Estimation of the Environmental Exposition for Additives in the Rubber ...
RECYCLING UND UMWELT RECYCLING AND ENVIRONMENT Emission Scenario Document Technical Guidance Document risk assessment predicted environmental concentration point source additives in the rubber industry wastewater This paper deals with the estimation of the environmental exposition of rubber chemicals to the hydrosphere. After the entry-relevant life cycle steps and representative point source for the ªreasonable worst caseº have been identified, the emission rate Elocalwater is determined. The sources of wastewater pollution in the rubber industry are described. This contribution describes the technological data and default values required for the determination of the emission rate. The technique for the determination of the PEClocalwater with the aid of the complete scenario (emission, sewage treatment plant, effluent in surface water) is demonstrated in an example.
AbschaÈtzung der Umweltexposition von Additiven in der Kautschuk-Industrie Emissions-Szenario-Dokumente Technischer Leitfaden der EU Risikobewertung Punktquelle Kautschukadditive Abwasser Der vorliegende Beitrag dient zur AbschaÈtzung der Umweltexposition von Kautschukchemikalien in die HydrosphaÈre. Nach der Identifizierung der eintragsrelevanten Lebenszyklusschritte und einer repraÈsentativen Punktquelle fuÈr den ¹reasonable worst caseª wird die Emissionsrate Elocalwater bestimmt. Die Herkunftsbereiche der Abwasserbelastungen in der kautschukverarbeitenden Industrie werden beschrieben. Die zur Ermittlung der Emissionsrate noÈtigen technologischen Daten und Vorgabe-Werte werden dargestellt. Die Vorgehensweise zur Bestimmung des PEClocalwater wird mit Hilfe des Gesamt-Szenarios (Emission, KlaÈranlage, Vorfluter) anhand eines Beispieles dargestellt.
654
Estimation of the Environmental Exposition for Additives in the Rubber Industry M. GraÈfen, K. Hesse, D. PollklaÈsner and W. Baumann, Dortmund
This paper estimates the exposure concentration (release) of additives in the rubber industry and is based on the Emission Scenario Document for the rubber industry [1]. Emission Scenario Documents are part of the concepts for risk assessment management of substances. Due to the notification of new substances and the evaluation of existing substances the EU Member States [2] harmonized the regulations accompanied by a package of Technical Guidance Documents (TGD) of the European Commission. The order of preferences for the risk assessment is as follows [3]: 1. Specific information for the substances from e. g. producers, product registers or open literature 2. Emission Scenario Documents 3. Emission factors (Appendix of the Technical Guidance Document (TGD)) In general the best and most realistic information like described in issue 1 should be used. Unfortunately the availability of representative and reliable monitoring and/or the amount of detail of the information necessary is in most cases not appropriate. For admission of a new substance expert judgement is needed. The exposure assessment of a new substance is made upon Emission Scenario Documents (ESDs) or emission factors. Emission Scenarios take into account specific technological data for the relevant industry. In risk assessment with the emission factors of the appendix of the TGD this is only limited possible. The regulation distinguishes high production volume chemicals (HPVC) and new substances and (other) existing chemicals (NSEC). There are about 1600 HPVC, which are produced in excess of 10 000 tons in the
OECD list. The risk assessment is only made for a fraction of the HPVC and NSEC substances. This is future work. But that means the market volume of a substance is very important for the evaluation of the substance. The exposure concentration of vulcanizing agents, fillers, stabilizer, flame retardants and other additives in the compartment water can be estimated via a generic emission scenario. The assessment of the environmental risk is made step by step according to the life cycle of the substance and is given under realistic worst case conditions. First we have a look on the life cycle of rubber chemicals and possible emission sources. Afterwards the market volumes and shares of important synthetic rubbers are shown to have an idea if the rubbers with regards to the additives are HPVC or NSEC substances. Because of a categorisation the function of additives are described, too. To determine the local exposure concentration a point source is needed. The point source should represent a realistic worst case. The way to select a point source is summarised. In the following Elocalwater (carriage in kg dÿ1 ) will be determined. Now it is possible to estimate the Predicted Environmental Concentration (PEClocalwater ). The principle of the modular estimation of the PEClocalwater and steps of the life cycle are shown in the figure 1. That means the first step is the evaluation of the emission rate of a representative point source in kg per day. In the following steps the volume stream of the sewage treatment plant (STP) Q, the elimination P of the substance and the dilution factor D of the aquatic compartment are considered. As an example a
KGK Kautschuk Gummi Kunststoffe 54. Jahrgang, Nr. 12/2001
Estimation of the Environmental Exposition . . .
KGK Kautschuk Gummi Kunststoffe 54. Jahrgang, Nr. 12/2001
655
Estimation of the Environmental Exposition . . .
Fig. 1. Scenario for the determination of the PEClocalwater (Cinfl : influent concentration, Ceffl : effluent concentration, Q: volume flow of STP, P: elimination in STP, D: dilution factor)
view is given on an anti-ageing agent used in a formulation of a truck tire and the relevant local predicted emission concentration is evaluated.
Life cycle of rubber additives As mentioned in figure 1 a substance used for rubber production passes a number of life cycle steps. A detailed life cycle is shown in figure 2. Each step is characterized in terms of the emission while the substance is passing through
the steps. The production of synthetic ªraw rubberº is counted in the TGD to the industrial category IC 11 (polymers industry) and should be evaluated with emission factors given in the A and B tables of the TGD. The raw material for the production of natural rubber products is provided by countries outside of the European Union (EU) and won't be considered. The substances used in the rubber industry may enter the environment via the product, unused material or wastes. They are only relevant for the compartment water if a direct contact is established. This happens in those processes, where water is used as cooling or heating medium or for the steam vulcanization and therefore has direct contact with the rubber mixture. The contamination through water used in cleaning steps throughout these processes has to be considered, too. Formulation takes place at the site of the basic chemical industry for use in the manufacturing of the rubber product (e.g masterbatches) and also at the site of the rubber industry where the formulation of the rubber mixture is performed. The emission during the production depends on the type of the chemical and the process being used. In this generic scenario the emission of the substance in question will be determined for the formulation and the processing steps of the life cycle. Both life cycle steps are combined because of simplification. The process steps are taken into account via the function of the rubber additive in mixing, mastication, shaping, vulcanization and the finishing. The life cycle step ªindustrial and private useº will not be covered within the ESD, even though a contamination of the environmental compartment water takes place through wear and the subsequent leaching through rainwater [4, 5]. In the life cycle step ªwaste/recoveryº the possible leaching is a potential danger for the compartment water [4].
Emission sources
Fig. 2. Stages in the life cycle of in which emissions into the compartment water may occur
656
The contamination of water in the rubber industry takes place in several areas of the rubber production. Usually whenever water comes into direct contact with the unvulcanized rubber product. This happens during cooling-, steam vulcanization- and cleaning operations. Examples
are the direct cooling during the extrusion, or the direct contact of the vulcanizate with the steam in vulcanization processes where an autoclave is needed. The sources and contaminations of wastewater are detailed in table 1. The water can contain zinc, compounds of which are often used in abherents and cadmium, copper and lead from the galvanization. Storing, weighing, mixing are other possible sources for an exposition [9]. By using wastewater free procedures (indirect cooling, circulation systems, dry cleaning) a release into the compartment water can be avoided. A cascading arrangement of the rinsing baths and an optimised water flow can also decrease the wastewater amount per day. Degreasing is accomplished with the aid of chlorinated hydrocarbons and complex builders like ethylene diamine tetraacetate (EDTA) [4]. The reduction or prevention of dangerous substances from the cleaning operations can be accomplished by degreasing on a watery basis.
Consumption and production of rubber in the EU In the EU only raw synthetic rubber is produced. In the year 1999 the total production of synthetic rubber in the EU was 2 414 000 tons [6]. This amounts to about 25 % of the total production worldwide. The production of natural rubber worldwide has grown from 3 million tons (1980) to 6,7 million tons (1999) [6, 7]. Unlike natural rubber, synthetic rubber is subject to fluctuations in the amount used and produced. The most important types of synthetic rubber are shown in figure 3 in relation to their market percentage synthetic rubbers take up 2/3 of the total rubbers currently used in the industry. These are created from monomers like butadiene, styrene, acrylnitrile and isobutene. They characterize the properties of the rubber. There are of course many more synthetic rubbers (see [4, 8]). This distribution does not fluctuate much over the years, it is assumed to be valid for all EU member states.
Definition of the point source The wastewater from the rubber industry can be divided into the areas sanitary,
KGK Kautschuk Gummi Kunststoffe 54. Jahrgang, Nr. 12/2001
Estimation of the Environmental Exposition . . .
Table 1. Water contamination of different sources in the rubber industry (in mg/l), TI: tire, RP: rubber products1 [9] source
COD2
direct cooling water and abherent contact after mixing
3000 (RP)
direct cooling water after extrusion
5 (RP)
wastewater from the waste air treatment during the production and processing of solutions after pretreatment (stripping)
ca. 6000 35 000 I 1000 (RP)
wastewater from vulcanization in forms as well as subsequent washing and cleaning processes
282 (TI)
wastewater from vulcanization in autoclaves as well as subsequent washing and cleaning processes
65 (RP) 1100 (RP)
C3
SLS2
AOX5
0.1 O (RP)
301 (RP)
233 (RP)
0.23 (RP)
NO2
Ptotal
Pb
Cu
Zn
Cd
1.5 (RP)
0.54 (TI) 1.0 (RP)
< 0.005 (TI)
< 0.05 (RP)
0.06 0.12 0.052 0.084 (TI)
AbschaÈtzung der Umweltexposition von Additiven in der Kautschuk-Industrie Emissions-Szenario-Dokumente Technischer Leitfaden der EU Risikobewertung Punktquelle Kautschukadditive Abwasser Der vorliegende Beitrag dient zur AbschaÈtzung der Umweltexposition von Kautschukchemikalien in die HydrosphaÈre. Nach der Identifizierung der eintragsrelevanten Lebenszyklusschritte und einer repraÈsentativen Punktquelle fuÈr den ¹reasonable worst caseª wird die Emissionsrate Elocalwater bestimmt. Die Herkunftsbereiche der Abwasserbelastungen in der kautschukverarbeitenden Industrie werden beschrieben. Die zur Ermittlung der Emissionsrate noÈtigen technologischen Daten und Vorgabe-Werte werden dargestellt. Die Vorgehensweise zur Bestimmung des PEClocalwater wird mit Hilfe des Gesamt-Szenarios (Emission, KlaÈranlage, Vorfluter) anhand eines Beispieles dargestellt.
654
Estimation of the Environmental Exposition for Additives in the Rubber Industry M. GraÈfen, K. Hesse, D. PollklaÈsner and W. Baumann, Dortmund
This paper estimates the exposure concentration (release) of additives in the rubber industry and is based on the Emission Scenario Document for the rubber industry [1]. Emission Scenario Documents are part of the concepts for risk assessment management of substances. Due to the notification of new substances and the evaluation of existing substances the EU Member States [2] harmonized the regulations accompanied by a package of Technical Guidance Documents (TGD) of the European Commission. The order of preferences for the risk assessment is as follows [3]: 1. Specific information for the substances from e. g. producers, product registers or open literature 2. Emission Scenario Documents 3. Emission factors (Appendix of the Technical Guidance Document (TGD)) In general the best and most realistic information like described in issue 1 should be used. Unfortunately the availability of representative and reliable monitoring and/or the amount of detail of the information necessary is in most cases not appropriate. For admission of a new substance expert judgement is needed. The exposure assessment of a new substance is made upon Emission Scenario Documents (ESDs) or emission factors. Emission Scenarios take into account specific technological data for the relevant industry. In risk assessment with the emission factors of the appendix of the TGD this is only limited possible. The regulation distinguishes high production volume chemicals (HPVC) and new substances and (other) existing chemicals (NSEC). There are about 1600 HPVC, which are produced in excess of 10 000 tons in the
OECD list. The risk assessment is only made for a fraction of the HPVC and NSEC substances. This is future work. But that means the market volume of a substance is very important for the evaluation of the substance. The exposure concentration of vulcanizing agents, fillers, stabilizer, flame retardants and other additives in the compartment water can be estimated via a generic emission scenario. The assessment of the environmental risk is made step by step according to the life cycle of the substance and is given under realistic worst case conditions. First we have a look on the life cycle of rubber chemicals and possible emission sources. Afterwards the market volumes and shares of important synthetic rubbers are shown to have an idea if the rubbers with regards to the additives are HPVC or NSEC substances. Because of a categorisation the function of additives are described, too. To determine the local exposure concentration a point source is needed. The point source should represent a realistic worst case. The way to select a point source is summarised. In the following Elocalwater (carriage in kg dÿ1 ) will be determined. Now it is possible to estimate the Predicted Environmental Concentration (PEClocalwater ). The principle of the modular estimation of the PEClocalwater and steps of the life cycle are shown in the figure 1. That means the first step is the evaluation of the emission rate of a representative point source in kg per day. In the following steps the volume stream of the sewage treatment plant (STP) Q, the elimination P of the substance and the dilution factor D of the aquatic compartment are considered. As an example a
KGK Kautschuk Gummi Kunststoffe 54. Jahrgang, Nr. 12/2001
Estimation of the Environmental Exposition . . .
KGK Kautschuk Gummi Kunststoffe 54. Jahrgang, Nr. 12/2001
655
Estimation of the Environmental Exposition . . .
Fig. 1. Scenario for the determination of the PEClocalwater (Cinfl : influent concentration, Ceffl : effluent concentration, Q: volume flow of STP, P: elimination in STP, D: dilution factor)
view is given on an anti-ageing agent used in a formulation of a truck tire and the relevant local predicted emission concentration is evaluated.
Life cycle of rubber additives As mentioned in figure 1 a substance used for rubber production passes a number of life cycle steps. A detailed life cycle is shown in figure 2. Each step is characterized in terms of the emission while the substance is passing through
the steps. The production of synthetic ªraw rubberº is counted in the TGD to the industrial category IC 11 (polymers industry) and should be evaluated with emission factors given in the A and B tables of the TGD. The raw material for the production of natural rubber products is provided by countries outside of the European Union (EU) and won't be considered. The substances used in the rubber industry may enter the environment via the product, unused material or wastes. They are only relevant for the compartment water if a direct contact is established. This happens in those processes, where water is used as cooling or heating medium or for the steam vulcanization and therefore has direct contact with the rubber mixture. The contamination through water used in cleaning steps throughout these processes has to be considered, too. Formulation takes place at the site of the basic chemical industry for use in the manufacturing of the rubber product (e.g masterbatches) and also at the site of the rubber industry where the formulation of the rubber mixture is performed. The emission during the production depends on the type of the chemical and the process being used. In this generic scenario the emission of the substance in question will be determined for the formulation and the processing steps of the life cycle. Both life cycle steps are combined because of simplification. The process steps are taken into account via the function of the rubber additive in mixing, mastication, shaping, vulcanization and the finishing. The life cycle step ªindustrial and private useº will not be covered within the ESD, even though a contamination of the environmental compartment water takes place through wear and the subsequent leaching through rainwater [4, 5]. In the life cycle step ªwaste/recoveryº the possible leaching is a potential danger for the compartment water [4].
Emission sources
Fig. 2. Stages in the life cycle of in which emissions into the compartment water may occur
656
The contamination of water in the rubber industry takes place in several areas of the rubber production. Usually whenever water comes into direct contact with the unvulcanized rubber product. This happens during cooling-, steam vulcanization- and cleaning operations. Examples
are the direct cooling during the extrusion, or the direct contact of the vulcanizate with the steam in vulcanization processes where an autoclave is needed. The sources and contaminations of wastewater are detailed in table 1. The water can contain zinc, compounds of which are often used in abherents and cadmium, copper and lead from the galvanization. Storing, weighing, mixing are other possible sources for an exposition [9]. By using wastewater free procedures (indirect cooling, circulation systems, dry cleaning) a release into the compartment water can be avoided. A cascading arrangement of the rinsing baths and an optimised water flow can also decrease the wastewater amount per day. Degreasing is accomplished with the aid of chlorinated hydrocarbons and complex builders like ethylene diamine tetraacetate (EDTA) [4]. The reduction or prevention of dangerous substances from the cleaning operations can be accomplished by degreasing on a watery basis.
Consumption and production of rubber in the EU In the EU only raw synthetic rubber is produced. In the year 1999 the total production of synthetic rubber in the EU was 2 414 000 tons [6]. This amounts to about 25 % of the total production worldwide. The production of natural rubber worldwide has grown from 3 million tons (1980) to 6,7 million tons (1999) [6, 7]. Unlike natural rubber, synthetic rubber is subject to fluctuations in the amount used and produced. The most important types of synthetic rubber are shown in figure 3 in relation to their market percentage synthetic rubbers take up 2/3 of the total rubbers currently used in the industry. These are created from monomers like butadiene, styrene, acrylnitrile and isobutene. They characterize the properties of the rubber. There are of course many more synthetic rubbers (see [4, 8]). This distribution does not fluctuate much over the years, it is assumed to be valid for all EU member states.
Definition of the point source The wastewater from the rubber industry can be divided into the areas sanitary,
KGK Kautschuk Gummi Kunststoffe 54. Jahrgang, Nr. 12/2001
Estimation of the Environmental Exposition . . .
Table 1. Water contamination of different sources in the rubber industry (in mg/l), TI: tire, RP: rubber products1 [9] source
COD2
direct cooling water and abherent contact after mixing
3000 (RP)
direct cooling water after extrusion
5 (RP)
wastewater from the waste air treatment during the production and processing of solutions after pretreatment (stripping)
ca. 6000 35 000 I 1000 (RP)
wastewater from vulcanization in forms as well as subsequent washing and cleaning processes
282 (TI)
wastewater from vulcanization in autoclaves as well as subsequent washing and cleaning processes
65 (RP) 1100 (RP)
C3
SLS2
AOX5
0.1 O (RP)
301 (RP)
233 (RP)
0.23 (RP)
NO2
Ptotal
Pb
Cu
Zn
Cd
1.5 (RP)
0.54 (TI) 1.0 (RP)
< 0.005 (TI)
< 0.05 (RP)
0.06 0.12 0.052 0.084 (TI)
