WO2001049404A1

WO2001049404A1 - Wastewater oxygenation system

Info

Publication number: WO2001049404A1
Application number: PCT/US2001/000136
Authority: WO
Inventors: David G. Long; Klaus E. T. Siebert
Original assignee: Fbc Technologies, Inc.
Priority date: 2000-01-06
Filing date: 2001-01-02
Publication date: 2001-07-12
Also published as: WO2001049404A9; AU2756001A

Abstract

This invention relates to the oxygenation of wastewater to enhance the performance of aerobic wastewater treatment systems. An accelerator (5, 18, 25) produces a high velocity flow of wastewater (6, 27) in the presence of oxygen. The high velocity flow of wastewater (6, 27) is then directed toward an obstruction (14, 19, 26). When the wastewater impinges on the obstruction (14, 19, 26) the water becomes finely divided producing a fine mist. By dividing the flow of wastewater into fine droplets, this system not only increases the dissolved oxygen content of the water, but may also break down solid organic waste particles in the water.

Description

WASTEWATER OXYGENATION SYSTEM

Technical Field

Oxygenation of wastewater to enhance performance of aerobic wastewater treatment systems.

Background of the Invention

Many wastewater treatment systems use colonies of cultivated strains of microorganisms to decompose organic wastes. For instance, in U.S. Patent Nos. 4,670,149 (Francis) and 4,680,111 (Ueda), bacterial incubators are floated or suspended near, or just below, the surface of the water being treated. Because the coloηies used to treat wastewater require oxygen, it is necessary to aerate or oxygenate the wastewater being treated to sustain the colonies. Moreover, because many industrial sites have large bodies of wastewater, e.g. ponds, lagoons, etc., industries have a need for aeration systems that can effectively oxygenate large volumes of wastewater. Despite this need, industries have been largely unsuccessful in developing cost-effective aeration systems that meet their oxygenation needs.

Conventional oxygenation systems can include a wide variety of devices designed to increase dissolved oxygen content in water. Wastewater treatment engineers have discovered that aeration devices that produce very fine bubbles are particularly well-suited for oxygenating wastewater. Examples of such devices are disclosed in U.S. Patent Nos. 3,490,752 (Danjes et al.), 3,664,647 (Snow), and 4,215,082 (Danel). Other well-known aeration devices designed for use in larger bodies of water aerate wastewater by agitation. These devices use paddle-wheels, pumps and water jets. For example, U.S. Patent No. 4,072,612 (Daniel) discloses a large mixing pump, while U.S. Patent No. 3,984,323 (Evens) and French Patent No. 1 ,377,571 disclose water-jet mixers. Although these systems can effectively oxygenate relatively small volumes of wastewater, it becomes far too costly for industries to oxygenate large volumes of wastewater using these systems. Large volumes of wastewater are particularly common at food processing plants, pulp and paper facilities, chemical and textile companies and municipal wastewater treatment plants. Because it is extremely costly to oxygenate large volumes of water using conventional aeration systems, there is an urgent need for more efficient wastewater oxygenation systems.

Summary of the Invention

We have developed an economical wastewater oxygenation system that out-performs existing aeration systems and enhances the performance of aerobic wastewater treatment systems. Our system finely divides wastewater, thereby increasing dissolved oxygen content in the water. In addition to increasing the oxygen content of the water, our system may also simultaneously break down suspended solid waste into smaller particles that are easier to degrade. The system accelerates wastewater and produces a high velocity flow or stream in the presence of oxygen and then directs that flow or stream against an obstruction. When the wastewater smashes into the obstruction, the water divides into fine droplets forming a mist or spray, thereby increasing the amount of dissolved oxygen in the water. The oxygenated wastewater is then collected and pumped, or otherwise conveyed, back into a pond or lagoon for treatment.

By finely dividing wastewater in the presence of oxygen, our system can oxygenate water to levels that cannot be achieved using more costly, conventional aeration systems. Moreover, by oxygenating the wastewater and simultaneously breaking down solid organic waste particles in the water, our system can greatly enhance the efficiency of aerobic wastewater treatment systems. Brief Description of the Drawings

FIG. 1 is a schematic view of one embodiment of the instant invention wherein the accelerator is a centrifuge and the obstruction is an encircling containment wall.

FIG. 2 is a schematic view of one embodiment of the instant invention wherein the accelerator includes a pump and nozzle arrangement and the obstruction is a solid surface.

FIG. 3 is a schematic view of one embodiment of the instant invention wherein the accelerator includes a pump and nozzle arrangement and the obstruction is a perforated surface.

FIG. 4 is a schematic view of one alternative embodiment of the instant invention with a dual head sprinkler-style nozzle.

Detailed Description of the Invention

We have developed a high-efficiency, economical wastewater oxygenation system. Our system increases the dissolved oxygen content of the wastewater to enhance the performance of aerobic wastewater treatment systems. Moreover, our system can further enhance system performance by simultaneously breaking down solid organic waste into smaller particles that are easier to degrade.

Our system accelerates wastewater and produces a high velocity flow or stream directed toward an obstruction in the presence of oxygen. When the water impinges on the obstruction, the water divides into fine droplets, thereby increasing the surface area of the water and the amount of dissolved oxygen within it.

In its simplest form, our system includes an accelerator to generate the high velocity flow or stream and an obstruction positioned so that the flow or stream of wastewater generated by the accelerator impinges against the obstruction.

The accelerator can include several different devices capable of producing a high velocity flow. We have found that a centrifuge (depicted in FIG. 1 ) is an effective wastewater accelerator. Other accelerators such as pump and nozzle arrangements (depicted in FIGS. 2, 3 and 4) may also be effective accelerators. In addition, the obstruction can be any object, that when appropriately positioned can obstruct a high velocity flow or stream of wastewater impinging against it. Although we have found that solid surfaces are suitable obstructions, perforated surfaces may also provide adequate obstruction.

A first embodiment of the invention is shown in FIG. 1. The embodiment 10 of FIG. 1 uses a centrifuge 5 to accelerate wastewater 6. In this embodiment, wastewater 6 is delivered by a conduit 7 through an opening in the top of the centrifuge 5. The water 6 flows from the conduit 7 into a rotating, perforated basket 8 of the centrifuge 5. After the water 6 has entered the basket 8, the rotation of the basket 8 causes the water 6 to be forced out through the perforations of the basket 8 in a radial direction at high velocity. The basket 8 is rotated by a central drive shaft 9. Although various drive mechanisms can be used, in this embodiment, the shaft 9 is driven by a pulley 11 and belts 12, driven by a motor or actuator 13.

A containment wall 14 encircles the centrifuge basket 8 to obstruct the radial flow of wastewater 6 leaving the basket 8. After the wastewater 6 leaves the basket 8 it smashes against the interior of the containment wall 14. Although the containment wall 14 depicted in FIG. 1 has a solid surface, a perforated containment wall can also be used to obstruct the radial flow of wastewater 6. When impingement occurs, the wastewater 6 becomes finely divided and forms a spray or mist. When the wastewater 6 settles it is collected and conveyed by a conduit 15 to a lagoon or pond (not shown) for treatment. To ensure that the system 10 functions properly, we make the distance D between the bottom of the basket 8 and the bottom of the containment wall 14 large enough to permit the collected wastewater 6 to drain from the centrifuge 5 without flooding the containment area. As long as the oxygenated wastewater 6 drains relatively soon after it Has been collected, the basket 8 can rotate without interference from the collected wastewater 6. An alternative embodiment of our system is depicted in FIG. 2. This embodiment 20 includes a pump 16 connected to a hose 17 and nozzle 18. Wastewater 6 is pumped through the hose 17 out through the nozzle 18 producing a high velocity flow in the presence of oxygen. The flow of wastewater 6 leaves the nozzle 18 and impinges against an obstruction 19. In the embodiment of FIG. 2, the obstruction 19 has a solid surface. When the wastewater 6 impinges against the surface of the obstruction 19 the water 6 divides and produces a fine mist or spray. The mist or spray is then collected and conveyed through a conduit 21 back into a wastewater pond or lagoon (not shown) for treatment.

FIG. 3 depicts an embodiment that is nearly identical to the system of FIG. 2. System 20 depicted in FIG. 3, however, includes an obstruction 19 with a perforated surface. In this embodiment, as the stream of wastewater 6 smashes into the obstruction 19 the water 6 passes through the perforations of the obstruction 19 and becomes finely divided. The finely divided spray of wastewater 6 is then collected and conveyed by a conduit 21 back to a wastewater pond or lagoon (not shown) for treatment. In this embodiment, because water 6 may be present on both sides of the obstruction 19 following impingement, water 6 is collected from both sides of the obstruction 19 and rapidly drained so that the collection area does not flood.

The centrifuge embodiment of FIG. 1 differs from the pump and nozzle embodiments of FIGS. 2 and 3 in that a subsequent flow of wastewater generated by the centrifuge impinges on the surface of the obstruction at a region spaced apart from a region where a previous flow impinged. In the embodiments of FIGS. 1 and 2, both subsequent and previous flows of wastewater impinge on the same region of the surface of the obstruction. Theoretically, a more violent impingement may occur when the flow of wastewater impinges against a region on the surface of the obstruction that is relatively dry as compared with a region wetted from the impingement of a previous stream. Since a more violent impingement may divide the wastewater into finer droplets and increase surface area and dissolved oxygen content, it is possible that embodiments of our system that direct a subsequent flow to impinge on a region of the obstruction that is spaced apart from a region where a previous flow impinged will be more effective than embodiments that simply direct the flow of wastewater to impinge on the same region of the obstruction.

Although the systems of FIGS. 1 , 2, and 3 are preferred embodiments of our invention, other alternative embodiments may be equally effective. One alternative embodiment 28 appears in FIG. 4. In this embodiment an alternative pump and nozzle arrangement 29 is used to accelerate the wastewater 27. The pump and nozzle arrangement 29 in this embodiment includes a sprinkler-style nozzle 24. As water is pumped to the dual headed nozzle 24, the nozzle 24 rotates forming two high velocity radial streams of wastewater 27. As in the embodiment of FIG. 3, the embodiment of FIG. 4 includes a containment wall 26 that encircles the accelerator and obstructs the radial flow of wastewater.

Because the embodiment of FIG. 4 produces radial flows of wastewater 27 that impinge on the interior surface of the containment wall 26 at regions that are spaced apart from regions of previous flow impingement, this embodiment, like the centrifuge embodiment of FIG. 3, may be more effective than the stationary pump and nozzle arrangement embodiments of FIGS. 1 and 2.

Alternative arrangements of the embodiment of FIG. 4 are also possible. One possibility is to construct the embodiment 28 of FIG. 4 so that the containment wall 26 rotates around the dual headed nozzle 24 while the nozzle 24 remains stationary. Yet another possibility is to design the embodiment of FIG. 4 so that the nozzle 24 rotates in one direction while the containment wall 26 simultaneously rotates in an opposite direction.

Regardless of the particular arrangement selected, our system offers industries an improved, economical alternative to more costly conventional wastewater oxygenation systems. Our system produces higher dissolved oxygen content than existing systems and may simultaneously break down solid organic waste particles to further enhance the performance of aerobic wastewater treatment systems.

Claims

We Claim:

1 . A wastewater oxygenation system comprising: a. an accelerator that generates a high velocity flow of wastewater in the presence of oxygen; and b. an obstruction positioned so that the flow of wastewater impinges against the obstruction, causing the wastewater to be finely divided resulting in an increase in dissolved oxygen in the wastewater.

2. The system of claim 1 , wherein the accelerator includes a pump and a nozzle.

3. The system of claim 1 , wherein the accelerator is a centrifuge that generates the high velocity flow of wastewater in a radial direction toward the obstruction.

4. The system of claim 3, wherein the obstruction is a containment wall that encircles the centrifuge so that the flow of wastewater impinges on the containment wall.

5. The system of claim 1 , wherein the obstruction is a solid surface.

6. The system of claim 1 , wherein the obstruction is a perforated surface.

7. The system of claim 1 , wherein oxygen flows with the wastewater as the wastewater travels between the accelerator and the obstruction.

8. The system of claim 1 , including a mover that generates relative movement between the accelerator and the obstruction so that a subsequent flow of water is directed to impinge on a region on a surface of the obstruction that is spaced from a region on the surface of the obstruction where a previous flow made contact.

9. A wastewater oxygenating method comprising: a. accelerating a flow of wastewater to a high velocity in the presence of oxygen; and b. directing the flow of wastewater to impinge against an obstruction so that the water becomes finely divided resulting in increased dissolved oxygen content in the water.

10. The method of claim 9, including using a pump and a nozzle to accelerate the flow of wastewater.

1 1 . The method of claim 9, including using a centrifuge to accelerate the flow of wastewater.

12. The method of claim 11 , including positioning a containment wall around the centrifuge so that the flow of wastewater impinges against the containment wall.

13. The method of claim 9, including using a solid surface as the obstruction.

14. The method of claim 9, including using a perforated surface as the obstruction.

15. The method of claim 9, including flowing oxygen with the wastewater so that the dissolved oxygen content of the wastewater is increased as the water travels between and accelerator and the obstruction.

16. The method of claim 9, including generating relative movement between the accelerator and the obstruction so that a subsequent flow of wastewater impinges on the obstruction at a region on a surface of the obstruction that is spaced from a region on the surface of the obstruction where a previous flow made contact.

17. A wastewater oxygenator comprising: a. a centrifuge that accelerates wastewater in the presence of oxygen and produces a high velocity stream of wastewater directed in a radial direction against an impingement wall; and b. the impingement wall encircling the centrifuge so that the radial flow of wastewater impinges against the wall causing the wastewater to be finely divided, thereby increasing dissolved oxygen content of the water.

18. The oxygenator of claim 17, wherein the impingement wall has a solid surface.

19. The oxygenator of claim 17, wherein the impingement wall has a perforated surface.

20. The oxygenator of claim 17, wherein the impingement wall is fixed relative to the centrifuge.

21 . The oxygenator of claim 17, wherein the impingement wall moves in relation to the centrifuge.

22. A wastewater oxygenator comprising: a. an accelerator that produces a high velocity flow of wastewater in the presence of oxygen; b. an obstruction positioned so that the flow of wastewater produced by the accelerator impinges on the obstruction causing the wastewater to become finely divided, thereby increasing dissolved oxygen content in the water; and c. a mover that generates relative movement between the accelerator and the obstruction so that a subsequent flow of wastewater from the accelerator impinges on an area of a surface of the obstruction that is spaced from an area of the surface of the obstruction where a previous flow impinged.

23. The oxygenator of claim 22, wherein the accelerator include a pump and nozzle assembly.

24. The oxygenator of claim 22, wherein the accelerator is a centrifuge that produces the high velocity radial flow of wastewater against the obstruction.

25. The oxygenator of claim 24, wherein the obstruction is a containment wall that encircles a revolving basket of the centrifuge so that the radial flow of wastewater impinges against the interior surface of the containment wall.

26. The oxygenator of claim 22, wherein the mover moves the accelerator relative to the obstruction so that the subsequent flow of wastewater impinges on the surface of the obstruction at an area that is spaced from an area on the surface of the obstruction where the previous flow impinged.

27. The oxygenator of claim 22, wherein the mover moves the obstruction relative to the accelerator so that the flow of wastewater produced by the accelerator impinges against the obstruction at an area spaced from an area on the surface of the obstruction where the previous flow impinged.

28. The oxygenator of claim 22, wherein the mover moves both the accelerator and the obstruction relative to each other so that the subsequent flow of wastewater impinges on an area on the surface of the obstruction that is spaced from an area on the surface of the obstruction where the previous flow impinged.