What is clai med is :
[Clai m 1 ] A bio-tank oxygen replenishment system, comprising: a tank for holding wastewater; a mixer for oxygenating the wastewater; a probe for measuring oxygen concentration of the wastewater in the tank; and a controller responsive to the probe measurements, for regulating the oxygen replenishment rate of the wastewater.
[Clai m 2] The system of claim 1 , including a circulation pump for transferring wastewater from the tank to the mixer, wherein the controller sets the circulation pump speed to optimize the wastewater oxygen concentration. [Clai m 3] The system of claim 2, wherein the controller sets the circulation pump speed based on oxygen concentration information provided by the probe. [Clai m 4] The system of claim 1 , wherein the mixer includes an accelerator head for spinning the wastewater into a down tube.
[Clai m 5] The system of claim 4, wherein the spinning wastewater forms a vortex in the down tube.
[Clai m 6] The system of claim 5, wherein the vortex includes a central evacuated area.
[Clai m 7] The system of claim 1 , wherein the mixer includes an oxygenated head space.
[Clai m 8] The system of claim 7, wherein the head space comprises essentially pure oxygen. [Clai m 9] The system of claim 7, including a sensor for measuring the size of the head space.
[Clai m 1 0] The system of claim 7, including a port for changing the size of the head space.
[Clai m 1 1 ] The system of claim 7, including a baffle for diverting oxygenated wastewater from a down tube outlet, to the head space.
[Clai m 1 2] The system of claim 7, including a conduit for transferring oxygen from the head space for remixing with the wastewater.
[Clai m 1 3] The system of claim 1 , wherein the controller receives real-time oxygen concentration information from the probe.
[Clai m 1 4] The system of claim 1 , wherein the mixer includes a wastewater inlet and a gas inlet.
[Clai m 1 5] The system of claim 1 , wherein the mixer is fluidly coupled to a holding tank.
[Clai m 1 6] The system of claim 1 5, wherein the holding tank is fluidly coupled to a dissolved air flotation system and a corresponding liquid-solid mixer.
[Clai m 1 7] The system of claim 1 , wherein the mixer includes a hydro-cyclone head inlet.
[Clai m 1 8] The system of claim 1 7, wherein the hydro-cyclone head inlet is generally circular, multi-circular, or has an aspect ratio of 24: 1 , 1 0: 1 , 6: 1 , 2.6: 1 or
1 :1 . [Clai m 1 9] The system of claim 1 8, wherein the maximum dissolvable oxygen concentration in the wastewater is distinct for each hydro-cyclone head inlet and corresponding mixer pressure.
[Clai m 20] A bio-tank oxygen replenishment system, comprising: a tank for holding wastewater; a mixer for oxygenating the wastewater; a probe for measuring oxygen concentration of the wastewater in the tank; a controller responsive to the probe measurements, for regulating the oxygen replenishment rate of the wastewater; and a circulation pump for transferring wastewater from the tank to the mixer, wherein the controller sets the circulation pump speed to optimize the wastewater oxygen concentration.
[Clai m 21 ] The system of claim 20, wherein the holding tank is fluidly coupled to a dissolved air flotation system and a corresponding liquid-solid mixer.
[Clai m 22] The system of claim 20, wherein the mixer includes a hydro-cyclone head inlet.
[Clai m 23] The system of claim 22, wherein the hydro-cyclone head inlet is generally circular, multi-circular, or has an aspect ratio of 24: 1 , 1 0: 1 , 6: 1 , 2.6: 1 or
1 :1 .
[Clai m 24] The system of claim 23, wherein the maximum dissolvable oxygen concentration in the wastewater is distinct for each hydro-cyclone head inlet and corresponding mixer pressure. [Clai m 25] The system of claim 20, wherein the controller sets the circulation pump speed based on oxygen concentration information provided by the probe.
[Clai m 26] The system of claim 20, wherein the mixer includes an accelerator head for spinning the wastewater into a down tube.
[Clai m 27] The system of claim 26, wherein the spinning wastewater forms a vortex in the down tube, the vortex including a central evacuated area.
[Clai m 28] The system of claim 20, wherein the mixer includes an oxygenated head space comprising essentially pure oxygen.
[Clai m 29] The system of claim 28, including a sensor for measuring the size of the head space.
[Clai m 30] The system of claim 29, including a port for changing the size of the head space in response to input from the sensor.
[Clai m 31 ] The system of claim 30, including a baffle for diverting oxygenated wastewater from a down tube outlet, to the head space.
[Clai m 32] The system of claim 30, including a conduit for transferring oxygen from the head space for remixing with the wastewater.
[Clai m 33] The system of claim 30, wherein the controller receives real-time oxygen concentration information from the probe.
[Clai m 34] The system of claim 20, wherein the mixer includes a wastewater inlet and a gas inlet.
[Clai m 35] A bio-tank oxygen replenishment system, comprising: a tank for holding wastewater; a mixer for oxygenating the wastewater, wherein the mixer includes a hydro- cyclone head inlet, a wastewater inlet and a gas inlet; an accelerator head in the mixer for spinning the wastewater into a vortex in a down tube, the vortex including a central evacuated area; a probe for measuring oxygen concentration of the wastewater in the tank; an oxygenated head space in the mixer comprising essentially pure oxygen; a sensor for measuring the size of the head space; a port for changing the size of the head space in response to input from the sensor; a baffle for diverting oxygenated wastewater from a down tube outlet, to the head space; a circulation pump for transferring wastewater from the tank to the mixer; and a controller for regulating the oxygen replenishment rate of the wastewater, wherein the controller sets the circulation pump speed based on real-time oxygen concentration information provided by the probe.
[Clai m 36] The system of claim 35, wherein the holding tank is fluidly coupled to a dissolved air flotation system and a corresponding liquid-solid mixer. [Clai m 37] The system of claim 35, wherein the hydro-cyclone head inlet is generally circular, multi-circular, or has an aspect ratio of 24: 1 , 1 0: 1 , 6: 1 , 2.6: 1 or 1 :1 .
[Clai m 38] The system of claim 37, wherein the maximum dissolvable oxygen concentration in the wastewater is distinct for each hydro-cyclone head inlet and corresponding mixer pressure. [Clai m 39] The system of claim 35, including a conduit for transferring oxygen from the head space for remixing with the wastewater. |
BIO TANK/OXYGEN REPLENISHMENT SYSTEM
DESCRI PTION
BACKGROUND OF THE INVENTION
[Para 1 ] The present invention generally relates to the treatment of contaminated liquid, such as wastewater. More particularly, the present invention relates to a method for removing contaminants from a liquid by use of a gas replenishment system that controls levels of dissolved oxygen in the liquid. The oxygen contains species capable of converting dissolved solids into carbon dioxide and suspended solids, which are more easily separated from the liquid than dissolved solids. The present invention also pre-treats the wastewater, if needed, to remove large particles, fats, grease, and physically emulsified oils. Membrane separation such as nano filtration or reverse osmosis is also used to remove non-biodegradable organic materials and inorganic ions.
[Para 2] Industrial wastewater contains various pollutants. Such pollutants are present as large particles (larger than one micron), charge stabilized colloidal particles (oil and water emulsions, etc.) and dissolved species such as sugar, proteins, or inorganic ions. Regulations require removal of most or all of such pollutants before wastewater discharge into a publicly owned treatment works
(POTW).
[Para 3] Complex treatment methods have been designed to remove the wide variety of physical and chemical species. In one instance, membrane and
separation processes are used. Micro-filtration is used to remove large particles, while ultra-filtration is used to remove colloids and proteins, and reverse osmosis is used to remove ions and small species. But, subsequent cleaning is expensive and often is inefficient as the membranes get fouled with various species present in water. Another process for removing large particles from water is coagulation with inorganic species, such as ferric ions, ferrous ions, or aluminum ions, to neutralize particle charge. Subsequent sedimentation can be achieved in clarifiers. But, this process is slow and consequently requires large tanks. [Para 4] Colloidal materials and micro-molecules must be removed after the removal of larger particles. Biodegration is a particularly popular way of removing such materials. A collection of active microorganisms that grow in anaerobic or aerobic tanks may be capable of metabolizing these biodegradable materials. Anaerobic degradation is generally efficient, but, it can take months or even years to destroy biodegradable organic pollutants. Aerobic degradation is actually faster and can be used to treat wastewater with much lower organic loads. Low organic loads have chemical oxygen demand (COD) and biological oxygen demand (BOD) not larger than around 2,000 parts per million (ppm).
[Para 5] Biological aerobic industrial wastewater treatment should use water having high or varying loads of organic materials. Low organic loads can upset the biological aerobic wastewater treatment process. Unfortunately, most industrial wastewater is rich in nutrients and continuity varies in composition. [Para 6] Accordingly, there is a continuing need to provide an industrial wastewater treatment system incorporating aerobic biodegradation while
accommodating the amount of nutrients in the industrial wastewater over time. The present invention fulfills these needs and provides further related advantages.
SUMMARY OF THE INVENTION
[Para 7] The present invention discloses a bio-tank replenishment system for treating contaminated liquid, such as wastewater. The wastewater contains biological species capable of converting dissolved solids into carbon dioxide and suspended solids. The carbon dioxide and suspended solids are more easily separated from water than dissolved solids. Wastewater pre-treatment removes large particles, fats, grease, and other physically emulsified oils. Membrane separation, such as nanofiltration or reverse osmosis is also used to remove nonbiodegradable organic materials and inorganic ions.
[Para 8] The purified wastewater is transferred to a bioreactor tank for further decontamination therein. Biological species within the bioreactor tank consume oxygen dissolved in the wastewater to perform normal aerobic bodily functions. Carbon dioxide and suspended solids are natural by-products of such bodily functions. The oxygen concentration in the wastewater must be replenished so the biological species may continue converting and removing the dissolved solids within the wastewater.
[Para 9] An oxygen probe disposed in the bioreactor tank wastewater measures real-time oxygen concentrations therein. A controller responsive to the real-time oxygen concentration measurements regulates the oxygen replenishment rate of the wastewater via a circulation pump. The circulation pump transfers wastewater
from the tank to a mixer. The controller changes the speed of the circulation pump according to oxygen concentrations in the bioreactor tank. The controller also manages the rate of oxygenated gas entering the mixer, the size of an evacuated area formed in a wastewater vortex, the size of a mixer head space, and pressure within the mixer. The controller controls the devices that adjust each of these variables in order to optimize the amount of dissolvable oxygen within the wastewater during oxygen replenishment in the mixer.
[Para 1 0] The mixer includes a wastewater inlet for receiving the wastewater stream and a gas inlet for adding oxygen to the wastewater. The wastewater inlet may comprise hydro-cyclone head inlet that is generally circular, multi-circular, or has an aspect ratio of 24: 1 , 1 0: 1 , 6: 1 , 2.6: 1 or 1 :1 . Maximum dissolvable oxygen concentration in the wastewater is distinct for each hydro-cyclone head inlet and corresponding mixer pressure.
[Para 1 l ] The mixer also includes an accelerator head and a down tube for vigorously mixing the wastewater and oxygen. The accelerator head spins the wastewater into a vortex in the down tube. Oxygen inputted into the down tube may form a central evacuated area within the vortex. A sensor integral to the mixer measures the characteristics of the evacuated area, such as size, shape, length, and diameter. The mixer also includes an oxygenated head space comprising essentially pure oxygen. Another sensor is capable of measuring the size of the head space to ensure further efficient oxygenation of the wastewater stream exiting the down tube. Accordingly, a baffle diverts the oxygenated wastewater from the down tube outlet to the head space. Large oxygen bubbles
not dissolved within the wastewater stream float into the head space. Additional oxygen from the head space is dissolved in the wastewater before the wastewater enters the bioreactor tank. A conduit formed in the top of the mixer retains the non-dissolved oxygen for selective reintroduction with the wastewater in the down tube of the mixer.
[Para 1 2] The oxygen replenishment system may also be fluidly coupled to a holding tank, a dissolved air flotation system and a corresponding liquid-solid mixer. The dissolved air flotation system and liquid-solid mixer are used to remove larger particles such as fats, grease, and other physically emulsified oils. [Para 1 3] Other features and advantages of the present invention will become apparent from the following, more detailed description, when taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
BRIEF DESCRIPTION OF DRAWINGS
[Para 14] The accompanying drawings illustrate the invention. In such drawings:
[Para 1 5] FIG. 1 is a diagrammatic view of a wastewater treatment system embodying the present invention;
[Para 1 6] FIG. 2 is a schematic view of a liquid-solid mixer for use with the present invention;
[Para 1 7] FIG. 3 is a cross-sectional view of the liquid-solid mixer in FIG. 2, taken generally along the line 3-3;
[Para 1 8] FIG. 4 is a partially sectioned view of a liquid-solid mixer used in accordance with the present invention;
[Para 1 9] FIG. 5 is a diagrammatic view of a gravity suspension system for removing colloidal materials from the wastewater;
[Para 20] FIG. 6 is a schematic view of a bioreactor tank and system for mixing oxygen and biological species to perform aerobic degregations;
[Para 21 ] FIG. 7 is an alternative schematic view of a liquid-oxygen mixer;
[Para 22] FIG. 8 is a sectional view of another liquid-oxygen mixer usable in accordance with the present invention;
[Para 23] FIG. 9 is a schematic view illustrating the path of a single particle at three time intervals within a liquid-oxygen mixer;
[Para 24] FIG. 1 0 illustrates schematic representations of the resulting velocity vector of the single particle at the three time intervals shown in FIG. 9;
[Para 25] FIG. S 1 I a-I I h are diagrammatic representations of various exit valves incorporated into the liquid-oxygen mixer; and
[Para 26] FIG. 1 2 is a chart illustrating the vessel pressure against dissolved oxygen content of water for the various exit valves in FIGS. 1 1 a-1 1 h.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Para 27] As shown in the accompanying drawings, for purposes of illustration, the present invention resides in a system for treating wastewater liquid to advantageously utilize aerobic biological species to convert dissolved solids into carbon dioxide and suspended solids. As shown in the exemplary drawings for
purposes of illustration, the present disclosure for a wastewater treatment system is referred to generally by the reference numeral 1 0. Turning now to the representative figures in the specification, FIG. 1 illustrates the wastewater treatment system 10 having a liquid-solid mixer 1 2 in fluid communication with a floatation tank 1 4. The floatation tank 1 4 is a gravity separation system, such as that described in U.S. Patent No. 6,797,1 81 , the contents of which are herein incorporated by reference. Once the contaminated wastewater, including large particles, fats, grease, and physically emulsified oils and the like are removed from the contaminated wastewater via the floatation tank 1 4, the purified wastewater is moved to a holding tank 1 6. A pump 1 8 pressurizes the purified wastewater for transfer from the holding tank 1 6 into a liquid-oxygen mixer 20. The liquid- oxygen mixer 20 pressurizes and oxygenates the purified wastewater for introduction into a bioreactor tank 22. The purified wastewater still contains dissolved particles such as sugars, proteins, or inorganic ions that must be removed before the liquid stream is discharged into a POTW. The liquid-oxygen mixer 20 is commonly referenced as a Liquid Cyclone Particle Positioner (LCPP). The remaining dissolved solids are converted into carbon dioxide and suspended solids in the bioreactor tank 22. The remaining waste is thereafter more easily separated from the water in the bioreactor tank 22 after oxygenation via the liquid-oxygen mixer 20. The waste is discharged and the decontaminated water is transferred to a POTW or the like.
[Para 28] The liquid-solid mixer 1 2 is fluidly connected to a source of wastewater or other fluid to be treated. Typically, a pump (not shown) is used to pressurize
and direct a stream of the contaminated wastewater through a contaminated wastewater inlet 24 (FIG. 2) of the liquid-solid mixer 1 2. As illustrated in FIG. 3, the contaminated wastewater is directed through the inlet 24 and into a liquid accelerator 26 that increases the linear velocity of the contaminated wastewater in the liquid-solid mixer 1 2. The pressurized contaminated wastewater is tangentially accelerated by the liquid accelerator 26 into a central cartridge 28 of the liquid-solid mixer 1 2. Here, the pressurized contaminated wastewater contacts an inner surface 30 (FIG. 4) of the central cartridge 28 at high velocity and is thereafter forced into a spinning motion within the central cartridge 28. Typically, the central cartridge 28 is tapered such that a resulting vortex 32 has a larger upper diameter 34 and a smaller lower diameter 36. The contaminated wastewater then exits the liquid-solid mixer 1 2 through the bottom of a down tube 38 via an exit 40. The liquid-solid mixer 1 2 forces the liquid into a rotational flow subject to angular momentum. This forms the vortex 32 illustrated in FIG. 2. An additive inlet 42 may introduce gas, chemicals, or solid additives for treatment of the contaminated wastewater stream.
[Para 29] In a particularly preferred embodiment in FIG. 4, a detailed liquid-solid mixer 1 2 is shown. The liquid-solid mixer 1 2 is similar to a hydrocyclone, but, unlike a conventional single port hydrocyclone, the liquid-solid mixer 1 2 has a 2- stage delivery mechanism. The liquid-solid mixer 1 2 comprises an upper reactor head 44 and the lower down tube 38 through which the contaminated wastewater and mixed additives exit at the outlet 40 thereof. The liquid-solid mixer 1 2 is designed such that the reactor head 44 imparts a spinning motion to the
contaminated wastewater upon entry via the contaminated wastewater inlet 24. The vortex 32 forms in the down tube 38 and mixes the additives, liquid, contaminants, and entrained gas typically substantially homogenously. [Para 30] The reactor head 44 comprises the inlet 24 formed in an outer housing 46 such that the contaminated wastewater inlet 24 is in fluid communication with a plenum 48. The contaminated wastewater stream flows into the reactor head 44 via the contaminated wastewater inlet 24 and into the plenum 48, as defined by the space between the central cartridge 28 and the outer housing 46. A base 50 and a lid 52 enclose the remainder of the reactor head 44 and seal the plenum 48 to enable pressure build-up within the reactor head 44 and corresponding down tube 38. The contaminated wastewater stream is pressurized in the plenum 48 around the exterior of the central cartridge 28 disposed within the enclosure of the reactor head 44. The central cartridge 28 is a cylindrical or multi-faceted member in fluid communication with the down tube 38. The central cartridge 28 includes a plurality of tangential ports 54 extending through a cartridge wall 56. The contaminated wastewater is directed through the tangential ports 54 and into the central cartridge 28 at a generally tangential direction to the inner surface 30 thereof. The pressurized contaminated liquid that fills the plenum 48 forcingly enters the interior of the central cartridge 28 having a spinning motion imparted thereon to form the vortex 32 within the central cartridge 28 and the down tube 38. The central cartridge 28 can be configured as a hexagon, octagon, or any other multi-faceted structure. The tangential ports 54 are formed in at least one facet thereof, and more preferably in every facet thereof as illustrated in FIG. 4.
The number of open tangential ports 54, the diameter of the tangential ports 54, the diameter of the inner surface 30 of the central cartridge 28, and the diameter of the down tube 38 determines the speed the contaminated wastewater spins and passes through the liquid-solid mixer 1 2.
[Para 31 ] The tangential ports 54 are configured to receive a plurality of removable restrictor plugs 58. Typically, the tangential ports 54 are drilled and tapped to include threads that allow the removal of the threaded restrictor plugs 58 via a screwdriver or other tool. Of course, other methods of removably inserting the restrictor plugs 58 within the tangential ports 54 will be appreciated by those skilled in the art. The amount of mixing energy imparted to the spinning contaminated wastewater within the central cartridge 28 is regulated by the quantity of open tangential ports 54. Inserting the removable restrictor plugs 58 into the tangential ports 54 decreases the quantity of contaminated wastewater entering the central cartridge 28 and correspondingly decreases the rotational speed of the contaminated wastewater therein. Oppositely, removing the removable restrictor plugs 58 from the tangential ports 54 effectively increases the quantity of open tangential ports 54. This increases the flow rate of the contaminated wastewater into the central cartridge 28 and increases the spinning speed (mixing energy) of the contaminated wastewater therein. Regulating the quantity of open tangential ports 54 also affects the flow rate of the contaminated liquid into the central cartridge 28, the volume of the contaminated wastewater within the central cartridge 28 at any given time, the pressure in the plenum 48, the central cartridge 28 and the down tube 38, and the overall process of mixing
any additives into the contaminated wastewater. Such variables help facilitate the process of homogeneously mixing said additives within the liquid-solid mixer 1 2. [Para 32] Additives, such as pH/redox chemistries, flocculants, coagulants, clay, diotomatious earth, etc. are typically added to the contaminated wastewater stream to alter the iso-electric chemistry of the mixture thereof and to bind suspended solids therein. The process of adding the additive is accomplishable upstream of the contaminated wastewater inlet 24 formed in the reactor head 44 of the liquid-solid mixer 1 2. But, the liquid-solid mixer 1 2 can also include an additive inlet 42 to introduce such additives immediately before or during mixing. Alternatively, the additives are added to the contaminated wastewater stream before mixing via an upstream inlet 60 as shown in FIG. 4. The additive inlet 44, as shown in FIGS. 2 and 4, is formed in the lid 52 of the reactor head 44. Introduction of the additives through the additive inlet 42 creates a centrally evacuated area 62 within the reactor head 44 and extending down into the down tube 38. The contaminated wastewater enters the central cartridge 28 via the tangential ports 54 having the spinning motion around the inner surface 30 of the central cartridge 28. The pressurized introduction of the additives via the additive inlet 42 creates the centrally evacuated area 62 by forcing the contaminated liquid toward the inner surface 30. The spinning contaminated wastewater stream absorbs and entrains the additives introduced into the mixer 1 2 via the additive inlet 42. The centrally evacuated area 62 forms interior to the vortex 32 and causes further mixing of the additives and wastewater within a cyclone spin chamber 64. The spinning contaminated wastewater absorbs and entrains the
additives introduced into the mixer 1 2 via the additive inlet 42. A sensor 66 having an upper gauge 68 and a lower gauge 70 (FIG. 5) may electrically, sonically, visually, or otherwise measure the size and location of the centrally evacuated area 62 within the down tube 38. Furthermore, the sensor 68 may be used to determine the size, characteristics, and termination location of the centrally evacuated area 62 and the physical shape of the vortex 32. A controller determines the amount of replenishment additives needed to replace the additives absorbed into the contaminated wastewater stream and carried out through the outlet 40 and into the floatation tank 14.
[Para 33] It was conventionally thought that longer mixing time (1 -1 0 minutes) at lower mixing energies (30-1 00 revolutions per minute [RPM] of a mechanic mixer) was needed for optimum flocculation. But, this is not the case. Shorter mixing times (5-10 seconds) with higher mixing energies (up to 4,000 RPM with a mechanical mixer) yielded cleaner water with lower turbidity and larger, easier floating floes. Thus, the mixing inside the central cartridge 28 of the liquid-solid mixer 1 2 may last only a few seconds while yielding excellent floes without any mechanical pre-mixing or potential polymer breakage. Mixing energy or speed at which the contaminated wastewater is passed through the liquid-solid mixer 1 2 is determined in large part by the number of open tangential ports 54 set to receive the contaminated wastewater, as previously discussed. [Para 34] A plurality of the liquid-solid mixers 1 2 may be used together depending upon the type and quantity of chemical additives, desired mixing energy, and desired mixing time required to optimize separation. The integration
of such a plurality of the liquid-solid mixers 1 2 is more fully described in U.S. Patent No. 6,964,740, the contents of which are herein incorporated by reference. Such a plurality of the liquid-solid mixers 1 2 allows sequential injection of additives at optimum mixing energies and for optimum mixing durations for each chemical constituent individually. Additionally, the amount and type of additives, the size and location of the centrally evacuated area 62, the speed, pressure and flow rate of the contaminated wastewater in the vortex 32, and the size of the down tube 38 may all be varied within each respective liquid-solid mixer 1 2. [Para 35] FIG. 5 illustrates the process of removing solid waste from the contaminated wastewater stream via dissolved air floatation (DAF). The contaminated wastewater having the chemical additives added therein exits the liquid-solid mixer 1 2 at the outlet 40 and flows through a tube 72, a pressure valve 74 and into a nucleation chamber 76. The pressure valve 74 regulates the flow rate of the contaminated wastewater stream having the mixed chemical additives therein. The flow rate of the contaminated wastewater into the nucleation chamber 76 and through a cavitation plate 78 directly affects the rate of nucleation and flocculation of the solid waste particles within the contaminated wastewater. In general, the floatation tank 1 4 removes the solid waste 80 from the contaminated wastewater and filters the purified wastewater from the floatation tank 1 4 via a purified wastewater outlet 82. Removed purified wastewater is stored in the holding tank 1 6 (FIG. 1 ).
[Para 36] More specifically, the generally homogenous contaminated wastewater stream flows into the nucleation chamber 76 via the tubing 72. The cavitation
plate 78 disposed within the nucleation chamber 76 has a plurality of apertures (not shown) formed therein to initiate nucleation and bubbling before the wastewater stream enters a corresponding bloom chamber 84. The bubbles that form in the nucleation chamber 76 are extremely small and attached to the flocculants within the contaminated wastewater stream. The resulting bubbles combine and increase in size in the bloom chamber 84. A solid flocculant froth of the solid waste 80 forms at the surface of the floatation tank 14 as the small bubbles increase in size and float to the top thereof. The solid waste 80 is skimmed from the surface of the floatation tank 14 via a set of paddles 86. The skimmed solid waste 80 is placed in a dewatering subsystem 88. The denser treated wastewater (purified wastewater 90) sinks to the bottom of the floatation tank 1 4 for removal thereof via the purified wastewater outlet 82. The purified wastewater is thereafter stored in the holding tank 1 6 (FIG. 1 ) before being pumped into the liquid-oxygen mixer 20 for eventual treatment in the bioreactor tank 22. The purified wastewater in the holding tank 1 6 still contains additives and other nano-particle waste therein. Such additives and waste are accordingly removed via the bioreactor tank 22. Further water extracts from the dewatering subsystem 88 are re-circulated back into the liquid-solid mixer 1 2 for reprocessing. The corresponding solid waste 80 in the dewatering system 88 is thereafter removed from the treatment system 1 0 altogether. [Para 37] FIG. 6 is a diagrammatic illustration showing the purified wastewater being further treated by the bioreactor tank 22. The purified wastewater, as shown in FIG. 1 , is transferred from the holding tank 1 6 to the bioreactor tank 22
via the pump 1 8 and the liquid-oxygen mixer 20. The purified wastewater pumped from the holding tank 1 6 (FIG.1 ) is denoted as a liquid source 90 in FIG. 6. The liquid source 90 encompasses any liquid stream capable of being treated within the scope of the bioreactor tank 22. Preferably, the liquid source 90 is the purified wastewater stored in the holding tank 1 6. The purified wastewater is introduced into the liquid-oxygen mixer 20 via a purified wastewater inlet 92. In the embodiment of FIG. 6, the liquid-oxygen mixer 20 includes a second recirculation inlet 94 that receives partially treated purified wastewater from a tank 96 via a circulation pump 98 and a corresponding re-circulation line 1 00. A controller 1 02 connected to an oxygen probe 104 regulates the re-circulation pump 98 to optimize the circulation of the purified wastewater within the bioreactor tank 22, as is more fully described herein. The controller 102 is also connected to the other components of the treatment system 10, including the various pumps, valves, cavitation plates, mixers (liquid-solid and liquid-oxygen), inlets, outlets, fans, sensors and the dewatering subsystem 88 components. The controller 1 02 processes information gathered from these devices and, accordingly, manages the overall treatment system 1 0 via these devices. [Para 38] The liquid-oxygen mixer 20 integrated into the bioreactor tank 22 is distinguishable from other liquid-oxygen mixing devices. For instance, in M. L. Jackson, "Energy Effects in Bubble Nucleation," Industrial and Engineering Chemistry Research, Vol. 33, pp. 929-933 (1 994), it was shown that much higher gas transfer in bubble nucleation efficiencies are achieved if gas is saturated into liquid at lower pressure and then pumped or transferred into a floatation tank at
higher pressure. The liquid-oxygen mixer 20 is an ideal device to achieve such liquid-gas mixing. Pressure inside of the liquid-oxygen mixer 20 can always be different from the pressure used to pump the purified wastewater stream. Pressure is usable to precisely adjust gas dosage (oxygen, ozone, carbon dioxide) to replenish the saturation pressure gas loss within less than 1 %. Increasing the flow rate of the purified wastewater enables delivery of 37 ppm of oxygen at 1 5 pounds per square inch (psi) as efficiently as at 90 psi. Higher oxygen concentrations are slower to achieve at lower pressure, while increasing flow rate (transfer pressure) achieves almost equal oxygen rates faster. Using one or two liquid-oxygen mixers 20 at low pressures is therefore more efficient than using one liquid-oxygen mixer 20 at a very high pressure.
[Para 39] Important to the process of the bioreactor tank 22 is the fast and efficient biodegration of saturated sludge particulates via aerobic microorganisms embedded within food particles, dissolved organics, and oxygen. The liquid- oxygen mixer 20 is, for similar reasons as the liquid-solid mixer 1 2, an excellent mixer with high collision efficiencies. Microorganisms are large enough to be moved like particulates throughout the liquid-oxygen mixer 20, similar to the spinning motion imparted to the contaminated wastewater and additives in the central cartridge 28 of liquid-solid mixer 1 2. Thus, the microorganisms have varying angular and vertical velocities within a cyclonic mixer 1 06 (FIGS. 7 & 8). As in the case of gas (oxygen), such movement at high velocity significantly enhances destruction of gradients in oxygen and in food concentration near the microorganisms because the microorganisms consume food and oxygen nearby
and create such gradients. Such mixing also aims to remove gradients in concentration of the products of microbial metabolism.
[Para 40] The angular movement of a microorganism 1 08, represented by the dot in FIG. 7, is illustrated in three sequential positions within the cyclonic mixer 1 06 of the liquid-oxygen mixer 20. The position of the microorganism 1 08 is shown in three separate time periods denoted by Ti , T2, and T3. The time sequences Ti , T2, and T3 illustrate the position of the microorganism 108 at various radial positions within the spiraling purified wastewater stream within the cyclonic mixer 1 06. The corresponding times Ti , T2, and T3 correlate to the three various radii π , r2, and r3, respectively, of the spiraling purified wastewater stream within the cyclonic mixer 1 06. FIG. 8 charts resulting velocity vectors 1 10, 1 1 0', 1 1 0" of the microorganism 1 08 at the three exemplary time periods Ti , T2, and T3. The resulting velocity vector 1 10 is mainly radial when the microorganism 1 08 is adjacent to the solid inner-surface of the cyclonic mixer 1 06. The resulting velocity vectors 1 1 0', 1 1 0" become predominantly axial, or extending downwardly into the cyclonic mixer 106, as the microorganism 1 08 moves toward the center of the cyclonic mixer 106 at times T2 and T3. The microorganism 108 is defined in the illustrations in three distinct locations at three sequential times. But, it is to be understood that time is a continuum and thus radial and actual velocity of the microorganism 1 08 is in continuous flux.
[Para 41 ] The present disclosure illustrates two types of liquid-oxygen mixers 20, 20' in FIGS. 7 and 8, respectively. These liquid-oxygen mixers 20, 20' entrain oxygen and liquid such that the aerobic activity of the biological microorganisms
may further clean the purified wastewater processed in the bioreactor tank 22. Specifically, the liquid-oxygen mixers 20, 20' are used to dissolve and entrain oxygen in the purified wastewater stream. The liquid-oxygen mixers 20, 20' are similar in construction and operation. Similar reference numerals are identified on each of the liquid-oxygen mixers 20, 20' to denote similar or identical components.
[Para 42] Purified wastewater from the holding tank 1 6 or the floatation tank 14 is pumped through the purified wastewater inlet 92, 92' and into the cyclonic mixer 1 06, 1 06'. The cyclonic mixer 106, 1 06' includes an accelerator head 1 1 2, 1 1 2' for imparting a spinning motion to the purified wastewater stream. The accelerator head 1 1 2, 1 1 2' is similar to the tangential ports 54 formed in the central cartridge 28 of the reactor head 44 in FIG. 4. In one embodiment in FIG. 7, the cyclonic mixer 1 06 is a generally straight tube extending the length of a pressure chamber 1 1 4. Alternatively, as illustrated in FIG. 8, the cyclonic mixer 1 06' is varyingly shaped, including being tapered. In both instances, the cyclonic mixers 1 06, 106' extend to approximately the bottom of the vessel 1 14, 1 14'. [Para 43] Compressed oxygen or air is introduced into the purified wastewater stream either upstream of the accelerator head 1 1 2, 1 1 2' or downstream via placement directly into the cyclonic mixer 106, 1 06'. As illustrated in FIGS. 7 and 8, a gas inlet 1 1 6, 1 1 6', respectively, is in fluid communication with the purified wastewater inlet 92, 92'. Alternatively, gas, such as oxygen or air, may also be introduced directly into the vessel 1 14, 1 1 4' via an inlet/outlet 1 1 8, 1 1 8'. The inlet/outlet 1 1 8, 1 1 8' helps maintain a head space 1 20, 1 20' of compressed gas to
further oxygenate the purified wastewater within the vessel 1 14, 1 14'. If less oxygen in the vessel 1 1 4, 1 14' is desired, the head space 1 20, 1 20' is decreased by opening the inlet/outlet 1 1 8, 1 1 8' to allow the pressurized gas within the head space 1 20, 1 20' to escape. The head space 1 20, 1 20' may also be decreased by releasing and recycling oxygen back into the down tube 1 06, 106' by means of a conduit 1 21 , 1 21 '. Oppositely, the inlet/outlet 1 1 8, 1 1 8' is opened and pressurized oxygen is added to the head space 1 20, 1 20' of the vessel 1 14, 1 1 4' to increase the amount of oxygen within the head space 1 20, 1 20' of the vessel 1 14, 1 14'. Oxygen in the head space 1 20, 1 20' is entrained in the purified wastewater after exiting the cyclonic mixer 106, 1 06'. The oxygenated purified wastewater exits the cyclonic mixer 1 06, 1 06' and flows upward from the bottom of the cyclonic mixer 1 06, 106' and through the angular base formed by a baffle 1 24, 1 24'. Accordingly, the purified wastewater exits the baffle 1 24, 1 24' near the top of the vessel 1 1 4, 1 1 4'. Large bubbles not entrained in the purified wastewater stream immediately rise to the head space 1 20, 1 20'. The remaining oxygenated purified wastewater and small entrained bubbles within the vessel 1 14, 1 14' flow downwardly to a discharge outlet 1 22, 1 22' and into the bioreactor tank 22 for further processing and decontamination in the tank 96. The aerobic microorganisms use the oxygen to convert the dissolved solids into suspended solids and carbon dioxide in the tank 96. As further shown in FIG. 7, an oxygen sensor 1 26 monitors the size of the head space 1 20 by sensing the amount of compressed gas within the vessel 1 1 4. The oxygen sensor 1 26 is in electrical communication with the controller 1 02 such that optimal oxygen content is
dissolved within the purified wastewater stream before placement into the tank 96. Compressed air is added to the vessel 1 1 4 while the head space 1 20 is above the upper oxygen sensor 1 28 and the compressed gas supply is shut off when the head space 1 20 falls below the lower oxygen sensor 1 30. [Para 44] The oxygenated purified wastewater stream exits the liquid-oxygen mixer 20, 20' into the tank 96 via a discharge orifice 1 32 as shown in FIG. 6. Microorganisms within the tank 96 are circulated via a fan 1 34 submerged within the purified wastewater. Corresponding oxygen levels within the tank 96 are monitored by the oxygen probe 1 04. Controlling dissolved oxygen levels is necessary to promote the activity of the biological species. The biological species are the instrument through which the dissolved contaminates are more easily separated from the purified wastewater. The biological species consume dissolved oxygen from the water to perform normal bodily functions. Tremendous quantifies of organic agents are necessary to convert contaminants in the purified wastewater from dissolved to suspended solids. Accordingly, tremendous amounts of oxygen must be replaced to promote such a conversion. [Para 45] The rate of oxygen consumption in the process of the present invention is not fixed due to the complex variety of biological species in the by-products that each species produces. Oxygen consumption rates are relatively slow at the beginning of the process. Biological species divide and increase in population once a particular dissolved contaminant in the purified wastewater is consumed. Such a particular species may increase in size by a factor of two. These offspring repeat the process and consume more dissolved contaminants. The oxygen
depletion rate increases as the population of species grows until either the contaminant level is depleted or the available dissolved oxygen level is depleted. In either case a specific species population begins to dwindle. [Para 46] The result of such a "rise" and "fall" of biological activity is a generation of by-products that must, in turn, be consumed by a second set of biological agents. The second set of biological agents go through a similar "rise" and "fall" cycle as the original set of biological agents. The process, again repeats, for the corresponding third set of biological agents and so on. The process continues to repeat and cycle through a given amount of biological species within the purified wastewater. The process continues until all by-products of the consumption tail off. Dissolved oxygen is consumed by each succeeding wave of biological species in this process. The overall consumption of the dissolved oxygen dwindles with the amount of generated by-product.
[Para 47] The present invention addresses this fluctuation in dissolved oxygen content by use of the dissolved oxygen probe 1 04 submerged in the purified wastewater in the tank 96. The controller 1 02 receives a signal from the dissolved oxygen probe 104 in order to properly regulate the oxygen content within the purified wastewater in the tank 96. The controller 1 02 may regulate the recirculation pump 98 and/or activate or disable any of the aforementioned inlets via the gas replenishment system. In one embodiment, the wastewater treatment system 1 0 economically maintains the desirable dissolved oxygen levels in the tank 96 via a series of pumps attached to a plurality of gas replenishment systems, each using different gases or gas blends as needed. The controller 102 activates
the gas entrainment systems that infuse the purified wastewater with concentrated blends of oxygen to economically regulate the dissolved oxygen demand increases from the microorganisms during high oxygen demand periods. The controller 1 02 deactivates the various oxygen systems as oxygen demands dwindle. The controller 1 02 may favor systems that use compressed atmospheric air instead of using pure oxygen.
[Para 48] As shown in FIG. 6, the purified wastewater in the tank 96 may be re- circulated back into the liquid-oxygen mixer 20 by means of the re-circulation pump 98 and corresponding re-circulation line 1 00. The re-circulation pump 98 is a key mechanism in replenishing the oxygen supply within the purified wastewater stream. The re-circulation pump 98 ensures that the purified wastewater is able to be replenished with oxygen via the liquid-oxygen mixer 20. The liquid-oxygen mixer 20, via the cyclonic mixer 1 06, is responsible for the efficient particulate contact and dissolution of gases (oxygen) in the wastewater stream. The particle movement within the cyclonic mixer 106, as previously described, is important for efficient oxygenation of the purified wastewater stream. As was shown in FIGS. 9 and 10, the microorganisms move throughout the cyclonic mixer 1 06 with varying angular velocity and vertical velocity. This "in" to "out" movement mixes the gas bubbles with the water clusters throughout the cyclonic mixer 1 06. Centrifugal force then causes bubble breakup inside "hungry" water molecules having no dissolved gas. Such a process avoids a gradient of gas concentration buildup near the gas/water interface. Such gradients oppose further gas dissolution until gas molecules move to the water layers with no dissolved gas.
In other words, diffusion is slow. If other mixing devices with similar high energy (high liquid RPMs) are used, bubble coalescence occurs with subsequent loss of gas into the atmosphere. Bubble loss limits the maximum amount of gas economically dissolvable in the wastewater. In the liquid-oxygen mixer 20, oxygenation occurs within the cyclonic mixer 1 06 and the corresponding pressurized vessel 1 14. Gas not entrained with the purified wastewater stream bubbles up and forms part of the head space 1 20, for later oxygenation. Hence, no gas escapes and such gas that does bubble out from within the wastewater stream is effectively recaptured and reused.
[Para 49] Effective use of the "in" to "out" movement of the gas bubbles at high velocities significantly enhances destruction of the gradients. Such mixing also aims to remove gradients in concentration of the products of microbial metabolism. Acceleration within the cyclonic mixer 106 usually ranges from 25- 1 00 Cs during routine operation. Even though the residence time of the purified wastewater in the cyclonic mixer 106 is only a fraction of a second, the rapid acceleration of the bubbles (or any particulates) traverse the short distance across the cyclonic mixer 1 06 (typically 1 centimeter [cm] for a 1 5 cm diameter unit) in milliseconds. The small bubble size (large surface area), large bubble flux, and the kinetic paths of the bubbles through the cyclonic mixer 1 06 facilitate high rate gas transfer with small gas loss. This results in the excellent ability to remove volital organic species or to airate (oxygenate) water, if desired. [Para 50] It is well known to those skilled in the art that subsequently depressurizing supersaturated pressurized air produces small bubbles. Such
bubbles are, for instance, produced in the dissolved air floatation process and are as small as 20 microns. Although, technologies that use pressurized gases with mechanical impellor stirring do not result in similar efficiencies. Bubble breakup, gas dissolution, particle to particle collisions, particle to bubble to polymer collisions, polymer uncoiling, etc. are particular problems in other systems. [Para 51 ] FIG. 1 2 illustrates levels of entrainment obtained using a set of eight hydro-cyclone reactor heads 1 36a-l 36h illustrated in FIGS. 1 1 a-1 1 h. The hydro- cyclone reactor heads 1 36a-l 36h have various cyclone inlet aspect ratios as illustrated. These aspect ratios include 24:1 (FIG. 1 I a); 10:1 (FIG. 1 1 b); 6: 1 (FIG. l i e); 2.6: 1 (FIG. l i d); 1 : 1 (FIG. l i e); circular (FIG. H f); four small circles (FIG. 1 1 g); and a shower head arrangement (FIG. 1 1 h). FIG. 1 2 illustrates the dissolve oxygen content of water (in ppm) per vessel pressure (in psi) using the various hydro-cyclone reactor heads 1 36a-l 36h of FIGS. 1 1 a-1 1 h. The selection of the hydro-cyclone reactor head can dramatically affect the amount of dissolved oxygen entrained or otherwise introduced into the liquid. The vessel pressure is determined by the pressure of the liquid introduced into the liquid-oxygen mixer 20, the size of the inlet 92, and the diameter of the cyclonic mixer 1 06. The appropriate hydro-cyclone reactor head plate is selected with a known vessel pressure to obtain the desired level of dissolved oxygen content in the purified wastewater stream discharged from the liquid-oxygen mixer 20. [Para 52] The remaining inorganic ions or non-biodegradable organic materials remaining in the wastewater can be removed by membrane separations. Virtually all of the other contaminants have been removed at this point. Thus, the
membranes are less susceptible to failing or clogging. Accordingly, a decontaminated water discharge outlet 1 38 removes the substantially cleaned and decontaminated water from the tank 96.
[Para 53] Although various embodiments have been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.
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