Abstract:
The multistage aeration system includes a water jet tank system having a closed water tank that holds a pool of water and seals in air above the pool of water. A nozzle in the top portion includes air bleeder passages to allow an ambient air to flow through the nozzle and into the closed water tank. A water flow meter and a water pump circulate water from the closed water tank to outside the tank through the water flow meter and then through the nozzle. The nozzle entrains air through the bleeder passages into the water as the water passes through the nozzle, and forms a jet spray into the pool of water. An air flow meter valve and a closed water tank air outlet pipe extend from the closed water tank and connect the water jet tank system to a diffused aeration tank system with a series tank system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to aeration systems, and particularly to a multistage aeration system. 
         [0003]    2. Description of the Related Art 
         [0004]    Aeration is one of the processes that can be employed in various air-water contactors. For example, aeration processes can be implemented within aquariums, flotation systems, and for biological treatment in wastewater systems, among other examples. In wastewater systems, the process air can be introduced during the secondary stage, also referred to as the biological stage, using convectional technologies to increase the concentration of Dissolved Oxygen (DO). This DO concentration is usually increased to an amount of about  2 . 0  parts per million (ppm). The DO concentration is needed for the bacteria to breathe, and also to consume the organic compounds. 
         [0005]    Presently, diffused aeration is used to introduce air into the system under a relatively high pressure from the bottom of the basin, which is also referred to as a clarifier, through pores on a pipe network utilizing compressors. However, there can be drawbacks with this approach. For example, this type of technology is relatively costly because it involves an extra cost by operating air compressors to provide the pressurized gas/air. Other examples of aeration processes include mechanical aeration processes utilizing impellers and plunging liquid jet. However, there can be drawbacks with these approaches as well. 
         [0006]    Certain environmental problems, such as contamination of seawater by wastewater, can require efficient and immediate aeration. Seawater contamination can ultimately lead to oxygen depletion and can consequently destroy aquatic life; for example as seen in the fish kill phenomenon, unless dissolved oxygen is restored quickly. In this case an aeration technology is required to promote aeration phenomena and to increase the DO concentration into water immediately. 
         [0007]    Aerators can also be used to remove unwanted gases from the atmosphere and to dissolve them into water. However, most of the existing aerators can consume a lot of energy with limited aeration due to the use of compressors for diffused aeration and propellers for mechanical aeration. Hence all of these processes appear to be costly, not very efficient, and fixed, meaning that they are not portable. In addition, conventional aeration systems are recognized as being considerably burdensome in their maintenance and management. These issues have encouraged researchers to seek an alternative system that provides efficient oxygen transfer at a relatively lower cost. 
         [0008]    Thus, a multistage aeration system solving the aforementioned problems is desired. 
       SUMMARY OF THE INVENTION 
       [0009]    The multistage aeration system includes a water jet tank system having a closed water tank. The closed water tank has a bottom portion that holds a pool of water and a top portion that seals in air above the pool of water (the headspace). A nozzle is disposed in the top portion of the closed water tank. The nozzle has air bleeder passages allowing ambient air to flow through the nozzle and into the closed water tank. A headspace pressure sensor in the top portion of the closed water tank measures headspace pressure developed inside the closed water tank. The multistage aeration system further includes a water flow meter and a water pump circulating water from the bottom portion of the closed water tank to outside the tank through the water flow meter and then through the nozzle at the top portion of the closed water tank. The nozzle entrains air through the bleeder passages into the water as the water passes through the nozzle, and forms a jet spray into the pool of water in the bottom portion of the closed water tank in order to aerate the pool of water. The headspace pressure is developed in the top portion of the closed water tank when the closed water tank is partially filled with water. 
         [0010]    The multistage aeration system also includes a diffused aeration tank system that involves a plurality of tanks. An air flow meter valve and a closed water tank air outlet pipe extend from inside the top portion of the closed water tank through the air flow meter valve and connect the water jet tank system to the diffused aeration tank system. The closed water tank air outlet pipe has perforated portions extending along an inside portion of the plurality of tanks, the perforated portions being adapted for diffusion of air into the tanks in the diffused aeration tank system. Additional features of the multistage aeration system include the tank system having a plurality of closed tank units connected either in series or in parallel by the closed water tank air outlet pipe and at least one terminal tank unit that is an open tank unit. When headspace pressure in the water jet tank system exceeds a predetermined limit (due to excess gas that is not dissolved in the pool of water and would otherwise be unused), the air flow meter is opened to allow the unused gas in the headspace to flow through the plurality of tanks in the diffuse aeration system. 
         [0011]    These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a diagrammatic side view in section of a multistage aeration system according to the present invention. 
           [0013]      FIG. 2  is a diagrammatic side view in section of an alternative embodiment of a multistage aeration system according to the present invention. 
       
    
    
       [0014]    Similar reference characters denote corresponding features consistently throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    The multistage aeration system provides for an aeration technology that can be useful, handy and economically feasible. The multistage aeration system can be used for environmental problems that need relatively immediate and efficient treatment, such as contamination of seawater with wastewater, and the removal of harmful gases. The multistage aeration system uses only a single water pump, and the ambient air/gas is entrained by a circulating water jet that utilizes the single water pump, and then enters a closed/sealed container/tank. The entrained gas is broken into bubbles after an impingement between the water jet and the water pool occurs. 
         [0016]    The entrained gas/air builds up the headspace pressure above the water pool, and is measured by a pressure gauge. The trapped air above the water pool is released when the headspace pressure increases to reach a predetermined value to aerate separate tanks/containers connected in series/parallel as a diffused aeration or any other aeration process. In this way, oxygen efficiency can be increased to exceed oxygen efficiency achieved by an integrated aeration process. 
         [0017]    Referring to  FIG. 1 , the multistage aeration system  200  utilizes a simple single water pump  90  for aeration. Ambient air/gas  10  is entrained by a circulating water jet  40  induced by the water pump  90 . The circulating water jet  40  enters a sealed, airtight tank, illustrated as the closed water tank  50 . The entrained gas is broken into air bubbles  120  after impingement between the jet  40  and a receiving water pool  70  occurs. The entrained gas/air builds up headspace pressure in the headspace area  30  above the water pool  70 . The headspace pressure in the headspace area  30  can be measured by a pressure sensor  100 . Further, the trapped air above the water pool  70  is released when the headspace pressure increases to a predetermined value to aerate a separate tank/container by diffused aeration (or other aeration process), shown as a tank system  150  having a plurality of tanks connected in series, although it will be understood that the aeration tanks in the tank system  150  may be configured in parallel, if desired. 
         [0018]    The multistage aeration system  200  includes two different systems, a water jet tank system  104  and a diffused aeration tank system  105 . Both systems  104  and  105  are connected together to establish a pressurized air from the water pump  90 . The water jet tank system  104  includes the closed water tank  50 , which has a bottom portion  52  disposed on a platform and a top portion  54 . In the top portion  54  of the closed water tank  50 , a downward spraying jet  40  of water having air entrained in the jet is introduced through the top portion  54 . The water pump  90  includes an inlet and an outlet, the inlet extending from the inside bottom portion  52  of the closed water tank  50 . 
         [0019]    The pump  90  causes water to flow from the closed water tank  50  through an outlet circuit of the water pump  90 . The outlet circuit of the water pump  90  includes a water flow meter  110 . The outlet circuit of the water pump  90 , via the water flow meter  110  and conduit, feeds into a connected nozzle  60  that enters the top portion  54  of the closed water tank  50 . As illustrated, the nozzle  60  has air bleeder passages  20 . Ambient air/gas  10  flows through the bleeder passages  20  and is entrained in the flow of water from the water pump  90  so that the nozzle  60  can cause a downward projecting water jet  40 . This downward projecting water jet  40  develops within and inside the closed water tank  50  of the water jet tank system  104 . 
         [0020]    As illustrated, the water from the downward projecting water jet  40  impinges the water in the water pool  70 , which serves as a receiving pool. During this impingement process, underwater air bubbles  80  are forced to the water surface of the water pool  70 , and are released as air bubbles  120 . As the pool of water  70  becomes increasingly saturated with oxygen from the air entrained in the jet  40 , the air bubbles  120  from unused air can accumulate in the headspace area  30  above the water pool  70  until a relatively sufficient pressure is built up inside the closed water tank  50 . The underwater air bubbles  80  penetrate to a certain depth in the water pool  70  and rise back up due to a bubble terminal velocity, i.e. buoyancy. 
         [0021]    Generally speaking, a gas is sparingly soluble in water, and hence relatively little oxygen, in case of aeration, is transferred to the surrounding liquid, depending on operational variables of the multistage aeration system  200 . The unused/remaining gas leaves the water pool  70  and is trapped in the headspace area  30 . The unused/remaining/undissolved gas leaves the water pool  70  to be trapped in the headspace  30  to reuse the remaining unused gas coming from the closed tank system  104 . This can allow for an increased chance, i.e. a detention or retention time, for the air to contact a liquid, i.e., by aeration to increase the process efficiency, and hence save money 
         [0022]    As mentioned previously, a pressure sensor  100  measures pressure inside the closed water tank  50 . An outlet pipe  140  extends from inside the top portion  54  of the closed water tank  50  of the water jet tank system  104 . As illustrated, the outlet pipe  140  flows through an airflow meter valve  130  and also includes a perforated portion, or a plurality of spaced apart perforated portions defining a diffuser pipe. The outlet pipe  140  extends to the second component of the multistage aeration system  200 , which is a diffuser aeration tank system  105 . Thus, the outlet pipe  140  connects the two components of the multistage aeration system  200 , connecting the water jet tank system  104  and the diffused aeration tank system  105  together. 
         [0023]    The diffused aeration tank system  105  includes a tank system  150 , and as shown in  FIG. 1 , the outlet pipe  140  is positioned within the tank system  150 . More specifically, the perforated portions of the outlet pipe  140  are positioned within pools of water in the aeration tanks of the tank system  150 . The perforated portions are adapted for diffusion of air/gas into the aeration tanks of the tank system  150  in order to aerate the water in the tanks. 
         [0024]    The tank system  150  has a plurality of stages of closed/sealed tanks connected in series/parallel. More specifically, a plurality of closed tank units  146  can be connected in series or in parallel to make up the tank system  150 . Depending on the user&#39;s needs, the initial number “i” of closed tank units  146  can be  1 , and can be increased to any number “n” that the user believes is suitable for their aeration needs. 
         [0025]    As shown, the outlet pipe  140  and the perforated portions of the outlet pipe are positioned within each closed tank unit  146 . If need be, additional pumps can be used to forward the air/gas from the one closed tank unit  146  to the next closed tank unit  146 . The closed tank units  146  can continue to be added, thus increasing the “n” number, until the user is satisfied. The final closed tank unit  146  will then be connected to an open tank unit  148 , as illustrated. Therefore, the relationship between the closed tank units  146  and the open tank unit  148  of the series tank system  150 , and the DO concentration that results, can be represented by the following functions below: 
         [0000]      DO T =Σ i   n DO i , i=1,2,3, . . . , n,   (1)
 
         [0000]    and therefore, 
         [0000]      DO T =DO 1 +DO 2 +DO 3 + . . . +DO n ,   (2)
 
         [0000]    where the amount of oxygen dissolved in each tank is DO 1 , i refers to the closed tank unit number, and DO T  is the total dissolved oxygen of the entire system. 
         [0026]    The unused gas coming from the water jet tank system  104  enters the tank system  150  through the air flow meter valve  130  and perforated pipe  140  to form the multistage aeration system  200 . The air flow meter valve  130  may be opened manually when the headspace pressure in the water jet tank system  104  reaches the predetermined value, or the air flow meter valve  130  may be a solenoid valve that is actuated by a microcontroller upon receiving a sensor signal from the pressure sensor  100 . 
         [0027]    Referring to  FIG. 2 , a multistage aeration system  500 , similar to the multistage aeration system  200 , is shown. Whereas  FIG. 1  essentially shows a batch reactor,  FIG. 2  shows a continuous flow reactor. The multistage aeration system  500  includes the same structures and features as described in the multistage aeration system  200 , such as a water jet tank system  104  and a diffused aeration tank system  105 , water pump  90 , ambient air/gas  10 , circulating water jet  40 , and closed water tank  50 , among other features and structures. However, the multistage aeration system  500  includes additional structures, as shown in  FIG. 2 , in addition to the structures found in multistage aeration system  200 . 
         [0028]    The additional structures of the multistage aeration system  500  can allow for delivery of continuous raw liquid streams, such as untreated water, into the multistage aeration system  500  at various points in the process. For example, raw liquid inlets  210  can allow for a raw liquid, such as untreated water, to be continuously added to the multistage aeration system  500  for treatment. The raw liquid inlets  210  can be added on either or both sides of the closed tank  50 . The raw liquid inlets  210  can include valves to control the flow of raw liquid. Therefore, there is a continuous influent and effluent flow into and out of the multistage aeration system  500  of raw liquid, as shown by a raw liquid inlet  210  entering the closed tank  50 , and another raw liquid inlet  210  delivering raw liquid at another point in the process. 
         [0029]    The closed tank  50  now includes a raw liquid outlet  220  that allows the raw liquid to exit the closed tank  50 . The raw liquid outlet  220  carries the raw liquid to a pump  230  so that the raw liquid can be delivered to the diffused aeration tank system  105 . As shown in  FIG. 2 , the raw liquid exiting from the closed tank  50  is further mixed with additional raw liquid by another raw liquid inlet  210 . Therefore, the liquid that arrives to the diffused aeration tank system  105  includes further raw liquid for treatment. The raw liquid is then distributed across the diffused aeration tank system  105 , i.e., throughout the tank system  150 . As shown in  FIG. 2 , the raw liquid is carried throughout the tank system  150  by a series of pipes  240  that connect the individual closed tank units  146  to one another to allow for communication between the tank units  146 . Thus, raw liquid can be distributed into each closed tank unit  146  of the tank system  150 . Therefore, the raw liquid is carried all the way to the individual tank units  146  for treatment and continuous flow of fresh raw liquid to replace the treated liquid in each tank unit  146  so that the multistage aeration system  500  continuously treats raw liquid. Thus, the multistage aeration system  500  receives raw liquid and dispenses treated liquid. 
         [0030]    It should be noted that the raw liquid inlets  210  can be placed anywhere within the multistage aeration system  500  to allow for the treatment of the raw liquid. For example, a pair of raw liquid inlets  210  can both be placed after the closed water tank  50 , such as after the pump  230 . Further, the multistage aeration system  500  validates the oxygen equations (DOT) (1) and (2) described above. 
         [0031]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.