In general terms, paper is a sheet of fibers with a number of added chemicals that affect the properties and quality of the sheet. Besides fibers and chemicals, manufacturing of pulp and paper requires large amounts of process water and energy (as steam and electricity). Pulp for papermaking may be produced from virgin fiber by chemical or mechanical means or by re-pulping of recovered paper. A paper mill may utilize pulp made elsewhere (= non-integrated pulp mills) or may be integrated with the pulping operations at the same site (= integrated pulp mills). Kraft pulp mills can be both non-integrated and integrated operations, whereas sulfite pulp mills are normally integrated with paper production.
For the purpose of the Toolkit, processes can be broken down into a number of classes. Although, wood is most commonly used as raw material for pulp making, it should be noted that also non-wood fibers such as cereal straw and reeds are used as raw materials for pulp and paper production. These fibers represent 6.5-11% of the world’s virgin pulp production. In developing countries or countries with limited forestry resources, non-wood fibers make up >35% of the total pulp production (Blanco et al. 2004). One of the major producers of pulp/paper from non-wood fibers is China (Zheng et al. 2001, Zheng et al. 1997). More information on raw materials for pulp and paper manufacture can be found in the BAT&BEP Guidelines.2
The production of pulp is the major source of environmental impacts from the pulp and paper industry.
From pulp and paper mills releases of PCDD and PCDF may occur via the following vectors:
Emissions to air (from burning of lignin and black liquor to generate steam);
Emissions to air from burning wood or bark to generate steam;
Emissions with process water (modern pulp mills operate totally effluent free);
Emissions into the pulp sludge, which may be applied on land, be incinerated or landfilled;
Emissions into the products (= pulp, paper), which enter the market as a valuable product.
In general terms, the process to make paper and paperboard consists of three steps: pulp making, pulp processing, and paper/paperboard making. A detailed description of the process is available in the BAT&BEP Guidelines.3
PCDD/PCDF emission factors are listed according to the activity type in Tables X-X. To assist in estimating releases typical values in terms of μg TEQ/ADt (Air Dry tons) are given in the tables along with typical concentrations in effluent and solids – these can be used if mass flow data are unavailable. The emission factors for the wood fiber plants assume all plants have effluent treatment facilities producing sludge and effluent low in suspended solids. For non-wood, the concentration relates to the raw effluent before treatment.
Annual emissions with wastewater effluents and pulp and paper sludges (= residues) will be calculated by multiplying the concentration in the effluent (in pg TEQ/L) or the concentration in the sludge (in μg TEQ/t dry matter) with the annual discharge or production volume, respectively.
Data for pulp are commonly reported based on Air Dried tons (ADt), which refer to pulp at 90% dryness or 900 kg of bone dry pulp. For paper, the basis is the finished paper at the dryness that results, typically 94-96% dryness. Activity rates may be obtained from various sources, in particular:
Owners/operators of the relevant facilities (by questionnaires);
State, provincial, national and/or international agencies that gather centralized statistical information.
Letter data quality rating is provided for the default emission factors