Patent Application
20080272050
The present disclosure relates generally to purification systems and methods, and more particularly to chemical-free systems and methods for purifying contaminated fluids using a multiple barrier approach.
Since almost all forms of life need water to survive, the improvement of water quality in decontamination systems has typically been a subject of significant interest. As a result, treatment systems and techniques for removing contaminants from contaminated fluids have been developed in the past. Prior approaches have included water treatment by applying various microorganisms, enzymes and nutrients for the microorganisms in water. Other approaches involve placing chemicals in the contaminated fluids, such as chlorine, in an effort to decontaminate supplies. Some such systems have proved to be somewhat successful; however, severe deficiencies in each approach may still be prominent.
In some prior systems, solid reactants are used that have to be dissolved or dispersed prior to use, or were cumbersome and not particularly suited for prolonged water treatment, or could not be used in a wide variety of different types of applications. In particular, the handling of the solid reactants often posed problems with respect to different dissolution rates, concentrations and growth rates. In addition, in systems employing chemical additives, the resulting “decontaminated” fluid may actually now be contaminated by these chemicals, in spite of having removed the original biological or other contaminants from the media. Even in systems employing microfiltration, problems with the system may not be from any sort of additive, but instead may simply be the clogging of the filter elements or membranes with foulants accumulated from the decontamination process. Time-consuming filter cleaning processes combined with system downtime can become costly and inefficient for purification companies.
Some more advanced treatment systems and techniques include treatments using a photolytic or a photocatalytic process. Common photocatalytic treatment methods typically make use of a technique by which a photocatalyst is bonded to contaminants in order to destroy such biomaterials. Specifically, photocatalytic reactions are caused by irradiating electromagnetic radiation, such as ultraviolet light, on the fixed photocatalyst so as to activate it. Resulting photocatalytic reactions bring about destruction of contaminants, such as volatile organic contaminants or other biologically harmful compounds that are in close proximity to the activated photocatalyst. However, employing such photocatalytic systems alone may be ineffective for use in 100% recycle closed-loop systems, or may impose equipment size or cost restrictions for some applications.
Accordingly, the search has continued for chemical-free decontamination systems and processes that may be employed for closed-loop, 100% product recovery systems, but that do not suffer from the deficiencies found in conventional approaches.
Systems and methods constructed and operated in accordance with the principles disclosed herein integrate, in some embodiments, ultraviolet (UV) radiation in an advanced oxidation process (AOP), and a honing material, along with a cross-flow membrane filter technology into a single closed-loop system. In exemplary embodiments, the disclosed approach combines the advantages of chemical-free AOP technology, long-life wiper-free UV disinfections, and maintenance-free ceramic MF/UF membranes to provide durable multi-barrier decontamination and protection for potable drinking water or any type of contaminated water. Such systems and methods provide a 100% fluid recovery system (i.e., zero reject stream) without the use of aggressive oxidants (such as hydrogen peroxide and ozone) added to the system. Such a combination has not been provided in conventional approaches, and thus the disclosed systems and processes provide enhanced performance over the sum of the individual technologies.
In one aspect, a closed-loop system for decontaminating a contaminated fluid is provided. In one embodiment, the system comprises a filtration membrane. In addition, the system could comprise a honing material located in the contaminated fluid that is sufficient to scrub foulants from the filtration membrane, as well as other system components, as the contaminated fluid is filtered by the filtration membrane. Also, in such embodiments, the system comprises an Advanced Decontamination Process sufficient to destroy or otherwise eliminate, by oxidation or reduction, biological and organic contaminants from the contaminated fluid.
In another aspect, a method of decontaminating a contaminated fluid within a closed-loop system is provided. In one embodiment, the method comprises passing the contaminated fluid through a filtration membrane. In addition, such a method could comprise providing a honing material in the contaminated fluid, where the honing material is sufficient to scrub foulants from the filtration membrane, as well as other system components, as the contaminated fluid is passing through the filtration membrane. Furthermore, such a method could comprise performing an Advanced Decontamination Process on the contaminated fluid sufficient to destroy, by oxidation or reduction, biological and organic contaminants from the contaminated fluid.
In yet another aspect, a more specific closed-loop system for decontaminating a contaminated fluid is provided. In one embodiment, such a system comprises a cross-flow filtration membrane, and a photocatalytic slurry placed in the contaminated fluid. The photocatalytic slurry has a texture that is sufficient to scrub foulants from the filtration membrane as the contaminated fluid is filtered by the filtration membrane, as well as from other system components. In addition, in such embodiments, the system further includes a UV light source providing a photolytic reaction sufficient to disinfect contaminants in the contaminated fluid. Still further, in such an embodiment the system could also include an Advanced Decontamination Process comprising a photocatalytic reaction, caused by the UV light source, between the photocatalytic slurry and contaminants in the contaminated fluid sufficient to oxidize and thereby destroy biological and organic contaminants in the contaminated fluid.
Embodiments are illustrated herein by way of example in the accompanying figures, in which like reference numbers indicate similar parts, and in which:
Referring initially to
The contaminated fluid 110 is transferred, via a pump 120, to a filtration member 130. Specifically, the contaminated fluid 110 is pumped through a cross-flow filter 130 for filtering out contaminants in the fluid. In some embodiments, the cross-flow filter 130 is a membrane filter, such as a ceramic membrane. The advantages of a ceramic membrane are the durability of such membranes, as well as their ability to filter out very small contaminants. In such conventional systems 100, the cross-flow filter 130 filters the contaminates so that the filtered fluid, or permeate 140, may be collected. The filtered contaminants are expelled from the system 100 as reject 150. The reject 150 must then be collected and properly disposed of
Turning now to the
In these types of systems 200, filtration of the contaminated media 210 may be performed using cross-flow filtration with basically no fouling of the membrane 230 in the system 200, but also with no reject from the system 200. As the closed-loop system 200 filters the contaminated fluid 210, permeate 240 is collected from the system 200. Fluid that still contains some contaminants is recycled back to the contaminated media 210 source via a recycle loop.
However, some embodiments require the contaminant itself to help maintain the cross-flow filter membrane 230 clean. For example, such a system 200 functions relatively well where the contaminated media 210 is populated with aggregate fines. Such applications may include the collection of water from a quarry, where the water is used to assist in the cutting of certain stone (e.g., limestone). Fine particles of the stone (i.e., the aggregate fines) collect in the water, and that now-contaminated water may need to be filtered. In such a system, two protection barriers are present: (1) the aggregate fines are a honing material, and (2) pH in limestone and similar aggregate fines is very basic (very high). Thus, in such closed-loop systems 200 where the contaminant is not a biological or organic contaminant, two barriers help to keep the cross-flow membrane 230 clean:
In other embodiments, the contaminant itself does not provide the honing capabilities. As a result, a honing material 250 may be added to the system 200 to provide this benefit. Moreover, the added honing material 250 may also provide the higher pH level desired, again if the contaminant itself does not provide it.
The addition of a UV reactor 260 may help maintain the cleanliness of the cross-flow filter membrane 230 even further. The addition of UV light to the contaminated fluid 210 can help disinfect the fluid within the closed-loop. However, even in such a system, the aggregate fines or other contaminants are not a photocatalyst. Therefore, an advanced decontamination process (e.g., decontamination by oxidation) is not provided in the closed-loop of the system 200. As a result, even the benefits of the UV reactor 260 are limited in such embodiments. Thus, for the system illustrated in
Generally, systems and methods constructed and operated in accordance with the principles disclosed herein integrate, in some embodiments, ultraviolet (UV) radiation in an advanced decontamination process and a honing material, along with a cross-flow membrane filter technology, into a single closed-loop system. In exemplary embodiments, the disclosed approach combines the advantages of chemical-free advanced decontamination technology, long-life wiper-free UV disinfections, and maintenance-free ceramic MF/UF membranes to provide durable multi-barrier protection for potable drinking water and other contaminated water/fluid sources. Such systems and methods provide a 100% fluid recovery system (i.e., zero reject stream), even without the use of aggressive oxidants (such as hydrogen peroxide and ozone) added to the system. Also, the operation of the system 300 without peroxide, ozone or other aggressive oxidants is possible, as only dissolved oxygen is needed. Of course, if the advanced decontamination process removes contaminants by reduction, then none of the above are needed. Such a combination has not been provided in conventional approaches, and thus the disclosed systems and processes provide enhanced performance over the sum of the individual technologies. In advantageous implementations, the disclosed principles may be used in the potable water market and reclaimed/reuse water market, but the disclosed technique is not limited to these markets.
In the specific embodiment illustrated in
Adding UV light from a UV reactor 360 to the photocatalytic slurry provides the advanced decontamination process, which will oxidize and thereby destroy organic, and sterilize/disinfect biological and/or organic contaminants, allowing concentrate to be continuously circulated (i.e., zero reject). Additionally, the UV reactor 360 for a photocatalytic advanced decontamination process may be located in any place in the closed-loop system 300. The UV and advanced decontamination process will destroy, by oxidation (adding electrons) or reduction (removing electrons) depending on the catalyst used in the system, biological activity and keep biomass from fouling the membrane and other system components. Thus, in such systems 300, the membrane 330 acts as an ultimate barrier for most biological species. If a slug of biological species should occur and the biomaterial is not destroyed in the advanced decontamination process subsystem, the membrane 330 will prevent the biomaterial from being discharged and will send the biomaterial back to the advanced decontamination process subsystem for another pass of treatment. This will continue until the biomaterial is destroyed and consumed or otherwise eliminated.
In sum, the honing advantage is provided by the addition of the photocatalyst in this example; thus, it works with systems where aggregate fines are not present to provide the honing portion of the filter membrane 330 (and other system components) cleaning. As a result, the three barriers provided by the exemplary system 300 illustrated in
Additionally, the system 300 in
In some embodiments, such a blowdown 370 may occur in the recycle loop of the system 300, however, such a placement is not required. Still further, the photocatalyst removed from the loop may also be regenerated. In such embodiments, little or no replacement photocatalyst needs to be purchased since the withdrawn photocatalyst is reused. Alternatively, the entire loop can be completely blown down and replaced as well, rather than a bleed and feed approach.
In addition, a fourth barrier, such as a Reverse Osmosis (or electro-dialysis or other similar) system 380 may also be added to the output of the multi-barrier system. For example, if dissolved solids in the contaminated fluid 310 are desired to be removed. Such dissolved solids may include salt, sodium, etc. Purified contaminated fluid 310 provided by the purification system 300 illustrated in
For example, in ground water systems, such as those found in parts of California, the water supply is obtained so quickly that a large concentration of sodium (e.g., 700 ppm) is often present in the drinking water. Since a typical photocatalytic system 300 as disclosed in
In conclusion, in systems implemented to decontaminate only organic or biological contaminants, then no removal of suspended solids needs to be performed. In such implementations, a 100% recycling of the fluid media is provided by the decontamination process. The system in
While various embodiments in accordance with the principles disclosed herein have been described above, it should be understood that they have been presented by way of example only, and are not limiting. Thus, the breadth and scope of the invention(s) should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.
Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, although the headings refer to a “Technical Field,” such claims should not be limited by the language chosen under this heading to describe the so-called technical field. Further, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/916,190, filed on May 4, 2007, and entitled “WATER PURIFICATION SYSTEM AND METHOD,” which is commonly assigned with the present application and incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 60916190 | May 2007 | US |
