Cleaner production: a case study of Kaveh paper mill

Abstract

The pulp and paper industry is under increasing pressure to reduce its energy consumption and impact on the environment. The ‘Cleaner Production’ (CP) approach has been widely utilised as a tool to meet environmental concerns by industry. However, because of the high initial capital cost of CP implementation, it is important to develop a model for prioritisation. In this paper, using analytic hierarchy process methodology, a tree-level hierarchy model was structured to facilitate the prioritisation process in the Kaveh Papermaking Company located in Iran. Using a literature review and field study, the proposed model can provide a framework for CP implementation in a paper factory. The results show that process change gives higher priority between 5 criteria and that repair of all leaks in the paper-making process gives higher priority between 35 sub-criteria. Process change was further evaluated and discussed in which input material changes gained higher priority. The results of this research can be used to accelerate the implementation of CP in Iran's pulp and paper industry.

Keywords:

• analytic hierarchy process
• cleaner production
• paper mill

1. Introduction

Industrial production without adequate treatment for environmental impacts has led to an increase in water and air pollution, soil degradation and large-scale global impacts such as acid rain, global warming and ozone depletion. To create more sustainable means of production, there must be a shift in attitudes towards proactive waste management practices moving from control towards prevention. A preventive approach must be applied in all industrial sectors. Used in concert with other elements of sound environmental management, cleaner production (CP) is a practical method for protecting human and environmental health and supporting the goal of sustainability (Avsar and Demirer 2006). CP refers to product development that decreases waste generation providing a reduced environmental impact throughout the product's life cycle (Dunn and Bush 2001). It is the continuous application of an integrated preventative environmental strategy to processes, products and services so as to increase the efficiency and reduce the risks to humans and environment (Fresner 1998). The CP approaches that can be applied include recycling, process modification, plant operation improvement and input substitution. CP can be obtained by redesigning products, modifying production processes and changing the chemicals used to less hazardous ones (Ghazinoory 2005). The successful implementation of CP needs not only external support and incentives of finance, policy and the marketplace, but also internal cooperation between the managerial, technical and operating staff of industrial enterprises (Shi 2003). There have been several methods that were suggested for CP introduction and implementation (Tseng et al. 2006, 2007, Lin et al. 2007).

CP implementation in Iran's industrial section in Iran is receiving considerable attention due to high-energy consumption, technical backwardness, lack of competitiveness, the increased role of small and medium-sized enterprises (SMEs) and the many critical environmental conditions in some regions and industries. Ghazinoory and Huisingh (2006) summarised the barriers faced by SMEs when trying to implement CP schemes and emphasised the lack of professional management, poor record keeping, resistance by decision makers, limited technical capabilities and access to technical information, unstable finances and high cost combined with limited low availability of capital for CP in Iran. Shi et al. (2008) indicated that high initial capital cost is one of the most prominent barriers to the implementation of CP in Chinese SMEs.

Historically, the pulp and paper industry has been considered to be a major consumer of natural resources (raw material and water) and energy (fossil fuel and electricity), and a significant contributor of pollution discharges to the environment (Thompson et al. 2001). Ghorbannezhad and Azizi (2009) suggested that CP is a practical method for developing product and decreasing the waste generation, thus reducing environmental impact throughout the product's life cycle. The authors reported that process change is the most prominent CP criterion for Iran's paper-making mills. This situation is more critical for Iran's pulp and paper industry with more than 10 major manufacturers of pulp and paper products and an increasing number of SME production plants that lack the technical capabilities to meet the process standards for minimising raw materials, water and energy consumption. Among the medium-sized paperboard production plants in Iran, the Kaveh company produces 120 tonnes/day of paperboard (testliner) by recycling mixed waste paper and paperboard including old newsprint and old corrugated containers. The Kaveh paper industry is highly water intensive with an average consumption of 11.5 m³ of freshwater/tonne of paperboard and also 2.5 kg of steam/kg of evaporated water for steam consumption in dryer drainage. This compares badly with the standard of water consumption in the paperboard industry which is 4–7 m³ of freshwater/tonne of paperboard and average steam consumption in the dryer of 1.1–1.3 kg of steam/kg of evaporated water (William 1996, Gullichen and Paulapuro 1999).

In order to promote CP awareness by the paper-making sector and reduce the high initial costs for implementation of CP, the analytic hierarchy process (AHP) method was used for the research reported in this paper to prioritise and select the best CP element choices for the Kaveh mill.

2. Methodology

The AHP was first introduced by Thomas Saaty in the 1970s and since then it has been used in many areas including finance, marketing, energy resource planning, sociology and architecture. It can be defined as a multi-criteria decision-making approach which compares all defined measures in pairs and calculates their relative importance. Most of the time, the AHP is used in the choice phase of decision-making (Saaty 2001). Afterwards, other techniques such as linear programming, queuing and multiple objective decision-making are used to solve the problem. In fact, the aim of AHP is to combine quantitative factors to evaluate all the objectives (Saaty 2001). The AHP for decision-making is a theory of relative measurement based on paired comparisons used to derive normalised absolute scales of numbers, whose elements are then used as priorities (Saaty 2007). Metrics of pair-wise comparisons are formed either by providing judgements to estimate dominance using absolute numbers to form the 1–9 fundamental scale of the AHP, or by directly constructing the pair-wise dominance ratio using actual measurements. The AHP can be applied to both tangible and intangible criteria based on the judgements of knowledgeable and expert people, although how to obtain measures for intangibles is its main concern. The weighting and adding synthesis process model applied in the hierarchy structure of the AHP combines multidimensional scales of measurement to a single ‘uni-dimensional’ scale of priority. At the end, it is necessary to fit the entire word experience into a system of priorities (Saaty 2007). To investigate the view of different stakeholders on the evaluation of CP implementation in a paper-making factory, the authors conducted a three-phased study, including: (1) identifying elements (criteria and sub-criteria) and structuring a hierarchy model for prioritisation, (2) constructing the questionnaire and collecting data and (3) determining the normalised weights. Opinions obtained from different stakeholders including academia, enterprises and experts were collected via carefully designed questionnaires and then synthesised and analysed using an AHP software tool. ‘Expert Choice’ was the commercially available AHP tool used in this research.

3. Identifying and structuring a hierarchy model for prioritisation

On the basis of an extensive literature review and examples of CP elements outlined in ‘A Training Resource Package’ published by UNEP (Svenningsen et al. 1998), a number of elements were chosen. In this training package, the three main groups of CP options were categorised as source reduction (subdivided into good maintenance and process change), recycling (subdivided into on-site recovery and reuse and creation of useful byproducts) and product modification. For example, process change included four types of options: change in raw material (subdivided into use of non-toxic, use better selection of raw material, e.g. by applying quality standards), better process control (subdivided into optimisation of cooking, refining at the highest possible consistency and installation of calibration equipment), equipment modification (subdivided into installation of efficient showers, providing broke pulper, using high-pressure fibre saver in centri-cleaner, installation of consistency regulator and using pumps of adequate size) and technology change (subdivided into modification of pulping processes, modification of washing and dewatering, e.g. by using twin-wire belt presses and use of alternatives bleaching processes). Among the elements studied, 35 sub-criteria were identified and grouped into five categories. A tree-level hierarchy was structured to facilitate the prioritisation process (Figure 1). The tree is segmented into three levels: the top level contains the CP elements; the second level contains the five categories and, in the third level, there are 35 sub-criteria in total.

Figure 1 A hierarchy model of CP implementation.

4. Developing the questionnaire and collecting data

The next step in AHP is data collection. This was done through a systematic series of pair-wised comparisons among the specific criteria and sub-criteria. Pair-wised comparisons allow respondents to focus on only two criteria at a time, thereby, translating the complex, multi-criteria prioritising problem into a series of pair-wised assessments. The pair-wised comparison matrices were completed with the aid of 10 experts from industry and academia. The AHP then converts these comparisons to criteria weights using a matrix algebra-based algorithm while also checking for consistency in the results.

5. Determining the normalised weights

With the completion of the pair-wised comparisons, mathematical computations were conducted. The first step in the evaluation was to normalise each matrix by adding the values of each b _xy . So, a matrix (B) can be normalised as follows:

Then, the local weight W _Bi was calculated according to the following formula:

After determining the local weights, the global weights of each criteria and sub-criteria were calculated. To avoid misdirection analysis, affected by interviewees' incompatible judgements, AHP establishes a consistency indicator as the standard judgement, if the values are incompatible. The questionnaires involved in incompatible judgements were usually discussed with the respondents. Only the matrices that passed the consistency test were included in the final analysis.

6. Results and discussion

In order to prevent pollution and save water and energy in recycled paper mills, 5 criteria and 35 sub-criteria were evaluated among which ‘process change’ and ‘repair of all leaks’ reached the highest priorities, respectively. Due to the importance of change and modification of process in recycled-paper manufacturing companies and the significant number of the relevant sub-criteria (18 sub-criteria), the results are discussed separately as follows.

6.1 Prioritisation of criteria and sub-criteria

As shown in Table 1, the A2 – process change category is the most prominent CP criterion with a normalised global weight of 0.302 on the second hierarchy level. The A3 – good maintenance category follows behind with a global weight of 0.249. This result is consistent with the current situation in Iran's pulp and paper industry, especially with the increasing number of SME production plants that lack a proper maintenance programme. The global weights of A5 – manpower, A4 recycling and A1 – product modification are less than half of the total weights. At the third hierarchy level, A2.1 – material change is regarded as the most prominent CP sub-criterion under the A2 – process change with local weight of 0.324. A1.1 – high-yield production of paper is regarded as the most prominent CP sub-criterion under the A1 – product modification with local weight of 0.654. Repair of all leaks, creation of useful byproducts, and engineering and educational technicians are regarded as the most prominent CP sub-criteria in the third level under the good maintenance, recycling and manpower criteria, respectively. By examining the global weight ranking for the 35 sub-criteria (Table 2), A3.1 – repair of all leaks, A5.1 – engineering and educational technician, A3.4 – modification and repair of dryer cylinder, A5.3 – professional and technician in the CP field, A1.1.1 – testline paperboard, A5.2 – experienced workers, A1.2 – produce unbleached instead of bleached paperboard, A3.3 – remove blockage in wire and felt showers, A2.1.1 – using better and standard raw material and A4.2.1 – recycle steam condensed are regarded as the top 10 sub-criteria which have high effect on evaluation for CP implementation in the paperboard mill in Iran. Furthermore, we can also implement CP concepts in paper-making mills in a step-wise manner with lower initial costs, which encourages paper industries and managers to implement CP. Implementing the CP concepts described in this paper led to a variety of alternatives to reduce the impact on Irans' environment. These alternatives have both economic and environmental advantages.

Table 1 Local and global criteria and sub-criteria of all CP elements.

Elements	Local weight	Global weight	Elements	Local weight	Global weight
A1 product modification	0.123	0.123	A2.4 change technology	0.258	0.058
A1.1 product high-yield varieties of paperboard	0.654	0.080	A2.4.1 modify pulping process	0.288	0.022
A1.1.1 testliner paperboard	0.589	0.047	A2.4.2 modifying washing and dewatering, e.g. by using twin-wire belt press	0.274	0.021
A1.1.2 white top line paperboard	0.411	0.033	A2.4.3 use vacuum drum shower	0.190	0.015
A1.2 product unbleached instead of bleached paper	0.346	0.043	A2.4.4 modify Krofta process^a	0.248	0.019
A2 process change	0.302	0.302	A3 good maintenance	0.249	0.249
A2.1 input material change	0.324	0.98	A3.1 repair all leaks	0.468	0.117
A2.1.1 using better and standard raw material	0.410	0.040	A3.2 keep taps closed when not in use	0.103	0.026
A2.1.2 kind of retention aids	0.268	0.026	A3.3 remove blockage in wire and felt showers	0.170	0.042
A2.1.3 kind of process aids	0.195	0.019	A3.4 modification and repair of dryer cylinder	0.258	0.64
A2.1.4 law of input raw material to product line	0.127	0.012	A4 recycling	0.158	0.158
A2.1.4.1 FIFO	0.714	0.009	A4.1 creating useful byproducts	0.555	0.88
A2.1.4.2 LIFO	0.286	0.004	A4.1.1 use waste fibre	0.305	0.027
A2.2 process control	0.228	0.069	A4.1.2 use raw material as fuel in boiler	0.248	0.021
A2.2.1 optimum and proper refining	0.384	0.026	A4.1.3 use rejects of cleaners	0.233	0.020
A2.2.2 refined at the highest possible pulp consistency	0.123	0.009	A4.1.4 use remaining material in Krofta (like sludge…)	0.220	0.019
A2.2.3 install calibrator equipment	0.372	0.026	A4.2 one-site recovery and reuse	0.445	0.070
A2.2.4 control of water pressure in the edge of cutting paper	0.120	0.008	A4.2.1 recycle steam condensed	0.504	0.036
A2.3 equipment modification	0.190	0.058	A4.2.2 recycle fibre in white water	0.250	0.018
A2.3.1 install efficient shower	0.236	0.014	A4.2.3 recycle peak water in Krofta	0.246	0.017
A2.3.2 provide broke pulper	0.146	0.008	A5 manpower	0.168	0.168
A2.3.3 install consistency regulator	0.280	0.016	A5.1 engineering and educational technicians	0.391	0.066
A2.3.4 use pump of adequate	0.180	0.010	A5.2 experienced workers	0.261	0.044
A2.3.5 install pressure gauges for water consumption control	0.157	0.009	A5.3 professional and technician in the CP	0.348	0.058
^a Trade name for dissolved air flotation technology for wastewater treatment and fibre fines recovery.

Table 2 Ranking of global weights of criteria and sub-criteria.

Ranking	Global weight
Criteria
1 A2	0.302
2 A3	0.249
3 A5	0.168
4 A4	0.158
5 A1	0.123
Sub-criteria
1 A3.1	0.117
2 A5.1	0.066
3 A3.4	0.064
4 A5.3	0.058
5 A1.1.1	0.047
6 A5.2	0.044
7 A1.2	0.043
8 A3.3	0.042
9 A2.1.1	0.040
10 A4.2.1	0.036
11 A1.1.2	0.033
12 A4.1.1	0.027
13 A2.1.2	0.026
14 A2.2.1	0.026
15 A2.2.3	0.026
16 A3.2	0.026
17 A2.4.1	0.022
18 A2.4.2	0.021
19 A4.1.2	0.021
20 A4.1.3	0.020
21 A2.1.3	0.019
22 A2.4.4	0.019
23 A4.1.4	0.019
24 A4.2.2	0.018
25 A4.2.3	0.017
26 A2.3.3	0.016
27 A2.4.3	0.015
28 A2.3.1	0.014
29 A2.3.4	0.010
30 A2.1.4.1	0.009
31 A2.2.2	0.009
32 A2.3.5	0.009
33 A2.2.4	0.008
34 A2.3.2	0.008
35 A2.1.4.2	0.004

6.2 Prioritisation of process change criteria

As shown in Table 1, the A2.1 – input material change category is the most prominent process change criterion with a normalised global weight of 0.324 on the second hierarchy level. Paper characteristics mainly depend on the raw material used for pulp production. Paper products are not of high quality if the paper is produced from waste paper of different grades. It is recommended that consideration should be given to a waste paper classification system based on the technology characteristics of the paper involved in order to increase the variety of paper grades. The A2.4 – change technology category follows behind with a global weight of 0.258. The most economical advantages can be obtained through technology changes. This criterion can be achieved in water, energy and fuel saving (Abbasi and Abbasi 2004). The global weights of A2.2 – process control and A2.3 – equipment modification are less than half of the total weights. At the third hierarchy level, A2.1.1 – use better and standard raw material is regarded as the most prominent process change sub-criterion under the A2.1 – input material change with local weight of 0.410. A2.4.1 – modifying pulping processes is regarded as the most prominent process change sub-criterion under A2.4 – change technology with local weight of 0.288. Modification of pulping processes can be effected on mechanical energy required to separate fibres, chemical consumptions and fibre quality.

A2.2.1 – optimum and proper refining is regarded as the most prominent process change sub-criterion under the A2.2 with the local weight of 0.384. Proper refining and ideal consistency of refining is the most important operating variable; low consistencies cause fibre damage from the refiner bars, while very high consistencies cause the refiner to plug. A2.3.3 – install consistency regulator is regarded as the most prominent process change sub-criterion under A2.3. By examining the global weight ranking for the 18 sub-criteria, A2.1.1 – using better and standard raw material, A2.1.2 – kind of retention aids, A2.2.1 – optimum and proper refining, A2.2.3 – install calibration equipment, A2.4.1 – modify pulping processes are regarded as the top five sub-criteria which have high effects on process change implementation in the paperboard mill of Iran. Unsorted waste and recovered papers contain several contaminants including pressure-sensitive adhesives, low-weight extractable polymeric materials such as styrene butadiene rubber, copolymers, polyvinyl acetate, polyvinyl alcohol, etc. (Holbery et al. 2000, Kortmeyer et al. 2004). A careful sorting strategy to reach better and standard raw material will ensure proper prevention of pollution in the process. Additives are materials used to improve the finished paper itself or aid in the process of paper making. Retention aids often are polymers that are added to improve the retention of fines and fillers as well as internal sizing of paper; however, the type and amount of additives are important for process efficiency in the paper-making process.

7. Conclusions

CP concepts have been developed as preventive measures for different industrial sectors, in order to increase eco-efficiency and reduce risks to both human health and the environment. An evaluation of CP implementation using the AHP method showed this approach to be capable of systematically minimising waste, improving overall process efficiency and reducing the initial costs. The Kaveh paper-making mill was selected as the case study for this research. Due to limited technical staff capabilities, poor record keeping and poor access to technical information, the results were checked for consistency and the incompatible responses were judged using field work and face-to-face interviews.

The study indicated that repair of all leaks was the most dominant sub-criterion priority for CP implementation at Kaveh. Moreover, the resulting local weights of objective to criteria have also shown that a majority of attributes ranked higher. Particularly, process change (0.302) and good maintenance (0.248) were the most important criteria (Table 2). This study provides good insights into identifying and prioritising the criteria and sub-criteria for the implementation of CP in the Kaveh mill. The results of this study can be generalised to any paper-making mill in Iran using mixed waste paper as the raw material and producing testliner as the final product, but because of various pulping and paper-making processes and variety of final products, the results should be validated for pulp and paper industry in Iran as a nationally approved discipline. Process change concepts described in this paper led to a variety of options to improve management of paper-making processes and reduce the impact on environment. These options have both economic and environmental advantages. Finally, the necessity for CP implementation in Iran is quite obvious, because the pulp and paper sector is less competitive than those in other Asian countries. It is less competitive in comparison to other similar sectors in Iran and consumes more water and energy. The main problem in Iran is the speed of implementation of CP, which can be increased greatly with a national CP programme and a systematic approach for each industry like AHP.