Chemical Substitution
- Use of ammonium sulphate in place of acetic acid for pH adjustment
in disperse dyeing. Although the salt concentration of the effluent would increase in this substitution, ammonium would serve as a nutrient in the biological treatment process [10]
;
- Substitute formic acid for acetic acid in dye baths. Acetic acid has a BOD of 0.64 Kg BOD/Kg and Formic acid 0.12 Kg BOD/Kg [10]
;
- Use single-class dyestuffs like Indigosol, pigments, etc. for dyeing blended varieties in pale shades in place of two stage dyeing using two different classes of dyes [10]
;
- Combined Disperse and Reactive/Direct colour-dyeing of blended fabrics containing low percentage of cellulosics [10]
;
- Use all-aqueous phthalogen blue dyeing in place of solvent-based phtahalogen blue dyeing which requires speciality products [6]
;
- Use of monochlorobenzene in the place of other carriers for dyeing Dacron
[10]
;
- New classes of fibre reactive dyes, e.g. triazine based will reduce the use of azo dyes and contribute to the discharge of lower concentrations of dyes during washing and rinsing [6]
;
- Replace all chromates used for oxidation of vat dyes
[6]
;
- Use sodium bicarbonate (in place of acetic acid) in conjunction with peroxide or perborate in the oxidation of vat dyestuffs [10]
;
- High-temperature reactive dyes [2]. For simultaneous application of disperse and reactive dyes. Energy reduction, elimination
of caustic bath required after disperse dyeing [2]
.
References from reviewed literature:
In [2] J.S. Badin and H.E. Lowitt, The U.S. Textile Industry:
An Energy Perspective, DOE/RL/01830/T-56, prepared by Energetics, Inc. for Pacific Northwest Laboratory, Richland, Washington, 1988.
Copper-free dyes for producing green shades in 100% cotton fabric
[2] [35]. Reduced toxicity (metal content) of spent dye bath and washwater.
References from reviewed literature:
In [2] F.C.Cook, "Environmentally Friendly: More than a Slogan
for Dyes", Textile World, November 1990, pp 49-54.
Shift to fiber-reactive dyes can often provide pollution prevention
opportunity since, according to reference [1], these dyes tend
to have higher exhaustion rates, leaving less unused dye in the spent-dye solution discharge.