Liquid purification or separation – With preliminary chemical manufacture
Reexamination Certificate
2000-10-10
2003-05-06
Hoey, Betsey Morrison (Department: 1724)
Liquid purification or separation
With preliminary chemical manufacture
C210S321600, C210S323100, C210S416100, C205S747000, C205S751000
Reexamination Certificate
active
06558537
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The filtration system of the present invention relates to a water treatment system that includes filtration as well as reverse osmosis for removal of total dissolved solids (TDS) from water to render the water potable.
The oxidant generating apparatus and method of the present invention relates to water disinfecting systems, and more particularly, to an apparatus for generating disinfecting solutions to be added to potentially contaminated water to render that water potable.
2. Background Art
Removing impurities from drinking water supplies is a major factor in reducing the health risks to the human population. High levels of total dissolved solids (TDS) in water, such as dissolved salts in seawater, make the water unfit for drinking because of the ion imbalance in the human system. Most drinking water in the world today comes from ground or surface water sources and potable water from these sources is produced at small and large municipal drinking water treatment plants. A very small percentage of drinking water is produced from de-salination facilities. There are many settings in which these large systems are not practical. For example, campers, military personnel, and disaster relief situations require small man-portable systems that can treat water from just about any water source to produce potable water. To be effective in such remote settings, a system must be capable of repeated operation with little operator skill, no external power sources, and very little maintenance.
To be fully comprehensive, water filtration must include the capability for both conventional filtration as well as desalination. Conventional filtration can remove particulates that cause turbidity such as dirt, silt, sand, and larger organisms such as Giardia and Cryptosporidium. Reverse osmosis (RO) technology must also be included to remove ions from such sources as seawater. At sea water concentrations of 35,000 milligrams per liter (mg/L), the system must be effective enough to remove ions to levels less than 1000 mg/L. While sodium and chloride are the two ions of concern in seawater, the system must be able to remove other ions as well. All of these ions are collectively known as TDS.
Existing technology removes TDS utilizing RO technology. The pressure required to drive the RO process utilizes a pressure recovery feature to reduce the applied force. U.S. Pat. No. 3,749,524 to Jordan, entitled Manually Operated Pump Utilizing Backpressure for Easement of Pump Stroke, discloses a pressure recovery feature for a pneumatic application. This system does not apply to fluids such as water, and lacks a simplified valve system for retentate discharge, as well as a valve system for isolating the RO element in the event that TDS removal is not required. U.S. Pat. No. 4,124,488 to Wilson, entitled Water Purification by Reverse Osmosis, and U.S. Pat. No. RE033135 to Wanner, Sr. et al, entitled Pump Apparatus, discloses a reverse osmosis pump mechanism with pressure recovery feature. The present invention addresses the current problems by incorporating a simple valve mechanism integral to the piston and shaft for retentate discharge, as well as incorporating a valve switching mechanism to isolate the RO element for conventional filtration, thereby providing maximum efficiency for either reverse osmosis pumping and/or sweet water pumping by two different modes of operation. U.S. Pat. No. RE032144 to Keefer entitled Reverse Osmosis Method and Apparatus, discloses a pump mechanism with pressure recovery and accumulator for reverse osmosis. The mechanism does not incorporate a simple pressure relief and retentate discharge mechanism integral to the piston and rod assembly, nor does the device incorporate a valve switching mechanism to isolate the RO element for conventional filtration.
While filtration presents one manner by which a substance can be rendered potable, and/or free of contaminants and/or fouling agents, chemical and/or radiative methods and devices are also suitable for destroying contaminants and/or fouling agents. In addition, such chemical and/or radiative methods and devices have more widespread use in, for example, bleaching and/or degrading material.
In general, maintaining the sterility of drinking water supplies is a major factor in reducing the health risks to human populations. While large metropolitan water systems can make use of highly toxic chlorine gas for sterilizing drinking water, such systems are impractical in remote locations, which lack highly trained personnel and the equipment to maintain the systems. There are many settings in which sophisticated systems are not practical. For example, campers or military personnel in the field cannot be expected to operate such a system to provide potable drinking water from streams or other potentially contaminated water sources. To be effective in such rural settings, a system must be capable of running for long periods of time with little or no maintenance. In addition, the raw materials required by the system should be readily available.
Systems based on the electrolytic production of chlorine and/or other chlor-oxygen species based germicidal agents are useful for decontamination. These systems require electricity and common salt as raw materials. One such system is described in U.S. Pat. No. 4,761,208 to Gram, et al. entitled Electrolytic Method and Cell for Sterilizing Water, which is incorporated herein by reference. The oxidant generating system of the present invention uses, in a preferred embodiment, an electrolytic cell to generate an oxidant solution including, for example, chlorine in the form of hypochlorous acid and other chlor-oxygen species. Other embodiments of the present invention produce an oxidant solution that is predominantly sodium hypochlorite. The oxidant solution is preferably produced from a brine solution using common salt. This oxidant solution may be added directly to the drinking water at a dilution ratio compatible with the concentration of the oxidant produced in the device and the demand of the water. In general, the oxidant produced by apparatus and/or methods of the present invention is more effective at inactivation of microorganisms than is conventional chlorination technology, including chlorine gas, sodium hypochlorite, and calcium hypochlorite. At adequate dilution ratios, the water is sterilized without causing the water to become unpalatable. This technology is particularly attractive because of its simplicity and long maintenance free operation time. Studies have been conducted to demonstrate the microorganism inactivation effectiveness of the oxidant, commonly referred to as mixed-oxidant solution. Linda V. Venczel, Michael Arrowood, Margaret Hurd, and Mark D. Sobsey with the University of North Carolina at Chapel Hill, North Carolina have conducted research and published a paper entitled, Inactivation of
Cryptosporidium parvum
Oocysts and
Clostridium perfringens
Spores by a Mixed-Oxidant Disinfectant and by Free Chlorine, published in
Applied and Environmental Microbiology,
April 1997, p. 1598-1601.
The systems based on mixed-oxidant production have been used successfully in rural communities with small water supplies to larger municipal water systems treating millions of gallons per day. These larger systems are not well suited for use by individual campers and personnel in the field who must treat small quantities of water on a daily basis. The mixed oxidant systems designed to date are applicable to large quantities of water and are large and heavy. In addition, these systems require quantities of electrical power that are not practical at the mesoscale, or individual person level.
SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
A preferred embodiment of the present invention is an apparatus for treating and disinfecting a substance, the apparatus comprising at least one filter, and a portable electrolytic cell for generating oxidation/reduction products, the products to be subsequently added to the sub
Bradford Wesley L.
Clement Allen D.
Cushman Timothy A.
Herrington Rodney E.
Hickerson John K.
Fain Katy C.
Hoey Betsey Morrison
Miox Corporation
Peacock Deborah A.
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