate and transport modeling, microbial degradation, permeable reactive barrier, sulfate reducing bacterium, contaminated waste sites, suspended sediment, biodegradation, runoff, sediment transport, stream ecosystems, acid mine drainage, remediation technologies, natural organic matter, field monitoring, transport models, mining, treatment, aquatic ecosystems, treatment technology, anaerobic degradation, anaerobic microbial processes, groundwater, heavy metals, mining impacted watershed, mining wastes, redox, acid mine runoffRelevant Websites:
http://www.engr.colostate.edu/hsrc/ Exit
Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R829515 Center for Comprehensive, optimaL, and Effective Abatement of Nutrients Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R829515C001 Redox Transformations, Complexation and Soil/Sediment
Interactions of Inorganic Forms of As and Se in Aquatic Environments: Effects
of Natural Organic Matter
R829515C002 Fate and Transport of Metals and Sediment in Surface Water
R829515C003 Metal Removal Capabilities of Passive Bioreactor Systems: Effects of Organic Matter and Microbial Population Dynamics
R829515C004 Evaluating Recovery of Stream Ecosystems from Mining Pollution:
Integrating Biochemical, Population, Community and Ecosystem Indicators
R829515C005 Rocky Mountain Regional Hazardous Substance Research Center
Training and Technology Transfer Program
R829515C006 Technical Outreach Services for Communities and Technical Assistance to Brownfields
R829515C007 Evaluation of Hydrologic Models for Alternative Covers at Mine Waste Sites
R829515C008 Microbial Reduction of Uranium in Mine Leachate by Fermentative and Iron-Reducing Bacteria
R829515C009 Development and Characterization of Microbial Inocula for High-Performance Passive Treatment of Acid Mine Drainage
R829515C010 Reactive Transport Modeling of Metal Removal From Anaerobic Biozones
R829515C011 Assessment of Electrokinetic Injection of Amendments for Remediation of Acid Mine Drainage
R829515C012 Metal Toxicity Thresholds for Important Reclamation Plant Species of the Rocky Mountains
R829515C013 An Improved Method for Establishing Water Quality Criteria for Mining Impacted Streams
The 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.