Patent Application
20070199904
The present invention relates to methods for detecting organic matter in and purifying liquids, and more particularly to methods for reducing and/or eliminating organic matter in liquids such as water. The invention further relates to systems for effecting and monitoring the extent of such treatment of organic matter.
Water and other liquid treatment methodologies and systems have been developed and implemented over a wide range of applications. Most typically, such purification efforts are focused on water at either or both of feed streams and waste streams from a variety of processes. In many cases, a high level of purity at the feed side of the process is desired so as to minimize or eliminate process variables or inaccuracies introduced by impurities. Examples of applications that seek or require purified liquids, and particularly purified water, include semi-conductor manufacturing, food and beverage manufacturing, laboratory uses, medical germicidal uses, and analytical chemistry applications. Total organic and inorganic treatment and detection systems purify the liquid and analyze the byproducts.
In applications seeking to remove organic matter from liquid water or water vapor, certain treatment agents are widely recognized as being useful in destroying the organic matter. Such treatment agents include, for example, ultraviolet radiation, hydrogen gas with an oxidizer, ozone gas, chlorine, and other chemical treatment agents. Ultraviolet radiation, for example, treats organic matter in water through two primary methods. For example, certain wavelength radiation within the ultraviolet band excites carbon-carbon bonds to a point wherein the bonds are broken, leaving molecules that are sufficiently volatile to form gas at room temperature. Ultraviolet radiation is further known to break up water molecules into OH radicals. The oxidizing radicals created by the ultraviolet radiation then attack organic matter in the water to create CO2 and H2O, with the carbon dioxide forming a gas at room temperature. Ultraviolet radiation wavelengths of 185 nm and 254 nm are known to have the above effects on organic and water molecules. There are many other combinations of treatment agents and other mechanisms for creating and/or introducing oxidizing reagents in water.
The treatment of organic matter in water through the use of ultraviolet radiation and a photo-reactive oxidizer is preferred due to the fact that the reaction tends to have a higher degree of completion, and the products created in such treatment are environmentally friendly. For example, ozonation of organic matter in water produces carbon dioxide and water. In many applications, however, process feed streams are desired to be free of entrained fixed gases or free of inorganic carbon. Such applications include, for example, semi-conductor manufacturing, TOC detection, and liquid chromatography, wherein even small amounts of dissolved gases can interfere with the accuracy and quality of the results obtained. Accordingly, feed streams to such applications must be degassed prior to utilization. Such degassing is particularly germane where organic matter treatment of the feed stream has been conducted through techniques adding or developing gaseous species thereto, as described above.
The semi-conductor manufacturing industry is an example application that has long utilized a plurality of process steps to purify and degas liquid feed streams. Such process steps are conventionally accomplished in distinct apparatus. For example, conventional systems incorporate a first apparatus for treating organic matter in e.g. water, and then involve a second distinct apparatus to degas the feed stream once organic matter treatment has taken place. Typically, feed streams are treated to remove organic matter by being transported in quartz tubing, such that ultraviolet radiation may penetrate into the liquid and subsequently destroy the organic matter. The quartz containers transporting the feed stream through the ultraviolet radiation zone, however, maintain all gaseous reactants and products within the liquid stream, as the quartz is substantially liquid and gas impermeable. The feed stream must therefore be subsequently passed to a separate degassing apparatus for removal of reactant and product gases prior to utilization of the liquid feed stream in the given process.
It is therefore a principal object of the present invention to provide a single liquid treatment apparatus that both treats organic matter in the liquid and removes gases therefrom, so as to provide outlet liquid that is both purified and degassed.
It is a further object of the present invention to provide a method for treating organic matter in a liquid stream flowing through fouling and degradation-resistant polymeric material that is substantially gas-permeable and liquid-impermeable, and transparent to ultraviolet radiation.
It is a still further object of the present invention to provide a treatment chamber for treating organic matter in liquid, which chamber introduces into the liquid one or more organic matter treatment agents, and has an environment conducive to removing gases from the liquid through a gas-permeable, liquid-impermeable polymeric conveyance member.
It is a yet further object of the present invention to provide a vacuum degassing chamber that is resistant to photolysis, and through which treatment liquid is conveyed, and in which one or more organic matter treatment agents are deployed to treat organic matter in the liquid.
By means of the present invention, a method for treating organic matter in a liquid stream is provided in a single apparatus. The organic matter treatment is facilitated by the conveyance of the organic matter-containing liquid through a treatment chamber within an inert and fouling-resistant polymeric conveyance member. Such polymeric material is both transparent to ultraviolet radiation and gas-permeable and substantially liquid-impermeable, so as to enable penetration of organic matter treatment agents through a barrier wall of the conveyance member into the liquid stream while acting as an effective vessel for such liquid. In addition, the gas-permeable characteristics of the conveyance member enables the treatment chamber to effect a degassing mechanism on the contained liquid, such that the liquid is both purified and degassed prior to exiting from the treatment chamber. The degassing mechanism is brought about by differentials in partial pressures of respective product gases in the liquid stream, as compared to such partial pressures in the treatment chamber external to the liquid conveyance member. By Henry's Law of Partial Pressure, target gas species may be removed from the liquid stream by maintaining the environment within the treatment chamber and external to the liquid conveyance member at target gas partial pressures lower than such partial pressures in the liquid stream. Such an environment may be accomplished through the utilization of a sweep fluid or of an at least partially evacuated treatment chamber.
A plurality of chambers can be connected together to aid the measurement of entrained gases separate from introducing oxidizing agents to dissolved organic matter in water and subsequently measuring reaction byproducts.
In a particular embodiment, the method for treating organic matter in a liquid includes transporting the organic matter-containing liquid through a conveyance member that is substantially gas-permeable and liquid-impermeable, and introducing to the liquid an organic matter treatment agent while the liquid is disposed in the conveyance member. The method further provides removing one or more product gases from the liquid through a wall of the conveyance member, with the one or more product gases being disposed in the liquid as a consequence of the treatment of the organic matter by the treatment agent.
A further embodiment of the present invention includes providing a treatment chamber having one or more liquid conveyance members passing therethrough, which liquid conveyance members are substantially gas-permeable and liquid-impermeable. The liquid is transported in the liquid conveyance member through the treatment chamber where the liquid is introduced to an organic matter treatment agent. One or more product gases are then removed from the liquid through a wall of the conveyance member, wherein the one or more product gases are disposed in the liquid as a consequence of the treatment of the organic matter by the treatment agent.
An additional embodiment of the invention provides a system for treating organic matter in a liquid, with the system including a chamber having inlet and outlet connections for admitting and discharging the liquid to be treated. A gas-permeable, liquid-impermeable conveyance member conducts the liquid through the chamber between the inlet and outlet connections. The system further includes an organic matter treatment agent dispensing device for introducing the liquid to one or more organic matter treatment agents, such that one or more product gases are developed in the liquid to respective first partial pressures as a result of the treatment of the organic matter by the one or more organic matter treatment agents. The volume within the chamber external to the conveyance member has respective second partial pressures of the one or more product gases that are lower than corresponding first partial pressures of such product gases so as to remove the one or more product gases from the liquid through an outer wall of the conveyance member. The treatment agents may optionally be placed in the conduit member upstream and downstream to facilitate purification or conversion of organic matter into inorganic matter. The agents may also be introduced as a liquid prior to the chamber through a dosing valve.
The objects and advantages enumerated above together with other objects, features, and advances represented by the present invention will now be presented in terms of detailed embodiments described with reference to the attached drawing figures which are intended to be representative of various possible configurations of the invention. Other embodiments and aspects of the invention are recognized as being within the grasp of those having ordinary skill in the art.
With reference now to the drawing figures, and first to
Preferably, system 10 further includes an organic matter treatment agent dispensing device 22 for introducing the liquid within conveyance member 18 to one or more organic matter treatment agents. A variety of organic matter treatment agents may be utilized in the systems and methods of the present invention, with the purpose of such agents being to breakdown and/or destroy relatively long-chain organic molecules in the liquid stream. Typically, molecules having at least four carbon atoms are in liquid or solid state at feed or waste stream temperatures, such as ambient room temperature. Such materials, therefore, must be treated in some fashion before being removed from the liquid process stream in a gaseous state.
For the purposes of the present invention, treatment agents which cause the breakdown and/or destruction of organic matter molecules without substantial heating of the liquid process stream is desired. Accordingly, known organic matter treatment agents such as ultraviolet radiation and ozone gas are examples of effective mechanisms by which to treat organic matter. Dispensing device 22, therefore, preferably emits or deploys organic matter treatment agents into the liquid that is conveyed within the confines of chamber 12. Dispensing device 22 may, for example, comprise one or more ultraviolet radiation lamps and/or ozone gas vents that are directed toward conveyance member 18. The ozone gas may either be generated at dispensing device 22, or at a remote location and subsequently transported to dispensing device 22 for deployment within chamber 12.
In preferred embodiments, dispensing device 22 may be positioned adjacent inlet connection 14, such that treatment of organic matter in the liquid stream begins as soon as the liquid has entered chamber 12 within conveyance member 18. In doing so, the organic matter treatment agents deployed by dispensing device 22 operably act upon the organic matter at the early stages of the liquid passage through chamber 12. In some embodiments, additional organic matter treatment agents may be added to the liquid stream at locations upstream from inlet connection 14 of chamber 12 so as to enhance the effectiveness of the organic matter treatment agents deployed by dispensing device 22. A particular example of such an embodiment is in the addition of ozone gas to the liquid stream prior to chamber 12, with dispensing device 22 comprising ultraviolet radiation lamps, which further activate the ozone gas within the liquid stream in conveyance member 18 to treat organic matter therein.
Preferably, conveyance member 18 is fabricated from a substantially gas-permeable, liquid-impermeable material. An example of such a material is a copolymer of perfluoro-2,2-dimethyl-1,3-dioxole (“PDD”). In some embodiments, the copolymer is a dipolymer of PDD and a complimentary amount of tetrafluoroethylene (“TFE”), which is available from E.I. Du Pont De Nemours and Company of Wilmington, Del. under the trade name Teflon AF®. This material may be formed through extrusion or other processes into various configurations including tubing for conveying liquid therethrough, such as in conveyance member 18 of the present invention. As formed, the PDD-TFE polymeric material constitutes a non-porous membrane that is gas-permeable and liquid-impermeable, and is also resistant to fouling. Moreover, in its base form, such a polymeric material is substantially transparent to ultraviolet radiation or has light guiding properties. As such, ultraviolet light emitted external to conveyance member 18 can interact with the conveyed liquid and/or an organic matter treatment agent within the liquid so as to treat the organic matter. Although Teflon AF® has been described above as being a particularly preferred material for use in constructing conveyance member 18, the use of other gas-permeable, liquid-impermeable materials are contemplated by the present invention. Examples of such alternative materials include expanded FEP and expanded porous PTFE.
As shown in the embodiment illustrated in
System 10 of the present invention preferably enables and accomplishes removal of such product gases from the liquid stream transported through chamber 12 by conveyance member 18. System 10 of the present invention utilizes Henry's Law of Partial Pressure to draw gaseous species from a relatively high partial pressure within the liquid stream to a relatively low partial pressure external to conveyance member 18. The difference in respective partial pressures may be referred to as a partial pressure potential. Preferably, such a partial pressure potential is generated for each of the gaseous species disposed in the liquid stream that are desired to be removed prior to exiting out from chamber 12 at outlet connection 16. Partial pressure potential (ΔP) is described by the following relationship:
ΔP=PAL−PAZ
In order for gaseous species “A”, for example, to be removed from the liquid stream, the value for ΔP must be positive. In other words, the partial pressure of gaseous species A in the liquid stream must be greater than the partial pressure of gaseous species A in zone 24.
One method to accomplish a partial pressure potential is to pass a “sweep” fluid through internal volume zone 24 within chamber 12 and external to conveyance member 18, which sweep fluid contains lower partial pressures of the respective product gases than the corresponding product gas partial pressures within the liquid stream. In preferred embodiments, the sweep fluid may be nitrogen gas, though any gas or liquid may be utilized as the sweep fluid, so long as it contains the relatively low partial pressures described above.
In the embodiment illustrated in
A further mode for generating the desired partial pressure potential as described above is shown in the embodiment of
In some embodiments of the present invention, and as illustrated in
While control electronics 64 is depicted in
In some embodiments of the present invention, a photocatalyst material such as titanium dioxide or bare zirconia is disposed in or on an internal surface of conveyance member 18 so that ultraviolet radiation being utilized as the organic matter treatment agent causes the photocatalyst material to create an oxidizing reagent. The photo catalyst material may also or instead be disposed within the channel defined by conveyance member 18 in the form of a rod, thread, or other structure accessible to the ultraviolet radiation, such that the oxidizing reagent generated upon exposure to ultraviolet radiation is released to the liquid stream.
Although
The invention has been described herein in considerable detail in order to comply with the patent statutes, and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the invention as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.
