Enhanced Electro-Oxidation System

Abstract

A method for treating a quantity of water containing a first level of contaminants and discharged from a process includes mixing the water with wastewater having a second level of contaminants and producing a condensate having a third level of contaminants, the second level being higher than the first level. The method further includes passing the condensate through a reverse osmosis system to produce a permeate having a fourth level of contaminants and a concentrate having a fifth level of contaminants higher than the fourth level. The method also includes oxidizing the concentrate in an electro-oxidation system to produce wastewater and directing the wastewater to a point upstream of the reverse osmosis system to perform the mixing step.

Description

[Background technology]

[0001] Water sources, such as surface water, wastewater, process water, and drinking water, often contain undesirable contaminants. These contaminants can result in or contain compounds with high chemical oxygen demand (COD), harmful inhibitory, and / or biodegradable chemicals that are extremely difficult to treat. Many of these compounds are dangerous even at low concentrations (e.g., ppm, ppb, ppt). The reaction kinetics and stoichiometry required to destroy or remove these types of contaminants are typically not economically advantageous. The most troublesome compounds include, for example, PFAS, dioxins, pesticides, and active pharmaceutical ingredients. Standard biological wastewater treatment technologies cannot effectively treat these compounds, and standard advanced oxidation processes are either too inefficient or too costly. Summary of the Invention

[0002] In one aspect, a treatment system operable to treat a water stream includes a reverse osmosis system operable to separate the water stream into a permeate having a first level of contaminants and a concentrate having a second level of contaminants higher than the first level of contaminants. An electro-oxidation system is disposed to receive the concentrate and operates to reduce the level of contaminants in the concentrate using an electro-oxidation process and to discharge an effluent having a third level of contaminants lower than the second level of contaminants. A wastewater return line is disposed to direct wastewater from the electro-oxidation system to an inlet to the reverse osmosis system, where the wastewater mixes with the water stream before entering the reverse osmosis system.

[0003] In another aspect, a method for treating a quantity of water discharged from a process includes mixing the water with wastewater to produce a condensate, directing the condensate to a reverse osmosis system, and separating the condensate into a permeate having a first level of contaminants and a retentate having a second level of contaminants higher than the first level of contaminants. The method also includes directing the condensate to an electro-oxidation system and applying an electric current to the condensate to oxidize a portion of the contaminants to produce wastewater having a third level of contaminants lower than the second level of contaminants. The method further includes directing the wastewater to a point upstream of the reverse osmosis system.

[0004] In another aspect, a method for treating a quantity of water containing a first level of contaminants and discharged from a process includes mixing the water with wastewater having a second level of contaminants to produce a condensate having a third level of contaminants, the second level being higher than the first level. The method further includes passing the condensate through a reverse osmosis system to produce a permeate having a fourth level of contaminants and a concentrate having a fifth level of contaminants higher than the fourth level. The method also includes oxidizing the concentrate in an electro-oxidation system to produce wastewater and directing the wastewater to a point upstream of the reverse osmosis system to perform the mixing step.

[0005] To easily identify the discussion of a particular element or act, the most significant digit or digits of a reference number refer to the figure number in which that element is first referenced. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of an electro-oxidation system.

[0007] [Figure 2] 1 is a schematic diagram of an enhanced electro-oxidation treatment system. DETAILED DESCRIPTION OF THE INVENTION

[0008] Before describing any embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth herein or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0009] Various technologies relating to systems and methods will now be described with reference to the drawings, wherein like reference numerals represent like elements throughout. The drawings described below and the various embodiments used to illustrate the principles of the present disclosure in this patent document are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It will be understood that functions described as being performed by a particular system element may be performed by multiple elements. Similarly, for example, an element may be configured to perform functions described as being performed by multiple elements. Numerous innovative teachings of the present application will be described with reference to exemplary, non-limiting embodiments.

[0010] The terms used herein should be construed broadly unless expressly limited in some instances. For example, "including," "having," and "comprising," as well as their derivatives, mean inclusion without limitation. The singular forms "a," "an," and "the" are intended to include the plural unless the context clearly indicates otherwise. Also, the term "and / or," as used herein, refers to and includes any and all possible combinations of one or more of the associated listed items. The term "or" is inclusive, meaning and / or, unless the context indicates otherwise. The terms "associated with" and "associated with," as well as their derivatives, can mean including, contained within, interconnected, containing, contained within, connected to or connected with, fitting into, communicable with, associated with, interconnected, juxtaposed, adjacent to, coupled to or coupled with, having, having the property of, and the like. Furthermore, although multiple embodiments or structures may be described herein, features, methods, steps, components, etc. described with respect to one embodiment apply equally to other embodiments unless specifically stated to the contrary.

[0011] Additionally, although terms such as "first," "second," and "third" may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather, these numerical adjectives are used to distinguish between different elements, information, functions, and acts. For example, a first element, information, function, or act could be referred to as a second element, information, function, or act, and similarly, a second element, information, function, or act could be referred to as a first element, information, function, or act without departing from the scope of the present disclosure.

[0012] Additionally, the term "adjacent to" can mean that an element is relatively close to, but not touching, another element, or that an element is touching another portion, unless the context clearly indicates otherwise. Additionally, the phrase "based on" is intended to mean "based, at least in part on," unless expressly stated otherwise. Terms such as "about" or "substantially" are intended to cover variations in values ​​that are within normal industry manufacturing tolerances for that dimension. In the absence of an industry standard, a 20% variance is included within the meaning of these terms unless otherwise specified.

[0013] The system of Figure 1 can be implemented to effectively treat groundwater, surface water, and water generated from natural, industrial, or chemical processes, such as refineries and petrochemical plants. Figure 1 illustrates an electro-oxidation system 100 that uses electricity to directly generate hydroxyl radicals in spent caustic for oxidation. The electro-oxidation system 100 illustrated in Figure 1 includes a pump 102, a filter 104, a cooler 106, a power supply 108, and a reactor 110. Of course, some of the components illustrated in Figure 1 may be omitted depending on the system.

[0014] Pump 102, if employed, may include any type of pump operable to draw fluid from inlet 112 or source and direct the fluid through electro-oxidation system 100 at a desired flow rate and pressure. Filter 104 may be positioned to filter large contaminants and debris from the fluid before it passes through cooler 106. Cooler 106 operates to cool the fluid to a desired temperature before it is directed to reactor 110.

[0015] The reactor 110 shown in Figure 1 uses conductive, freestanding, substrate-free synthetic diamond electrodes to generate hydroxyl radicals directly in water or a fluid, although other configurations are possible. Electric current is supplied to the electrodes by a power source 108. As with other oxidation techniques, the current completely destroys a portion of the contaminants to their highest oxidation state. The degree of COD (chemical oxygen demand) reduction directly corresponds to the current density and the operating time of the electro-oxidation system 100. Operating costs (primarily electricity costs) are stoichiometrically related to the amount of COD destruction. Hydroxyl radicals (oxidants) are generated by splitting water into -OH radicals and H+ ions using electricity and electrodes. The electro-oxidation system 100 shown in Figure 1 may incorporate one or more boron-doped diamond (BDD) electrodes within the reactor 110.

[0016] The treatment system 200 of Figure 2 can be used in conjunction with the electro-oxidation system 100 of Figure 1 to further enhance the effectiveness of contaminant removal. The electro-oxidation of organic compounds is mass-transfer limited. In other words, the lower the concentration of organic contaminants requiring oxidation, the more time and energy (lower efficiency / higher cost) required to achieve the desired oxidation. Furthermore, low or non-conductive wastewater significantly reduces the electrical efficiency of electro-oxidation.

[0017] Treatment system 200 includes electro-oxidation system 100 and reverse osmosis system 202. Reverse osmosis system 202 includes one or more membranes that concentrate salts and contaminants (total dissolved solids (TDS)) in water stream 204 (input) into a smaller portion of the wastewater. This has the effect of increasing the concentration of TDS by 5 to 30 times its original concentration while proportionally reducing the volume of water containing TDS. This allows a much smaller wastewater stream with a much higher concentration of contaminants to be treated, thus improving the efficiency or effectiveness of electro-oxidation system 100.

[0018] In operation, a condensate stream 204 is supplied from a wastewater source or process to a reverse osmosis system 202. The reverse osmosis system 202 operates to separate a permeate 206 from a retentate 208. The permeate 206 has a very low TDS and very low levels of undesirable contaminants, and typically comprises 75-90 percent of the condensate stream 204. In the example of Figure 2, the contaminants include dioxane, and the permeate 206 has a level of dioxane of less than 5 ppd.

[0019] The concentrate 208 comprises the remainder of the condensate stream 204 (10-25% of the condensate stream 204) and is directed to the electro-oxidation system 100, which operates as described with respect to Figure 1. For the electro-oxidation system 100 to operate, the concentrate 208 must be conductive. To ensure this, salt (e.g., NaCl) is added to the electro-oxidation system 100 via a salt make-up connection, as needed, to maintain the desired conductivity level.

[0020] During operation, the electro-oxidation system 100 oxidizes contaminants, producing a less polluted fluid and one or more gases (e.g., carbon dioxide, carbon monoxide, hydrogen, etc.) that can be recovered, burned, or simply vented to the atmosphere. The reduced polluted fluid is then returned to the condensate stream 204 via the wastewater return line 210. The fluid still contains contaminants, and when mixed with the condensate, serves to increase the contamination level, improving the effectiveness of the treatment system 200.

[0021] In this manner, the conductive salts and untreated contaminants in the wastewater return line 210 are sent back to the feed side of the reverse osmosis system 202 to be recycled / reconcentrated for further processing in the electro-oxidation system 100 .

[0022] This treatment system 200 improves the efficiency of the electro-oxidation process, shortening the time required to achieve oxidation and using less power to achieve the same amount of oxidation. This also has the advantage of allowing for smaller equipment size for a given operation. Furthermore, as previously mentioned, non-conductive wastewater requires the addition of conductive salts, which are typically sent along with the oxidized wastewater. Using membrane separation (reverse osmosis system 202), the salts can be recovered and reused. This reduces TDS and sulfates, which can be sensitive to some downstream wastewater treatment systems.

[0023] While exemplary embodiments of the present disclosure have been described in detail, those skilled in the art will appreciate that various changes, substitutions, variations, and improvements disclosed herein may be made therein without departing from the spirit and scope of the disclosure in its broadest form.

[0024] Nothing in this application should be read as implying that any particular element, step, act, or function is an essential element required for inclusion in the claims, and the scope of patented subject matter is defined solely by the allowed claims. Moreover, these claims are not intended to be interpreted as a means-plus-function claim unless followed by the precise words "means for."

Claims

1. 1. A treatment system operable to treat a stream of water, comprising: a reverse osmosis system operable to separate the water stream into a permeate having a first level of contaminants and a concentrate having a second level of contaminants higher than the first level of contaminants; an electro-oxidation system disposed to receive the concentrate and operable to reduce the level of the contaminants in the concentrate using an electro-oxidation process and to discharge wastewater having a third level of the contaminants that is lower than the second level of the contaminants, the electro-oxidation system including a freestanding synthetic boron-doped diamond electrode; and a wastewater return line positioned to direct the wastewater from the electro-oxidation system to an inlet of the reverse osmosis system, the wastewater being mixed with the water stream before entering the reverse osmosis system; Equipped with Processing system.

2. 2. The treatment system of claim 1, wherein said contaminant comprises dioxane and said first level is between 0 and 5 ppb.

3. 10. The treatment system of claim 1, further comprising a salt make-up connection operable to supply salt to said electro-oxidation system.

4. 1. A method for treating a quantity of water discharged from a process, comprising: mixing said amount of water with the wastewater to produce a condensate; directing the condensate to a reverse osmosis system; separating the condensate into a permeate having a first level of contaminants and a concentrate having a second level of contaminants higher than the first level of contaminants; directing the concentrate into an electro-oxidation system; applying an electric current to the concentrate via a freestanding synthetic boron-doped diamond electrode to oxidize a portion of the contaminants to produce the wastewater having a third level of the contaminants that is lower than the second level of the contaminants; and directing the wastewater to a point upstream of the reverse osmosis system to perform the mixing step; method.

5. 5. The method of claim 4, further comprising adding salt to the electro-oxidation system to increase the electrical conductivity of the concentrate.

6. 6. The method of claim 5, wherein the reverse osmosis system removes a portion of the salts from the wastewater, and the electro-oxidation system redirects a portion of the removed salts to maintain the conductivity of the concentrate at a desired level.

7. 5. The method of claim 4, wherein the contaminant comprises dioxin and the first level of dioxin is 0 to 5 ppb.

8. 1. A method for treating a quantity of water containing a first level of contaminants and discharged from a process, comprising: mixing the amount of water with wastewater containing a second level of contaminants to produce a condensate containing a third level of contaminants, the second level being greater than the first level; passing the condensate through the reverse osmosis system to produce a permeate having a fourth level of the contaminants and a concentrate having a fifth level of the contaminants greater than the fourth level; applying an electric current to the concentrate through a freestanding synthetic boron-doped diamond electrode to oxidize the concentrate in an electro-oxidation system to produce the wastewater; and directing the wastewater to a point upstream of the reverse osmosis system to perform the mixing step; method.

9. 9. The method of claim 8, wherein the oxidizing step further comprises applying an electric current to the concentrate to oxidize a portion of the contaminants.

10. 10. The method of claim 8, further comprising adding salt to the electro-oxidation system to increase the electrical conductivity of the concentrate.

11. 11. The method of claim 10, further comprising removing a portion of the salts from the wastewater in the reverse osmosis system and redirecting a portion of the removed salts to the electro-oxidation system to maintain the conductivity of the concentrate at a desired level.

12. 9. The method of claim 8, wherein the contaminant comprises dioxin and the second level of dioxin is 0 to 5 ppb.

13. 9. The method of claim 8, wherein the levels of contaminants decrease in the following order from highest to lowest: fifth level, second level, third level, first level, fourth level.

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