The development of technology in the textile recycling industry is facing a fundamental dilemma: mechanical recycling versus chemical recycling. These two approaches do not merely represent differences in processing techniques; they signify two fundamentally distinct philosophies in material recovery—philosophies that each carry profound, cascading implications for the quality of recycled fibers, economic viability, environmental impacts, and the feasibility of achieving a circular economy in the textile industry in the long term.

Understanding this distinction is essential for all stakeholders across the textile value chain—from manufacturers evaluating waste processing involvement to brands exploring strategies for sourcing recycled materials; from recycling companies planning investments in necessary facilities and equipment to policymakers designing circular economy frameworks.

The debate surrounding the choice between mechanical and chemical recycling is not merely academic. It directly determines the future development trajectory of infrastructure, economic models, and environmental consequences for the textile industry in the coming decades.

Mechanical Textile Recycling

Mechanical recycling is recognized as the most established and accessible method of textile recycling. In this process, textile waste is converted into fibers through mechanical operations of shredding, carding, and re-spinning, without breaking polymer bonds or significantly altering the material's chemistry.

The mechanical recycling process is carried out step-by-step. First, collected textiles are sorted by fiber type and color. They are then shredded into small pieces, typically 5 to 10 mm in size. These pieces subsequently undergo carding—a process with a centuries-old history in the traditional wool industry where fibers are separated and aligned parallel to each other. Finally, the carded fibers are re-spun into yarn using conventional textile machinery.

The attractions of mechanical recycling are significant. Its initial capital investment requirement is considerably lower than chemical methods. The capital needed to establish a mechanical recycling unit with a processing capacity of about 100 tons per day is approximately $2 to $5 million USD, whereas a chemical recycling plant with the same capacity is estimated to require about $10 to $25 million.

The mechanical recycling method is not overly complex; it does not require specialized chemical knowledge or the management of hazardous chemicals. Another advantage is its high process speed; according to available statistics, mechanical recycling facilities can easily achieve capacities exceeding 100 tons per day.

From a geographic accessibility perspective, mechanical recycling is a viable option in developing regions with limited significant capital. In secondary and tertiary cities, a mechanical recycling unit can be easily established without the need for advanced infrastructure. This geographic accessibility clearly explains why mechanical recycling is predominantly used in South Asia. For example, in India, thousands of small and medium-sized mechanical recycling units are operational.

 

Limitations of the Mechanical Recycling Method

The mechanical recycling method has one major technical limitation: the gradual degradation of fiber properties with each recycling cycle. The mechanical pressures from shredding, carding, and re-spinning cause fiber shortening and deterioration of the polymer's crystalline structure. This loss of properties is irreversible and intensifies with repeated processing cycles.

The average length of virgin polyester fibers is about 20 to 25 mm, whereas mechanically recycled polyester fibers average only 8 to 12 mm in length. This reduction in length essentially limits the range of end-use applications for these fibers. These short fibers cannot be spun into conventional yarns and are therefore primarily used in producing non-woven textiles and lower-value applications, including insulation, wadding, geotextiles, automotive interior trim, and other industrial uses.

Tensile strength diminishes proportionally. The average tensile strength of virgin polyester is around 70 to 90 Megapascals (MPa), whereas that of mechanically recycled polyester only reaches 40 to 50 MPa—a 30 to 40% reduction. Consequently, these fibers cannot be used in apparel production, which requires fibers with adequate durability and mechanical performance.

Color presents another challenge. When fibers are mechanically recycled, the colors from the original textiles are generally retained. Theoretically, this is an advantage, as it allows the use of colored fibers without the need for re-dyeing. However, in practice, mixing waste of different colors results in dull gray or brown fibers, necessitating re-dyeing. The catch is that achieving a color close to that of virgin fibers requires higher dye concentrations.

Downcycling

Given the property degradation in mechanical recycling, fibers can be reused for a maximum of 2 to 3 cycles. Beyond that, they become too degraded for further processing. This limitation is known as downcycling—the process of converting waste or useless products into new materials or products of lower quality and functionality. Its goals are to prevent the waste of useful materials, reduce consumption of fresh raw materials, lower energy use, and decrease air and water pollution and greenhouse gas emissions compared to primary production. A clear example is plastic recycling, which yields lower-grade plastic. For instance, a polyester shirt becomes insulation, in the next cycle it turns into low-quality felt, and ultimately ends up in a landfill. In this trajectory, the material's value continuously diminishes, and a truly closed loop in the circular economy is not achieved.

From a circular economy perspective, downcycling represents a failure of the fundamental principle of material circularity. Truly sustainable systems require infinite material cycles, but property degradation in mechanical recycling prevents achieving this goal.

Chemical Textile Recycling

The chemical recycling method is fundamentally different from mechanical recycling. In this process, polymer bonds are broken at the molecular level, and the constituent monomers are recovered, which can then be used as raw materials in new polymerization. Unlike mechanical recycling, where fibers are preserved in a shortened form, in chemical recycling, materials are broken down into their chemical building blocks.

The chemical recycling pathway depends on the polymer type. In the chemical recycling of polyester, several methods for depolymerization exist: glycolysis (reaction with glycols), hydrolysis (reaction with water), and methanolysis (reaction with methanol). In each method, the polyester is broken down into its constituent monomers—such as dimethyl terephthalate, ethylene glycol, or terephthalic acid—which, after purification, are re-polymerized to produce pure polyester indistinguishable from petroleum-derived materials.

The depolymerization process of Aquafil is an example of mature chemical recycling technology. Their proprietary hydrolysis method converts polyester waste into pure BHET (bis-hydroxyethyl terephthalate) with over 99% purity, suitable for direct re-polymerization into pure polyester fibers.

Similarly, Renewcell's Circulose technology dissolves cotton into a cellulose pulp, which fiber producers then regenerate into recycled cellulosic fibers with specifications identical to virgin cotton fibers.

The fundamental advantage of chemical recycling is that the properties of the recovered materials are equivalent to virgin fibers, and this is repeatable and endless. Theoretically, polyester recovered through depolymerization can be placed back into the produce–consume–recover–reproduce cycle repeatedly without any loss of properties. Fiber length, tensile strength, and color uniformity remain constant across all cycles. This capability enables **true circularity**. Chemically recycled polyester fibers can be reused over 100 times and, theoretically, infinitely. The economic value of the fibers is preserved across all cycles—the product is not of lower quality or cheaper than in the previous cycle—and environmental benefits are maintained over multiple generations of product life cycles.

Economic Realities

Cost Dynamics, a term first introduced by Michael Porter, refers to the fact that companies, in addition to analyzing cost behavior at a point in time, must also consider how the absolute and relative cost of value-adding activities changes over time. By adopting a cost dynamics strategy, companies can anticipate changes and respond quickly, gaining a cost advantage over competitors. Organizations need a solid understanding of cost dynamics to make decisions about product pricing, resource allocation, process improvement, and other strategic initiatives. For this purpose, businesses must continuously analyze their cost structure to interpret how different cost elements behave—i.e., identifying and examining cost drivers (e.g., labor, materials, machinery, equipment, etc.). Cost drivers help organizations allocate resources effectively and optimize their operations.

From the perspective of required initial investment, the scales tip in favor of mechanical recycling. Establishing a mechanical recycling plant with a 100-ton-per-day processing capacity requires an investment of approximately $3 to $5 million, whereas a chemical facility of equivalent capacity needs $15 to $25 million—a 4 to 6 times higher cost.

Operational costs also differ significantly. The operational cost of mechanical recycling is about $0.30 to $0.50 per kilogram of processed material, while that of chemical recycling ranges from $0.80 to $1.50 per kilogram, reflecting the greater process complexity, higher energy consumption, and chemical management.

These cost dynamics are challenging for chemical recycling. A mechanical unit can produce non-woven fibers at a cost of $0.50 to $0.80 per kilogram, and its products can compete directly with virgin non-woven materials at a similar price. In contrast, a chemical recycling plant produces high-quality fibers at a cost of $1.20 to $1.80 per kilogram, which must be marketed at a higher price. This higher price must be justified by superior material quality.

However, cost dynamics are changing. As chemical recycling capacity expands, unit costs decrease due to economies of scale. The cost of polyester recovered through chemical depolymerization has largely converged with that of virgin polyester, a crucial factor for market acceptance. It is expected that within the next 2 to 3 years, the cost competitiveness of chemical recycling will improve significantly.

Processing Capacity and Throughput

The simplicity of the mechanical recycling process enables high throughput. Modern mechanical facilities process 100 to 150 tons of waste per day with relatively simple equipment. Using a distributed network, mechanical facilities can process waste regionally and economically.

In contrast, chemical recycling capacity is lower than mechanical due to its more complex processes. An advanced chemical facility can process a maximum of 30 to 50 tons of textiles per day. This lower throughput results in fewer, larger facilities, leading to geographic concentration and increased logistics costs for feedstock collection.

However, the lower throughput of chemical facilities is compensated by the higher value of their output. Chemical recycling produces higher-quality fibers suitable for specific, premium applications, generating higher revenue per ton processed. The economic return of this method, even with lower processing volume, is greater than that of mechanical recycling.

Environmental Impacts

Mechanical recycling generally consumes less energy than chemical methods because it does not require high-temperature reactions, solvent recovery systems, or hazardous chemical management. From an energy perspective, the mechanical process typically consumes only 0.5 to 1.5 kilowatt-hours per kilogram of processed material.

Chemical recycling, due to processes involving heating, distillation, solvent recovery, and polymerization, requires more energy. Consumption is typically 2 to 4 kilowatt-hours per kilogram of processed material—2 to 4 times higher than mechanical recycling. However, if the energy used comes from renewable sources, this gap will narrow.

Chemical management represents another aspect of environmental impact. Mechanical recycling does not produce hazardous chemical waste, but its output has lower value. Conversely, chemical recycling requires meticulous management of solvents and catalysts, but its output materials are of quality equivalent to virgin materials. In calculating environmental benefits, the entire product life cycle must be considered, not just the energy consumed during the process.

Market Segmentation

Choosing the optimal strategy between mechanical and chemical recycling heavily depends on market segmentation. In applications where fiber quality degradation is not critical—such as non-woven textiles used for insulation, geotextiles, and industrial textiles, or low-quality garments—mechanical recycling is preferable due to its economic cost advantage.

However, if superior quality is paramount, chemical recycling should be employed. For example, when recovered fibers are intended for high-durability and performance apparel, technical textiles, or luxury clothing. In these cases, the high quality justifies the higher processing cost.

Based on market segmentation, hybrid approaches have also emerged. In these, pre-processing stages—shredding and carding waste into fibers—are performed mechanically. Subsequently, these mechanically produced fibers undergo chemical processing. This creates an optimal combination of purely mechanical and purely chemical methods in terms of cost and efficiency.

Regulations and Policymaking

New government regulations and policies are increasingly supporting chemical recycling, including Extended Producer Responsibility (EPR) regulations and circular economy frameworks that emphasize the genuine ability for material circularity.

According to European Union regulations, fiber-to-fiber recycling achieved through chemical methods is preferred over downcycling methods. These regulatory preferences can gradually steer economic incentives toward chemical methods, even though their initial costs are significantly higher compared to mechanical methods.

The Outlook for the Textile Recycling Industry

Based on industry forecasts for 2030, approximately 60% of global recycling infrastructure will be mechanical, 35% chemical, and 5% hybrid. This distribution reflects the current dominance of mechanical recycling and its short-term cost advantage, alongside growing chemical recycling capacity to meet premium market segments and circular economy requirements

By 2040, chemical recycling technology will have matured, leading to reduced costs. Consequently, its share in this distribution will increase significantly, as realizing true material circularity becomes an economic necessity.

♦ References

► www.globaltextiletimes.com

♦ Link

► B2n.ir/nassajyar02005

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