MANUFACTURE OF TEXTILES # 2

Background:

Poly vinyl alcohol (PVA), polyacrylates (PAA) and starch are used in the textile industry for "sizing" cotton fibers; a process where applied chemicals confer strength to the fiber and protect it during the weaving process. The PVA, PAA and starch are removed from the cloth after weaving by washing it in hot water in a "desizing" operation resulting in an aqueous effluent containing these chemicals. Some of these chemicals particularly water soluble sizes such as PVA and PAA can be recovered and reused in the process resulting in savings on expensive chemicals.

Cleaner Production Principle:

Recovery, reuse and recycle.

Cleaner Production Application:

At the textile mill where the present case study was implemented recovery of  poly vinyl alcohol (PVA) was carried out on a pilot scale. A ultra-filtration process to reduce the amount of PVA and starch in the effluent followed by a closed-loop recycling operation was tested for 16 months in a pilot plant. The ultra-filtration membrane used in this process recovered PVA successfully. Starch is enzymatically solubilized prior to desizing and, therefore, can not be recovered. The film forming characteristics of the PAA during testing were impaired by the formation of a calcium-polyacrylate complex.

Environmental and Economic Benefits:

Economic benefits were calculated in terms of raw material savings based on 4DE 6 meters/year cloth production :

This resulted in a net savings of $ 485,000/year from reduced waste generation (900 tons/year) and raw material purchasing needs.

The capital cost for the ultra-filtration plant is $600,000.

Operating costs for ultra-filtration plant was $61,000.

The payback period is 15 months.

Constraints:

None reported.

Contacts:

Type of Source Material: Journal

Citation : Buckley, C.A. 1982. The Performance of an Ultrafiltration Recycling of Textile Desizing Effluents. Water Science and Technology 14:705-713.

Review Status:

This case study was originally compiled by the UNEP Working Group of Textiles. It underwent a UNEP IE funded technical review in 1994 for quality and completeness. It was edited for the ICPIC diskette in July of 1995.

Subsequently the case study has undergone a technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.