Life cycle assessment of cotton textile products in Turkey

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Life cycle assessment of cotton textile products in Turkey G. Baydar a , N. Ciliz a,b,∗ , A. Mammadov a,b a b

Bogazici University Institute of Environmental Sciences, 34342 Bebek, Istanbul, Turkey Bogazici University, Sustainable Development and Cleaner Production Center, 34342 Bebek, Istanbul, Turkey

a r t i c l e

i n f o

Article history: Received 11 December 2014 Received in revised form 10 August 2015 Accepted 11 August 2015 Available online xxx Keywords: Textile industry Organic agriculture Cleaner production Life cycle assessment

a b s t r a c t Cotton textile and clothing industry is a complex and multi-tiered system that consists of cotton cultivation and harvesting, fiber production, yarn manufacturing, fabric preparation, fabric processing that includes bleaching and dying sub-processes among others and fabrication of the final product. An array of environmental concerns are associated with this sector, the most significant of which are issues related to use of agrochemicals in the cultivation of cotton and water, energy and chemical consumption in the fabric processing stage. Textile industry is a significant contributor to the Turkish economy constituting 18% of total export volume in 2013 according to Turkish Statistical Institute. In the study, environmental impacts of Eco T-shirts produced from organically grown cotton and processed with green dyeing recipe were compared to that of conventional T-shirts, in terms of their contributions to global warming, acidification, aquatic and terrestrial eutrophication and photochemical ozone formation using life cycle assessment methodology. The results reveal that Eco T-shirts have lower impact potentials across all inspected categories, with the most dramatic reduction in aquatic eutrophication potential (up to 97%) due to elimination of nitrogen and phosphorus containing chemical based fertilizers. The results also show that global warming potential is by far the largest environmental impact for both conventional and Eco T-shirts with the main impact coming from use phase, followed by cultivation and harvesting and fabric processing phases. The results of the analysis underline the importance of utilizing sustainable raw materials in all life cycle stages of cotton textile products and the necessity of focusing on the consumer behavior and sustainable practices in the use phase of the products as well. © 2015 Elsevier B.V. All rights reserved.

1. Introduction The textile and clothing sector consists of a wide number of subsectors, from sourcing of raw materials (fibers) to semi-processed (yarns, woven and knitted fabrics with their finishing process) and final consumer products (carpets, home textiles, clothing and industrial use textiles). The complexity of the sector complicates a clear-cut classification system for the different activities involved (EC, 2001a,b). Fibers used in the textile industry are classified into two main categories: natural and man-made. The natural fibers are derived from vegetable or animal sources. In the year 2010, man-made fibers and natural fibers shared about 60.1% and 39.9% of global textile fiber consumption, respectively. Cotton is the most widely utilized natural fiber in the world, accounting for over 82% of global natural fiber consumption (FAO-ICAC, 2013). Approximately 32.4 million hectares of agricultural land area is

∗ Corresponding author at: Bogazici University, Sustainable Development and Cleaner Production Center, 34342 Bebek, Istanbul, Turkey. Tel.: +90 212 359 6947; fax: +90 212 257 5033. E-mail address: [email protected] (N. Ciliz).

allocated for cotton plant, grown in more than 75 countries. The latest figures for the 2013/14 season show world lint production at 25.6 million tons with six countries: China, India, USA, Pakistan, Brazil and Uzbekistan, accounting for about 80% of total production and the remainder is spread across a large number of smaller producers, with Turkey ranking 7th following Uzbekistan (FAO-ICAC, 2015; USDA, 2015). Textile and clothing sector constitutes an important part of Turkey’s economy with the export volume of 27.7 billion USD in the year 2013, which corresponds to 18% of all the total exports (TUIK, 2013). Cotton cultivation has also been constantly expanding to accommodate the growing demand of the textile industry, reaching 2.25 million ton production in 2013 (TUIK, 2013). The complex nature of textile products’ life cycle as well as impacts they have on the environment require comprehensive assessment methodology to evaluate potential environmental burdens in the context of sustainability approach. One such approach, namely life cycle assessment (LCA), provides successful interpretation associated with the whole cycles of selected products, services and processes. This methodology, standardized by ISO 14040:2006 and 14044:2006 is a decision support tool for evaluation of environmental impacts of products and services, required for a particular

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unit of function and includes compilation and meaningful evaluation of all inventory data associated with those products. 1.1. LCA of textile products LCA methodology has been widely applied in textile industry to evaluate various aspects and life cycle stages of the products, from cultivation and fiber production up until fabric processing and disposal of used products. Barber and Pellow (2006) aimed to determine total energy use and carbon dioxide emissions of New Zealand merino wool. Results showed that merino wool fiber production required a total energy use of 46 MJ/kg half of which occurred on farm and that on-farm activities accounted for two thirds of carbon dioxide emissions. Morley et al. (2006) evaluated recycling/recovery/reuse options for second-hand clothing and observed that, in the context of the CO2 emissions from waste management choices, the reuse of clothing has a significant benefit over recycling or disposal. It is stated that the maximum reuse benefits are of the order of 33 kg CO2 -eq/kg clothing for a sample of cotton and polyester clothes, compared to a maximum of about 8 kg CO2 -eq/kg of fiber recycling, citing the study conducted by Marks & Spencer that showed extracted energy of cotton product and fiber manufacture as 5.3 times greater than cotton manufacture alone and 2.9 times greater when comparison is done for polyester clothes. Woolridg et al. (2006) demonstrated that for every kilogram of virgin cotton displaced by second-hand clothing approximately 65 kWh is saved, and for every kilogram of polyester about 90 kWh is saved. University of Cambridge, Institute for Manufacturing evaluated cotton, viscose and nylon fibers with polypropylene and latex-foam backing with LCA methodology. Results of the study indicated that the key environmental impacts of the sector resulted from use of energy and toxic chemicals (Allwood et al., 2006). Chalmers University of Technology in Sweden conducted an LCA for three fabrics types for a sofa made of conventional cotton, Trevira CS (a flame retardant polyester) and wool/polyamide. The study concluded that Trevira CS was preferable in terms of minimizing environmental impact when choosing between the three fabric types and the cotton sofa cover was a less favorable choice. The results of the project indicated that the most significant impacts were from cultivation and wet treatment of the fabric (Dahllöf, 2004). Kalliala and Nousianinen (1999) compared and evaluated different hotel textiles: cotton and cotton–polyester sheets and concluded that cotton–polyester sheets in hotel use have fewer environmental impacts than cotton sheets. The reason was the higher durability as well as lower laundering energy requirements of cotton–polyester sheets. LCA is also widely applied by the private sector to evaluate the impacts of not only technical and factory settings but also policy changes and user behavior and habits on the environmental performance of textile products. Marks & Spencer conducted LCA to assess the energy requirements for life cycle of a pair of pleated polyester trousers and a pack of men’s cotton briefs. According to findings, consumer use corresponds to 76% and 80% of the life cycle energy needs, respectively (Collins and Aumônier, 2002). Design Mobel conducted a full LCA of products from raw material inputs, through manufacturing, to the use of waste by-products and design briefs. They sourced wood from sustainable forestry operations and used natural materials including bamboo, cotton, 100% natural latex and wool in natural manufacturing processes (SBN, 2008). An integrated and holistic approach is necessary when assessing the sustainability of textile products since actions in one phase of product’s life cycle can have direct and indirect effects in other phases and the overall environmental performance. An LCA study on bed-sheets conducted by Saxce et al. (2012) demonstrated that textile product quality parameters, such as lifetime of a product and ease of care that are determined in the manufacturing phase,

can have significant influence throughout product’s life cycle; removing the need for ironing and increased lifetime lead to overall decrease in environmental impacts, although the effect of prolonged lifetime are much prominent than that of other product parameters. The goal of this study was to identify and compare the environmental impacts of conventional cotton T-shirt and three different variants of Eco cotton T-shirt that supply the same functional specification. Potential environmental impacts are assessed considering cultivation and harvesting, raw material supply, ginning, spinning, knitting followed by fabric wet processing and finishing for manufacturing, service/use and disposal stages of the selected cotton T-shirts. The products were compared by taking into account sustainable cultivation methods and eco-efficient dyeing recipes. 2. Methodology and selected scenarios The functional unit of the LCA model was determined as 1000 items of knitted and dyed cotton T-shirt with a total weight of 200 kg and all results in the manuscript are expressed in terms of this common unit. The service life time of T-shirts was chosen as three years that covers 50 washing cycles at 60 ◦ C temperature. Life cycle processes included in the analysis and system boundaries are illustrated in Fig. 1. Organic cotton growth, organic farming productivity considerations and chemical substitution and reduction of dye-house applications constitute the main focus points in the analysis. Secondary products such as cotton-seed and fabric scraps are not taken into account in terms of neither on-site recycling nor industrial symbiosis due to lack of reliable data. Four different life cycle analyses were carried out for T-shirts. Developed scenarios were grouped into three key themes representing major changes in cotton T-shirt chain: changes in raw material selection, agricultural productivity and means of fabric wet processing (Table 1). The consequences of these differences are explored and measured for each scenario in accordance with life cycle perspective. GaBi 5 LCA modeling software complemented with comprehensive, up-to-date inventory databases and impact assessment methods was used to conduct LCA for the selected products in this study. Internationally recognized impact assessment method, The Environmental Development of Industrial Products (EDIP) 2003 developed by the Institute for Product Development (IPU) at the Technical University of Denmark was implemented in the evaluation phase. EDIP 2003 methodology is a problem-oriented approach, where the environmental impacts are modelled in the cause-effect chain. The methodology provides spatial differentiated characterization factors but, can be used both in a site-generic and in a sitedependent fashion (Hauschild and Wenzel, 2000). In this LCA study, site-generic characterization factors are applied to calculate environmental impact potentials of investigated cycles. The characterization factors for the global warming potential (GWP) are based on the IPCC recommendations. Organic substances and carbon monoxide from fossil fuels are included with the assumption that they will end up as carbon dioxide eventually. In calculating the acidification potential (AP), Regional Acidification Information and Simulation (RAINS) computer model is used to assess the fate of emissions and the exposure quantities to ecosystem. The same model is used in calculation of terrestrial eutrophication potential (TEP). Cause effect Relation Model to support Environmental Negotiations (CARMEN) model is used to assess the fate of nutrient emissions to water in calculating the aquatic eutrophication. The transport of nutrients from agricultural supply and atmospheric deposition through groundwater drainage and surface runoff or topsoil erosion to surface water is considered within the model. Photochemical ozone formation potential (POFP) resulting from

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Fig. 1. Life cycle system boundaries of the selected cotton T-shirts.

VOC and NOx emissions is considered within EDIP methodology and exposures to both human and plant life are assessed again with RAINS model. Separate characterization factors are available for individual emissions but VOCs are expressed via common factor (Danish Ministry of Environment, 2005).

3. Life cycle of a conventional and Eco T-shirts The life cycle stages of conventional and Eco T-shirt variants are similar, as indicated in Fig. 1. The differences lay in cotton cultivation and fabric wet processing applications.

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Table 1 Life cycle scenarios for conventional and Eco T-shirts.

Table 2 Major insecticides used in cotton cultivation (Kooistra and Termorshuizen, 2006a,b).

Scenario

A

B

C

D

Product

Conventional T-shirt 0.2 1000 25.93

Eco T-shirt

Eco T-shirt

Eco T-shirt

0.2 1000 25.93

0.2 1000 25.93

0.2 1000 25.93

Conventional cotton 100

Organic cotton 100

Organic cotton 75

Organic cotton 50

Weight (kg) Pieces Total mass loss (%) Raw material Cultivation productivity (%) Wet processing

Conventional bleaching

Green dyeing recipe

Green dyeing recipe

Green dyeing recipe

3.1. Cotton cultivation and harvesting Although cotton is native to tropical and subtropical regions, it is grown in a very broad range of climates and soils using diverse agricultural practices (Cherrett et al., 2005). The key elements for successful cotton growing are temperature, sunlight, soil, supplemental nutrients, crop protection, rainfall and irrigation. Although cotton plant’s tolerance to temperature varies from species to species, it is primarily grown at temperatures between 11 ◦ C and 25 ◦ C (UNCTAD, 2002a,b). Cotton plant is grown on a wide range of soils but medium and heavy textured, deep soils with good water holding capacity are preferred for productive cultivation (Kooistra and Termorshuizen, 2006a,b). Cotton is a very waterintensive crop; it is estimated that cotton growing results in 1–6% of the world’s total freshwater withdrawal. In order to produce 1 kg of cotton lint, 10,000–17,000 L water is required (Kooistra and Termorshuizen, 2006a,b). Innovative irrigation techniques like drip irrigation, can lower the water demand for cotton production down to 7000 L/kg-lint (Soth et al., 1999). Nutrient uptake efficiency of cotton plant is rather poor and thus requires soil management practices and application of fertilizers. Common synthetic fertilizers used in fertility management are typically combinations of nitrogen (N), phosphorus (P) and potassium (K) (Silvertooth, 2002). Nutrient requirements of cotton under irrigation are 100–180 kg/ha N, 20–60 kg/ha P and 50–80 kg/ha K (Kooistra and Termorshuizen, 2006a,b). Crop rotation is an alternative practice to fertilizer application for achieving soil fertility (Guerena and Sullivan, 2003). In order to protect the cotton plant from potentially yield lowering insects and weeds, large quantities of acutely toxic chemical pesticides and herbicides are used in cultivation. Effectiveness of a particular insecticide can vary greatly from field to field, depending on previous insecticide use, pest species, and levels of resistance (Catchot, 2007). The predominant class of pesticides used in cotton cultivation are listed in Table 2 (Kooistra and Termorshuizen, 2006a,b). Herbicides are widely used in cotton cultivation for weed control along with traditional hand hoeing and mechanical tillage. The most important herbicide types used in cotton cultivation are listed in Table 3 (Kooistra and Termorshuizen, 2006a,b). 3.1.1. Conventional cotton cultivation Conventional cotton farming systems represent nearly 80% of the world’s cotton production and includes wide range of farms sizes, agrochemical inputs and outputs, energy and production efficiencies and related environmental impacts (Kooistra and Termorshuizen, 2006a,b). The input/output values and decision criteria in the study were defined according to selected reference area; the Antalya region in the South of Turkey. In 2004, the average crop yield in Antalya was determined as 3100 kg

Designation of the substance

Chemical group of the substance

Toxicity class (WHO)

Share (%) in the global cotton insecticide market

Deltamethrine LamdaCyalothrine Monoctrotophos AlphaCypermethrine Chlorpyriphos Esfenvalerate Methamidophos Dimethoate

Pyrethroid Pyrethroid

II III

12 9

Organophosphorus Pyrethroid

Ib II

9 8

Organophosphorus Pyrethroid Organophosphorus Organophosphorus

II II Ib II

7 7 6 5

Ib: highly hazardous; II: moderately hazardous.

Table 3 Major herbicides used for cotton cultivation (Kooistra and Termorshuizen, 2006a,b). Designation of the substance

Chemical group of the substance

Toxicity class (WHO)

Applied area (%)

Trifluralin Msma Fluometuron

Dinitroanilin Organoarsenic Substituted urea Dinitroanilin Substituted urea Substituted triazine Substituted triazine

U n.l. U

55 29 44

III U

28 12

U

19

lb

18

Pendimethalin Diuron Prometryn Cyanazine

Ib = highly hazardous; III = slightly hazardous; U = Unlikely to be hazardous; n.l. = not listed.

seed-cotton/ha (approximately 1100 kg-lint/ha), although this yield also depends on whether or not modern agriculture practices are applied (Canakci et al., 2005; Yılmaz et al., 2005). Studies performed in Antalya point to excessive nitrogen fertilizer consumption in the region (Canakci et al., 2005; Yılmaz et al., 2005). Emissions resulting from N and P fertilizer application are taken into account and quantified using methods for estimating on-field nitrogen and phosphorus emissions (Brentrup et al., 2000). Since, there is a wide variety of pesticides, insecticides and fungicides in use, a representative chemical was selected for each category of agrochemicals in the study, namely, diuron as a herbicide, parathion-ethyl as an insecticide and maneb as a fungicide. Application of growth enhancers and defoliation agents is not a common practice in Turkey (Kooistra and Termorshuizen, 2006a,b). The total dose of chemicals vary between 1.85 kg/ha and 10.5 kg/ha in the selected region (Canakci et al., 2005; Yılmaz et al., 2005). Harvesting is removal of opened and matured bolls (raw seedcotton) from the cotton plant and can be done either mechanically or manually. The cotton is picked by hand in Turkey (Chaudhry, 1997; Yılmaz et al., 2005). 3.1.2. Organic cotton cultivation Organic cotton production is a system of growing cotton without synthetic chemical fertilizers, herbicides, insecticides, growth regulators, growth stimulators, boll openers or defoliants (Ingram, 2002). In order to be certified as organic, cotton has to be grown without the prohibited chemicals for a period of three years. The yield can be reduced by up to 50% in the first few years after switching to organic practices but, the studies show that production yields go back to its original level and in few cases even higher after three

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years (Kooistra and Termorshuizen, 2006a,b; OE, 2007; Lakhal et al., 2008). Turkey contributed to 32.76% and 39.76% of the global organic cotton production in 2005/06 and 2006/07 growing seasons, respectively (OE, 2007, 2006). However, obtaining the exact cultivation and consumption figures in Turkey is challenging due to discrepancies between the declared and real volumes of traded organic fiber (Ton, 2007; OE, 2008a). Detailed information about organic cropping systems in Turkey is not yet available (Kooistra and Termorshuizen, 2006a,b; OE, 2007, 2006). Thus, three different yield productivity scenarios for organic cotton cultivation were developed; for transition period it is assumed that production rate is half of the original year (550 kg/lint-ha), after transition it is equal to 750 kg/lint-ha and finally average crop yield for organic cotton cultivation is same with conventional cotton production rate (1100 kg/lint-ha). Since organic cotton growing requires an upgraded system of farming where soil management is one of the highest priorities, it is assumed that natural fertilizers are used to maintain soil fertility. In order to provide efficient N, P and K, composting, rock phosphate and muriate of potash are used in place of synthetic fertilizers (UNCTAD, 2002a,b; Laursen et al., 1997; OE, 2008b). Certification requirements prohibit use of toxic pesticides against insects, weeds and diseases (ICAC, 1994). It is assumed in the study that no agro chemicals or their alternatives are used in the production of organic cotton and pest, weed and disease management is achieved through crop rotation. Irrigation water consumption for organic cultivation is assumed to be same with conventional cotton water requirement. 3.2. Ginning, yarn manufacture and knitting Cotton ginning separates lint fiber from cotton-seed while removing the trash from seed cotton and lint fiber and acts as a bridge between agricultural cotton production and textile manufacturing (Proto et al., 2000). Electric power requirement among gins usually range from 40 to 60 kWh/bale (Anthony and Mayfield, 1994). Yarn production from staple fibers involves opening, cleaning, blending, carding, combing, drawing, roving and spinning (Bralla, 2007). According to a recent study performed in Turkey, process energy consumption changes between 11.62 and 13.53 MJ/kg (Koc¸ and Kaplan, 2007). The energy consumption in this study is assumed as 12.85 MJ/kg yarn and mass loss quantities are 5% for preparation and 5% for spinning. Knitting is a purely mechanical method of fabric formation and includes knotting yarn together with a series of needles (EC, 2001a,b, U.S.EPA, 1997). The energy consumption for this process is about 5 MJ/kg and material loss is 3% on average. 3.3. Fabric wet processing Fabric wet processing improves the appearance, durability and serviceability of fabrics by converting undyed and unfinished goods into finished consumers goods. It involves three main stages: fabric preparation (pre-treatment), coloring, and finishing and many subprocesses. Pre-treatment removes natural sizing materials such as water-insoluble starches, non-cellulosic impurities and foreign matter like waxes, proteins, ashes and unwanted natural coloring (U.S.EPA, 1997, Aly et al., 2004). Dyeing is performed to give a uniform and permanent color to fabric. Dyeing processes constitute the main difference between conventional and Eco T-shirt products in this study, along with alternative cotton cultivation practices. The inventory data for wet fabric processing was provided by the selected textile plant located in Hadimkey, Istanbul where Cleaner Production (CP) options were

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developed and applied. The study served a dual purpose of determining and reducing the chemical, water and energy consumption from wet fabric processing at the plant and providing data for the LCA comparison of conventional and Eco T-shirt products. The general results are specified and expressed by using specific chemical consumption (kg/kg textile), specific water consumption (L/kg textile) and specific energy consumption (MJ/kg textile). Water used in dye-house is extracted from wells and softened by an ion exchanger. The softened water is distributed to the processes and used in dyeing baths and for cleaning purposes in the facility. Dye-house wastewater is treated on-site and discharged into sewer line. Natural gas and electricity are two major sources of energy in the plant. Part of natural gas is used for steam production in boilers. Wet processing of knitted cotton fabric in dye-house is carried out in jet dyeing machine. The sub-process of wet processing for both conventional and Eco T-shirts are bleaching, dyeing, washing, softening and drying. Conventional and green dyeing recipes presented in the study differ in bleaching and washing processes. CP audit has shown that bleaching is one of the highest water consuming unit operations in wet processing and increases the pollutant load of wastewater treatment plant. Bleaching process implemented in conventional T-shirt production consists of five cycles of water filling-draining that represents nearly 50% of total process time and one third of the total water consumption. Washing represents 55% of total water consumption and accounts for half of the generated wastewater. Shortening of process cycles in Eco T-shirt production reduced the specific water consumption and corresponding energy spending. Reduction affects not only the consumption of water but also the consumption of steam for heating up (up to 95 ◦ C) the process baths. Hydrogen peroxide (H2 O2 ) bleaching in conventional T-shirt production is both water and energy intensive. Reducing agent, sodium thiosulfate (Na2 S2 O3 ), is consumed to rinse off H2 O2 prior to dyeing. Moreover, H2 O2 bleaching requires strongly alkaline conditions which is achieved by addition of caustic soda. Additionally, wetting agent is used to give homogeneous hydrophility to the fabric and anti-pilling agent is added to degrade starch size on cotton fabric. Elimination of H2 O2 in the bleaching of Eco T-shirt fabric has resulted in 60% water and 61.5% energy saving without compromising the fastness properties of final product. Acetic acid, wetting agent and anti-pilling agent are applied in a series of two processes for Eco T-shirt fabric while oil-removing agent is omitted. Acetic acid and soap are used in washing stage in both conventional and Eco T-shirt fabric processing. Washing stage necessitates a number of rising cycles to remove unreacted and hydrolyzed dyestuff from the fabric after dyeing. Washing stage applied in conventional T-shirt production consists of eight-cycle water filling-draining. Soap substitution in washing eliminates three water filling-draining cycles resulting in 37.5% water and 38% energy saving. Apart from bleaching and washing processes, dyeing, softening and drying operations are similar in both recipes. Chemical, energy and water consumption values of conventional and Eco T-shirt production are as summarized in Table 4 and the exact values for each chemical are provided in Table 5. Total specific water consumption is reduced from 150 to 90 L/kg and 39.5% energy saving is achieved through above-mentioned modifications. 3.4. T-shirt making up, use and disposal The T-shirt making up processes do not involve environmental concerns beyond the use of electricity by machinery and fabric remnants produced during the cutting-to-size processes. Hence, only energy consumption and input/output of fabric mass values have been taken into account in evaluation. Average energy

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Table 4 Energy, water and chemical consumption values of conventional and Eco T-shirt production. Process

Preparation Coloration Finishing

Sub-process

Bleaching Dyeing Washing Softening Drying

Total

Chemical consumption (kg/kg textile)

Energy consumption (MJ/kg textile)

Water consumption (L/kg textile)

I

II

I

II

I

II

0.118 0.95 0.02 0.04 – 1.128

0.023 0.95 0.02 0.04 – 1.033

8.34 1.86 12.63 0.57 1.80 25.20

3.21 1.86 7.84 0.57 1.80 15.28

50 10 80 10 – 150

20 10 50 10 – 90

I: Conventional T-shirt, II: Eco T-shirt. Table 5 Inventory data for wet processing of conventional and Eco T-shirt per functional unit. Inputs/Outputs

Inputs Electric power Steam Water Wetting agent Desizing enzyme Acedic acid Sequestering agent Salt Soda ash Dyestuff Soap Cationic softener Silicon Anticrease agent Caustic soda Hydrogen peroxide Oil removing agent Stabilizer Sodyum thiosulphate Outputs Dyed fabric Fabric remnant Wastewater COD

Unit

Conventional T-shirt

Eco T-shirt

Scenario A

Scenario B

Scenario C

Scenario D

MJ MJ l kg kg kg kg kg kg kg kg kg kg kg kg kg kg kg kg

608.135 5348.848 35,460.000 2.364 0.709 9.456 4.728 165.480 47.280 9.766 2.364 4.728 2.364 2.364 5.910 5.910 1.182 1.182 2.364

447.995 3164.468 21,276.000 2.364 0.709 7.092 2.364 165.480 47.280 9.766 2.364 4.728 2.364

447.995 3164.468 21,276.000 2.364 0.709 7.092 2.364 165.480 47.280 9.766 2.364 4.728 2.364

447.995 3164.468 21,276.000 2.364 0.709 7.092 2.364 165.480 47.280 9.766 2.364 4.728 2.364

kg kg l kg

222.220 14.180 35,171.000 46.06

222.220 14.180 20,987.000 38.74

222.220 14.180 20,987.000 38.74

222.220 14.180 20,987.000 38.74

consumption of 2 MJ/kg textile is assumed with a fabric loss of 10% based on available literature (Laursen et al., 1997; BTTG, 1999). Only wearing and washing of T-shirts is included in the use phase while softening, drying and ironing are excluded. Energy, water and detergent consumption over the lifetime of one T-shirt that corresponds to 50 washes before disposal is considered in the study with the following assumptions; 60 ◦ C wash in an automatic washing machine, no prewash, 6 kg laundry mass load, 225 g detergent, 49 L tap water and 1.14 kWh energy consumption per wash. All calculations are adjusted to 1000 items. Incineration is the method of choice for disposal of T-shirts that completed their useful lifetime. 3.5. Transport Transport processes involved in the life cycle of T-shirts include seed-cotton transport, yarn transport, finished product transport and transport of used T-shirts to incineration plant. The inventory data for seed-cotton transportation is calculated based on average distance of 100 km traveled by diesel engine equipped truck with 12.4 t capacity. The average distance between yarn mill and knitting house is considered 750 km with the assumption that fabric production is performed in Istanbul. Fuel consumption and related emissions for transportation of 243.70 kg yarn are based on a diesel engine equipped truck process with 22 t capacity traveling from Antalya to Istanbul.

4. Impact assessment results of conventional and Eco T-shirts Conventional T-shirt and Eco T-shirt scenarios have been evaluated and compared in terms of their impacts to global warming, acidification, terrestrial and aquatic eutrophication and photochemical ozone formation potentials. Characterization results distributed by life cycle stages of the products are summarized in Figs. 2–6. Use, cultivation and harvesting, wet processing and yarn manufacturing processes have the highest impact potentials across all environmental categories evaluated in the study while impacts from transport processes, ginning, knitting, T-shirt makeup and disposal are less significant. The impacts from agricultural activities, wet processing and use phase originate from diverse effects of chemicals and energy sources used in the processes while impacts of yarn production are mainly associated with electric power consumption. The most dramatic decrease in impact potential when switching from conventional to Eco T-shirts was observed for aquatic eutrophication potential (AEP) which is due to elimination of nitrogen and phosphorus containing chemical fertilizers in cotton cultivation stage (up to 97% reduction). The differences in environmental impact potentials between Scenarios B, C and D, which vary in cultivation productivity, originate from the amount of fuel consumed by agricultural machinery operating in the field. The use stage has the highest GWP of 4140.4 kg CO2 -eq that results mainly from wastewater treatment, generation of electricity

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Fig. 2. Stage-by-stage GWP of conventional and Eco T-shirts.

Fig. 3. Stage-by-stage AP of conventional and Eco T-shirts.

Fig. 4. Stage-by-stage AEP of conventional and Eco T-shirts.

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Fig. 5. Stage-by-stage TEP of conventional and Eco T-shirts.

Fig. 6. Stage-by-stage POFP of conventional and Eco T-shirts.

for washing and detergent production. GWP associated with cotton cultivation and harvesting stage come from fertilizer and pesticide production (57%), N2 O emissions from the application of N fertilizer to land (22%) and agricultural machinery operations (19%) in the conventional cotton cultivation stage. Among all chemical inputs, N fertilizer production accounts for a significant portion (50.8%) of the impact. Elimination of chemical fertilizers and pesticides from cultivation process reduces GWP of Eco T-shirts. Positive performance of organic cultivation with a productivity rate of 100% is due to smaller cultivation land area and correspondingly less amount of diesel consumption by the agricultural machinery operations in the field. CP applications in wet processing led to decrease in GWP from 2420.7 to 1872.2 kg CO2 -eq (22%) in Eco T-shirts due to CO2 reduction through energy saving, chemical saving and direct emissions from breakdown of organic content during wastewater treatment. In terms of AP, use stage is an effective contributor to acidification with potential of 159.5 m2 UES across all scenarios. Wastewater treatment is the main contributor (51%) followed by soap production (25.3%) and electricity consumption (22.4%), while tap water usage has minimal effect. Shifting from conventional cotton cultivation to organic cultivation reduces AP by 74.7 m2 UES, 59.8 m2 UES and 44.9 m2 UES for scenarios B, C and D, respectively. Ammonia emission is the main source of the impact in conventional

cultivation resulting from supply and consumption of N fertilizer. N fertilizer consumption represents 75.56% of this value resulting from volatilization during and after application of urea, whereas N fertilizer production only accounts for 23.1% of total ammonia emissions. 17.0 m2 UES reduction in AP is observed when green dyeing recipe is implemented for scenarios of B, C and D, mainly from wastewater treatment process (70%). Steam used for heating and electricity used for mechanical work use are the two other significant contributors in this stage. AP for ginning (1.4 m2 UES), yarn manufacturing (16.4 m2 UES), knitting (6.24 m2 UES) and Tshirt making-up (2.1 m2 UES) stages are connected with electricity generation for processing. Cotton cultivation is the most significant cause of aquatic eutrophication in conventional T-shirts caused by nutrient enrichment from waterborne emissions of nitrate and phosphate originating from use of agrochemicals. AEP is reduced sharply from 43.561 to 1.460, 2.190 and 2.921 kg NO3 -eq when switching from conventional to organic cultivation methods used in scenarios B, C and D, respectively by replacing chemical fertilizers with natural alternatives. Nutrient enrichment is predominantly caused by NOx emissions deposited to marine areas in organic cultivation scenarios and by direct emissions to waster in conventional cultivation scenario. AEP from use stage (8.953 kg NO3 -eq) results from

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Fig. 7. Normalized impact potentials of conventional and Eco T-shirt scenarios.

nitrogen oxide and nitrate emissions originating from detergent production (4.194 kg NO3 -eq) and wastewater treatment (4.163 kg NO3 -eq), with power generation constituting only 6% of the impact from this stage. When conventional bleaching and dyeing recipe is compared with green dyeing recipe in the fabric wet processing stages, a reduction in AEP by 0.721 NO3 -eq (21.3%) is observed. TEP for conventional cotton cultivation stage is measured as 304.2 m2 UES in scenario A and reduced by 73%, 60% and 46% in Scenarios B, C and D, respectively. The reduction is achieved through complete elimination of ammonia emission and reduction in nitrogen oxides. Since, significant portion of nitrogen oxides originate from fuel consumption in agricultural machinery, the TEP from cultivation stage increases as agricultural productivity is reduced. 20% of decrease in TEP is observed when conventional bleaching dyeing recipe is replaced with green dyeing recipe since few chemicals are used in the process and process temperature is decreased while several baths are avoided. Use stage has the highest potential (247.1 m2 UES), resulting from wastewater treatment, soap production and power generation. Most of the POFP in conventional cotton cultivation comes from N fertilizer production and diesel combustion. Organic cultivation leads to a decline in the potential by 36.5% and 4.6% in scenarios B and C. However, contrary to other impact categories, a 27% increase is observed in Scenario D, due to inefficient utilization of agricultural land, which leads to increased consumption of diesel in farm machinery per processed area. 20.1% decrease (1926.4 m2 UES ppm hours) in POFP is observed when conventional bleaching dyeing recipe is replaced with green dyeing recipe, mainly due to reduction in wastewater treatment, steam consumption, saving in chemical consumption and finally power generation. Normalization scores given in Fig. 7 indicate that GWP is by far the largest environmental impact for both conventional and Eco Tshirt products. AEP, TEP and POFP have roughly similar impacts and constitute less than one third of GWP except in Scenario A where the effect of AEP is large due to chemical fertilizer use. AP has the lowest value among impact categories.

5. Interpretation of the results in terms of raw material substitution and centralized data availability The results presented in the study cannot be evaluated and accurately interpreted on a stand-alone basis without addressing the

issues of reliable data availability, supplier-end considerations and socio-economic aspects of the issue. Processes taking place at the supplier end of product’s life cycle in many cases may constitute the main portion of the product’s overall environmental footprint. Elimination of certain chemicals in wet processing has resulted in significant reduction across all impact categories. However, not all chemicals can be eliminated from the process chain. Thus, alternative reagents have to be tested and adopted for the currently used, high-impact chemicals to reduce the environmental burdens from the production phase. Improving the supplier-end performance of the product does not necessitate replacement of every chemical input in the process chain; some chemicals simply do not have currently available or economically feasible, viable alternatives. In those cases, attentions must be turned to manufacturers and suppliers of those materials and the ones with best environmental record and CP applications in place should be given a higher priority. This practice would not only reduce the environmental footprint of the product in question but, it would also improve the suppliers’ products by actively encouraging and pressuring them to manufacture their goods in a sustainable fashion. The results of the study show that transport has little impact in the overall life cycle of T-shirts and thus finding a better supplier, even ones from abroad must be pursued. The same premise is applicable to agro-chemicals such as fertilizers and pesticides used in cotton cultivation. While immediate transition to organic cotton cultivation might be challenging, gradual elimination of chemical based fertilizers and pesticides, starting from the ones with highest impact might be more feasible. Despite Turkey being one of the leading producers of organic cotton in the world, it was difficult to obtain reliable cultivation and consumption data. Crop productivity, type and application rates of fertilizers and pesticides vary significantly from country to country, from one region of a country to another and even from one field of a region to another, even for conventional cotton cultivation practices. Key parameters of cotton cultivation including average crop yield and fertilizers types and application amounts were available for the Antalya region in the South of Turkey. Pesticide, herbicide and fungicide types however varied significantly among different sources and thus representative chemicals for each of these three main chemical categories were used in the analysis. While overall results of the study indicate clear superiority of organic cotton cultivation over traditional practices in terms of environmental performance, it is important to acknowledge that regional differences such as soil fertility, climate and agricultural practice

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traditions strongly affect the sustainability of the final product. For instance, POFP from cultivation and harvesting phase in Scenario D where cultivation productivity is assumed to be 50% was highest among all scenarios including conventional cultivation phase. It is also important to realize that while process data for agricultural activities was obtained from literature and national reports and fabric processing data was provided by selected dye house operating in Istanbul, these data represent multiple, isolated sources thus, somewhat diminishing the general applicability of the results. Availability of centralized, verified and periodically updated national life cycle inventory database would greatly contribute to reliability and generalizability of the results of similar studies.

6. Conclusions and future considerations The results of the study point to importance of multi-directional approach where incremental interventions at different life cycle phases of a product lead to overall improvement of product’s sustainability. LCA study described in the manuscript was not construed as a validation of any production strategy but rather as a mechanism to evaluate different production and consumption strategies with the intent of improving knowledge and efficiency in terms of environmental consequences of products. Besides the obvious outcomes of chemical fertilizer elimination such as dramatic decrease in AEP, several aspects stand out; results show that diesel fuel consumption by agricultural machinery in the cultivation and harvesting phase, in addition to use of agrochemicals, is responsible for many environmental impacts from this stage, particularly global warming and these impacts increase as crop productivity decreases. Therefore, replacing diesel fuel with biodiesel in the machinery, preferably produced in an on-site facility from agricultural wastes and residues, would theoretically further improve sustainability of the final product provided that biodiesel itself is produced from sustainable feedstock. Electric power consumption is another prominent contributor to GWP along with other environmental impact categories across all life cycle stages of the products, most notably in use phase. Improving energy efficiency and increasing the share of renewable sources in fabric production and processing facilities and economic use of electricity in household would thus further increase the environmental performance of Eco T-shirts. The success of improving sustainability of T-shirts and similar textile apparel depends strongly on human factor across the entire value chain. Convincing the farmers to switching organic agriculture is the initial and the most important task in this endeavor. Unfamiliarity with the concept, concerns related to decreased crop yield and financial concerns that come along with it as well as adherence to proven, traditional methods among farmers are the main obstacles that need to be overcome. Although decrease in productivity is only temporary during the transition period to organic agriculture as supported by the literature, it is still a discouraging element to farmers who would suffer yield loss for a few years. Environmental issues associated with chemical fertilizer consumption can in many cases be of secondary concern for the farmers. It is important to note that transition to organic agriculture require collective and collaborative action by the farmers due to the very nature and definition of organic agriculture; for instance, pesticides and herbicides applied in the neighboring field could easily transport to a field where organic practices are applied, via wind or water, thus disqualifying their cotton from being organic. Therefore, mere publication of the results of the study is not sufficient and the main conclusions must be communicated on various platforms and disseminated to relevant stakeholders by proper governmental agencies, farmer unions and NGOs. The large impact from consumer use phase of the products in all environmental impact categories

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Further reading Chapagain AK, Hoekstra AY, Savenije HHG, Gautam R. The water footprint of cotton consumption: an assessment of the impact of worldwide consumption of cotton products on the water resources in the cotton producing countries. Ecol Econ 2006;60:186–203.

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