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Summary of BIOMOC

       biomoc - A multispecies solute-transport model with biodegradation

       BIOMOC is a two-dimensional model that can simulate the transport
       and biotransformation of multiple reacting solutes.  The program is
       general and flexible, allowing for any combination of biodegradation
       processes.  A number of expressions for biological transformation
       rates have been included as options in the code.  These include
       single, multiple, and minimum Monod kinetics and competitive,
       noncompetitive, and Haldane inhibition.  The kinetic parameters can
       be formulated to simulate zero-order or first-order approximations
       of biodegradation rates.  The growth and decay of several microbial
       populations performing the transformations is also accounted for.
       The microbial growth can be disabled, limited by biomass inhibition,
       or limited by the availability of a specified nutrient.

       BIOMOC is an extension of the U.S. Geological Survey's Method of
       Characteristics (MOC) flow and transport model (Konikow and
       Bredehoeft, 1978; Goode and Konikow, 1989).  The two-dimensional
       transport equation is solved for each solute species and a
       biodegradation reaction term is included.  The flow and transport
       equations are discretized using a rectangular, uniformly spaced,
       block-centered, finite-difference grid.  Implicit finite-difference
       equations are used to solve the flow equation.  The average linear
       flow velocities are then calculated and used to solve the transport
       equation using the method of characteristics and particle tracking.

       Macroscopic fluid substrate, electron acceptor, and cellular
       nutrient concentrations are used to calculate uptake and growth.
       Monod kinetics is used to represent biodegradation uptake that
       depends on a single solute concentration.  For biodegradation
       processes that involve several solutes, two alternate modified Monod
       formulations are included in BIOMOC.  The multiple Monod formulation
       assumes that the biodegradation reaction is limited by the
       concentration of each solute involved in the reaction.  The
       alternative minimum Monod formulation assumes that a single solute
       is limiting the process.  In addition, the Monod parameters can be
       specified to approximate zero-order or first-order biodegradation

       All degradation kinetics formulations include competitive,
       noncompetitive, and Haldane inhibition.  Competitive inhibition is
       used to represent the inhibition of uptake of a secondary substrate
       when the primary substrate is still present.  The noncompetitive
       inhibition formulation is useful for modeling the transition between
       redox zones within contaminant plumes; an example of noncompetitive
       inhibition is the inhibition of an anaerobic biodegradation process
       by the presence of oxygen.  Haldane inhibition is used to model
       toxicity.  The biomass growth rate is proportional to the
       degradation rate.  However, growth may be either turned off or
       limited by a biomass inhibition formulation.

       BIOMOC does not include pore-scale processes and does not account
       for the effect of diffusion into and out of the biophase.  It has
       also been assumed in BIOMOC that the biomass remains attached to the
       sediments.  Pore clogging by biomass growth is not accounted for.

       Version 1.0 1999/03/10 - Initial release

       Input data consist of initial conditions, boundary conditions,
       aquifer properties, and biodegradation parameters.  See
       documentation for details.

       See documentation.

       BIOMOC is written in Fortran 77 with the following extensions:  use
       of variable names longer than 6 characters and use of include files.
       The code has been used on UNIX-based computers and on DOS-based 386
       or greater computers having a math coprocessor.

       Essaid, H.I., and Bekins, B.A., 1997, BIOMOC, A multispecies solute-
          transport model with biodegradation: U.S. Geological Survey
          Water-Resources Investigations Report 97-4022, 68 p.

       Goode, D.J., and Konikow, L.F., 1989, Modification of a method-of-
          characteristics solute-transport model to incorporate decay and
          equilibrium-controlled sorption or ion exchange: U.S. Geological
          Survey Water-Resources Investigations Report 89-4030, 65 p.

       Konikow, L.F., and Bredehoeft, J.D., 1978, Computer model of two-
          dimensional solute transport and dispersion in ground water: U.S.
          Geological Survey Techniques of Water-Resources Investigations,
          book 7, chap. C2, 90 p.

       Operation and Distribution:
          U.S. Geological Survey
          Hydrologic Analysis Software Support Program
          437 National Center
          Reston, VA 20192

       Official versions of U.S. Geological Survey water-resources analysis
       software are available for electronic retrieval via the World Wide
       Web (WWW) at:


       and via anonymous File Transfer Protocol (FTP) from:
         (path: /pub/software).

       The WWW page and anonymous FTP directory from which the BIOMOC
       software can be retrieved are, respectively:


       If you would like to obtain the price of and (or) order paper copies
       of USGS reports, contact the USGS Branch of Information Services at:

                  USGS Information Services
                  Box 25286
                  Denver Federal Center
                  Denver CO 80225

       To inquire about Open-File Reports or Water-Resources Investigations
                  Tel: 303-202-4200; Fax 303-202-4695

       To inquire about other USGS reports:
                  Tel: 303-202-4700; Fax 303-202-4693

       moc(1) - Two-dimensional method-of-characteristics ground-water flow
                and transport model
       moc3d(1) - Three-dimensional method-of-characteristics ground-water
                  flow and transport model

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