Bioplume III is a two-dimensional, finite difference model for simulating the biodegradation of hydrocarbons in groundwater. The model simulates both aerobic and anaerobic biodegradation processes in addition to advection, dispersion, sorption and ion exchange. Bioplume III simulates the biodegradation of organic contaminants using a number of aerobic and anaerobic electron acceptors: oxygen, nitrate, iron (III), sulfate, and carbon dioxide.
Bioplume III is based on the U. S. Geologic Survey (USGS) Method of Characteristics Model (MOC) dated July 1989 (Konikow and Bredehoeft). The Bioplume III code was developed primarily to model the natural attenuation of organic contaminants in groundwater due to the processes of advection, dispersion, sorption and biodegradation. Bioplume III solves the transport equation six times to determine the fate and transport of the hydrocarbons and the electron acceptors/reaction byproducts. For the case where iron (III) is used as an electron acceptor, the model simulates the production and transport of iron (II) or ferrous iron.
Three different kinetic expressions can be used to simulate the aerobic and anaerobic biodegradation reactions. These include first-order decay, instantaneous reaction and Monod kinetics. The principle of superposition is used to combine the hydrocarbon plume with the electron acceptor plume(s).
Borden and Bedient (1986) developed the Bioplume I model. Bioplume I is based on the assumption that aerobic biodegradation of hydrocarbons is often limited by the availability of dissolved oxygen in groundwater aquifers. Borden and Bedient simulated the aerobic biodegradation of hydrocarbons as an instantaneous reaction between the hydrocarbon and oxygen. Rifai et al. (1988) developed the Bioplume II model by incorporating the concepts developed by Borden and Bedient into the USGS two-dimensional solute-transport model MOC (Konikow and Bredehoeft, 1978). The Bioplume II model tracks two plumes: oxygen and the hydrocarbon. The two plumes are superimposed to determine the resulting concentrations of oxygen and hydrocarbon at each time step. Anaerobic biodegradation in Bioplume II was simulated as a first-order decay in hydrocarbon concentrations.
Major differences between Bioplume II and Bioplume III include:
- Bioplume III runs in a Windows95 environment whereas Bioplume II was mainly developed in a DOS environment.
- Bioplume III has been integrated with a modified version of a sophisticated groundwater modeling platform known as EIS.
Intrinsic Remediation studies are data intensive and require the applicant to make the case that natural attenuation is occurring at a site and that it will persist over time. To help the environmental professional with the data management, visualization, and decision-making tasks involved, the Air Force adopted the EIS Graphical User Interface Platform. EIS (Environmental Information System) is the latest integrated software platform under Windows 95 in which to register, sort, and evaluate the site-specific data of the physical processes influencing the groundwater migration of organic contaminants.
EIS is developed around the following integrating technologies:
- Object-based simulation environment
- Control tools for the creation of a spatial and temporal data base (4 dimensions)
- A patented Macro engineering framework for managing different algorithmic solutions
- Graphics that are embedded in a kriging scheme automatically adjusting to the required spatial resolution
- Open software architecture allowing a cost-efficient customization (other algorithmic solutions, link to other GIS systems) and expansion of the platform (support of different peripheral and field monitoring devices)
- Integration and quantification of the simulation and data processing error to the risk of health hazard
Naturally occurring biological processes can significantly enhance the rate of organic mass removal from contaminated aquifers. Biodegradation research performed by Rice University, government agencies, and other research groups has identified several main themes that are crucial for future studies of natural attenuation:
- The relative importance of groundwater transport vs. microbial kinetics is a key consideration for developing workable biodegradation expressions in models. Results from the United Creosote site (Texas) and the Traverse City Fuel Spill site (Michigan) indicate that biodegradation is better represented as a macro-scale wastewater treatment-type process than as a micro-scale study of microbial reactions.
- The distribution and availability of electron acceptors control the rate of in-situ biodegradation for most petroleum release site plumes. Other factors (e.g., population of microbes, pH, temperature, etc.) rarely limit the amount of biodegradation occurring at these sites.
Naturally occurring biological processes can significantly enhance the rate of organic mass removal from contaminated groundwater aquifers. Biologically mediated degradation reactions are oxidation/reduction (redox) reactions involving the transfer of electrons from the organic contaminant compound to an electron acceptor. Oxygen is the electron acceptor for aerobic metabolism whereas nitrate, ferric iron, sulfate and carbon dioxide serve as electron acceptors for alternative anaerobic pathways.
The Bioplume III package includes the source code, executable version, and technical support.