Dyeing to receive clear waste

The Applied Technology Unit (ATU) at Queen's University Belfast's award-winning Questor Centre has developed a novel process for removing colour from dye-house effluents. The patented process, known as Biocol, was developed in co-operation with the British Textile Technology Group and has been designed to de-colour a range of spent dyes including reactives, widely regarded as the most problematic dye type to remove from dye-house wastewaters. The process is compact, does not produce waste sludges and can be used to treat even the most concentrated of spent dyes.

The University of Leeds originally isolated the organism used in the system. Questor's ATU then developed the fundamentals of the Biocol process as part of a four-year research programme funded by the International Fund for Ireland. In June 2000 further funding was obtained from the Department of Trade and Industry's (DTI) Biowise programme. The funding allowed Questor to build a small-scale version of the system and install it at the Kells, Northern Ireland, site of John Hanna, a company which bleaches, dyes and finishes materials for the clothing market. The small-scale system has been operating successfully since April 2001, typically removing upwards of 95% of the visible colour from the wastewaters produced. John Hanna has evaluated Biocol alongside a range of the more conventional end-of-pipe treatments and concluded that the new system was the only economically feasible process for removing colour from its wastewaters.

Biocol was initially designed to efficiently treat the highly-concentrated spent dye bath water associated with pad and package dyeing, without the dilution associated with end-of-pipe treatments. This feature means much smaller volumes of wastewater can be treated than with the more conventional 'end of pipe' systems. At John Hanna for example, Biocol will treat only the spent dye baths and coloured rinse waters, 20% of the overall wastewater produced at the site. The resulting plant is much smaller and therefore intended to be more cost effective to install and run than conventional technologies. The full-scale system which will be installed at John Hanna will occupy 6m² of floor space.

Biocol is a modular system consisting of a main unit that houses the pumps and controls and a cartridge module. The cartridge module occupies approximately 1.5m² of floor space and has a life span of around nine months. At the end of this period spent cartridges are replaced with fresh ones and the old cartridges are returned for regeneration. Because of the modular nature of the process, adding an additional cartridge module can easily double capacity.

Questor Technologies, a company originally spun-out from the Questor Centre will install the first full-scale Biocol unit at the John Hanna site early in 2002.