Alternative policy assessment for water pollution control in China's pulp and paper industry

Resources, Conservation and Recycling 66 (2012) 15–26

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Alternative policy assessment for water pollution control in China’s pulp and paper industry Chao Zhang, Jining Chen ∗ , Zongguo Wen Division of Environmental System Analysis, School of Environment, Tsinghua University, Beijing 100084, China

a r t i c l e

i n f o

Article history: Received 1 October 2011 Received in revised form 3 May 2012 Accepted 1 June 2012 Keywords: Pulp and paper industry Water pollution reduction Technology-based model Policy assessment

a b s t r a c t The pulp and paper industry is the most important industrial sector for water pollution control in China. The current paper develops a technology-based model to assess alternative water pollution reduction policies in the pulp and paper industry up to 2020. Five policy scenarios are established to represent measures of raw material substitution, eliminating backward small-sized capacities, promoting cleaner technologies, advancing end-of-pipe treatment technologies and the integration of all these policies. Emission amounts of wastewater, chemical oxygen demand (COD), ammonia nitrogen (NH4 -N) and absorbable organic halides (AOX) under different scenarios and corresponding economic costs are calculated. Among all individual policy measures, production capacity replacement has the best pollution reduction effect and the largest capital investment demand. Promoting cleaner technology can bring more economic benefits with less investment because of its by-effects of material and energy saving. Although raw material substitution is a basic strategy in China’s paper industry, it does not show very significant pollution reduction effect on its own. Joint implementation of different policies is necessary in order to decrease gross emission amounts when total output keeps growing. The water pollution emission reduction target proposed in the development plan of China’s paper industry, i.e. 10–12% reduction of COD and NH4 -N in 2015 based on 2010 level, can be fulfilled through integrated policy measures. © 2012 Elsevier B.V. All rights reserved.

1. Introduction Pulp and paper making, a wastewater discharge intensive sector, has long been among the major water polluters in China. In 2009, for example, this sector discharged 18.8%, 28.9%, and 11.2% of national industrial wastewater, COD, and NH4 -N emission loadings, respectively (NBS and MEP, 2010). These values are partially attributable to the fact that paper consumption has been soaring with China’s rapid economic growth over the last decade. Gross consumption of paper and paper board, for example, increased from 35.75 million tons in 2000 to 85.69 million tons in 2009, with an average annual growth rate of 10.2%. In parallel, per capita consumption per year was significantly increased from 28 kg to 64 kg in the same period (CPA, 2009); such a growth is widely projected to continue in the next decade. Thus, the need to formulate a long-term policy for the effective prevention and control of water pollution from the pulp and paper industry must be addressed. Sector-wide water pollution control has been studied in many pulp and paper producing countries (e.g. Junna and Ruonala, 1991; Lagergren and Nystrom, 1991; Kroiss, 1994; Luonsi and Juuti, 2005;

∗ Corresponding author. Tel.: +86 10 62782015; fax: +86 10 62770349. E-mail addresses: [email protected], [email protected] (C. Zhang), [email protected] (J. Chen). 0921-3449/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.resconrec.2012.06.004

Jawjit et al., 2007). These studies covered not only emission trends and control strategies, but effects from process-integrated cleaner production (Gupta, 1994) and technological changes (Malinen et al., 1994; Hailu, 2003) as well based on scenario analysis, modeling tools, and cost and benefit analysis (e.g. Luken et al., 1992; McClelland and Horowitz, 1999). More recently, a greater number of studies highlighted energy consumption and greenhouse gas (GHG) emissions from the pulp and paper sector at global or national levels because of increasing concern on climate change (e.g. Möllersten and Westermark, 2003; Davidsdottir and Ruth, 2004; Kallio et al., 2004; Szabó et al., 2009). In the last two decades, the rapid growth of the pulp and paper industry in China has run parallel to an increasingly strict and comprehensive control of discharged water pollutants. The adopted actions included large-scale closures of small and backward mills, as well as enforced construction of end-of-pipe treatment facilities. To meet long-term water quality objectives, however, China is believed to rely increasingly on the application of innovative technologies. For this purpose, we had developed an optimization model to evaluate the effects of future cleaner technologies on the potential reduction of COD discharge from the pulp manufacturing sector (Zhang et al., 2009). This paper is an extension of our early study. The newly developed model not only covers key cleaner technologies, but likewise considers the effects from changes in material sources, plant scales, and advanced end-of-pipe treatment

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technologies in the entire pulp and paper manufacturing sector. The concerned water pollutants are further extended to include more major ones from the pulp and paper sector, including NH4 -N and AOX. The aim of the current study is to investigate the effectiveness of different integrated control strategies for managing future water pollution from the pulp and paper industry in China. The current study is organized as follows: Section 2 illustrates the technology-based water pollution simulation model, in which a systematic representation of the pulp and paper industrial processes is developed together with descriptions of cleaner technologies and end-of-pipe treatment technologies. Alternative policy scenarios are designed in Section 3; these consider four aspects of policy design, particularly changes in raw material sources, control of plant scales and production processes, cleaner technology diffusion, and level of end-of-pipe treatment. Detailed results and discussions are presented in Section 4 before the paper is concluded.

t t = GA,i,p ·[ EA,i,p



t eop,i · (1 − ϕeop,i,p )]

(2)

eop ∈ SETi (eop)

where EtA,i,p is the emission coefficient of pollutant p from production process i for producing per unit product A in year t; ϕeop,i,p is the removal rate of pollutant p by the end-of-pipe treatment t is the applitechnology eop when applied to process i; and eop,i cation ratio of eop in process i in year t. If pollutants are directly discharged without any end-of-pipe treatment, an “empty technology” with the removal rate of 0% is then assumed. In this manner, the application ratio of all related end-of-pipe technologies for each production process should add up to 100%:



t eop,i = 100%

(3)

eop ∈ SETi (eop)

2. Methodology

Finally, total emission load is derived by summing up the emission loads of all production processes as follows:

2.1. Technology-based methodological framework A technology-based simulation model is a common approach for projecting future industrial production and their associated environmental performance. This method can be a flexible and useful tool for policy evaluation when combined with scenario analysis. Typical examples are the Long-range Energy Alternatives Planning (LEAP) System developed by the Stockholm Environment Institute (SEI) (SEI, 2006; Wang et al., 2007; Cai et al., 2008) and the Model for Analysis of Energy Demand (MAED) (Hainoun et al., 2006; Yuksek et al., 2006). However, both models focus only on the energy system, relevant air pollution, and GHG emission by describing details from energy production and distribution to end-use sectors. Applying the technology-based simulation approach, our model herein focuses on water pollution emission at sector level, based on a detailed conceptual description of industry production system. This model has been applied to assess the water pollution reduction and energy saving potential in China’s synthetic ammonia industry (Zhang et al., 2012) by the authors. In this section, we briefly introduce the main formulas of the model. As shown in Fig. 1, the entire sector is categorized into a number of production processes with different plant sizes. Each production process may utilize different raw materials and produce different products. In addition, each production process is associated with different process-integrated pollution prevention technologies (or cleaner technologies) and end-of-pipe treatment technologies. The developed model could thus present a full evaluation of different pollution control policies from structural changes (i.e. changes in production process, plant size, raw material source and products) to technological advancement. Total pollution emissions from the entire pulp and paper sector are simulated on a yearly basis. First, the pollution generation coefficient of each production process is calculated based on the diffusion of cleaner technologies, as shown in Eq. (1): t+1 t = GA,i,p · GA,i,p

To account for pollution reduction from the end-of-pipe treatment technologies, the pollution emission coefficient is thus calculated as given in Eq. (2).



t+1 t [1 − ct,i,p · (ˇct,i − ˇct,i )]

(1)

ct ∈ SETi (ct)

where GtA,i,p is the generation coefficient of pollutant p from the production process i for producing per unit product A in year t; ct,i,p is the reduction rate of pollutant p when cleaner technology ct is t is the diffusion rate of cleaner technolapplied to process i; and ˇct,i ogy ct applied in production process i in year t. The dynamic change in pollution emission coefficients thus relies on the diffusion of cleaner technologies.

TEpt =

 

t t DA,i · EA,i,p

(4)

A i ∈ SETA (i)

where TEtp is the total emission load of pollutant p in year t; and DtA,i is the total output of product A by process i in year t. 2.2. Structure of China’s paper sector Figs. 2 and 3 show the process structures of China’s pulp and paper manufacturing system, respectively. The aggregation level was selected with consideration to data availability. The pulping system is rather complex, with nine kinds of raw materials, 31 production processes, and five products; the total number of possible combinations of raw materials, production processes, and products is 59. In the raw material aspect, three major kinds of fiber resources are considered, namely, non-wood fibers, wood fibers, and recycled paper. Non-wood fibers are further divided into straw, reed, bagasse, and bamboo. Other non-wood materials, such as kenaf stalk, cotton or cotton stalk, and rag with very small proportions, are not considered in the proposed model. Wood fibers are simply divided into soft and hard wood. Recycled paper is divided into mixed office waste (MOW), old newsprint (ONP), and old corrugated container (OCC). Pulp species are classified based on the adopted production processes, such as chemical pulping, semi-chemical pulping, chemi-mechanical pulping, and mechanical pulping. Production processes are further divided into different plant sizes. The simulated paper manufacturing system includes 17 production processes and six final products, namely, newsprint, household paper, printing and writing paper, wrapping paper, paper board, and corrugated paper. Different plant sizes are also distinguished in the paper manufacturing system. 2.3. Key cleaner production technologies China’s pulp and paper industry has undergone a great deal of technology progress in the last two decades. Advanced technologies and equipment have been developed and applied for cooking, washing and screening, bleaching, chemical recovery, and papermaking, with significant reduction in pollution emission and resource consumption (Yang, 2003; Huang, 2003; Cao, 2009). Based on an intensive literature review and on-site survey, 14 cleaner technologies with a high level of importance were identified for their significant water pollution reduction potential. These are as

C. Zhang et al. / Resources, Conservation and Recycling 66 (2012) 15–26

Fig. 1. Conceptual framework for simulating water pollution emission loads in industrial sectors.

Fig. 2. The conceptual structure of China’s pulping system.

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Fig. 3. The conceptual structure of China’s paper manufacturing system.

follows: dry and wet preparation for straw pulping; dry timber debarking; extended delignification cooking; super batch cooking; multi-stage countercurrent pulp washing; closed screening; medium consistency pulping and refining; oxygen delignification; elemental chlorine free bleaching (ECF); total chlorine-free bleaching (TCF); advanced alkali recovery; flotation de-inking for recycled pulp; enzymatic de-inking for recycled pulp; fiber recovery and white water reuse. Most of these technologies were first introduced in China in the 1990s and 2000s. The future diffusion or a full application is widely acknowledged to be of critical importance for decreasing water pollution loads in China’s paper sector. More detailed information on these cleaner technologies is presented in Appendix.

Ma, 2008). In the proposed model, the end-of-pipe treatment technologies are classified into the following four categories: primary treatment, such as filtration, coagulation, sedimentation, and flotation; aerobic biological treatment, such as traditional activated sludge, sequencing batch reactor treatment (SBR), and oxidation ditch; anaerobic–aerobic biological treatment, such as anaerobic/oxic (A/O) process and up-flow anaerobic sludge blanket (UASB) plus aerobic treatment; and tertiary treatment with water reuse, such as additional physical and chemical treatment after secondary biological treatment, and membrane technologies. Removal efficiencies for COD, NH4 -N, and AOX using different technologies, as well as their combinations, were investigated.

2.4. Wastewater treatment technologies

3. Scenario design and data collection

Effluents from paper mills are widely reported to cause serious damage to the receiving environment (Ali and Sreekrishnan, 2001). Detailed reviews could be found in public literature on the characteristics of paper mill effluents and their treatment using different technologies (see Thompson et al., 2001; Polhrel and Viraraghavan, 2004; Buyukkamaci and Koken, 2010). In China, with increasingly strict control on wastewater discharge, secondary treatment has become the norm for newly built pulp and paper mills (Wan and

Generally speaking, consumption of paper products shows close relationships with economic growth (e.g. Chas-Amil and Buongiorno, 2000; Jha and Bhati, 2007; McCarthy and Lei, 2010). The industrialization and urbanization of China in the near future will be strong driving forces for steady increase of paper product output. In this study, the average annual increase rate of total output of paper product is set to be 4.6% during 2011–2015 (NDRC, 2011) and 4.2% during 2016–2020. Total pulp demand is calculated based on a constant pulp to paper ratio of 0.92. Different scenarios shared the same assumption of future demand. According to this assumption, total paper output will be 116.0 million tons in 2015 and 142.6 million tons in 2020, the corresponding total pulp demand will be 106.7 million tons in 2015 and 131.2 million tons in 2020 (see Table 1 for details). Scenario design in this study covers all important policy measures currently known that will make differences to water pollution emissions of China’s pulp and paper industry. A baseline scenario is defined as no policy intervention situation in which structures and pollution emission intensities of all production processes remain unchanged. Therefore, pollution emissions under the baseline scenario are only determined by total output expansion. Four individual policy scenarios are constructed according to different

Table 1 Predicted future pulp and paper demands in China (million tons). Products

2010

2015

2020

Newsprint Household paper Printing and writing paper Wrapping paper Paper board Corrugated paper Other paper Total paper output Total pulp demand

4.3 6.2 22.6 6.0 31.3 18.7 3.6 92.7 84.6

5.4 7.7 28.3 7.5 39.2 23.4 4.5 116.0 106.7

6.6 9.5 34.8 9.2 48.1 28.8 5.5 142.6 131.2

Notes. “Other paper” is not included in our model.

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Table 2 Scenario definitions and relevant policies. No.

Major contents

Relevant policies

Baseline

Structure and emission intensities of pulp and paper industry remain unchanged Raw material substitution through forest-paper integration and promoting domestic waste paper recycling

No policy intervention

Scenario A

Special plan on forest-paper integration construction (NDRC, 2004); Development plan for paper industry in the 12th five year period (2011–2015) (NDRC, 2011)

Scenario B

Shutting down backward small-sized pulp and paper mills, making minimum size requirement for newly built plants

National plans for backward production capacity elimination in the 11th five-year (2006–2010) and 12th five-year (2011–2015) period (State Council, 2007, 2011); Market access conditions for paper industry (NDRC, 2007)

Scenario C

Promoting cleaner production technologies in both new and existing plants

Cleaner production standards in pulp and paper industry (MEP, 2006, 2007a, 2007b, 2009); Development plan for paper industry in the 12th five year period (2011–2015) (NDRC, 2011); Several technology guidelines for energy saving and pollution reduction in paper industry (MIIT, 2010; SAES and BJFU, 2010; CNLIC and CNPPRI, 2012)

Scenario D

Strengthening effluent discharge limitations and promoting tertiary treatment of wastewater

The revised effluent limitations for pulp and paper industry (MEP, 2008a)

Scenario E

Policy integration

All measures listed in scenario A, B, C and D

Table 3 Raw material structure change in Scenario A (%). Pulp type Imported wood pulp Domestically produced pulp

Non-wood pulp

Wood pulp Reclaimed pulp Other pulp Sum

Straw pulp Reed pulp Bagasse pulp Bamboo pulp

2010

2015

2020

13.6

14.0

12.0

8.5 1.8 1.4 2.3 8.4 62.7 1.3

5.7 1.5 1.1 2.3 10.3 64.0 1.1

4.5 1.2 0.9 2.4 12.0 66.0 1.0

100

100

100

Notes. Emissions from “Other pulp” are not included in our model.

pollution reduction policies, i.e. raw material substitution, phasing out backward capacities, promoting cleaner production technologies and strengthening effluent limitations. The effect of each individual policy scenario at the absence of other measures is simulated by the model. Finally, an integrated scenario with all policy measures is defined to explore the best environmental performance that can be achieved. Relevant policies on which these scenarios are based are listed in Table 2. Forest-paper integration is an important policy to adjust raw material structure in China’s paper industry (Suo, 2009). In 2004, a national plan has been drafted to set the target and measures for implementing forest-paper integration project in China (NDRC, 2004). The outputs of domestic wood pulp and bamboo pulp have been expected to reach 7.5 million tons and 1.6 million tons in 2010 respectively. According to the plan, total capacities of wood pulp and bamboo pulp will reach 13.65 million tons and 3.95 million tons respectively after all scheduled projects have been constructed. The newly issued development plan for paper industry (NDRC, 2011) also proposed a target of raw material structure to be achieved in 2015. Raw material structure in scenario A is set according to these plans as shown in Table 3. In scenario B, China’s strict policy of eliminating outdated smallsized production capacities is represented by the change of plant size structure. In 2006–2010 (the 11th five-year planning period in China) about 10 million tons of pulp and paper production capacities have been shut down (Li, 2010) This number largely exceeded the expected target of 6.5 million tons originally set by the State Council (2007). New closure plan for outdated production capacity in 2011–2015 has been issued recently (NDRC, 2011). It has been

specified that chemical wood pulp lines below 51 kt/yr, non-wood pulp lines below 34 kt/yr and recycled fiber-based pulp lines below 10 kt/yr must be shut down. In addition to outdated capacity elimination, newly built facilities and expansion of existed mills should also meet minimum scale requirements. These measures will accelerate capacity replacement and increase the average size of pulp and paper mills in China. Promoting the application of cleaner technologies is represented by Scenario C (see Table 4 for details). Current penetration rates of selected key cleaner technologies are investigated through industry surveys, literature review. Future penetration rates are set mainly according to the expectations in some technology guidelines for cleaner production and energy saving (MIIT, 2010; CNLIC and CNPPRI, 2012) as well as to experts’ opinions and the authors’ judgment.1 In addition to the promotion of processintegrated cleaner technologies, end-of-pipe effluent treatment plays an essential role in emission control. Scenario D reflects the changes in wastewater treatment technologies driven by stricter discharge limitations. The overall application rate of tertiary treatment technologies is set to be 20% in 2015 and 35% in 2020.

1 Some other information can also help us to estimate possible penetration levels of certain cleaner technologies. For example, traditional elemental chlorine bleaching technology has been forbidden in newly built capacities in China. Therefore, the penetration rate of ECF and TCF technology will gradually increase with capacity expansion in the future. Penetration rate of these two environmental friendly technologies will add up to about 50% in total domestic virgin pulp in 2020, even there will be no technology replacement in existing capacities. So the technology promotion targets in Scenario C could be set higher than this basic level.

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Table 4 Technology penetration rates set in Scenario C (%). Technology

Applicable scope

Penetration rate

Dry and wet feedstock preparation and horizontal continuous cooking Dry timber debarking Extended delignification cooking Low energy batch cooking Multi-stage countercurrent pulp washing Closed screening Oxygen delignification before bleaching Elemental chlorine free bleaching (ECF) Total chlorine free bleaching (TCF) Advanced alkali recovery Medium consistency refining Flotation deinking for recycled pulp Enzymatic deinking for recycled pulp High efficiency white water reuse and fiber recovery

Non wood chemical pulp Wood pulp Wood chemical pulp Wood chemical pulp All virgin chemical pulp All virgin chemical pulp Wood chemical pulp All virgin chemical pulp All virgin chemical pulp Soda (non-wood) and sulfate (wood) pulp Recycled pulp Recycled deinking pulp Recycled deinking pulp All paper making processes

2010

2015

2020

40 55 10 15 45 30 50 15 2 30 20 40 2 20

70 75 25 25 70 60 80 45 5 60 40 75 8 40

85 90 45 35 90 90 90 65 10 85 65 90 20 70

Notes. Technology penetration rates are defined base on their corresponding applicable scopes.

Furthermore, the combined effects of all individual policy measures are simulated through Scenario E, which represents the most optimistic technological advancement expectation and best environmental performances that can be achieved. Data for this study were available from diverse sources. Pollution generation coefficients of different production processes in 2008 and removal rates of alternative wastewater treatment technologies come from China’s industry pollution generation and emission coefficient manuals (MEP, 2008b). Pollution reduction effects and cost information of cleaner production technologies were collected from cleaner production standards, technology guidelines mentioned above and application cases reported in a variety of literatures. The consistency of all information has been checked and assured through a technology database developed in this study. 4. Results analysis 4.1. Emission trends under alternative policy scenarios Simulation results for water pollution emission trends of all scenarios are shown in Fig. 4. Emissions from 2008 to 2010 are calculated based on historical statistics. In 2010, the simulated total emission amounts of wastewater, COD, NH4 -N and AOX are 4.06 billion tons, 1.04 million tons, 22.2 kt and 14.3 kt respectively. Emissions under the baseline scenario will increase by 25.7% in 2015 and 54.5% in 2020 compared with 2010. These amounts could be regarded as the upper extreme of water pollution emissions in the pulp and paper industry. It is clear that the gross emissions of all pollutants will keep increasing under any individual policy scenario (Scenario A to D), except for AOX emission under Scenario C. Production capacity replacement by shutting down small-sized plants, as represented by Scenario B, shows better effects on wastewater, COD and NH4 N reduction than other measures. Compared with the baseline

situation, this measure can reduce total wastewater, COD and NH4 -N discharge by 20.7%, 31.5% and 20.1% respectively in 2020. However, if compared with the emission level in 2010, these amounts will still increase by 22.6%, 6.0% and 23.5% respectively. Raw material structure adjustment through forest-paper integration policy and more efficient paper recycling (Scenario A) does not show significant pollution reduction effect on its own. Although wood pulp and recycled pulp both have relatively lower emission intensities per unit product than traditional non-wood pulp, such environmental benefits will partially be offset by their increasing domestic output. Promotion of process integrated cleaner technologies (Scenario C) has almost as good effects as Scenario B on wastewater and NH4 -N reduction. However, the COD control effect of promoting end-of-pipe treatment technologies (Scenario D) is better than process integrated measures. Whether to prevent pollution generation or eliminate them after generation is a common problem of technology choice. Our calculation shows that these two approaches will make big differences in economic costs, on which we further discuss in Section 4.5. AOX emissions show different pattern from other pollutants. The promotion of environmental friendly ECF and TCF bleaching technology included in Scenario C is a key factor for AOX emission control. Total discharge amount of AOX in 2020 can be reduced by 47.8% compared with the baseline situation, or by 19.0% compared with the emission level in 2010. All other three individual policy scenarios have relatively close effects on AOX reduction. The combination of all these policies, represented by Scenario E, can achieve considerably good effect on gross emission control. In 2015, total amount of wastewater, COD, NH4 -N and AOX can be reduced by 6.2%, 24.7%, 13.5% and 37.9% respectively compared with 2010, and in 2020, these reduction effects increase to 15.3%, 40.0%, 24.8% and 63.6% respectively. Implementing comprehensive measures is necessary for environmental protection in China’s pulp and paper industry, and is also very much likely to take place in the future according to current development plans and regulations

Table 5 Cumulative investment under different scenarios (109 yuan). Scenario

Baseline Scenario A Scenario B Scenario C Scenario D Scenario E

Total investment

Investment for wastewater treatment

2011–2015

2016–2020

Sum

2011–2015

2016–2020

Sum

70.1 69.9 94.7 74.4 73.4 91.0

78.4 81.6 115.5 84.0 85.5 124.2

148.5 151.5 210.2 158.4 158.9 220.2

7.3 6.2 9.5 6.8 10.7 9.2

8.1 7.3 10.5 6.7 15.2 11.6

15.4 13.6 20.0 13.5 25.9 20.8

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Fig. 4. Pollution emission trends under different scenarios.

abovementioned. Therefore, we make more detailed analysis on different aspects of Scenario E in Sections 4.2–4.4.

4.2. Changes in the emission structure Contributions of different pulp and paper products to total emissions in 2010 and 2020 under Scenario E are shown in Fig. 5. The most noteworthy change is the decreasing share of non-wood pulp, especially straw pulp, and the corresponding increasing share of wood pulp. The contribution of straw pulp to total COD emission declines from 21.3% in 2010 to only 8.6% in 2020. Its shares in total wastewater and NH4 -N discharge are also reduced by approximately half. AOX emission structure does not have big changes. As the largest source of AOX emission, straw pulp contributes more than 40% to total AOX discharge in 2020, even its share in domestically produced pulp declines to 5.1%. Emission structure changes are mainly determined by two factors, one is changes in pulp structure and the other is different pollution reduction potentials of different pulp species. The calculation results reflect larger reduction potentials in non-wood pulp than wood pulp.

removal through end-of-pipe wastewater treatment. Decomposition analysis under Scenario E is presented in Fig. 6. Integrated policy measures can cut pollution generation amounts to large extent. Total volume of wastewater generation can be reduced by 22.4% in 2015 and 38.1% in 2020 compared with the baseline scenario. Structure adjustment and technology advancement can also prevent the generation amounts of COD and NH4 -N from sharply increasing while total output keep growing in the future. It is found that structure changes in production capacities can make more contributions to pollution prevention on wastewater, COD and NH4 -N than the selected cleaner technologies, particularly in the short-term, i.e. before 2015. Total generation amount of AOX can be much more significantly reduced than other pollutants. About 65% of AOX reduction effect is attributed to the application of cleaner technologies such as ECF and TCF bleaching. The overall removal rate of pollutants will also be enhanced due to the diffusion of more advanced wastewater treatment technologies. In 2020, the simulated overall removal rates of COD, NH4 -N and AOX will reach 90.4%, 64.1% and 74.2% respectively, compared with 82.2%, 51.9% and 65.4% in 2010.

4.3. Decomposition of reduction effects

4.4. Changes in emission intensities per unit paper product

The technology system in pulp and paper industry is established through coupling relationships between alternative production processes and pollution reduction technologies, both processintegrated and end-of-pipe, attached to each production process. Such model design provides convenience to decompose pollution reduction effects that can be attributed to different factors, i.e. changes in the structure of production capacities, pollution prevention by the promotion of cleaner technologies and pollution

As shown in Fig. 7, the average pollution emission intensities per unit paper product under Scenario E are calculated by dividing total emissions by total paper output. In 2010, emission intensities of wastewater, COD, NH4 -N and AOX are 45.6 t/t, 11.7 kg/t, 0.25 kg/t and 0.16 kg/t respectively. AOX emission intensity has the biggest reduction potential which can be cut by half in 2015 and by 76% in 2020. COD intensity will decrease to 4.6 kg/t in 2020 which is equivalent to 61% reduction. Reduction rate of NH4 -N intensity is

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Fig. 5. Changes of emission structure under Scenario E.

Fig. 6. Decomposition of pollution reductions under Scenario E.

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Fig. 7. Changes of emission intensities per unit paper product under Scenario E.

about 10% smaller than that of COD. Major water pollutants show quite large reduction potentials in China’s pulp and paper industry. 4.5. Cost estimation In this section, computation results of economic costs of alternative policy scenarios are presented. Details of cumulative capital investments are listed in Table 5. Investment is composed of two parts in the model, i.e. (1) investment for production equipments including additional investment needed for cleaner production technologies, and (2) investment for wastewater treatment facilities. Production capacity replacement (Scenario B) needs much more capital investment than other individual policies, because more new large-sized capacities will be built to substitute those backward mills. Total capital investment under Scenario B adds up to 210.2 billion yuan, which is 1.42 times than the baseline scenario. Promoting cleaner technologies and strengthening discharge limitations have almost the same total investments. However, process-integrated pollution prevention measures in Scenario C can release the burden on end-of-pipe treatment. So that the investment for wastewater treatment facilities will decrease and only account for 8.5% in total investment. In Scenario D, pollution control efforts are focused on wastewater treatment only, which lead to a comparatively high demand for the construction of effluent treatment plants. Our computation shows that promoting process-integrated cleaner technologies has obvious advantages in terms of economic benefit (see Fig. 8 for the comparison of total production costs and Fig. 9 for wastewater treatment expenditures under different scenarios). These benefits come from energy, water and material saving effects as well as less pollution treatment expenditures. It

Fig. 8. Changes of total production costs compared with the baseline situation.

Fig. 9. Comparison of wastewater treatment expenditures.

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Table A1 Summary of the identified cleaner technologies. Technologies

Application scope

Effects on pollution prevention

Impacts on other production processes

Dry and wet feedstock preparation and horizontal continuous cooking

Suitable for the preparation of non-wood materials, i.e. straw, reed, bagasse, in chemical pulping processes. It can substitute traditional dry preparation and batch cooking technology and is often applied in medium and large sizes of non-wood chemical pulp mill.

Improve raw material quality and increase black liquor abstraction rate in the washing stage by 3–5%, which lead to a reduction of overall COD load.

Both cooking and bleach chemicals can be reduced by 5–12%. It is often applied by combining with horizontal continuous cooking in new non-wood chemical pulping mills.

Dry timber debarking

Suitable for timber preparation and substitute conventional wet debarking technology.

Barks with higher dryness could feed the boiler, thus increase energy efficiency.

Extended delignification cooking

Suitable for wood cooking. Suitable for large mills and economic scale should be at least 100 kt/y. Suitable for wood and bamboo cooking as an update for traditional batch cooking technology. Suitable for straw, reed and bagasse pulp washing. Currently applied in almost all new mills.

Reduce wastewater discharge from 3–10 t/t to 0.5–2.5 t/t. Reduce COD load in the preparation stage from 5–15 kg/t to 1–2.5 kg/t. Reduce Kappa number by 10–14 for soft wood and 2–6 for hard wood. Reduce COD load in bleaching stage by 15–40%. Reduce COD load in bleaching stage by 10–25%.

Low energy batch cooking

Multi-stage countercurrent pulp washing

Closed screening

Suitable for all kinds of pulp washing. Often combined with multi-stage countercurrent washing system.

Medium consistency pulping and medium consistency refining

Suitable for chemical pulp as well as recycled pulp mills and paper mills. Developed in late 1990s.

Oxygen delignification before bleaching

Suitable for all kinds of bleached chemical pulping mills. Widely applied in wood pulping mills, but application in non-wood pulping mills is still limited. Suitable for all kinds of bleached chemical pulping mills.

Elemental chlorine free bleaching (ECF)

Taking straw pulp as an example, black liquor abstraction rate increases from 80–84% to 88%. If further combined with closed screening system, the abstraction rate is expected to be 90–92%. Reduce wastewater discharge from 50–100 t/t to 0–8 t/t, almost no wastewater discharge in brown pulp washing and screening stage. Reduce COD load by 20–30%. Increasing operation consistency from 1–6% to 8–15% in washing, screening, bleaching, pumping and refining stage. Reduce wastewater discharge by 25–35%. Remove 40–60% lignin in brown pulp. Reduce wastewater amount by 20–25%, COD load by 40–55% and AOX load by 30–50% in bleaching stage.

Reduce bleaching chemicals by 10–20%. Reduce bleaching chemicals by 5–15%.

Reduce bleaching chemicals by 40–50% due to the delignification effect before bleaching.

Reduce wastewater amount by 25–35%, AOX load by 70–90% and COD load by 30–60%.

Often combined with Oxygen delignification before bleaching.

Total chlorine free bleaching (TCF)

Suitable for wood and bamboo pulping, application in non-wood pulping is still under development.

Reduce wastewater amount by 65–80% and COD load by 70–90%, no AOX emission. Key technology for dioxin prevention.

Often combined with extended delignification cooking and oxygen delignification before bleaching. Pulp strength and brightness decrease as an expense of good environmental performance.

Advanced alkali recovery

Suitable for sulfate pulping, soda and soda anthraquinone pulping for all wood and non-wood materials. Plant size is a key factor that determines its application. Larger plant size would lead to a better performance and lower recovery cost. Suitable for waste paper mills with deinking process as a substitute for or addition to washing deinking.

Compared with traditional alkali recovery technology, the recovery rate can be increased by 5–8% which lead to significant reduction of COD load in the black liquor of chemical pulping.

Reduce consumption of cooking chemicals due to higher recovery rate.

Reduce COD load from 60–90 kg/t to 50–70 kg/t and wastewater amount by 70–85%.

Paper brightness will be decreased to some extent. But if combining flotation deinking and washing deinking, brightness loss can be prevented.

Enzymatic deinking for recycled pulp

Suitable for waste paper mills with deinking process.

Get better deinking effect and improve pulp quality.

Fiber recovery and white water reuse

Suitable for all kinds of paper mills. Currently, white water reuse varies considerably from more than 80% in advanced paper mills to almost no reuse in poorly operated mills.

Use enzyme to substitute 50% deinking chemicals can reduce COD load by 22–28%, substitute 70% chemicals can reduce COD load by 45–50%. Significantly reduce wastewater discharge, reduce COD load by 15–40%.

Flotation deinking for recycled pulp

is estimated that 5.1 billion yuan (approximately 1.5% of total production cost) can be saved under Scenario C in 2015 compared with the baseline scenario, and such benefit will increase to 12.8 billion yuan (approximately 3.0% of total production cost) in 2020. On

Increase paper production by 0–2% due to fiber recovery.

the other hand, raw material substitution policy (Scenario A) will largely increase production cost, because wood materials are more expensive than other non-wood materials used as pulping feedstock. The additional cost is estimated to be 8.5 billion yuan in 2015

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and 27.3 billion yuan in 2020, which is equivalent to about 2.5% and 6.4% of the corresponding total production cost in the baseline scenario respectively. Both Scenario B and Scenario D result in only small increases of total production cost. For Scenario D, the increasing production cost is contributed by its much larger wastewater treatment expenditures than any other scenarios. When these individual policy measures are combined together (Scenario E), the economic benefits from cleaner technology application can offset a small proportion of the additional cost incurred by other measures. 5. Discussions Water pollution reduction in China’s pulp and paper industry has long been a highlighted issue for both industrial and environmental policies. This problem appears to become increasingly important because China has prioritized environmental protection. In the current paper, a bottom-up technology-based model of China’s pulp and paper industry was established. Four individual policy scenarios covering different measures and regulations which have big influences on future development of the pulp and paper industry were designed, i.e. raw material substitution through forest-paper integration and higher waste paper recycling rate, eliminating small-sized backward capacities, promoting cleaner technologies and strengthening discharge limitations. A policy combination scenario representing most strict pollution control efforts was also developed to investigate the water pollution reduction potentials. Effects on wastewater, COD, NH4 -N, and AOX emission reductions up to 2020 and the corresponding economic costs of alternative scenarios were calculated. Capacity substitution through closing small pulp and paper mills and constructing more advanced large plants is quite effective to reduce major water pollutants, e.g. COD and NH4 -N. In China’s 12th five year (2011–2015) development plan for environmental protection, gross emission control targets on COD and NH4 -N have been set as national priorities. Such measures are essential for realizing China’s environmental protection target. Nevertheless, high level of investment demand could be an obstacle to further implement the capacity replacement policy. There should be a balance between environmental benefit and investment cost when implementing the capacity replacement policy. Accelerating the diffusion of cleaner technologies is a choice with better economic efficiency. In order to speed up the application of cleaner technologies, not only technological standards for newly constructed capacities but also extensive retrofit and upgrade in existing plants are needed. Economic benefits from material and energy saving and less wastewater treatment expenditure can guarantee short payback times for these technology investments. In addition, applying environmental friendly bleaching technologies as a measure of source control is very important for toxic AOX emission reduction. Forest-paper integration has been identified as a long-term development strategy in China’s paper industry. If not combined with other measures, its water pollution reduction effect is quite limited. Because the increasing output of domestic wood pulp substituting imported pulp could be new pollution sources. However, it is still crucially important to insist on this basic development policy due to its manifold benefits, e.g. improving self-sufficiency of raw materials, improving product quality and comprehensive competitiveness of the entire sector. Our study revealed that raw material adjustment should be integrated with other measures in order to gain more environmental benefits. Taking all proposed policy measures into consideration, the water pollution reduction potential in pulp and paper industry is large. In the development plan of China’s paper industry, a target of 10–12% COD and NH4 -N emission reduction in 2015 based on 2010 level has been proposed. The computation results in this research

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show that this environmental target can be surely fulfilled by joint efforts of capacity replacement, process-integrated prevention and end-of-pipe pollution removal. The methodology framework established in this paper provides a transparent and convenient approach to account environmental impacts of different industry development trends and to simulate effects and efficiencies of alternative technical and environmental policies. As the current paper mainly focuses on water pollution problem, extensions can be further made to cover more comprehensive resource, energy and environmental issues in China’s pulp and paper industry. Acknowledgments The authors gratefully acknowledge Ministry of Industry and Information Technology (MIIT) of the People’s Republic of China for supporting this work under the project 2009BAC65B00, assessment of energy conservation and pollution reduction technologies in key industries, and Ministry of Environmental Protection (MEP) of the People’s Republic of China for providing technological materials of China’s paper industry. Appendix A. Details of key cleaner production technologies Table A1 briefly summarizes the application scope and effects of selected cleaner technologies in this paper. References Ali M, Sreekrishnan TR. Aquatic toxicity from pulp and paper mill effluents: a review. Advances in Environmental Research 2001;5:175–96. Buyukkamaci N, Koken E. Economic evaluation of alternative wastewater treatment plant options for pulp and paper industry. Science of the Total Environment 2010;408:6070–8. Cai W, Wang C, Chen J, Zhang Y, Lu X. Comparison of CO2 emission scenarios and mitigation opportunities in China’s five sectors in 2020. Energy Policy 2008;36:1181–94. Cao P. A sixty years’ review of new China paper industry and its prospect. China Pulp and Paper Industry 2009;30:6–19 (in Chinese). Chas-Amil ML, Buongiorno J. The demand for paper and paperboard: econometric models for the European Union. Applied Economics 2000;32:987–99. CB CNLIC (China National Light Industry Council), CNPPRI (China National Pulp and Paper Research Institute). Technology guide for energy saving and pollution reduction in paper industry. Beijing; 2012. CPA (China Paper Association). Annual report of China’s paper industry in 2009; 2010. Davidsdottir B, Ruth M. Capital Vintage and climate change policies: the case of US pulp and paper. Environmental Science and Policy 2004;7:221–33. Gupta PK. Environmental management in the agro-based pulp and paper industry in India: a holistic approach. Water Science and Technology 1994;30:209–15. Hailu A. Pollution abatement and productivity performance of regional Canadian pulp and paper industries. Journal of Forest Economics 2003;9:5–25. Hainoun A, Seif-Eldin MK, Almoustafa S. Analysis of the Syrian long-term energy and electricity demand projection using the end-use methodology. Energy Policy 2006;34:1958–70. Huang R. A comprehensive view of the trend of development of China’s paper industry technological progress. China Pulp and Paper Industry 2003;24:19–21. Jawjit W, Kroeze C, Soontaranun W, Hordijk L. Options to reduce the environmental impact by Kraft pulp industry in Thailand: model description. Journal of Cleaner Production 2007;15:1827–39. Jha R, Bhati UN. Economic determinants of newsprint consumption in India: a time series analysis, ; 2007 [accessed 11.11.10]. Junna J, Ruonala S. Trends in water pollution control in the Finnish pulp and paper industry. Water Science and Technology 1991;24:1–10. Kallio M, Moiseyev I, Solberg B. The global forest sector model EFI-GTM: the model structure. European Forest Institute; 2004, Internal report no. 15 [accessed 14.03.11] http://northerntosia.org/files/attachments/publications/ir 15.pdf. Kroiss H. Water protection in the pulp industry: Austrian and central-European situation. Water Science and Technology 1994;29:33–48. Lagergren S, Nystrom E. Trends in pollution control in the Swedish pulp and paper industry. Water Science and Technology 1991;24:11–7. Li YZ. Outdated production capacity elimination targets have been fully achieved in the 11th five-year planning period (2010-5-28), ; 2010 [accessed 10.04.12].

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