Research libraryWater, Dye and Energy per Unit
Chapter 10 of 14 · Part III · Draft web edition
A reuse system is a production process with its own energy, chemistry, losses and quality release, not a free source of water.
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
Illustrative GFT heuristic informed by the cited sources, not measured performance. X: 0 to 2 cascade or screening, 3 to 5 clarification or filtration, 6 to 8 oxidation or UF, 9 to 10 RO and polishing. Y: 0 to 2 no product contact, 3 to 5 upstream wash, 6 to 8 equipment or final rinse, 9 to 10 critical dyeing or pastel work. Integer positions require site validation.
Unit: illustrative screening score (0 to 10). Status: illustrative. Sources: S01, S02, S37, S1002. Illustrative figures are teaching examples, not measured factory results.
Overture · 1 min
Water reuse reduces a textile factory's net environmental burden only when each recovered stream is segregated, matched to its receiving operation, and credited after treatment electricity, chemicals, concentrate, sludge and quality-induced reprocessing.[S01][S06] Under-treatment can introduce hardness, alkalinity, salt or colour into sensitive dye baths and cause corrective work. Over-treating every stream through ozonation and reverse osmosis adds electricity demand and a saline reject.[S02][S06][S37][S1001] For GFT's Cameroon textile programme, moving wet processing onshore makes water circulation a controlled manufacturing stage. The inherited sector baseline records about 95 percent of cotton fibre exported raw and 5 percent processed locally, with a national target of 50 percent local processing by 2030.[R06][R07] This chapter defines the required segregation, quality release, mass and energy balances, residual governance and sampling before comparing partial reuse with zero liquid discharge. It is an engineering framework, not legal, regulatory or investment advice.
10.1
A textile wet-processing plant discharges distinct process liquors whose volume, temperature, organic load, salinity and chemical toxicity can vary substantially by process and operating sequence.[S01][S02] In the literature review compiled by VTT, wet processes account for 60 to 90 percent of total textile water use.[S03] When floor drains empty into one equalisation basin, low-salinity cooling water and final rinses are contaminated by spent reactive dyebaths, desizing liquors and mercerising caustic washes, forcing the treatment plant to address the combined contaminant profile.[S01][S02][S1003]
wet processes account for 60 to 90 percent of total textile water use
S03
IFC's environmental, health and safety guidelines for textile manufacturing place source segregation at the front of wastewater design, distinguishing chemical oxidation for non-biodegradable high-load chemical oxygen demand (COD) streams, chemical precipitation, coagulation and flocculation for heavy-metal streams, and reverse osmosis for highly coloured or high total dissolved solids (TDS) streams.[S01] The same logic applies inside preparation and dyeing halls.[S02][S38] Desizing effluents carry biochemical oxygen demand (BOD5) and COD loads representing 35 to 50 percent of a composite mill's organic load, with COD concentrations reaching up to 20,000 milligrams per litre when starch, modified starch or synthetic sizes are stripped from grey fabric.[S01] Mixing that concentrated stream with clean cooling water or bleach rinses can compromise recovery. Ultrafiltration can recover suitable polyvinyl alcohol or carboxymethyl cellulose formulations, but the BAT reference excludes some synthetic sizes, including certain polyacrylates, so recovery requires formulation-specific validation.[S01][S02]
Segregation begins with a drain-level manifold separating four classes at the machine boundary:[S01][S02] 1. Non-contact utility streams: Compressor cooling, stenter cooling rollers and indirect heat-exchanger water pick up sensible heat without chemical contamination and return directly to warm process makeup tanks after temperature and conductivity checks.[S01] 2. Low-contamination wash and rinse fractions: Later compartments of countercurrent washing ranges and final peroxide-bleach rinses cascade backward into upstream desizing or initial scouring baths without membrane desalination.[S01][S38] 3. High-alkali mercerising washes: Cotton treated with concentrated sodium hydroxide generates hot alkaline rinse water suitable for evaporative or membrane alkali recovery, subject to colour checks on yarn-dyed cloth.[S01] 4. High-salt and high-colour dyehouse drains: Spent reactive and disperse dyebaths, printing-belt wash waters and initial soap-off baths carry unfixed dye and electrolytes requiring dedicated treatment.[S01][S31]
In cotton batch dyeing with reactive dyes, salt additions range from 20 to 80 percent of fabric weight, producing dyebath effluent salt concentrations of 2,000 to 3,000 parts per million alongside COD values often above 5,000 milligrams per litre.[S01] Laboratory characterisation of conventional reactive yellow dyeing on cotton confirms that high electrolyte and alkali dosing drives elevated effluent TDS, COD and BOD loads unless salt-free or low-salt chemistries are validated.[S31] Because biological treatment and ultrafiltration leave dissolved salts untouched, high-salinity dyebath drains determine whether reverse osmosis or evaporation is needed for closed-loop recycling.[S06][S1001] Segregating saline drains from low-salt preparation and final rinses confines energy-intensive desalination to the fraction requiring salt rejection.[S01][S02]
Physical segregation must be paired with accounting segregation. Higg FEM technical guidance requires any site manufacturing both fabric and finished garments to track and report energy and water consumption separately by facility type.[S24] Each segregated header therefore requires its own flow meter, conductivity probe and batch-linked diversion valve so operators can trace any rise in membrane inlet conductivity to the exact machine drain.[S18][S24][S1002]
10.2
Exhibit 446 paragraphs step it
Read-out
| Desizing & grey wash | Bleach/final rinse cascade + fine screen | SS, pH, residual oxidant, temperature | Reuse bleach rinse in desizing (S01) | Enzyme deactivation or lint redeposition |
|---|---|---|---|---|
| Mercerising wash & caustic makeup | Segregated mercerising rinse + evaporation/NF | NaOH concentration, colour, suspended fibres | Alkali recovery subject to colour limit (S01) | Shade staining on yarn-dyed woven cloth |
| Reactive dyeing & pastel bleaching | Bio + O3/UF + RO permeate (plus softening) | Hardness, colour, conductivity, Fe/Mn, pH | Foshan mean primary/secondary RO: CODcr 0.37/0.44 mg/L; hardness 22.04/3.45 mg/L (S06) | Dye precipitation, ΔE failure, catalytic fibre damage |
| Post-dye countercurrent rinsing | Cascaded later rinses or UF/RO blend | Conductivity, residual colour, total alkalinity | FZ/T 01107-2011 RO reuse: conductivity <=2.5 mS/cm, chroma <=25 (S1002) | Poor wash fastness or back-staining of ground shade |
| Cooling & utility makeup | Segregated non-contact cooling or RO permeate | Hardness, silica, chloride, microbiological activity | Historical GB/T 19923-2005 in Foshan: Cl- <=250 mg/L, hardness <=450 mg/L (S06) | Heat-exchanger scaling, biofouling or corrosion |
Derived control framework from S01, S02, S06/S1001, S37 and S1002. Foshan values are reported averages for two different permeate streams, not limits or observed ranges. FZ/T 01107-2011 values in S1002 are RO-permeate reuse thresholds, not duty-specific site release limits. GB/T 19923-2005 values are historical benchmarks in the 2019 Foshan study; verify the currently applicable edition and local duties before use. Site limits require paired product trials.
Unit: candidate controls and source benchmarks. Status: derived. Sources: S01, S02, S06, S37, S1001, S1002.
Recycling water inside a textile mill is an input-quality decision governed by the receiving process, not a waste-disposal target governed by the treatment plant.[S02][S37] Reclaimed water satisfying a national discharge standard can still cause immediate production failure if routed to an incompatible wet-processing duty, because multivalent cations, residual oxidants, carbonate alkalinity, chromophores and salts interact directly with dye molecules and cellulose functional groups.[S06][S31][S37] Evaluating reuse by volumetric recovery while ignoring exhaustion, fixation, shade reproducibility and scaling violates the whole-cycle boundary of this paper.[S36][S37]
Right-first-time dyeing research demonstrates the empirical sensitivity of cotton dyeing to water quality.[S37] In hard water, dissolved calcium and magnesium ions can form precipitates and dye aggregates.[S37] Across experimental water hardness levels of 10, 40 and 70 German degrees of hardness, higher hardness reduced colour strength and altered lightness, shade and total colour difference in the tested reactive-dye system. Whitish deposits were proposed as an explanatory mechanism, not measured as a separate outcome.[S37] A batch missing its target shade may require shading additions, stripping or full re-dyeing, consuming extra water, thermal energy, auxiliaries and machine time while generating additional effluent.[S37] If a reuse loop saves 30 percent of fresh intake on paper but reduces right-first-time performance, the extra resource load of re-dyed batches must be debited against the reuse account.[S02][S37]
Water quality matching therefore requires a multi-parameter release gate tailored to each receiving operation.[S01][S02] Membrane-reuse research on pre-treated textile dyeing wastewater in China illustrates the treatment duty between membrane-bioreactor effluent and a cited reverse-osmosis permeate standard.[S1002] The feed had pH 8.52, COD 80 milligrams per litre, total organic carbon 12 milligrams per litre, suspended solids 0 milligrams per litre, chroma 95 dilution times, iron 0.27 milligrams per litre, manganese 0.06 milligrams per litre, total hardness 422 milligrams per litre as calcium carbonate, and conductivity 8.82 millisiemens per centimetre.[S1002] The cited Chinese textile reuse standard for reverse-osmosis permeate required pH 6.5 to 8.5, COD at or below 50 milligrams per litre, suspended solids at or below 30 milligrams per litre, chroma at or below 25 dilution times, iron at or below 0.3 milligrams per litre, manganese at or below 0.2 milligrams per litre, total hardness at or below 450 milligrams per litre as calcium carbonate, and conductivity at or below 2.5 millisiemens per centimetre.[S1002] Thus COD, chroma and conductivity required substantial removal, while the feed already met the listed hardness, suspended-solids, iron and manganese limits. This comparison defines an RO treatment duty, not a discharge violation.[S1002]
Compliance with that general envelope still does not prove suitability for a critical shade. The feed hardness of 422 milligrams per litre sits below the general RO-permeate ceiling of 450, but the BAT reference recommends no more than 90 milligrams per litre as calcium carbonate for high-quality recycled effluent.[S02][S1002] S37 also found hardness-dependent shade effects in one reactive-dye system. Receiving limits should therefore be established by paired fabric and dye trials, with softening or sequestering evaluated where necessary.[S37] Exhibit 43 offers an illustrative screening matrix, not a measured ranking, for matching treatment barriers to downstream shade and equipment sensitivity.[S01][S02][S37][S1002]
Duties in the lower-left quadrant, such as desizing and initial grey-fabric washing, may accept countercurrent bleach-rinse water after lint screening and control of residual oxidant, subject to the actual size recipe.[S01][S02] Duties in the upper-right quadrant, notably reactive dyebaths, optical brightening, pastel bleaching and final soft-water rinses, require strict control of hardness, iron, manganese, colour, alkalinity and conductivity.[S06][S37][S1002] Routing partially treated effluent into the upper-left quadrant creates rework risk, whereas routing high-purity reverse-osmosis permeate to floor washing can waste pump and ozone electricity on a less sensitive duty.[S06][S1001] Exhibit 44 converts the screening logic into candidate controls and source benchmarks. It is not a validated site specification.[S01][S06][S37][S1001][S1002]
In the Foshan case study, the cited national reuse standard permitted CODcr up to 60 milligrams per litre, colour up to 30 dilution times, hardness up to 450 milligrams per litre and chloride and sulphate up to 250 milligrams per litre each. Reported average primary and secondary reverse-osmosis permeate values were CODcr 0.37 and 0.44 milligrams per litre, colour 0.33 and 0.32 dilution times, hardness 22.04 and 3.45 milligrams per litre, and conductivity 415.84 and 288.60 microsiemens per centimetre.[S06][S1001] These averages met the cited standard and show substantial hardness and salt removal. They do not prove suitability for every sensitive dye process. GFT's proposed batch ledger therefore requires reuse-tank quality at every dyebath fill and product-specific release trials.[S06][S31][S37]
10.3
Bio-treated feed (75,000 m3/d)
Bio-treated feed (75,000 m3/d). Starting point. Leads to Stage 1 O3, UF and RO (75,000 m3/d). · derived
A wastewater reuse plant is a multi-stage separation process whose performance cannot be summarised by a single recovery percentage.
Stage 1 O3, UF and RO
Stage 1 O3, UF and RO. From Bio-treated feed (75,000 m3/d) (75,000 m3/d). Leads to Reused permeate (65,100 m3/d; 86.8%) (Primary permeate 50,250), Stage 2 O3, UF and RO (Primary concentrate 24,750), PAC sludge (balance unresolved) (Solids separated). · derived
Stage 2 O3, UF and RO
Stage 2 O3, UF and RO. From Stage 1 O3, UF and RO (Primary concentrate 24,750). Leads to Reused permeate (65,100 m3/d; 86.8%) (Secondary permeate 14,850), Biochemical-treatment return (Unrecovered RO flow 9,900 (derived)), Biochemical-treatment return (Cleaning returns 1,230 (internal)). · derived
Reused permeate (65,100 m3/d; 86.8%)
Reused permeate (65,100 m3/d; 86.8%). From Stage 1 O3, UF and RO (Primary permeate 50,250), Stage 2 O3, UF and RO (Secondary permeate 14,850). End point. · derived
Biochemical-treatment return
Biochemical-treatment return. From Stage 2 O3, UF and RO (Unrecovered RO flow 9,900 (derived)), Stage 2 O3, UF and RO (Cleaning returns 1,230 (internal)). End point. · derived
PAC sludge (balance unresolved)
PAC sludge (balance unresolved). From Stage 1 O3, UF and RO (Solids separated). End point. · derived
The method behind it: Method.
S06 and S1001 are copies of one study. RO balance: 75,000 = 50,250 + 24,750 and 24,750 = 14,850 + 9,900 m3/d. Permeate total is 65,100 m3/d (86.8%); 9,900 is derived by difference, not a metered discharge. Cleaning returns total 3,210 m3/d: 1,500 within Stage 1, 480 to the RO tank and 1,230 to biochemical treatment. Internal returns are not terminal losses. PAC sludge balance remains unresolved.
Unit: cubic metres per day (m3/d). Status: derived. Sources: S06, S1001.
10.3 · the bodyExhibit 45 above; its figures are illustrative where marked.
A wastewater reuse plant is a multi-stage separation process whose performance cannot be summarised by a single recovery percentage.[S06][S1001] Every unit operation requires chemical or electrical inputs, rejects a side stream or backwash flow, and alters the water passing to the next barrier, so GFT decomposes any headline recovery claim into a closed mass, energy and chemical balance.[S04][S06][S1001][S1003]
The full-scale Foshan study treated 75,000 cubic metres per day of biologically treated effluent, operating 24 hours per day.[S06][S1001] Stage 1 used polymeric aluminium chloride (PAC) at 80 grams per cubic metre, tube settling, sand filtration, ozonation at 80 to 100 grams per cubic metre (average 90), ultrafiltration below 0.15 megapascals and reverse osmosis at 1.0 to 1.2 megapascals.[S1001] Stage 2 treated 24,750 cubic metres per day of primary concentrate, with average conductivity of 28,236 microsiemens per centimetre, through ozonation at 100 to 120 grams per cubic metre (average 118), filtration, ultrafiltration and reverse osmosis at 1.5 to 2.5 megapascals (Exhibit 45).[S06][S1001] This is one documented train, not a design template.
The full-scale Foshan study treated 75,000 cubic metres per day of biologically treated effluent
S06, S1001
Inspecting the flow diagram reveals three engineering realities that an 86.8 percent headline omits.[S06][S1001] First, each barrier performs a distinct separation job. Coagulation, precipitation, sand filtration and primary ozonation removed 99.34 percent of suspended solids, 74.01 percent of colour and 39.85 percent of CODcr, protecting downstream membranes.[S1001] Primary ultrafiltration removed 52.18 percent of remaining turbidity and 17.34 percent of CODcr, yet had little effect on hardness, alkalinity, chloride, sulphate or conductivity.[S1001] Only across the reverse-osmosis membranes did conductivity fall by 92.94 percent in Stage 1 (two-year-old membranes) and 97.99 percent in Stage 2 (new membranes), with sulphate removals above 99 percent and chloride removals of 92.02 and 96.34 percent.[S1001] Ultrafiltration reduces suspended particles and macromolecular material but leaves nearly all dissolved salts and hardness in its permeate. Salt-sensitive reuse therefore needs additional desalination or softening.[S1001]
Second, cleaning streams follow different return paths. Primary and secondary sand-filter backwash of 1,500 cubic metres per day returned within Stage 1 after precipitation and re-filtration. Primary ultrafiltration backwash of 350 and primary reverse-osmosis wash of 130 cubic metres per day returned to the RO tank. Third-sand backwash of 750, secondary ultrafiltration backwash of 130 and secondary reverse-osmosis wash of 350 cubic metres per day returned to biochemical treatment, giving 3,210 cubic metres per day of internal cleaning flows rather than terminal losses.[S1001] Table 6 reports 6,098 kilograms per day of PAC and 234.65 kilograms per day of anti-scalant, reducing and sterilising agents. The nominal PAC dose on 75,000 cubic metres per day instead gives 6,000 kilograms per day, leaving an unreconciled 98-kilogram difference in the source's presentation.[S1001]
Third, membrane permeability and salt rejection depend on cleaning conditions.[S1001][S1002] In Foshan, the economic model replaced ultrafiltration membranes every five years (1,224 elements) and reverse-osmosis membranes every three years (5,280 elements).[S1001] In a separate laboratory study at 60 percent recovery, permeability declined by more than 15 percent after 625 litres of permeate per square metre. The authors explicitly limit that cleaning threshold to the tested membrane, feed and operating conditions.[S1002] Combined acid and alkaline forward flushing restored specific flux to 87 percent of a new membrane. Adding pure-water backwashing at 0.125 megapascals and 0.5 metres per second restored 96 percent without measured rejection damage, whereas intensive backwashing at 0.5 megapascals and 1.5 metres per second degraded rejection. The preliminary chemical cost was 0.763 Chinese yuan per cubic metre of RO production, based on 750 litres per square metre before cleaning, not a universal full-cleaning cost.[S1002]
Interlude · the cloth half-woven
Woven: sections 10.0 to 10.3Still to weave: 10.4 to 10.6
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 ↗10.4
Gross RO permeate
Gross RO permeate: total 1,000. Running total 1,000 illustrative cubic metres per day (m3/d) · illustrative
High-recovery water reuse trades reduced freshwater intake for electrical power, chemical reagents, membrane consumables and a concentrated residual stream.
Unreturned backwash
Unreturned backwash: removes 60. Running total 940 illustrative cubic metres per day (m3/d) · illustrative
CIP & flush losses
CIP & flush losses: removes 25. Running total 915 illustrative cubic metres per day (m3/d) · illustrative
Re-dyeing water penalty
Re-dyeing water penalty: removes 85. Running total 830 illustrative cubic metres per day (m3/d) · illustrative
Net freshwater displaced
Net freshwater displaced: total 830. Running total 830 illustrative cubic metres per day (m3/d) · illustrative
The method behind it: Worked example: Multi-ledger reconciliation of an illustrative dyehouse reuse loop.
Illustrative one-pass reconciliation. From 1,000 m3/d gross permeate, deduct 60 backwash, 25 cleaning losses and 85 additional re-dye demand, giving 830 m3/d net freshwater displaced. Cleaning flows are drawn from permeate; the re-dye penalty assumes 500 kg at 170 L/kg. Not a closed facility balance: re-dye effluent, dewatering filtrate, sludge moisture and evaporation need separate assignment. Other resources stay in parallel ledgers.
Unit: illustrative cubic metres per day (m3/d). Status: illustrative. Sources: S06, S37, S1001. Illustrative figures are teaching examples, not measured factory results.
10.4 · the bodyExhibit 47 above; its figures are illustrative where marked.
High-recovery water reuse trades reduced freshwater intake for electrical power, chemical reagents, membrane consumables and a concentrated residual stream.[S06][S1001][S1003] Reporting only the reduction in cubic metres of water withdrawn conceals burden shifting across environmental categories.[S10][S20] In GFT's accounting architecture, a reuse system is evaluated as an energy-consuming utility and a concentrate generator simultaneously.[S18][S24]
The Foshan dataset quantifies the operating economics of advanced reuse.[S06][S1001] Across 65,100 cubic metres per day of reclaimed water, reported operating cost was 0.44 US dollars per cubic metre at an electricity tariff of 0.10 US dollars per kilowatt hour.[S1001] Rounded components were 0.19 for sand filtration, ultrafiltration and reverse osmosis, 0.18 for ozone production, and 0.08 for maintenance, salaries, PAC and chemical agents.[S1001] RO pump electricity and membrane replacement were reported at 0.11 and 0.04 US dollars per cubic metre respectively, with ultrafiltration at 0.04. Electricity for ozonation and RO accounted for 64.84 percent of total operating cost (Exhibit 46).[S06][S1001]
Table 6 of the Foshan study shows the rising marginal energy penalty as recovery increases from 67.0 percent in Stage 1 to 86.8 percent across both stages.[S1001] Reclaiming 50,250 cubic metres per day in Stage 1 required 81,000 kilowatt hours per day for ozone and oxygen generation plus 60,288 kilowatt hours per day for pumps, totalling 141,288 kilowatt hours per day, or 2.81 kilowatt hours per cubic metre of primary permeate.[S1001] Reclaiming 14,850 cubic metres per day from primary concentrate required 35,046 kilowatt hours per day for ozone plus 21,384 kilowatt hours per day for pumps, totalling 56,430 kilowatt hours per day, or 3.80 kilowatt hours per cubic metre of secondary permeate. Secondary electricity intensity was about 35 percent higher.[S1001] The source separately reports total secondary unit operating cost as 0.086 US dollars per cubic metre higher than primary cost; that is not an electricity-only difference.[S1001] Combined treatment electricity reached 197,718 kilowatt hours per day, or 3.04 kilowatt hours per cubic metre. These figures cover the post-biological reuse train, not biological treatment, final brine disposal or ZLD.[S1001]
Table 6 of the Foshan study shows the rising marginal energy penalty as recovery…
S1001
In Cameroon, power-sector reform is ongoing under a World Bank programme approved in August 2023, but neither grid reliability nor a low grid emissions factor can be assumed without site measurement.[S25] A train with electricity intensity near the Foshan value would add about 3 kilowatt hours per cubic metre of recycled water before final brine management.[S1001] Under ISO 50001 and GHG Protocol Scope 2 rules, electricity drawn by ozone generators and membrane pumps enters the factory's energy baseline and indirect emissions inventory. Captive diesel fallback during interruptions would also affect cost and emissions per accepted kilogram.[S16][S18][S19]
Equally critical is the fate of reverse-osmosis concentrate and chemical sludge.[S01][S06][S33] Reverse osmosis concentrates dissolved salts and refractory organics into the reject stream.[S06][S1001] Without a salt purge or another outlet, recycled concentrate can increase loop salinity, inhibit biological treatment and raise osmotic pressure and required membrane feed pressure.[S06][S1001][S1003] Coagulation and biological treatment also generate 1 to 5 kilograms of dewatered sludge per cubic metre of treated wastewater.[S01] Internal recycling can reduce blue-water withdrawal, but pollutants remain in a smaller, more concentrated discharge or in solid waste unless they are destroyed or lawfully recovered. Recycling is not pollutant elimination.[S10][S33] Exhibit 47 and the worked example reconcile these flows in parallel physical ledgers.[S06][S37][S1001]
10.5
Related · chapter 036 paragraphs step it
Read-out
Structured screening placement derived from S12 (national vs basin stress), S13 (industrial wastewater under-reporting), S14 (Ethiopian textile groundwater dependence and pollution risk exceeding quantity risk), S15 (Douala potable-water and drainage deficits), S0301 (WRI Aqueduct 4.0 textile weights) and S0302 (AWS Standard 2.0 site-catchment scope). Site-specific measurements must replace screening scores before investment.
Unit: structured risk-screening score (0 to 10 scale). Status: sourced. Sources: S12, S13, S14, S15, S0301, S0302.
Read this exhibit in its chapter ↗A water-reuse and effluent-control system is only as credible as its sampling protocol.[S13][S33] In a batch dyehouse, pollutant concentrations, temperature, pH and salinity vary as machines drain scouring baths, salty reactive dyebaths, soap-off washes or dilute rinses.[S01][S02] A grab sample taken during a final rinse can make an inadequate plant appear compliant, while an uncalibrated inline conductivity probe can let a slug of hard permeate into the dyehouse header.[S33][S1002] UN-Water's 2024 assessment of Sustainable Development Goal Indicator 6.3.1 warns that global estimation of total and industrial wastewater flows remains impossible due to widespread under-reporting, and emphasises that treatment figures require explicit disclosure of data coverage, flow basis and monitoring methods.[S13] At the factory level, GFT applies the same rule: no reuse quality figure or effluent concentration enters the batch ledger without its sampling method, flow-weighting basis, analytical standard and coverage period.[S13][S33]
The ZDHC Wastewater Guidelines (Version 2.2) link sampling locations and parameter lists to chemical-input governance and discharge configuration.[S33] Full wastewater testing applies at or above an average industrial wastewater threshold of 15 cubic metres per day (annual industrial wastewater discharged divided by working days per year across wet processing, printing, laundry and washing).[S33] Qualifying facilities sample across two semi-annual cycles (October and April) across three locations depending on archetype: Untreated Wastewater (prior to any treatment), Discharged Wastewater (treated direct-discharge effluent or pretreated indirect effluent), and Sludge (residuals from primary, secondary and tertiary or zero-liquid-discharge operations).[S33]
Crucially, ZDHC requires Manufacturing Restricted Substances List (MRSL) parameters to be sampled and tested in untreated wastewater only. Listed heavy metals are tested in discharged effluent where applicable, but an indirect-discharge facility without pretreatment tests them in untreated wastewater because no treatment step exists.[S33] Testing untreated water checks for intentional use of restricted substances or input contamination before dilution, sludge sorption or oxidation can mask their presence.[S33] An MRSL non-conformity, including a sludge result above the applicable reporting limit, triggers Root Cause Analysis and a Corrective Action Plan directed at the chemical inventory and supplier Safety Data Sheets.[S32][S33]
For conventional parameters and anions in direct-discharge facilities (Foundational, Progressive and Aspirational tiers), composite sampling must be paired with on-site hourly measurements for pH, temperature difference, persistent foam, flow rate, total chlorine and dissolved oxygen.[S33] While total suspended solids (textile limits of 50, 15 and 5 milligrams per litre) and total phosphorus (3, 0.5 and 0.1 milligrams per litre) carry numerical ceilings, ZDHC classifies total dissolved solids (TDS), chloride and sulphate as "Sample and Report only" parameters (SM 2540-C and ISO 10304-1 or ISO 15923-1).[S33] In a reuse loop, "Sample and Report" on TDS, chloride and sulphate is an operational red flag: because biological treatment does not remove chloride or sulphate, tracking their mass balance across untreated intake, permeate and concentrate is the primary check on salt accumulation and membrane integrity.[S06][S33][S1001]
Sludge sampling completes the mass balance, but ZDHC requirements depend on the disposal pathway.[S01][S33] Pathways A to C have no testing requirement for pathway approval, although MRSL testing still supports input-chemistry corrective action. Pathways D and E require pH, percentage solids, paint-filter free liquids and cyanide tests; F and G add faecal coliform, with metals and leachate rules applied as specified.[S33] At 5 percent solids or less, dewatering or drying is expected before transport, except where local law permits safe transport of liquid sludge to an external agency for treatment or disposal without environmental impact.[S33] The site must record the pathway, applicable tests and actual solids content rather than apply one test list to every load. IFC's separate benchmark of 1 to 5 kilograms of dewatered sludge per cubic metre provides a mass-accounting cross-check.[S01][S33]
10.6
Zero liquid discharge (ZLD) is one boundary configuration among ZDHC's wastewater archetypes, and its merit depends on local hydrology, receiving-water conditions, energy supply and residual-solids management.[S02][S33][S1003] Under the ZDHC Wastewater Guidelines, ZLD means no industrial wastewater is discharged from the site in liquid form to the environment. Any such discharge, including recycled wastewater used for gardening or grounds irrigation, disqualifies ZLD status.[S33] ZDHC Table A requires ZLD facilities to test untreated wastewater for all MRSL parameters and to manage sludge and crystalliser residuals under the applicable disposal-pathway rules.[S33]
In Foshan, two reverse-osmosis stages recovered 86.8 percent of the 75,000 cubic metres per day inflow at 3.04 kilowatt hours and 0.44 US dollars per cubic metre. The simplified balance leaves 9,900 cubic metres per day (13.2 percent) unrecovered, derived by difference and returned to biochemical treatment in the documented configuration rather than proven as an environmental discharge.[S06][S1001] The residual fraction in another system depends on its membranes and recycle configuration. Closing the liquid gap may require additional brine concentration, evaporation, crystallisation or another verified no-liquid-discharge arrangement.[S01][S1003] Recovered salts and solids require characterisation and a lawful recovery or disposal pathway. Hazardous-waste containment applies only where composition, testing and local law require it, not merely because the solids came from a ZLD train.[S33][S1003]
Linking this circulation framework to GFT's digital spine would keep water reuse governed in daily operations.[S18][S24] The recommended record for GFT's batch ledger and related tools gives every cubic metre of recycled water a batch-linked quality tag for conductivity, hardness, pH and colour at the reuse header. Daily kilowatt hours, chemicals, backwash volumes, concentrate outflow and dewatered-sludge mass are then reconciled against accepted kilograms of fabric or garments.[S24][S1001] When water quality is matched to the next duty and every residual stream stays inside the boundary, circulation becomes a verifiable engineering reduction rather than a displaced cost.
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.
24 sources · 242 citation marks on this pageMost cited: S1001, 45 times
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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.
c10-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 ↗c10-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 ↗c10-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 ↗c10-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 ↗c10-S06 · Grade B
Textile Wastewater Treatment for Water Reuse: A Case Study
The reuse rate of recycled water in the whole system was 86.8%, higher than that during forward osmosis (FO)-RO system by 31.8% [49].
2019-01-11. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-S10 · Grade B
The Water Footprint Assessment Manual: Setting the Global Standard
The water footprint of a product is the volume of freshwater used to produce the product, measured over the full supply chain.
2011. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-S13 · Grade A
Progress on the proportion of domestic and industrial wastewater flows safely treated: Mid-term status of SDG Indicator 6.3.1 and acceleration needs
We are still unable to make a global estimate of total and industrial wastewater flows due to the under-reporting.
2024. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-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 ↗c10-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 ↗c10-S19 · Grade A
Scope 2 Guidance
The Scope 2 Guidance standardizes how corporations measure emissions from purchased or acquired electricity, steam, heat and cooling (called “scope 2 emissions”).
2015. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-S20 · Grade A
ISO 14040:2006 Environmental management: Life cycle assessment: Principles and framework
ISO 14040:2006 covers life cycle assessment (LCA) studies and life cycle inventory (LCI) studies.
2006. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-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 ↗c10-S25 · Grade A
Cameroon Power Sector Reform Program (P178136): Implementation Status and Results Report
The Cameroon Power Sector Reform Program was approved by the World Bank in August 2023.
2025-06-25. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-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 ↗c10-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 ↗c10-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 ↗c10-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 ↗c10-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 ↗c10-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 ↗c10-S1001 · Grade B
Textile Wastewater Treatment for Water Reuse: A Case Study
The total operating cost of treating textile wastewater is displayed in Table 6, reaching 0.44 USD·m−3 reuse water, wherein the cost of the ozone production was 0.18 USD·m−3 (40%), that of sand filtration, UF and RO system was 0.19 USD·m−3 (43%), and that of machine maintenance, employee cost, agentia, and PAC was 0.08 USD·m−3 (17%).
2019-01-11. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-S1002 · Grade B
Reverse Osmosis Membrane Cleaning Optimization from Textile Dyeing Wastewater Reuse Applications
A significant decline (more than 15%) in RO membrane permeability occurred after RO membrane permeate production of 625 L/m2 at a water recovery ratio of 60%.
2026-01-04. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗c10-S1003 · Grade B
Advances in Physicochemical and Biological Treatment of Textile Wastewater: An Applied Review of Methods, Technologies, and Costs
Although wastewater treatment plants (WWTPs) reduce pollution, they face high costs, sludge generation, and limited removal of persistent contaminants.
2026-07-18. Register access date: 2026-10-30. Source provenance is supplied by the paper evidence register.
Open the recorded source ↗S01 International Finance Corporation, World Bank Group. 2007-04-30.
S06 MDPI, Processes. 2019-01-11.
S02 European Commission Joint Research Centre. 2023.
S37 Emerald Publishing Limited. 2019.
S1001 MDPI, Processes (full-text repository at Living Archive for Process Systems Engineering). 2019-01-11.
R06 Cameroon Trade Hub. Publication date unrecorded; inherited source-text check.
R07 Ecofin Agency. Publication date unrecorded; inherited source-text check.
S03 VTT Technical Research Centre of Finland, Telaketju. 2024-04-16.
S1003 Wiley, Water Environment Research. 2026-07-18.
S38 European Commission. 2022-12-09.
S31 Springer Nature, Scientific Reports. 2022-12-26.
S24 Sustainable Apparel Coalition. 2022.
S18 International Organization for Standardization. 2018.
S1002 Multidisciplinary Digital Publishing Institute (MDPI), Membranes. 2026-01-04.
S36 Elsevier, Dyes and Pigments. 2024.
S04 PLOS Sustainability and Transformation. 2023-07-31.
S10 Earthscan, for Water Footprint Network. 2011.
S20 International Organization for Standardization. 2006.
S25 World Bank. 2025-06-25.
S16 MDPI, Energies. 2022-11-25.
S19 GHG Protocol. 2015.
S33 ZDHC Foundation. 2024.
S13 UN-Habitat and World Health Organization, for UN-Water. 2024.
S32 ZDHC Foundation. 2023.
Keep the thread · chapter 10 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.