A PROCESS OF COMBATTING MICROORGANISMS

Abstract: The invention relates to a process of combatting microorganisms 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.

Description: A process of combatting micro-organisms The invention relates to a process of com¬ batting micro-organisms in industrial processes, par- ticularly 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 circu¬ lating 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 bio- cides to process waters and slurries, such as wide- spectrum bactericides and fungicides, see e.g. Finnish Patents 76 237 and 75 973 and U.S. Patents 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 en¬ zymes, 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 can¬ not 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 SUBSTITUTE SHEET plenty of bacteria and fungi, and the process cir¬ culating waters contain plenty of nutrients. Further¬ more, 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 en¬ zyme binds oxygen and produces long-acting hydrogen- peroxide which kills substantially all micro- organisms. Example 1 Combatting micro-organisms occurring in a starch or starch derivative slurry to be used in sur¬ face sizing Raisamyl 145 starch slurries (100 ml) contain¬ ing conventional micro-organisms were introduced into 250 ml shaking bottles, and 0-500 U/1 glucose oxidase and 0-2 g glucose were added. The mixtures were shaken for several days at 37°C. The compositions of the sample mixtures and the results obtained are shown in Table I. Example 2 Combatting micro-organisms occurring in a starch or starch derivative slurry to be used in sur- face sizing SUBSTITUTE SHEET AVEBE PERF P MRR-176 Starch slurries (100 ml) containing conventional micro-organisms were intro¬ duced into 250 ml shaking bottles, and 50 U/1 glucose oxidase, 0-0.9 g glucose and 0.5 g/1 trypton yeast extract as a source of nitrogen for the micro¬ organisms were added. The sample mixtures were shaken for several days at 37°C. The compositions of the sample mixtures and the results obtained are shown in Table II. Example 3 Combatting micro-organisms occurring in cir¬ culating waters of pulping process Circulating water samples ( 100 ml) containing bacteria of the Bacillus species were introduced into 250 ml shaking bottles, and 0-300 U/1 glucose oxidase and 1.5-3 g glucose were added. The sample mixtures were shaken for several hours at 25 to 50°C. The com¬ positions of the sample mixtures and the results obtained are shown in Tables III and IV. Example 4 Combatting micro-organisms occurring in a kaolin slurry Kaolin slurries (SPS) (100 ml) containing con¬ ventional micro-organisms were introduced into 250 ml shaking bottles and 0-1,000 U/1 glucose oxidase, 0-2 g glucose, and 2.0 g/1 trypton yeast extract as a source of nitrogen for the micro-organism were added. The sample mixtures were shaken for several days at 37°C. Control tests were carried out in which hydro- gen peroxide or a microbicide was used in place of glucose oxidase. The compositions of the sample mix¬ tures and the results obtained are shown in Table V. Example 5 Combatting micro-organisms occurring in a kaolin slurry S U BSTITUTESHEET Kaolin slurries (SPS) (100 ml) containing con¬ ventional micro-organisms were introduced into 250 ml shaking bottles, and 0-500 U/1 glucose oxidase and 0- 2.0 g glucose were added. The sample mixtures were shaken for several days at 37°C. Control tests were carried out in which hydrogen peroxide or a chemical microbicide was used in place of glucose oxidase. The compositions of the sample mixtures and the results obtained are shown in Table VI. Example 6 Combatting micro-organisms occurring in ground- wood Groundwood slurries (100 ml) containing conven¬ tional micro-organisms were introduced into 250 ml shaking bottles and 0-300 U/1 glucose oxidase and 0- 1.6 g glucose were added. The sample mixtures were shaken for several days at 37°C. The compositions of the sample mixtures and the results obtained are shown in Table VII. T TE SHEET TABLE I Starch slurry* Test No. Additives Microbe count/ml Glucose Glucose 0 1 4 1 CO oxidase c 03 (U/1) (g/1) <n H H C H m 0) I mm H Cationized starch slurry (Raisamyl 145), dry matter conten contains the microbe flora formed during the production and s ** Sugar control Control TABLE II Starch slurry* Test No. Additives Microbe count/ml Glucose Glucose 0 1 3 14 (days) oxidase CO c (U/1) (g/1) CD CO H c Hm CO I m Pulp starch slurry (Avebe); dry matter content about 20%; pH 6.7; contains the microbe flora formed during the production and storage of the slurry; trypton yeast extract added 0.5 g/1 ** Control TABLE III Circulation water* Bacteria count (ng ATP/ml***) 0 1 3 6 (h) CO c CO CO H ■ H C H ■ m CO Circulation water from a pulp production process; pH 7.0; the sample was sterilized I m to destroy the natural microbe flora, followed by inoculation by a pure culture of tn the Bacillus species. ** Sugar control Bacterial growth was followed by measuring ATP concentration with an LKB-Wallac luminescence meter. TABLE IV Circulation water* Test No. Additives Bacteria count (ng ATP/ml***) Glucose Glucose Hydrogen 0 2 6 (h) oxidase peroxide O Circulation water from a pulp production process; pH 7.0; the sample was sterilized I m to destroy natural microbe flora, followed by inoculation by a pure culture of the Bacillus species. ** Sugar control ***** Bacterial growth was followed by measuring the ATP concentration with an LKB-Wallac luminescence meter **** Control test (with hydrogen peroxide) TABLE V Kaolin slurry* Bacteria count/ml Hydrogen Fennosan 0 1 4 (days) peroxide B-100 CO c ( ppm ) ( ppm ) CO 1 2.5xl0 3 2 2.5xl0 3 H 3 2.5xl0 3 C H 4 2.5xl0 3 m 5** 250 2.5xl0 3 O X 6** 1000 2.5xl0 3 m 7*** 250 2.5xl0 3 g**** 1. 5 2.5xl0 3 g***** 2.5xl0 3 * SPS kaolin slurry (ECC), dry matter content about 50%, pH 7.5; contains the microbe flora formed during the production and storage of the slurry; 0.25% dispersing agent and 2.0 g/1 trypton yeast extract added ** Control test (with hydrogen peroxide) *** Control test (Fennosan B-100) **** Sugar control ***** Control Bacterial count /ml ) 0 1 4 7 (days ) CO c CO O H H H 250 1000 CO I 250 m SPS kaolin (ECC), dry matter content about 50%, pH 6.9; 0.25% dispersing agent added; contains the microbe flora formed during the production and 4-day storage (37°C) ** Control test (with hydrogen peroxide) *** Control test (Fennosan B-100) **** Sugar control ***** Control TABLE VII Groundwood slurry* Test No. Additives Bacteria count/ml Glucose Glucose 0 5 (h) 1 (day) 4 (days) oxidase CO (U/1) (g/1) c 00 1 300 0 7.9x10^ 3.2x10-- 6.8x10* 10 8 CO 2 300 1.5 7.9xlθ' 74 74 74 -4 Α 3** 1.6 7.9xl0 > 1.3X10 1 1.7xl0 f 3.7xl0 7 c 4*** 3.4xl0 3 3. 2x iθ 4 10 7 5.0xl0 7 -I m CO Groundwood pulp; sterilized and inoculated with the microbe flora of unsterilized I groundwood. ** Sugar control *** Control

Claims: Claims: 1. A process of combatting micro-organisms dis¬ turbing industrial processes, c h a r a c t e r - i z e d by adding glucose oxidase and optionally glucose or a source of glucose to process waters or slurries. 2. A process according to claim 1, c h a r a c¬ t e r i z e d by adding glucose oxidase to the system in an amount of at least 25 U/litre, prefer¬ ably 50-1000 U/litre. 3. A process according to claims 1 and 2 for combatting micro-organisms occurring in a kaolin slurry, c h a r a c t e r i z e d by adding 50-1,000 U/litre glucose oxidase and 0.3-3 g/litre glucose to the slurry. 4. A process according to claims 1 and 2 for combatting micro-organisms occurring in a groundwood or pulp slurry, c h a r a c t e r i z e d by adding 50-1,000 U/litre glucose oxidase and 0.3-3 g/litre glucose to the slurry. 5. A process according to claims 1 and 2 for combatting micro-organisms occurring in a starch solution, c h a r a c t e r i z e d by adding 25-500 U/litre glucose oxidase and 0-3 g/litre glucose to the slurry. 6. A process according to claims 1 and 2 for combatting micro-organisms occurring in the cir¬ culating waters of the wood processing industry, c h a r a c t e r i z e d by adding 25-500 U/litre glucose oxidase and 0.3-3 g/litre glucose to the circulating waters. 7. A process according to claims 1 to 6, c h a r a c t e r i z e d in that the temperature is between 2 and 60 β C, preferably between 10 and 40°C. 8. A process according to claims 1 to 7, c h a r a c t e r i z e d in that the pH is between 2 and 9, preferably between 5 and 8. SUBSTITUTE SHEET

Inventors: LEHTONEN PAAVO OLAVI, LEHTONEN, PAAVO, OLAVI
Applicants: CULTOR OY, CULTOR LTD.
Application year: 1990
Main classification: D21C9
IPC codes: A01N63, C02F1, C02F5, D21C5, D21H17, D21H21