*Understanding Denim Recycling: A Quantitative Study with Lifecycle Assessment Methodology DOI: http://dx.doi.org/10.5772/intechopen.92793*

5%, eutrophication drops by 8%, and abiotic resource depletion drops by 3% with each addition of 10% recycled content in the blend.

Global warming potential, in other words climate change impact, is affected by two main stages: fiber cultivation and spinning. The energy usage in spinning increases when the recycled cotton content is increased, which implies a negative impact of the use of such fiber on global warming potential. However, since the percentage of the virgin cotton usage is decreased, this decline delivers a high positive impact for global warming potential, lessening the effect of energy usage.

In eutrophication calculation, the main effect derives from usage of fertilizers, pesticides, and insecticides at farm level. During irrigation of cotton, the probability of water pollution caused by these chemicals increases. Once the usage of virgin cotton decreases in the blend, the value of eutrophication decreases. Overall, the decrease results as 8% with a use of 10% recycled cotton.

Water use and land use impacts decrease by 10% with an addition of 10% recycled cotton. Since cotton uses land, and a high amount of water in the field during cultivation, avoiding the use of virgin cotton creates a high decrease in impact categories. If one can spin and weave a blend of 50% virgin and 50% recycled cotton, the overall impact on these two categories decreases 50%, which is a considerable figure when the amount of fabric produced reaches approximately 3 billion meters annually.

#### *4.3.4 Impact of organic cotton and recycled cotton*

This section aims to determine the impact of blending recycled cotton with organic cotton. Organic cotton data used in the calculations is generated from the literature [78–79]. The percentages used in the life cycle assessment (LCA) calculations are as follows:


Once organic cotton is used, at least 25% decrease appears in three categories: namely, global warming potential, eutrophication, and abiotic resource depletion. The decrease in water use (11%) is comparably low. On the other hand, real decrease happens in the land use, nearly 40%. This is due to the data for Aegean Region organic cotton. The yield in Turkish organic cotton is comparably high. The land use for 1 kg of lint organic cotton is 4.65m<sup>2</sup> for Turkish organic cotton. The same figure appears to be 19.7 for global production and 20.9 for the US organic cotton (**Figure 6**).

The virgin cotton used in study for calculations is a blend of the US, Turkish, Greek, and Brazilian cotton.

The results of the life cycle assessment (LCA) calculations are presented in **Figure 7**. The data shows that diverting from 100% regular cotton to 100% organic cotton reduces global warming potential by 27%, eutrophication by 26%, abiotic depletion by 24%, and land use by 39%. In addition, as in Article A-7, blending organic cotton with 20% recycle cotton generates an additional 10% decrease in land use. With the aid of this blend, the comparably lowest impact in land use is achieved in this study. The same is true for global warming potential and abiotic depletion. Article A-7 has the lowest values compared to the rest of the articles in **Figures 5** and **7**.

In each version, the recycled cotton content was increased by 10%. The recycled cotton used in the calculations is post-consumer recycled cotton, and its industrial data such as production and transportation data is obtained from a local supplier. The results of the life cycle assessment (LCA) calculations are presented in **Figure 5**. As may be seen from these results, global warming potential decreases by

**Figure 4.**

**Figure 5.**

**74**

*Five environmental impacts of selected fabric according to process steps.*

*Waste in Textile and Leather Sectors*

*Results of LCA calculations of virgin and post-consumer recycled cotton blends.*

into the article's process steps starting from cradle, meaning cotton cultivation, to gate, the end of fabric production. When it is analyzed (Section 4.3.2), one can see that fiber has more than 50% of the total impact in four out of the five categories. Only in abiotic depletion, warp preparation and dyeing have a greater effect than that of the fiber itself. Since recycled cotton usage means eliminating the fiber growing stage or in other words not using virgin raw material that requires natural resource, the environmental impact decreases as the recycle content increases in the fabric. And this is mainly true for global warming potential, eutrophication, water use, and land use. Especially for water and land use, fiber growth stage has more than 90% impact on the overall score. Fifty percent recycled cotton use decreases both impacts by 50%. Therefore, it is better to use recycled content to decrease the

*Understanding Denim Recycling: A Quantitative Study with Lifecycle Assessment Methodology*

Organic cotton with recycled cotton combination has the lowest impact in land use. Using 100% organic cotton also helps reduce global warming potential and eutrophication more than using 50% recycled cotton. However, when it comes to water use and land use, recycled cotton always scores the best since it is not a grown raw material. Here, one can question the production of recycling. The data related to production and transportations are taken into account in the LCA calculations. In conclusion, denim recycling is very crucial to reduce the water and land use impact of jeans. Combining recycled cotton with organic cotton also leads to reductions in other impact categories such as eutrophication, global warming potential, and abiotic depletion as well. As a future study, the impact of different fibers used in denim fabric production may also be analyzed with a combination of recycled

Recycled cotton source appears to be the first challenge when whole textile system is considered. There are regulations in countries either limiting or declining the import of second-hand garments. This creates a limitation in source since the

The second challenge is the composition of jeans. Historically, the main composition was 100% cotton. Right now, more than half of the jeans include elastane fiber as well. Besides elastane, new compositions include man-made fibers and regenerated cellulosic fibers. The more complex the composition, the harder it gets

The most important challenge here is always the consumer mindset. Across the industry, only 13% of the total material input is in some way recycled after clothing use. Most of this recycling consists of cascading to other industries and is used in lower-value applications, for example, insulation materials, wiping cloths [81], Once discarded, over half the garments are not recycled but end up in mixed household waste and are subsequently sent to incinerators or landfill. According to a McKinsey analysis, as was mentioned before, an average consumer buys 60% more clothes per year than 15 years ago but keeps the clothes only half the time, and this really is shocking once the numbers become visible [82]. Consumer awareness

Since mechanical recycling technique is a challenge in the process, recently, new

techniques have emerged to use denim jeans and other cellulosic materials as a source/raw material. Companies like Re:newcell, Infinited Fibers, and Nanollose are

collection of second-hand garments is not organized in some countries.

should be increased via marketing channels and mainly in schools.

environmental impact of water and land use mainly.

*DOI: http://dx.doi.org/10.5772/intechopen.92793*

cotton.

**4.5 Challenges**

to recycle jeans mechanically.

**5. Future of denim recycling**

**77**

**Figure 6.** *Land needed for 1 kg lint organic cotton, m<sup>2</sup> [80].*

On the other hand, eutrophication and water use remain higher than those of the articles in **Figure 5**. Organic cotton still uses a decent amount of water during cultivation. Therefore, Article A-7 could not result with the lowest impact on water use and eutrophication.

#### **4.4 Discussion**

Fiber selection stage—in this study fiber cultivation stage—has the main role in environmental impact of a denim fabric. Selected five impact categories are divided

## *Understanding Denim Recycling: A Quantitative Study with Lifecycle Assessment Methodology DOI: http://dx.doi.org/10.5772/intechopen.92793*

into the article's process steps starting from cradle, meaning cotton cultivation, to gate, the end of fabric production. When it is analyzed (Section 4.3.2), one can see that fiber has more than 50% of the total impact in four out of the five categories. Only in abiotic depletion, warp preparation and dyeing have a greater effect than that of the fiber itself. Since recycled cotton usage means eliminating the fiber growing stage or in other words not using virgin raw material that requires natural resource, the environmental impact decreases as the recycle content increases in the fabric. And this is mainly true for global warming potential, eutrophication, water use, and land use. Especially for water and land use, fiber growth stage has more than 90% impact on the overall score. Fifty percent recycled cotton use decreases both impacts by 50%. Therefore, it is better to use recycled content to decrease the environmental impact of water and land use mainly.

Organic cotton with recycled cotton combination has the lowest impact in land use. Using 100% organic cotton also helps reduce global warming potential and eutrophication more than using 50% recycled cotton. However, when it comes to water use and land use, recycled cotton always scores the best since it is not a grown raw material. Here, one can question the production of recycling. The data related to production and transportations are taken into account in the LCA calculations.

In conclusion, denim recycling is very crucial to reduce the water and land use impact of jeans. Combining recycled cotton with organic cotton also leads to reductions in other impact categories such as eutrophication, global warming potential, and abiotic depletion as well. As a future study, the impact of different fibers used in denim fabric production may also be analyzed with a combination of recycled cotton.

#### **4.5 Challenges**

Recycled cotton source appears to be the first challenge when whole textile system is considered. There are regulations in countries either limiting or declining the import of second-hand garments. This creates a limitation in source since the collection of second-hand garments is not organized in some countries.

The second challenge is the composition of jeans. Historically, the main composition was 100% cotton. Right now, more than half of the jeans include elastane fiber as well. Besides elastane, new compositions include man-made fibers and regenerated cellulosic fibers. The more complex the composition, the harder it gets to recycle jeans mechanically.

The most important challenge here is always the consumer mindset. Across the industry, only 13% of the total material input is in some way recycled after clothing use. Most of this recycling consists of cascading to other industries and is used in lower-value applications, for example, insulation materials, wiping cloths [81], Once discarded, over half the garments are not recycled but end up in mixed household waste and are subsequently sent to incinerators or landfill. According to a McKinsey analysis, as was mentioned before, an average consumer buys 60% more clothes per year than 15 years ago but keeps the clothes only half the time, and this really is shocking once the numbers become visible [82]. Consumer awareness should be increased via marketing channels and mainly in schools.
