10: Recycling

10.1 Introduction, terms and definition

10.1.1 Introduction

The textiles and apparel industry is one of the largest and fastest growing global industrial sectors,

owing to increasing population, the rise in consumption, the diverse applications of textiles, and

greater productivity in mass production processes.

As a resource and energy intensive industry, the apparel sector’s presence is far-reaching with

associated environmental, economic, and social impacts across the value chain.

The textiles and apparel industry is one of the largest and fastest growing global industrial sectors,

owing to increasing population, the rise in consumption, the diverse applications of textiles, and

greater productivity in mass production processes.

As a resource and energy intensive industry, the apparel sector’s presence is far-reaching with

associated environmental, economic, and social impacts across the value chain. The ecological

footprint of the industry, specifically the impacts of textile and associated chemical waste, remains

as both a continuing global challenge and an opportunity to drive innovative change in processes,

products, and sustainable development for the future.

Across the industry, there is increasing awareness of the global impacts of the current linear system

of take-make-dispose. This extends from raw materials extraction and production inputs, to

distribution and usage, and results in large volumes of generated waste, degradation of the

environment, ecosystems, and overall, uncaptured economic opportunities. In recent decades

there has been a growing push for calls to action among stakeholders and policy makers, which

have led to and continue to drive developments in improved practices and innovative technology.

The overarching intention is to shift from a linear to a regenerative circular system in which

products and material usage are kept and maintained within closed-loop cycles and associated

waste, energy, and emissions are minimized and gradually designed out.3 Such practices extend

from resource extraction and material production through to business models, design principles,

and consumer perception and engagement.

Addressing the environmental challenges faced by the apparel industry from a material resources

standpoint entails materials and process technology developments and advancements at all stages,

from raw materials production to managing and designing out waste streams. With a reported 87%

of all end-of-use textiles going to landfill and incineration, textile waste has become a growing

global challenge and concern. Textile recycling technology is a key enabler in transitioning to a

circular system, specifically with the establishment of fibre-to-fibre streams. In addition to this,

consideration of the impacts associated with chemicals from the dyeing and finishing processes

used to make textiles for clothing must be addressed. Post-production waste management and

clothing usage and disposal have resulted in contamination of major waterways, notably from

manufacturing waste in the countries where production takes place, or post-consumer waste in

landfills. Dye and finishing chemicals have also been cited as having the potential to impede textile

recycling methods.

10.1.2 Textile recycling

Textile industry is among the most essential consumer goods industry. We all need garments and

other textile products such as footwear and bags etc. However, textile industry is also accused of

being one of the most polluting industries. Not only production but consumption of textiles also

produces waste. To counter the problem, textile industry has taken many measures for reducing

its negative contribution towards environment. One of such measures is textile recycling- the

reuse as well as reproduction of fibers from textile waste.

10.1.3 Why textile recycling?

Textile industry is among the most essential consumer goods industry. We all need garments and

other textile products such as footwear and bags etc. However, textile industry is also accused of

being one of the most polluting industries. Not only production but consumption of textiles also

produces waste. To counter the problem, textile industry has taken many measures for reducing

its negative contribution towards environment. One of such measures is textile recycling- the

reuse as well as reproduction of fibers from textile waste.

Waste

10.1.4 WHAT IS A WASTE?

Waste is an unwanted or undesired material or substance, it is also referred to as rubbish, trash,

garbage, or junk depending upon the type of material and the regional terminology. This could

be explained easily with the following diagram

Raw Materials Production

The raw materials in various combinations undergo different processes during production and are

converted to finished goods. The trash left out after each process during production remains

waste.

10.1.5 Reasons for Wastage

• In Efficient, obsolete and conventional technologies

• Lack of technical skills

• Lack of awareness in terms of quality

• Thus by training the employees about the technologies that are

• upgrade and motivating those to manage Waste would be more effective as well everlasting.

10.1.6 Why should we manage waste?

Population increase and high consumption of products in the developed world has created a

global waste problem. Affluence has created effluence –the more we have to dispose of

safely. Scientists now believe we are producing more waste than the environment can absorb.

The benefits of managing waste include:

Saving resources and energy, Reducing pollution, and Increasing the efficiency of production.

Fig 10.1 Flow Chart Of waste

Finished Product

10.1.7 How to Reduce Waste?

According to Waste Minimization Guide, “Most of the organization is taking the costs as a

labour cost or manufacturing cost or wherever they like it to be. These costs can be controlled

and managed once they are identified and analysed. The only source to get a better profit

out of minimization cost is effective control over the waste during production in

industries which would bring money back within a short span of time apart from tremendous

improvement”

According to Waste Minimization and Total Productivity Maintenance Guide “By effective total

productivity maintenance, waste could be at the most minimized in the industries as the

employee efficiency is increased. For this, a corporate culture should be built up within

the employees. The implementation of Total Productivity Maintenance can generate

considerable cost saving, preventive culture through increased productivity and participation.

It could be achieved by, Reducing material waste at source means greater resource efficiency,

less pollution and more profit.

If you consider the cost of materials, treatment, energy and wasted labour, the real cost

of waste can be 5-20 times the costs of its disposal.

Reductions in waste go straight to the bottom line, as raw materials often account for a

significant amount of turnover.

Typical waste reduction projects have payback periods of months, not years

Make a flow chart of material and waste flows and try to put numbers on it for

amounts and cost.

Employees are motivated by feedback about a company‟s waste reduction programme

Report waste as a percentage of production-it‟s a good way of monitoring progress over time.

Waste minimization can be defined as “Systematically reducing waste at source”.It means:

• Prevention and reduction of waste generated

• Efficient use of raw materials and packaging

• Efficient use of fuel, electricity and water

• Improving the quality of waste generated to facilitate recycling

• Encouraging re-use, recycling and recovery.

10.2 Sources of textile Wastage

Textile waste streams comprise pre-consumer (or post-industrial) waste, and post-consumer

waste. Pre-consumer waste includes materials arising from industrial and commercial processing

of textiles or manufacturing of garments (scraps, excess inventory, damaged or defective

materials, samples). Post-consumer waste includes end-use of products, such as recalled

inventory, items returned or disposed of by the consumer. Figure 4 depicts general material and

common chemical waste streams during apparel manufacturing and use.

Figure 10.2: Different type of waste

10.2.1 Textile Fibers

Global fiber production in 2016 was estimated to be 94.5 million tonnes, dominated by synthetic

fibres (68.3%) –predominantly polyester (64%) estimated at 64.8 million tonnes, followed by

cotton (22%), man-made cellulosics (6%), and animal-based fibres (1.5%- 80% wool, 20% down)

(Figure 3).18 Synthetic fibres comprise production from organic compounds derived from non-

renewable sources (petroleum), and inorganic-based materials (ceramics and glass).8 Natural

Figure 10.3: Global fiber production in 2016.

fibres are derived from plants (cellulosics), animal proteins (wool, silk), or minerals (asbestos).8

In this report, four major materials of focus identified based on the synthetics and naturals

include: polyester, nylon, cotton, and wool.

10.2.2 Spinning waste

Cotton fiber bale contains a lot of wastages such as foreign particles, dust, seeds, short fibers etc.

and so when processed through different sections of a spinning mill then different types of

wastage produced in different sections. The wastage % in blow room is 3% and blow room waste

is called lap waste. Carding section wastage % is about 10%. The wastages of carding section are

called dropping-1, dropping-2 and sliver waste. The wastage % in draw frame section is about

0.5%. The wastage of this section is called sliver waste. The wastage % in comber section is

about 14-15% and the wastages are called noils, lap and vacuum waste. The % of wastage in

simplex section is about 0.5% and the wastages are called roving and sliver wastage. The

wastage % of ring frame is 2-2.5% and the wastages are called pneumafil, hard waste, vacuum

waste etc.

Figure 10.4: Wastes from different sections of spinning factory

10.2.3 Weaving waste

Like spinning mills different types of wastages found in weaving mills also. Now we will know

about it.

Figure 10.5: Wastes from different section of a weaving factory

Residual yarns which are left on the cones after warping are considered as wastages. In the

warping creel section it is not possible to empty all the cones and there will always be a little

amount of yarn left on the cones. Sizing waste is another kind of waste in a weaving factory.

When in the weavers beam section a new set of warp yarn is started then it is necessary to

eliminate some portions of the yarns to ensure that properly sized yarns are wounded on the

weavers beam. After sizing wastage, comes the knotting wastage. Knotting is done to ensure all

the warp ends of two beams are available for attaching together. Beam residual wastage is

another kind of weaving wastage. When a weaver beam is finished, a small amount of warp yarn

remains unused on the weavers beam and it is not possible to finish yet. Auxiliary selvage

wastage is also a common weaving wastage. Auxiliary selvage is a fake selvage used to hold the

weft yarn during loom beat up period.

10.2.4 Knitting waste

Knitting has a glorious history. Knitting can be done on machine or by hand. There are various

types of knitting styles and methods. If any fault occurs in the knitting process or any fault in the

raw materials there will be knitting wastage. Now we will know about the different types of

knitting wastage.

Figure 10.6: Wastes found in a knitting factory

When a new order is created the merchandiser makes sample first. To make sample, trials run in

the knitting machine. Due to trials knitting wastage generated. In knitting floor wastage may

occur due to yarn. If the cone is faulty or the yarn is faulty then wastage may generate. Fly

generation from different yarn guides also cause knitting wastage. There are various types of

knitted fabric faults like barriness, spirality, thick and thin place, holes, slubs, sinker marks,

stains, stripes etc. Due to these fabric faults knitting wastage generated. Besides due to wrong

knitting program, knitting wastage generated.

10.2.5 Dyeing waste

Textile dyeing factories are the most common factories to generate waste water which is a great

threat for our environment. Many machine manufacturing companies are trying to introduce new

technologies to reduce waste water. Some are trying to develop waterless dyeing methods.

Figure 10.8: Dyeing factory waste

Besides, there are various types of dyeing faults. Due to different types of dyeing faults,

wastages generated. The most common dyeing faults are uneven dyeing, batch to batch shade

variation, crease marks, selvage to selvage shade variation for denim, metamerism etc. Due to

these faults wastage generated in the dyeing floor.

10.2.6 Clothing waste

In a clothing industry there are different types of sections like cutting, bundling & shorting,

sewing, printing, embroidery, finishing. In every section wastages produce. Cutting section is the

main section to produce wastage in a clothing factory. Due to several roles and marker

utilization, a huge amount of wastages produce in the cutting section. After cutting all the body

parts are inspected and then shorted and bundled. For this reason some faulty pieces may remain

in this section as wastage. Then the loaders take these bundled pieces and distribute in the

sewing section. In the sewing section if a worker finds any faulty piece, he rejects it. Due to this

reason wastage generated in the sewing section. In the printing section if any print doesn’t match

with the standard, the garment piece will be a waste. In the embroidery section, if the embroidery

is not done on the proper place, the garment will be treated as wastage. In the finishing section if

there is measurement defect, trims or press defect there will generate wastage.

Figure 10.8: Clothing wastes

10.2.7 Consumer waste

Figure 10.9: Consumer wastes

Global clothing production has been doubled from the last decade. The average lifetime of a

garment product is approximately 3 years. The average person buys 50% more items of clothing

every year and keeps them for about half as long as 15 years ago which generating a huge

amount of textile waste.

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10.3 Textile recycling process

Textile recycling processes have long existed, but have been greatly influenced by factors such as

high prices, volume, and availability of virgin raw materials, which have limited the ability to be

integrated as established and economically viable operations.6 Processes such as re-spinning of

post-industrial and post-consumer materials, pulping of cotton and linen, and non-woven material

production have existed for centuries, with variations of such operations currently practiced.6

In recent times, there has been great interest in increasing the reuse and recycling of textiles,

notably further developing textile recycling processes, because of an increased awareness of the

impacts of the existing linear supply chain of the apparel industry. Reuse refers to the utilization

of product in its original form, and recycling refers to the conversion of waste into product.21

Recovery of materials and energy, specifically through the application of recycling technologies

offer potential for greater value creation within the textiles economy, and would greatly contribute

to the vision of a circular economy model proposed by the Ellen McArthur Foundation –a

restorative, regenerative, and distributive system by design, in which value is circulated among

stakeholders, from producers to consumers in the system.

Four categories of recycling technologies exist and include, primary, secondary, and quaternary

approaches, summarized as follows:

Primary: recycling material in its original form for recovery of equal value

Secondary: processing post-consumer product usually by mechanical means into product with

different physical and/or chemical properties (mechanical recycling)

Tertiary: processes such as pyrolysis and hydrolysis, in which waste is converted to basic chemical

constituents, monomers, or fuels (chemical recycling)

Quaternary (recovery): waste-to-energy conversion processes such as incineration of solid waste,

or utilization of heat generated ii

Figure 10.9: Different recycling methods

10.3.1 Textile Fiber Production and Recycling

Textile fiber recycling of polyester, nylon, cotton and wool are discussed in this section, with a

general focus on fiber-to-fiber (f2f) recycling, and overview of technologies for fiber blend

recycling

10.3.2 Polyester

Polyester accounts for most of synthetic fibers produced globally (64%, 2016), and is the most widely consumed

fiber. Polyethylene terephthalate or PET is the most common subclass. The raw material components of PET are

generally derived from petrochemicals, with main applications for fiber and packaging production, and a small

proportion for film applications (Figure 9). Polyester is characterized by its strength, crease-resistance, and lower

water uptake (dries quickly). The environmental impacts of polyester are significant, with recent studies of micro

plastic release in aquatic systems which have characterized and reported the presence of substantial amounts of

polyester (majority) among synthetic microfibers and particles collected from wastewater treatment facilities.

Polyester is produced by condensing monoethylene glycol (MEG) and purified terephthalic acid (PTA) or dimethyl

terephthalate (DMT). To form fibers, PET pellets are heated, forming fibers and melt-spun into filament yarns. Yarns

may be texturized to resemble cotton or wool yarns.29 To form fabrics, yarns are knit or woven. Approximately 7%

of total polyester fiber production is derived from recycled polyester materials.

Figure 10.10: Virgin polyester production methods. Modified and reproduced from [30,31].

10.3.3 Polyester Recovery and Recycling

The grades of PET polymers differ in terms of physical properties, which ultimately affect recycling, and designates

the intended applications.

10.3.4 Mechanical Recycling

Mechanical recycling of polyester consists of a re-melt process (or melt recycling). The process consists of the

following main steps:

-Collection, sorting, separation, and removal of contaminants or non-target materials

-Reduction of size – crushing, grinding, shredding, or pulling

-Heating/re-melting, and extrusion into resin pellets

-Melt extrusion into fibers

-Processing of fibers to fabric

Figure 10.11: General route for mechanical recycling of polyester.

The PET recovered from mechanical recycling is often used in lower value applications, due to the loss of physical

properties, degradation, and contamination during use cycles and processing. Post-consumer PET bottles (generally

higher IV value) are most often recycled into PET yarns (lower IV values) and are a successful example of open-

loop recycling. From 2015, the market of recycled PET spun into yarns from plastic bottles, apparel materials

increased by 58%. The reverse process is not commonly practiced, due to low prices and high production capacity

for virgin PET resin, thereby resulting in a very low incentive to invest in technology to upgrade lower IV materials

to meet higher value specifications. Polyester from post-industrial waste or post- consumer PET bottles most often

undergo fiber-to-fiber mechanical recycling, and ease in recycling by this route is due to the waste material

properties being relatively close to 100% PET. However, maintaining quality of respun polyester is a challenge in

mechanical recycling, along with decolourization and loss of mechanical properties, as cheaper recycled polyester

materials are known to have yellowing problems when respun from mechanical recycling routes. Varied material

composition or contamination from post-consumer textile waste would be more difficult to mechanically recycle

back into polyester fiber.

Other options for the mechanical recycling of pre-consumer and post-consumer PET textile waste generally include

end uses for filler materials or nonwoven materials, for furniture, mattresses, insulation, or automotive lining.

10.3.5 Chemical Recycling

Chemical recycling pathways for PET have been demonstrated and include processes which

break down (depolymerize) the polymer into its components (monomers, oligomers, other

intermediates). Various end products may be formed based on the chosen process and

depolymerization additives. Chemical treatment in the recycling process may also facilitate the

separation of PET from other materials, such as blended fibers (i.e. elastane or cotton), or dyes

and chemical finishing, as well as the creation of other end products of equal value. For fiber-

to-fiber recycling, the desired end products to reproduce virgin quality PET resin are the main

monomer constituents of PET: ethylene glycol and purified terephthalic acid (PTA) or dimethyl

terephthalate (DMT). The most common depolymerization methods include: hydrolysis,

methanolysis, glycolysis, or hybrid routes.

Figure 10.11: Overview of different approaches for chemical recycling of polyester (monomer

products repolymerized to polyester). Modified and reproduced from.

Obstacles to the practical application for polyester chemical recycling include blended fabrics

(i.e cotton, elastane blends); the use of polymers, dyes, additives, and processing agents in

textile materials. Difficulties in separating such substances may result in significant degradation

of the polyester during the recycling processes applied or require the application of a more

advanced process for their removal. Other issues have included economic feasibility compared

to the cost of producing virgin fiber, and environmental impacts of applying new chemical

processes to recycle polyester fibers.

Figure 10.12: Recycling process at different manufacturing segment

10.3.6 Reducing Water Use

Chemicals Consumption

Cost savings through improved process efficiency, waste minimization and reduced water and

chemical use can all be achieved by the better control of resources. Once the audit has been

completed, there should be a good idea of the quantities of water and chemicals used where and

how they are used, and the effects of their use in terms of effluent flows and costs. The

company is therefore in a position to consider whether it is possible to reduce usage and save

money.

Options For Reducing Water Use

This Section outlines a range of options for reducing water use. However, because of the

complex nature of the textile industry, not all of these options will be applicable to every textile

company. The examples given illustrate the actions that have been taken to reduce water use by

various companies in the UK and abroad. They show that, where water conservation has not

been considered before, it is not unusual to achieve reductions of 20 - 50%.

Ø Simple water-reducing options

• Repair leaks, faulty valves etc.

Establish maintenance checklists and set priorities for repair, depending on the severity of the

fault. Remember that small, constant leaks may look insignificant but the associated water loss

can be substantial, especially if multiplied over a whole site. Remember, too, that leaks

continue for 24hours/day, seven days/week.

• Turn off running taps and hoses

This simple procedure can result in substantial savings. People are often unaware of the cost of

leaving taps and hoses running. They are more likely to turn off running taps and hoses if they

are made aware of the annual cost of waste. Meanwhile, fixing hand triggers to hoses is a

simple way of reducing water use and saving money.

• Turn off water when machines are not operating

Make sure operators turn off machines during breaks and periods when production is low, and

also at the end of the day. Avoid circulating cooling water when machines are not operating.

This will save both water and energy. Employees at a small hat-dyeing company often left

hoses running after hats had been cooled as part of the manufacturing process. By attaching

hand triggers to the hoses, water and effluent costs have been reduced by around £2 000/year.

Dye-house employees have been known to leave a tap running in summer to keep drinks cool.

A half-inch diameter pipe running for ten hours a day at full bore could cost £2 500 a year in

water and effluent charges. It would be much cheaper to buy a refrigerator!

Ø Advanced water-reducing options

• Reduce the number of process steps

With the continual improvements in chemical performance, processes should be regularly

reviewed to ensure every stage is still necessary. Many firms have dramatically reduced rinse

water by reducing the number of process steps involved.

• Reduce process water use

Washing and rinsing are both important for reducing impurity levels in the fabric to pre-

determined levels. Because water and effluent disposal costs have been low, there has been a

tendency to overuse water. Now that prices are increasing, the optimization of water use could

pay dividends. One possible option is to reduce rinse water use for lighter shades. Table 4 gives

examples of successful water reduction projects in batch and continuous operations.

Ø Dyeing operations Winch dyeing

By dropping the dye batch and avoiding overflow rinsing, water consumption was reduced by

25%.

High and low

By replacing the overflow with pressure-jet dyeing batch wise rinsing, water consumption was

cut by approximately 50%.

Beam dyeing

Preventing overflow during soaking and rinsing can reduce water consumption by about 60%.

Automatic controls proved to be economical, with a payback period of about four months.

Jig dyeing

Reductions in water consumption ranging from 15% to 79% were possible by switching from

overflow to stepwise rinsing. Rinsing using a spray technique, which was tried on a laboratory

scale, was also effective.

Cheese dyeing

A reduction in water consumption of around 70% proved possible with intermittent rinsing.

Continuous dyeing

A 20 - 30% saving was realized by introducing automatic water stops. An effective method of

washing is to use a countercurrent system. Horizontal washing equipment delivered double the

performance of vertical washing machines, using the same amount of water.

Ø Examples of process water reduction

Instead of softening as the final rinse, a Leicester-based dyer softens its cloth outside the batch

process by pad applications. This reduces the number of process steps, saves on water and

reduces process time by one hour. Apart from the saving in water, chemicals, energy and

effluent, more fabric can be processed in a shift.

A medical textile company in Lancashire has cut two wash cycles from its bleaching process,

reducing effluent costs by £1 700. There have been associated savings in water, chemicals,

energy and time.

Recycle cooling water

Many cooling water systems are operated on a once-through basis. The resulting hot water is

generally uncontaminated and can be re-used in the process as make-up or rinse water.

Re-use process water

It is sometimes possible to re-use certain waste streams, e.g dilute wash water, in other parts of

the process:

• Process water in other textile operations, with or without the addition of chemicals.

• Rinse water for another process in which low-grade rinse water is acceptable.

• Rinse water for direct use in a continuous countercurrent washing system where dilute

rinses are re-used in successively dirtier washing bowls.

Other options for process water re-use include:

• Using scouring rinse waters for desizing or machine cleaning (this option requires

additional tank storage, but such storage may be available where there is unused

equipment).

• Using mercerizing water to prepare baths for scouring, bleaching and wetting fabric (in this

option the caustic content of the liquor must be continuously measured).

• As water and effluent costs continue to rise, new technologies for treating and recycling

water for process use are more likely to become viable.

Countercurrent washing/rinsing

Countercurrent washing/rinsing is an established technique common on continuous ranges. This

system of operation can significantly reduce water use.

Ø Options For Reducing Chemical Use

Most of the chemicals used in textile processing are not retained on the fiber but are washed off.

Effluent strength - and therefore treatment costs - can be reduced by: Controlling the quantity of

each chemical used;

Replacing more-polluting chemicals with less-polluting substances. The options chosen will

vary from company to company.

ü Simple options for chemical reduction

Recipe optimization

The chemical recipes used in wet processing are often fail-safe under the most extreme

conditions.

This results in the overuse of chemicals and increased effluent strength. Check whether the

recipes are mixed to specification and whether the chemical is vital to the process.

Dosing control

If recipes are mixed manually, check how operators measure and control dosing. If automatic

dosing systems are used, check whether they are properly calibrated. Overuse will result in a

higher strength effluent and will increase effluent disposal costs. Unnecessary chemical use also

increases chemical costs.

ü Identifying Opportunities for reducing Chemical Use

In some cases it is possible to achieve a 20 - 50% chemical reduction by reviewing recipes and

chemical use. This can correspondingly reduce effluent BOD by 30 - 50% and cut the costs of

effluent disposal.

Instrumentation

Most textile processes take place under high temperature (90°C+) and/or pressure conditions

over a considerable period of time. Check that these conditions are optimized for each batch or

production. In many cases, instruments can be installed to ensure uniformity of conditions. If

instruments of this type are installed, make sure that they are calibrated and show the true

conditions.

Pre-screen chemicals

Chemical data relating to the strength (BOD, COD) and toxicity (metals content, etc.) of

chemicals are available from manufacturers and suppliers in the form of Material Safety Data

Sheets (MSDS).

These should contain chemical, eco toxicological and environmental information and will help

to prescreen chemicals and select those with the least effect on effluent strength and toxicity.

Chemicals such as alkyl phenol ethoxylates (APEs) may be present in detergents and are of

continuing concern because of their oestrogenic effect on fish.

Pre-screen raw materials

Raw textile fibers can contain a number of toxic substances, which end up in the effluent after

processing. Where possible, select raw materials from countries that have banned the use of

toxic chemicals. The International Wool Secretariat (IWS) has recently carried out an

investigation for wool processors and stock yarn dyers for the carpet industry. Now, by

purchasing their wool fleece from carefully selected locations, processors have reduced toxic

substances in their effluent.

Production scheduling

The need for machine cleaning between dye and print runs can be dramatically reduced by

careful production scheduling. By progressing from lighter shades of dye to darker shades (and

back again). Some companies have eliminated many of the cleaning cycles, cut down on dye

losses and reduced effluent quantities.

ü Advanced options for chemical reduction

• Product Fiber Dye Machine

• Knit fabric Polyester Disperse Jet

• Cotton Reactive or direct Beck

• Poly/cotton Disperse/reactive or direct Beck

• Yarn package Polyester Disperse Package

• Poly/cotton Disperse/reactive or direct Package

• Hosiery Nylon/Spandex® Acid Paddle

• Hosiery Nylon/Spandex® Disperse/acid Rotary drum

• Carpet Nylon Disperse/acid Beck

• Polyester Disperse Beck

• Woven fabric Aramid® Basic Jet

• Skein/hank Acrylic Basic Skein/hank

Ø Examples of dye bath re-use Improved dye fixation

Considerable attention has been given to maximizing the fixation of dyes to yarn and fabric,

and new techniques are continually being developed. Better fixation contributes to lower

chemical use and lower effluent contamination. Textile managers should regularly monitor

specific dye consumption to ensure that optimum performance is maintained.

Effluent treatment

Some companies have to correct the pH of their final effluent to sewer by dosing with acid or

alkali. Examine the range of waste streams available and consider neutralizing one stream with

another, thereby eliminating the need for additional chemicals.

Specific benefits of new printing equipment include:

Reduced cleaning loss - In rotary screen printing, up to 8.5 kg of color or print paste can be

present in the pipe between the dye tank and squeegee blade. This will be ‘lost’ when the pipe is

cleaned out at changeover. Reduced-diameter pipework and reverse compressed air injection

have reduced this loss to just 1.5 kg.

Screen printing squeegee wash – Wash water use for squeegee cleaning can be reduced from

100 liters to 20 liters per squeegee by replacing manual washing with automatic high pressure

water cleaning.

Conveyor belt wash water recycling - Older machines use substantial quantities of water to

remove lint and dye from the print machine conveyor in a blanket wash at the end of the line.

New equipment uses staged rinsing with countercurrent rinse water flow, significantly reducing

water use and effluent generation.

Other technological developments include:

A new system of package dyeing has been developed for dyeing very soft yarn packages, eg

delicate wool, polyamide carpet yarns, acrylic and wool yarns. The system can replace hank

dyeing of these fibers. Cost savings are achieved by reduced fiber wastage, omitting handling

operations, shorter cycle times and reduced water use.

Cleaner technology

• Single-stage desizing-scouring-bleaching processes for processing cellulosic and their

blends with synthetics.

• Solvent-aided scouring and bleaching processes.

• Activated peroxide bleaching taking chemically-treated goods straight into a peroxide bath

through the washing machine.

• Dyeing-sizing of warp yarns for denim-style products.

• Hot mercerisation in place of conventional cold mercerization, often enabling the

elimination of separate scouring treatment.

• Combined disperse and reactive/direct color-dyeing of blended fabrics containing low

percentages of cellulosics.

• Use of padding method in place of exhaust methods for dyeing, wherever possible.

• Use of bicarbonate in a peroxide bath for vat oxidation to convert caustic alkalinity into

carbonate alkalinity for its easier removal. Alkalinity requires a plentiful supply of water.

• Electrolytic process for the dyeing of vat colors and reduction-clearing of disperse color

printed synthetic fabrics.

• Dry-heat fixation techniques for the development of Rapidogen prints in place of the

conventional acid- steaming method.

• Direct finishing of pigment-printed goods and direct carbonizing of disperse-printed goods

without intermediate washing

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