Page 163 - Advances in Textile Biotechnology

144 Advances in textile biotechnology

leave sufficient wax materials on the surface of the fabric to lessen the later
addition of softeners for consumer attraction.

6.5.6 Comparisons of costs
Very little work has been published regarding cost comparisons of alkaline
versus enzymatic scouring, partly because the full enzymatic process for
continuous processing is not complete. Durden et al. (2001) reported on an
in-plant trial on combed ring spun, open-end spun and mercerized cotton
yarns. The trials were done with the commercial alkaline pectinase then
available, though no details of the processes were given in the article. Sub-

stantial savings were claimed but no figures were given. Novozymes has
reported the following for their pectinase scouring process (Wu, 2008):
• Enzyme use: 10 kg per tonne of yarn.
• Chemicals, energy and water saved: hydrogen peroxide, 40 kg; NaOH,
15 kg; acetic acid, 5 kg; yarn, 25 kg; steam, 2500 kg; electricity, 150 kWh;
3
water, 20 m .
A press release of the results of a plant trial collaboration between
Novozymes and Esquel, the Hong Kong-based textile manufacturer,
reported a preparation regime that included bioscouring with pectinase, a
dyeing that included a cellulase treatment to remove fiber fuzz ends, and

another enzyme treatment to remove excess dye (just-style.com, 2009). It
was calculated that 70 000 l of water and 1000 kg of CO 2 per tonne of
knitted fabric can be saved in production of t-shirts. They also claimed a
20–25% reduction in process time.
Ismal (2009) examined water, materials and energy consumption and
costs in some detail for various preparation treatments based on mill and
production conditions. The results showed that enzymatic processes save
water, energy and time compared with conventional treatments. When acti-
vator agent-assisted hydrogen peroxide bleaching was combined with enzy-
matic scouring, there were no time and electricity savings, but water and
steam consumption and cost was reduced. Though the enzymes had higher
costs than conventional materials, the enzymatic processes gave signifi cant
water and energy savings, and a lower total cost than the alkaline scouring
processes.

6.6 Future trends
Given the initial quantity of research regarding enzymatic scouring and
bio-preparation in the mid to late 1990s, it is somewhat surprising that there
are still significant problems to be solved in creating a totally enzymatic

cotton preparation system. Desizing with enzymes is a long-established

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