**4. Life cycle assessment of a denim fabric**

energy content, it can be used as a raw material to generate heat energy [47]. Solid waste from the textile industry can be used as a raw material to produce briquette. The thermal processes that are performed at high temperature with inadequate oxygen could generate carbon monoxide, which is a greenhouse gas. Therefore, a thermochemical conversion process, such as pyrolysis, is applied. Pyrolysis is referred to the decompositional process with high temperature in the absence of oxygen condition [47]. Products from pyrolysis are various, such as activated carbon fiber, char, bio-oil, and syngas. The variation of product is related to pyrolysis

Despite its growing popularity, there are numerous obstacles to textile recycling

1.Economic viability: Due to the widespread production of lower-grade products (downcycling) from textile recycling, many recycled textile wastes are unsuitable for multiple recirculation and use. Limited recirculation and reuse are not economically viable and discourages investment in textile recycling.

2.Composition of textile products: The base components of many textile products make them unsuitable for recycling. The presence of plastics and

3.Nonavailability of recyclable textile materials: A limited quantity of used textiles and textile waste are collected and sorted for recycling, and the quantity that is suitable and accessible for recycling is insufficient.

4.Technological limitations: One of the main reasons for the limited quantity of recyclable materials is the lack of technologies for sorting textile waste in preparation for recycling. Dyes and other contaminants cannot be separated

5.Lack of information and limited public participation: Limited public awareness on the merits of recycling contributes immensely to the low recycling rate,

6.Poor coordination, weak policies, and standards: Uncoordinated collection of waste and absence of an integrated and well-coordinated framework and policies to enhance the overall efficiency of the textile recycling are identified

There are also some constraints and challenges faced specific to denim recycling processes [29, 49]. Collection and sorting of worn-out jeans is timeconsuming and laborious. Labels; metal parts like rivets, zippers, and buttons; and leather patches have to be removed manually from the jean before shredding. Generally, the metal and leather parts are removed, but it is more difficult to remove the labels, and therefore jeans are sent along with them. The consequence is that the labels contaminate the recycled denim material as they are made of other materials. Any metal parts present on the jean to be recycled may cause problems to the machinery and process. It is easier to remove buttons and zippers by using gravitation but since rivets are too small and too light, special care is

[47–48]. The major ones to the optimization of textile recycling are:

metals in textile products hinders their recyclability.

from the original fibers by most of the existing methods.

condition.

**3.2 Challenges in recycling denim**

*Waste in Textile and Leather Sectors*

causing market inefficiency.

as barriers to efficient recycling.

needed to remove them.

**68**

Life cycle assessment (LCA) is a methodology where the environmental performance of a product or service is assessed starting from the raw material extraction point to the end of life of that product/service, i.e., from "cradle to grave." The methodology of LCA is defined under the ISO 14040/44 Standard [50].

For a pair of denim jeans, the life cycle (**Figure 2**) starts with the production of raw materials such as fibers and chemicals. These materials are then transported to fabric manufacturer and processed to become a fabric. During fabric production, energy and water are consumed in addition to raw materials while emission to air and to water and production waste are generated. The following process for the fabric is garment manufacturing in which the fabric is cut, sewn, washed, and accessorized (rivets, buttons, etc.) according to the design. Finally, the finished garment is sent to a warehouse or directly stores to be sold. After it is bought, the garment is washed and dried (or dry-cleaned depending on its nature) many times throughout its use phase. When it completes its life span, the garment has various "end of life" scenarios such as recycling, reused, refurbished, and disposed in landfill or incinerated, etc., which were discussed in the previous sections.

Life cycle assessment (LCA) helps us analyze the environmental performance of denim production in a transparent and systematic way and identify the hot spots.

**Figure 2.** *Lifecycle of a jean.*
