Investigation on the input, formation and fate of polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) in the pulp and paper industry

Chemosphere,Vol. 29, Nos. 9-11, pp. 1987-1994, 1994

Pergamon 0045-6535(94)00325-4

Copyright © 1994 Elsevier Science Ltd Printed in Great Britain. All fights reserved 0045-6535/94 $7.00+0.00

INVESTIGATION ON THE INPUT, FORMATION AND FATE OF POLYCHLORINATED DIBENZODIOXINS (PCDDs) AND DIBENZOFURANS (PCDFs) IN THE PULP AND PAPER INDUSTRY

Helmut Santl. Ludwig Gruber, Elke Stfhrer Fraunhofer-Institute for Food Technology and Packaging, Schragenhofstr. 35, 80992 Munich, Germany

Keywords Polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), paper industry, pulp, formation, mass balances

ABSTRACT In 1991 and 1992 an extensive investigation on the input, formation and fate of polychlorinated dibenzodioxins and dibenzofurans in the German pulp and paper industry was carried out. The PCDD/F levels in papers and paperboards have decreased within the last years. The measured values depending on the matrix ranged from 0.17 to 11.53 ng I-TE/kg (ppt). The PCDD/F mass balances of 13 pulp and paper mills showed no formation of PCDD/Fs in any part of the paper or paperboard manufacturing process. INTRODUCTION Since the mid 80's the possibifity of the formation of polychlorinated dibenzofurans (PCDFs) and dibenzodioxins (PCDDs) in the pulp industry using chlorine bleaching has been known/1-5/. In the past few years some very detailed studies investigating the pulp bleaching process with chlorinated substances were published 16-9/. In 1991 and 1992 the first systematic investigation on the input, formation and fate of PCDD/Fs in paper mills was carried out. For this study a great number of samples were taken at 11 paper mills and two new pulp mill pilot plants. A total of about 200 PCDD/F analyses of raw materials, intermediates, final products as well as stock additives, waste waters and sludges were performed.

1987

1988

METHODS The investigations can be subdivided into two parts. The first part was an actual survey on the occurrence of PCDD/Fs in the most abundant types of papers and paperboards. Therefore, 51 paper and paperboard samples produced in Germany between 1991 and 1992 were analysed. In the second and main part of the study the complete PCDD/F mass balances of pulp and paper mills were investigated. To get knowledge about the input and fate of PCDD/Fs in large-scale production processes mass balancing has been found to be an excellent method. The complete balance consisted of three steps. First, samples were taken throughout the whole production process (all inputs, intermediates, outputs) and selected samples were analysed. Then, in combination with the corresponding quantities or the stock flows, respectively, the PCDD/F amounts in all in- and outputs were calculated and balanced. Finally, the congener pattern of all inputs, the corresponding intermediates and of the final products were compared with each other. If the mass balance (output/input ratio) was fullfiUed and the pattern showed no differences, it could be concluded that there is no formation of PCDD/Fs throughout the whole production process. Altogether 13 pulp and paper mills were investigated including two pulp pilot mills working with new technologies, four mills producing LWC-(light weight coated)papers, two mills each producing corrugated papers or recycling paper and one mill producing SC-(supercalandered)paper, folding box board or solid fiber board, respectively. About 220 samples of raw materials, intermediates, stock additives, waste waters and sludges were collected in the pulp and paper mills. The analytical methods have been published in detail/I0, 11/. All results are given in I-TE per kg dry mass including all non-detectable congeners at half of their detection limits. RESULTS AND DISCUSSION

Occurrence of PCDD/Fs in Papers and Paperboards The PCDD/F results of the 51 paper and paperboard samples are summarized in Table 1. The values ranged from 0.17 to 11.53 ng I-TE/kg (ppt) with a mean value of 3.8 ng I-TE/kg. Products, which were completely produced from recycled pulp - like solid fiber boards, corrugated papers and most samples of folding box board - showed PCDD/F levels of approximately 5 to 11 ppt I-TE. Samples produced in 1992 showed slightly lower levels (5 to 7 ppt I-TE) than products from 1991. In recycling papers consisting of deinked fibers lower amounts were measured (I. 12 to 3.24 ppt I-TE). Papers and paperboards consisting only of primary fiber material (virgin pulp bleached with chlorinated substances or thermomechanical pulp), e.g. SC-papers, LWC-papers, wood free printing papers, showed values from 0.17 to 1.65 ppt I-TE for a sulfite wrapping paper sample. In connection with this, it should be emphasized that in general a noticeable decrease of the PCDD/F levels could be observed in all types of papers compared to earlier

1989 results. In 1989 we found 1.9 to 56.2 ng I-TE/kg in samples of the same paper types (Table 1). The PCDD/F levels decreased on average by about a factor of four over two to three years. In some cases the measured values were more than twenty times lower. Table 1: PCDD/F concentrations in papers and paperboards produced in Germany in 1991/92 Type of paper or paperboard

Number of samples

Range

SC-Paper

2

0.24 - 0.28

0.26

LWC-Paper

8

0.27- 1.25

0.49

Wood-Free Printing Paper

3

0.17 - 1.00

0.49

Hygienic Paper

8

0.19 - 2.57

0.91

Newsprint

3

1.48 - 2.73

1.96

Recycling Paper

5

1.12 - 3.24

2.37

Sulfite Wrapping Paper

2

1.65 a - 9.13

5.39

Folding Box Board

5

0.27 a - 10.15

5.04

'Solid Fiber Board

4

5.27 - 11.42

8.69

Corrugated Paper

11

5.64 - 11.53

8.60

All types

51

0.17 - 11.53

3.79

Mean

in ng I-TE/kg'(ppt)

Paper and paperboard (produced in 1989) All types

18

1.90 - 56.2

13.8

incl. all non-detectable congeners at half of their detection limits a produced only out of primary fiber material SC-Paper: supercalendered paper LWC-Paper: light weight coated paper

An important change in the congener pattern could be observed as well. Figure 1 shows the PCDD and PCDF fingerprints of two typical paper samples consisting of chlorine bleached pulp and recycled pulp, respectively. In the recycled pulp sample the chlorine bleaching pattern (TCDDs and TCDFs) is only of minor importance. The higher chlorinated dioxins, especially some HxCDD - e.g. 123679/89-HxCDD (peak No.68/69) - both HpCDD and the OCDD are dominating. Within the furans the higher chlorinated congeners are dominating too but the concentrations are much lower compared to those of the dioxins. Therefore, the fingerprint shown can be regarded as typical for recycled pulp products.

HxCDF

~28/125

HxCD ~F

128/125

I

133

HpCDF

HpCDF

OCDF

Recycled pulp I

~2

TCDD

TCDD

Chlorine bleached pulp

PeCDD

PeCDD

7~/72 1 ,~

r~/s9

HxCDD

HxCDD

~0

HpCDD

HpCDD

OCDD

OCDD

Figure 1: PCDF and PCDD mass fragmentograms (fingerprints) of two typical paper samples consisting of chlorine bleached pulp or recycled pulp Peak numbering according to Ballschmiter et al./12/

i~T ~s7~2 PeCDF

TCDF

PeCDF

t78/79/80/57/62

TCDF

1991

PCDD/F Mass Balances The presentation and detailed discussion of all 150 samples analysed and the corresponding PCDD/F mass balance of each mill would be beyond the scope of this article. Therefore, only the important results are sumrnerized below. In two pilot plants working with new pulping technologies (ASAM- and Organocell process) no or only negligible PCDD/F amounts were detectable. The calculation of a complete PCDD/F mass balance was neither possible nor necessary. The PCDD/F concentrations in the final pulps were close to or below the detection limit of 0.1 ppt I-TE. The samples from the LWC- and SC-paper production showed PCDD/F values too low to determine a detailed PCDD/F mass balance. Usually, the PCDD/F concentrations in the final products ranged between 0.28 and 0.61 ng I-TE/kg with the exception of one LWC-paper (1.25 ppt I-TE). Nevertheless, it could be noticed, that the imported sulphate pulp bleached with chlorinated substances is still the major input of PCDD/Fs in the production process of these papers. PCDD/F values from 0.25 to 1.3 ng I-TE/kg dry weight were measured in the imported pulp samples (Table 2). Table 2: Sources of PCDD/Fs in the paper production

Imported kraft pulp

0.2 - 1.3 ng I-TE/kg dw

(ECF, chlorine dioxide bleached) Waste paper

3 - 10 ng I-TE/kg dw

Stock additives

less than 1 ng I-TE/kg (mainly)

(application mixtures)

7 - 55 ng I-TE/kg (single products)

dw: dry weight ECF: elemental chlorine free bleached The PCDD/F mass balance of a recycling paper mill has already been presented at the 12th International Symposium on Dioxins and Related Compounds DIOXIN 92/13/. In the meantime four additional paper mills producing papers or paperboards from only recycled fiber material were investigated. The results did confirm the earlier findings. The calculated PCDD/F mass balances ranged between 97 and I08%, with the exception of one mill where the quantity of outgoing sludge has been overestimated. Mainly some higher chlorinated dioxins could be determined in samples of the waste paper input as well as in samples of the intermediates and the final products. No differences in the PCDD/F pattern within the whole production process could be observed in any mill. This conftrrned the assumption, that no relevant amounts of PCDD/Fs are formed in the production process or introduced by process chemicals which have not been

1992 analysed. For example, the correspondence of the PCDD/F patterns within the production process of a corrugated paper mill is shown in Figure 2.

m

Wetsten

~SJp6

rl

out Tip

- ' N ~ . , ~ , ~ x ~ , ~ , m , 1 i 1 i i ~ f i

I

i

i

r

~, i

i

I

~ , ¢ x ~ . q : 2 1 ~ ; Z ~ ~ i ~ i i i i i i ~ i

i

z

,an i ~,~

Figure 2: PCDD/F pattern within the corrugated paper production The main PCDD/F-input in the production of recycled fiber products came from the waste paper. The PCDD/F levels in the waste paper samples ranged between 3 and 10 ng I-TE/kg dry weight (Table 2). Therefore the waste paper had a share of 93 up to 100% in the total PCDD/F-input. In some mills a small additional input was caused by sizing agents consisting of tall oil rosin (Table 2). Using a deinking system the PCDD/F concentrations in the recycled pulp products are about three times lower than the concentrations in the corresponding waste paper. Depending on the type of paper PCDD/F concentrations between 1.1 and 7.2 ng I-TE/kg were measured in the final products. It is remarkable, that in general the waste paper showed higher PCDD/F levels than the corresponding newly produced paper of the same type. This has been due to some different contamination sources, e.g. printing inks and pentachlorophenol, coming from previous processing and use /14/. A comparison of the PCDD/F levels between paper web samples after the press section of the paper machine and the corresponding final products showed no differences. This means, that no measurable evaporation of PCDD/Fs could be observed in the dryer section of the paper machine. This investigation allowed us to make an estimation on the formation and occurrence of PCDD/Fs in the German paper production in 1992. No measurable amounts of PCDD/Fs were formed by manufacturing 13 million tons of papers and paperboards. An annual total amount of 0.6 to 3.9 g I-TE was imported with the

1993 chlorine dioxide bleached kraft pulp and the total PCDD/F-input into the paper production from the waste paper ranged between 16 and 50 g I-TE/year in 1992. The input from stock additives was unimportant for this calculation. This total amount of the PCDD/F-input into the paper production from these sources has been in good agreement with another prediction. Using the PCDD/F levels listed in Table 1 and results from other examinations an annual total amount of 27 to 65 g I-TE could be estimated for the occurrence of PCDD/Fs in the paper and paperboard production in Germany in 1992. CONCLUSION No formation of PCDD/Fs has been found in any part of the paper and paperboard manufacturing process. This statement is also valid for the deinking process of waste papers. The main input of PCDD/Fs in the production of papers containing only primary fibers results from the chlorine dioxide bleached kraft pulps. As there is no such kraft pulp produced in Germany all PCDD/Fs in these products are imported. The PCDD/F mass balances for paper mills producing papers and paperboards only out of recycled fibers showed the waste paper as the main input. In comparison with chlorine or chlorine dioxide bleached pulp products, the recycled pulp products showed a different PCDD/F congener pattern. The higher chlorinated dioxins are dominating in these products. ACKNOWLEDGEMENT This study is part of the research project 01 Z 9004 of the Federal Ministry of Research and Technology (BMFT). It was fmancially supported by the Verband Deutscher Papierfabriken (VDP). We would like to thank all participating mills for their great support and we gratefully acknowledge the assistance of Anita Gruner and Albert Bichlmaier. REFERENCES /1/ /2/ /3/

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