Substitution of Synthetic Warp Sizes for Starch and Gelatin

[2] [6] [10] [30] [32] The substitution of synthetic warp sizes (1-3% BOD) for starch (50% BOD) and gelatin (100% BOD) can give a substantial reduction in the organic load of the effluent from desizing.

Use synthetic warp sizes (based on PVA and acrylates) in place of the conventional starch-based preparation [10]. CMC, PVA etc. are mostly recoverable. Starch size can contribute up to 50% of the total BOD loading from processing of woven fabrics so there is frequently a powerful economic incentive to switch from starch to the recoverable sizes such as PVA or CMC to reduce BOD [30]. The recoverable sizes are, however, more expensive than starch.

Ultra-filtration technology is one of the promising methods employed to recover the size [10]. According to reference [32], both capital and operating costs for ultra-filtration are highly dependent on the concentration, flow rate, type of membrane used, nature of sizes, rate of membrane flux and membrane fouling; all alter the economics of the system. As an example, the authors quoted a payback period of 1.5 years for PVA recovery with a feed rate of 5.7 m3/hr at 1% PVA, when the values of the PVA and energy (hot water recycle) recovered and the costs for power, labor and membrane replacement were considered.

References from reviewed literature:

In [2]: Brent Smith, A Workbook for Pollution Prevention by Source Reduction in Textile Wet Processing, available from the Pollution Prevention Pays Program, North Carolina Department of Environment, Health, and Natural Resources, Raleigh, N.C., 1988

F.C.Cook, Fabric Processes Beholden to Energy, Environment, Textile World, November 1990, pp.49-54

J.D. Nirmal, V.P.Pandya, N.V.Desai, R.Rangarajan, Cellulose Triacetate Membrane for Applications in Plating, Fertilizer and Textile Dye Industry Wastes, Separation Science and Technology, 27(15): 2083-2098, (1992)