Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using direct contact with electrical or electromagnetic...
Patent
1998-01-07
2000-06-20
McKane, Elizabeth
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using direct contact with electrical or electromagnetic...
204554, 204263, 204666, 204672, 210748, C25B 900, C02F 148
Patent
active
060774797
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the destruction or inactivation of microbes by subjecting them to a high potential gradient.
2. Description of the Related Art
As shown by publications in the open technical literature (see Technical Bibliography, below) it has been known for at least fifty years that microbes can be destroyed or deactivated by high potential gradients. In the earliest publications (1949-1965) practical application of this phenomenon for the purpose of disinfecting liquids--and liquid foods in particular--was emphasized. Somewhat later (1970-1985), carefully controlled application of high potential gradients to the manipulation of biological cells was studied and reported. Publications described, inter alia, the use of high potential gradients to render the membranes of biological cells permeable, to organize a number of cells into a group and to accomplish the fusion of two or more cells. Practical devices to accomplish these things were developed and offered for sale as commercial products for use in biological laboratories. The microbiological studies associated with this work provided valuable fundamental information on the effect of high potential gradients on cells. Among other things, it became evident that high potential gradients produce porosity and, in some cases, permanent damage to cell membranes by exerting electromechanical force (electrophoretic force) on the membrane. In other words, the observed effects were due to these forces and not due to electric currents or ohmic heating.
While some microbes--such as spores, in particular,--can be found in gaseous media (in the air, for example) or in solid materials or on the surfaces of solid materials, the vital processes of most microbes require a liquid medium--usually an aqueous medium. Such liquid media are usually weak electrolytes (water being an example) and consequently these media have comparatively high electrical conductivity. Conductivity of 0.05 Siemens (S) per meter is a typical value; but values differing from this by a factor of 10.sup.6 would still be classified as "semi-conducting", or "non-insulating". Consequently, it was recognized from the earliest work (1949-1960) that high potential gradients could be applied successfully to media containing microbes only under certain special conditions. A potential gradient of 10.sup.6 volts/meter is of the order of the lowest gradient which will have a permanent effect on a microbe. Such a gradient, applied as a steady (DC) gradient to a medium having a conductivity of 0.05 S/m, would result in a current density of 5.times.10.sup.4 amp/m.sup.2, with consequent power dissipation of 50,000 Megawatts/m.sup.3 ; and the temperature of the medium would rise at an initial rate of roughly 12,000.degree. C./sec. Of course, these considerations were well-known to all who have worked on this subject. Some of the earliest work applied high-frequency AC voltages (Burton--1949; Doevenspeck--1961) but by 1965, pulsed voltages had become accepted as the preferred means of creating high potential gradients in the various media which were studied. (E.g., Hamilton & Sale--1967; Sale & Hamilton--1967,1968). Pulse lengths in the range 0.1 microsec to several milliseconds were employed. It was established that the effect of potential gradients on cells--as measured by the induced porosity of the membrane or by the lethal effect on the cells--increased rapidly as the magnitude of the gradient increased. Sale and Hamilton (1968) presented a formula for the potential difference across a microbe in an electric field which has been widely used ever since. They assumed a spherical cell of radius a.sub.0 in an electrolytic medium (specific resistance .rho. and dielectric constant .kappa.). The cell membrane is assumed to have a very high resistance--high enough that it can be approximated as a perfectly-insulating membrane--while the interior of the cell is assumed to be conducting; that is, its specific resistance is less than .rho.. A uniform potentia
REFERENCES:
patent: 4457221 (1984-07-01), Geren
patent: 5130032 (1992-07-01), Sartori
patent: 5338421 (1994-08-01), Abe et al.
patent: 5575974 (1996-11-01), Wurzburger et al.
patent: 5690978 (1997-11-01), Yin et al.
1990 IEEE Industry Applications Meeting M12 90; "Inactivation of Viruses Using Pulsed High Electric Field": Akira Mizuno, et al.; pp. 713-715.
Milde Helmut I
Philp Sanborn F
Ion Physics Corporation
McKane Elizabeth
LandOfFree
Apparatus for the disinfection of liquids does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for the disinfection of liquids, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for the disinfection of liquids will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1849624