Liquid purification or separation – Processes – Including geographic feature
Reexamination Certificate
1998-08-27
2001-09-18
Lithgow, Thomas M. (Department: 1724)
Liquid purification or separation
Processes
Including geographic feature
C210S170050, C210S220000, C261S077000, C261S123000
Reexamination Certificate
active
06290855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to water aeration and more specifically this invention relates to a device for aerating surface water.
2. Background of the Invention
Bodies of surface water, either manmade or naturally occurring, maintain their viability partly by their physical interaction with elements of the environment. Such interaction includes aeration and agitation caused by wind movement, fish and animal activity, seasonal inversions and in-rushing water from underground springs.
Oftentimes however, surface waters suffer eutrophic conditions due to low oxygen, high carbon dioxide levels. Eutrophic conditions occur for a number of reasons, including the existence of a high biological load whereby organisms use more oxygen and create more carbon dioxide than fauna create and utilize, respectively. Eutrophic waters also result from “still” water conditions wherein oxygenation is initially low due to shelter from wind, or due to a lack of water ingress or egress. Once a eutrophic condition establishes itself, an explosion of surface vegetation occurs, such as algae. With the algae comes an exacerbation of the problem inasmuch as air-exchange with the water surface is further inhibited, as is the penetration of oxygen-generating sunlight (via photosynthesis) to lower water depths.
Low oxygen conditions also can be caused by freezing of surface waters. In such situations, sunlight needed to drive oxygen-producing photosynthesis occurring in water fauna is reduced, as is aeration caused by surface winds. Winter kill of fish due to low dissolved oxygen (DO) levels is common, particularly in northern climes.
Also, treatment of organic waste in surface waters, such as what occurs in municipal sanitation systems, requires the introduction of appreciable amounts of oxygen. Without such oxygen injections, eutrophic conditions abound due to high biological load of degrading bacteria.
A myriad of methods for aerating surface waters have been utilized in efforts to eliminate or at least minimize low oxygen environs as described above. However, most of these methods utilize complex systems for mixing air and water. Typical of such systems are U.S. Pat. Nos. 4,906,363; 4,828,696; and 4,702,830, all granted to Makino et al. In such designs, air is pumped into a chamber designed to create intermittent bubbles of air encased in a tube (with the diameter of the tube being the same as that of the bubbles). As the bubbles rise to the water surface they push upwards water trapped in the tube above these bubbles.
U.S. Pat. No. 4,687,494 granted to Escobal discloses a system for water agitation that utilizes pumping of both water and air. Similarly, U.S. Pat. No. 4,522,151 granted to Arbisi discloses a device wherein fine bubbles of air are produced within a conduit through which the water is being pumped.
A water pump is utilized in U.S. Pat. No. 3,563,641 granted to Eron, wherein the pump is floating on the surface of the pond. Stream aerators also exist (e.g. U.S. Pat. No. 3,489,396 granted to D'Aragon) and are designed for high velocity fluid flow.
A common disadvantage inherent with many of the devices discussed above is that waste-laden water must traverse intricate pumps and other mechanisms and passageways to ultimately become aerated. These intricate structures are easily obstructed or fouled by icing or by waste carried by the water. The systems can be further damaged by suspended solids and even chemicals found in the water.
A need exists in the art for a simple device for aerating surface waters in all seasons. The device should be constructed with off-the-shelf componentry and be easily maintained, even in the most eutrophic conditions. The device should incorporate no intricate componentry with its design embodying few if any moving parts, turbines or gate valves.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a water pond aerator that overcomes the disadvantages of the prior art.
Another object of the present invention is to provide an aerator that does not require a water pump. A feature of the present invention is that water movement is effected by means of high-pressure air injected along the longitudinal axis of a conduit wherein water is allowed to flow. An advantage of the present invention is that the pump-less design provides a the low-maintenance system not prone to fouling or damage, even when water to be aerated contains high levels of suspended solids and vegetation.
Yet another object of the present invention is to provide an aerator which oxygenates water in a range of flow rates. A feature of the present invention is the formation of a column of water with the longitudinal axis of the column defining a core devoid of water. Another feature of the invention is that oxygenating fluid is injected into the column of water only from points within the core. An advantage of the invention is that water flows vertically upwards along the walls of a cylindrical conduit defining the shape of the column and as a result of the direction of application of the injected oxygenated fluid so that solely the velocity of the oxygenated fluid determines the rate of intake of water into the aeration device. Another advantage of the present invention is that the vertical wall of the conduit acts as a support for the upward flowing water, and therefore confers frictional interaction between the water and the device, thereby extending the residence time of the water in the oxygenation zone.
A further object of the present invention is to provide an aerator containing no moving parts. A feature of the invention is that a column of water, defined by the configuration of the aerator, is propelled upwardly by a longitudinally extending inner core of oxygenated fluid. An advantage of the invention is that water circulates through the aerator without confronting any moving obstructions.
Yet another object of the present invention is to provide an aerator that can be used at different depths of a fluid requiring oxygenation. A feature of the present invention is that it comprises detachable conduits whose length can be varied. An advantage of the present invention is that it can be used in many different bodies of water.
Another object of the present invention is to provide an aerator such that a multiplicity of replicas thereof can be deployed over the surface of a pond while utilizing but one shore-based power-driven unit. A feature of the present invention is that its functioning requires only high pressure air supplied by an external blower. An advantage of the present invention is that a single such shore-based unit may supply several aerators.
In brief, the invention provides an aeration device comprising a means for forming a column of water, wherein the column has a longitudinally-extending core devoid of water; and a means for contacting oxygen with the water.
The invention also provides an aerator for a body of water having a surface, said device comprising means for injecting high pressure air in said aerator in such a manner that water is made to flow continuously without recourse to a water pump.
Also provided is an aerator for a surface of a body of water comprising a conduit for confining water to a longitudinal passage way, said conduit having an axis, a first end, a second end and a region intermediate the first and second ends; means for injecting high pressure air in the intermediate region and along the axis of said conduit in such a manner that the air forms a longitudinally-extending air core coaxial to the passageway; and means to maintain the axis of the aerator in a substantially vertical orientation.
A method for aerating water is provided comprising forming a column of water wherein the column has a longitudinally extending core devoid of water; and injecting oxygenated fluid into the core so that the water is contacted with the oxygenated fluid only from points within the core.
REFERENCES:
patent: 2957495 (1960-10-01), Ashbrook
patent: 3446488 (1969-05-01), Mail
patent: 4169873 (1979-10-0
Cherskov & Flaynik
Lithgow Thomas M.
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