Comparison of methodologies for LCA processes - Application to the dyeing of cotton

Transcription

1 Comparison of methodologies for LCA processes - Application to the dyeing of cotton Vanessa Pasquet Sandrine Pesnel Anne Perwuelz Nemeshwaree Behary GEMTEX: university research laboratory in the field of textile materials and processes

2 ACVTEX project Interreg IV project between Southern Belgium and Nord Pas-de-Calais region (end in 2012) 4 members : Main lines : Realisation of Life Cycle Assessment (LCA) Implement the Best Available Technologies (BAT) Help for the REACH legislation Recycling of co-products AVNIR

3 Problem of cotton dyeing industry Cotton dyeing involves high water consumption, energy use and also input of a wide range of chemicals. Water Chemicals (Dyes, surfactants, etc..) Electricity Thermal energie Dyeing process Emissions in Water, air and soil Waste Dyed textile AVNIR

4 Cotton dyes Cotton fiber can be dyed with 4 different dyes: Reactive, Direct, Vat, Sulfur Each class of dye involves different process in terms of bath temperature, time of and chemicals used. Objectives: Compare different cotton dyeing processes with LCA processes Focus on the modeling of water emissions and water s AVNIR

5 K/S max Laboratory tests Methodology to determine the fonctional unit: We performed tests in lab to ensure the similar properties in terms of colour strength (given by K/S values) and dyeing durabilities of 5 dyes processes dye (%) Vat Reactive Direct Sulphur dye Indigo (natural vat) Colour strength values of dyed fabric according to the % of dye AVNIR

6 LCA of processes - Methodology Functional unit: to dye 1 kg cotton fabric with a colour strength given by a K/S max value of 8 and good rubbing and washing durabilities Scouring Electricity production Thermal energy production Chemical production Water softening Dyeing + rinses Drying Waste water System boundary Finishing Software : GaBi (PE International AG) Data sources: lab tests, theoretical values for energies consumption, databases of Gabi and ELCD for generic data and publications for the production of indigo Calculation of the impacts: ReCiPe method (mid point) AVNIR

7 % LCA of processes - results Reactive Direct synthetic vat Indigo Sulphur AVNIR

8 % LCA of processes - results Reactive Direct synthetic vat Indigo Sulphur Dyeing with natural indigo dye -> highest environmental impact Due to the high impact of the agro-sourced dye production. AVNIR

9 % LCA of processes - results Reactive Direct synthetic vat Sulphur Dyeing processes with the synthetic reactive and direct dyes are more beneficial than vat or sulfur dyes Due to the lower dyeing temperature, shorter dyeing time, less auxiliary products and less number of rinses required. AVNIR

10 Sensitivity analysis - colour The results can not be extrapolated to another colour intensity. Dyeing processes associated with dark, pale and normal shades, for the reactive dye only were compared. -> Bleaching step with clear tones before dyeing MD [kg Fe eq] WD [m3] ME [kg N-Equiv.] CC [kg CO2-Equiv.] FD [kg oil eq] FE [kg P eq] HT [kg 1,4-DB eq] Pale shades is 19 % less than that of normal or dark shades. The additional bleaching step leads to an increase in impact categories Caused mainly by the production of the oxidizing agent used. IR [kg U235 eq] Clear tone Bleaching + clear tone Midtone Dark tone AVNIR

11 Sensitivity analysis Water Scouring Electricity production Thermal energy production Chemical production Water softening Dyeing + rinses Drying Waste water System boundary Finishing AVNIR

12 Sensitivity analysis Water Scenarios Emissions into water Modelization of the wastewater No emission No emission No wastewater COD output COD (measured) output No wastewater Molecules output Municipal station Textile station List of molecules into effluent in output No emission No emission No wastewater Presence of a municipal wastewater Presence of textile specific wastewater Textile station + COD rate No emission Presence of textile specific wastewater with COD abatement rate AVNIR

13 Sensitivity analysis Water Scenarios Emissions into water Modelization of the wastewater No emission No emission No wastewater COD output COD (measured) output No wastewater Molecules output Municipal station Textile station List of molecules into effluent in output No emission No emission No wastewater Presence of a municipal wastewater Presence of textile specific wastewater Textile station + COD rate No emission Presence of textile specific wastewater with COD abatement rate AVNIR

14 Sensitivity analysis Water Scenarios Emissions into water Modelization of the wastewater No emission No emission No wastewater COD output COD (measured) output No wastewater Molecules output Municipal station Textile station List of molecules into effluent in output No emission No emission No wastewater Presence of a municipal wastewater Presence of textile specific wastewater Textile station + COD rate No emission Presence of textile specific wastewater with COD abatement rate AVNIR

15 Sensitivity analysis Water [kg N - eq] [kg N - eq] [kg Phosphate-Equiv.] [kg P eq] 0,005 0,004 0,003 0,002 0,001 0 ReCiPe Midpoint (H) - Marine eutrophication ReCiPe Midpoint (H) - Freshwater eutrophication 3,00E-06 2,50E-06 2,00E-06 1,50E-06 1,00E-06 5,00E-07 0,00E+00 0,009 0,008 0,007 0,006 0,005 0,004 0,003 0,002 0,001 0 TRACI, Eutrophication 0,004 0,0035 0,003 0,0025 0,002 0,0015 0,001 0, CML Nov. 09, Eutrophication Potential (EP) AVNIR

16 Sensitivity analysis Water AVNIR

17 Sensitivity analysis Water AVNIR

18 Sensitivity analysis Water AVNIR

19 Discussion of the method Quality aspects of dyeing processes have to be taken into account in the functional unit. Modeling of effluents and wastewater has a considerable influence on the impacts. Some dyes are toxic for humans, their cytotoxicity should be evaluated and include in the comparison. Lifetime of a dyeing according to durability tests should be taken into account in a LCA of product. AVNIR

20 Conclusions Natural dye production step is polluting > Necessity for Eco-design culture and extraction of these dyes Reactive and direct dyes are quite interesting from an environmental point of view comparing to vat and sulphur dyes. Study different machines with different liquor ratios, energy consumption could also be realized to compare cotton dyeing processes. AVNIR