RESEARCH AND ANALYSIS
Table 1 Yield ratios for pulping and papermaking Parameter Range
Reference
Value used
Notes
Chemical pulping Mechanical pulping Recycled pulping
0.40 to 0.55 0.90 to 0.95 0.73 to 0.89
(Martin et al. 2000) (Martin et al. 2000)
0.48 0.93 0.81
Median value Median value
(Stawicki and Read 2010; FAO2016)
See section S1-3 in the supporting information on the Web
Papermaking
— (Eurostat 2016; FAO 2016)
0.95
—
Table 2 Fraction of inputs in five main grades of paper
Outputs
Printing + writing
Sanitary + household
Inputs
Newsprint
Packaging
Other
Recycled pulp Chemical pulp Mechanical pulp
0.68
0.08 0.62
0.34 0.66
0.56 0.22 0.11 0.10
0.27 0.51
—
0.22 0.10
—
— —
—
Non-fibrous
0.30
0.23
in papermaking and cross-checked with European data (CEPI 2012).
recovery), landfill, or the sewer. The paper sector generates pa- per for recycling and industrial waste such as sludge, which is used for energy recovery, non-energy recovery, or landfilled.
Production Matrix Table 2 shows the fractions of pulp and non-fibrous mate- rial inputs in the five main paper grades. The total quantities of pulp, the four paper grades, and “other paper” are taken from the FAO (2016). The total pulp and filler requirement is adjusted for losses in papermaking. The values in table 2 are calculated in a three-step procedure. First, the fraction of recycled pulp in each grade is calculated from paper for recycling utilization reported by the Confederation of European Paper Industries (CEPI) (CEPI 2012) and the yield ratio for recycled pulping. Each fraction for recycled pulp is scaled downward based on the total global amount of recycled pulp, to correct for the dif- ference between European and global recycling levels. Second, the fraction of non-fibrous material are approximations based on Cote and colleagues (2015). The fraction of non-fibrous ma- terials in “other” is calculated from the final difference between the total non-fibrous material use and the use in all other paper grades. Last, in accord with Laurijssen and colleagues (2010), the further input to newsprint is assumed to be mechanical pulp, and for printing + writing and sanitary + household paper it is chemical pulp. The remaining quantity of mechanical pulp is allocated to packaging. The remainder of chemical pulp is allocated to “other.” Postconsumer Waste and Stock Table 3 displays the relevant parameters for calculating post- consumer waste flows. Each year, consumers add some newly purchased paper to stock and dispose of some of their pur- chases or old stock. The net additions to stock are assessed in three ways. First, product lifetime distributions were used. The
Yield Ratios The inputs to chemical and mechanical pulping can be cal- culated from reported global pulp production (FAO 2016) and the yield ratios for pulping (table 1). Martin and colleagues (2000) suggest ranges of yield ratios for pulp relative to the wood input for mechanical pulping and chemical pulping. This anal- ysis uses the median values. Other references such as MacLeod (2007) and Briggs (1994) suggest similar values. The yield ratios for non-wood pulping are assumed similar to those for chemical wood pulping. The recycled pulping yield ratio is calculated by considering the use of paper for recycling per paper grade and the yield ratio per paper grade. The calculation uses the pro- duction matrix in table 2 and recycled pulping yield ratios from Stawicki and Read (2010). It assumes that between 0% and 50% of recycled inputs to packaging are deinked (see section SI-3 in the supporting information on the Web). Yield ratios for papermaking are dependent on the paper grade that is being produced and can vary significantly per pa- per product. The papermaking yield ratio is therefore derived from aggregate waste paper losses and total paper production in the pulp, paper, and print sector in the European Union (EU) 28 (Eurostat 2016; FAO 2016). These losses are recycled and part of the total global paper for recycling quantity reported by the FAO. The resulting yield ratio is very close to the value in the International Energy Agency (IEA) (IEA 2007, 264) and used by Allwood and colleagues (2010). It should be noted that these wastes result mostly from paper converting and printing and do not constitute inefficiencies in paper mills. The quantity of non-fibrous filler materials is calculated from the final differ- ence between pulp inputs, conversion losses, and paper outputs
Van Ewijk et al. , Global Paper Flows, Recycling, Material Efficiency 3
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