bioprocessing for sustainable production of coloured textiles · the stages are highlighted in the...

Work Package 7 – Exploitation and Business Plan

Lead contactor for this deliverable: UNISI Coordinator organisation: University of Siena Coordinator: Rebecca Pogni Dissemination Level: CO Confidential, only for members of the consortium (including the Commission Services)

Bioprocessing for Sustainable Production of Coloured textiles

CIP Eco-innovation – First Application and market replication projects ECO/09/256112/SI2.567273

www.biscol.unisi.it

Starting date: September 1st, 2010 Duration: 36 months

Deliverable 7.4 Intermediate Business Plan on dyeing process

Bioprocessing for Sustainable Production of coloured textile

WP7/Deliverable 7.4 di 21

1. INTRODUCTION AND OBJECTIVES..................................................................................................................... 3 2. SITUATION.................................................................................................................................................................. 3

2.1. TEXTILE PRE-TREATMENT PROCESS ......................................................................................................................... 5 2.2. TEXTILE DYEING PROCESS ..................................................................................................................................... 11

2.2.1. Basic outline of a typical dye production process........................................................................................ 11 2.2.2. Dyeing ........................................................................................................................................................... 12

2.3. ENERGY IN TEXTILE INDUSTRY………………………...……………………………………………………...…..14

3. CONCLUSION ........................................................................................................................................................... 20



1. Introduction and objectives

In the BISCOL project a safer and cleaner process for the dyeing of textiles has been proposed. The

coloration of fibres is a complex phenomenon, which generally consists of swelling of the fibres in

aqueous medium, dye penetration and fixation. Enhancement of these processes requires the

application of a wide range of dyes and auxiliaries, aggressive pH and elevated temperature. Goal

of the BISCOL project is to analyze the complex chain of textile finishing and to propose a

safer and cleaner process to reduce the environmental impact in terms of energy and water

saving.

Considering that the dyeing process shares the market analysis and the industrial context with that

of bio-dyes, it has been presented in Del. 7.3 – Intermediate Business plan on synthesis of bio-dyes

and not repeated in this deliverable.

2. Situation

The textile industry is comprised of a disperse, fragmented group of establishments that produce

and/or process textile-related products (fibre, yarn, fabric) for further processing into apparel, home

furnishings, and industrial goods. Textile establishments receive and prepare fibres; transform fibres

into yarn, thread, or webbing; convert the yarn into fabric or related products; and dye and finish

these materials at various stages of production. The textile chain is thus long and complex.

In its broadest sense, the textile industry includes the production of yarn, fabric, and finished goods.

To characterize the ecological impact related to textile finishing it is therefore of crucial interest to

have a look on the overall textile production chain. The production of textile affords a great variety

of processing steps.

The stages are highlighted in the process flow chart shown in Figure 1 below.



. Figure 1: Typical Textile Processing Flow Chart (EPA Office of Compliance, 1997) The life-cycle of a textile starts from natural fibres or the production of man-made fibres, the next

step is the production of yarns from the natural or synthetic fibres. Fabrics are produced of the

yarns/fibres by different technologies (weaving, knitting, non-woven technologies, braiding,

tufting). Finishing processes (pretreatment, dyeing, printing, and finishing) follows. Some textiles

are coated or laminated. These process steps are not always in the same order. Dyeing, for example

can be carried out on loose fibres, on yarns, on fabrics, and on ready made textiles. The make-up



(cutting, sewing, assembling) is the last step before selling in retail trade or whole trade and

consumer use.

2.1. Textile pre-treatment process A great part of the ecological concerns in the pre-treatment processes in textile finishing mills is

caused by the textile raw materials themselves and textile auxiliaries applied in upstream processing

steps (fibre-, yarn- and fabric-processing).

In pre-treatment steps natural impurities on the textile raw material (greige, grey goods) e.g. by

products on cotton as waxes, proteins etc., vegetable impurities on wool but also by-products from

upstream production steps (preparation agents; sizing agents etc.) and fibre specific by-products

from man-made fibres (monomers, fibre solvents) are removed.

These by-products together with the auxiliaries and chemicals used in pre-treatment cause a

considerable ecological load in the wastewater as well as in the off-gas.

Pre-treatment is a key factor for all downstream finishing steps. Poor pre-treatment generates

quality problems and in consequence re-works and therefore additional ecological loads in the

operations downstream.

Besides the cleaning effect pre-treatment has also an effect on the fibre properties:

- Absorption of dyes and textile auxiliaries increases

- Tensions in textiles are minimized; the dimensional stability is improved.

- Wettability of the material is improved.

- Mercerisation gives a change in crystallinity of the cellulose; the lustre is improved.

Bleaching increases the whiteness of the substrates (important for un-dyed fabrics as well as for

fabrics dyed in light shades or with a high brilliance).

Mechanical, wet, and thermal pre-treatment steps are used (Figure 1). The choice and sequence of

processing steps is substrate specific (cotton, wool, man-made fibres, woven or knitted fabric, etc.),

and depend also on the end-use, downstream processing steps of the textile and the installed

equipment.



Figure 1 – List of the main pre‐treatment processes

1. Mechanical processes

The following mechanical pre-treatment steps are commonly used:

‐ brushing for the removal of impurities

‐ beating (e.g. after singeing or carbonizing) for the removal of impurities

‐ raising (also used in mechanical finishing)

‐ shearing (also used in mechanical finishing).

In comparison to wet and thermal pre-treatment processes mechanical pre-treatment is

accompanied with negligible environmental charges. Besides energy consumption and noise

dust generation should be mentioned

2. Thermal processes

‐ Heat setting (also called thermofixation) is carried out on fabrics made of man-made

fibres or blends of them with natural fibres to relax tensions in the textile resp. fibres

due to upstream fibre/yarn/fabric processing and to improve the dimensional stability

of the textiles. Heat setting is carried out continuously in a stenter at temperatures

between 170 – 220 °C. Heat setting can be done on grey fabrics as a pre-treatment

step, as an intermediate step after dyeing or as a last finishing step (often in

combination with application of finishing auxiliaries).

It has to be taken into account that heat setting of grey fabrics or insufficient pre-

washed textiles can lead to a considerable ecological impact to the off-gas depending

on the amount and type of preparation agents and other fibre inherent ecological

loads (residual fibre solvents, residual fibre monomers). In case of direct heated

stenters Organic-C-load and formaldehyde content in the off-gas.



‐ Singeing is essential when a smooth surface is of interest (esp. as pre-treatment step

before printing processes). The textile passes directly over a flame, metal plate, or

indirectly between heated ceramic devices. Protruding fibres are burned off. Mainly

woven and knitted textiles made of cotton and cotton blends are treated on singeing

machines. Synthetic materials are singed to reduce pilling effects. Sewing yarns are

singed to improve their running characteristics. Of ecological interest are dust and

volatile organic carbon (VOC). Also a relative strong odour emission can be

observed during singeing. Singeing is often combined with a device to extinguish

sparks and a padding device to impregnate the textile directly after singeing with the

desizing liquor.

3. Wet processes

Wet pre-treatment includes various processes. All or only some of these processes may be

required.

The processes can be applied either as separate steps or as combined steps.

In wet pre-treatment batch, semi-continuous, and continuous processes can be used. Fabrics

can be pretreated in open width or rope form. Regarding ecology and economy continuous

pre-treatment operations are to prefer, but batchwise pre-treatment on dyeing machines is

often used in those cases where a great variety of small lots are to be scheduled and handled.

Besides, discontinuous pretreatment is often preferred due to high investment costs for a

continuous equipment.

‐ Desizing is a typical process step in pre-treatment of woven fabrics made of cotton and

cotton blends but also necessary for all grey synthetic materials containing sizes. The

sizing agents on the warp yarns, applied in weaving mills for better weaving efficiency,

have to be removed before further processing in textile finishing. Desizing is done as a

first step in cotton pre-treatment or as a second step after singeing. Water insoluble

sizing agents have to be degraded during desizing; water-soluble sizes can be simply

washed out. The following methods are commonly used (depending on the size type):

o enzymatic desizing processes; starch

o oxidative desizing (e.g. persulfate); all size types

o washing (with/without detergents); water soluble sizing agents.

Desizing can be carried out in a continuous (pad-steam), semi-continuous process or

discontinuous way. As mentioned above, the desizing technology depends on the kind of

size applied on the warp yarn. However, the commission finisher has often no or less



knowlegde on the quantity and type of sizes on the fabrics; for this reason optimization

of the desizing process is not always possible.

‐ To extract natural impurities (waxes, pectines, proteins, metal salts) cotton fabrics and

their blends are treated in a discontinuous or continuous way with hot alkali. The

scouring process can be carried out as separate pre-treatment step or in combination with

bleaching or desizing. Besides alkali (mostly sodium hydroxide) complexing agents and

surfactants are used in the scouring liquor.

Main ecological impact in scouring is caused by non readily biodegradable surfactants

and complexing agents as well as by a high COD-load due to the organic impurities

removed from the fibres. COD-concentrations from 2000 to 6000 mg O2/l are typical.

‐ Bleaching is carried out on natural fibres and man-made fibres. The whiteness of the

material increases and the printing and dyeing processes are improved after bleaching.

During bleaching natural coloured by-products on the fibres are removed resp.

destroyed. Bleaching is carried out for undyed natural materials to achieve extra-white

effects as well as for materials to be coloured with high brilliance or in light shades.

Normally, textiles made of man-made fibres are delivered with a high degree of

whitenesss. However, to achieve extra-white effects (e.g for curtains) bleaching is

commonly used. Bleaching can be carried out on loose fibres, slivers, yarns, and

(mostly) on fabrics in a continuous way or batchwise. The bleaching technologies resp.

the bleaching agents vary with the textile substrate (Table 1).

Table 1 ‐ Bleaching agents for different textile fibres

Textile material/ Bleaching process

Peroxide Sodium Chlorite Reductive

Cellulose fibres + + Cellulose/Polyester + Protein fibres + + Polyester + Polyamide + Polyamide/Wool +* + Polyacrylonitrile + Cellulose ester + Viscose + Elastane + +

* protective agent for polyamide required Peroxide bleaching



In bleaching with hydrogen peroxide the bleaching agent is oxygene, generated from

hydrogen peroxide

under alkaline conditions. It is done at elevated temperatures (60 °C – 98 °C) under

alkaline conditions (pH approx. 12). Main ecological impact to wastewater is caused by

the strong alkali, complexing agents (phosphonates, polycarboxylic acids), wetting

agents, stabilizing agents (esp. sodium silicate), and by-products removed from the

cellulose. COD content in the effluent is in a range between 3000-10000 mg O2/l.

Chlorite bleaching

Bleaching with sodium chlorite is done under acidic conditions (pH 3 – 5) at

temperatures between 70 °C and 95 °C; buffers and sodium nitrate as a corrosion

inhibitor are added. Highly toxic chlorine dioxide can be released in the process, if the

pH is not well controlled. AOX generation through chlorination reactions with organic

compounds has to be minimized by means of a good process control and reduction of

chlorite surplus after bleaching (adding of reducing agents; mostly sulfite).

Reductive bleaching

Reductive bleaching can be carried out with sodium dithionite and sodium formaldehyde

sulfoxylates.

‐ Mercerising (treatment of cotton and cotton blends with strong alkali under tension)

improves the dyestuff absorption and increases tensile strength. A good handle, better

dimensional stability, and a resistant lustre are achieved. Mercerising leads to a change

in the crystalline structure of the cellulose molecules and to a swelling of the fibres.

Woven fabrics are mercerized in full width, knitted fabrics in full width or in rope form.

Normally, mercerising is mostly done with hot sodium hydroxide solution

(concentration varies from 20% - 30%).

‐ Carbonizing is a pre-treatment step for wool (loose fibres and fabrics) with the aim to

destroy and remove vegetable impurities with strong acid.

‐ Felting (shrinkage of textiles made of animal fibres) caused by the unidirectional

oriented scales on the surface of the fibres when animal fibres are mechanical stressed in

wet processes (e.g. dyeing or household-washing) is in most cases an undesirable effect.

In anti-felting operations the scales are minimized with the help of coating polymers,

with oxidizing techniques, or with a combination of these processes, such as Hercosett

process. The Hercosett process (combination of chlorine and polymer (polyamide-

epoxide compound) treatment) is responsible for a relatively high AOX-load in the

effluent.



The possibility to replace the most polluting pre-treatment processes with environmental friendly

technology enabling to ensure good dyeing performances and good dimensional stability for the

treated substrates. Since the target substrates within the BISCOL project are protein and

cellulose fabrics, particular attention will be paid in the anti-felting treatment and in the

enhancement of colour uptake and resistance.

In fact, in the previous review it is clear that surface modification of the fibre is mainly

accomplished by wet chemical processes. An appropriate alternative to its conventional techniques

can be assured by the pre-treatment of textile fibres with atmospheric plasma process. Physico-

chemical method of modifying the surface of polymer substrates without changing the nature of the

bulk of the substrate has been of great interest, particularly in the area of pre-treatment of textiles.

The reason for this interest is the intriguing possibility of modifying polymers and obtaining new

and interesting properties leading to better performance. Conventional wet pre-treatment processes

of textiles are generally energy consuming process. Plasma modification of textiles saves large

quantity of water, chemicals, and electrical energy. Ecological and economical constraints which

are imposed on the textile industry to an increasing extent, call for the development of

environmentally friendly and economic finishing processes. The physico-chemical nature of the

modified fibre surface has a tremendous influence on the following important phenomenon:

‐ Static electricity build up and dissipation.

‐ Moisture transport and comfort.

‐ Oily stain adsorption and release in detergent solution.

‐ Soil deposition, release and redeposition in detergent solutions.

‐ Wettability and adhesion.

‐ Scourability and bleachability of textiles.

‐ Wettability and dyeability

Form the physical point of view, roughening of fibre surface is responsible for changes in the

coefficient of friction, top cohesion, spinnability, yarn strength, etc., as well as for increase in

felting resistance of wool.

For the textile fibres applied within the project the following benefits can be promoted:

WOOL FIBRES

i) increases the top cohesion by a factor of 1.5-2.0; this increased cohesion remains stable after

prolonged storage.



ii) the fatty matter content in wool is removed or reduced by plasma treatment.

iii) considerably reduces the felting potential for any product obtained from the modified wool

iv) increases the mechanical properties of the treated fabric

v) quicker penetration of dyestuffs and chemicals

vi) improves the wettability

COTTON FIBRES

The efficiency of scouring, mercerizing etc. depends on the penetration of water into the fibre and

thus its wettability The wettability of cotton and is increased a few fold due to its pre-treatment.

This phenomenon allow to increase the dyeability of cotton by reducing the required amount of

chemicals and energy.

The main advantages of plasma treatment are the extremely short treatment time and low

application temperatures; water or solvents resp. drying steps after plasma finishing can be avoided.

Chemical and physical modification of surfaces can be achieved with the advantage that no or less

auxiliaries/chemicals have to be added

2.2. Textile dyeing process 2.2.1. Basic outline of a typical dye production process An aromatic ring structure coupled with a side chain is usually required for resonance and thus to

impart colour. (Resonance structures that cause displacement or appearance of absorption bands in

the visible spectrum of light are responsible for colour.) Correlation of chemical structure with

colour has been accomplished in the synthesis of dye using a chromogen-chromophore with

auxochrome. Chromogen is the aromatic structure containing benzene, naphthalene, or anthracene

rings. A chromophore group is a colour giver which form a basis for the chemical classification of

dyes when coupled with the chromogen: azo (–N=N–); carbonyl (=C=O); carbon (=C=C=); carbon-

nitrogen (>C=NH or –CH=N–); nitroso (–NO or N–OH); nitro (–NO2 or =NO–OH); and sulfur

(>C=S, and other carbon-sulfur groups). The chromogen-chromophore structure is often not

sufficient to impart solubility and cause adherence of dye to fiber. The auxochrome or bonding

affinity groups are amine, hydroxyl, carboxyl, and sulfonic groups, or their derivatives. These

auxochromes are important in the use classification of dyes. and softening agents).

As a consequence, synthesis of dye requires the uses of three types of raw materials: chromogen,

chromophore and auxochrome.



Dyes are synthesized in a reactor, filtered, dried, and blended with other additives to produce the

final product. The synthesis step involves reactions such as sulfonation, halogenation, amination,

diazotization, and coupling, followed by separation processes that may include distillation,

precipitation, and crystallization. In general, organic compounds such as naphthalene are reacted

with an acid or an alkali along with an intermediate (such as a nitrating or a sulfonating compound)

and a solvent to form a dye mixture. The dye is then separated from the mixture and purified. On

completion of the manufacture of actual colour, finishing operations, including drying, grinding,

and standardization, are performed; these are important for maintaining consistent product quality.

2.2.2. Dyeing Dyeing operations are used at various stages of production to add colour and intricacy to textiles

and increase product value. Most dyeing is performed either by the finishing division of vertically

integrated textile companies or by specialty dyehouses. The latter guarantee a cheaper product, a

higher quality (mainly due to the fact that this is their only core-business and update their know-

how more frequently and also solve more problems becoming more productive). Textiles are dyed

using a wide rang of dyestuffs, techniques, and equipment. Dyes are sold as powders, granules,

pastes, and liquid dispersions, with concentrations of active ingredients ranging typically from 20 to

80 percent (EPA Office of Compliance, 1997).

Methods of dyeing

Dyeing can be performed using continuous or batch processes. In batch dyeing, a certain amount of

textile substrate, usually 100 to 5000 kilograms, is loaded into a dyeing machine and brought to

equilibrium, or near equilibrium, with a solution containing the dye. Because the dyes have an

affinity for the fibres, the dye molecules leave the dye solution and enter the fibres over a period of

hours, depending on the type of dye and fabric used. Auxiliary chemicals and controlled dyebath

conditions (mainly temperature) accelerate and optimize the action. The dye is fixed in the fibre

using heat and/or chemicals, and the tinted textile substrate is washed to remove unfixed dyes and

chemicals. Common methods of batch, or exhaust, dyeing include beam, beck, jet, and jig

processing. Pad dyeing can be performed by either batch or continuous processes.

Continuous dyeing processes typically consists of dye application, dye fixation with chemicals or

heat, and washing. Dye fixation on the fibre occurs much more rapidly in continuous dyeing than in

batch dyeing.



Each dyeing process requires different amounts of dye per unit of fabric to be dyed. This is

significant since colour and salts in wastewater from spent dyes are often a pollution concern for

textile facilities.

In addition, less dyes used results in energy conservation and chemical savings. The amount of dye

used depends on the dyeclass, the affinity and quality of the yarn, the colourdepth and other factors

(such as quality of the water, salt, auxiliaries…). The dyebath ratio is the ratio of amount of yarn vs.

amount of water in the dyevessel. A dyebath ratio of 1/10 means 1 kg yarn needs 10 litre

water to be dyed (EPA Office of Compliance, 1997).

Principles of dyeing

- Migration of dye molecule from liquor to fibre. This process is assisted by increasing

temperatures and using auxiliaries – substances that help the dyeing process.

- Diffusion of dye from the fibre surface into the fibre. This process is assisted by agitation

of the fibre, dyebath or both together with heat.

- Fixation ensures the dye molecule is attached to the fibre either by physical forces or

chemical bonding. These forces may be weak or strong.

- The unknown or less known variables. As until now no mathematical model exists

by which with certainty the outcome of the process can be predicted and foreseen

industrially.

Most dyeing processes need heat to provide the energy for the dyeing to take place. This is

commonly supplied by direct or indirect steam.

The production of bio-dyes represents the central point of the BISCOL process. The related

business plan is represented by Del. 7.3 where this topic has been specifically addressed.

2.3. Energy in textile Industry

In the world’s new economic system the conditions for keeping the competitiveness have become

quite difficult for establishments. The fast-growing Far East has significantly pulled down the profit

rates of industrial establishments. Both the shrinkage in the market and the decreases in profitability

have forced industrial establishments to effectively manage their costs.



In order to reach this goal, the companies have not only oriented towards qualified human resources

but also have started to pay attention to quality energy supply, which is another fundamental factor

in the sector. Manufacturing loss due to high energy consumption is reflected on the income

statements and balance sheets of these companies, as an increased cost due to inefficient

management of the resources. Particular attention must be paid to implementing energy

conservation measures, specifically in the area of the dyeing and finishing process, where

many small- to medium-sized companies are operating and that is the target of the BISCOL

project. In general, energy in the textile industry is mostly used in the forms of:

- electricity, as a common power source for machinery, cooling and temperature control systems,

lighting, office equipment, etc.;

- oil as a fuel for boilers which generate steam; liquefied petroleum gas; coal; and city gas.

In Table 2 energy consumption shares of two different step of the textile chain have been reported

and it can be seen that energy consumption is relatively high in the fields of dyeing and

finishing, fiber production, spinning, weaving and clothing manufacturing.

Table 2 – Type of energy used in the textile industry.(source UNIDO Japan)

According to that, it is very important to advance energy conservation in the dyeing and finishing

field, which has a high energy consumption share in terms of both the amounts of money and

energy used (up to 13 M kcal).



As it has been extensively reported in the D1.2, the dyeing and finishing process consists of many

interwoven unit operations, and it is well known that the process generally goes through repeated

wet and dry operations. The heat balance of a unit operation can mainly be considered as the

difference between the total supplied heat on the one hand and the sum of the heat required by the

system and various forms of heat losses on the other. This clearly illustrates the importance of the

development and utilization of process- specific techniques, apart from the already-described

management technologies. Table 3 shows that energy saving is a crucial issue in the

implementation of production rationalization.

Table 3 – Relationship between production rationalisation and energy saving

The new dyeing approach (Figure ) that we are developing within the BISCOL project can

induce a direct impact with the reduction of the treatment time and/or reduction in the

process temperature and on the switch of non water-based operation that have been listed as

priorities for an effective energy management.



Figure 2 – Breakdown of the eco‐friendly approach investigated within BISCOL project

More in details, the following benefits are expected by the approach that is under investigation:

‐ Acceleration of process time

The combined use of plasma accelerates processing effects, by using this techniques in pre-

processing.

‐ Reduction of the temperature required to dyeing textile substrate

The set-up of the new surfactant and levelling agents by ACHIMO in combination with

plasma pre-treatment allow to significantly reduce the processing temperature

‐ Reduction of water consumption

Plasma pre-treatment allows to achieve high performances for the treated textile preserving

primary resources such as water.

The preliminary LCA analysis carried out on the new approach performed on woollen fabrics in

comparison with the conventional approach concerning the energetic balance showed that a

significant reduction of the energy required to dyeing 1 kg of textile is achieved: up to 30% of the

total energy can be reduced by applying plasma treatment in combination with the new auxiliaries

set-up by ACHIMO (Table 4). In details, the energy input required for each step of the production

process have been reported. It is interesting to note that even if the Basolan treatment has not

required the implementation of plasma treatment allows to save energy up to 28%! This means

that the influence of plasma treatment is negligible.

Table 4 – Eenrgy consumption in the different step of the BISCOL approach in comparison with conventional dyeing process for woollen textiles.



Conventional Process Plasma + Auxiliary 1 Plasma + Auxiliary 2 Production step Energy

[kJ/kg] Production step Energy

[kJ/kg] Production step Energy

[kJ/kg ] Purge 562.5 Purge 562.5 Purge 562.5 Basolan process 515.6 Plasma 346.5 Plasma 346.5 Dyeing process 13766.6 Dyeing process 11016.6 Dyeing process 8916.6 Purge 562.5 Purge 562.5 Purge 562.5 Drying 1108.8 Drying 1108.8 Purge 1108.8 TOTAL 16516.0 TOTAL 13596.9 TOTAL 11496.9 Considering that the capability of KICO is 1000 t/year of textile and the average share of the

wool fabric is around 15%, the total amount of energy that can be saved by using the new

approach is around 752 GJ/year.

2.4. Water consumption

In average in the EU water consumption is around 32% of water abstraction, since most of

abstracted water is not consumed but returned to the water cycle and made available to further uses,

after proper treatment or natural purification (Figure 3).

Figure 3 – Sectoral water abstraction in Europe

Excluding cooling water, the main industrial water users are the chemical industry, the steel and

metallurgy industries, the pulp and paper industry. Industrial use of water accounts for about 32%

of total water abstractions in the EU. Cooling water represents about 10%, because most of cooling

water is used and not consumed, generally returned to the water cycle.

The textile industry is energy-, water-, and chemical-intensive. Within the industry, the majority of

energy, water, and chemicals consumed is for wet processing. At least 40 litres of water are



required to produce 1 Kilogram of textile, on the average. Typical water demand for the

production of 1 kg of textile for selected fabric type is shown in Table 5.

Table 5 – Distribution of water use in textile processing by fabric type (adapted from US EPA, 1996)

Water use L/kg production Fabric type Minimum Average Maximum Wool 111.0 285.0 658.0 Woven 5.0 113.0 508.0 Knit 20.0 83.0 377.0 Carpet 8.3 47.0 163.0 Stock/Yarn 3.3 100.0 558.0 Nonwoven 2.5 40.0 83.0 Felted fabric 33.0 213.0 933.0 Since textile manufacturing is also a chemically intensive industry and, therefore, the wastewater

from textile processing operations contains processing bath residues from preparation, dyeing,

slashing, and various other operations, textile effluents contain a very diverse range of contaminants

that must be treated prior to disposal.

The analysis of the water availability in Europe depict that the situation of textile industry is under

stress. Even if in the EU15 countries the average WEI was around 21% [EEA, 1999], which is quite

a sustainable index; severe imbalances between regions are observed as shown in Figure 4, 4

countries, in southern Europe representing, are water stressed (Cyprus, Italy, Malta and Spain); 9

countries, lying mainly in southern Europe, which represent 32% of EU population, are moderately

water stressed (Germany, Bulgaria, Denmark, Portugal, Romania, Turkey). Belgium abstracts more

than 40% of its total renewable freshwater resources.



Figure 4 – Water availability around Europe

The picture also compares WEI in 1990 and in 2002 and shows that the WEI has decreased in 17

countries during the period 1990-2002, mostly in the new member states due to the decline of

abstractions (institutional and economic changes), but also in older members, such as Denmark and

Sweden due to the implementation of sustainable water use programmes. Six countries have

increased their WEI – Greece, Luxembourg, Malta, Portugal, Turkey and the UK. If we consider

that Textile industry is located in the Southern countries that are the most severely affected

by water scarcity it is easy to understand the importance of an effective water management in

this manufacturing sector.

As it has been highlighted in the preliminary LCA study, the implementation of the plasma

technology in the production line could allow reducing water consumption up to 20 L per kg

of textile. This means that per year a total reduction of around 3.6 m3/year can be achieved.

Considering that at least 40 L of water in the average is required to treat a textile this is the

amount required to treat up to 300 m of fabric. Moreover, if we consider that by the

application of the eco-friendly auxiliaries a reduction between 10-20% of the pollution load



(in terms of COD) can be reached an additional benefit from the economical point of view can

be achieved.

In fact, according to the table (Table 6) provided us by GIDA (Municipal WWTP in Prato) the costs

for the discharge of the wastewater in the treatment plan is increasing by increasing the COD of the

effluent.

Table 6 – Discharge costs for industrial effluent at the Municipal WWTP in Prato (year 2011)

PARAMETER Price COD [mg/L] BOD5 [mg/L] TSS [mg/L] [€/m3]

500 250 200 0.3131 700 230 150 0.5698 750 250 200 0.6027 1000 330 120 0.7671 1050 350 120 0.8000 1250 350 120 0.9315

Considering that a finishing company has an average COD in between 750 and 1000 mg/L the

reduction of COD in the expected range could allow to reach in the worst case, a reduction up

to 0.15 €. Considering that the total amount of water required to produce 1 kg of coloured

textile with the BISCOL approach is around 60 L, 0.01 € can be saved per kg of treated fabric

meaning at least 15,000 €/year saved.

3. Conclusion

The classical dyeing process is here represented and compared with the BISCOL process. The new

dyeing approach (Figure ) that we are developing within the BISCOL project can induce a direct

impact with the reduction of the treatment time and/or reduction in the process temperature and on

the switch of non water-based operation that have been listed as priorities for an effective energy

management. The first data obtained from the LCA study show that the BISCOL process can give



good results in energy and water saving with a preliminary estimation of saved money per year.

These data are encouraging in view of the final business plan when the evaluable data from the

scale up of the bio-dyes will be available.

bioprocessing for sustainable production of coloured textiles · the stages are highlighted in the...

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