Emission factors

Description

In general, it is well known that the input of processes very often determine the output and emissions respectively. The cleaner production approach follows this basic recognition and promotes pollution prevention at source. According to this approach, in Germany, with respect to emissions to air, a so-called emission factor concept has been developed in co-operation between public authorities (national and federal states level), the German Association of textile finishing industry (TVI-Verband) and the Association of textile auxiliary suppliers, (TEGEWA). The emission factor concept concerns facilities for textile finishing (including drying devices) by heat setting, thermosol processes, coating, impregnation, and finishing. The aim of the concept is to minimise the air pollution potential of the applied textile auxiliaries and thus minimising emissions to air. A further aim of the concept is to receive clarity and transparency, knowledge and a better control on the emissions of the large amount of auxiliaries and recipes.
Normally, emissions are regulated by emission mass concentrations (mg substances/m3 air) and emission mass flows (g substances/h). The emission factor-copncept defines substance emission factors and textile substrate-based emissions factors.
 

Substance emission factors

The substance emission factor is defined as the amount of organic and inorganic substances in gram which can be released under defined process parameters (curing time, temperature, substrate) from one kg of auxiliary.
There is to differentiate between:
  • fc giving the total emissions of organic substances expressed as total content of Carbon;
  • and fs giving the emission of a specific substance in case of more toxic or carcinogenic organic substances or in the case of particular inorganic substances like ammonia, hydrogen chloride.
The substance emission factors has to be provided as product information (further to information in Material Safety Data Sheets) from the supplier (chemical industry) to the user (textile finishing industry). All substances according to class I 5.2.5 TA-Luft (German Air Act) exceeding 500 ppm in the auxiliary have to be declared. In addition, information on substances classified under item 5.2.7.1 TA-Luft exceeding 10 ppm and information on inorganic substances classified under 5.2.4 TA Luft is obligatory.
They are either measured or calculated by a concept of the chemical industry. It is important to know, that in more than 90% of all cases the single components behave additionally.
 

Textile substrate-based emission factor

The textile material based emission factor is defined as the amount of organic and inorganic substances in gram which can be released under defined process parameters from one kg of textile material in
  • WFc: g organic C/kg textile substrate
  • WFs: g special substances/kg textile substrate in case of more toxic or carcinogenic organic substances or in the case of particular inorganic substances like ammonia, hydrogen chloride.
 

Main achieved environmental benefits

The concept can be characterised as a self-learning integrated system to control and prevent air emission in textile finishing. Already during product and process design the system can be applied successfully.
In detail the main advantages are:
  • Comparability of emission potential of auxiliaries (g emission/kg auxiliary)
  • Comparability of emission potential of processes (g emission/kg textile)
  • Information on and substitution of the recipes with a high emission potential
  • Pre-calculation of emission potential of finishing recipes
  • Identification of the main sources for process emission (proper priority setting!)
  • Air/textile ratio (m³/kg) can be reduced (energy saving!)
As a result of the concept, the following limit values can be met in textile finishing industry and are obligatory in Germany:
  • 0.8 g organic C/kg textile (for organic substances according to 5.2.5 TA Luft), if the mass flow is equal to or higher than 0.8 kg C/h
  • 0.4 g substance/kg textile (for substances categorised in class I item 5.2.5 TA-Luft (formaldeyde etc.)), if the mass flow is equal to or higher than 0.1 kg/h
  • special limit values for carcinogenic and inorganic substances