Liquid purification or separation – Constituent mixture variation responsive
Reexamination Certificate
1999-07-16
2001-03-13
Hruskoci, Peter A. (Department: 1724)
Liquid purification or separation
Constituent mixture variation responsive
C210S103000, C210S105000, C210S143000, C210S181000, C210S192000, C210S205000, C250S436000, C250S438000, C250S437000, C422S105000, C422S111000, C422S186300
Reexamination Certificate
active
06200466
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to decontamination of water, and more particularly to methods and apparatus for decontamination of groundwater, surface water or waste water through the use of a highly efficient flashlamp or other source of high peak power, high average power, broadband, continuum output ultraviolet (UV)-rich radiation for rapidly and efficiently reducing and/or oxidizing (redox-ing) contaminants, including organic and inorganic molecules and for microbial sterilization of groundwater, surface water or waste water.
BACKGROUND OF THE INVENTION
Abundant quantities of clean, fresh water have long been available in the United States. The unfortunate introduction of pesticides, pathogens, and highly volatile gasoline components, such as MTBE, into the aquifers of many drinking water systems is now a serious constraint to economic expansion in developed countries, and a matter of survival for 20% of the world's population. As an example, the U.S. Environmental Protection Agency announced Nov. 26, 1997, that it will be issuing a new health advisory citing cancer data and drinking water contamination relating to MTBE, and will recommend maximum levels of 20-40 parts per billion in drinking water. There exists a need for cost effective method to reduce MTBE levels to meet these standards.
Current water purification technologies, including distillation, reverse osmosis, and carbon filtration usually produce suitable water quality, but their high capital, operating and maintenance costs have limited their use to only those situations where water shortages are most extreme or where cost is less important. Water contaminated with pesticide or gasoline contaminants are especially difficult and costly to remove with conventional technologies.
The $5.5 billion annual worldwide water purification market is growing, depending on market segment between 5% and 25% per year. Thirty-three percent (33% or $1.8 billion) is for purification of fresh water for commercial, industrial and residential use. Waste water reclamation and re-purification, currently about $1.0 billion annually, is the fastest growing segment. The overall market demand is currently constrained by the high cost of water purification products. Availability of low-cost alternatives could cause the market to reach $18 billion by the year 2002.
Both advantages and disadvantages of the prior art technologies are summarized below:
Vapor compression (VC), including distillation technology systems are positive on drinking water for both pathogen and chemical contamination remediation, remove total dissolved solids (TDS) and are excellent for desalinization. Drawbacks include a relatively high price, a generally large size, non portability and fairly complex construction and operation.
Reverse osmosis (RO) removes TDS with a relatively simple mechanism. Removal of non-volatile organics, pathogens is easy. However, the systems are subject to contaminating product water if feed water pressure and turbidity are out of operating parameters, involve a high price rate, does not remove dissolved organic compounds and are complex and sophisticated.
Air stripping (AS) is generally the least expensive form of water remediation and is fairly good at removing volatile organics. However, these systems are also large, very noisy and unsightly, do not remove non-volatile organics, do not remove pesticides or pathogens, depend on ancillary technology, like the use of granulated activated carbon (below), resulting in more O&M cost as well as air pollution (the volatile organics are transferred into the atmosphere).
Granulated activated carbon (GAC) acts positively on volatile and non-volatile organics like pesticides, is positive on pathogens, and can be reactivated in most cases. However, GAC also requires re-supply of heavy, bulky material, typically has a large adsorption ratio, such as about 1000 pounds GAC to 1 pound contaminant, and itself becomes a source of contamination of product water if allowed to saturate. Furthermore, saturated GAC is a hazardous waste product and must be handled as such, especially when considering issued including transportation, disposal or reactivation cost.
Low and medium pressure mercury vapor ultraviolet (UV) radiation is also effective at neutralizing pathogens, but only very slightly effective at breaking down or removing organic or synthetic organic compounds at practical flow rates. Sometimes UV is used as part of a polishing loop on larger treatment systems. However, as a practical matter, use of UV radiation in the past has been impossible. These systems are not practical for chemically contaminated water, the required low pressure lamps are typically not self cleaning, would require hundreds of lamps to equal the dosage of a lamp of the present invention, and provide a larger footprint for any type of remediation application.
Ozone saturation is effective at neutralizing pathogens and leaves no dangerous chemicals in the water. However, providing a system which injects ozone into a water supply or stream typically requires a physically rather large footprint and is complex to build and operate, involves high operation and maintenance costs, involves the production of ozone—a dangerous and reactive gas, and is not practical on chemical contaminants alone.
Finally, the use of chlorine (C
1
) is known to kill or otherwise render pathogens harmless, but has no remedial effect on chemical contaminated water except for elimination of cyanides. Current competing technologies for chemical contamination of groundwater include reverse osmosis (RO), air stripping, and Activated Carbon filtration. Although the popularity of reverse osmosis has gained substantially in market share in recent years, different technology solutions continue to dominate the various niches. RO membrane production is dominated by a few companies ( DuPont, Dow-Filmtec, Fluid Systems, Toyoba, etc.), but there are thousands of companies that act as integrators of RO systems. Few, with the notable exception of Ionics, Osmonics, and U.S. Filter exceed $100 million in revenues. Air stripping is less complicated and has low associated costs, but is noisy, unsightly, pollutes the air, and has limited effectiveness in removing MTBE to EPA standard levels. Activated Carbon Filtration involves large quantities of carbon supplied by companies like Calgon, Inc.
Pathogen removal is typically accomplished with the addition of chlorine, distillation techniques, or the use of banks of low or medium pressure ultraviolet lamps. Distillation suppliers include large European, Japanese, and Korean contractors and this technology excels at the removal of TDS. Current ultraviolet lamp suppliers include Aquafine, Fisher & Porter, and Puress, Inc. There exists a need for technology which is more energy efficient and can simultaneously remove pathogens and chemical contamination. Such equipment could also be used to post-treat water at desalination facilities to remove chemical contaminants.
Traditional UV technology relies on low and medium pressure UV lamps, similar to the fluorescent lamps used in office buildings. Medium pressure lamps operate at higher power levels than do the low-pressure lamps and, consequently, are slightly more efficient than the standard low-pressure variety. The typical low-pressure power ranges from 30 to 100 watts while the medium pressures average 3000 watts. Both lamp types are known as atomic line radiators. They produce light energy in very narrow wavelength bands at 10-20% electrical efficiency. Both types operate with A/C current and are controlled by electrical ballast.
Though the lamp life is generally very long, maintenance cost are generally very high, especially in the case of low-pressure lamps. Cleaning is the main problem. Lamps become fouled in the water environment from precipitated dissolved solids and scum. This fouling action gradually reduces the UV output making the lamp useless. Therefore, these lamps must be removed on periodic bases and manually cleaned. Further more, low and me
Hruskoci Peter A.
New Star Lasers, Inc.
Shahani, Esq. Ray
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