**1.1 Short-staple yarn spinning**

*Textile Industry and Environment*

products they belong in or in different products.

mately 25% of total global fiber production [3].

This should be considered by the producers.

and may be used again in textiles or utilized in other products.

of these waste types can be recycled and utilized as raw materials in same type of

Textile wastes can be divided into two main groups: production wastes and postproduction wastes. Production wastes are basically raw materials of each production step which cannot be put into end product due to different reasons. For yarn spinners, these wastes can occur during cleaning of the fibers or combing out short-staple fibers from the long ones in combing machine, etc. These clean/ unclean wastes in fiber form or not can be reused. After spinning mill, there are wastes in yarn and fabric forms, and they need recycling to be put again in production. Postproduction wastes are generally worn out cloths, which can be recycled

Textiles include different raw material (fiber) types. Fibers used in textiles are categorized into two main groups, which are natural and man-made fibers. Most known examples for natural fibers are cotton (seed fibers), wool, silk (animal fibers), flax (bast fibers), sisal (leaf fibers), and asbestos (mineral fibers). On the other hand, polyester, nylon, acrylic (which are synthetic fibers), modal, viscose rayon, and acetate rayon (which are regenerated fibers) are some of the examples for man-made fibers [2]. Thereby, textile wastes have a great variety of raw material sources. These wastes can be recycled or reused in different products. In 2017, global fiber production exceeded 100 million mt. Polyester has around 51% of total global fiber production. The second most important fiber is cotton, and it has approxi-

Textile wastes can be recycled/reused in textiles or other products. Other product wastes can also be utilized in textile production. One of the most known examples for this is PET bottles. PET bottles are collected, are recycled, and can be used in textile products as "r-PET fiber." r-PET fibers can be used in yarn production, as 100% or in blends, thereby in most of the textile structures. There are various studies about this topic. These studies cover spinning of the fiber, properties of the fiber [4], properties of yarn, and fabric produced from this fiber and all [5]. Some of the researches are focused on using textile wastes in different products. Mishra et al. used textile wastes to produce composites and tested the properties of these composites [6]. Briga-Sa, Binici, and El Wazna used textile wastes as insulation materials, and Briga-Sa indicated that they got results similar to polystyrene (XPS) and mineral wool [7–9]. Shukla used PET fiber wastes to synthesize new chemicals which can be used in different fields [10]. These examples show that textiles are generally sustainable materials. There are too many studies dedicated on

Liquid waste and solid waste are generated during the production of textiles. Especially agriculture of cotton fiber, which is the subject of this study, and the evaluation of the solid wastes that occur during yarn spinning are important for sustainability and environment. These topics are really important for the future, considering the increasing world population and decreasing agricultural areas. Moreover, large amounts of water are consumed; pesticides and synthetic fertilizers are used during cotton growing. Especially pesticides have negative effects on human health. The recycling/reusing of wastes occurring at every stage of textile production will be positive in terms of reducing the environmental effects putting them again in the production chain. Consumers are also becoming more conscious about these effects and they seek environmentally friendly "green products" [11].

Due to increasing fiber production, the amount of pre-consumer and postconsumer textile wastes is increasing. According to a study Pinheiro and de Francisco conducted with Brazilian clothing manufacturers, 167,850 kg of cotton was consumed with these manufacturers, and 19,086 kg of cotton waste occurred in

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this topic.

Spinning is defined by Barker as the "*art of throwing a number of more or less short fibres together in such a way that, being drawn out to form a comparatively fine filament*" [13]. In this process, one of the main defining parameter is fiber length. According to fiber length, machinery and their adjustments that should be used are determined. In textile yarn manufacturing, two main systems are used depending on fiber length: short-staple and long-staple spinning systems. In principle, fibers up to 60 mm in length are spun in short-staple spinning systems, and fibers with lengths over 60 mm are spun in long-staple systems. Short-staple fibers are generally processed dry using mechanical means, and the spinning systems used for this types of fibers are also known as cotton spinning system [14].

From the field, seed cotton moves to gins for separation of lint and seed. This is the first step in which cotton wastes occurred. Cotton gin wastes consist of sticks, leaves, burs, soil particles, mote, cotton lint, and other plant materials [15]. These wastes can be used in different areas such as chemical industry (e.g., soaps), livestock industry (e.g., animal feed), or food industry (e.g., cotton seed oil).

After harvest and ginning, cotton fibers are compressed and bales are formed. For this reason, the first step in a cotton spinning mill is opening. This process is needed in order to clean effectively and form slivers in which individual fibers are oriented very closely to sliver axis [16]. Most of the opening and cleaning is carried out in blowroom machinery. However, card has an important role in opening and cleaning. Most of spinning mill wastes occur in these machinery.

Parallelization is carried out subsequent to opening and cleaning processes. It is really important to force fibers to place as parallel to each other as possible in sliver to spin a good quality yarn. Machine mainly responsible for this process is draw frame which also takes care of attenuation and doubling of slivers. Fibrous waste amount of these machines is lower compared to the rest of the spinning mill machinery.

To produce some cotton end products especially in which fine yarns are used, yarns with better properties are needed. One of the ways to do so is to remove some fibers that are much shorter than the mean of the distribution from slivers [16]. This process is carried out with combing machine. In **Figure 1**, spinning machinery line with combing machine is given. Cotton fibers longer than 27 mm are generally used after combing up to 13% which is sufficient for good quality yarns [16]. This means waste ratio of this process is high.

During roving and spinning (for ring spinning), some fibers cannot enter yarn or roving body, and fiber fly is formed. These fibers are sucked by pneumatic systems that are placed after delivery rollers, and they are collected in the machine. Moreover, if end breaks happen in yarn or roving, the same system collects flowing fibers after leaving delivery rollers till operator's intervention. In open-end rotor spinning systems wastes can occur in opening rollers which also are responsible for cleaning.

**Figure 1.** *Opening and cleaning lines of combed ring spinning [17, 18].*
