Electrolysis: processes – compositions used therein – and methods – Electrolytic material treatment – Organic
Reexamination Certificate
2001-08-21
2003-01-21
Phasge, Arun S. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic material treatment
Organic
C205S742000, C205S620000, C204S271000, C204S272000, C204S275100
Reexamination Certificate
active
06508929
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to water purification and, in a particular preferred embodiment, to a synergistic combination of a chlorine generator and metallic ion dispenser which produces unexpected benefits of increased reliability, decreased maintenance costs, and improved water purification.
BACKGROUND ART
Chlorine is the most widely used method of neutralizing disease causing pathogens and bacteria in a body of water. Although there are other means of neutralizing bacteria and pathogens, chlorine is the disinfectant of choice for many reasons. Chlorine kills pathogenic organisms efficiently and effectively by attacking the cell or the cell enzyme system. In either case, the inactivation of the pathogenic organisms is achieved. The chlorine residual HOCL is a longer lasting residual that effectively kills pathogens until dissipated. EPA requirements for potable or public water facilities and state requirements for chlorine levels are as follows: 0.2 mg/L-0.5 mg/L free chlorine residual. However, even though chlorine is relatively inexpensive as compared to other types of sanitizers, the cost of chlorine, for instance to sanitize a pool, becomes an extremely expensive proposition over the lifetime of the pool. Moreover, significant hazards, time, labor, and other costs are associated with storing and handling toxic chlorine and/or other hazardous chemicals such as chlorine tablets, oxidizers, algaecides or algae inhibitors. Another problem with the use of chlorine is the need to stabilize the chlorine such that it remains in the water as UV rays tend to deplete or damage chlorine molecules during the day. Cyanuric acid is therefore frequently utilized as a stabilizer in chlorine tablets and is present in dichlor. Cyanuric acid can build up to undesirable levels and should be monitored by knowledgeable pool operators using special test kits. High content of cyanuric acid in pool water presents a health problem, damages pool plaster, and may lock the free chlorine molecule. High levels of cyanuric acid requires draining the body of water and adding fresh water to reduce concentrations.
Other methods of disinfection include use of chlorine dioxide, which is unstable and may produce undesirable byproducts such as chlorates. Chlorine dioxide residuals do not last as long as chlorine residuals and is more difficult to measure and monitor. Ozone, which is an unstable chemical, breaks down rapidly as does UV (ultra violet light) and leaves no residual disinfectant in the water supply. Ozone and UV are costly because the equipment and electricity required to produce ozone gas and UV is expensive compared to other disinfectants as chlorine. Other chemical oxidizers with limited usefulness as disinfectants include potassium permanganate, which is more expensive than chlorine and produces a pink or brown residue in the water. Iodine, which is expensive, stains and produces an objectionable taste. Bromine chloride and hydrogen peroxide are both relatively more expensive methods of sanitizing the water.
Silver, being the least effective method of sanitizing is expensive and reaches a maximum contaminate level (MCL) of 0.5 mg/L which restricts its usefulness as an effective sanitizer but does serve the purpose, even in small quantities, as an algae growth inhibitor. Nonetheless, some prior art devices rely completely on the use of metallic ions or metallic oxides for water purification. The sole use of metallic ions or metallic oxides cannot neutralize disease causing pathogens without breaking or seriously exceeding E.P.A. primary standards for maximum contamination levels (MCL) of copper (Cu) 1 mg/L or 1.0 ppm and Silver (Ag) 0.5 mg/L or 0.05 ppm. Serious side effects to public health could occur should these perimeters be breached either in public, potable, bathing, or swimming water, as all may be ingested. Another problem with ion generating systems, which are discussed in more detail below, is that these system have electrodes which tend to become rather quickly calcified thereby resulting in breakdowns and requiring significant maintenance time and/or additional costs.
As disclosed in the below-listed patents, it is well known to utilize chlorine or ion producing generators to treat water. However, besides the problems already mentioned above, such devices tend to have significant reliability problems and/or require complex chemical production and containment requirements. Moreover, such systems may tend to require expensive installation costs and utilize significant amounts of electricity.
Some systems may utilize 115 VAC or 240 VAC which is applied to electrodes to produce chlorine. This requires power consumption on the electrodes along with power consumption due to pump operation. When the pump is not on, chlorine is not injected into the water. Thus, the consumer has increased electricity bills to pay for both chlorine and pump operation. Moreover, electrical systems in close proximity with salt water can be dangerous in themselves and may tend to cause accidental electrical shock hazards under some conditions. Such systems are also subject to electrical shorting which causes breakdowns, absence of chlorination during breakdowns, repair expenses, and other problems. A calcium buildup occurs at the cell plates which continually reduces the typically rather small gap between the cell plates and eventually causes shorts. Replacement cells may retail at $500.00 and may require replacement as often as every two years, if not sooner. The significant maintenance/repair/operation costs involved with such systems can be disappointing to pool owners who were led to believe their system would reduce costs by eliminating the need to purchase chlorine. Other chlorine generating systems employ voltage reversing circuitry to attempt to shake calcium buildup on the electrode plates. However, this process often results in only limited success at reducing calcium build-up and the practice of reversing tends to further shorten the lifetime of the cells. Other systems create chlorine in a separate tank apart from the pool or other body of water to be purified and therefore require circulation of a pump to inject chlorine in the water. This process may wear down the pump equipment and may be costly in terms of energy required not only to produce chlorine but also required to operate the pump. Moreover, if the pump is not on, then purification stops. In some chlorinator systems, it is necessary to add significant amounts of salt to the pool (e.g. 600 lbs), but the electrodes still become calcified and cease operating. The large amount of salt added to the pool can affect calcium levels required to maintain plaster pools. Moreover, the additional of significant amounts of salt to water presents an added electrical hazard. Fresh water is not a particularly good electrical conductor, but salt water is an excellent electrical conductor. As well, the chemical containing compartments in such devices may contain very concentrated chemicals that can be dangerous, can leak to produce chlorine gas, and may require special and expensive containment features.
U.S. Pat. No. 5,059,296, issued Oct. 22, 1991, and U.S. Pat. No. 5,085,753, issued Feb. 4, 1992, to M. Sherman, disclose a portable self-contained solar powered water purifier for swimming pools, spas, and other bodies of water is disclosed. The purifier includes a buoyant housing for supporting a solar cell array above the surface of water to be treated and a purification cell below the surface of water to be treated. Suitable electrical connections, between the solar cell array and purification cell, are sealed to prevent the entry of water therebetween which could result in electrical shorts and corrosion. The purification cell includes a sacrificial anode, having a metal alloy essentially composed of copper and silver and a cathode which is preferably constructed of stainless steel so as to not react adversely with the sacrificial anode. Metallic copper and silver ions are released by the sacrificial anode to prevent algae
Nash Kenneth L.
Phasge Arun S,.
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