Process for combating microorganisms

The invention relates to a process of combatting micro-organisms in industrial processes, particularly in the wood processing industry, by adding glucose oxidase and optionally glucose or a source of glucose to the process solution or slurry.

The invention relates to a process of combatting micro-organisms in
 industrial processes, particularly in the processes of the wood processing
 industry. The invention is particularly suitable for the treatment of
 process waters and slurries in the wood processing industry, such as pulp
 and circulating waters, pigment slurries (kaolin, gypsum and talc
 slurries, etc.) and pulp and surface sizing slurries (starch slurries,
 etc.).
 Industrial process waters and slurries often contain micro-organisms which
 may hamper the process and impair the quality of the product. For this
 reason, it is usually necessary to add chemical biocides to process waters
 and slurries, such as widespectrum bactericides and fungicides, see e.g.
 Finnish Patents 76 237 and 75 973 and U.S. Pat. Nos. 3,929,561 and
 4,295,932. These biocides are highly poisonous (second-class poisons) and
 may degrade very slowly in the environment.
 It has also been suggested to use enzymes which degrade micro-organisms,
 see e.g. Finnish Patent 75 973. Enzymes are not poisonous and do not
 pollute the environment; in addition, they are needed in very small
 quantities only (a few ppm). The suggested enzymes, however, are
 hydrolytic enzymes which are specific for certain polysaccharides only, in
 addition to which bacteria present in process waters usually adapt very
 rapidly to these enzymes. In other words, these enzymes have a low
 efficiency, and cannot be used in industrial processes.
 In the paper industry in particular, it is absolutely necessary to combat
 micro-organisms. Pigment slurries and starch solutions often contain
 plenty of bacteria and fungi, and the process circulating waters contain
 plenty of nutrients. Furthermore, the temperature and pH are usually
 favourable, especially for the growth of fungi. Because of their
 thread-like growth, fungi may cause serious process disturbances, such as
 blocking of filters, occurrence of pinholes in paper, and colour defects.
 Bacteria may cause formation of bad-smelling and even dangerous gases and
 corrosion of pipe systems and equipment. Only very low bacteria counts are
 acceptable in food-grade paper products, and the products must not contain
 any pathogenic bacteria.
 By means of the process of the invention, it is possible to combat
 micro-organisms effectively and economically in industrial processes. The
 process of the invention uses glucose oxidase which is an
 oxidation-reduction enzyme (oxidoreductase). The enzyme binds oxygen and
 produces long-acting hydrogenperoxide which kills substantially all
 micro-organisms.