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

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

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 www.acvtex.eu AVNIR 2012 2

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 2012 3

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 2012 4

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. 20 18 16 14 12 10 8 6 4 2 0 0 5 10 15 dye (%) Vat Reactive Direct Sulphur dye Indigo (natural vat) Colour strength values of dyed fabric according to the % of dye AVNIR 2012 5

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 2012 6

% LCA of processes - results 100 90 80 70 60 50 40 30 20 10 0 Reactive Direct synthetic vat Indigo Sulphur AVNIR 2012 7

% LCA of processes - results 100 90 80 70 60 50 40 30 20 10 0 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 2012 8

% LCA of processes - results 80 70 60 50 40 30 20 10 0 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 2012 9

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.] 140 120 100 80 60 40 20 0 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 2012 10

Sensitivity analysis Water Scouring Electricity production Thermal energy production Chemical production Water softening Dyeing + rinses Drying Waste water System boundary Finishing AVNIR 2012 11

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 2012 12

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 0,0005 0 CML2001 - Nov. 09, Eutrophication Potential (EP) AVNIR 2012 15

Sensitivity analysis Water AVNIR 2012 16

Sensitivity analysis Water AVNIR 2012 17

Sensitivity analysis Water AVNIR 2012 18

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 2012 19

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 2012 20