Liquid purification or separation – Processes – Chemical treatment
Patent
1998-09-02
2000-04-04
Simmons, David A.
Liquid purification or separation
Processes
Chemical treatment
210764, C02F 172
Patent
active
060457082
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
All living microorganisms have developed various protective mechanisms against lethal factors. In group microorganisms this developed resistance is especially significant. Microorganisms can form spores which are more resistent to dryness, heat, chemicals and ultrasonics in comparison with the vegetative maternal cells. The spores can under favourable circumstances grow to become a vegetative cell again.
DESCRIPTION OF THE RELATED ART
Sterilization is a treatment to relieve the object of all living organisms and viruses. A reliable method for a chemical sterilization would also be desirable in several connections. At present there only a few possible substances. The substances must be easily removable from the object after the sterilization and not leave any toxic by-products, and simultaneously have a strong sterilizing effect. Halogen preparations such as chlorine gas, chlorinated lime (for the disinfection of cow houses and chemical toilets) and iodine solutions, organic solvents, heavy metals such as copper sulfate (as a fungicide against fungi and also against algae) and detergents might be mentioned as examples of chemical sterilizing agents.
Spores are a large problem in various fields and there is today no efficient method to kill spores. Certain spores are extremely resistant to dryness, radiation, chemicals and ultrasonics and may survive a cooking (at 100.degree. C.) for several hours. For killing spores an autoclaving procedure is required at 121.degree. C. or a fractionated sterilization; this, however, does not provide complete safety. For a sterilization with dry heat a temperature of 160.degree. C. is required for two hours to kill the spores (Mikrobiologi, Mikrobiologiska institutet, Lund, 1982). These methods of sterilization, however, cannot always be practically performed. Various chemical means are also used to kill spores. Formaldehyde in a water/alcohol-solution is used to a large extent to "sterilize" surgical instruments. Even if the solution is said to have a spore killing effect when used for this purpose, its spore killing effect seems to be somewhat questionable (Kirk Othmer, second edition, volume 2, page 640 <1967>). Saturated dialdehydes and especially glutaraldehyde CHO(CH.sub.2).sub.3 CHO have recently been found to have a sterilizing effect, including even a spore killing effect, when used in a water/alcohol-solution in the presence of an alcalizing agent, such as sodium bicarbonate. The bacteria killing effect for vegetative pathogens is said to happen within ten minutes, but an incubation is required during three hours to kill any resistant bacteria spores (Kirk Othmer, second edition, volume 2, page 641 <1967>). Friedl et al have exposed spores from five anaerobic (Clostridium botulinum, lentoputrescens, perfringens, sporogenes and tetuni) and five aerobic (Bacillus anthracis, coagulans, globigii, stearothermophilus and subtilis) microorganisms to ethylene oxide which has an intensive microbicidal effect. When exposed at room temperature the dry spores of Bacillus subtilis and Clostridium sporgens survived during several hours, whereas the other tested organisms were killed after a short period of time. None survived an exposure of eighteen hours (Kirk Othmer, second edition, volume 2, page 641 <1967>). These examples demonstrate the enormous resistance of spores against various chemical control means.
Further examples of difficultly controlled microorganisms are slime bacteria and algae. In the paper pulp industry, for example, these organisms cause severe problems. Microorganisms can be partly controlled by means of chlorine. As the paper pulp industry is forced not to use chlorine any longer and to use hydrogen peroxide instead, the problems with algae and slime bacteria have increased. There exists nowadays no efficient agent against these organisms which is adapted to the environment.
In the brewery industry a great problem is presented by yeast fungi. Yeast fungi are said to present 90 percent of the destruction o
REFERENCES:
patent: 4476108 (1984-10-01), Kessler et al.
patent: 4753681 (1988-06-01), Giuffrida et al.
patent: 4863445 (1989-09-01), Mayhan et al.
patent: 4926795 (1990-05-01), Hamilton et al.
patent: 4975109 (1990-12-01), Friedman, Jr. et al.
patent: 5256182 (1993-10-01), Friedman, Jr. et al.
P.C. Quimby, Jr., et al., "Sodium Carbonate Peroxyhydrate as a new Algicide", STN International File CROPU No. 86-91013, Weed Sci. Soc. Am., 1984.
P.C. Quimby et al., "Sodium-Carbonate Peroxyhydrate as a Potential Algicide", STN International File SCISEARCH No. 88:595776, Journal of Aquatic Plant Management, vol. 26, No. Jul. 1988, pp. 67-68.
"Sodium percarbonate (PCS) will increase detergents' effectivness in bleaching and stain removal for textiles and tableware, cooking untensils and food containers, and is an algicidal and antibacterial cleaner for hard surfaces such as floors and walls", STN International File PROMT No. 80:45138, Household & Personal Products Industry, Jul. 1980, pp. 77-78.
K. Katayama, "Exfoliation and breakage of slime-using sodium peroxide opt with a strong alkali", File WPI N. 72-69505T.
Koei Chem Co Ltd, "Descoting agent comprising organic and inorganic substances-contains sodium percarbonate as main component and chelating agent and surfactant as minor components", File WPI N. 76-95334X.
S.S. Block, "Disinfection, Sterilization, and Preservation", pp. 654, 677-684, Chemical Disinfection of Medical and Surgical Materials, 2nd Edition, 1977.
Morrison Betsey J.
Simmons David A.
LandOfFree
Method for controlling microorganisms does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for controlling microorganisms, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for controlling microorganisms will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-361685