WO2003066535A1

WO2003066535A1 - Method and system for controlling a biological reactor unit

Info

Publication number: WO2003066535A1
Application number: PCT/US2002/003968
Authority: WO
Inventors: Lorne Karl
Original assignee: Lorne Karl
Priority date: 2002-02-07
Filing date: 2002-02-07
Publication date: 2003-08-14
Also published as: AU2002255526A1

Abstract

A bio-reactor system (10) including a hydraulic air compressor (28) is set forth which includes the supply of data to a system controller (312) to control the parameters of the system for optimizing chosen outputs and performance of the system for aerobic treatment of fluid or production of compressed air to provide combustion air to a fuel fired turbine. The system controller (312) may be monitored and controlled remotely though wired or wireless communication.

Description

METHOD AND SYSTEM FOR CONTROLLING A

BIOLOGICAL REACTOR UNIT

Field of the Invention The present invention relates to hydraulic air compressors, systems employing hydraulic air compressors and systems and methods for aerobic, biological treatment of waste water. More particularly it relates to systems and method for controlling such hydraulic compressor/biological reactor systems and methods. Background

Compression of air using an hydraulic air compressor (HAC) is generally known. In Richardson, U.S. Patent 4,797,563, the disclosure of which is hereby incorporated by reference, discloses a HAC to compress air which is provided to the burners of a turbine to generate electrical power. According to this reference, air is drawn into the down shaft through open pipes into the flowing water to be compressed. The compressed air and water emerge from the shaft at a tunnel where the compressed air liberates from the water and is conducted to a turbine. Richardson does not show any means to forcible entrain air or for efficiently entraining air into the flowing liquid for compression thereof.

In Angle, U.S. Patent 5,099,648, a HAC is also disclosed which, similarly to Richardson '563 does not provide any means to forcibly entrain air into the liquid for compression thereof.

Accordingly, a drawback of the type of systems discussed above is that the volume of air for compression relies upon a configuration to naturally draw air into the liquid flow as the volume of air to be compressed. Means are not disclosed to increase the volume of air to be compressed to provide for more versatility and efficiency in a HAC or system incorporated the same. Still further, these systems provide no convenient means to control either or both of the flow of liquid through the HAC or the volume of compressed air produced. It would be desirable to provide means to control the flow of liquid and the volume of air produced by the HAC.

Still further, these prior HACs are subject to slug flow in their down shafts which can result in blowback of compressed air up the down shaft. The systems described above also provide no means to aerobically treat effluence such as waste water, sewage effluent or the like.

It would be desirable to provide a more versatile and efficient HAC to compress air for any purpose such as to provide combustion air to a burner or a fuel-fired turbine for the production of steam, work or electricity. It would also be desirable to provide a system incorporating a HAC to provide compressed air according to the foregoing which also uses and aerobically treats waste water such as sewage effluent or the like.

Regarding treatment of waste, it has been known in the prior art to treat effluent such as domestic and industrial waste through aeration to reduce the biologic oxygen demand (BOD) imposed by bio-degradation of the waste on the environment. For treatment of sewage it has been known to provide large surface area sludge ponds, aerators, sprinklers and bubblers to supply the BOD for bio-degradation of the waste. It has also been known to provide vertical shaft bio-reactors as described in Pollock, U.S. Patent No. 5,660,724. In vertical shaft bio-reactors, the effluent is supplied at the top of a vertical shaft to flow downwardly to the bottom. At the bottom of the vertical shaft, air may be injected. From the bottom a riser returns the effluent for re-circulation. Air is injected at the bottom of the riser to not only aerate the effluent but to create an air lift for circulation of the effluent. These systems aerobically treat the effluent but do not provide any byproduct such as compressed air which can be utilized to produce energy or work. Further injection of air at the bottom of the vertical shaft cannot provide for any significant compression thereof.

It would be highly desirable if a system could be devised which could not only aerobically treat and agitate a waste water effluent but which could also produce a byproduct of compressed air which can be utilized to, for example, supply combustion air to a burner or a turbine. Further it would be desirable to provide for a control system and method to control and optimize desired features of the system.

In my U.S. Patent 6,272,839 titled "Hydraulic Air Compressor and Biological Reactor System and Method" I described a system and method for compressing air for the production of electricity as well as bor bio- reacting waste. However, there is a need for a control system and method by which one or more of desired parameters of the system can be monitored, controlled and optimized and such features can be applied locally or remotely.

Summary of the Invention It is an object of the present invention to provide an improved bio- reactor system and control and method incorporating a hydraulic air compressor (HAC) which can be controlled to aerobically treat effluent and/or produce compressed air to fulfill a demand such as combustion air for a gas turbine.

There is, therefore, provided according to the present invention a more versatile and efficient bio-reactor system and method for compression of large volumes of air by which air and water flow volumes can be adjusted and a system and method incorporating such a HAC which also is adapted to aerobically treat waste water such as sewage effluent and the like.

Toward this end, a bio-reactor unit for aerobically treating fluid waste and for supplying compressed air to a demand is set forth which includes a source of liquid to be aerobically treated such as municipal waste sewage and a hydraulic air compressor having a liquid inlet, a liquid outlet and a compressed air discharge. The hydraulic air compressor (HAC) provides a head through which liquid falls to compress air in the liquid. A flow controller is provided to control the supply of liquid to the HAC liquid inlet, the liquid flowing through the HAC and from said liquid outlet producing compressed air discharged through said compressed air discharge. A level sensor is provided proximate the liquid outlet to maintain a liquid seal for the HAC. A compressed air sensor senses the flow of compressed air from the HAC. A controller controls the flow controller and control valve to regulate the level of liquid at said liquid outlet, flow of compressed air and flow rate through the HAC. By controlling flow, the supply of compressed air can be controlled as well as, if required or desired, the rate at which the liquid may be aerobically treated. Other features of the system and method include, but are not limited to, pumps with motor controllers to circulate the liquid through the bio- reactor and control the flow rate, a blower to inject air at the inlet of the HAC for compression thereof and a controller for the blower as well as a process control computer processor to monitor and control the various operational parameters of the system. The process control may be controlled by a wired or wireless wide area network (WAN), local area Network (LAN) or through the Internet as well.

The compressed air demand may be, for example, the compression air inlet of a fuel-fired turbine, burner or for any other purpose.

As can be appreciated, a system and method according to the present invention can be controlled to supply the compressed air demand at the rate required or to efficiently aerobically treat liquid effluent or a combination of both. The compressed air can be delivered to a fuel-fired turbine the output shaft of which can be used to provide work such as by driving an electric generator for the production of electricity. Thus effluent which would normally have to be separately aerobically treated through bubbling ponds or spray is aerobically treated advantageously in a HAC which produces compressed air for efficient operation of a turbine to produce electricity.

Further it should be understood that the system and method of the present invention can have numerous commercial applications such as purifying water for a commercial fish or prawn farm as well as generating electricity for plant use or sale to an electrical grid. Brief Description of the Drawings These and other features and advantages will become appreciated as the same becomes better understood with reference to description, claims and drawings wherein:

Fig. 1 illustrates a system using a hydraulic air compressor; Fig. 2 illustrates a portion of the system of Fig. 1 showing the injection of air for compression thereof by the hydraulic air compressor;

Fig. 3A is a side view of the air separator of the system of Fig. 1 ; Fig. 3B is a top plan view of the separator of the system of Fig. 1 ; Fig. 4 illustrates a system employing a further embodiment of the hydraulic air compressor according to the present invention;

Fig. 5 illustrates a system employing a alternate embodiment of the hydraulic air compressor according to the present invention; Fig. 6 illustrates an open system; Fig. 7 illustrates a closed system; Fig. 8 illustrates a further embodiment of the system and method;

FIG. 9 illustrates the system and method according to the present invention;

FIG. 10 illustrates a throat to assist in injection of air into the liquid; and FIG. 11 a system 400 according to the present invention for a fish farming pond.

Description Turning to Fig. 1 a system 10 according to the present invention is shown. The system 10 includes a source of liquid shown as a waste water post-treatment facility 12 which may be of conventional construction. The post-treatment facility 12 includes a chemical treatment pond 14 which may include nitrogen and phosphorous removal as well as chlorination or de- chlorination. A flotation tank 16 which may be of conventional construction receives treated waste water from the hydraulic air compressor (HAC) as hereinafter described. The floatation tank 16 communicates with an activated sludge pond 18 which is generally open and includes a pond lining 20 to isolate the activated sludge contained in pond 18 from the environment. Primary effluent at the post-treatment facility 12 enters the floatation tank 16 from the sludge pond 18 where buoyant materials float to the surface and are removed, the liquid is directed to the chemical treatment pond 14 for final treatment before released to the environment. Sludge which settles at the bottom or rises to the top of the floatation tank 16 is removed by a line 22 a portion of which is directed by line 24 to waste drying beds and a portion is mixed with water at a mixer 26 and returned to the activated sludge pond 18. The effluent contained in the activated sludge pond 18 is liquid and, according to the prior art is circulated and aerated by spraying, by bubbling or the like, for aerobic biological treatment of the sludge.

The system 10 according the present invention also includes a hydraulic air compressor or HAC 28 including a substantially vertical down shaft 30 having an upper end 32 and a lower end 34. The down shaft 30 may be embodied as a pipe extending into the ground to place its lower end 34 below the groundwater table 36 as shown in Fig. 1. The down shaft 30 is tapered, decreasing in diameter at least in a portion along its length from the upper end 32 to the lower end 34 to accelerate the flow of liquid there through and resist the formation of slug flow and blowback of compressed air produced in the manner described below. At the lower end 34, the down shaft 30 is communication with a separation chamber 38 as shown in Figs. 3A and 3B. The separation chamber 38 preferably extends horizontally from the down shaft

30 and may include a round, square or elliptical cross sectional configuration. At the lower end 34, the down shaft 30 is coupled to the separation chamber 38 at a first trap 40 adapted to be filled with liquid to maintain a seal between the lower end 34 and air chamber defined within the separation chamber 38 as hereinafter described. Preferably the separation chamber 38 has a larger cross section area than that of the down shaft 30 so that the liquid flowing there through is slowed to provide a period of time for compressed air to be released from the liquid for collection thereof. As shown in Fig. 3A, preferably a water level 42 is maintained within the separation chamber 38 above the first trap 40 to provide the aforementioned seal.

At the upper portion of the separation chamber 38 there is defined an air chamber 44 into which the air compressed by the HAC 28 is collected. The air chamber 44 may extend along the entire length of the separation chamber 38 and, as shown in Fig. 3A, may have a cross section aica which is semi-circular and reduces from a location proximate the first trap 40 along the length of the separation chamber 38. Thus, at the entrance to separation chamber 38 where a larger volume of compressed air is released, a greater cross section area is provided than at the opposite end where lesser amounts would be released. Opposite the first trap 40, the separation chamber 38 has a second trap 46 which, like the first trap 40, is adapted to remain filled with water to seal the air chamber 44 within the separation chamber 38. The second trap 46 is coupled to a return riser 48 extending substantially vertically to return the liquid, as shown in Fig. 1 , to the sludge pond 18. Thus it can be appreciated that liquid introduced at the upper end 32 of the down shaft 30 of the HAC 28 flows through the down shaft 30 to collect at and submerge the first trap 40 for compression of air carried with the liquid. The liquid enters the separation chamber 38 whereat compressed air is released from the liquid into the air chamber 44. The liquid flows through the separation chamber 38 to the second trap 46 whereupon it enters the riser 48 for return to the sludge pond 18. As stated above, preferably the separation chamber 38 has a larger cross section than does the down shaft 30 to slow the flow of liquid for release of compressed air. Compressed air collected in the air chamber 44 is directed by an air line

50 for purposes of which will hereinafter be explained.

To prevent flooding of the separation chamber 38, level sensing means are provided to sense the level of liquid in the separation chamber 38.

As is known, waste water retained in the sludge pond 18 is preferably aerobically treated by aeration. This aeration, according to the prior art, is done with sprinklers, bubblers and large surface areas of sludge ponds 18. The sprinklers, bubblers and large surface area heretofore used is replaced by the apparatus of the present invention. Aeration is attained by operation of the HAC.

With reference to Fig. 2, to increase the efficiency of the HAC 28 and for aerobic treatment of the liquid circulating through the HAC 28, means are provided for forcibly introducing air into the liquid preferably proximate the upper end 32. These means introduce air at a positive pressure (a pressure above atmospheric pressure) to not only aerate the liquid and act as a biological reactor therefor, but also to increase the volume of air to be compressed by the HAC 28.

Accordingly, at the upper end 32 of the down shaft 30, there is provided a support structure 52 through which extends the down shaft 30 into the ground. Proximate the upper end 32 there is provided a restriction 54 defining a narrow throat 56 adapted to increase the velocity (and reduce the pressure) of the liquid entering the upper end 32 of the down shaft 30. Proximate the exit of the throat 56 and at a location proximate the location where the liquid is at an elevated velocity, there is disposed one or more injectors 58 for injecting air into the liquid. The injectors 58 may be embodied as a single pipe extending axially into the down shaft 30 or may be embodied as a bundle of pipes disposed axially in the down shaft 30 to introduce smaller diameter streams of air injected into the liquid. The injectors 58 communicate with a blower 60 which is adapted to deliver air through the injectors 58 into the liquid. By adjusting the volume air delivered by the blower 60, the volume of air introduced into the liquid entering the HAC 28 can likewise be adjusted. As can be appreciated, greater amounts of air can be introduced to the liquid as it enters the HAC 28 than could be naturally entrained or drawn in by a simple venturi arrangement or like arrangement. Furthermore, by providing the blower 60, a control can be provided on the amount of air injected into the liquid. It should further be understood that the air injected into the liquid acts to aerobically treat the liquid which is mixed as it flows down the down shaft 30 to the separation chamber

30.

With reference to Fig.1 , the system 10 includes means for supplying liquid to the HAC 28 for compression of air. These means may be from a water source 62 such as a lake, dam or river introduced into the HAC 28 through a water supply line 64 and/or delivered by pumps 66 delivering liquid from the sludge pond 18. The pumps 66 have a discharge line 68 which is in communication with the upper end 32 of the HAC 28. Thus an elevated source 62 or pumps 66 may be used to supply water or waste water or a combination thereof to the HAC 28. The liquid is delivered to the upper end 32 of the down shaft 30 whereupon it flows due to gravity to compress the air entrained and carried by the liquid, the compressed air and liquid delivered to the separation chamber 38 for separation of the air from the liquid.

To control the flow of the air contained within the air chamber 44, the HAC 28 includes means to control the flow of liquid through the separation chamber 38. As is known, the vertical column of liquid flowing up the riser 48 exerts a pressure head at the separation chamber 38. Preferably the control means of the present invention includes a control valve 70 disposed in the riser 48 which can be adjusted to control the flow of liquid flowing upwardly through the riser 48. Thus, it can be understood, that by altering either or both the rate of supply of liquid to the down shaft 30 or the restriction provided by the control valve 70, the air and water flow in the air chamber 44 can be adjusted. Further by adjusting the amount of air delivered by the blower 60, the volume of air compressed by the HAC can further be adjusted. It is to be understood that the control valve 70 will operate between selected parameters so as not to back up the flow in the down shaft 30 and/or flood the separation chamber 38. Thus the control valve 70 can be used to tune the system 10 in conjunction with the rate at which liquid is supplied to the HAC 28 and the rate at which air is delivered by the blower 60.

The liquid returning through the riser 48 is discharged back into the sludge pond 18. As can be appreciated, the liquid at the sludge pond 18 is circulated through the HAC 28 for aerobic treatment and mixing. Thus the system 10 accomplished several desired ends. First, ;!: provides a means to aerobically treat waste water such as sludge by forcibly introducing air into the liquid and acting as a bioreactor therefor. Second, it enhances oxygenation by the mixing action as it flows through the system. Further it creates a source of compressed air.

As further can be appreciated, the volume of air compressed by the HAC 28 can further be adjusted by increasing the volume of air injected by the blower 60 through the injectors 58 into the liquid. Thus it is to be understood, that the HAC 28 of the system 10 can have varied outputs based on flow volumes and depending upon the adjustment of the control valve 70 and blower 60. Thus the HAC 28 can be adjusted to optimize the desired output.

To prevent over pressurization of the separation chamber 38 and loss of the seals provided by the first and second traps 40, 46 , a relief tube 200 extends from an end submerged in the separation chamber 38 to vent for example above ground, in the event that pressure builds in the separation chamber 38 to such a level as to lower the water level 42 so as to approach the loss of the seals at the first and second traps 40, 46, the end of the tube 200 would be exposed and the compressed air in the separation chamber 38 would vent reducing pressure and returning the water level so as to maintain the seals.

In the event the level sensing means sense a rise in the liquid level in the separation chamber, the air line 50 may be closed or the flow of compressed air restricted to build pressure in the air chamber 38 to lower the liquid level. Turning to Figure 4, a alternate embodiment of the invention is shown.

Like components bear like reference numerals.

The system 10 of Figure 4 includes a modified HAC 28' which does not

include a horizontally or substantially horizontally disposed separation chamber 38. According to this embodiment, the down shaft 30 extends into a separation

chamber 38' which includes an inner bell 72 and an outer bell 74. The outer

bell 74 is closed having a bottom 76 including an impingement block 78 defining an impingement surface 80 against which the liquid flowing through the down shaft 30 impinges as it falls from the open lower end 34 of the down shaft 30. The infringement surface 80 is generally cup-shaped having a central cone 82 to angularly deflect the flowing liquid into the impingement surface 80. Upon engaging the impingement surface 80 the liquid flowing from the down shaft 30 releases and breaks up the compressed air bubbles carried therewith into the inner bell 72 for collection thereof. As shown in Fig. 4, the bottom of the inner bell 72 is open and remains submerged below the water level 84 maintained within the outer bell 74. Level sensors 85 in the inner bell 72 sense the level of liquid to maintain the inner bell 72 submerged and to prevent flooding of the inner bell 72. The liquid discharged into the inner bell 72 collects and circulates from the inner bell 72 into the outer bell 74 whereupon it is carried upwardly through the outer bell 74 to an outlet 86 for return to the sludge pond 18. Compressed air collected in the inner bell 72 is removed by an air line 50 from the inner bell 72.

As can be appreciated the system 10 according to Fig. 4 may also include the restriction 54, blower 60 and injectors 58 as described above to increase the volume of air compressed by the HAC 28. By controlling the air flow to the inner bell 72 and volume of air introduced by the blower 60, the HAC 28 can be balanced to produce a desired air and water volume within the limits defined by the physical constraints of the construction of the HAC 28. Preferably the impingement block 78 or at least the surface 80 thereof is made of a wear resistant material such as steel, concrete or the like to resist wear induced by the impinging liquid. Turning to Figure 5 a further embodiment of the invention is shown. Like components bear like reference numerals. The upper end 32 of the down shaft 30 terminates and is open to the sludge pond 18. A screen 150 may be provided in the sludge pond 18 to screen large materials from entering the upper end and an inlet gate 152 may be provided to terminate the flow from the pond 18 into the upper end 32. Liquid from the sludge pond 18 enters the upper end and falls, in the manner described above with reference to Fig. 1 to the first trap 40 and separation chamber 38. From the separation chamber 38 the liquid flows up the riser 48 through the control valve 70 and into a subterranean pumping chamber 154 located at an elevation below the upper end 32 of the down shaft 30 equal to the desired head for the HAC 28. The pumps 66 are located in the pumping chamber 154 pump the liquid through a pipe 156 to return to the sludge pond 18. The return water flow in the riser

48 flows into the horizontally disposed pumping chamber 154 where it is sucked into the pumps 66 and pumped back to the sludge pond 18. The control value 70 is located below the pumping chamber 154.

A liquor/water mixer 158 may be provided in the sludge pond 18 to dilute the liquor in the sludge pond 18.

The embodiment of Fig. 5 is adapted to reduce above ground structures which may not be considered aesthetically pleasing.

As can be appreciated the HAC 28 according to Figure 5 may also include the restriction 54, blower 60 and injectors 58 as described above to increase the volume of air compressed by the HAC 28. Turning to Figs. 6 through 8, the operation of the system 10 to produce electricity is shown. With reference to Fig. 6, the waste water effluent is passed through a screen 88 to screen particulate matter before the effluent is discharged into the sludge pond 18. From the sludge pond 18 the liquid effluent is pumped by pumps 66 into the HAC 28 to produce compressed air.

The compressed air is removed from the HAC 28, and more particularly the separation chamber 38, and is delivered to means for producing work, be it power, combustion or the like. As shown in Fig. 6, these means may include a fueled gas turbine 90 coupled to an electrical generator 92 for the production of electricity. While the compressed air from the HAC 28 may be delivered directly to the burners for the turbine 90, as shown in Fig. 5 the compressed air may be preconditioned. Accordingly, a heat exchanger or recuperator 94 and humidifier 96 may be provided. Exhaust heat from the turbine 90 is passed through the recuperator 94 to preheat the air prior delivery to the turbine 90. The humidifier 96 humidifies the heated air to increase its density for more efficient operation of the turbine 90. In that the compressed air from the HAC 28 is dry air, humidifying the air may be desirable. The use of the this air for electrical generation is significantly improved with the addition of a humidifier 96. With continued reference to Fig. 6, the liquid circulated through the HAC

28 is returned to the sludge pond 18 for recirculation and treatment as described above. Water from the sludge pond 18 is also delivered to the floatation tank 16 and from there to the chemical treatment pond 14 for ultimate discharge of treated effluent as described above.

Thus it can be appreciated, that when the system 10 is included in an overall system including means for generating power, the recirculation of the liquid not only provides for biological reaction of the effluent through aerobic treatment but also provides compressed, combustion air to a turbine 90 operating a generator 92 for the production of electrical power.

Turning to Fig. 7, a modified system is shown which uses a closed loop recirculation system for driving the HAC 28. According to the embodiment of Fig. 6, a recirculation pond or sludge pond 18 is proviαed to store liquid such as water for operating the HAC 28. The liquid is pumped by pumps 66 to the HAC 28 for generation of electrical power as described above with reference to Fig. 6. From the HAC 28 the water is continuously recirculated to the sludge pond 18. If desired, like the embodiment in Fig. 6, the electrical power generated by the generator 92 may be used to power the pumps 66.

With reference to Fig. 8, a combined open and closed system is shown. Like components carry like reference numerals. Liquid is brought into an impoundment structure 100 to act as a reservoir for supply of liquid by pumps 66 to the HAC 28. The compressed air generated by the HAC 28 is supplied to the turbine 90 for generation of electrical power in the manner described above.

Again the electrical power created by the generator 92 may be used to power the pumps 66. The liquid discharged from the HAC 28 is directed to a recirculation or sludge pond 18 providing a source of water to be pumped by

pumps 66' likewise to the HAC 28.

Thus liquid is supplied to the HAC 28 from either or both the impoundment structure 100 (such as a water supply like a dam) and a recirculation or sludge pond 18.

As further can be appreciated, the HAC 28 may be, with reference to Fig. 1 , driven directly from a water source 62 such as a dam or river, with the water returned by the HAC 28 discharged below the dam or the like. Thus the HAC 28 according to the present invention need not only be used in a system including biological reaction as described with reference to Fig. 1.

With reference to FIG. 9, the method and system according to the present invention is illustrated in connection with a HAC according to FIG. 4. It should be understood that the system and method of the present invention could also be incorporated into the various arrangements of the HACs discussed above.

The system 300 includes a hydraulic air compressor (HAC) 302 having and inlet 304 which may be embodied as a receiving tank 306 which feeds the shaft 308 of the HAC 302. Liquid fed into the tank 306 at the inlet 304 flows down the shaft 308 to the separation chamber 310 located vertically below the inlet 304 to impart kinetic energy to liquid falling down the shaft 308 to the separation chamber 310.

The separation chamber 310 has an inner bell 72 and outer bell 74. The outer bell 74 is closed having a bottom 76 including an impingement block 78 defining an impingement surface 80 against which the liquid flowing through the down shaft 30 impinges as it falls from the open lower end 34 of the down shaft 30. The impingement surface 80 is generally cup-shaped having a central cone 82 to angularly deflect the flowing liquid into the impingement surface 80. Upon engaging the impingement surface 80 the liquid flowing from the down shaft 80 releases and breaks up the compressed air bubbles carried therewith into the inner bell 72 for collection thereof. The bottom of the inner bell 72 is open and remains submerged below the liquid level maintained within the outer bell 74. Level sensors 85 in the inner bell 72 sense the level of liquid to maintain the inner bell 72 submerged. The sensors 85 issue signals corresponding to the liquid level in the inner bell 72 to a process controller 312 including a computer terminal 314. Air pressure in the inner bell 74 prevents flooding thereof.

The liquid discharged into the inner bell 72 collects and circulates from the inner bell 72 into the outer bell 74 whereupon it is carried upwardly through the outer bell 74 to an outlet 86. From the outlet 86 the liquid is directed into a pumping chamber 316 for return circulation to the inlet 304 or discharge from the system to, for example, post treatment as by chlorination. The pumping station 316 may be subterranean depending upon the configuration of the HAC 304. Compressed air collected in the inner bell 72 is removed by an air line 50 from the inner bell 72.

To control the flow and back pressure imposed at the separation chamber 310, the outlet 86 includes a control valve 70 in communication with the process controller 312. A flow meter 318 measures the rate of liquid flow from the outlet 86 to the pumping chamber 316 and issues signals to the processor 312.

To circulate liquid, which may be municipal, sewage waste, at least one variable speed pump 66 is disposed in the pumping chamber 316. Each pump 66 has a variable speed motor controller 320 in communication with the process controller to control the circulation rate of the liquid. The pumps 66 have a discharge line 322 which discharges back to the HAC inlet 304. A pressure gauge 324 and flow meter 326 in communication with the process control measure the pressure and flow rate of liquid through the discharge line 322. The pumps 66 can also discharge from the system to further process the liquid such as by chlorination, biological treatment or the like before discharge to the environment.

Where the system 300 is used in conjunction with aerobic treatment of municipal waste, there may be a settling pond 328 where solid materials are settled out of the liquid and removed as sludge. The lighter liquid effluent is discharged from the settling pond 328 to a holding pond 330 to serve as the inventory of liquid for treatment. Any solid material sludges which settle in the holding pond are removed. The liquid from the holding pond is sent to the pumping chamber 316 for circulation through the HAC 302. As an alternative to the system 300 shown, the discharge 86 may discharge into the holding pond

330 and from there to the pumping chamber 316. At 332 make-up liquid, e.g., water, may be added to the pumping chamber 316 for start-up and to make-up any deficiency of liquid to be treated. By circulating the liquid through the HAC 300 and back to the holding pond 330, a closed system may be defined for aerobically treating the effluent. Liquid is circulated though the HAC where it is aerated and mixed through the processes of compressing air, falling through the shaft 308 and impinging the impingement block 78. By knowing the volume (V) of liquid to be aerobically treated (the volume in the HAC 300 and holding pond 330) and the circulation rate (flow rate as detected by flow meter 326), an aerobic treatment time T can be determined. That is, the time T necessary to adequately treat the effluent volume V, given its constituency, may be calculated. After the determined treatment time T has been satisfied, the volume may be discharged for further treatment if desired.

To increase the aerobic treatment and volume of air to be compressed the system may also include a blower or fan 60 may be provided to inject air into the fluid entering the inlet 304. A pressure gauge 332 and flow meter 334 measure the pressure and flow of the injected air. A manifold 336 may assist in the introduction and mixing of injected air into the liquid. A variable speed motor controller 337 drives the fan 60 and is in communication with the controller 312.

Disposed in the compressed air line 50 is a demister unit 338 adapted and configured to remove entrained liquid for the air line 50. The demister unit

338 may be embodied as a plurality of demister pads installed at the air line 50 discharge from the separation chamber 310. A pressure gauge 340, flow meter 342 and temperature gauge 344 are disposed in the air line to determine pressure and volume flow rate. These gauges and meters, 340, 342 and 344 are in communication with the controller 312. The compressed air is supplied to a demand therefore such as injection air for an engine or, as shown, combustion air for a gas turbine unit 90. For the turbine 90, the compressed air may be passed through a recuperator 94 before being supplied to the turbine, fuel supplied, burners 346. While the drawing suggests a gas fired turbine, it should be understood that the demand for compressed air could be for an internal combustion engine providing work, steam boiler combustion air or any other demand. Further the fuel can be propane, natural gas, a liquid fuel, coal, hydrogen or other combustible fuels. It should be noted that where the liquid contains methane or other combustible gases (such as liquid sewer waste), the compressed air from the HAC may include combustible gases decreasing the demand for outside fuel. The expansion of gases by combustion are directed though the turbine to produce work such as driving an electrical generator 92. The exhaust gases from the turbine are sent to atmosphere and/or directed to the recuperator 94 to pre-heat the combustion air. Temperature gauges 348, 350 sense the temperature of the exhaust gases before and after the recuperator 94 and send signals to the controller 312. A power gauge 352 senses the power being produced by the generator 92. Where the generator 92 is to power the pumps 66, a start-up compressor 354 having a motor control 356 is provided. Once the system 300 is sustaining, the compressor 354 may be shut-down. The process controller 312 monitors and controls the various aspects of the system. The various pump motor controls 320, fan motor control 60 as well as the sensors and gauges referenced above and shown in FIG. 9 send data to and are controlled by the controller 312. This data and control signals may be sent by wired or wireless communication techniques. Further, the controller

312 may be accessed and the performance of the system 300 monitored and controlled by wired, wireless may be controller 312 may be accessed by wireless, wired (LAN, WAN, Internet), cable or satellite data transmission means. The system 300 can be controlled by the process controller 312 to optimize one or several outputs. For example, if the liquid does not require aerobic treatment or very little aerobic treatment and the amount of compressed air produced is to be maximized, as for operating the turbine T to maximize the power output, the controller 312 would control the fan 60 motor control to inject the maximum amount of air into the liquid and the pump motor controls 320 would operate at a speed to maximize the circulation rate of the liquid. If the liquid is such that maximum aerobic treatment is required and the supply of compressed air is an ancillary benefit, the controller 312 would operate the pump motor controls 320 to reduce the liquid circulation rate to maximize the time the liquid remains in the system 300 as well as the fan 60 motor control to inject air for aerobic treatment of the fluid. Make-up air compressor 354 motor control 356 can be operated to provide additional combustion air to the turbine T. Turning to FIG. 10, a further embodiment of the throat 56 disposed in the shaft 308 which is adapted to increase the velocity (and reduce the pressure) of the liquid entering the inlet 304. Proximate the exit of the throat 56 and at a location proximate the location where the liquid is at an elevated velocity, there is disposed one or more injectors 58 for injecting air into the liquid. The injectors 58 may be embodied as a single pipe extending axially into the down shaft 30 or may be embodied as a bundle of pipes disposed axially in the down shaft 30 to introduce smaller diameter streams of air injected into the liquid. The injectors 58 communicate with a blower or fan 60 which is adapted to deliver air through the injectors 58 into the liquid.

With continuing reference to FIG. 10, disposed downstream from the injectors 58 and proximate the exit of the throat 56 additional injectors 400 are included to inject air into the liquid. The flow of liquid, the velocity of which is increased by the throat, entrains and carries the injected air for compression and for aeration of the liquid. If desired at 402 biological or chemical treatment may be added such as by adding biological agents to assist in purifying sewer waste water.

Turning to FIG. 11 , the system 500 is shown for use in conjunction with a fish farm. The fish pond 502 contains water and the fish being raised. Liquid from the fish pond 502 is circulated by a pump 504 (or the liquid may flow freely to as through a gate) to a HAC 302 where the air is aerated (oxygenated) and agitated by passing through the HAC 302. Pump 66 returns the liquid to the fish pond 502. The liquid, prior to return to the fish pond 502 may be filtered or treated as by injecting ozone (0₃ ) at 504 , treating the liquid with ultraviolet light at 506 or heating or chilling the liquid at 508 to maintain the desired temperature of the pond 302. The compressed air produced by the HAC may be used to further oxygenate the pond 502 as by bubbling air and/or supply compressed air as combustion air to a fuel fired turbine T. A generator 92 coupled to the turbine T generates electricity which can be transferred, e.g. sold, to the local electrical grid or used to operate plant pumps, chillers and other electπcal equipment. The exhaust from the turbine T is used to operate a heater for the liquid and/or recuperator (not shown in FIG. 11). While I have shown and described certain embodiments of the present invention, it is to be understood that it is subject to many modifications and changes not departing from the spirit and scope of the appended claims.

Claims

I Claim:

1. A bio-reactor unit for aerobically treating fluid waste and for supplying compressed air to a demand therefore, said unit comprising: a source of liquid to be aerobically treated; a hydraulic air compressor having a liquid inlet, a liquid outlet and a compressed air discharge; a flow controller to control the supply of liquid to the liquid inlet, said liquid flowing through the air compressor and from said liquid outlet producing compressed air discharged through said compressed air discharge; a level sensor at said liquid outlet; a compressed air sensor to sense the flow of compressed air from said compressed air discharge; and a controller to control said flow controller and control valve to regulate the level of liquid at said liquid outlet, flow of compressed air and flow rate through said air compressor.

2. The unit of claim 1 said flow controller including at least one motor driven pump and a motor controller to control the discharge flow rate of said pump.

3. The unit of claim 1 comprising said flow controller is a flow controlling weir.

4. The unit of claim 1 further comprising an air injector to inject air into the liquid at said liquid inlet for compression thereof and an injection controller to control the rate at which air is injected into said liquid.

5. The unit of claim 4 comprising said air sensor sending signals to said injection controller to control the rate at which compressed air is supplied to said demand.

6. The unit of claim 5 comprising said demand is a fueled gas turbine, said compressed air discharge in communication with said turbine burners, said turbine coupled to an electrical generator.

7. The unit of claim 4 comprising a central controller in communication with said injection controller, air sensor, injection controller, level sensor, flow controller and control valve to control liquid flow, level and air flow.

8. The unit of claim 7 comprising said liquid is effluent to be aerobically treated, said central controller configured to control the flow rate and residence time of the effluent in the unit.

9. The unit of claim 8 comprising said liquid outlet discharging into said source for re-circulation thereof through said unit, said central controller configured to control residence time of said effluent in said source and unit for aerobic treatment thereof.

10. The unit if claim 7 comprising said central controller including a controlling computer processor in communication with a remote terminal, said processor and remote terminal configured to provide for remote control of said unit.

11. The unit of claim 10 comprising said computer processor in communication with said terminal though an Internet connection.

12. A bio-reactor unit for aerobically treating fluid waste and for supplying compressed air to a demand therefore, said unit comprising: a source of liquid to be aerobically treated; a hydraulic air compressor having a liquid inlet, a liquid outlet and a compressed air discharge; a flow controller to control the supply of liquid to the liquid inlet, said liquid flowing through the air compressor and from said liquid outlet producing compressed air discharged through said compressed air discharge to said demand; a level sensor at said liquid outlet; a compressed air sensor to sense the flow of compressed air from said compressed air discharge; and a system controller to control said flow controller and control valve to regulate the level of liquid at said liquid outlet, flow of compressed air and flow rate through said air compressor.

13. The bio-reactor of claim 12 comprising an air injector to inject air with said supply of liquid for compression thereof by said air compressor and an injector controller to control the rate of injection of said air.

14. The bio-reactor of claim 13 comprising said air injector is a fan driven by a fan motor controlled by a motor controller in communication with said system controller to control the rate of injection of said air.

15. The bio-reactor of claim 12 comprising said source and said liquid in said air compressor defines a volume of liquid, said system controller configured to control the resident time of said liquid in said source and air compressor for aeration thereof.

16. The bio-rector of claim 12 comprising said demand is combustion air for a burner, said system controller configured to control the flow of liquid to satisfy said combustion air demand.

17. A method for aerobically treating liquid effluent and producing compressed air for a demand comprising: providing a hydraulic air compressor having an effluent inlet, outlet and a compressed air discharge; supplying effluent from a source defining a volume of effluent to the effluent inlet, said effluent falling through the air compressor to aerate the effluent and compress air, said compressed air discharged to said demand and said effluent discharged from said effluent outlet to said source; circulating the effluent from said source through said air compressor; controlling the rate of circulation and residence time in said source and air compressor for aerobic treatment of the effluent; and discharging a volume of aerobically treated effluent.

18. The method of claim 17 comprising injecting air at said effluent inlet for compression thereof and for aerobic treatment.

19. The method of claim 17 comprising directing the compressed air from said compressed air discharge as combustion air