Annex 4 analytical methods
model description
general description
- acronym
- SimpleTreat
- name
- Sewage Treatment Plant Model
- main purpose
- SimpleTreat 4.1 is an exposure and emission model developed to estimate chemical emission from sewage treatment plants and exposure in surface water within the framework of risk assessment of chemicals. The current version is a revision of SimpleTreat 4.0.9, please see the release note for details. SimpleTreat 4.0 and 4.1 are both updates of SimpleTreat 3.1, which supported the chemical act 30 years ago in the Netherlands and later in the European Union (EU). The revision from v4.0 to v3.1 was necessary to account for more recent scientific insights with respect to behavior of chemicals in domestic sewage and activated sludge.
- homepage
- https://www.rivm.nl/en/soil-and-water/simpletreat
Developer and its nature
- ownership
- Third-party ownership (commercial companies, Member States, other organisations, …)
- ownership additional info
- Dutch National Institute for Public Health and the Environment (RIVM)
- is the model code open-source?
- NO
Model structure and approach with any key assumptions, limitations and simplifications
- details on model structure and approach
- The model assumes steady state and complete mixing of the contaminant in the compartments of a WWTP. It assumes partitioning to follow linear isotherms. The description has limitations on validity for ionic and polar compounds. The mass balance of a contaminant in the various phases and compartments within the WWTP is solved as a system of linear equations.
- model inputs
- Physicochemical properties of the contaminant:
- Air-water partition coefficient
- Degradation rate
- Solids/water partition coefficient
- Operating conditions of the WWTP (particularly the hydraulic loading rate and sludge retention time).
- Physicochemical properties of the contaminant:
- model outputs
- Concentration of the contaminant in the different compartments and phases of the WWTP, including sludge and effluents.
- Percentage of the contaminant mass in the effluents that ends up in the sludge and effluents, and degradation/volatilization removal efficiency (%).
Intended field of application
- policy role
The model can be used to appraise the fate of a chemical undergoing wastewater treatment. This may have obvious, important policy and regulatory implications.
- policy areas
- Environment
- Public health
Model transparency and quality assurance
- Are uncertainties accounted for in your simulations?
- NOT_APPLICABLE - The model is known to be sensitive to certain parameters. No formal sensitivity/uncertainty analysis available.
- Has the model undergone sensitivity analysis?
- NOT_APPLICABLE - The model is known to be sensitive to certain parameters. No formal sensitivity/uncertainty analysis available.
- Has the model been published in peer review articles?
- YES
- Has the model formally undergone scientific review by a panel of international experts?
- NO - The model is scrutinized in the community of practitioners.
- Has model validation been done? Have model predictions been confronted with observed data (ex-post)?
- NOT_APPLICABLE - The model has been applied mostly in a regulatory context. Comparison with observed data requires parameter calibration.
- To what extent do input data come from publicly available sources?
- Based on both publicly available and restricted-access sources
- Is the full model database as such available to external users?
- NO
- Have model results been presented in publicly available reports?
- YES
- Have output datasets been made publicly available?
- NO
- Is there any user friendly interface presenting model results that is accessible to the public?
- YES - The model comes in a format like a spreadsheet.
- Has the model been documented in a publicly available dedicated report or a manual?
- YES
Intellectual property rights
- Licence type
- Non-Free Software licence
application to the impact assessment
Please note that in the annex 4 of the impact assessment report, the general description of the model (available in MIDAS) has to be complemented with the specific information on how the model has been applied in the impact assessment.
See Better Regulation Toolbox, tool #11 Format of the impact assessment report).