Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Reexamination Certificate
2000-12-07
2004-08-10
Hruskoci, Peter A. (Department: 1724)
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
C210S706000, C210S712000, C210S718000, C210S721000, C210S738000, C210S760000
Reexamination Certificate
active
06773603
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to systems for removing contaminants from liquids and, more specifically to a system for removing toxic chemicals and volatile gases (such as methyl tertiary butyl ether [MTBE], benzene, trihalomethanes, and the like), volatile chemical contaminants, pesticides, particles such as algae, other suspended organic and inorganic solids, chemicals, dissolved oils, and other particles including large and heavy particles and light, fine, or buoyant particles from water.
BACKGROUND OF THE INVENTION
This present invention relates to an improvement in a pretreatment filtration system which removes most contaminants from raw influent water before the water to be processed enters the treatment plant filtration system.
Proper water treatment and filtration are major concerns for the health and safety of all inhabitants where ever located. Improper treatment and/or disposal causes health problems, disease, and even death. The Center for Disease Control (CDC), through DNA tests, identified human sewage as the source of the 1993 Milwaukee, Wis., Cryptosporidium parvum parasite outbreak that infected over 400,000 people in that city. In the latest issue of the CDC's, Emerging Infectious Diseases Journal, the results are reported on the molecular analysis of 39 isolates of Cryptosporidium parvum from human and bovine sources in nine human outbreaks, including isolates from the 1993 Milwaukee outbreak. The new study suggests that the source of the parasite Cryptosporidium parvum in the Milwaukee outbreak is human, not bovine.
Four stool specimens were examined from the Milwaukee outbreak: three from the original outbreak and a fourth from an AIDS patient in 1996 who had initially been infected in the 1993 outbreak. All four were found only in isolates from humans. None of the four isolates were capable of producing an infection in laboratory animals.
Animal waste was also identified by DNA tests as the source of the Canadian
E. coli
outbreak that infected over 2,000 people in Walkerton, Ontario, following a summer rainstorm in May 2000. A deadly strain of
E. coli
bacteria was distributed by the Walkerton, Ontario public water supply in May, killing six people and infecting 2,000 others. New Canadian regulations were passed forcing municipalities to ensure the water is safe and to thereby prevent any recurrence.
Canadian municipalities must release their first public water quality reports by Oct. 30, 2000. Municipalities that violate the rules face fines ranging from $20,000 to $2 million. Jail sentences can also be imposed. This new regulation establishes tougher drinking water standards and policies that reflect the most current expertise and procedures in drinking water protection. Additionally, the U.S. Consumer Confidence Report requires every public water utility to distribute a detailed analysis of the chemicals, parasites, bacteria and virus in their public water supply for the previous year to all homeowners. These water quality reports are increasing the demand for better technology that works.
All public water districts using surface water must install filtration equipment and hire a State certified grade-3 plant operator by the year 2003, which is the Clean Water Act regulations deadline for small water districts. The largest immediate market for pre-filtration systems are in those states with the highest number of small water districts using surface water. Efficient and effective pre-filtration systems are a mandated necessity under current regulations/requirements. The pre-filtration system of the present invention meets, and exceeds, the challenges imposed by these regulations/requirements and far surpasses current pre-filtration systems in that challenge.
Water supplies for domestic drinking water, process water for chemical plants, or other liquids are often contaminated with a variety of contaminants, such as, but not limited to, toxic chemicals, volatile chemical contaminants (such as MTBE, benzene, perchlorate, trihalomethanes, and the like), pesticides, particles such as algae, other suspended organic and inorganic solids, dissolved oils, and other particles including large and heavy particles and light, fine, or buoyant particles (referred to collectively as contaminants). These contaminants must be removed in a reliable and cost-effective, cost-efficient manner.
The pre-filtration water decontamination system of the present invention was designed to remove most of the organic suspended solids (such as, but not limited to, algae), and volatile toxic chemicals from the raw influent water before it enters a final-stage treatment plant filtration system. Pre-filtration is necessary for a more efficient operation of the final-stage filtration. Common pre-filtration systems include use of sand filters, membrane filters, chemical flocculation-sedimentation-filtration (settle-to-the-bottom method), and large tank-type dissolved air flotation (DAF) systems. These systems and methods do work at pre-filtration but are not as effective nor as efficient as is necessary for proper pre-filtration.
Many older water treatment plants use gravitational separation methods, typically in sedimentation systems or dual-media sand filtration systems that may not be acceptable under the newer water quality standards. In some cases, these systems can meet the standards through the use of properly mixed polymer chemical filter aids. The required expensive and complex polymer chemical mixing equipment requires constant attention, since the amount of the chemicals being added to raw water must be frequently readjusted to match the continually changing chemistry of the water being filtered. Slow sand filters require a considerable investment, but generally can be operate for longer periods without cleaning. Unfortunately, even with pretreatment, both dual-media and slow sand filters fail to meet water quality standards for hours or several days after each backwash cleaning. Ordinary sand filters become overwhelmed after every rainstorm. Membrane filters, which generally are more efficient than sand filters, quickly clog and require constant attention whenever it rains. The system of the present invention actually becomes more efficient when turbidity increases.
Ordinary chemical flocculation and sedimentation processes are slow, require chemicals, and their maintenance is high. Moreover, they do not prevent toxic chemicals, pesticides and algae from passing through the ordinary filter bed. If algae spores, for example, are present when chlorine is added, toxic disinfection byproducts are formed, which is highly undesirable and a violation of the USEPA Safe Drinking Water Act. The inability of older municipal filtrations systems to remove algae is apparent in the lack of clarity found when a swimming pool is filled with “clean” tap water. Most pool contractors have to shock tap water with large doses of chlorine chemical pool oxidizer to achieve the desired clear pool water appearance.
Some decontaminating systems, such as air stripping towers, currently discharge toxic chemical gases and volatile organic compounds into the atmosphere. Particulate material has also been removed from liquids by DAF floatation, another gravitational method, in which bubbles of a gas, such as air or oxygen, are introduced into the lower levels of the liquid and float to the top, carrying fine particles with them. These systems rely heavily on chemicals whereby chemical flocculates and microscopic air bubbles slowly float to the surface of a large flotation tank. This system is very costly and cumbersome requiring chemical mixers to blend flocculating chemicals such as alum (aluminum) with the raw influent before it enters a main tank. A large impeller pump injects high-pressure water containing excess dissolved air through an array of jet nozzles in the bottom of the tank. Mechanical scrapers push the float particles into a trough for removal and dewatering. These are relatively inefficient, in light of the outbreaks above-described, costly to operat
Lodico Joseph T.
Moorehead Jack
Coverstone Thomas E.
Hruskoci Peter A.
Intellectual Capital Enterprises, Inc.
Townsend & Townsend & Crew LLP
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