Electrolysis: processes – compositions used therein – and methods – Electrolytic material treatment – Water – sewage – or other waste water
Reexamination Certificate
1999-01-26
2001-09-11
Phasge, Arun S. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic material treatment
Water, sewage, or other waste water
C204S242000, C204S248000
Reexamination Certificate
active
06287450
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally concerns water purification systems.
The present invention particularly concerns the purification of water in swimming pools, spas, hot tubs, water storage tanks, wells and water cooling towers by use of galvanic cells in order to inhibit the growth of bacteria, fungus and algae while significantly reducing the amount of chemicals (chlorine, bromine, hypochlorite, persulfate, ozone, etc.) necessary to maintain water quality.
2. Description of the Previous Art
2.1. Water Purification
The paramount function of water treatment is to destroy harmful microorganisms. This is usually accomplished by adding oxidizing agents such as chlorine, iodine and oxygen. In swimming pools and spas, the treatment of water to eliminate microorganism contamination ordinarily incorporates chemical treatment in combination with a mechanical filtering usually accomplished by drawing water from the pool with a pump, forcing it through a filter and returning it to the pool. Because the mere addition of a quantity of a chemical in liquid or soluble form permits the circulation system to effectuate quick dispersal, sanitization treatment is an easy task. Chlorine is typically used as a sanitation agent. However, chlorine is malodorous, rather inefficient, unhealthful, and not particularly economical.
At ordinary temperatures, chlorine is a gas, difficult to handle, and is not generally available. Accordingly, chlorine used in pools and ponds is combined with some compound that dissociates upon addition to pool water. Chlorine is popularly introduced as a constituent of calcium hypochlorite, sodium hypochlorite, chlorinated isocyanurates, or some other acid, or as a salt. If added as a salt, additional chemicals are required to avoid harmful accumulations of any other constituents of the salt, resulting in the problematic requirement of maintaining a chemical balance.
The process of purification of pool water using electrolysis has already been developed, and is well known in the art. Shindell, in U.S. Pat. No. 4,328,084 (1982) describes a water purification system employing salt in quantities sufficient to make the water slightly conductive and circulating that water through the electric field between a pair of dissimilar metal plates in order to dissociate salt ions from the water. The dissociated ions of salt and water are converted to oxidizing agents capable of destroying organic matter, which is converted to substances that can be removed by mechanical filtration. The process reportedly results in economical and effective purification. However, a major problem arises when a purification cell is placed in the circulation piping. The pump must operate continuously to maintain an effective level of chlorine or oligodynamic ions. This is not a problem in large commercial pools, however, in residential pools, the cost of continued operation becomes prohibitive. Also, governmental restrictions apply and costs of installation are high.
Metallic ions are known to kill or control algae and bacteria. It is well established that silver and copper ions are effective bactericides and algaecides. Treatment with silver has been used by NASA to purify water on the Apollo space missions. The practice of using silver and copper vessels to improve water quality dates back to ancient times. Ancient Phoenicians stored wine in silver urns to preserve it, providing one the earliest recorded examples of use of this metal for that purpose. Zinc, aluminum, and gold ions are just a few additional metals that can be used similarly.
Dahlegren, U.S. Pat. No. 4337136, (1982), purifies pool water by using a pair of silver-copper alloy electrodes extending from a floating container. Electrical energy is provided by a battery, using a timer switch that reverses the current as required to reduce erosion of the electrodes. The operating life of such a cell is limited by the requirement of batteries.
Sherman, in U.S. Pat. No. 5,085,753, describes a water purifier with a buoyant housing for supporting a purification cell below the water's surface and for supporting a solar cell array for providing power for the purification cell. The cell operation includes electrolytic processes, electrocution and oxidation to destroy bacteria and algae.
There are two types of undesirable elements in pool water: 1) impurities in suspension, in the form of precipitates or colloids, and 2) dissolved, extremely small, electrically charged impurities in the ionic state. To eliminate these impurities, flocculation processes—consisting of introducing a reactant into the water to create colloids with adsorption properties—have been used. The colloids cause flocculation, which encloses the impurities in suspension. Large particles are formed and are separated from the water by filtering. To facilitate flocculation, the pH of the water has to be adjusted, in many cases, to below 7.4 or above 8.5.
2.2. Water Purification With Metal Ions
Conventional purification devices use either (i) an excess of anodic reaction products, (ii) a particular linear relationship between purification cell current and treated water temperature, (iii) addition of sodium persulfate to water in which copper and silver ions have been added from copper-silver electrodes immersed in the water, or (iv) addition of salt in sufficient quantities to make the water slightly conductive followed by circulating the slightly conductive water through an electric field between a pair of electrode plates. These conventional devices and methods have generally been uneconomical and inefficient, and have focused on producing and regulating a DC current from an AC power source so as to maintain the safety of swimmers. The equipment is expensive, complicated and generally requires special installation and monitoring, thereby increasing manufacturing, operating and liability insurance costs.
Solar powered purification cells can overcome some of these problems, However, other drawbacks such as excessive gassing, corrosion, and accumulation of scale and deposits at the purification cell electrodes, result in reduced efficiency, destruction of the cell and/or the necessity of repetitively cleaning the electrodes.
In U.S. Pat. 5,279,748, issued to Hackett, water is passed through an “electrolytic filter” consisting of packed granules of copper and zinc, or “a copper-zinc filter media.” “As water passes through the electrolytic granules, a chemical reaction causes metal hydroxides to form in controlled amounts. These controlled releases of oxides are carried into the filtered water where they kill bacteria and provide a hostile environment for algae and fungus growth.” The amount of ionized metal entering the pool is controlled by varying the flow rate of water entering the electrolytic filter independent of the physical straining filter. The electrolytic filter is impervious to the bacterial growth to which similar filters (composed of other materials) can be susceptible. Hackett's device is claimed to eliminate the need for chlorine.
U.S. Pat. No. 4,492,618 to Eder discloses a method in which electrodes of a copper-silver alloy are dissolved in the treated water via the application of a periodically reversed direct current. The electrically induced dissolution of the electrodes liberates copper and silver ions into the water. Sodium persulfate is added to the water for the “oxidation of organic matter.”
In U.S. Pat. No. 4,608,247 issued to Heinig, silver is deposited on a large surface area support and combined with carbon to produce a composition favorable to the dissolution of silver ions in water.
In U.S. Pat. No. 5,352,369, also issued to Heinig, a method is described in which silver deposited on a large surface area alumina matrix acts as a catalyst “in the presence of oxygen to form an active oxidizer in the water.” This active oxidizer is claimed to be effective in the containment of bacterial and algal growth.
LeMire, in U.S. Pat. No. 4,935,116, describes a device consisting of concentric cylinders of dissi
Fuess & Davidenas
Phasge Arun S,.
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