

Author: Lee Young H. Pavlostathis Spyros G.
Publisher: Water Environment Federation
ISSN: 1938-6478
Source: Proceedings of the Water Environment Federation, Vol.2001, Iss.13, 2001-01, pp. : 136-157
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Abstract
The objective of the work presented here was to evaluate the feasibility of biological decolorization and reuse of textile reactive azo dyebaths. Decolorization of three spent dyebaths was investigated using a suspended-growth, halotolerant, mixed culture under anoxic conditions and a high extent of color removal was achieved ranging from 77 to 90 %. The three azo dyebaths and their decolorization products did not inhibit the halotolerant culture in terms of glucose utilization and acetic acid production. Repetitive dyeing with the same biologically decolorized dyebath for up to five cycles using a biofilm reactor and dyebath pH adjustment during the redyeing process resulted in almost identical fabric color shades as those of standard dyeing using fresh water. Color removal efficiencies using the biofilm reactor were in the range of 86 to 95 % during the repetitive five decolorization cycles without any inhibition and residual color build-up. Excellent fabric color reproducibility was also obtained by using biologically decolorized dyebaths in cross dyeings with different dyeing recipes. To our knowledge, this is the first report on the feasibility of biological decolorization of spent reactive dyebaths using a halotolerant, mixed culture and the direct reuse of the renovated dyebath as process water in the dyeing process. In-plant application of a closed-loop dyeing and decolorization is feasible, which has the potential to not only decrease wastewater volume and treatment cost, but also minimize water use and the discharge of textile pollutants such as salt and dyes.
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