Research libraryWater, Dye and Energy per Unit
Chapter 05 of 14 · Part II · Draft web edition
Uneven or incomplete preparation propagates extra water, heat and correction through every later stage.
The cloth is woven from this chapter's 5 exhibits: each weft is one exhibit's own data, normalised; each warp group is a section. The probe reads the exhibit's own value where it crosses. Procedural visualisation, not a measurement.
Read-out
Derived process and genealogy sequence from S02, S16 and S0503. Each stage records water, steam, electricity and chemical inputs alongside substrate release checks before the lot enters dyeing.
Unit: . Status: derived. Sources: S02, S16, S0503.
Overture · 1 min
A dyehouse cannot control its water, chemical or thermal intensity if it treats fabric preparation as an unmeasured prologue outside the colour boundary.[S02][S37] Every reactive, vat or direct dye bath acts on the surface delivered by desizing, scouring, bleaching and, where specified, mercerisation.[S01][S02] Raw cotton enters wet processing with 4 to 10 percent natural non-cellulosic impurities by fibre mass, including hydrophobic waxes, pectins, proteins, hemicelluloses, mineral salts and pigments in the cuticle and primary wall.[S0501][S0504] Woven grey cloth adds warp sizing agents applied for weaving, while knitted greige fabric carries needle oils and lubricants.[S01][S03] When those barriers are removed unevenly, or when residual alkali, starch or hydrogen peroxide enters the dye vessel, the dyebath fails to exhaust and fix uniformly, forcing shading additions, stripping, re-dyeing, extra hot rinsing and stenter drying.[S16][S37][S0501][S0503] For Green Future Tech Limited (GFT) in Hong Kong SAR and its Cameroon textile programme, where the sector baseline prepared on 31 January 2024 records about 95 percent of cotton fibre exported raw and 5 percent processed locally against a 2030 target of 50 percent, preparation must be metered, tested and released inside the same batch ledger as colouration.[R06][R07][S24]
5.1
Wet processing consumes 60 to 90 percent of process water in textile manufacturing, with preparation carrying a major share of hydraulic volume and organic effluent load.[S03] In the International Finance Corporation (IFC) Environmental, Health, and Safety Guidelines for Textile Manufacturing, desizing, scouring, bleaching and mercerising are sequential substrate-modification steps preparing fabrics for coloration and finishing.[S01] Woven grey fabrics arrive bearing warp sizing compounds: native or modified starches, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), polyacrylates, galactomannans, tallow, paraffin waxes and spinning oils.[S01][S03] Knitted greige fabrics bypass warp sizing but carry circular-knitting lubricants, needle oils and wax emulsions alongside native cotton impurities.[S01][S0501]
Because spinning, sizing and weaving vary across suppliers, two rolls of grey cotton with identical mass per square metre can present different chemical loads to the preparation range.[S01][S02] The European Commission Best Available Techniques (BAT) Reference Document for the Textiles Industry emphasises that water emissions, chemical handling and energy use are coupled from the moment grey fabric enters pretreatment.[S02] IFC notes that biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) from desizing represent 35 to 50 percent of a mill's organic wastewater load, generating compartment COD concentrations up to 20,000 milligrams per litre (mg/L) when starch and sizing auxiliaries are washed out.[S01] Literature reviewed by VTT Technical Research Centre of Finland identifies desizing and scouring as the most chemically polluting stages of wet processing, discharging starches, waxes, fats, hemicelluloses, surfactants and strong alkali.[S03]
A process map starting at the dyebath fill valve misses the largest source of organic load and a major consumer of water and steam.[S01][S16] In the composite-plant thermal model analysed for textile wet processing in China, Japan and Taiwan, preparation (desizing, scouring, bleaching and mercerising), dyeing, printing and finishing account for 50 percent of plant thermal energy demand, relying on hot water and steam near 90 to 120 degrees Celsius.[S16][S0503] Recording grey-fabric mass at receipt without logging size formulation, add-on share and impurity profile prevents separating raw-material effects from machine-control effects.[S02][S29]
Excluding preparation from a dye-per-kilogram or litre-per-kilogram claim creates an accounting distortion whenever a facility compares dyeing technologies or buys pre-prepared fabric.[S02][S24] Under Higg Facility Environmental Module (FEM) rules, a facility manufacturing both fabric and finished products must track energy and water separately by facility type so integrated totals do not obscure process intensity.[S24] A dyehouse that buys scoured and bleached cloth (or transfers pre-prepared lots from an unmetered bay) and reports only dyebath and post-dye rinse water appears to achieve low intensity per kilogram, when desizing, caustic scouring and peroxide bleaching occurred upstream of its meter boundary.[S01][S03][S24]
To prevent truncation, GFT structures the wet-processing ledger as a chain of custody from grey or greige receipt to accepted shade release (Exhibit 19).[S02][S16][S0503] Each preparation stage is a resource node consuming metered water, steam, electricity and chemicals while transforming substrate properties required by the next bath.[S02][S16]
The flow architecture in Exhibit 19 sets two rules for the GFT resource ledger.[S02][S16] First, no fabric lot enters dyeing without passing an explicit absorbency and residual-chemistry release gate (gate) binding the preparation lot identifier to the dye-lot identifier.[S02][S37] Second, whether a woven lot travels through the optional mercerisation branch (mercer) or moves directly from bleaching (bleach) to the release gate, all water, chemical and thermal inputs accumulated along its path remain attached to the batch record, populated from calibrated submeters rather than process diagrams.[S16][S18][S24][S0503]
5.4
Exhibit 209 paragraphs step it
Read-out
Illustrative prioritisation of preparation release checks by routine laboratory testing effort (x) and downstream dyeing reprocessing risk avoided (y), based on mechanisms in S02, S37, S0501 and S0503. Thresholds must be set by product trials.
Unit: illustrative control index (0 to 10). Status: illustrative. Sources: S02, S37, S0501, S0503. Illustrative figures are teaching examples, not measured factory results.
A bleached cotton roll that looks white under inspection lamps can still fail in the dyebath if its hydrophilicity, residual peroxide or extractable pH varies from selvedge to centre or head to tail.[S02][S0501][S0503] In raw cotton, non-cellulosic impurities account for roughly 5 percent of fibre weight (4 to 10 percent range), forming a hydrophobic cuticle where alpha-1,4-linked D-galacturonic acid pectin chains cement waxes, fats and proteins to the cellulose wall.[S0501][S0504] Unless this sheath is stripped during scouring, dye liquor cannot wet the fibre evenly or diffuse into micropores during exhaustion.[S31][S0501]
Conventional preparation removes warp starch by acid, oxidative or alpha-amylase desizing, and then strips the cuticle by alkaline scouring in sodium hydroxide (NaOH, 1.5 to 10 g/L in batch trials or 2 to 5 percent on fabric weight) at 90 to 100 degrees Celsius for 45 to 60 minutes with surfactants and sequestering agents.[S0501][S0504] Harsh caustic treatment saponifies fats and emulsifies waxes, but also degrades cellulose and generates alkaline effluent with high BOD, COD and total dissolved solids (TDS).[S0501][S0503] Enzymatic desizing with alpha-amylase at pH 5.5 to 6.5 and 30 to 60 degrees Celsius cleaves internal alpha-1,4 glycosidic bonds in starch without damaging cellulose, accounting for 30 percent of the industrial enzyme market.[S0503] Enzymatic bioscouring using pectinases, xylanases, cutinases or lipases operates at 50 to 55 degrees Celsius and pH 5.0 to 8.5, lowering effluent BOD, COD and TDS by over 50 percent compared with alkaline scouring while preserving strength.[S0501][S0503]
Experimental comparisons confirm why absorbency must be measured quantitatively.[S0501] On 100 percent cotton single-jersey knit fabric (28 Ne, 150 g/m2) at a 1:15 liquor ratio, caustic scouring (1.5 g/L NaOH, 100 degrees Celsius, 45 minutes) achieved an average water-drop wetting time of 1.90 seconds and 3.8 percent weight loss.[S0501] Enzymatic scouring with pectate lyase (0.5 to 0.8 percent on fabric weight, 55 degrees Celsius, 60 minutes, pH 5.0 to 5.5) and synthetic surfactant achieved wetting times of 0.76 to 5.23 seconds (weight loss 2.4 to 4.3 percent), whereas 0.5 percent enzyme with 1 to 2 g/L soapnut extract averaged 4.86 seconds (3.45 to 5.77 seconds) at 3.1 to 3.8 percent weight loss, inside the 3 to 6 percent industrial window protecting bursting strength (408 kilopascals grey, 369 kilopascals caustic, and 312.50 to 383 kilopascals enzymatic).[S0501] Over-dosing soapnut raised wetting time to 10.00 seconds via surfactant-enzyme interactions, proving that bio-based recipes require batch wetting verification.[S0501]
Bleaching introduces a second hazard to downstream dyeing.[S01][S0503] Cotton mills bleach with hydrogen peroxide (H2O2) in an alkaline bath at 90 to 120 degrees Celsius.[S0503][S0504] IFC guidelines recommend hydrogen peroxide over chlorine bleaches because sodium hypochlorite forms adsorbable organic halogens (AOX, trichloromethane) threatening the 1 mg/L effluent guideline limit, and advise replacing poorly bioeliminable chelators (EDTA and DTPA) with biodegradable stabilisers.[S01] After peroxide bleaching, 10 to 15 percent of applied H2O2 remains; unless removed by rinsing or decomposed into water and oxygen by catalase enzyme before dyeing, residual peroxide attacks reactive dye chromophores and causes right-first-time failure.[S37][S0503]
Because preparation defects are cheaper to correct before dye and salt are dosed, GFT treats substrate release as a mandatory laboratory gate.[S02][S37] In a one-bath scouring and bleaching study on greige knitted cotton at 90 degrees Celsius (4 g/L scouring agent and 6 g/L of 30 percent H2O2), extending duration from 30 to 45 and 60 minutes raised whiteness from 68.07 to 73.63 and 77.04 (76.54 at 75 minutes).[S0504] At 60 minutes, prepared cotton achieved 238 percent water absorptivity, a 2.48 second droplet diffusion time (below the 3-second GB/T 21655.1-2008 threshold), and 15-minute wicking heights of 10.4 centimetres warp and 10.1 centimetres weft.[S0504]
To operationalise these checks, Exhibit 20 positions eight preparation control variables across laboratory testing effort on the horizontal axis and downstream reprocessing risk avoided on the vertical axis.[S02][S37][S0501][S0503]
As Exhibit 20 shows, fast checks in the upper-left quadrant (drop wetting time, residual peroxide, extract pH, iodine starch rating and feedwater hardness) require minutes of technician time yet intercept the main causes of unlevel dyeing, shade drift and dye hydrolysis.[S37][S0501][S0503] Intensive measurements in the upper-right quadrant (wicking profiles and mercerisation barium activity or crystallinity checks) serve as route-specific gates during recipe qualification and mercerised-lot release.[S0502][S0504] Because the coordinates in Exhibit 20 are an illustrative control-design index rather than a plant regression, each facility pairs it with the field dictionary in Exhibit 21 and sets numerical limits from product trials.[S02][S37]
Together, Exhibit 20 and Exhibit 21 turn BAT guidance on preparation control into an auditable table storing wetting time, extract pH, residual peroxide and whiteness beside metered litres and megajoules, with product-specific thresholds verified against first-pass colour yield.[S02][S37][S0501][S0503]
5.7
Unmercerised baseline
Unmercerised baseline: total 1,850. Running total 1,850 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
Mercerise hot wash
Mercerise hot wash: adds 420. Running total 2,270 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
Caustic evaporator duty
Caustic evaporator duty: adds 310. Running total 2,580 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
Warm rinse recovery
Warm rinse recovery: removes 190. Running total 2,390 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
Lower dyebath heat
Lower dyebath heat: removes 140. Running total 2,250 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
Avoided re-dye cycle
Avoided re-dye cycle: removes 230. Running total 2,020 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
Net mercerised route
Net mercerised route: total 2,020. Running total 2,020 MJ thermal energy per 100 kg accepted fabric (illustrative) · illustrative
The method behind it: Worked example.
Illustrative single-unit thermal ledger for a 100 kg cotton woven lot, showing how mercerisation hot-wash and alkali-recovery heat duties offset downstream dyeing and reprocessing heat changes. Process relationships follow S16, S03 and S0502; water (L/kg) and caustic soda (kg/kg) are tracked in separate physical ledgers, not subtracted from MJ.
Unit: MJ thermal energy per 100 kg accepted fabric (illustrative). Status: illustrative. Sources: S16, S03, S0502. Illustrative figures are teaching examples, not measured factory results.
5.7 · the bodyExhibit 22 above; its figures are illustrative where marked.
Mercerisation shows why dyehouse savings cannot be evaluated inside the dye vessel alone.[S16][S0502] The textile electrification study notes that mercerised cotton accepts brighter, longer-lasting colours from less dye, while the treatment requires concentrated sodium hydroxide, washing and thermal energy.[S16] IFC guidelines describe the sequence: cotton reacts under tension with concentrated caustic soda, a hot-water wash removes bulk caustic, an acid bath neutralises remaining alkali, and rinses clear residual acid.[S01]
The physical chemistry behind downstream dye saving is documented in X-ray diffraction (XRD) and dyeing experiments on plain-woven cotton (160 g/m2, scoured and bleached).[S0502] Immersing cotton under tension in 250 g/L NaOH at 23 degrees Celsius for 3 minutes, washing twice at 60 to 70 degrees Celsius for 5 minutes, neutralising in 2 g/L HCl for 5 minutes and rinsing to neutrality swells the cell wall, converts native cellulose I into cellulose II, and lowers the XRD crystallinity index (CI) from 73.12 percent in original fabric to 63.19 percent (58.73 percent when caustic pre- and post-mercerisation are combined).[S0502] Because reactive dyes enter cotton through pores leading into amorphous regions, lower crystallinity and enlarged pore diameter boost dye sorption.[S0502]
Immersing cotton under tension in 250 g/L NaOH at 23 degrees Celsius for 3 minutes
S0502
In infrared dyeing (20:1 liquor ratio, 3 percent o.m.f. dye, 40 g/L NaCl and 10 g/L Na2CO3), caustic pre-mercerisation raised dye exhaustion (E%) to 85.1 percent for C.I. Reactive Red 2 (615.32 g/mol) and 65.5 percent for C.I. Reactive Red 195 (1,136.28 g/mol), while increasing fixation (F%) by 4 percent for both dyes and raising colour strength (K/S).[S0502] Pre-mercerisation in liquid ammonia at minus 40 degrees Celsius lowered crystallinity to 52.61 percent (cellulose III) but contracted pore diameter, restricting diffusion of C.I. Reactive Red 195 (56.6 percent exhaustion versus 65.5 percent for caustic) and lowering fixation.[S0502] Furthermore, caustic post-mercerisation applied after dyeing hydrolysed covalent ether bonds between reactive dye and cellulose, stripping 4.09 percent of fixed C.I. Reactive Red 2 from un-pre-mercerised cloth and 3.43 percent from caustic pre-mercerised cloth during 95 degrees Celsius washing (100:1 liquor ratio).[S0502]
While caustic pre-mercerisation reduces dyestuff needed for a target shade, its upstream burden is heavy.[S01][S03] The VTT review classifies mercerising as a high-water step requiring 232 to 308 L/kg of product when dilute caustic rinses are discharged without recovery, exceeding desizing (3 to 23 L/kg), scouring (23 to 43 L/kg) and bleaching (2 to 124 L/kg).[S03] IFC guidelines specify alkali recovery and reuse from mercerising effluent, and the VTT review highlights reusing mercerising effluent in scouring and bleaching baths.[S01][S03]
An engineering ledger cannot subtract saved grams of reactive dye from kilograms of sodium hydroxide, litres of wash water or megajoules of evaporator steam.[S02][S16] Quantities with different units (L of water, kg of NaOH, kg of acid, g of dye, MJ of heat and kWh of electricity) must be balanced in separate accounts per accepted kilogram before financial valuation applies tariffs.[S18][S29] Even within thermal energy alone, the analyst must trace where heat is added upstream and saved downstream (Exhibit 22).[S16][S03][S0502]
In the illustrative thermal ledger of Exhibit 22, a 100 kg woven cotton lot starts at an assumed unmercerised baseline of 1,850 megajoules (MJ, or 18.5 MJ/kg, within the 12 to 25 MJ/kg woven-finishing range in S01).[S01][S16] Caustic pre-mercerisation adds 420 MJ for hot washing at 60 to 70 degrees Celsius (S0502) and 310 MJ of evaporator steam to concentrate weak lye (S01, S16). Reusing warm alkaline wash water in scouring recovers 190 MJ (S03), while improved dye fixation cuts dyebath heat by 140 MJ (S0502) and lowers reprocessing heat by an illustrative 230 MJ (S37). The closing balance (1,850 + 420 + 310 - 190 - 140 - 230 = 2,020 MJ per 100 kg) shows a net increase of 170 MJ per 100 kg even after downstream colour gains and heat reuse are credited, proving why claiming a dyebath reduction without booking the mercerisation bay's steam, water and caustic ledgers is invalid.[S02][S16][S0502]
a 100 kg woven cotton lot starts at an assumed unmercerised baseline of 1,850…
S01, S16 · illustrative
Interlude · the cloth half-woven
Woven: sections 5.0 to 5.7Still to weave: 5.10 to 5.16
Read-out
Inherited sector context, not GFT output. Original publication dates were not recorded. The 2030 figure is a national target, not achieved production; the baseline is not a current verification.
Unit: percent of cotton fibre. Status: sourced. Sources: R06, R07.
Read this exhibit in its chapter ↗5.10
Wool scouring
Wool scouring: low 2, central 4, high 6 (litres per kilogram of product (L/kg)) · sourced
Loose fibre dyeing
Loose fibre dyeing: low 4, central 9.5, high 15 (litres per kilogram of product (L/kg)) · sourced
Loose fibre rinsing
Loose fibre rinsing: low 4, central 12, high 20 (litres per kilogram of product (L/kg)) · sourced
Yarn rinsing
Yarn rinsing: low 30, central 40, high 50 (litres per kilogram of product (L/kg)) · sourced
Woven fabric finishing
Woven fabric finishing: low 50, central 75, high 100 (litres per kilogram of product (L/kg)) · sourced
Yarn finishing
Yarn finishing: low 70, central 95, high 120 (litres per kilogram of product (L/kg)) · sourced
Knitted fabric finishing
Knitted fabric finishing: low 70, central 95, high 120 (litres per kilogram of product (L/kg)) · sourced
Sourced from IFC EHS Guidelines for Textile Manufacturing Table 3 (S01, citing European Commission 2003b). Midpoints are arithmetic centres of published low and high bounds. IFC notes that industry benchmarks originate from only a limited number of installations and are for comparative guidance only.
Unit: litres per kilogram of product (L/kg). Status: sourced. Sources: S01.
5.10 · the bodyExhibit 23 above; its figures are illustrative where marked.
Whether preparation runs in batch vessels, semi-continuous pad-batch stations or continuous ranges changes baseline water, steam and electricity per kilogram.[S01][S02][S16] In batch preparation, grey or greige cloth is loaded into a jet, overflow, winch, kier or beam machine and cycled through fills, heated holds and drains for desizing, scouring and bleaching.[S01][S02] Each drain loses sensible heat and requires fresh water to re-establish circulation, which in older winches and hank machines can exceed a 15:1 to 50:1 liquor ratio compared with 1:5 to 1:8 in modern low-liquor jet and overflow vessels.[S01][S02]
By contrast, continuous preparation feeds stitched webs through saturators, steamers and countercurrent washing boxes at 50 to 250 metres per minute.[S01][S02] IFC guidelines recommend three interventions: (1) combining scouring and bleaching into one step (or integrating desizing, scouring and bleaching with bleach-rinse reuse in desizing); (2) using continuous knit bleaching ranges instead of batch equipment where volume permits; and (3) applying mechanical dewatering ahead of stenters to reduce moisture and drying load.[S01][S17]
Experimental evidence confirms the potential of stage integration while highlighting its chemical boundaries.[S01][S0504] In the combinative pretreatment study on greige knitted cotton, merging scouring and peroxide bleaching into one 90 degrees Celsius bath for 60 minutes (followed by 15-minute in-bath cationisation with 30 g/L glycidyltrimethylammonium chloride and 3 g/L NaOH) eliminated intermediate drains and re-heats while achieving 77.04 whiteness, 2.48 second wetting time and 96.74 percent salt-free reactive dye fixation for C.I. Reactive Red 195.[S0504] However, adding the cationising reagent at the start of the bath failed because alkaline peroxide degraded the reaction, proving that combined baths have strict compatibility windows.[S0504] Continuous ranges achieve low intensity per kilogram only when run lengths amortise bath charging, steamer warm-up and flushing; on short orders, batch low-liquor or cold pad-batch routes can outperform an under-loaded continuous range.[S02][S17][S29]
Because fibre type, construction and machinery route alter process demand across wide intervals, comparing a mill's preparation and finishing intensity against one all-textile average is invalid.[S01][S02][S29] In Bangladesh surveys, the 18-factory PLOS study reported average groundwater intake of 164 L/kg and dyehouse water use of 136 L/kg (119 L/kg wastewater), while the World Bank study noted estimates up to 250 to 300 L/kg.[S04][S08] When IFC disaggregates consumption by processing category in Table 3 of its guidelines, operation-specific ranges diverge (Exhibit 23).[S01]
The intervals in Exhibit 23 show why operation-specific accounting is mandatory.[S01] In IFC Table 3, wool scouring uses 2 to 6 L/kg (0.3 kWh/kg electrical and 3.5 MJ/kg thermal), loose-fibre dyeing uses 4 to 15 L/kg plus 4 to 20 L/kg for rinsing (0.1 to 0.4 kWh/kg electrical and 4 to 14 MJ/kg thermal), and yarn dyeing uses 15 to 30 L/kg in dyeing plus 30 to 50 L/kg in rinsing (0.8 to 1.1 kWh/kg electrical and 13 to 16 MJ/kg thermal).[S01] Full yarn finishing spans 70 to 120 L/kg, woven-fabric finishing spans 50 to 100 L/kg (0.5 to 1.5 kWh/kg electrical and 30 to 70 MJ/kg thermal), and knitted-fabric finishing spans 70 to 120 L/kg (1 to 6 kWh/kg electrical and 10 to 60 MJ/kg thermal), with dyed woven finishing below 200 L/kg and Table 4 cotton wastewater benchmarks spanning 50 to 180 L/kg across fabric routes.[S01] IFC Table 3 Footnote a warns that these benchmarks come from a limited number of installations; evaluating desizing (3 to 23 L/kg in S03), scouring (23 to 43 L/kg in S03), bleaching (2 to 124 L/kg in S03) or mercerising (232 to 308 L/kg in S03) requires submeters on matched fabrics.[S01][S02][S03][S29]
5.13
Preparation is both the largest generator of organic chemical oxygen demand in a cotton mill and a primary source of reusable process water, provided piping segregates effluents by contamination profile at design stage.[S01][S02][S03] IFC lists countercurrent washing and direct reuse of preparation and finishing water among its core water-conservation recommendations.[S01] Mixing all preparation discharges into one drain destroys that potential.[S01][S02]
Post-desizing wash water carries degraded starch sugars, lubricants, waxes or synthetic sizes (BOD5 and COD representing 35 to 50 percent of mill organic load, up to 20,000 mg/L COD).[S01][S03] Routing that liquor into bleaching or dyeing would consume oxidants, foul heat exchangers and re-deposit size.[S01][S02] Instead, IFC and BAT guidance specify two pathways for desizing effluent: recovering water-soluble synthetic sizes (PVA, polyacrylates or CMC) by ultrafiltration, or routing enzymatic starch-desizing effluent to biological treatment.[S01][S02][S03] Conversely, later rinses after peroxide bleaching and hot washes after caustic mercerisation have low suspended solids and low polymer load, containing mainly alkalinity and heat.[S01][S03] Bleach rinse water can cascade into scouring or desizing, while alkaline mercerising rinse water can feed scouring and bleaching baths requiring caustic soda and heat, alongside heat recovery from continuous ranges to preheat makeup water.[S01][S03][S17]
Reusing preparation water without an analytical release gate risks trading a modest water saving for a severe colour-reprocessing failure.[S02][S37] Every recycled stream re-entering wet processing must pass four checks: hardness cations, catalytic transition metals, residual oxidants or alkalis, and restricted surfactant residues.[S01][S33][S37]
First, calcium and magnesium hardness in makeup or recycled water interacts with scouring soaps and reactive dyes.[S01][S37] In a full-factorial design-of-experiments study (3^2 design) on cotton dyed with red reactive dye at 5, 10 and 15 g/L across water hardness levels of 10, 40 and 70 degrees German hardness (dH), polynomial models showed that hardness and dye concentration strongly affected colour strength (K/S), lightness (L*) and colour difference, achieving right-first-time shade without reprocessing only at 10 degrees dH and 15 g/L dye.[S37] If preparation rinse water carrying calcium or magnesium extracted from cotton ash (S0501) is reused without hardness control, it shifts shade coordinates out of tolerance.[S37][S0501] Second, trace iron and copper ions washed from grey cloth or pipework catalyse radical decomposition of hydrogen peroxide during bleaching, causing oxycellulose tendering and strength loss.[S01][S0503] Third, any bleach rinse reused in enzymatic desizing or bioscouring must be cooled and neutralised so temperature and pH do not deactivate alpha-amylase (pH 5.5 to 6.5, 30 to 60 degrees Celsius, S0503) or pectate lyase (pH 5.0 to 5.5, 55 degrees Celsius, S0501), and water entering dyeing must be free of residual peroxide.[S0501][S0503]
5.16
Related · chapter 076 paragraphs step it
Read-out
Values reported in S0702 Table 7 for regular dark-shade (Black, 5 percent owf reactive dye, 80 g/L salt, 20 g/L soda ash) exhaustion dyeing and sequential post-dyeing wash-off stages on 160 g/m2 cotton knit fabric. Corresponding TDS falls from 9,780 to 1,150 mg/L and COD falls from 1,842 to 497 mg/L across the same five stages.
Unit: electrical conductivity (uS/cm). Status: sourced. Sources: S0702.
Read this exhibit in its chapter ↗In poorly instrumented dyehouses, the dyeing vessel is blamed for defects locked into the fabric during preparation.[S02][S37] When a batch exits dyeing with side-to-centre shading (listing), tailing, blotches or colour difference outside CIELAB tolerance, the production response is a shading addition, soap-off or strip-and-redye cycle.[S31][S37] Every corrective cycle consumes extra water, heat, electricity, chemicals and machine hours while producing zero additional accepted kilograms.[S37]
Even low-liquor dyeing machinery cannot compensate for an unlevel substrate.[S02][S36][S38] While EU BAT conclusions specify low-liquor-ratio batch dyeing (S38, 1:5 to 1:8 for cotton in rope form in S02), experimental work at a 1:6 liquor ratio shows that reactive dye fixation remains sensitive to dye structure and fibre accessibility, recording fixation rates of 84.9, 71.1 and 75.0 percent across three reactive yellow dyes (MRY-1, MRY-2 and MRY-3).[S02][S36][S38] Because a 1:6 bath has less liquid buffer per kilogram of cloth than a 1:15 bath, any residual starch, wax, peroxide or uneven mercerisation crystallinity (CI% variation in S0502) translates into spatial standard deviation of K/S colour strength across the fabric (20 random points per sample in S0502) and forces rework.[S36][S0501][S0502]
Before committing capital to new dyeing machines, GFT's engineering sequence tests whether tightening preparation control reduces dye-uptake variation and raises right-first-time (RFT) pass rates on existing vessels.[S18][S37] Paired trials compare baseline preparation against controlled preparation (verified amylase desizing, scouring weight loss within 3 to 6 percent, catalase peroxide elimination to 0 mg/L, neutral extract pH and wetting time below 3 seconds across left-centre-right swatches) on matched lots dyed with identical reactive recipes.[S37][S0501][S0503][S0504] Only after lifting the preparation ceiling can dyebath upgrades be measured cleanly.[S02][S18]
For GFT's Cameroon textile programme, linking preparation records to dyeing and garment records is an industrial-structure necessity.[R06][R07][S24] Cameroon's sector is working to move from its baseline of about 95 percent raw cotton fibre export and 5 percent local processing (in GFT's 31 January 2024 source base, R06) toward the 50 percent local-processing target by 2030 (R07), alongside announced national restructuring and integrated-project initiatives (R08, R09, R10, R12). In GFT's operating concept, cut-make-trim (CMT) and garment finishing sit at the core while upstream spinning, weaving, knitting and wet processing involve partnered mills or phased integration.[S24]
When a dyehouse receives greige or prepared fabric from a partner mill, or transfers lots between an internal preparation range and batch dye vessels, unlinked lot numbers break root-cause analysis.[S24][S37] If a dye lot fails RFT release and requires 80 L/kg of extra stripping and re-dyeing water, an unlinked database books the variance against the dyehouse shift, hiding the fact that a preparation roll entered with a 7.5 second wetting time on one selvedge or 12 mg/L of residual peroxide.[S37][S0501][S0503] Joining prep_lot_id to dye_lot_id in the batch spine lets weekly reviews regress RFT failure rates and K/S standard deviations against incoming wetting time, extract pH, residual peroxide and water hardness.[S18][S29][S37]
Check the record
Every knot is a source this chapter cites; select one to read its record, or filter the register by grade. Publication dates and inherited-source limits stay explicit. Read the paper's full evidence summary.
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R06 · Grade C · inherited record
Inherited evidence R06
About 95 percent of cotton fibre exported raw against 5 percent processed locally; industrialisation target of 50 percent local processing.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
R07 · Grade C · inherited record
Inherited evidence R07
SND30 restates the 50 percent local-processing target by 2030.
Publication date unrecorded. Inherited source-text record. The original publication has not been independently reopened for this web edition.
c05-S01 · Grade A
Environmental, Health, and Safety Guidelines for Textile Manufacturing
Water consumption in textile manufacturing has a significant environmental impact, in terms of freshwater needs, wastewater/sludge production, and energy used in heating.
2007-04-30. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S02 · Grade A
Best Available Techniques (BAT) Reference Document for the Textiles Industry
Important issues for the implementation of Directive 2010/75/EU in the textiles (TXT) sector are emissions to water and air, use and handling of chemicals as well as energy consumption.
2023. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S03 · Grade B
Textile production water use and textile wastewaters: Literature Review
Textile wet processes consume approximately 60 to 90 % of the total water used in textile processes.
2024-04-16. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S04 · Grade B
Water and chemical consumption in the textile processing industry of Bangladesh
The average groundwater consumption was 164 L/Kg; dyehouse water was 136 L/Kg, while the corresponding wastewater generated was 119 L/Kg.
2023-07-31. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S08 · Grade A
An analysis of industrial water use in Bangladesh with a focus on the textile and leather industries
According to IFC, the average factory water consumption in Bangladesh is estimated to be up to 250 to 300 litres of water per kilogram of fabric produced.
2015. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S16 · Grade B
Electrified Process Heating in Textile Wet-Processing Industry: A Techno-Economic Analysis for China, Japan, and Taiwan
Wet-processing preparation (de-sizing, bleaching, etc.), dyeing and printing, and finishing together demand the greatest share of thermal energy (50%).
2022-11-25. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S17 · Grade A
Improving Process Heating System Performance: A Sourcebook for Industry, Third Edition
A systems approach provides a tops-down review of the entire process and how the individual components perform and interact with each other.
2015. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S18 · Grade A
ISO 50001:2018 Energy management systems: Requirements with guidance for use
ISO 50001:2018 is an international standard that provides a framework for establishing, implementing, maintaining, and improving an Energy Management System (EnMS).
2018. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S24 · Grade B
Higg Facility Environmental Module (FEM) 4.0 Technical Paper
This means a facility that manufactures final finished products and fabric in the same facility will need to track and report their energy and water consumption data separately.
2022. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S29 · Grade B
Energy Efficiency Benchmark in Textile Manufacturing Companies
Specific energy consumption (SEC) is a widely used indicator of energy consumption per unit produced [2].
2021-06-28. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S31 · Grade B
Eco-friendly salt/alkali-free exhaustion dyeing of cotton fabric with reactive dyes
The characterization of effluent samples with RY 145 taken after dyeing using TNA compared with conventional dyeing indicated an efficient reduction of COD, BOD, and TDS values by 99, 97, and 97%, respectively.
2022-12-26. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S32 · Grade B
ZDHC MRSL V3.1 and Conformance Guidance V2.1: Formulator
Uploading Safety Data Sheets (SDS) for all ZDHC MRSL Conformant products is mandatory.
2023. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S33 · Grade B
ZDHC Wastewater Guidelines, Version 2.2
The purpose of testing ZDHC MRSL parameters is to check for intentional use of ZDHC MRSL substances and/or high levels of respective contamination in the chemical inputs.
2024. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S36 · Grade B
Exploring the requirements of reactive dyes in eco-friendly dyeing process: The relationship between dye structure, dyeing properties, and eco-friendly dyeing techniques
For low liquor ratio dyeing, when the liquor ratio was 1:6, the fixation rates of MRY-1, MRY-2, and MRY-3 were 84.9 %, 71.1 %, and 75.0 %, respectively.
2024. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S37 · Grade B
Right-first-time dyeing: a design of experiments approach for the optimisation of dyeing-processes using hard water
The benefits of achieving the right-first-time are very significant including for instance, reduction in water and energy consumption, reduction in effluent generation along with time and colour saving (Parton, 1994).
2019. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S38 · Grade A
Commission Implementing Decision (EU) 2022/2508 of 9 December 2022 establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for the textiles industry
Batch processes are carried out with low-liquor-ratio systems (see Section 1.9.4).
2022-12-09. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S0501 · Grade B
Eco-friendly scouring of cotton knit fabrics with enzyme and soapnut: An alternative to conventional NaOH and synthetic surfactant based scouring
The presence of non-cellulosic matters like pectins, waxes, lipids, proteins, etc. in the outermost layer of cotton fiber works as a shield against a rough environment and at the same time hinders the wettability and absorbency of it during subsequent processing due to those hydrophobic substances [1].
2023-04-05. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S0502 · Grade B
Combination of Pre- and Post-Mercerization Processes for Cotton Fabric
Through mercerization, the crystallinity of the cotton fiber decreases and the amorphous characteristics increase, producing more pores and effective hydroxyl groups in the fiber, which is beneficial for dye exhaustion [12] and fixation [13,14], leading to improved dyeability [10].
2022-03-11. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S0503 · Grade B
The Shift to Bio-Based Auxiliaries in Textile Wet Processing: Recent Advances and Industrial Potential
To mitigate this, catalase is increasingly used to decompose residual H2O2 into water and oxygen, reducing the need for intensive rinsing, saving water and energy, and lowering H2O2 levels in resulting effluents [12].
2025-10-08. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c05-S0504 · Grade B
Combinative Scouring, Bleaching, and Cationization Pretreatment of Greige Knitted Cotton Fabrics for Facilely Achieving Salt-Free Reactive Dyeing
In addition, the average diffusion time of water droplet was 2.48 s, which satisfied the requirement of less than 3 s in GBT 21655.1-2008.
2017-12-18. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗S02 European Commission Joint Research Centre. 2023.
S37 Emerald Publishing Limited. 2019.
S01 International Finance Corporation, World Bank Group. 2007-04-30.
S0501 Elsevier, Heliyon. 2023-04-05.
S0504 MDPI, Molecules. 2017-12-18.
S03 VTT Technical Research Centre of Finland, Telaketju. 2024-04-16.
S16 MDPI, Energies. 2022-11-25.
S0503 MDPI, Molecules. 2025-10-08.
R06 Cameroon Trade Hub. Publication date unrecorded; inherited source-text check.
R07 Ecofin Agency. Publication date unrecorded; inherited source-text check.
S24 Sustainable Apparel Coalition. 2022.
S29 Sciendo, Riga Technical University, Environmental and Climate Technologies. 2021-06-28.
S18 International Organization for Standardization. 2018.
S31 Springer Nature, Scientific Reports. 2022-12-26.
S0502 MDPI, Materials. 2022-03-11.
S17 United States Department of Energy and Industrial Heating Equipment Association. 2015.
S04 PLOS Sustainability and Transformation. 2023-07-31.
S08 2030 Water Resources Group, World Bank. 2015.
S33 ZDHC Foundation. 2024.
S32 ZDHC Foundation. 2023.
S36 Elsevier, Dyes and Pigments. 2024.
S38 European Commission. 2022-12-09.
Keep the thread · chapter 05 of 14
Move the shuttle along the rack to preview any chapter: its sections, exhibits and reading time. Draft web edition. This research is not investment, legal or tax advice; illustrative models are not measured factory results.
The paper's rack · 14 boltsBolt length: reading time
01Part I: Define the unit before reducing it
Adding value inside Cameroon requires an explicit account of the water, chemistry and energy associated with accepted production, including the work bought from suppliers.
02Part I: Define the unit before reducing it
A per-unit ratio is meaningful only when output, quality release, product mix and allocation rules remain visible beside it.
03Part I: Define the unit before reducing it
Volumetric accounting becomes decision-ready only when source, catchment, season, quality and discharge are attached to each litre.
04Part I: Define the unit before reducing it
A shade is resource-efficient only when its accepted result includes the chemistry, washing, corrections and discharge needed to produce it.
05Part II: The process sets the floor
Uneven or incomplete preparation propagates extra water, heat and correction through every later stage.
06Part II: The process sets the floor
A smaller nominal bath is an engineering opportunity whose real value depends on levelness, fixation, rinsing, throughput and reprocessing.
07Part II: The process sets the floor
The correct rinse is the minimum flow that reaches the specified residual-chemistry endpoint with acceptable colour and fabric quality.
08Part II: The process sets the floor
Removing liquid before evaporation can reduce the drying duty, provided that fabric quality, finish chemistry and accepted output remain inside the test.
09Part II: The process sets the floor
A garment plant may avoid a dyehouse on site, but it still needs a per-piece account for machines, utilities, washing and every unit that fails first time.
10Part III: Reduction is a system
A reuse system is a production process with its own energy, chemistry, losses and quality release, not a free source of water.
11Part III: Reduction is a system
A recovery or electrification project earns its place only when a measured source can serve a measured sink at the required time, temperature and emissions factor.
12Part III: Reduction is a system
A resource project is ready for capital only when its baseline, production effect and whole-cycle savings are measured with enough confidence to survive operating variance.
13Part IV: GFT's measurement and reduction system
Resource data becomes useful when it carries the identity of the fabric, recipe, machine and quality decision that produced it.
14Part IV: GFT’s measurement and reduction system
GFT recommends a sequence of evidence gates, from a signed measurement contract to repeated operating proof, with scale conditional on resource, quality and environmental performance.