Biovision in Textile Wet Processing Industry- Technological Challenges

Volume 7, Issue 1, Spring 2011

C. Vigneswaranb, N. Anbumania and M. Ananthasubramanianc aDepartment of Textile Technology, bDepartment of Fashion Technology and cDepartment of Biotechnology PSG College of Technology Coimbatore – 641 004, India

ABSTRACT

Environmental consciousness is one of the major concerns for textile wet processing industry as the industry contributes much to industrial pollution problems facing the country. Such pollutants as such as lime, sodium sulfide, salt, solvents, synthetic pigments come mainly from desizing, scouring, bleaching and dyeing processes in textile wet processing. In order to overcome the hazards caused by the chemical effluents, use of enzymes as a viable alternative has been resorted to in preparatory dyeing operations such as desizing, scouring, and bleaching treatments. This review focuses on the use of microbial enzymes as an alternate technology to the conventional methods, and highlights the importance of these enzymes in minimizing the pollution load. Environmental pollution has been a major irritant to industrial development. Also in this paper we have discussed the advantages and limitations of bioprocessing techniques in the various textile wet processing such as desizing, scouring, bleaching, biopolishing, bio-singeing and bio-decoloration in the dyeing effluents for cellulosic and non-cellulosic materials.

Keywords: enzymes, dyeing, wet processing, environmental pollution

1. INTRODUCTION also necessary to get optimum results. In the conventional textile wet Chemical and chemical-based industries are processing, the grey fabric has to undergo a the prime targets of the environmentalists series of chemical treatments before it turns for their crusade against pollution, and into a finished fabric. This includes desizing, textile industry has also not been left out of scouring, mercerization, bleaching and the reckoning. The generation of pollution is washing. For all these steps, the chemicals significantly high in the preparatory and used are quite toxic. During fabric dyeing operations compared to the post manufacture, the non-cellulosic and foreign dyeing operations. In fact, one third of the constituents are removed partially or pollution caused by the textile industries completely in the various pre and post results from the wastes generated during operations; the extent of removal of these desizing operations. The wastes from the constituents decides the characteristics of dyeing houses are let out into the drains the final textile fabric [1]. Besides chemical which in turn empty into the main sewerage treatment, certain enzymatic treatments are causing hazard to those who use this water.

Article Designation: Scholarly 1 JTATM Volume 7, Issue 1, Spring 2011

Many dyeing houses have been forced to Various applications which entail enzyme close down because of their noncompliance and colors broadly included fading of denim with the standards laid down. In a short span and non-denim, bioscouring, bio-polishing, of time, Indian textile industry has faced silk degumming, carbonizing of wool, serious challenges such as German ban on peroxide removal, washing of reactive dyes, pentachlorophenate, certain azo dyes, etc. formaldehyde, etc. on one hand, and court order for compliance with environmental 2.1 BIOTECHNOLOGY IN TEXTILE regulations. The attention of dyeing units is PROCESSING focused towards revamping the processing methods, recovery systems, and effluent The major areas of applications of treatment techniques to make textile biotechnology in textile industry are: processing eco-friendly. Intensive efforts are  Improvement of plant varieties used being directed towards using a viable in production of textile fibers. alternative technology for pre and post  Improvement of fibers derived from processes using enzymes. This could be one animals and health care of animals. of the ways of solving the industrial  Novel fibers from biopolymers and pollution problems resulting from textile genetically modified waste water effluents and sustainable planet. microorganisms.  Replacement of harsh and energy 2. BIOPROCESSING demanding chemical treatments by environment friendly routes to Bioprocessing can simply be defined textile auxiliaries such as dyestuffs. as the application of living organisms and  Novel uses for enzymes in textile their components to industrial products and finishing. processes. It is not an industry in itself, but  Development of low energy enzyme an important technology that will have a based detergents. large impact on many industrial sectors in  New diagnostic tools for detection the future. Bioprocessing is the application for adulteration and quality control of biological organisms, systems or of textiles. processes to manufacturing industries.  Waste management. Bioprocessing firms will rely mainly on inexpensive substrates for biosynthesis, 2.2 ENZYMES IN BIOPROCESSING processes that will function at low temperatures, and will consume little energy Today, enzymes have become an [2]. In Textile Processing, the enzymatic integral part of the textile processing. removal of starch sizes from woven fabrics Though enzyme in desizing application was has been in use for most of this century and established decades ago, only in recent years the fermentation vat is probably the oldest the application has widened with new known dyeing process. Bioprocessing a new products introduced. With the increase in impetus in the last few years has been the awareness and regulation about environment very rapid developments in genetic concerns, enzymes are the obvious choice manipulation techniques which introduce the because enzymes are biodegradable and they possibility of „tailoring‟ organisms in order work under mild conditions saving the to optimize the production of established or precious energy [4]. Enzymes being novel metabolites of commercial importance biocatalysts and very specific are used in and of transferring genetic material from one small amounts and have a direct organism to another. Bioprocessing also consequence of lesser packing material used, offers the potential for new industrial the transportation impact is lower. In an processes that require less energy and are overall consideration enzymes are the based on renewable raw materials [3]. wonder products.

Article Designation: Scholarly 2 JTATM Volume 6, Issue 4, Spring 2011

2.2.1 SALIENT FEATURES OF to one chemical reaction. An ordinary ENZYME APPLICATION IN TEXTILE catalyst may be used for several different PROCESS ARE chemical reactions, but an enzyme only works for one specific reaction [5]. Enzymes  Extremely specific nature of must have the correct shape to do their job. reactions involved, with practically Enzymes change their shape if the no side effects. temperature or pH changes, so they have to  Low energy requirements, mild have the right conditions. Conventional conditions of use, safe to handle, chemical processes are generally severe and non- corrosive in their applications. fiber damage may occur. However, enzymes  On account of lesser quantities of are characterized by their ability to operate chemicals used in process as well as under mild conditions. As a result processes ease of biodegradability of may take place without additional harm to enzymes results in reduced loads on the fiber. Enzymes are also readily ETP plants. biodegradable and therefore potentially  Enzymes under unfavorable harmless and environmentally friendly. conditions of pH or temperatures Enzymes are proteins with highly chemically remain in same form but specialized catalytic functions, produced by their physical configuration may get all living organisms. altered i.e. they get “denatured” and lose their activity. For this reason 3.2 MECHANISM OF ENZYME live steam must never be injected in ACTION - LOCK & KEY THEORY a bath containing enzymes and any addition of chemicals to the In the absence of enzymes, chemical enzymes bath must be done in pre- reactions occur only when molecules collide diluted form. while in proper alignment with each other.  Compatibility with ionic surfactants Because molecules are bumping into each is limited and must be checked other randomly, chemical reactions are before use. Nonionic wetting essentially due to chance events. This agents with appropriate cloud points sometimes results in reactions that occur must be selected for high working very slowly, or reactions that do not occur at efficiency as well as for all. Enzymes act like tiny molecular uniformity of end results. machines to ensure that molecules come into  High sensitivity to pH, heavy metal contact with each other and react. Like a key contaminations and also to effective fitting into a lock, chemical molecules fit temperature range. into pocket-like structures located on an  Intense cautions are required in use. enzyme. These pockets hold the molecules in a position that will allow them to react 3. ENZYMES with each other, ensuring that they are close enough together and aligned properly for a Enzymes are biological catalysts. A reaction to occur. In this way, enzymes catalyst is any substance which makes a speed up reactions. The enzymes are not chemical reaction goes faster, without itself changed themselves by the reaction. When being changed. A catalyst can be used over the reaction is complete, enzymes release and over again in a chemical reaction: it the product(s) and are ready to bring does not get used up. Enzymes are very together more molecules and catalyze more much the same except that they can be easily reactions [6]. Enzymes have active centers, denatured by some means. All enzymes are which are the points where substrate made of protein; that is why they are molecule can join. Just as a particular key sensitive to heat, pH and heavy metal ions. fits into a lock, a particular substrate Unlike ordinary catalysts, they are specific molecule fits into the active site of the

Article Designation: Scholarly 3 JTATM Volume 6, Issue 4, Spring 2011

enzyme. The substrate forms a complex with itself is regenerated which is shown in the enzyme. Later the substrate molecule is Figure 1. converted into the product and the enzyme

FIGURE 1. LOCK & KEY MODEL OF ENZYME SPECIFICITY

3.3 ENZYME SOURCES specifications developed in cooperation with the FDA). Commercial sources of enzymes are obtained from three primary sources, i.e., 3.4 ADVANTAGES animal tissue, plants and microbes. These naturally occurring enzymes are quite often  Lower discharge of chemicals and not readily available in sufficient quantities wastewater and decreased handling for food applications or industrial use. of hazardous chemicals for textile However, by isolating microbial strains that workers. produce the desired enzyme and optimizing  Improved fabric quality. the conditions for growth, commercial  Traditionally, to get the look and feel quantities can be obtained. This technique, of stonewashed jeans, pumice stones well known for more than 3,000 years, is were used. However, thanks to the called fermentation. Today, this introduction of cellulase enzymes, fermentation process is carried out in a the jeans industry can reduce and contained vessel. Once fermentation is even eliminate the use of stones. Of completed, the microorganisms are course, a big driver for the jeans destroyed; the enzymes are isolated, and industry is fashion. Enzymes give the further processed for commercial use. manufacturer a newer, easier set of Enzyme manufacturers produce enzymes in tools to create new looks. Although accordance with all applicable governmental many consumers do not want their regulations, including the appropriate jeans to look or feel new, they federal agencies (e.g., Food and Drug usually do not want them to look Administration, United States Department of worn-out or torn. The pumice stones Agriculture, Environmental Protection used to “stonewash” the denim Agency, etc.). Regardless of the source, clothes can also over abrade or enzymes intended for food use are produced damage the garment. By using in strict adherence to FDA‟s current Good enzymes, the manufacturer can give Manufacturing Practices (cGMP) and meet consumers the look they want, compositional and purity requirements as without damaging the garment. defined in the Food Chemicals Codex (a  Less mining, reduced waste, less compendium of food ingredient energy, less clogging of municipal pipes with stones and stone dust,

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fewer worn out machines and pipes Although like all other proteins, enzymes attributed to stones and stone dust. are composed of amino acids, they differ in  More fashion choices longer garment function in that they have the unique ability life/wear due to lower damage of to facilitate biochemical reactions without original fabric. undergoing change themselves. This  Reduced chemical load, reduced catalytic capability is what makes enzymes water consumption, lower energy unique [7]. Enzymes are categorized consumption. according to the compounds they act upon. Some of the most common include; 3.5 TYPES OF ENZYMES proteases which break down proteins, cellulases which break down cellulose, Enzymes are responsible for many lipases which split fats (lipids) into glycerol essential biochemical reactions in and fatty acids, and amylases which break microorganisms, plants, animals, and human down starch into simple sugars. Major types beings. Enzymes are essential for all of enzymes used in the textile wet metabolic processes, but are not alive. processing industries are given in Table 1.

TABLE 1. TYPES OF ENZYMES USED IN TEXTILE INDUSTRY S. Type of enzyme Application No. 1 Amylases To decompose starches in sizing preparations 2 Catalases Act on Hydrogen Peroxide to decompose it into water and oxygen 3 Protease, lipases When combined, act on Proteins, Pectins and natural and waxes to effect scouring pectinase 4 Laccases Decompose indigo molecules for wash-down effect on denim 5 Cellulases Break down Cellulosic chains to remove protruding fibers by degradation & create wash-down effect by surface etching on Denims etc.

3.5.1 AMALYSES temperature range of 50-70°C and at pH 6.0-6.8. Amylases are hydrolase class of (c) Low temperature amylases: Majority enzymes, which hydrolyze 1-4 α glucosidic of fungal amylases which catalyze linkage of amylase and amylopectin of starch hydrolysis in the temperature starch to convert them into soluble dextrins. range of 30-70°C and at pH 6.0-6.8. The following types find major application in textiles: 3.5.2 CELLULASES

(a) Thermostable amylases: Amylases Cellulases are hydrolase class of which catalyze starch hydrolysis in the enzymes which cleavage 1-4β glucosidic temperature range of 70-110°C and at linkage of cellobiose chain or cellulose. The pH 6.0-6.8. commercially available cellulases are a (b) Conventional amylases: Amylases mixture of enzymes viz., Endogluconases, which catalyze starch hydrolysis in the Exogluconases and Cellobiases, Endogluconases are subclass of cellulase

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enzymes which randomly attack the 3.5.4 PROTEASES cellulose enzymes and hyudrolyze the 1-4 β glucosidic linkage of cellobiose chain [8]. Proteases are Hydrolase class of Exoglucanases of cello-biohydrolases are enzymes, classified based on the source again subclass of cellulose enzyme which from which it is extracted, optimum hydrolyses 1-4 β glucosidic linkage of temperature of activity. Proteases precisely cellulose to release cellotiose from the act on peptide bonds formed by specific cellulose chain and Cellobiases are enzymes amino acids to hydrolyze them. Commercial which hydrolyse cellobiose into soluble proteases are available, which can work in glucose units. All these three enzymes act different range of pH and temperature. synergistically on cellulose to hydrolyse Trypsin (pancreatic), Papain based and them. Among the different classes of alkaline proteases find industrial commercially available cellulases, following applications in textiles. types find major application in textiles. 3.5.5 PEROXIDASES (a) Acid Cellulases Peroxidases or Catalases are Acid cellulases are class of enzymes Oxidoreductase class of enzymes. The that act at pH 3.8-5.8 (optimum 4.5-6) and peroxidase enzyme catalyzes the in the temperature range of 30-60°C. The decomposition of hydrogen peroxide in to low temperature range of 30-60°C and water and molecular oxygen as illustrate. conventional acid cellulases act in the temperature range of 45-60°C. 2H2O2 → 2H2O + O2

(b) Neutral Cellulases Catalase is a heam-containing enzyme. Thus, in addition to the protein part of the Cellulase enzymes which act at pH molecule the enzyme contains a non-protein 6.0-7.0 and in the temperature range of 40- part, which is a derivative of heam and 55°C are termed as neutral Cellulases. includes the metal iron. Peroxidases effectively degrade the hydrogen peroxide at 3.5.3 PECTINASES varied pH between 3 to 9 and temperature range 30 - 80 °C. Pectinases are a mixture of enzymes, which along with other such as cellulose, are 3.5.6 LACCASE widely used in the fruit juice industry. Enzymes in this pectinase group include Laccases are Oxidoreductase class of polygalacturonases, pectin methyl esterase enzymes, belonging to bluoxidase- copper and pectin lyases. These pectinase enzymes metalloenzymes. Laccases are generally act in different ways on the pecans, which active at pH 3-5 and in the optimal are found in the primary cell walls of cotton temperature range of 30-50°C. They oxidize and jute. Pectins are large polysaccharide using molecular oxygen as electron acceptor molecules, made up of chains of from the substrate. Their special property of galacturonic acid residues. oxidation of indigo pigments is made use of in textile industries.

Article Designation: Scholarly 6 JTATM Volume 6, Issue 4, Spring 2011

4. DIFFERENT APPLICATIONS enzymatic processes are being developed BIOPROCESSING IN TEXTILE (cellulase, hemicellulase, pectinase and INDUSTRY lipase), which offer the potential to totally replace the use of other chemicals in textile 4.1 BIO-SINGEING preparation processes. Complete removal of starch-containing size without fiber damage This mode of finishing has been is best obtained by using enzymatic desizing specifically developed to achieve clearer agents. Formerly amylase derived from pile on terry towel goods. A treatment with mold, pancreas or malt where used in an enzyme, which is a powerful cellulase desizing. Today liquid bacterial amylase composition, gives clearer look to the pile, preparations dominate. The enzymatic improves absorbency and softness. Earlier, desizing process can be divided into three desizing was carried out by steeping the stages; (a) Impregnation: Enzyme solution fabric with mineral acid, which affected the is absorbed by the fabric. This stage cellulose as well as the color. Use of involves thorough wetting of fabric with enzymes here led to reaction with the starch enzyme solution at a temperature of 70°C or only and thus they assumed considerable higher with a liquid pick up of 1 liter per kg significance. Explaining the action of fabric. Under these conditions there is enzymes, the food consumed by human sufficient enzyme stability (temperature, pH, body was digested due to secretion of the calcium ion level govern the stability). enzyme. At the enzyme-substrate complex During this stage gelatinization of the size level, the concentration of the reactants (starch) is to the highest possible extent, (b) became large and accelerated the reaction Incubation: The enzyme breaks down the while reducing the activation energy barrier. size. Long incubation time allows a low Thus, the reaction which took place at enzyme concentration, (c) After-wash: higher temperature and severe conditions The breakdown products from the size are could be carried out at relatively lower removed from the fabric. The desizing temperatures and milder conditions [9]. process is not finished until the size breakdown products have been removed 4.2 BIO-DESIZING from the fabric. This is best obtained by a subsequent detergent wash (with NaOH) at Before the fabric can be dyed, the the highest possible temperature. applied sizing agent and the natural non- cellulosic materials present in the cotton 4.3 BIO-SCOURING must be removed. Before the discovery of amylase enzymes, the only alternative to Cotton could be treated with remove the starch based sizing was extended bioscouring enzyme although the techno- treatment with caustic soda at high economical parameters were not conductive. temperature. The chemical treatment was But, it had a bright future due to rigorous not totally effective in removing the starch effluent treatment since disposal of both (which leads to imperfections in dyeing) and caustic soda and soda ash was causing also results in a degradation of the cotton environmental concern. The enzymes helped fiber resulting in destruction of the natural, removal of waxes, pectins, sizes and other soft feel, or hand, of the cotton [10]. The use impurities on the surface of the fabric. of amylases to remove starch-based sizing Combination of pectinase and lipase gave agents has decreased the use of harsh best results, but cost of the latter was a chemicals in the textile industry, resulting in deterrent. Advantages of bioscouring were a lower discharge of waste chemicals to the lower BOD, COD, TDS, and the alkaline environment, improved the safety of media of water, extent of cotton weight loss, working conditions for textile workers and which was a boon to the knitting industry, has raised the quality of the fabric. New lower alteration of cotton morphology i.e.

Article Designation: Scholarly 7 JTATM Volume 6, Issue 4, Spring 2011

less damage since it was specific to pectin  Highly suitable for scouring of and waxes and not cellulose besides blends like silk, wool, viscose, increased softness. The lone disadvantage modal, lyocel, and Lycra etc. was that the cotton motes were not removed,  Low TDS in discharge. which warranted peroxide bleaching. In a  Fabric is softer and fluffier than heterogeneous reaction like cotton scouring, conventional scouring, ideal for the kinetics of enzymatic reaction is terry towel/knitted goods. influenced by rate of diffusion of bulky reactants into cotton fiber. In cotton the 4.4 INTEGRATED BIO-DESIZING AND major portion of impurities is located in its BIO-SCOURING primary wall and cuticle of the fiber. This is The integrated Bio-desizing and Bio- favorable for the action of macro – scouring system uses an empirically molecules used in bio-scouring enzymes developed enzyme formulation, based on [11]. Factors influencing scouring are the amylase, pectinase, protease and lipase that nature of the substrate, the kind of enzyme act synergistically, resulting in desizing and used, the enzyme activity, the use of scouring of cotton goods, under mild surfactants and mechanical impact. It was conditions. observed that, during pectinase scouring, much less wax was removed compared with 4.5 BIO-BLEACHING the alkaline scouring. If the treatment was combined with surfactant treatment, results It was applicable for all kinds of equivalent to alkaline scouring could be colors and a single enzyme could be used in achieved. A water treatment at 100°C is the textile industry. Biobleaching had been reported to increase the effectiveness of the adapted for denim. Indigo specific lipases subsequent scouring of cotton fabric with a were used to bleach indigo. Earlier denim combination of pectinase, protease and was bleached with chlorine to get lighter lipase, results equivalent to alkaline scouring denim or wash down effect. Lipase could be achieved. Traditionally this is combination was used successfully and if achieved through a series of chemical this could be extended to other colors, this treatments and subsequent rinsing in water. would become an important enzyme in This treatment generates large amounts of future. The advantages were environment salts, acids and alkali and requires huge friendly application, non-AOX generation amounts of water. and cellulose was not affected. A biobleaching or lipase treatment on denim gave Bio-scouring systems an authentic wash resulting in an excellent The bio-scouring process is built on ▪ look, which was better than a neutral wash Protease, ▪ Pectinase & ▪ Lipase enzymes and a grey cast, which was used in that act on proteins, pectin‟s & Natural bleaching. Amylase and lipase were used for waxes to effect scouring of cotton. desizing and cellulase for aberration. Lactase was introduced for bleaching of Advantages of bio-scouring: indigo [12].  Milder conditions of processing, low consumption of utilities, 4.6 PEROXIDE KILLERS excellent absorbency in goods.  No oxy-cellulose formation and It ensured shade quality particularly less strength loss because of with reactive dyes, reduced the complexity absence of heavy alkali in bath. of treatment after peroxide bleaching and  Uniform removal of waxes results conserved water. In case of reactive dyeing, in better levelness in dyeing. after bleaching it was vital that the peroxide residues must be cleared out of the system and as such there were no fool proof ways of

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such clearance, which entailed several 4.8 BIO-POLISHING rinsing operations or reduction treatments. Empirically, it was difficult to know how It was perceived that bio-polishing much quantity of reducing agent was and fading or bio-polishing and wash down required to react with the peroxide left in the were two different operations. But both of bath. In the event either of them happened to them basically employed the same action. be excess, it might affect the dyeing. They degraded the cellulose due to abrasion Therefore, after bleaching, the bath should or friction between fiber to fiber or fiber to be neutralized with peroxide killers like metal resulting in removal first from peroxidase or catalase followed dyeing with cellulose and then surface bleeding. Bio- reactive dyes. They did not affect reactive polishing before dyeing could increase depth dyes and only react with the peroxide. These apparently due to clarity of shade. Bio- catalysts were fastest acting type as 1 polishing or cellulase enzyme treatment of molecule of catalyst destroyed 5 million lyocel type of regenerated cellulose could molecules of peroxide or 700 times its own produce peach like effect. Bio-polishing weight of peroxide. give cleaner appearance to the garment besides wash down effect. If it was sulphur 4.7 ENZYMES EFFECT ON COLOR or pigment dyed goods or ring dyed fabric, wash down effect as well as cleaning of Hydrolases and oxireductases fabric surface could be obtained. The result constituted important class of enzymes surface hair was removed, reduced pilling, which dealt with color in textile application. better print registration and color brightness. Due to effect of enzyme and physical Size of cellulase enzyme was about 8nm as aberration of cellulose, the exposed areas also the size of cellulose monomer, which became white as well as indigo dyed. This was in similar region [14]. Bio-polishing, a kind of effect on denim was called salt and technique first adopted by the Danish Firm, pepper effect. The more contrast, better was Novo Nordisk for the finishing treatment of the denim wash. Some of the denims had cellulosic fabrics with cellulase enzymes. blue or greyer cast because they were woven The main objectives of the bio-polishing is with one up or two down and one of the yarn to upgrade the quality of the fabric by was colored while the other wasn‟t. Thus, removing the protruded fibers from the the effect was created with the combination surface and modification of the surface of the hydrolysis of 1-4 glucose linkage in structure of the fiber, thereby making it soft cellulose and the abrasion e.g. turbulence of and smooth. In conventional process friction of metal to metal or fiber to fiber led protruded fibers are removed by singing to denim appearance. Combination of process and smoothness imparted by enzyme, sand blasting and bleach evolved a chemical treatment. The conventional fashion recently. Sand blasting was enzyme methods are temporary, fibers return on the treatments which subject the denim fabric to surface of the fabric and chemicals are sand at high pressure with consequent removed after few washing and fuzz is exposure of white area while blowing off formed [15, 17]. The fuzz on the surface surface color followed by a treatment of the spoils the fabric appearance and generates fabric again with enzyme, leading to a salt customer‟s dissatisfaction whereas and pepper effect and bleached to reduce the biopolishing is permanent and it not only color value. Furthermore, after sand keeps the fabric in good condition after blasting, treatment with enzyme followed by repeated washing but also enhances feel, over dyeing of the abraded areas produced color, drapability etc consequently products typical effects on denim [13]. become more attractive to the customer and fetch better prices.

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The bio-polishing treatment offers the The goods are treated with cellulose enzyme following advantages: based formulation to achieve dissolution of  Improved pilling resistance. cellulosic fibers. In the bio-carbonizing  A clearer, lint and fuzz-free surface process the goods are treated with a structure. cellulose enzyme based formulation  Improved drape ability and softness. “chemizyme UZ” to achieve dissolution of  The effects are durable. cellulosic component. The goods are padded  Slight improvement in absorbency. in a warm solution of this product and  Fashionable effects on fabric like batched on a roll under normal conditions distressed look of denim. and are washed off after 12-16 hours. This process offers an eco friendly option to the Examples of some cellulases are obnoxious use of strong acids. Aspergillus Niger, Trichoderma longibrachiatum, Fusarium solani and 4.10 DEGUMMING OF SILK Trichoderma viride. The enzymes are bimolecular of about 20 amino acids with Silk is made up of two types of molecular weight ranging from 12,000 to proteins like fibrin and ceresin. In the case 1,50,000 and therefore they are too large to of enzymatic treatment, a ceresin specific penetrate the interior of a cellulosic fiber. protein was used to degum the silk without Hence, only 1,4 β-glucosidic bonds at the causing damage, impart softness and surface of cellulose fiber are affected. This increase dye uptake of about 30%. If silk results in removal of surface hairs which are was degummed by alkaline treatment, there responsible for improvement in the hand and was damage to fibrin and heavy weight loss. feel of the fabric due to surface etching. Biopolishing or bio finishing can be 4.11 TEXTILE AUXILIARIES performed continuously and in batch form but the treatment conditions are more easily Textile auxiliaries such as dyes could controlled in batch processes for which be produced by fermentation or from plants winches, jiggers, jet or over flow machines in the future (before invention of synthetic are suitable. In principle, biofinishing can be dyes in the nineteenth century many of the carried out along with any other stage of colors used to dye textiles came from plants textile finishing, with dyeing for example e.g. wood, indigo and madder). Many provided that both processes are subject to microorganisms produce pigments during identical conditions. However, it is best their growth, which are substantive as carried out after bleaching and before indicated by the permanent staining that is dyeing. The conditions for bio polishing are often associated with mildew growth on as follows: textiles and plastics. It is not unusual for some species to produce up to 30% of their 4.9 BIO-CARBONIZING dry weight as pigment. Several for these microbial pigments have been shown to be Polyester / cellulosic blends after benzoquinone, naphthoquinone, dyeing and/ or printing are occasionally anthraquinone, perinaphthenone and benzo treated with strong solution of sulphuric acid fluoranthene quinone derivatives, to dissolve cellulosic component. The resembling in some instances the important resultant goods are soft and have a peculiar group of vat dyes. Microorganisms would fluffy feel. This process is risky due to therefore seem to offer great potential for highly corrosive acid that is also difficult to the direct production of novel textile dyes of treat in an ET plant. The process developed dye intermediates by controlled fermentation at UNO, has none of the above drawbacks. It techniques replacing chemical syntheses, offers a safe and eco-friendly to the which have inherent waste disposal obnoxious practice of using sulphuric acid. problems (e.g. toxic heavy metal

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compounds). The production and evaluation disposal, on the contrary biological of microbial pigments as textile colorants is processes completely mineralize pollutants currently being investigated. Another and are cheaper. Instead of using the biotechnological route for producing chemical treatments, various biological pigments for use in the food, cosmetics of methods can be used to treat the water from textile industries is from plant cell culture. the textile industry. These methods include, One of the major success stories of plant biosorption, use of enzymes, aerobic and biotechnology so far has been the anaerobic treatments etc. Only commercial production since 1983 in Japan biotechnological solutions can offer of the red pigment shikonin, which has been complete destruction of the dyestuff, with a incorporated into new range of cosmetics. co-reduction in BOD and COD. In addition, Traditionally, shikonin was extracted from the biotechnological approach makes the roots of five year old plants of the efficient use of the limited development species Lithosperum erythrorhiz where it space available in many traditional dye makes up about 1 to 2 per cent of the dry house sites. The synthetic dyes are designed weight of the root,. Din tissue culture, in such a way that they become resistant to pigment, yields of about 15 per cent of the microbial degradation under the aerobic dry weight of the roof cells has been conditions. Also the water solubility and the achieved. high molecular weight inhibit the permeation through biological cell 4.12 ENZYMATIC DECOLORIZATION membranes. Anaerobic processes convert the organic contaminants principally occupy In textile dyeing as well as other less space; treat wastes containing up to industrial applications, large amounts of 30,000 mg/l of COD, have lower running dyestuffs are used. As a characteristic of the costs and produce less sludge. Azo dyes are textile processing industry, a wide range of susceptible to anaerobic biodegradation but structurally diverse dyes can be used in a reduction of azo compounds can result in single factory, and therefore effluents from odor problems. Biological systems, such as the industry are extremely variable in biofilters and bioscrubbers, are now composition. This underlines the need for a available for the removal of odor and other largely unspecific process for treating textile volatile compounds. The dyes can be waste water. It is known that 90% of removed by biosorption on apple pomace reactive dyes entering activated sludge and wheat straw. The experimental results sewage treatment plants will through showed that 1 gm of apple pomace and 1 gm unchanged and be discharged in to rivers. of wheat straw, with a particle size of 600 High COD and BOD, suspended solids and μm, where suitable adsorbents for the intense color due to the extensive use of removal of dyes from effluents. Apple dyes characterize wastewater from textile pomace had a greater capacity to absorb the industry, especially process houses. This reactive dyes, compared to wheat straw. type of water must be treated before discharging it into the environment. The 4.13 FINISHING OF COTTON KNITS water must be decolorized; harmful chemicals must be converted into harmless Cellulase enzyme treatments chemicals. Biological treatments have been increasingly find applications in cotton used to reduce the COD of textile effluents. hosiery sector to enhance aesthetic feel as Physical and chemical treatments are well as surface clarity. Ultrazyme Super is effective for color removal but use more an enzyme –based formulation, well suited energy and chemicals than biological for use in winches or high turbulence soft processes [2, 10]. They also concentrate the flow machines. Adequate caution must be pollution into solid or liquid side streams exercised to deactivate residual enzyme by that require additional treatments or elevating temperatures to around 80-85°C,

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otherwise the reaction would continue to controlling the back staining effect e.g. take place resulting in loss of physical Sandoclear IDS Liq is claimed to be very strength of goods. efficient in removing back-staining. Treatment with proteases during rinsing or 4.14 BIO-DENIM WASHING at the end of the cellulase washing step results in significant reduction of back Another use of cellulase enzyme is in staining and improved contrast. The use of the fading of denims. Denims are enzyme for denim washing has the manufactured from indigo dyed warp yarns. following advantages over pumice stone The dyes are mainly absorbed on the surface washing. of the fiber, a phenomenon technically termed as ring dyeing. The fiber surface  Superior garment quality etching with cellulase enzymes results in  Increased load handling (30 – 35%) exposure of the undyed core of the fibers  Environment friendly processing which gives a faded look to the denim. The  Less damage to seams, edges and dye removal is further facilitated by the badges mechanical abrasion. Earlier the effect was  Extra softener not required obtained by washing denim with pumice  Less equipment wear stones. Pumice stones are soft, light and  Easy handling of floors and sewers porous in nature. About 1-2 Kg pumice  No handling of pumice/ ceramic stones per pair of jeans were used to get the stones desired worn out look. Though stone washing gives the desired result but it has 5. CONCLUSIONS got several disadvantages. The major problem with stone washing is that lot of Biotechnology is a multidisciplinary sludge gets deposited in the effluent tank field, which has been considered in several due to the wear of the pumice. The sludge National Development Programs as one of has to be separated from effluent water and the strategic areas and as source of disposed off. The use of stones was, considerable amount of new products with therefore, replaced by cellulase enzymes. high impact in textile industries. Enzymes When indigo dye is released to the wash are a sustainable alternative to the use of liquor during washing, the solution turns harsh chemicals in industry. Because dark blue. Indigo dye has two amino groups enzymes work under moderate conditions, which are capable of getting protonated in such as warm temperatures and neutral pH, an acidic media. Due to protonation, the they reduce energy consumption by dyestuff gains an overall positive charge on eliminating the need to maintain extreme the contrary; cellulose maintains its negative environments, as required by many charges in an acidic media [15-16]. Positive chemically catalyzed reactions. Reducing and negative charges attract one another in energy consumption leads to decreased solution. Therefore, in acidic pH the affinity greenhouse gas emissions by power stations. of indigo for cotton increases. Some of this Enzymes also reduce water consumption indigo redeposit on the whiter parts of the and chemical waste production during denim fabric which spoils the color contrast manufacturing processes. Because enzymes of the stone wash effect. This phenomenon react specifically and minimize the is known as “back staining”. Back –staining production of by-products, they offer problem is more evident with acid minimal risk to humans, wildlife, and the cellulases. The use of neutral cellulases is environment. Enzymes are both recommended to control the back staining economically and environmentally feasible problem because of their better control in because they are safely inactivated and decoloration effect and resistance to back create little or no waste; rather than being staining. Some auxiliary chemicals help in discarded, end-product enzymatic material

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may be treated and used as fertilizer for 7. Chandrika G P, Cross linking of enzymes farmers' crops. Bioprocessing done with for improved stability and performance, enzymes on organic cotton fabrics will Current Opinion in Biotechnology, vol. produce 100% eco-friendly garments and 10, 1999, 331-335. apparel, which is very advantageous for the 8. Nallankilli.G, “Enzymes in Textile wet health of the consumers and the processing”, Textile Industry and Trade environment. Bioprocessing with its Journal, 30 (1), 51, 1992. pervasive field of application surely going to 9. Lopmundra Nayak, P.S.Nayak, „A part of conquer the world of textiles and will make Ensuring Eco-Standard‟, Clothesline, it to rich the pinnacle of its performance. 2004. There are few to enunciate, however many 10. Edward Menzes & Bharat Desai, Rossari such potentials are yet to explore. Bio- biotech, „Water in Textile Wet processing in textiles provides to be a boon processing-Quality and Measures‟, to the ever changing conditions of the Clothesline, 2004. ecology as well as economy. 11. Nalankilli.G, „Application of Enzymes in Wet Processing of Cotton‟, Indian REFERENCES Textile Journal, C3 (12), 110, 1992. 12. Buschie-diller G, Zeronian S H, Pan N 1. Churi R Y, Khadilkar S M and Sule S, and Yoon M Y, Enzymatic hydrolysis of Enzyme Systems for processing cotton, linen, ramie and viscose fabric, cellulosic textiles, Colourage, April Text Res. J., 64, 1994, 240-279. 2004, 37-42. 13. Emilla csiszar, Gyorgy szakacs and 2. Abadulla A , Enzymatic decolourization Istvan rusznak, Combining traditional of Textile Dyeing Effluents, Text Res. cotton scouring with cellulase enzymatic J., 70 (5), 2000, 409-414. treatment, Text. Res. J., 68(3), 1998, 3. Cavaco-Paulo A, G Gubitz, Graz “Textile 163-167. processing with enzymes, Wood head 14. Hassan K Sreenath, Arun B Shah, Vina Publishing Limited, 2003, ISBN-13: 978 W Yang, Mahendra M Gharia and 1 85573 610 8. Thomas W Jeferies, Enzymatic 4. Gaffar Hossain M, Multifunctional polishing of jute/cotton blended fabrics, modification of wool using an J. Ferm. Bioeng., 81(1), 1996, 18-20. enzymatic process in aqueous- organic 15. Kumar V S, Meenakshisundaram S and media, Journal of biotechnology, 141 Selvakumar N, Conservation of (1), 2009, 47-59. cellulase enzyme in biopolishing 5. Tzanko Tzanov, Protein interactions in application of cotton fabrics, J. Text. enzymatic processes in textiles, Inst., 1, 2008, 339-346. Electronic Journal of Biotechnology, 16. Pedersen G L, Screws G A and Cedroni ISSN: 0717-3458, Vol.6 No.3, 2003, 85- D M, Bio-polishing of cellulosic fabrics, 93. Can. Text J., 109, 1992, 31-35. 6. Andreaus J, Campos R, Gübitz G and 17. Tyndall R M, Application of cellulase CAVACO-PAULO A, Influence of enzymes to cotton fabrics and garments, cellulases on Indigo Back staining, Text Text. Chem. Color., 24, 1996, 23-26. Res. J., vol. 70, 2000, 628-632.

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