EnviroSim Announces PetWin 4.1.1

EnviroSim is pleased to announce the release of PetWin 4.1.1. A comprehensive description of the upgrade may be found in a “New Developments in PetWin” document for PetWin 4.1.1 in PDF format. These will help to get you started in PetWin 4.1; more comprehensive information is provided in the user manual.

PetWin 4.1.1 continues to expand the capabilities of wastewater treatment plant simulation with key enhancements to the core model, the model library, and the interface. A focus in this release has been to extend and refine the core Industrial Activated Sludge Digestion Model (ASDMi) model, which builds on the industry-standard BioWin model to include over 100 processes acting on over 60 state variables related to industrial wastewater compounds. In addition to adding many new process rate equations, refinements to the core model have resulted in faster dynamic simulations, particularly for nutrient removal systems.

The most significant ASDMi extension has been to include three mechanisms for modeling nitrous oxide (N2O) production and emission. As a result, PetWin 4.1.1 is a powerful tool for evaluating plant-wide greenhouse gas (GHG) emissions of nitrous oxide, methane and CO2. The basis of the N2O model, and other extensions and improvements to the ASDMi are outlined further below.

New flowsheet elements for trickling filters, thermal hydrolysis (sludge digestion pre-treatment), submerged aerated filters, and sidestream media bioreactors have been added for increased modeling flexibility. Enhancements have been made for several existing flowsheet elements including primary settling tanks, cyclones, and anaerobic digesters.

In this release, we have also greatly enhanced the utility and functionality of PetWin’s internal Notes Editor. Sharing information about your models with your colleagues is an important part of project workflow. Traditionally, many of us have shared “notes” about our models using email. Now there is a better way – using PetWin’s internal Notes Editor!

  • Any notes you add with PetWin’s Notes Editor are now saved internally to the PetWin file, just like all other modeling results. If notes have been added to a file, PetWin automatically displays these when the file is opened, facilitating knowledge transfer.
  • The Notes Editor has gained significant functionality and now has full Rich Text Format (RTF) capability. Project notes can now contain tables, screenshots from the PetWin Album, and other useful formatting components. The notes also can be easily exported to Word, to streamline your project reporting workflow.

The upgrade to 4.1 will not affect older PetWin versions (PetWin 3.1 and earlier) which are separate applications. This means that users can keep their older copies of PetWin.

  1. PetWin Updater will not automatically upgrade PetWin 3.1 to PetWin 4.1.1. You MUST run the full installation from the link provided. Thereafter the PetWin Updater will always be checking that your files are up to date.
  2. We are emailing the registered contact for specific PetWin serial number(s). If an organization has multiple copies or users of PetWin, we would be pleased if the registered contact can advise other users of this new version and these upgrade instructions.


  • Annual License Customers Annual License customers can now upgrade to PetWin 4.1; releases and upgrades are included in the Annual License and distributed electronically. Instructions on how to electronically upgrade to PetWin 4.1.1 can be found here.
  • Perpetual License Customers Perpetual License customers who acquired PetWin after June 1, 2014 will be emailed instructions on how to electronically upgrade to PetWin 4.1 free of charge. If you have not received your upgrade email, or if you are prompted for a code, please contact us. Customers who acquired PetWin prior to June 1, 2014 may order an upgrade here for $4,500.
  • Academic Licenses Academic Licenses can now be upgraded to PetWin 4.1; releases and upgrades are included in the annually renewed license and distributed electronically. Instructions on how to electronically upgrade to PetWin 4.1 can be found here.