Electrolysis: processes – compositions used therein – and methods – Electrolytic material treatment – Organic
Reexamination Certificate
2002-02-12
2004-08-24
Phasge, Arun S. (Department: 1753)
Electrolysis: processes, compositions used therein, and methods
Electrolytic material treatment
Organic
C205S742000, C205S466000, C204S228300, C204S228600, C204S229600, C204S275100
Reexamination Certificate
active
06780306
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an electroionic water disinfection apparatus for the inactivation and destruction of pathogenic and other microorganisms present in potable water and wastewater including community water supplies and other large industrial/commercial water and wastewater systems.
Water, both in drinking and wastewater applications, contains microorganisms. Various water treatment systems are provided for disinfecting water to a level suitable for human and animal consumption. Other systems treat wastewater with a reduction in the infectious components to levels which are not suitable for human or animal consumption, but are satisfactory for discharge into various water bodies. Similar water disinfection systems may be applied in both applications to reduce the microbial contaminant level to certain specified governmental standards. Historically, the use of chlorination for disinfection has been pervasive, and in recent years systems employing ozonation and ultraviolet radiation have been commercialized.
Various prior art electroporation systems have been suggested for the inactivation of bacteria from water including wastewater. The technique is generally based on increasing cell membrane permeability using very high voltage electric fields. The water is passed through a disinfection unit having spaced electrodes which are connected to a high voltage source, generally on the order of kilovolts. The high electric field changes the permeability of microbial cells and creates a transient, reversible and/or a permanent and irreversible state of increased porosity. The transient condition usually arises at lower values of electric field intensities. The permanent and irreversible state thus is generally operable at much higher levels. Although such systems have been developed, the required high voltage power supply is very costly and also may raise serious safety problems. Electroporation disinfection systems also consume large amounts of electric power. Electroporation systems have disadvantages not only from the cost, but also from the practicality of the system as applied to large water utility and wastewater applications. Further, requirements for large flow cells within closed systems or open channels limit the current state of the art in electroporation systems.
In summary, such electroporation systems have found use only in limited, point-of-use applications where small pipe diameters are the rule. However, commercially applicable systems for water treatment plants and large-scale wastewater processing have not found significant application.
Alternate systems based on ionic current flow within water have been suggested, particularly for limited flow systems such as swimming pools and other like bodies. These systems, however, use metals such as zinc, copper, lead, silver or the like which introduce toxic ions into the water. This approach raises further questions of acceptability and compliance with federal and state chemical contamination limits.
For example, U.S. Pat. No. 3,936,364 which issued Feb. 3, 1976, and U.S. Pat. No. 4,734,176 which issued Mar. 29, 1988 and U.S. Pat. No. 4,936,979, which issued Jun. 26, 1990, disclose ionic water treatment systems, particularly for disinfecting water in swimming pools and the like. Both U.S. Pat. Nos. 3,936,364 and 4,734,176 disclose the use of metal electrodes including or selected from a silver, tin, lead or copper for establishing an ionic condition for treatment of the water passing between the electrodes. U.S. Pat. No. 3,936,364 which teaches the use of silver electrodes, in the form of spaced electrode silver rods, recognizes the danger of toxicity therein and proposes the necessity of a pair of sequential operating electrode cells, with the first unit including silver electrodes and the second unit especially constructed with steel coated or zinc plated electrodes. The first module had electrodes of silver to remove bacteria, but which introduces toxic silver ions into the water. The second module has silver electrodes coated with steel or zinc which is used to eliminate the effect of the silver ions introduced into the water by the first module. In all of the illustrated embodiments, the first module has silver electrodes and the clarifying module includes zinc coated silver electrodes. The patent discloses various test examples but does not set forth the flow rate or give information as to indicate a practical application of the system. Further, it is questionable whether the use of silver electrodes and/or zinc coated silver electrodes would provide an acceptable system to permit a high flow rate in large pipes or open channels or provide a cost effective and reliable system. The use of silver electrodes would hardly be cost effective even if the system could operate in the large channels and the necessary flow rates of large water systems of municipal size or other commercial installations. U.S. Pat. No. 4,936,979 discloses a system, particularly shown for use in swimming pools, including electrodes formed of copper, lead and zinc. Copper is specially noted as used to ensure removal of algae and is noted as an optional use where algae is not a problem. Lead and zinc are taught as electrodes necessary for disinfection of the water. Lead would be considered a particularly difficult model to use even for disinfection because of the adverse effect of lead in products for human consumption or environments, and the extremely low maximum contaminant levels (MCL) established by the EPA and other governmental agencies.
The treatment of wastewater does not provide water suitable for human consumption, either by drinking, use in cooking, washing of product for consumption and the like. Rather, wastewater is defined by various public and governmental standards so as to permit discharge, when properly treated and disinfected, into relatively large bodies of water, such as lakes and rivers. Generally, wastewater treatment presently requires processing to meet the following basic content specifications: Total suspended solids less than 30 milligrams per liter (mg/L); Biological oxygen demand (BOD 5) less than 30 mg/L; Fecal coliforms bacteria less than 200 colonies per 100 ml. Certain specifications may also require nutrient removal including (1) Nitrogen, (2) Ammonia and (3) Phosphorous.
Various wastewater treatment systems are also available. The systems include an initial primary component involving both physical and chemical treatment to reduce suspended solid materials. A second component includes a biological treatment of the wastewater to remove dissolved organic substances followed by a third step or component to remove bacteria and/or other microbes. This final step may involve one or more of the following treatments: chlorination, ultraviolet radiation or ozonation.
Those three primary alternatives for water/wastewater disinfection all suffer from one or more serious limitations:
1. Chlorination and Its Variants (Chlorine Dioxide, et al.)
In drinking water, chlorination often results in the formation of various organic chlorination byproducts which have been shown to cause cancer and birth defects in children. Also, chlorination at non-toxic dosage levels, is not capable of inactivating Cryptosporidium, a major disease-causing parasite.
In wastewater treatment, chlorination must be followed by dechlorination using sulfur dioxide or an equivalent chemical to comply with discharge chlorine levels. In combination, it is a costly process. Also, recent OSHA regulations establish tight controls for operator safety, and security, storage, and handling of chlorine gas is problematic.
2. Ultraviolet Radiation (UV)
While UV disinfection systems offer the primary current alternative to chlorination, they also have serious limitations. In large pipe/channel disinfection systems, they do not effectively scale up and provide the required disinfection. Also, in high turbidity water or wastewater, disinfection action is erratic and unpredictable due to absorption and scattering of the efficacious light.
Gorski Stephen H.
Schlager Kenneth J.
Bioelectromagnetics, Inc.
Godfrey & Kahn, s.c.
Phasge Arun S,.
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