Levanases for control of slime in paper manufacture

Formation of slime deposits is a major problem facing paper industries. The slime may be biological or nonbiological. Biological deposits that are composed of varied microflora along with fibers, fillers and dirt are the most troublesome. Slime producing microbes secrete extracellular polysaccharides that gum up the process machinery. The specific nature of slime and its formation depend on the mill environment. Correspondingly, countermeasures vary with the type of slime deposit. Conventional slime control methods generally employ combinations of biocides. This leads to effluent toxicity, as well as high processing and treatment costs. Therefore, alternative control measures are in demand. Once such measure is the use of enzymes (levanases) that dissolve the slime to some degree and improve biocide penetration into the slime layer. As a result, the amount of biocide required is reduced, process economics improve and effluent treatment is simplified. (C) 1998 Elsevier Science Inc.