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Understanding Textile Manufacturing Process in the light of Textile Wastewater Types and Chemicals Used

Textile industry deploys many different process stages in its manufacturing life cycle which involves both mechanical processing and wet-treatment processes. The mechanical processes are spinning, knitting, weaving and garment production. The wet processes are sizing, desizing, scouring, bleaching, mercerizing, dyeing, printing and finishing. Table 1 lists the types of waste generated in every stage of textile production.


Table 1. Types of Textile Waste Produced by Process (Water, Solid and Emission)

Process Wastewater Solid Waste Emission
Fiber preparation Little or none Fiber waste and packaging waste Little or none
Yarn spinning Little or none Packaging wastes, sized yarn, fiber waste, cleaning and processing waste Little or none
Sizing BOD, COD, metals, cleaning waste, size Fiber lint, yarn waste, packaging waste, unused starch-based sizes VOCs
Weaving Little or none Packaging waste, yarn and fabric scarps, used oil Little or none
Knitting Little or none Packaging waste, yarn and fabric scarps Little or none
Tufting Little or none Packaging waste, yarn and fabric scarps, offspec fabric Little or none
Desizing BOD from sizes lubricants, Packaging waste, fabric VOCs from glycol esters
biocides, anti-static compounds lint, yarn waste, cleaning and maintenance materials
Scouring Disinfectants, insecticide recisues, NaOH, detergents oils, knitting lubricants, spin finishes, spent solvents Little or none VOCs from glycol esters and scouring solvents
Bleaching H2O2, stabilizers, high pH Little or none Little or none
Singeing Little or none Little or none small amounts of exhaust gasses from the burners exhausted with components
Mercerizing High pH, NaOH Little or none Little or none
Heat setting Little or none Little or none volatilization of spin finish agents-synthetic fiber manufacture
Dyeing Metals, salt, surfactants, organic processing, assistants, cationic materials, color, BOD, COD, sulphide, acidity/alkalinity, spent solvents Little or none VOCs
Printing Suspended solids, urea, solvents, color, metals, heat, BOD, foam Little or none solvents, acetic acid – drying and curing oven emission combustion gasses
Finishing COD, suspended solids, toxic materials, spent solvents Fabric scraps and trimmings, packaging waste VOCs, contaminants in purchased chemicals, formaldehyde vapours, combustion gasses
WordPress Responsive Table
textile process water treatmentA variety of chemicals are used in each and every stage of the production process of textiles. These chemicals end up as waste once their intended function is achieved in the production process. These spent up chemicals end up as effluent and need to be treated accordingly for a stricter compliance of the rules and regulations of Wastewater Management of the State. Table 2 lists down the type of chemicals used in each stage of the production process.




Table 2: Chemicals Used in Different Production Processes In Textile Manufacturing

STEP 1 FIBRE PRODUCTION Plant fibres are produced from Cotton, linen, hemp, bamboo and any other plants with extractable cellulose. pesticides, insecticides, fertilisers
STEP 1 FIBRE PRODUCTION Animal fibres are made up of proteins and commonly used animal fibres are wool and silk pesticides, insecticides, scouring chemicals
STEP 1 FIBRE PRODUCTION Man-made fibres are based on cellulose extracted from wood pulp and common one is viscose (rayon). acids, bases, process chemicals
STEP 1 FIBRE PRODUCTION Synthetic fibres are produced from monomers sourced from fossil oils and common one is polyester. petroleum-based feedstock, dyes, pigments, catalysts, stabilizers
STEP 2 YARN PRODUCTION The collected fibres are spun into yarn which is a mechanical production process. To increase the strength of the fibre, fibre cohesion and reduce friction, spinning oils are added. spinning oils
STEP 3 FABRIC PRODUCTION Weaving sizing chemicals
STEP 3 FABRIC PRODUCTION Knitting lubricants
STEP 3 FABRIC PRODUCTION Non-woven solvents, adhesives, binders
STEP 4 PRE-TREATMENT Washing (cleaning of the fabric) Detergents, solvents
STEP 4 PRE-TREATMENT De-Sizing (removing the sizing chemicals from the warp) Enzymes
STEP 4 PRE-TREATMENT Scouring (Removing fatty waxes and greases from natural fibres) Detergents, bases, solvents
STEP 4 PRE-TREATMENT Bleaching (Making the fibre whiter to make the fibres more absorbent) Bleaches
STEP 4 PRE-TREATMENT Mercerizing (making cellulosic fibres strong and swell to facilitate dyeing) Bases
STEP 4 PRE-TREATMENT Carbonizing (removes vegetable residues) Acids
STEP 5 DYEING & PRINTING Dyeing Dyes, Pigments
STEP 5 DYEING & PRINTING Printing pigments, dyes, binders and polymeric resin (acrylates, PVC, PUR), plasticisers
STEP 5 DYEING & PRINTING Washing Detergents
STEP 6 FINISHING TREATMENTS Handle modification Softeners (polyetylen, quartenary ammonium compounds, silicones, polyurethanes)
STEP 6 FINISHING TREATMENTS Handle modification Stiffeners (starches resins, polyvinylacetat, polyvinylalcohol)
STEP 6 FINISHING TREATMENTS Crease resistance (anti-wrinkling, easy care) Resins, Formaldehyde based
STEP 6 FINISHING TREATMENTS Antistatic treatment cationic softeners, polyglycols
STEP 6 FINISHING TREATMENTS Antibacterial/anti-odor treatment biocides as silver, triclosane
STEP 6 FINISHING TREATMENTS Water repellance water repellents based on waxes, silicones, fluorocarbons
STEP 6 FINISHING TREATMENTS Oil/soil repellance oil/soil repellents based on fluorocabons
STEP 6 FINISHING TREATMENTS Flame retardance flame retardants (halogenated, phosphor based)
STEP 6 FINISHING TREATMENTS (Protective) coatings Acrylates, polyurethanes, silcones, PVC with plasticisers
STEP 6 FINISHING TREATMENTS Laminated films and membranes in the material layers: Different types of polymers (polyurethane, polytetrafluoretylen, modified polyester)
STEP 6 FINISHING TREATMENTS Laminated films and membranes in adhesives: Different types of polymers such as polyurethane based, and thermoplastic polymers
STEP 6 FINISHING TREATMENTS Garment treatments for fashion Potassium permanganate, sodium hypochlorite, calcium hypochlorite, sodium hydro sulphite, potassium dichromate, formaldehyde resins, cationic softeners, cationic silicone softeners
STEP 7 TRANSPORT & STORAGE Transport Preparation Dimethyl fumarate, ethylene oxide, methylbromide, 1,2 dichloroethane, phospine, dichloromethane, sulfuryl fluoride
WordPress Responsive Table
To produce a kilogram of textiles, approximately 200 litre of water is utilized. Ntuli F, Omoregbe I, Kuipa P, Muzenda E, Belaid M (2009) have reported a concise percentage split of water used in a textile manufacturing process: “38 % of water is used during process of bleaching, 16 % in dyeing, 8% in printing, 14 % in boiler and 24 % for other uses”. The textile wastewater effluent contains high amounts of suspended and dissolved solids, biological oxygen demand (BOD), chemical oxygen demand (COD), chemicals, trace metals like Cr, As, Cu and Zn and color.
Hence it is a mandate to treat the textile wastewater with right care and technology to safeguard the environment.

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