SimpleTreat 3.0: a model to predict the distribution and elimination of Chemicals by Sewage Treatment Plants
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Series / Report no.
Open Access
Type
Report
Language
en
Date
1996-01-31
Research Projects
Organizational Units
Journal Issue
Title
SimpleTreat 3.0: a model to predict the distribution
and elimination of Chemicals by Sewage Treatment
Plants
Translated Title
SimpleTreat 3.0: een model ter voorspelling van de
distributie en eliminatie van chemicalien door
rioolwaterzuiveringsinstallatie (rzwi)
Published in
Abstract
Dit rapport beschrijft het spreadsheet SimpelTreat 3.0
een model waarmee de distributie en eliminatie van chemicalien door een
rioolwaterzuiveringsinstallatie (rwzi) kan worden voorspeld. SimpelTreat
3.0 is een verbeterde versie van SimpleTreat, dat ten behoeve van het
Uniform Beoordelingssysteem Stoffen (UBS versie 1.0, 1994) in Nederland
wordt toegepast. Ofschoon aanvankelijk bij dit model de nodige reserves
bestonden, werd het al spoedig geaccepteerd als een nuttig instrument voor
generieke blootstellingsbeoordeling. Thans wordt onderkend dat de
nauwkeurigheid van exposure assessment, met name voor het compartiment
water, grotendeels wordt bepaald door de nauwkeurigheid waarmee de emissie
door rwzi's kan worden voorspeld. In SimpelTreat 3.0 hebben de
geformuleerde transport- en omzettingsprocessen van een chemische verbinding
een breder toepassingsgebied, zowel t.a.v. stofeigenschappen als
scenario's. Emissie van stoffen door een rwzi via slibproduktie, werd
gemodificeerd waarbij rekening werd gehouden met de aan- dan wel de
afwezigheid van voorbezinking van afvalwater. Primaire bezinking wordt veel
toegepast in stedelijke gebieden, waar meestal zeer grote installaties het
onbezonken afvalwater verwerken. Afwezigheid van voorbezinking komt meer
voor in landelijke gebieden waar het overgrote deel gezuiverd wordt, zoals
in Denemarken. Mathematische formuleringen voor de afzonderlijke
lotgevallen van een stof in een rwzi werden herzien. Voor emissie naar
lucht als gevolg van het beluchtingsproces in de aeratietank, is een
verbeterde schatting gemaakt rekening houdend met de gas-film weerstand.
Dit is een meer correcte beschrijving van het gedrag van semi-vluchtige
verbindingen. De invoer en de verwerking van biodegradatiegegevens hebben
echter de meeste veranderingen ondergaan. Modificaties zijn gedeeltelijk
ingegeven door de discussies die hebben plaatsgevonden tijdens de
ontwikkeling van het risicobeoordelingssysteem voor "nieuwe" en "bestaande"
stoffen voor Europese Gemeenschap. Ook recent gepubliceerde
onderzoeksresultaten zijn in toepassing gebracht. Momenteel wordt voor de
EU een tweede versie van UBS voorbereid (USES 2.0). Aangezien de
modelmatige beschrijving van het lot van stoffen in rwzi een sleutelrol
speelt bij de blootstellingschatting, is besloten om voor dit doel
SimpelTreat 3.0 aan te wenden i.p.v. SimpleTreat. Dit rapport dient als
naslagwerk voor SimpelTreat 3.0. De spreadsheet-file op diskette aan dit
rapport toegevoegd werd geschreven in MicroSoft EXCEL.
The spreadsheet SimpelTreat 3.0 is a model to predict the distribution and elimination of chemicals by sewage treatment. Simpeltreat 3.0 is an improved version of SimpleTreat, applied in the Netherlands in the Uniform System for the Evaluation of Substances (USES version 1.0, 1994). Although in the very beginning strong reservations were encountered, the model has become accepted as a useful tool for generic exposure assessment. It is now recognized that the accuracy of exposure assessment, in particular for the water compartment in urban regions, is largely determined by the accuracy with which the chemical fate in sewage treatment plants (STP) can be predicted. This model includes a wider range of operation modes of wastewater purification to account for the variety of communal wastewater scenarios across the EU. Chemical transport and transformation processes also cover a wider range of applications both for compound properties and scenarios. Emission of substances via sludge production was modified to account for the presence and absence of primary sedimentation. The first scenario applies to the urban areas where usually large installations purify the raw wastewater ; the second is more representative for rural regions, where a high percentage of the wastewater goes through treatment installations, for example in Denmark. Mathematical expressions of individual processes, which chemicals may undergo in a STP were critically reviewed. Emission to the air compartment, due to stripping in the aeration tank, has been re-assessed by taking into account the gas-phase resistance. This correction is necessary to better predict the behaviour of semi-volatile chemicals. However, the input of biodegradation data and the way this information is processed have been altered the most. Modifications are partly motivated by the discussions in the course of developing a risk assessment system for "new" and "existing" chemicals in the European Community. Also, results, presented in recent literature, have been implemented. A second version of USES to be applied in the EU, is currently being developed. Since a sewage treatment chemical fate model should cover many scenarios to play its key role in exposure assessment, it was decided to use Simpeltreat 3.0 for this purpose in USES 2.0, instead of SimpleTreat. This report may serve as a reference manual for Simpeltreat 3.0. The electronic version of this spreadsheet file (on accompanying diskette) is written in MicroSoft EXCEL.
The spreadsheet SimpelTreat 3.0 is a model to predict the distribution and elimination of chemicals by sewage treatment. Simpeltreat 3.0 is an improved version of SimpleTreat, applied in the Netherlands in the Uniform System for the Evaluation of Substances (USES version 1.0, 1994). Although in the very beginning strong reservations were encountered, the model has become accepted as a useful tool for generic exposure assessment. It is now recognized that the accuracy of exposure assessment, in particular for the water compartment in urban regions, is largely determined by the accuracy with which the chemical fate in sewage treatment plants (STP) can be predicted. This model includes a wider range of operation modes of wastewater purification to account for the variety of communal wastewater scenarios across the EU. Chemical transport and transformation processes also cover a wider range of applications both for compound properties and scenarios. Emission of substances via sludge production was modified to account for the presence and absence of primary sedimentation. The first scenario applies to the urban areas where usually large installations purify the raw wastewater ; the second is more representative for rural regions, where a high percentage of the wastewater goes through treatment installations, for example in Denmark. Mathematical expressions of individual processes, which chemicals may undergo in a STP were critically reviewed. Emission to the air compartment, due to stripping in the aeration tank, has been re-assessed by taking into account the gas-phase resistance. This correction is necessary to better predict the behaviour of semi-volatile chemicals. However, the input of biodegradation data and the way this information is processed have been altered the most. Modifications are partly motivated by the discussions in the course of developing a risk assessment system for "new" and "existing" chemicals in the European Community. Also, results, presented in recent literature, have been implemented. A second version of USES to be applied in the EU, is currently being developed. Since a sewage treatment chemical fate model should cover many scenarios to play its key role in exposure assessment, it was decided to use Simpeltreat 3.0 for this purpose in USES 2.0, instead of SimpleTreat. This report may serve as a reference manual for Simpeltreat 3.0. The electronic version of this spreadsheet file (on accompanying diskette) is written in MicroSoft EXCEL.
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