Methods and apparatus for separation of solids from liquids by dissolved gas floatation

Abstract

The present invention relates to methods and apparatus for separation of solids from liquids and separation of liquids from liquids (such as oil from water) by dissolved gas floatation. A dissolved gas floatation clarifier is described as is a liquid-gas mixer, a liquid-liquid mixer, and solid-liquid chemical feeders. The methods and apparatus of the present invention are particularly suitable for supplying dissolved air and mixing of chemicals for use in separation of solids in dissolved air floatation clarifiers.

Description

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to methods and apparatus for separation of iquids and separation of liquids from liquids (such as oil from water) by s floatation. The methods and apparatus of the present invention are uitable for supplying dissolved air and mixing of chemicals for use in solids in dissolved air floatation clarifiers.

[0004] 2. Description of Related Art

[0005] The methods and apparatus for mixing fluids and dissolving gases in sed in co-pending patent application Ser. No. 09/879,496, filed Jun. 12, name of Johnny Arnaud and assigned to the same assignee as the present here liquids can be totally saturated with dissolved gases at any pressure, the opportunity for improvements in the methods and apparatus for both solids and trace organic fluids suspended in a second fluid, such as solved gas floatation.

[0006] Saturating a liquid such as water with a dissolved gas under pressure then saturated liquid into other water contaminated with suspended solids or suspended liquids, such as oil, and releasing the pressure allows the gas to come out of solution as microscopic (small) bubbles that rise slowly in the liquid. As the bubbles form they attach themselves to the contaminating suspended solid particles and liquid droplets increasing the buoyancy and accelerating the rise of the particles and droplets to the surface where they can be removed. The process can be used for separating solids and trace organic contaminants from fluids in dissolve air floatation clarifiers. While that exemplary application is described in the present invention, it is understood that there are many other implementations without deviating from the intent and spirit of the present invention.

[0007] The basic requirements of a system used for gas floatation of both solids and liquids have been well defined to include introduction of finely dispersed gas bubbles into the stream to be treated, a floatation zone of minimum turbulence, and a means of removing the floated material. The microscopic bubbles are obtained by either a recycle pressure system where a portion of the clarified water is recycled through a dissolved gas generator and then mixing the saturated water with the incoming wastewater stream as it enters the clarifier, or by a full-stream pressure system where the entire incoming wastewater stream flows through a dissolved gas generator ahead of the clarifier. In addition, chemicals to aid in separation of the contaminants from the water are commonly introduced into the stream and have become part of the basic requirements of gas floatation systems. The selection of systems and methods for treating specific wastewater streams depends on what contaminants are present, whether the contaminants are predominantly suspended solids with a small amount of liquid contaminants or predominantly liquids with a small amount of suspended solids, and what is to be done with the contaminants removed from the treated water.

[0008] In treating water for removal of contaminants, various chemicals perform selected functions in the treating process. The use of chemicals in wastewater treatment is discussed in U.S. Pat. No. 6,254,267, dated Jul. 3, 2001, in the name of Johnny Arnaud and assigned to the same assignee as the present application, incorporated by reference herein in its entirety. The discussions in that referenced patent on use of chemicals in wastewater treatment are repeated for clarity. The chemicals can be liquids or solids in granular or powder form. Some solids are dissolved into and used as liquids in the treating process. Other chemicals may perform their treating functions as solids.

[0009] Many solid-liquid separation processes in wastewater treatment employ coagulation and flocculation. Laymen have long used the terms “coagulation” and “flocculation” interchangeably in discussing solid-liquid separation processes. Colloid scientists, however, have adopted a more specific usage. “Coagulation” implies aggregation caused by compression of the electrical double layers surrounding colloidal particles. “Flocculation” is restricted to cases where polymer bridging or some similar mechanism operates. Coagulation and flocculation are essential in many solid-liquid separation processes, since many suspended particles are too small for gravitational settling alone to effectively remove the particles. Coagulants can be purchased in both the liquid and solid phases. Polymers used as flocculating agents can also be obtained in liquid and solid phases. In liquid phase, those chemicals must be mixed and dispersed to react with the contaminants throughout the water. In powdered or granulated solid form, those chemicals must be dissolved first and then mixed with water in order to react with the contaminants.

[0010] Chemicals that remain powdered during the treating process may also be used in addition to coagulants and flocculants to remove contaminants from water. Bentonite clays and activated carbon powders exemplify such solid chemicals used to remove organic and dissolved metal contaminants from water. The powders must be wetted, fed into the water, and dispersed in order to reach the contaminants throughout the body of water to be treated. Once injected into the water, the powders may also have to be coagulated and flocculated so they can be separated by floatation or settling to remove them from the water.

[0011] Most of the deficiencies of the present dissolved gas floatation systems are in the quality of the bubbles produced, size and cost of the apparatus used to generate the bubbles, method of introducing the bubbles into the stream of water to be treated, and the success of mixing and dispersing the chemicals added by the existing apparatus used.

[0012] The dynamics of fluid flow generally can be expressed by conservation of energy, momentum, and impulse.

SUMMARY OF THE INVENTION

[0013] The present invention provides a new method and apparatus for mixing solid chemicals and dissolving the gas used to create the microscopic bubbles for separation of suspended solids and organic contaminants from water by dissolved gas floatation.

[0014] An apparatus in accordance with the present invention may employ a floatation clarifier, a liquid-gas mixer as a dissolved gas generator to supply ic bubbles for floatation, liquid-liquid mixers to disperse the chemicals n separation of the contaminants from the water, and solid-liquid chemical and dissolve the bulk powdered chemicals used in the separation process.

[0015] One embodiment of the present invention may employ a dissolved gas ifier with an inlet to provide the retention time to allow chemical separation act and microscopic bubbles to form, a floatation zone of minimum th a rake to remove the floating contaminant sludge, a storage compartment separated sludge is deposited, a water outlet to remove the clarified water fering with floatation, a settling zone for heavy solid sludge that will not e pump for transferring the sludge out of the system, a recycle pressure em that returns the recycled water to an inlet manifold with a fluid mixer dissolved gas generator to produce the microscopic bubbles, a liquid-liquid erse the flocculating chemical in the incoming wastewater stream before it arifier, a liquid-liquid mixer to disperse the coagulating chemical in the tewater stream ahead of the flocculating chemical, and two chemical feed ject the coagulating and flocculating chemicals into the liquid-liquid mixers.

[0016] A second embodiment of the present invention may employ a dissolved system as described above, a recycle pressure aeration system with a fluid as to produce the microscopic bubbles that returns the recycled water and the incoming wastewater stream with a third liquid-liquid mixer ahead of an inlet manifold , two liquid-liquid mixers to disperse the coagulating and flocculating he incoming contaminated water.

[0017] A third embodiment of the present invention may employ a dissolved gas ifier as described above, a full-stream pressure aeration system with a fluid as a dissolved gas generator in the incoming wastewater stream ahead of occulating agent is introduced to produce the microscopic bubbles, two mixers to disperse the coagulating and flocculating chemicals in the taminated water.

[0018] A fourth embodiment of the present invention may employ a dissolved gas ifier as described above, a recycle pressure aeration system that returns the er to an inlet manifold with a fluid mixer applied as a dissolved gas produce the microscopic bubbles, two liquid-liquid mixers to disperse the nd flocculating chemicals in the incoming contaminated water, two liquid-liquid to disperse wetted solid Bentonite and activated carbon powders in the ntaminated wastewater stream ahead of where the coagulating and hemicals are introduced, and four chemical feed systems for mixing bulk micals into water and injecting them into the liquid-liquid mixers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 depicts a schematic representation of a dissolved gas floatation em employing radial-grooved mixers to feed liquid chemicals into the stream ted water and to dissolve the air used for separation of contaminants by h a recycle pressure system used for aeration.

[0020] FIG. 2 depicts a schematic representation of a dissolved gas floatation m employing radial-grooved mixers to feed both liquid and solid chemicals am of contaminated water and to dissolve the air used for separation of by floatation with a recycle pressure system used for aeration. The system a chemical feed system for dissolving and wetting powdered bulk chemicals g the contaminated water.

[0021] FIG. 3 depicts a schematic representation of a dissolved gas floatation m employing radial-grooved mixers to feed both liquid and solid chemicals am of contaminated water and to dissolve the air used for separation of by floatation with a full-stream pressure system used for aeration. The mploys a chemical feed system for dissolving and wetting powdered bulk d in treating the contaminated water.

[0022] FIG. 4 depicts in schematic representation of another embodiment of a floatation clarifier system 70 in which all solid chemicals are used in the astewater.

[0023] FIGS. 5A and 5B depict a fluid mixer in accordance with the present G 5A illustrates the horizontal flow of the fluid as it enters the mixer. FIG a vertical cutaway view of the mixer identifying major components and low of the fluids as they are being mixed.

[0024] FIGS. 6-10 are schematic representations of a powder chemical wetting ystem in accordance with the present invention. FIG. 6 depicts the chemical powder mixing and feeding system and identifies basic system components. FIGS. 6-11 mical mixing and feeding system in various stages of operation.

[0025] FIG. 11 depict the distributor positioned in the mixing tank of the powder ing and feeding system.

[0026] FIGS. 12A and 12B provide an illustration of a distributor of one of the present invention.

[0027] FIGS. 13A and 13B provide three-dimensional illustrations of a typical d ring and a venturi-orifice ring.

[0028] FIG. 14 shows a vertical cross-sectional view of a fluid mixer assembly of nt of the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0029] Illustrative embodiments of the invention are described below as they loyed in the use of the methods and apparatus for separating solids and fluids form other fluids, such as water or saltwater. In the interest of clarity, es or an actual implementation are described in this specification. It will of reciated that in the development of any such actual embodiment, numerous n-specific decisions must be made to achieve the developers' specific s compliance with system-related and business-related constraints, which m one implementation to another. Moreover, it will be appreciated that such t effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this

[0030] Further aspects and advantages of the various embodiments of the l become apparent from consideration of the following description and

[0031] Referring now to the drawings in more detail, and particular to FIG. 1, icted in schematic representation a dissolved gas flotation clarifier system 1 recycled pressure aeration system for separating suspended solids and trace s from an aqueous fluid, such as water or wastewater, by floatation in ith the present invention. The dissolved gas floatation clarifier system 1 water inlet 10 for the contaminated fluid to be clarified, a fluid mixer 11 for of coagulation agents with a chemical feed pump 8 and chemical supply a second fluid mixer 15 for introduction of flocculating agents with a pump 4 and chemical supply 2, a dissolved gas floatation (DGF) clarifier ycle pressure aeration system with a recycling pump 43 and a fluid mixer issolved gas generator 45.

[0032] The dissolved gas clarifier 19 consist an inlet manifold 14, a retention where the microscopic bubbles form and become attached to the a floatation cell 41 to allow the contaminants to float with minimum rake assembly 21 with a series of rakes 22 and a variable speed drive 25 to ting contaminants off the top of the water, a sludge collection chamber 29, a passageway 30 for the clarified water to exit the floatation cell 41, an outlet collection chamber 26, and a sludge pump 35 to remove the accumulated sludge 31 and 40.

[0033] The recycle pressure aeration system consists of a pump 43 to furnish the recycled water at the pressure required to dissolve the amount of gas needed for system operation, a fluid mixer applied as a dissolved gas generator 45 with a built in venturi to draw in the atmospheric air for dissolving into the water, and associated piping.

[0034] Wastewater (or water) containing suspended solids enters the dissolved gas floatation clarifier system 1 through the water inlet 10 under pressure and flows into the fluid mixer 11. A coagulating agent is drawn from container 6 by chemical feed pump 8 through piping 7 and injected into the fluid mixer 11 through piping 9 and thoroughly mixed with the incoming wastewater stream. The wastewater flows out of fluid mixer 11 through piping 12 and into fluid mixer 15. A flocculating agent is drawn from container 2 by chemical feed pump 4 through piping 3 and injected into fluid mixer 15 through piping 5 and thoroughly mixed with the incoming wastewater stream. The wastewater flows out of the fluid mixer 15 through piping 13 and into a manifold 14 where it is mixed with recycled clarified water saturated with dissolved air. The recycling pump 43 draws clarified water through shutoff valve 28 and piping 42, increases its pressure, and pumps the recycled water into a fluid mixer applied as a dissolved gas generator 45 where the water is saturated with air drawn from the atmosphere. The saturated recycled water flows out the dissolved gas generator 45 through piping 46 and into the manifold 14 where it is mixed with the incoming wastewater from piping 13. The mixture of water 16 is released in a retention chamber 18 where the air comes out of solution to form microscopic bubbles 17.

[0035] The time in the retention chamber 18 allows the coagulating and flocculating chemicals to form larger suspended solid particles with microscopic bubbles attached that causes them to float. The wastewater flows upward in the retention chamber 18 and over a weir 20 into the floatation cell 41. A rake assembly 21 skims the surface of the water with a series of individual racks 22 and carries the solids up an incline 23 and allows them to spill over 24 into a sludge collection chamber 29 separating the floating suspended solids from the water.

[0036] The rake assembly 21 is driven by a variable speed drive 25. A small percentage of the suspended solids 40 settle to the bottom of the floatation cell 41. The clarified water flows downward in the floatation cell 41 and up a passageway 30 and spills over into an outlet collection chamber 26. Some of the clarified water is recycled through shutoff valve 28 and saturated to supply the air bubbles for floatation as previously described. The remainder of the clarified water is discharged from the dissolved gas floatation clarifier system 1 through the outlet 27. The sludge 31 in the sludge collection chamber 29 and the sludge 40 settled in the bottom of the floatation cell 41 are periodically removed. The sludge is removed from the sludge chamber 29 by turning the sludge pump 35 on and opening the selection valve 36. The sludge 31 is drawn by the sludge pump 35 through the sludge outlet 32 and piping 34 when selection valve 36 is opened and discharged from the system through pump outlet 33. The sludge 40 settled on the bottom of the floatation cell 41 is drawn by the sludge pump 35 through the sludge outlet port 39 and piping 38 when selection valve 37 is opened and is discharged from the system through pump outlet 33.

[0037] FIG. 2 depicts in schematic representation a second embodiment of a flotation clarifier system 50 employing another recycle pressure aeration parating suspended solids and trace organic fluids in accordance with the tion. The dissolved gas floatation clarifier system 50 consists of a water the contaminated wastewater to be clarified, an inline fluid mixer 11 for of coagulation agents with a chemical feed pump 8 and chemical supply a second inline fluid mixer 54 for introduction of dissolved air from the ssure aeration system for flotation, a third inline fluid mixer 15 for f flocculating agents with a chemical feed pump 4 and chemical supply 2, a floatation (DGF) clarifier 19, and a recycle pressure aeration system with a p 43 and a fluid mixer applied as a dissolved gas generator 55 connected to line fluid mixer 54.

[0038] The dissolved gas clarifier 19 consist an inlet manifold 14, a retention where the microscopic bubbles form and become attached to the a floatation cell 41 to allow the contaminants to float with minimum rake assembly 21 with a series of rakes 22 and a variable speed drive 25 to ting contaminants off the top of the water, a sludge collection chamber 29, a 0 for the clarified water to exit the floatation cell 41, an outlet collection nd move the accumulated sludge 31 and 40.

[0039] The recycle pressure aeration system consists of a pump 43 to furnish the r at the pressure required to dissolve the amount of gas needed for system luid mixer applied as a dissolved gas generator 55 with a built in venturi to mospheric air for dissolving into the water, and associated piping.

[0040] Wastewater (or water) containing suspended solids enters the dissolved larifier system 50 through the water inlet 10 under pressure and flows into fluid mixer 11. A coagulating agent is drawn from container 6 by chemical through piping 7 and injected into the fluid mixer 11 through piping 9 and xed with the wastewater stream. The wastewater flows out of fluid mixer ne 53 and into the second inline fluid mixer 54 where the dissolved air used s introduced.

[0041] Clarified water is drawn through shutoff valve 28 and line 42 by the ssure pump 43 and pumped through lines 51 and 52 into the fluid mixer dissolved gas generator 55 and saturated with air drawn from the he recycled water saturated with air flows out the bottom of the dissolved 55 and into inline fluid mixer 54 where it is mixed with the incoming he wastewater with the dissolved air flows out of fluid mixer 54 through nto the fluid mixer 15. A flocculating agent is drawn from container 2 by pump 4 through piping 3 and injected into fluid mixer 15 through piping 5 y mixed with the incoming wastewater stream. The wastewater flows out of r 15 through piping 13 and into a manifold 14. The wastewater flows out of er 15 through piping 13 and into the manifold 14 where the mixture of ssolve air, and wastewater 16 is released in a retention chamber 18 where out of solution to form microscopic bubbles 17.

[0042] The time in the retention chamber 18 allows the coagulating and hemicals to form larger suspended solid particles with microscopic bubbles causes them to float. The water flows upward in the retention chamber 18 and over a weir 20 into the floatation cell 41. A rake assembly 21 skims the surface of the series of individual racks 22 and carries the solids up an incline 23 and to spill over 24 into a sludge collection chamber 29 separating the floating ids from the water.

[0043] The rake assembly 21 is driven by a variable speed drive 25. A small the suspended solids 40 settle to the bottom of the floatation cell 41. The r flows downward in the floatation cell 41 and up a passageway 30 and to an outlet collection chamber 26. Some of the clarified water is recycled off valve 28 and saturated to supply the air bubbles for floatation as scribed. The remainder of the clarified water is discharged from the floatation clarifier system 1 through the outlet 27. The sludge 31 in the tion chamber 29 and the sludge 40 settled in the bottom of the floatation cell ically removed. The sludge is removed from the sludge chamber 29 by udge pump 35 on and opening the selection valve 36.

[0044] The sludge 31 is drawn by the sludge pump 35 through the sludge outlet g 34 when selection valve 36 is opened and discharged from the system outlet 33. The sludge 40 settled on the bottom of the floatation cell 41 is sludge pump 35 through the sludge outlet port 39 and piping 38 when e 37 is opened and is discharged from the system through pump outlet 33.

[0045] FIG. 3 depicts in schematic representation a third embodiment of a clarifier system 60 employing a full stream pressure aeration system for spended solids and trace organic fluids in accordance with the present invention. The dissolved gas floatation clarifier system 60 consists of a water inlet 10 for ted wastewater to be clarified, an inline fluid mixer 11 for introduction of gents with a chemical feed pump 8 and chemical supply container 6, a fluid mixer applied as a dissolved gas generator 62 for introduction of in the full incoming wastewater stream for flotation, a third inline fluid introduction of flocculating agents with a chemical feed pump 4 and ly 2, and a dissolved gas floatation (DGF) clarifier 19.

[0046] The dissolved gas clarifier 19 consist an inlet manifold 14, a retention where the microscopic bubbles form and become attached to the a floatation cell 41 to allow the contaminants to float with minimum rake assembly 21 with a series of rakes 22 and a variable speed drive 25 to ting contaminants off the top of the water, a sludge collection chamber 29, a 0 for the clarified water to exit the floatation cell 41, an outlet collection nd a sludge pump 35 to remove the accumulated sludge 31 and 40.

[0047] Wastewater containing suspended solids enters the dissolved gas floating em 60 through the water inlet 10 under pressure and flows into the first inline 1. A coagulating agent is drawn from container 6 by chemical feed pump 8 g 7 and injected into the fluid mixer 11 through piping 9 and thoroughly e wastewater stream.

[0048] The wastewater flows out of fluid mixer 11 through line 61 and into fluid mixer applied as a dissolved gas generator 62 where the dissolved air tion is introduced. The wastewater with the dissolved air flows out of fluid mixer 62 through line 63 and into the fluid mixer 15. A flocculating agent is drawn from y chemical feed pump 4 through piping 3 and injected into fluid mixer 15 g 5 and thoroughly mixed with the wastewater stream.

[0049] The wastewater flows out of the fluid mixer 15 through piping 13 and into 14 where the mixture of chemicals, dissolve air, and water 16 is released in amber 18 where the air comes' out of solution to form microscopic bubbles in the retention chamber 18 allows the coagulating and flocculating form larger suspended solid particles with microscopic bubbles attached that o float.

[0050] The water flows upward in the retention chamber 18 and over a weir 20 tion cell 41. A rake assembly 21 skims the surface of the water with a series racks 22 and carries the solids up an incline 23 and allows them to spill over ge collection chamber 29 separating the floating suspended solids from the ke assembly 21 is driven by a variable speed drive 25. A small percentage of solids 40 settle to the bottom of the floatation cell 41. The clarified water rd in the floatation cell 41 and up a passageway 30 and spills over into an ion chamber 26. The clarified water is discharged from the dissolved gas ifier system 1 through the outlet 27.

[0051] The sludge 31 in the sludge collection chamber 29 and the sludge 40 bottom of the floatation cell 41 are periodically removed. The sludge is m the sludge chamber 29 by turning the sludge pump 35 on and opening the ve 36. The sludge 31 is drawn by the sludge pump 35 through the sludge outlet 32 and piping 34 when selection valve 36 is opened and discharged from the system through pump outlet 33. The sludge 40 settled on the bottom of the floatation cell 41 is drawn by the sludge pump 35 through the sludge outlet port 39 and piping 38 when selection valve 37 is opened and is discharged from the system through pump outlet 33.

[0052] When a large amount of coagulating and flocculating agents are to be used, costs can be greatly reduced by purchasing the chemicals in the solid phases and dissolving them in water for feeding into the wastewater stream. In addition, when trace organic and dissolved metals are also to be removed, solid chemical powders that do not dissolve and remain as solids, such as Bentonite clays and activated carbon, may be used to remove the contaminants by feeding them into the wastewater stream ahead of the dissolved gas floatation clarifier. The chemical powders must be wetted and dispersed in water before being fed into the wastewater stream.

[0053] FIG. 4 depicts in schematic representation of another embodiment of a dissolved gas floatation clarifier system 70 in which all solid chemicals are used in the treatment of wastewater. The dissolved gas floatation clarifier system 70 consists of a water inlet 79 for contaminated wastewater treatment, a fluid mixer 80 for introduction of Bentonite with a feed pump 76 and a powder wetting and mixing system 77, a second fluid mixer 82 for introduction of activated carbon with a feed pump 73 and a powder wetting and mixing system 75, a third fluid mixer 11 for introduction of a coagulating agent with a feed pump 8 and a coagulating agent dissolving and mixing system 72, a fourth fluid mixer 15 for introduction of a flocculating agent with a feed pump 4 and a flocculating agent dissolving and mixing system 71, a dissolved air floatation clarifier 19, and a recycle pressure aeration system with a recycling pump 43 and a fluid mixer applied as a dissolved gas generator 45. The dissolved gas floatation clarifier 19 and the re aeration system are as described in the discussions of FIG. 1.

[0054] Wastewater containing suspended solids enters the dissolved gas floatation em 47 under pressure and flows into the fluid mixer 80. The Bentonite clay ater is drawn by the feed pump 76 from the Bentonite wetting and mixing d pumped through piping 78 into fluid mixer 80 and thoroughly mixed with wastewater stream.

[0055] The wastewater flows out of fluid mixer 80 through piping 81 and into 2. The activated carbon dispersed in water is drawn by feed pump 73 from carbon wetting and mixing system 75 and pumped through piping 74 into 2 and thoroughly mixed with the wastewater stream. The wastewater flows ixer 82 through piping 83 and into fluid mixer 11. A coagulating agent is the dissolving and mixing system 72 by chemical feed pump 8 through injected into the fluid mixer II through piping 9 and thoroughly mixed with r stream.

[0056] The wastewater flows out of fluid mixer 11 through piping 12 and into 5. A flocculating agent is drawn from the dissolving and mixing system 71 feed pump 4 through piping 3 and injected into fluid mixer 15 through thoroughly mixed with the wastewater stream. As described in the preceding e wastewater flows out of the fluid mixer 15 through piping 13 and into a where it is mixed with recycled clarified water saturated with dissolved air. g pump 43 through shutoff valve 28 and piping 42 draws clarified water, increases its pressure, and pumps the cycled water into a fluid mixer applied as a dissolved gas generator 45 where the water is saturated with air drawn from the atmosphere.

[0057] The saturated recycled water flows out the dissolved gas generator 45 through piping 46 and into the manifold 14 where it is mixed with the incoming wastewater from piping 13. The mixture of water 16 is released in a retention chamber 18 where the air comes out of solution to form microscopic bubbles 17. The time in the retention chamber 18 allows the coagulating and flocculating chemicals to form larger suspended solid particles with microscopic bubbles attached that causes them to float. The water flows upward in the retention chamber 18 and over a weir 20 into the floatation cell 41.

[0058] A rake assembly 21 skims the surface of the water with a series of rakes 22 and carries the solids up an incline 23 and allows them to spill over 24 into a sludge collection chamber 29 separating the floating suspended solids from the water. The rake 21 is driven by a variable speed drive 25. A small percentage of the suspended solids 40 settle to the bottom of the floatation cell 41. The clarified water flows downward in the floatation cell 41 and up a passage 30 and spills over into an outlet collection chamber 26. Some of the clarified water is recycled through shutoff valve 28 and saturated to supply the air bubbles for floatation as previously described. The remainder of the clarified water is discharged from the dissolved gas floatation clarifier system 47 through the outlet 27.

[0059] The sludge 31 in the sludge collection chamber 29 and the sludge 40 bottom of the floatation cell 41 are periodically removed. The sludge is the sludge chamber 29 by turning the sludge pump 35 on and opening the e 36. The sludge 31 is drawn by the sludge pump 35 through the sludge piping 34 when selection valve 36 is opened and discharged from the h pump outlet 33. The sludge 40 settled on the bottom of the floatation cell y the sludge pump 35 through the sludge outlet port 39 and piping 38 when e 37 is opened and is discharged from the system through pump outlet 33.

[0060] The fluid mixers 11, 15, 45, 55, 62, 80, and 82 used as liquid-to-liquid ssolved gas generators may correspond structurally and functionally to the d ring mixer disclosed in co-pending patent application Ser. No. iled Jun. 12, 2001, in the name of Johnny Arnaud and assigned to the same he present application. The fluid mixers applied as liquid-to-liquid mixers ved gas generators are shown in FIGS. 1-4. While the radial-grooved ring scribed herein, the foregoing co-pending application is hereby incorporated rence and can be referred to for further structural detail.

[0061] FIGS. 5A and 5B illustrate the mixer 11, 15, 80, or 82 in FIGS. 1-4. FIG. 5A zontal cross-sectional view of the liquid inlet to the mixer 11, 15, 80, or 82 e radial-groove ring 85, the distribution channel 86, the eight radial grooves on of the orifices 88 over the radial grooves 87, and an impact zone 89 to grooves 87 are directed. FIG. 5B provides a vertical cross-sectional view of er 11, 15, 80, or 82 assembly consisting of top inlet housing 91, an orifice plate 93 with orifices 92, a radial-grooved ring 85, and an impact zone 89. The arrows indicate the direction of fluid flow.

[0062] The wastewater enters the fluid mixer 11, 15, 80, or 82 through the side inlet 84, flows around the distribution channel 86, and is injected at high velocity through the radial grooves 87 and mixed with the chemical (coagulant, flocculent, Bentonite, of activated carbon) entering from the top inlet 90 and through the orifices 92. The two fluids are then discharged into the impact zone 89 to become thoroughly mixed. The mixture of fluids exits the fluid mixer through the outlet 94.

[0063] FIGS. 6-11 depict a system 71, 72, 75, or 77 for mixing chemicals in powder or granular form in liquid so they can be fed into the contaminated wastewater stream that is to be treated and clarified. The chemical mixing system 71, 72, 75, or 77 combines the mixing system for dry powders disclosed in U.S. Pat. No. 6,254,267 with the fluid mixer disclosed in co-pending patent application Ser. No. 09/879,496 referenced above. FIG. 6 depicts the chemical powder and liquid mixing system 71, 72, 75, or 77 and identifies basic system components for a particular embodiment of the present invention. FIGS. 6-11 depict the system 71, 72, 75, or 77 during various stages of operation. The chemical mixing system 71, 72, 75, or 77 consists of a dry powder mixing system 95 for dissolving solid chemicals that go into solution when mixed with water, such as coagulants and flocculants, and for wetting and dispersing solid chemicals that remain as solids in water, such as Bentonite and activated carbon, and a fluid mixing system 98 for diluting and continuously stirring chemicals to the level needed for wastewater treatment based on the amount of contamination present.

[0064] The dry powder mixing system 95 consists of a wetting housing 106 with 107; a nozzle 108 in the upper part of the wetting housing 106; a second the lower part of the wetting housing 106; three valves 100, 101, and 114 d piping 102 and 114 to control the incoming water to the nozzles 103 and pump 104 with associated piping 107 and a shutoff valve 111 to transfer water mixture out of the wetting housing 106; and outlet valve 112 he upper part of the housing 106 with associated piping 121 connected to g system 96; a fill line 113 and valve 118; and a vent valve 110.

[0065] The fluid mixing system 96 consists of a tank 119 with an outlet port 97 t 123; a fluid mixer 124 mounted on top of the tank 119; distributors 125 the center of the tank 119; and a circulation pump 99 with a suction line 98, e 117, and piping 116 and 122 connecting the pump 99 to the fluid mixer

[0066] Referring to FIG. 7, in operation dry chemicals in powder or granular form in the wetting container 106 through the access port 108.

[0067] Referring to FIG. 8, with outlet pump 104 turned off and shutoff valve 111 e vent valve 110 and fill valve 118 opened, the wetting tank 106 is filled 0 from mixing tank 119 through piping 113. When the wetting tank 106 is e 100 and fill valve 118 are closed.

[0068] Referring to FIG. 9, with upper outlet valve 112; inlet valves 100, 101, and et valve 117 opened, circulating pump 99 is turned on. The arrows indicate of flow. Water 120 is drawn from tank 119 by circulating pump 99 through suction pipe 98 and pumped through piping 122 and fluid mixer 124 and dispersed and mixed with existing water 120 in tank 119 by distributors 125 positioned at various levels in the center of tank 119. Valve 117 in circulating line 122 is partially closed and water flows through valve 100 then divided into two streams to flow to the upper nozzle 109 and lower nozzle 103.

[0069] Adjusting inlet valves 101 and 115 controls the amount of water directed to the nozzles 103 and 109. The swirling spray of lower nozzle 103 lifts and wets or dissolves the lower part of powder 105 as the water flows upward and out through outlet valve 112, The swirling spray of upper nozzle 109 intercepts the dry powder as it flows upward. The swirling water sprayed in apposing directions wets and mixes the chemical powder with the water. The chemicals that dissolve in the water continue to flows upward out the wetting container 106 with the water and flow to the fluid mixer 124 where they are thoroughly mixed with the circulating water from piping 122 then dispersed throughout the existing water 120 in tank 119 by the distributors 125. The heavy chemicals that do not dissolve remain in the wetting container 106 as solids and become thoroughly wet.

[0070] Referring to FIG. 10, to transfer the solids from the wetting container 106, outlet valve 111 is opened and outlet pump 104 is turned on. Outlet valve 112 at the top of the wetting chamber 106 is closed. The water and wetted powder is drawn by outlet pump 104 from the wetting container 106 and flows through piping 107, outlet valve 111, and piping 121 to the fluid mixer 124 where they are thoroughly mixed with the circulating water from piping 122 then disperse in the existing water 120 in tank 119 by the distributors 125. When all solids chemicals are removed from the wetting container 106, partially closed valve 117 is opened completely and valve 100 is closed to shutoff he wetting container 106. Vent valve 110 is opened and all water in the ner 106 is transferred and mixed into the water 120 in the tank 119. When t of the wetting container 106, outlet pump 104 is shutdown and vent valve

[0071] Referring to FIG. 11, with all water 120 returned to the tank 119, the mp 99 continues to operate and keeps the chemicals dispersed in the water d into the contaminated water that is to be treated.

[0072] FIGS. 12A and 12B provide an illustration of the distributor 125 positioned in the mixing tank 119. The distributor 125 is simple in construction but at dispersing the incoming fluid throughout the water 120 in the mixing distributor 125 consists of an inlet 128, a top disc 126, a bottom disc 129, old the top disc 126 and bottom disc 129 separated by a spacer 131, and an he arrows indicate the direction of fluid flow. The size of the spacer 131 ow far apart the discs are maintained and the amount of fluid dispersed by r 125 at any specific location in the mixing tank 119. The bottom outlet 130 o continue flowing to the distributors lower in the mixing tank 119.

[0073] FIGS. 13A-14 depict a fluid mixer applied as a dissolved gas generator 45, IGS 1-4) employing dynamic forces of fluid flow obtained with a radial-grooved where atmospheric air or other low pressure gas is used as an oxygen supply to the mixer by venturi suction. FIGS. 13A and 13B provide three-dimensional of a typical radial-grooved ring 135 and a combination venturi-orifice ring 132 having 12 orifices 131 and 12 venturi 133 to fit into the radial grooves 134 of the d ring 135.

[0074] FIG. 14 provides a vertical cross-sectional view of the fluid mixer 45, 55, ly consisting of a cylindrical donut housing 140, a combination venturi-orifice 32, a radial-grooved ring 135, a lower cylinder 137, and a lower cap 136. al donut housing 140 has a gas separation chamber 143 to separate excess he liquids so the gases can by discharged while retaining the liquid. The radial-grooved ring 135 serves as an impact zone 147 into which the ams of the liquid-gas mixture flowing at high velocity are directed to collide r.

[0075] An inlet gas-metering valve 145 connected to the gas inlet 144 of the nut housing 140 regulates the amount of gas supplied during operation. An tering valve 142 connected to the gas outlet 141 of the cylindrical donut egulates the amount of gas discharged from the device during operation.

[0076] Referring to FIG. 14, the liquid enters through inlet 139 and flows into the hannel 146 around the radial-grooved ring 135. The liquid then flows dial grooves 134 where gas is drawn through the orifice ports 131 into each as the liquid flows by the venturi. The liquid-gas mixture in each of the s then injected at high velocity into the impact zone 147 to collide with each quid becomes saturated with gas at this point. The inlet gas-metering valve the amount of gas supplied.

[0077] The saturated liquid 138 flows downward out of the impact zone 147 and area of the lower cylinder 137 where the velocity is decreased. The excess 148 flow upward and return to the impact zone 147. The saturated liquid flow downward and exits through the outlet 149. The excess bubbles 148 ugh the impact zone 147, and the gas is separated from the liquid in the amber 143 and released from the unit through the outlet gas-metering valve

[0078] The amount of gas retained in the separation chamber 143 regulates the n the apparatus. The amount of gas released is adjusted to maintain the liquid ve the impact zone 147, and only a small amount of gas has to be released mber 143. The fluid mixer 55 or 62 is extremely effective at saturating gases with only five parts that can be manufactured in many sizes at low e manufactured in metal or in plastic either machined or injected molded.

Claims

1. An apparatus adapted for separation of solids from liquids or separation of liquids from liquids.

2. The apparatus of claim 1 wherein the apparatus is adapted to utilize a dissolved gas floatation process.

3. apparatus of claim 1 further comprising a gas floatation clarifier.

4. apparatus of claim 1 further comprising a liquid-gas mixer.

5. A method for separation of solids from liquids or separation of liquids from liquids.

6. The method of claim 4 further comprising utilizing gas floatation.

7. The method of claim 3 further comprising supplying dissolved air and mixing of chemicals for use in separation of solids in dissolved air floatation clarifiers.