Life Cycle Assessment in a Textile Process

Transcription

1 Life Cycle Assessment in a Textile Process Amelia Morita, Mauro Ravagnani* Chemical Engineering Department, State University of Maringá Av. Colombo, 5790, Maringá - PR, Brazil. ravag@deq.uem.br The textile industry has a high potential of pollution since the raw material source until the final deposition of the final products. To minimize environmental problems some alternatives like reuse of textile products and process optimization are considered in the literature. According to Banar and Cokaygil (2008), Finnveden, et al. (2009), Gonzáles- Garcia et al. (2010), Life Cycle Assessment (LCA) is an important tool to environmental analysis and it is defined as a compilation and evaluation of the inlets, outlets and potential environmental impacts of a product or a process thorough its life cycle. In the present paper LCA is applied to three different products from the sport socks process production: product 1 has 85 % of cotton (CO), 12 % of polyamide (PA) and 2% of elastane (PU); product 2 has 70 % of CO, 27 % of PA and 3 % of PU and product 3 has 66 % of CO, 32 % of PA and 2% of PU. The main objective is to find the environmental impacts in four categories: ecotoxicity, climate change, acidification/eutrophication and fossil fuels. Simapro TM was used and the results shown that the product with the greater cotton percentage causes more impacts in the ecotoxicity, in the acidification/eutrophication and in the climate change, %, 13.04% and 4.39%, respectively, when compared to the product with the greater amount of polyamide. The increase in the indexes of the ecotoxicity and acidification/eutrophication causes negative impacts in the ecosystem quality. Increasing the effects in the climate change can affect negatively human life. Being the synthetic derived from crude oil, it is expected a sensible decrease in the fossil fuels as the percentage of polyamide is increased in the mixture. However, it was observed a small increase in 0.98% of product 2 relative product 1 and products 2 and 3 present the same index, probably due to the little difference in the polyamide percentage in the mixture. One can conclude that the product with 66 % of CO, 32 % of PA and 2 % of PU (product 3) causes less damage to the ecosystem quality and to human health and does not affect significantly the fossil fuels depauperation. 1. Introduction The concept of a LCA is defined, according to ISO 14040, as a technique to evaluate potential environmental impacts of a product through its life cycle (Finnveden et al., 2009; Gonzáles-Garcia et al., 2010). LCA study is done by the elaboration of an inventory of product entrances (energy, materials, etc.) and exits (energy, waste materials, products, etc.) in the system, by the evaluation of potential environmental impacts associated to this entrances and exits and by the interpretation of the results

2 from the analysis of the inventory and stages of the evaluation relative to the study objective (Azapagic, 1999; Banar and Cokaygil, 2008). The manufacturing of a textile product is composed by several operations like spinning, knitting or weaving, dyeing and printing, clothing and finishing. These processes represent a significant part of the global environmental impacts because they are water, energy and chemicals big consumers. Water is used as solvent and as a source of energy in steam generators in the dyeing, printing and finishing processes. Electricity is consumed in all of the processes with emphasis in the weaving process. Chemicals like pesticide, herbicide, bleaching, colorant, etc. are used since the obtainment of raw material until the final use in domestic washing. In the textile industry the products recycle and process optimization are techniques used to minimize effluents. These practices of repairing and treatment are insufficient to solve the environmental problem. It is necessary a holistic analysis about the environmental aspects by LCA, by analyzing every type of environmental impact caused by the product, including the raw material extraction, the emission of toxic substances, soil utilization, etc. In the last years comparative studies between types of products or processes have been done aiming to determine which product or process generates minor environmental impacts. Other studies determinate which stages of the process represent the greatest environmental impacts. Steinberger et al. (2009) applied LCA in two distinct textile garments, a cotton T-shirt and a polyester jacket, in order to highlight potential differences in environmental impact in the production and use and concluded that from a life cycle perspective, consumer education promoting air-drying and cool washing is more important than efficient appliances because the energy consumption in use phase creates greater environmental impact. Van der Werf and Turunen (2008) sought to quantify the major environmental impacts associated with the production of three hemp yarn production scenarios and a flax yarn production scenario using LCA. The comparison of these processes revealed that, overall, neither of the alternatives was unambiguously better than the other except for pesticide use (higher for flax) and water use (higher for hemp). 2. Purpose of the Study The main objective of this study is to apply LCA in a textile process, by comparing 3 types of sportive socks with the following composition: Product 1: 85 % of CO, 12 % of PA and 3 % of PU; Product 2: 70 % of CO, 27 % of PA and 3 % of PU; Product 3: 66 % of CO, 32 % of PA and 2 % of PU. It is necessary to identify which is the adequate composition for a white feminine sportive sock taking into account the environmental impacts in its manufacturing. The analysis was done from the cradle to the gate of the factory and empiric data from 2005 and the software Simapro 7 TM from Pre Consultants Inc. were used. 2.1 Functional unit The correct definition of functional unity is necessary in the comparative analysis of different products. It is not possible to compare a product A with a product B if they

3 have different performance characteristics. In this case the functional unity is a pair of white socks with 370 g. This choice does not take into account the life of the product. 3. Materials and Methods The studies were done in accordance with ISO 14040, dividing LCA in 4 stages: Objectives definition and scope (limits of the analysis), inventory analysis, impact evaluation and interpretation. Products were evaluated by using Simapro 7 TM. 3.1 Goal and Scope definition The objective of this work was to compare three types of sportive socks with variated compositions to choose, according to environmental impact criteria, which is the more appropriated composition. The scope of this study is to consider the production of raw material as cotton yarn, polyamide and polyurethane, the direct or indirect use of energy, chemicals and water. It was also considered the land carriage from the spinning to the tincture and from the tincture to the knitwear mill. Figure 1 shows the system. 3.2 Inventory analysis Data were collected from the literature and from Simapro 7 TM. Table 1 shows data used in this work. 4. Impact Assessment Results 4.1 Impact characterization The impacts evaluation was done by using the Ecoindicator 99 and the impact categories considered in this study were the ecotoxicity, acidification/eutrophication, climate change and fossil fuels. These categories have been considered in other LCA studies (Cadena et. al., 2009; Banar and Cokaygil, 2008). Table 1: Inventory data for 3 kinds of products: product 1 has 8 5% of CO, 1 2% of PA and 2 % of PU; product 2 has 70 % of CO, 27 % of PA and 3 % of PU; product 3 has 66 % of CO, 32 % of PA and 2 % of PU. Chemicals used in bleaching and dyeing Products / materials Units Product 1 Product 2 Product3 Soap G Sequestrating G Sodium hydroxide 50 % G Hydrogen Peroxide 50 % G Optical bleach G Water Human consumer water m Industrial water m Energy Natural gas (Boilers) MJ Electrical kw/h Waste Wastewater treatment m Spinning dyeing kg km dyeing knitting kg km

4 Cotton extraction Spinning of polyamide Spinning of cotton Spinning of polyurethane Energy Dyeing / Finishing Chemical manufacture: salt, dyes, bleaches, detergents, solvents, herbicides Knitting Water Waste Emissions Figure 1: System limits and processes considered in LCA. Figure 2 presents the results. The items are: (a) a ecotoxicity, whose unit represents the PAF*m 2 y (Potentially Affected Fraction per area per year), (b) acidification/eutrophication with unit expressed in PDF*m 2 y (Potentiality of Disappearing Fraction per area per year), (c) climate change, with unit expressed in DALY (Disability Adjusted Life Years), that corresponds to the incapacity of adjust of the years of life and (d) fossil fuels, represented in MJ surplus, that corresponds to the excess of the unit. The ecotoxicity is measured by the potentiality of water and soil contamination. In Figure 2a. It can be noted the greater potential of ecotoxicity in the product 1 (0,151 PAF*m 2 y), followed by products 2 (0.135 PAF*m 2 y) and 3 (0.129 PAF*m 2 y). This result shows that the greater the amount of cotton, greater is the potential of ecotoxicity. The acidification/eutrophication represents the perceptual of decreasing of the biodiversity about a specific area during a period. As in the case of ecotoxicity, there is a decrease in the potential of acidification/eutrophication from the product 1 (0.023 PDF*m 2 y) to the product 3 (0.020 PDF*m 2 y), according Figure 2b. There were no significant modifications in climate change, with a low tendency in decreasing from the products 1 to 3, according Figure 2c. Product 1 presented DALY, product 2 presented 3, DALY and product 3 presented DALY. Results presented in Figure 2d. Shown no significant influence of the products composition in the depauperation of fossil fuels. Product 1 presented 1.01 MJ surplus, and products 2 and 3 presented 1.02 MJ surplus.

5 Figure 2: Comparison of the environmental impacts of the 3 products. 5. Conclusions In the present paper Simapro 7 TM was used to the LCA study in a textile process. The software is easy to use and has a huge set of data. Being European, it is necessary some adaptations for countries in other continents. Comparing the results one can conclude that the product with the greater potential of cotton causes the biggest impacts in the ecotoxicity, in the acidification/eutrophication and in climate change, %, % and 4.39 %, respectively, when compared with the product with more polyamide. The increase in the ecotoxicity and in the acidification/eutrophication causes negative impacts in the ecosystem. The increase in the climate change affects negatively the human health. It can be concluded the product with 66 % of CO, 32 % of PA and 2 % of PU causes less damage to the ecosystem and to the human health. Being the synthetic fibers derived from crude oil, there was an expectation of greater alteration in the depauperation of fossil fuels with the increase in the percentage of synthetic fibers in the mixture. However, it can be observed a light increase in the depauperation of the fossil fuels, something about 0.98%, probably, due to the little difference in the composition. It could indicate that the fiber of cotton causes more environmental impact in its processes.

6 References Azapagic A., 1999, Life cycle assessment and its application to process selection, design and optimisation. Chemical Engineering Journal, 73, Banar, M. and Cokaygil, Z., 2008, A comparative life cycle analysis of two different juice packages. Environmental Engineering Science, 25, 4, Cadena, E., Colón, J., Artola, A., Sánchez, A. and Font, X., 2009, Environmental impact of two aerobic composting technologies using life cycle assessment. The International Journal of Life Cycle Assessment: LCA for Waste, 14, Finnveden, G., Hauschild, M. Z., Ekvall, T., Guinée, J., Heijungs, R., Hellweg, S., Koehler, A., Pennington, D., Suh, S., 2009, Recent developments in Life Cycle Assessment. Journal of Environmental Management, 91, González-García, S., Hospido, A., Feijoo, G., Moreira, M. T., 2010, Life cycle assessment of raw materials for non-wood pulp mills: Hemp and flax. Resources, Conservation and Recycling, 54, Steinberger, J. K., Friot, D., Jolliet, O. and Erkman, S., 2009, A spatially explicit life cycle inventory of the global textile chain. The International Journal of Life Cycle Assessment, 14, Van der Werf, H. M. G. and Turunen, L., 2008, The environmental impacts of the production of hemp and flax textile yarn. Industrial Crops and Products, 27, 1-10.