Enzyme prebleaching of pulp - perspectives in Indian paper industry

摘要

With the current trends to employ environmentally benign technologies, Xylanase prebleaching could prove to be one of the options before paper industry in reducing the generation of chloro-organic compounds while improving the final brightness of the bleached pulps. The technology has been successfully adopted commercially in number of paper mills in the developed countries but still it is in the developing stage as far as Indian Paper Industry is concerned. Central Pulp & Paper Research Institute (CPPRI) is an apex organization dedicated to applied research in the areas of pulp & paper in India and South- East Asian region. The Institute has carried out extensive studies in the recent past in the area of enzymatic prebleaching of pulps and evaluated several Xylanase enzymes (indigenously developed as well as commercially available) on wood & non-wood based pulps at the Institute laboratory and at various pulp and paper mills in different parts of the country. The five samples of Xylanase enzymes have been evaluated for their bleach response on hard wood and non wood based pulps, the response of two Xylanase enzymes was found to be most encouraging in terms of reduction in demand of elemental chlorine, which was reduced by 15-17%. The other wide spread benefits were improved effluent characteristics specifically the AOX levels which were reduced by 25 - 30%. Other benefits of the process reported included gain in bleached pulp bright of 2 - 2.5% ISO and improved tear strength by 5 - 10% at similar level of bleach chemical demand. The present paper highlights Indian experience on application of enzyme pre-bleaching process for wood and non wood based paper mills covering some of the important considerations during mill scale trial in respect of mill conditions, (temperature, pH and retention time) and the equipment required for effective dispersion of the enzymes to achieve desired efficiency level to make the technology a success in Indian paper industry.