WO2013013342A1

WO2013013342A1 - Apparatus for one step removal of contaminants from aqueous system and method thereof

Info

Publication number: WO2013013342A1
Application number: PCT/CN2011/001237
Authority: WO
Inventors: Zijun Xia; Hai Yang; Caroline SUI
Original assignee: General Electric Company
Priority date: 2011-07-28
Filing date: 2011-07-28
Publication date: 2013-01-31
Also published as: TW201311572A

Abstract

An apparatus (100) configured for removing contaminants from an influent fluid stream comprises an inlet (130) and an effluent outlet (125); a flow path through which the fluid stream passes extending from the inlet (130) to the outlet (125), the flow path comprised of a first chamber (205), a second chamber (210) and a third chamber (215), these chambers (205,210,215) are coaxial; a mixing device (140) disposed in the first chamber (205) of the apparatus (100) for urging the influent fluid stream along the flow path; said first chamber (205) being defined by the inner diameter of an inner cylinder (105); and a DC power supply (305) configured to provide electric potential to said inner cylinder (105) which is used as a cathode and at least one sacrificial electrode (135) which is used as an anode, thereby creating an electrolysis chamber in said first chamber (205). And a corresponding method for removing contaminants from an influent fluid stream comprises providing said apparatus configured for treating an influent fluid stream; providing an influent fluid stream containing contaminants to said inlet; generating and extracting suspended coagulants and precipitates from the fluid stream; extracting the clarified fluid stream from the apparatus. The apparatus has lower maintenance requirements and the method is a simplified contaminant removal process.

Description

APPARATUS FOR ONE STEP REMOVAL OF CONTAMINANTS FROM

AQUEOUS SYSTEM AND METHOD THEREOF

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] This invention is related to the removal of contaminants from an aqueous system. Description of Related Art

[0002] Most effluents produced by industrial and municipal processes are required to be processed by water treatment facilities before being returned to the environment. Such facilities are typically costly to construct and operate. Further, the failure of the facility can seriously impact ongoing operations financially and in terms of operational continuity.

[0003] Electrocoagulation and effluent clarification processes for wastewater treatment are well known. However, devices for performing such processes, such as the device of Fig. 9, have heretofore required extensive maintenance and investment to assure proper operations. Moreover, some heretofore known devices have been inefficiently designed affecting both overall operation of the device and plant, as well as requiring cumbersome maintenance procedures. One example of cumbersome required maintenance is the regular replacement of fouled electrode plates in prior art devices which utilize an electrode plate bank, such as the device shown in Fig. 9. This fouling can be in the form of scale or a gelatinous film.

[0004] Further, prior art devices, such as the device shown in Fig. 9, must be periodically taken out of service in order to manually remove the precipitate from the bottom of the electrocoaguation reactor. Precipitated solids in the elecrocoagulator have to be removed out of the water in order to reuse or discharge the treated water. The removal of solids from water in prior art devices is a tedious process involving a settling device to remove large particles, and a filtration device to remove fine particles. The filtering devices are readily fouled by precipitates, thus frequent cleaning of the filtering devices is required to maintain good performance. [0005] Therefore, a need exists for an apparatus having lower maintenance requirements and a simplified contaminant removal process.

SUMMARY OF THE INVENTION

[0006] In one aspect of the invention, an apparatus configured for removing contaminants from an influent fluid stream comprises an inlet and an effluent outlet; an outer cylinder having a cylindrical top section and a frustoconical lower section; a middle cylinder disposed in the outer cylinder; an inner cylinder disposed in the middle cylinder, the inner cylinder is configured as a cathode; the outer, middle, and inner cylinders being concentric and coaxial; a flow path through which the fluid stream passes extending from the inlet to the outlet; the flow path is comprised of a first chamber, a second chamber, and a third chamber; the first chamber being defined by the inner diameter of the inner cylinder, the second chamber being defined by the outer diameter of the inner cylinder and the inner diameter of the middle cylinder, the third chamber being defined by the inner diameter of the outer cylinder and the outer diameter of the middle cylinder; at least one sacrificial electrode axially oriented in the inner cylinder for use as an anode; a DC power supply configured to provide electric potential to the inner cylinder and the at least one sacrificial electrode, thereby creating an electrolysis chamber in the first chamber; and a mixing device disposed in the inner cylinder of the apparatus for urging the influent fluid stream along the flow path.

[0007] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the first chamber in the flow path is configured to form suspended coagulants and precipitates in the fluid stream, the second chamber in the flow path is configured to grow the suspended coagulants and precipitates in the fluid stream, the third chamber is configured to cause the coagulants and the precipitates to drop out of the fluid stream.

[0008] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the flow path has a first abrupt change in direction at the transition between the first chamber and the second chamber, the flow path has a second abrupt change in direction at the transition between the second chamber and the third chamber. [0009] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the contaminants removed from the feed stream include one or more of silica, hardness, or heavy metal.

[0010] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the sacrificial electrode is comprised of at least one of Fe, Mg, Al, Zn, or alloys thereof.

[0011] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the inner cylinder is comprised of a conductive material.

[0012] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the at least one sacrificial electrode is cleaned by the fluid stream travelling in the axial direction through the first chamber.

[0013] In another aspect of the apparatus configured for removing contaminants from an influent fluid stream, the flow path winds from a central portion of the apparatus to an outer portion of the apparatus.

[0014] In yet another aspect of the invention, an apparatus configured for removing contaminants from an influent fluid stream comprises: an inlet and an effluent outlet; a flow path through which the fluid stream passes extending from the inlet to the outlet; the flow path is comprised of a first chamber, a second chamber, and a third chamber; the first, second, and third chambers are coaxial; the flow path winds out from a central portion of the apparatus to an outer portion of the apparatus; the first chamber is configured as an electrolysis chamber; and a mixing device disposed in the first chamber of the apparatus for urging the influent fluid stream along the flow path; wherein the first chamber in the flow path is configured to form suspended coagulants and precipitates in the fluid stream, the second chamber in the flow path is configured to grow the suspended coagulants and precipitates in the fluid stream, the third chamber is configured to cause the coagulants and the precipitates to drop out of the fluid stream.

[0015] In yet another aspect of the invention, a method for removing contaminants from an influent fluid stream comprises: providing an apparatus configured for treating an influent fluid stream comprising an inlet and an outlet; providing an influent fluid stream containing contaminants to the inlet; generating and extracting suspended coagulants and precipitates from the fluid stream; extracting the clarified fluid stream from the apparatus.

[0016] In another aspect of the method for removing contaminants from an influent fluid stream, the apparatus is further comprised of: an outer cylinder; a middle cylinder disposed in the outer cylinder; an inner cylinder disposed in the middle cylinder for use as a cathode; the outer, middle, and inner cylinders are concentric and axially oriented; one or more sacrificial electrodes axially oriented in the inner cylinder for use as an anode; a flow path comprised of a first chamber, a second chamber, and a third chamber; the first chamber being defined by the inner diameter of the inner cylinder, the second chamber being defined by the outer diameter of the inner cylinder and the inner diameter of the middle cylinder, the third chamber being defined by the inner diameter of the outer cylinder and the outer diameter of the middle cylinder.

[0017] In another aspect of the method for removing contaminants from an influent fluid stream, the step of generating and extracting suspended coagulants and precipitates from the fluid stream comprises: providing DC power to the sacrificial electrode and the inner cylinder, thereby creating an electrolytic cell in the first chamber; urging the fluid stream through the first chamber of the flow path to form suspended coagulants and precipitates in the fluid stream; urging the fluid stream through the second chamber of the flow path to grow the suspended coagulants and precipitates in the fluid stream; and urging the fluid stream through the third chamber of the flow path, the third chamber causing the coagulants and the precipitates to drop out of the fluid stream.

[0018] In another aspect of the method for removing contaminants from an influent fluid stream, the fluid stream flows in an axial direction through the first, second, and third chambers.

[0019] In another aspect of the method for removing contaminants from an influent fluid stream, the fluid stream flows in a substantially axial direction along the flow path.

[0020] In another aspect of the method for removing contaminants from an influent fluid stream, the flow path has a first abrupt change in direction at the transition between the first chamber and the second chamber, and the flow path has a second abrupt change in direction at the transition between the second chamber and the third chamber.

[0021] In another aspect of the method for removing contaminants from an influent fluid stream, the flow path winds from a central portion of the apparatus to an outer portion of the apparatus.

[0022] In another aspect of the method for removing contaminants from an influent fluid stream, the sacrificial electrode is cleaned by the fluid stream traveling in a substantially axial direction through the first chamber.

[0023] In another aspect of the method for removing contaminants from an influent fluid stream, the apparatus configured for treating an influent fluid stream further comprises a mixing device disposed in the inner cylinder for urging the fluid stream along the flow path; the speed of the mixing device is adjusted to cause the coagulants and the precipitates to drop out of the fluid stream in the third chamber of the flow path.

[0024] In another aspect of the method for removing contaminants from an influent fluid stream, the contaminants include one or more of silica, hardness, or heavy metals.

[0025] In another aspect of the method for removing contaminants from an influent fluid stream, the sacrificial electrode is comprised of one or more of Fe, Al, Mg, Zn, or alloys thereof; wherein the inner cylinder is comprised of a conductive material.

[0026] Advantages of the present invention will become more apparent to those skilled in the art from the following description of the embodiments of the invention which have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and other aspects of the invention will be understood from the description and claims herein, taken together with the drawings showing details of construction and illustrative embodiments, wherein:

[0028] Fig. 1 schematically illustrates one embodiment of an apparatus in accordance with this invention;

[0029] Fig. 2 schematically illustrates another embodiment of an apparatus in accordance with this invention;

[0030] Fig. 3 is a block diagram of another embodiment of an apparatus in accordance with this invention;

[0031] Fig. 4 schematically illustrates the flow of fluid within the apparatus of Fig. 3;

[0032] Fig. 5 is a block diagram of another embodiment of an apparatus in accordance with this invention;

[0033] Fig. 6 schematically illustrates the flow of fluid within the apparatus of Fig. 5;

[0034] Fig. 7a illustrates the efficiency of contaminant removal from the influent of an apparatus constructed in accordance with an embodiment of this invention;

[0035] Fig. 7b illustrates the concentration of contaminants in the clarified effluent of an apparatus constructed in accordance with an embodiment of this invention;

[0036] Fig. 8a illustrates the efficiency of contaminant removal from the influent of an apparatus constructed in accordance with an embodiment of this invention;

[0037] Fig. 8b illustrates the concentration of contaminants in the clarified effluent of an apparatus constructed in accordance with an embodiment of this invention; and

[0038] Fig. 9 illustrates a prior art electrocoagulation device which utilizes an electrode plate bank.

[0039] It should be noted that all the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference numbers are generally used to refer to corresponding or similar features in the different embodiments. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive. DETAILED DESCRIPTION OF THE INVENTION

[0040] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about", is not limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Range limitations may be combined and/or interchanged, and such ranges are identified and include all the sub-ranges stated herein unless context or language indicates otherwise. Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions and the like, used in the specification and the claims, are to be understood as modified in all instances by the term "about".

[0041] "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, or that the subsequently identified material may or may not be present, and that the description includes instances where the event or circumstance occurs or where the material is present, and instances where the event or circumstance does not occur or the material is not present.

[0042] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0043] The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0044] With reference to Fig. 1 , in an illustrated exploded embodiment of the invention, the contaminant removal apparatus 100 is comprised of a concentric outer cylinder 1 15, middle cylinder 1 10, and inner cylinder 105. The outer cylinder 115 having a cylindrical upper portion 1 19 and a frustoconical lower portion 120 that terminates as a discharge outlet 160. At least one effluent outlet 125 and an overflow outlet 155 are located proximate the top of the outer cylinder 1 15.

[0045] The contaminant removal apparatus 100 is further comprised of a removable lid 150 situated on the top of the outer cylinder 1 15. One or more sacrificial electrodes 135 and a mixing device 140 having an axial flow impeller 146 are supported by and extend through the lid 150 into the inner cylinder 105. Mixing device 140 is rotated by motor 145. The axial flow induced by mixing device 140 through inner cylinder 105 prevents fouling from forming on electrodes 135.

[0046] Further, in some embodiments, at least one inlet tube 130 extends through the lid 150. However, in other embodiments, at least one inlet tube 130 is located at bottom of the inner cylinder frustoconical lower portion 120.

[0047] It is contemplated that in some embodiments, the inner cylinder 105 is comprised of a conductive material including, but not limited to, iron or titanium or alloys thereof; the middle cylinder 1 10 is comprised of a flexible material, such as plastic or metal; and the outer cylinder 1 15 is comprised of metal or plastic including, but not limited to, PMMA. Further it is contemplated that the sacrificial electrode is comprised of at least one of Fe, Mg, Al, Zn, or alloys thereof.

[0048] Turning to Fig. 2, in an embodiment of the contaminant removal apparatus 100, inner cylinder 105 is held in place by inner cylinder supports 165 and middle cylinder is held in place by middle cylinder supports 170. Further, the shaft of mixing device 140 is held in position by mixing device support si 75.

[0049] Further, a first chamber 205 is defined by the inner diameter of inner cylinder 105, a second chamber 210 is defined between the outer diameter of inner cylinder 105 and the inner diameter of middle cylinder 1 10, and a third chamber 215 is defined between the inner diameter of the outer cylinder 1 15 and the outer diameter of the middle cylinder 1 10. Additionally, sacrificial electrodes 135 situated in inner cylinder 105 and inner cylinder 105 are connected to DC power supply 305, which creates an electrolytic cell in inner cylinder 105.

[0050] As can be seen, sacrificial electrodes 135 are supported by lid 150. Accordingly, a spent sacrificial electrode 135 can be easily swapped with an unspent sacrificial electrode by lifting the spent sacrificial electrode 135 up out of inner cylinder 105 through lid 150 and replacing the spent sacrificial electrode 135 with an unspent sacrificial electrode 135.

[0051] In practice, when an influent fluid stream containing contaminants, such as one or more of silica, hardness, or heavy metals, is provided to inlet 130 while motor 145 is rotating mixing device 140, the axial force generated by mixing device 140 causes the fluid stream to flow through first chamber 205. In first chamber 205, metal ions, such as Fe, Al, Mg and/or Zn are dissolved from the anodic sacrificial electrode 135 when energized by DC power supply 305.

[0052] One or more of the following reactions take place at sacrificial electrodes 135 when the respective electrode materials are present:

Fe -> Fe²⁺ + 2e^"

Mg -> Mg²⁺ + 2e^"

Al -> Al³⁺ + 3e^"

Zn -> Zn²⁺ + 2e^"

[0053] The following reaction takes place at inner cylinder 105:

2H₂0 + 2e^" -> 20H^" + H₂

[0054] One or more of Fe³⁺, Al³⁺, Mg²⁺, Zn²⁺, and their metal hydroxyl ions and metal hydroxide species such as Fe(OH)₃, Al(OH)₃, Mg(OH)₂, and Zn(OH)₂ are formed in inner cylinder 105 and act as coagulants. The contaminants in the fluid interact with the formed coagulants in the first chamber 205 to form precipitates and coagulates 190. The axial force then carries the fluid stream and precipitates and coagulates 190 from the first chamber 205 to the second chamber 210, where the precipitates and coagulates 190 continue to increase in size. A portion of precipitates and coagulates 190 may fall to the bottom of the outer tube frustoconical lower portion 120 if they cannot be kept suspended in the fluid stream. The axial force moves the fluid stream containing small size precipitates and coagulates 190 from the second chamber 210 to the third chamber 215. In the third chamber 215, the precipitates and coagulates 190 reach a size such that they can no longer remain suspended in the fluid stream and fall to the bottom of frustoconical lower portion 120, meanwhile the clarified fluid exits effluent outlet 125. Overflow exit 155 is provided in the event that effluent outlet 125 becomes obstructed. The precipitates and coagulates 190 are removed from the bottom of frustoconical lower portion 120 through discharge outlet 160.

[0055] In one embodiment of contaminant removal apparatus 100, impeller 146 rotates between about 1 -500 RPM, preferably between about 100-400 RPM, most preferably between about 200-300 RPM. In one embodiment, impeller 146 has between about 2-6 blades, preferably between about 3-5 blades, most preferably about 4 blades. However, it is contemplated that a person having ordinary skill in the art could choose other values.

[0056] In one embodiment of contaminant removal apparatus 100, the ratio of the impeller 146 diameter to the inner diameter of outer cylinder upper section 1 19 is between about 0.2-0.4. Further, the ratio of the inner diameter of middle cylinder 1 10 to the impeller 146 diameter is between about 1.0-2.0. Additionally, the ratio of the clearance between the impeller 146 to the outer cylinder lower frustoconical portion 120, and the inner diameter of outer cylinder upper section diameter 119 is between about 0.2-0.4. Also, between about 1-10mm of clearance is present between mixing device impeller 146 and the inner diameter of inner cylinder 105. However, it is anticipated that a person having ordinary skill in the art could choose different ratios and clearance values.

[0057] In embodiments that use a hydrofoil impeller 146, the clearance between impeller 146 and outer cylinder lower frustoconical section 120 is about equal to the inner diameter of outer cylinder upper section 1 19 divided by 4. In embodiments that use a pitched blade turbine impeller 146, the vertical distance between impeller 146 and outer cylinder lower frustoconical section 120 is about equal to the inner diameter of outer cylinder upper section 1 19 divided by 3. [0058] In another embodiment, the inner diameter of either the inner cylinder 105 or middle

2 2 2

cylinder 1 10 is decided upon. Then, the formula τττ_λ = n(r₂ - r_x ) is used to determine the other of the inner cylinder 105 or middle cylinder 1 10, where ri is the inner radius of inner cylinder 105 and r₂ is the inner radius of middle cylinder 1 10. After determining r and r₂, the inner radius of the outer cylinder upper section 1 19 r₃, is determined by first calculating the settlin velocity of the contaminant particles in the influent feed stream using Stokes Law V_s =

where V_s is the particles' settling velocity in m/s (vertically downwards if p_p > p_f, upwards if p_p < P_f); g is the gravitational acceleration in m/s² (e.g. 9.8 m/s²); p_p is the mass density of the particles in kg/m (e.g. 2.08x10 kg/m for Fe(OH)₃); p_f is the mass density of the fluid in kg/m (e.g. 1000 kg/m for H₂0); and μ is the fluid's dynamic viscosity (in Pa s) (e.g. 1x10^" Pa s for H₂0); and r is the radius of the contaminant particle in μπι (e.g. ΙΟμπι for Fe(OH)₃). Once V_s is calculated, one decides on a flow rate in m³/s within the third chamber 215. The cross-sectional area of the third chamber 215 is then determined by dividing the flow rate in m /s by the particles' settling velocity in m/s. The value for r₃ is calculated by setting the area of the third chamber 215 equal to n(r ² - r₂ ²) . Below in Table 1 are the results of the calculation of r_\, r₂, and r₃ in accordance with the method described above for settling out Fe(OH)³ particles having a radius of ΙΟμηι.

Table 1

V h r₂

(L) h/r₃ (cm) (cm) (cm) (cm)

150 1.4 45.41 32.43 14.09 10.0615 Cross sectional area of first Cross sectional area of second Cross sectional area of third chamber 205 in cm² chamber 210 in cm² chamber 215 in cm² (flow rate = 1 gal/min or (flow rate = 1 gal/min or (flow rate = 1 gal/min or 6.30x10^"5 m³/s) 6.30x10^"5 m³/s) 6.30x10^"5 m³/s)

317.875 305.159 2680.30

[0059] In one exemplary embodiment of contaminant removal apparatus 100, the inner diameter of outer cylinder upper section 1 19 is about 25cm, the diameter of lid 150 is about 35 cm, the inner diameter of middle cylinder 1 10 is about 15 cm, and the inner diameter of inner cylinder 105 is about 10cm. Further, the height of outer cylinder upper section 1 19 is about 52cm, the height of outer cylinder lower frustoconical section 120 (excluding discharge outlet 160) is about 1 1.5cm, the height of middle cylinder 1 10 is about 50cm, and the height of inner cylinder 105 is about 40.2cm. The bottom of middle cylinder 1 10 is located about 2cm above the transition between the outer cylinder upper section 1 19 and outer cylinder lower frustoconical section 120. Further, about 8cm of inner cylinder 105 protrudes from the bottom of middle cylinder 1 10. Further, the maximum flow rate through this embodiment of contaminant removal apparatus 100 is about 0.5 liter/min.

[0060] In another exemplary embodiment of contaminant removal apparatus 100, the inner diameter of outer cylinder upper section 1 19 is about 32 inches, the inner diameter of middle cylinder 1 10 is about 17 inches, and the inner diameter of inner cylinder 105 is about 1 1 inches. The height of outer cylinder upper section 1 19 is about 50 inches. The diameter of the 4 bladed impeller 146 is about 10 inches and it rotates at about 200 RPM. In this embodiment, fluid resides in the inner cylinder 105 and middle cylinder 1 10 for about 50 minutes. The rise rate of fluid inside the third chamber 215 is about .25gpm. Further, the effluent from effluent outlets 125 contains about 5ppm of suspended solids and the waste from discharge outlet 160 contains about 40,000ppm of suspended solids. In some embodiments, some of the liquid exiting from discharge outlet 160 is reintroduced into contaminant removal apparatus 100 as influent through inlets 130.

[0061] Turning to Fig. 3, in an embodiment of the contaminant removal apparatus 100, feed pump 325 provides influent fluid stream to inlets 130 located at the bottom of apparatus 100 from wastewater reservoir 320. It is contemplated that the contents of wastewater reservoir 320 may be comprised of one or more of cooling tower make up water, cooling tower blowdown, industrial waste water, well water, and concentrates from membrane systems. Once inside apparatus 100, contaminants present in the fluid stream interact with metal ions, OH, and metal hydroxyl ions released from by the above mentioned electrochemical reactions that occur at sacrificial electrodes 135 and inner cylinder 105 when energized by DC power supply 305 and form precipitates and coagulants. The precipitates and coagulants are removed from the fluid stream by clarification and collect at the bottom of apparatus 100. The clarified fluid stream exits apparatus 100 through effluent outlets 125 and is directed to effluent tank 310. The precipitates and coagulants are removed from apparatus 100 by blowdown pump 330 through discharge outlet 160 and sent to blowdown tank 335. In the event that effluent outlets 125 become obstructed, clarified fluid stream will exit apparatus 100 via overflow outlet 155 and travel to overflow tank 315.

[0062] Fig. 4 depicts the flowpath of the fluid stream within apparatus 100 of Fig. 3. In this depicted embodiment of apparatus 100, fluid stream delivered through inlets 130 is propelled axially upward from the bottom to the top of the first chamber 205 by mixing device 140 rotating in a clockwise direction. While in first chamber 205, contaminates within the fluid stream precipitate and coagulate and begin to grow. After reaching the top of first chamber 205, the fluid stream changes direction and flows axially from the top of second chamber 210 to the bottom of second chamber 210. While traveling though second chamber 210 the precipitates and coagulates continues to increase in size. Upon exiting the bottom of second chamber 210, the fluid once again changes direction and flows axially from the bottom of the third chamber 215 to the top of the third chamber 215. In the third chamber 215, the precipitates and coagulants reach a size such that they can no longer remain suspended in the fluid stream and fall to the bottom of frustoconical lower portion 120, meanwhile the clarified fluid stream exits effluent outlet 125.

[0063] Turning to Fig. 5, in an embodiment of the contaminant removal apparatus 100, feed pump 325 provides influent fluid stream to inlets 130 located in the lid 150 of apparatus 100 from wastewater reservoir 320. Once inside apparatus 100, contaminants present in the fluid stream interact with metal ions, OH, and metal hydroxyl ions released from by the above mentioned electrochemical reactions that occur at sacrificial electrodes 135 and inner cylinder 105 when energized by DC power supply 305 and form precipitates and coagulants. The precipitates and coagulants are removed from the fluid stream by clarification and collect at the bottom of apparatus 100. The clarified fluid stream exits apparatus 100 through effluent outlets 125 and is directed to effluent tank 310. The precipitates and coagulants are removed from apparatus 100 by blowdown pump 330 through discharge outlet 160 and sent to blowdown tank 335. In the event that effluent outlets 125 become obstructed, clarified fluid stream will exit apparatus 100 via overflow outlet 155 and travel to overflow tank 315.

[0064] In some embodiments of apparatus 100, coagulants and precipitates are continuously removed from apparatus 100 through discharge outlet 160 by blowdown pump 330. However, in other embodiments of apparatus 100, valve 161 is present on discharge outlet 160. Valve 161 remains closed until precipitated solid is accumulated to a predetermined level at the bottom of frustoconical lower portion 120, at which time valve 161 is opened and blowdown pump 330 is activated to remove to the precipitates and coagulants from the bottom of frustoconical lower portion 120. When valve 161 is used to accumulate a predetermined level of precipitated and coagulated solid before removal, this results in very high solid waste being removed from discharge outlet 160, which reduces the volume of waste and recovers more water.

[0065] In some embodiments of apparatus 100 in Figs. 3 and 5, the output of blowdown pump 330 is combined with the output of overflow outlet 155. Further, in embodiments in which apparatus 100 is used in a cooling tower application, cooling tower blowdown can be combined with one or both of the output of blowdown pump 330 and the output of overflow outlet 155. The cooling tower recirculation water can be provided as the influent fluid stream to inlets 130 and the clarified fluid stream exiting effluent outlets 125 can be returned to the cooling tower.

[0066] Fig. 6 depicts the flowpath of the fluid stream within apparatus 100 of Fig. 2. In this depicted embodiment of apparatus 100, fluid stream delivered through inlets 130 is propelled axially downward from the top to the bottom of the first chamber 205 by mixing device 140 rotating in a counter-clockwise direction. While in first chamber 205, contaminates within the fluid stream precipitate and coagulate and begin to grow. After reaching the bottom of first chamber 205, the fluid stream changes direction and flows axially from the bottom of second chamber 210 to the top of second chamber 210. While traveling though second chamber 210 the precipitates and coagulates continue to increase in size. Upon exiting the top of second chamber 210, the fluid stream once again changes direction and flows axially from the top of the third chamber 215 to the bottom of the third chamber 215. In the third chamber 215, the precipitates and coagulants reach a size such that they can no longer remain suspended in the fluid stream and fall to the bottom of frustoconical lower portion 120, meanwhile the clarified fluid exits effluent outlet 125.

[0067] Figs. 7a-8b, depict the laboratory results of a series of tests in which apparatus 100 was used to remove silica, hardness (e.g. Ca), and heavy metals (e.g. Cu) from the influent fluid stream provided to inlets 130. These figures compare the amount of contaminants Ca, Si, and Cu present in the influent feed stream provided to inlets 130 to the amount present in the clarified fluid exiting effluent outlet 125.

[0068] The influent feed stream in Figs. 7a-b was comprised of CaCl₂, NaCl, CuS0₄, and Na₂Si0₃. 480ppm of Ca , 133ppm of Si, and 20ppm of Cu were present in the influent feed stream. Fig. 7a illustrates the percentage of contaminants removed from the influent feed stream by apparatus 100. Fig. 7b illustrates the concentration of Si, Ca, and Cu in the clarified fluid exiting effluent outlet 125. Alkalinity was not present in the influent feed stream of Figs. 7a-b.

[0069] Table 2 below shows the underlying data for Figs. 7a-b. This table shows the amount of Ca, Si, and Cu present in the clarified fluid exiting effluent outlet 125. As can be seen in the table below and Fig. 7a-b, depending upon the current provided by DC power supply 305, apparatus 100 successfully removed between about 58% and 85% of the silica, between about 44% and 90% of the copper, and between about 10% and 17% of the calcium present in the influent feed stream provided to inlets 130. Table 2

[0070] The influent feed stream in Figs. 8a-b was comprised of CaCl₂, NaCl, CuS0₄, Na₂Si0₃, and NaHC0₃. 480ppm of Ca²⁺, 133ppm of Si, and 20ppm of Cu²⁺ were present in the influent feed stream. The influent feed stream was further comprised of alkalinity in the form of 1200ppm as CaC0₃, and 732ppm as HC0₃.

[0071] Fig. 8a illustrates the percentage of contaminants removed from the influent feed stream by apparatus 100. Fig. 8b illustrates the concentration of Si, Ca, and Cu in the clarified fluid exiting effluent outlet 125.

[0072] Table 3 below shows the underlying data for Figs. 8a-b. This table shows the amount of Ca, Si, and Cu present in the clarified fluid exiting effluent outlet 125. As can be seen in the table below and Figs. 8a-b, depending upon the current provided by DC power supply 305, apparatus 100 successfully removed between about 57% and 60% of the silica, between about 36% and 51% of the copper, and between about 36% and 38% of the calcium present in the influent feed stream provided to inlets 130.

Table 3

[0073] As can be seen, when comparing Figs. 7a-b and Table 1 with Figs. 8a-b and Table 2, the removal efficiency of hardness is increased in the presence of alkalinity. However, the removal efficiency of silica and heavy metal increases when a large amount of alkalinity is not present. This is due to the fact that when a large amount of HC0₃ ^' is present in the influent feed water, the following reaction takes place: OH^" + HC0₃ ^" -> C0₃ ^" + H₂0. As can be seen, in the laboratory pilot which used Fe sacrificial electrodes, the HC0₃ ^" consumes some OH^" generated in the electrochemical process, and reduces the coagulation effect of Fe(OH)₃.

[0074] Throughout the gathering of the data contained above in Tables 2 and 3, the fluid between middle cylinder 1 10 and outer cylinder 1 15 was quite clear and free of both large and small particles. Accordingly, the fluid exiting from effluent outlet 125 did not require additional filtration. Traditionally, effluent exiting prior art electrocoagulation units would still contain a significant concentration of contaminants and must be further processed, such as by directing the effluent to a large settling area and/or sand filtration apparatus. Accordingly, apparatus 100 is capable of both precipitating contaminants and separating solids from the fluid stream flowing through apparatus 100 without additional processing equipment. Therefore, since the fluid exiting effluent outlet 125 did not require additional filtration, contaminant removal apparatus 100 eliminates the need for additional processing equipment for the removal of large and small particles, which require additional floor space.

[0075] Another embodiment of this invention is comprised of a method for removing contaminants from an influent fluid stream comprising providing an apparatus 100 configured for treating an influent fluid stream comprising an inlet 130 and an effluent outlet 125, providing an influent fluid stream containing contaminants to the inlet 130, generating and extracting suspended coagulants and precipitates from the fluid stream, and extracting the clarified fluid stream from the apparatus 100 at the effluent outlet 125.

[0076] The apparatus 100 configured for treating an influent fluid stream is further comprised of an outer cylinder 1 15, a middle cylinder 1 10 disposed in the outer cylinder 1 15, and an inner cylinder 105 disposed in the middle cylinder 1 10. The inner cylinder 105 is configured as a cathode. The outer 1 15, middle 1 10, and inner 105 cylinders are concentric and axially oriented. One or more sacrificial electrodes 135 are axially oriented in the inner cylinder 105 for use as anodes.

[0077] The apparatus 100 is further comprised of a flow path. The flow path is comprised of a first chamber 205, a second chamber 210, and a third chamber 215. The first chamber 205 is defined by the inner diameter of the inner cylinder 105, the second chamber 210 is defined between the outer diameter of the inner cylinder 105 and the inner diameter of the middle cylinder 1 10, the third chamber 215 is defined between the inner diameter of the outer cylinder 1 15 and the outer diameter of the middle cylinder 110.

[0078] The step of generating and extracting suspended coagulants and precipitates from the fluid stream comprises providing DC power to the sacrificial electrode 135 and the inner cylinder 105, thereby creating an electrolytic cell in the first chamber 205; urging the fluid stream through the first chamber 205 of the flow path to form suspended coagulants and precipitates in the fluid stream; urging the fluid stream through the second chamber 210 of the flow path to grow the suspended coagulants and precipitates in the fluid stream; and urging the fluid stream through the third chamber 215 of the flow path, the third chamber 215 causing the coagulants and the precipitates to drop out of the fluid stream into the frustoconical lower portion 120 of outer cylinder 1 15. The coagulants and precipitates drop out of the fluid stream in third chamber 215 due to slow flow velocity of the fluid stream through the third chamber 215 and the increased size of the coagulants and precipitates. [0079] Further, since the fluid stream flows in an axial direction through the first 205, second 210, and third 215 chambers, the one or more sacrificial electrodes are cleaned by the fluid stream travelling in the axial direction through the first chamber 205.

[0080] As can be seen particularly in Figs 4 and 6, the fluid stream flows in a substantially axial direction along the flow path. However, the fluid stream does have a first abrupt change in direction at the transition between the first chamber 205 and the second chamber 210, and a second abrupt change in direction at the transition between the second chamber 210 and the third chamber 215. Additionally, the flow path folds back upon itself after the first and second abrupt changes in direction. Further, the flow path winds axially from a central portion of the apparatus 100 to an outer portion of the apparatus 100.

[0081] In some embodiments of apparatus 100 the speed of the mixing device 140 disposed in the inner cylinder 105 for urging the fluid stream along the flow path is adjusted to obtain a flow velocity in the third chamber 215 which is conducive to allowing the precipitates and coagulants to drop from the fluid stream.

[0082] While this invention has been described in conjunction with the specific embodiments described above, it is evident that many alternatives, combinations, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of this invention, as set forth above are intended to be illustrative only, and not in a limiting sense. Various changes can be made without departing from the spirit and scope of this invention. Therefore, the technical scope of the present invention encompasses not only those embodiments described above, but also all that fall within the scope of the appended claims.

[0083] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated processes. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. These other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language the claims.

[0084] What is claimed is:

Claims

1. An apparatus configured for removing contaminants from an influent fluid stream comprising:

an inlet and an effluent outlet;

an outer cylinder having a cylindrical top section and a frustoconical lower section;

a middle cylinder disposed in said outer cylinder;

an inner cylinder disposed in said middle cylinder, said inner cylinder is configured as a cathode;

said outer, middle, and inner cylinders being concentric and coaxial;

a flow path through which said fluid stream passes extending from said inlet to said outlet; said flow path is comprised of a first chamber, a second chamber, and a third chamber;

said first chamber being defined by the inner diameter of said inner cylinder, said second chamber being defined by the outer diameter of said inner cylinder and the inner diameter of said middle cylinder, said third chamber being defined by the inner diameter of said outer cylinder and the outer diameter of said middle cylinder;

at least one sacrificial electrode axially oriented in said inner cylinder for use as an anode; a DC power supply configured to provide electric potential to said inner cylinder and said at least one sacrificial electrode, thereby creating an electrolysis chamber in said first chamber; and

a mixing device disposed in the inner cylinder of said apparatus for urging said influent fluid stream along said flow path.

2. The apparatus of claim 1, wherein said first chamber in said flow path is configured to form suspended coagulants and precipitates in said fluid stream, said second chamber in said flow path is configured to grow said suspended coagulants and precipitates in said fluid stream, said third chamber is configured to cause said coagulants and said precipitates to drop out of said fluid stream.

3. The apparatus of claim 2, wherein said flow path has a first abrupt change in direction at the transition between said first chamber and said second chamber, said flow path has a second abrupt change in direction at the transition between said second chamber and said third chamber.

4. The apparatus of claim 3, wherein said contaminants removed from said feed stream include one or more of silica, hardness, or heavy metal.

5. The appratus of claim 4, wherein said sacrificial electrode is comprised of at least one of Fe, Mg, Al, Zn, or alloys thereof.

6. The apparatus of claim 5, wherein said inner cylinder is comprised of a

conductive material.

7. The apparatus of claim 6, wherein said at least one sacrificial electrode is cleaned by said fluid stream travelling in said axial direction through said first chamber.

8. The apparatus of claim 7, wherein said flow path winds from a central portion of said apparatus to an outer portion of said apparatus.

9. An apparatus configured for removing contaminants from an influent fluid stream comprising:

an inlet and an effluent outlet

a flow path through which said fluid stream passes extending from said inlet to said outlet; said flow path is comprised of a first chamber, a second chamber, and a third chamber; said first, second, and third chambers are coaxial; said flow path winds out from a central portion of said apparatus to an outer portion of said apparatus;

said first chamber is configured as an electrolysis chamber; and

a mixing device disposed in the first chamber of said apparatus for urging said influent fluid stream along said flow path;

wherein said first chamber in said flow path is configured to form suspended coagulants and precipitates in said fluid stream, said second chamber in said flow path is configured to grow said suspended coagulants and precipitates in said fluid stream, said third chamber is configured to cause said coagulants and said precipitates to drop out of said fluid stream.

10. A method for removing contaminants from an influent fluid stream comprising: providing an apparatus configured for treating an influent fluid stream comprising an inlet and an outlet;

providing an influent fluid stream containing contaminants to said inlet;

generating and extracting suspended coagulants and precipitates from said fluid stream; extracting said clarified fluid stream from said apparatus.

1 1. Said apparatus configured for treating an influent fluid stream of claim 10 further comprising:

an outer cylinder;

a middle cylinder disposed in said outer cylinder;

an inner cylinder disposed in said middle cylinder for use as a cathode;

said outer, middle, and inner cylinders are concentric and axially oriented;

one or more sacrificial electrodes axially oriented in said inner cylinder for use as an anode;

a flow path comprised of a first chamber, a second chamber, and a third chamber;

said first chamber being defined by the inner diameter of said inner cylinder, said second chamber being defined by the outer diameter of said inner cylinder and the inner diameter of said middle cylinder, said third chamber being defined by the inner diameter of said outer cylinder and the outer diameter of said middle cylinder.

12. The method of claim 1 1, in which the step of generating and extracting suspended coagulants and precipitates from said fluid stream comprises:

providing DC power to said sacrificial electrode and said inner cylinder, thereby creating an electrolytic cell in said first chamber;

urging said fluid stream through said first chamber of said flow path to form suspended coagulants and precipitates in said fluid stream; urging said fluid stream through said second chamber of said flow path to grow said suspended coagulants and precipitates in said fluid stream; and

urging said fluid stream through said third chamber of said flow path, said third chamber causing said coagulants and said precipitates to drop out of said fluid stream.

13. The method of claim 12, wherein said fluid stream flows in an axial direction through said first, second, and third chambers.

14. The method of claim 13, wherein said fluid stream flows in a substantially axial direction along said flow path.

15. The method of claim 14, wherein said flow path has a first abrupt change in direction at the transition between said first chamber and said second chamber, and said flow path has a second abrupt change in direction at the transition between said second chamber and said third chamber.

16. The method of claim 15, wherein said flow path winds from a central portion of said apparatus to an outer portion of said apparatus.

17. The method of claim 16, wherein said sacrificial electrode is cleaned by said fluid stream traveling in a substantially axial direction through said first chamber.

18. Said apparatus configured for treating an influent fluid stream of claim 17 further comprising a mixing device disposed in said inner cylinder for urging said fluid stream along said flow path; the speed of said mixing device is adjusted to cause said coagulants and said precipitates to drop out of said fluid stream in said third chamber of said flow path.

19. The method of claim 10, wherein said contaminants include one or more of silica, hardness, or heavy metals.

20. The method of claim 1 1 , wherein said sacrificial electrode is comprised of one or more of Fe, Al, Mg, Zn, or alloys thereof; wherein said inner cylinder is comprised of a conductive material.