$EPA
 www.epa.gov/nhsrc
technical  BR
            EPANET Extended to  Include Multi-Species Modeling

      Background
      The U.S. EPA's National Homeland Security Research
      Center (NHSRC) Water Infrastructure Protection
      Division (WIPD), headquartered in Cincinnati, Ohio,
      conducts and coordinates research to improve the
      security of drinking water and wastewater treatment,
      distribution, and sources. To counter threats against
      water systems, the NHSRC is developing the Threat
      Ensemble Vulnerability Assessment (TEVA) Program,
      a computer program that models and evaluates water
      system threats and vulnerabilities. TEVA relies on the
      EPA's EPANET hydraulic and water quality software
      package. EPANET has been extended to support
      homeland security research efforts.

      EPANET-MSX
      EPANET is used in  homeland security research to model contamination threats to water systems.
      Historically, EPANET has been limited to tracking the dynamics of a single chemical transported
      through a network of pipes and storage tanks, such as a fluoride used in a tracer study or free
      chlorine used in a disinfection decay study.

      Recently, the NHSRC released a new extension to EPANET called EPANET-MSX (Multi-Species
      extension) that allows for the consideration of multiple interacting species in the bulk flow and on the
      pipe walls. This capability has been incorporated into both a stand-alone executable program as well
      as a toolkit library of functions that programmers can use to build customized applications.

      The multi-species modeling extension to EPANET requires a new MSX input file in which the user
      specifies the mathematical expressions governing the reaction dynamics.  EPANET-MSX parses the
      input file and stores and  structures the data for efficient evaluation.  Newton-Raphson and Runge-
      Kutta  algorithms into the water quality modules are used to solve the differential-algebraic equations
      that specify the reaction dynamics.

      This structure allows users the flexibility to model a wide range of chemical reactions of interest to
      water utilities, consultants, and researchers. EPANET-MSX enables users to model free chlorine
      loss, the formation of disinfection byproducts, nitrification dynamics, disinfectant residuals, and
      adsorption on pipe walls. Homeland security researchers are particularly interested in modeling the
      fate and transport of contaminant threats in drinking water distribution systems.

      MS-EPANET Software and User's Manual
      The EPANET-MSX  software and User's Manual is now available by following the link at:
      http://www.epa.gov/nhsrc/water/teva.html.

      EPANET-MSX is distributed in a compressed zip file that contains a command line executable,
      several libraries of functions, and a User's Manual. The executable can be used to run water quality
      analyses without any additional programming effort.  The function library can be used in conjunction
      with the existing EPANET Programmer's Toolkit to develop customized applications. At this point in
      time, the software has not been integrated into a Windows interface,  but this is expected to happen at
      some point in the future.

                                            (more)

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The software is subject to copyright. It is free software and can be redistributed and/or modified under
the terms of the GNU Lesser General Public License as published by the Free Software  Foundation.
For more information, visit the NHSRC Web site at www.epa.gov/nhsrc, and the TEVA Research
Program site at http://www.epa.gov/nhsrc/water/teva.html.

Technical Contacts: Regan Murray (513) 569-7031,  Murray.Regan@epa.gov
                   Robert Janke (513) 569-7160, Janke.Robert@epa.gov
Communications Contact: Kathy Nickel (513) 569-7955, nickel.kathy@epa.gov
July 2007
EPA/600/S-06/019

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