Methods and devices for performing reactions

Disclosed are devices suitable for performing chemical and/or biological reactions. Also disclosed are methods of simultaneously performing at least two chemical and/or biological reactions under different conditions in a single reaction chamber.

FIELD AND BACKGROUND OF THE INVENTION

The invention, in some embodiments, relates to the field of chemical and biological processes. In some embodiments, the invention relates to the field of wastewater processing. In some embodiments, the invention relates to the field of chemical reactors.

Chemical and biological processes are often performed in one or more vessels (reactors). Methods and devices suitable for performing chemical and biological processes are sought after.

For example, it is known to use microbial digestion to process wastewater. Methods and devices suitable for wastewater processing by microbial digestion that have advantages over known such methods and devices are sought after.

It is known to use Venturi pumps in the field of chemical and biological reactions, see for example, U.S. Pat. No. 4,193,950, Soviet patent application SU 956559-A1 and China utility model publication CN204672151-U.

SUMMARY OF THE INVENTION

Some embodiments of the invention herein provide methods and devices for performing chemical and biological reactions (e.g., chemical reactions, microbial digestion of wastewater) in a vessel. In some such embodiments, a vessel is provided that allows definition of two or more volumes inside the same chamber of such a vessel, where the reaction conditions of each such volume are independently controllable.

Thus, according to an aspect of some embodiments of the teachings herein, there is provided a device suitable for performing chemical and/or biological reactions, comprising:a. a vessel defining at least one reaction chamber configured for holding liquids, the chamber having an upper portion, a lower portion and a vertical axis (when in use);b. at least one chamber inlet providing fluid communication into the chamber from outside the chamber;c. at least one chamber outlet providing fluid communication from inside the chamber to outside the chamber;d. an upper mixing assembly located inside the chamber; ande. a lower mixing assembly located inside the chamber, positioned below the upper mixing assembly,
each mixing assembly comprising a Venturi pump having a motive fluid inlet, an aspirate inlet and a Venturi pump outlet, the Venturi pump configured for accepting liquid contents of a corresponding portion (upper or lower portion) of the chamber into the motive fluid inlet as motive fluid, and to expel fluid out through the Venturi pump outlet back into the corresponding portion of the chamber. The upper mixing assembly is thus configured when operated to allow circulation of liquid in the upper portion of the chamber without substantially circulating liquid in the lower portion of the chamber and the lower mixing assembly is thus configured when operated to allow circulation of liquid in the lower portion of the chamber without substantially circulating liquid in the upper portion of the chamber. Such configuration allows the definition of independently-controllable reaction conditions in the upper portion and in the lower portion of the chamber of the vessel, thereby allowing simultaneously performing at least two chemical and/or biological reactions (one reaction in the upper portion, the other reaction in the lower portion) under different conditions in the reaction chamber.

Typically, the reaction chamber is a single continuous volume inside the vessel with no substantial physical partition that defines a border between the upper portion and the lower portion of the chamber.

In some embodiments, when both the upper and lower mixing assembly are operated, there is an intervening portion in the chamber located between the upper portion and the lower portion in which fluid is not substantially circulated when the mixing assemblies are operated.

As discussed herein in greater detail, in some preferred embodiments, the upper mixing assembly and the lower mixing assembly are independently operable, e.g., allowing operation and/or control of the first mixing assembly independently of operation and/or control of the second mixing assembly.

In some embodiments, the chamber has a height greater than greatest width (e.g., diameter). In some such embodiments, the chamber is cylindrical. In some such embodiments, the chamber is prismatic. In some such embodiments, the chamber is substantially a cone. In some such embodiments, the chamber is a truncated cone.

In some embodiments, at least one chamber inlet provides fluid communication from outside the chamber to inside the upper portion of the chamber. Additionally or alternatively, in some embodiments, at least one chamber inlet provides fluid communication from outside the chamber to inside the lower portion of the chamber. In some embodiments, the device is provided with a second (or more) inlet that provides fluid communication from outside the chamber to inside the chamber. Multiple inlets allow addition of liquid for reaction into a specific portion of the chamber.

In some embodiments, at least one chamber outlet provides fluid communication from inside the lower portion of the chamber to outside the chamber.

In some embodiments, at least one chamber outlet provides fluid communication from inside the upper portion of the chamber to outside the chamber.

In some embodiments, at least one Venturi pump outlet is directed perpendicularly to the vertical axis of the chamber. In some such embodiments, all Venturi pump outlets of the device are directed perpendicularly to the vertical axis of the chamber. In some embodiments, at least one Venturi pump outlet is directed parallel to the vertical axis of the chamber, e.g., vertically upwards or vertically downwards. In some such embodiments, all Venturi pump outlets of the device are directed parallel to the vertical axis of the chamber.

In some embodiments, the Venturi pumps are immobile, that is to say, during operation remain in a fixed location inside the vessel.

In some embodiments, the device further comprises at least one liquid-driving pump functionally associated with the upper mixing assembly, the at least one liquid-driving pump configured to drive liquid contents of the chamber into a motive fluid inlet of a Venturi pump of the upper mixing assembly. In some embodiments, the liquid-driving pump functionally associated with the upper mixing assembly is an immersible liquid pump located inside the chamber. In some embodiments, at least one of the liquid-driving pumps functionally associated with the upper mixing assembly is not functionally associated with the lower mixing assembly thereby allowing operation of the upper mixing assembly independently of the lower mixing assembly by activation of that liquid-driving pump.

In some embodiments, the device comprises at least one liquid-driving pump functionally associated with the lower mixing assembly, the at least one liquid-driving pump configured to drive liquid contents of the chamber into a motive fluid inlet of a Venturi pump of the lower mixing assembly. In some embodiments, the liquid-driving pump functionally associated with the lower mixing assembly is an immersible liquid pump located inside the chamber. In some embodiments, at least one of the liquid-driving pumps functionally associated with the lower mixing assembly is not functionally associated with the upper mixing assembly thereby allowing operation of the lower mixing assembly independently of the upper mixing assembly by activation of that liquid-driving pump. In some embodiments where the device comprises at least one liquid-driving pump functionally associated with the upper mixing assembly, at least one of the at least one liquid-driving pump associated with the upper mixing assembly is also at least one of the at least one liquid-driving pump associated with the lower mixing assembly.

In some embodiments where the device comprises at least one liquid-driving pump functionally associated with the upper mixing assembly, the device further comprises a controllable valve having at least two states:an open state allowing flow of liquid from the liquid-driving pump to the motive fluid inlet of a Venturi pump of the lower mixing assembly; anda closed state preventing flow of liquid from the liquid-driving pump to the motive fluid inlet of the Venturi pump of the lower mixing assembly.
In some embodiments, such a controllable valve allows operation of the lower mixing assembly independently of the upper mixing assembly by selection of the state of the controllable valve.

In some embodiments, the device further comprises a controllable valve having at least two states:an open state allowing flow of liquid from the liquid-driving pump to the motive fluid inlet of the Venturi pump to the upper mixing assembly; anda closed state preventing flow of liquid from the liquid-driving pump to the motive fluid inlet of the Venturi pump to the upper mixing assembly.
In some embodiments, such a controllable valve allows operation of the upper mixing assembly independently of the lower mixing assembly by selection of the state of the controllable valve.

In some embodiments, at least one of the at least one liquid-driving pump associated with the upper mixing assembly is different from at least one of the at least one liquid-driving pump associated with the lower mixing assembly. In some such embodiments, each one of the two mixing assemblies has a set of dedicated liquid-driving pumps, that is to say, all of the liquid-driving pumps associated with the upper mixing assembly are different from all of the liquid driving pumps associated with the lower mixing assembly.

In some embodiments, at least one liquid-driving pump associated with the upper mixing assembly and at least one liquid-driving pump associated with the lower mixing assembly are separately operable (i.e., activatable). In some embodiments, such separately operability allows operation of the lower mixing assembly independently of the upper mixing assembly by operation of a liquid-driving pump associated only with the lower mixing assembly. In some embodiments, such separately operability allows operation of the upper mixing assembly independently of the lower mixing assembly by operation of a liquid-driving pump associated only with the upper mixing assembly.

In some embodiments, the liquid-driving pumps are electrically-powered pumps. In some such embodiments, an alternating current power supply to the pumps is functionally associated with a frequency converter, allowing to change the rate of pumping of the pumps.

In some embodiments, the device further comprises a gas line in fluid communication with an aspirate inlet of a Venturi pump of the upper mixing assembly. In some embodiments, the gas line provides fluid communication between an aspirate inlet of a Venturi pump of the upper mixing assembly and the open air. In some embodiments, the device further comprises a gas inlet valve functionally associated with the gas line, having at least two states:a closed state preventing flow of gas through the gas line to an aspirate inlet of a Venturi pump of the upper mixing assembly; andan open state allowing flow of gas through the gas line to an aspirate inlet of a Venturi pump of the upper mixing assembly.
In some embodiments, such a gas inlet valve allows allowing, preventing and/or regulating the inflow of gas into the upper portion of the chamber by selection of the appropriate valve state.

In some embodiments, the device further comprises a gas reagent reservoir in fluid communication with an aspirate inlet of a Venturi pump of the upper mixing assembly, in some embodiments a pressurized gas reagent reservoir, in some embodiments through a gas line as (e.g., as described above), in some embodiments through a valve (e.g., analogous or identical to the gas inlet valve described above).

In some embodiments, the device further comprises a liquid reagent reservoir in fluid communication with an aspirate inlet of a Venturi pump of the upper mixing assembly, in some embodiments through a liquid reagent line, in some embodiments through a valve having at least two states: a closed state preventing flow of liquid reagent from the liquid reagent reservoir through the liquid reagent line to an aspirate inlet of the Venturi pump of the upper mixing assembly; and an open state allowing flow of liquid reagent from the liquid reagent reservoir through the liquid reagent line to an aspirate inlet of the Venturi pump of the upper mixing assembly. In some embodiments, such a valve allows allowing, preventing and/or regulating the inflow of liquid reagent into the upper portion of the chamber by selection of the appropriate valve state.

In some embodiments, the device further comprises a liquid reagent reservoir in fluid communication with an aspirate inlet of a Venturi pump of the upper mixing assembly through a gas line as described above.

In some embodiments, the device further comprises a gas line in fluid communication with an aspirate inlet of a Venturi pump of the lower mixing assembly. In some embodiments, the gas line provides fluid communication between the aspirate inlet of the Venturi pump of the lower mixing assembly and the open air. In some embodiments, the device further comprises a gas inlet valve functionally associated with the gas line, having at least two states:a closed state preventing flow of gas through the gas line to an aspirate inlet of the Venturi pump of the lower mixing assembly; andan open state allowing flow of gas through the gas line to an aspirate inlet of the Venturi pump of the lower mixing assembly.
In some embodiments, such a gas inlet valve allows allowing, preventing and/or regulating the inflow of gas into the lower portion of the chamber by selection of the appropriate valve state.

In some embodiments, the device further comprises a gas reagent reservoir in fluid communication with an aspirate inlet of a Venturi pump of the lower mixing assembly, in some embodiments a pressurized gas reagent reservoir, in some embodiments through a gas line as (e.g., as described above, in some embodiments through a valve (e.g., analogous or identical to the gas inlet valve described above).

In some embodiments, the device further comprises a liquid reagent reservoir in fluid communication with an aspirate inlet of the Venturi pump of the lower mixing assembly, in some embodiments through a liquid reagent line, in some embodiments through a valve having at least two states: a closed state preventing flow of liquid reagent from the liquid reagent reservoir through the liquid reagent line to an aspirate inlet of the Venturi pump of the lower mixing assembly; and an open state allowing flow of liquid reagent from the liquid reagent reservoir through the liquid reagent line to an aspirate inlet of the Venturi pump of the lower mixing assembly. In some embodiments, such a valve allows allowing, preventing and/or regulating the inflow of liquid reagent into the lower portion of the chamber by selection of the appropriate valve state.

In some embodiments, the device further comprises a liquid reagent reservoir in fluid communication with an aspirate inlet of the Venturi pump of the lower mixing assembly through a gas line as described above.

In some embodiments, the device further comprises an upper temperature controller, located within or in immediate proximity (e.g., on the walls of the chamber) to the upper portion of the chamber to control the temperature of the liquid contents of the chamber located in proximity of the upper mixing assembly without substantially affecting the temperature of the contents of the chamber located in proximity of the lower mixing assembly. In some such embodiments, the upper temperature controller comprises a heating component, located within or in immediate proximity to the upper portion of the chamber to heat liquid contents of the chamber located in proximity of the upper mixing assembly without substantial heating of contents of the chamber located in proximity of the lower mixing assembly. In some such embodiments, the upper temperature controller comprises a cooling component, located within or in immediate proximity to the upper portion of the chamber to cool liquid contents of the chamber located in proximity of the upper mixing assembly without substantial cooling of contents of the chamber located in proximity of the lower mixing assembly. In some such embodiments, the upper temperature controller comprises both such a heating component and such a cooling component. In some embodiments, the device further comprises an upper heater as the temperature controller, located within or in immediate proximity to the upper portion of the chamber to heat liquid contents of the chamber located in proximity of the upper mixing assembly without substantial heating of contents of the chamber located in proximity of the lower mixing assembly.

In some embodiments, the upper temperature controller is configured to control the temperature of liquid contents of the chamber that are to exit a Venturi pump outlet of the upper mixing assembly, e.g., the heating or cooling is through the Venturi pump, the liquid-driving pump or a conduit therebetween.

In some embodiments, the device further comprises a lower temperature controller, located within or in immediate proximity (e.g., on the walls of the chamber) to the lower portion of the chamber to control the temperature of the liquid contents of the chamber located in proximity of the lower mixing assembly without substantially effecting the temperature of the contents of the chamber located in proximity of the upper mixing assembly. In some such embodiments, the lower temperature controller comprises a heating component, located within or in immediate proximity to the lower portion of the chamber to heat liquid contents of the chamber located in proximity of the lower mixing assembly without substantial heating of contents of the chamber located in proximity of the upper mixing assembly. In some such embodiments, the lower temperature controller comprises a cooling component, located within or in immediate proximity to the lower portion of the chamber to cool liquid contents of the chamber located in proximity of the lower mixing assembly without substantial cooling of contents of the chamber located in proximity of the upper mixing assembly. In some such embodiments, the lower temperature controller comprises both such a heating component and such a cooling component. In some embodiments, the device further comprises a lower heater as the temperature controller, located within or in immediate proximity to the lower portion of the chamber to heat liquid contents of the chamber located in proximity of the lower mixing assembly without substantial heating of contents of the chamber located in proximity of the upper mixing assembly.

In some embodiments, the lower temperature controller is configured to control the temperature of liquid contents of the chamber that are to exit a Venturi pump outlet of the lower mixing assembly, e.g., the heating or cooling is through the Venturi pump, the liquid-driving pump or a conduit therebetween.

According to an aspect of some embodiments of the invention, there is also provided a method of simultaneously performing at least two chemical and/or biological reactions under different conditions in a single reaction chamber, comprising:

placing a device as described herein so that the vertical axis of the device is at an angle within 45° of parallel to the gravity vector (as depicted in the Figures) so that the upper portion of the chamber is above the lower portion of the chamber (in some embodiments, immediately above);

placing at least one liquid inside the reaction chamber of the vessel so that both the upper portion and the lower portion contain a liquid; and

performing at least one of:operating the upper mixing assembly to circulate the liquid in the upper portion of the chamber without substantially circulating liquid in the lower portion of the chamber; andoperating the lower mixing assembly to circulate the liquid in the lower portion of the chamber without substantially circulating liquid in the upper portion of the chamber,thereby performing a first reaction (e.g., a chemical and/or biological reaction) in the upper portion of the reaction chamber and a second reaction (e.g., a chemical and/or biological reaction) in the lower portion of the reaction chamber, wherein conditions of the first reaction are different than the conditions of the second reaction.

In some embodiments, the angle is within 30°, within 25°, within 20°, within 15°, within 10° and even within 5° of parallel to the gravity vector.

In some embodiments, the liquid in the upper portion comprises a solvent with reagents. In some embodiments, the liquid in the upper portion comprises an organic solvent. In some embodiments, the liquid in the upper portion comprises an aqueous solvent. In some embodiments, the liquid in the upper portion is wastewater so that the solvent is water and the reagents are waste to be digested.

In some embodiments, the liquid in the lower portion comprises a solvent with reagents. In some embodiments, the liquid in the lower portion comprises an organic solvent. In some embodiments, the liquid in the lower portion comprises an aqueous solvent. In some embodiments, the liquid in the lower portion is wastewater so that the solvent is water and the reagents are waste to be digested.

In some embodiments, the liquid in the upper portion has a different gas content (e.g., oxygen content) than the liquid in the lower portion. For example, in some embodiments aerobic digestion of wastewater is performed in the upper portion of the chamber while anaerobic or anoxic digestion of wastewater is performed in the lower portion of the chamber.

In some embodiments, the liquid in the upper portion of the chamber has a different density than the liquid in the lower portion of the chamber.

In some embodiments, the first mixing assembly and the second mixing assembly are operated in a different manner, thereby leading to the different reaction conditions in the upper portion and the lower portion. In some embodiments, the different operation comprises at least one of:addition of a different liquid to one of the upper portion and the lower portion (in some embodiments through the respective mixing assemblies);addition of a different gas to one of the upper portion and the lower portion (in some embodiments through the respective mixing assemblies); andmaintaining a temperature in the upper portion different than a temperature in the lower portion.

Some embodiments of the invention herein provide methods and devices for processing wastewater using microbial digestion. Accordingly, in some embodiments, the at least one reaction chamber is a digestion chamber configured for holding wastewater and suitable for containing microbial digestion of wastewater as a reaction. In some such embodiments, the device further comprises a solid bacterial growth support inside at least part of the digestion chamber, in some embodiments, substantially all of the digestion chamber.

In some embodiments, phase-transfer reactions are performed in a device according to the teachings herein where the denser phase is located in the lower portion of the chamber around the lower mixing assembly, and the less dense phase is located in the upper portion of the chamber around the upper mixing assembly. In some such embodiments, the denser phase is aqueous and the less dense phase is organic (e.g., comprises a solvent having a density less than 1, such as oil or petrol ether). In some such embodiments, the less dense phase is aqueous and the denser phase is organic (e.g., comprises a solvent having a density greater than 1, such as dichloromethane). In some such embodiments, the denser phase is an aqueous solution of high density (e.g., concentrated brine) and the less dense phase is aqueous with a lower density.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. In case of conflict, the specification, including definitions, takes precedence.

As used herein, the terms “comprising”, “including”, “having” and grammatical variants thereof are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof. These terms encompass the terms “consisting of” and “consisting essentially of”.

As used herein, the indefinite articles “a” and “an” mean “at least one” or “one or more” unless the context clearly dictates otherwise.

As used herein, when a numerical value is preceded by the term “about”, the term “about” is intended to indicate +/−10%.

DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

Some embodiments of the invention herein provide methods and devices suitable for performing chemical and/or biological reactions, in some embodiments, processing wastewater using microbial digestion.

Specifically, some embodiments of the teachings herein provide methods and devices allowing simultaneously performing, in one vessel, chemical and/or biological reactions in liquid environments under two different conditions in two distinct and volumes of the vessel. In some such embodiments, the liquid environments in each of the distinct volumes are immiscible (e.g., organic and aqueous liquids). In some such embodiments, the liquid environments in each of the distinct volumes are miscible but have substantially different densities (e.g., brine and non-brine water). In some such embodiments, the liquid environments in each of the distinct volumes are miscible.

Specifically, some embodiments of the teachings herein provide methods and devices suitable for microbial digestion that include a vessel defining at least one chamber that allows performance of aerobic, anaerobic and anoxic modes of digestion of wastewater in one chamber, sequentially or simultaneously.

Some embodiments of the method and device obviate the need for multiple vessels to perform SBR (sequential bioreactor) digestion.

In some embodiments, the use of a single vessel saves space, resources (maintenance and energy), processing time, and is relatively simple to produce, factors that are extremely important in the field of environmentally-friendly wastewater processing.

Some embodiments allow use of preferred conditions for each mode of digestion, for example, by allowing selective heating and/or selective addition of reagents (e.g., bacteria, nutrients, pH modifiers, feedstock for increased production of desired gases, e.g. combustible biogases), for example, allowing greater generation of methane-forming bacteria by controlling the temperature and pH of anaerobic digestion.

Some embodiments allow anaerobic and anoxic modes of digestion to be performed without use of sealed vessels and/or scrubbers.

Embodiments of the teachings herein are suitable for processing various types of wastewater, including blackwater and agricultural manure slurry.

The principles, uses and implementations of the teachings of the invention may be better understood with reference to the accompanying description and figures. Upon perusal of the description and figures present herein, one skilled in the art is able to implement the teachings of the invention without undue effort or experimentation. In the figures, like reference numerals refer to like parts throughout.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth herein. The invention is capable of other embodiments or of being practiced or carried out in various ways. The phraseology and terminology employed herein are for descriptive purpose and should not be regarded as limiting.

An embodiment of a device according to the teachings herein, device10is schematically depicted in side cross section inFIG. 1. Device10is configured for processing of wastewater using microbial digestion.

Device10comprises a vessel12defining a reaction chamber14that is a digestion chamber configured for holding wastewater, chamber14, when in use, having an upper portion16a, a lower portion16band a vertical axis20. Chamber14is a cylinder with a height greater than diameter. A chamber inlet22provides fluid communication from outside chamber14to inside upper portion16aof chamber14, allowing addition of wastewater for processing into chamber14. A chamber outlet24provides fluid communication from inside chamber14to outside chamber14, allowing removal of water that has been sufficiently processed from upper portion16aof chamber14.

In some embodiments, at least part of chamber14(e.g., one or both of upper portion16aand lower portion16b) comprises a solid bacterial growth support (fixed growth media), allowing development of sessile microbes.

At the bottom of chamber14there is a converging (conical) sludge-accumulation portion26provided with a sludge valve28allowing removal of accumulated sludge from chamber14.

Passing coaxially through chamber14is a support bar30of stainless steel to which are secured an upper mixing assembly32awithin upper portion16aand a lower mixing assembly32bpositioned below upper mixing assembly32awithin lower portion16b.

Each one of mixing assemblies32aand32bcomprise four Venturi pumps (a total of eight Venturi pumps in device10), four of which are depicted inFIG. 1. InFIG. 1, one of the Venturi pumps of mixing assembly32ais labeled36aand one of the Venturi pumps of mixing assembly32bis labeled36b.

InFIG. 2, a Venturi pump36(identical to Venturi pumps36aand36b) is schematically depicted in side cross section, having a motive fluid inlet38, aspirate inlets40′ and40″ and a Venturi pump outlet42.

The Venturi pumps (e.g.,36aand36b) of device10are configured for accepting liquid contents of chamber14into motive fluid inlet38as motive fluid. As the moving motive fluid passes a Venturi nozzle41and out through Venturi pump outlet42, fluid (such as a gas or liquid) is drawn into aspirate inlets40′ and40″ in accordance with the Bernoulli principle to mix with the moving motive fluid.

In mixing assemblies32aand32b, Venturi pump outlets42of the Venturi pumps (e.g.,36aand36b) are directed downwardly parallel to vertical axis20of chamber14.

Each of mixing assemblies32aand32bfurther comprises an associated liquid-driving pump44aand44b, respectively, each pump44aand44bhaving an associated pump inlet46.

Each liquid-driving pump44aor44bis functionally associated with the four Venturi pumps of a respective mixing assembly32aor32b. Specifically, each one of liquid-driving pumps44aand44bis configured to draw liquid contents of a corresponding portion16aand16b(respectively) of chamber14into a respective pump inlet46and drive the drawn liquid through a conduit48into motive fluid inlets38of the associated Venturi pumps (e.g.,36aand36b).

Any suitable liquid-driving pumps may be used in implementing the teachings herein. In some embodiments, the liquid-driving pumps are immersible pumps. In some embodiments, the liquid driving pumps are electrically-powered. In some embodiments, electrically-powered liquid-driving pumps receive direct-current electrical power. In some such embodiments, the power supply of each liquid-driving pump is functionally associated with a variable resistor, allowing an operator to set the rate of pumping of each one of the liquid-driving pumps independently. In device10, liquid-driving pumps44are electrically-powered immersible pumps that receive alternating-current electrical power for operation by electrical cables (not depicted), the alternating current passing through a controllable frequency converter. Such configuration allows an operator to set the rate of pumping of each one of liquid-driving pumps44aand44bindependently without excess stress on pumps44.

Device10further comprises a gas line50athat is in fluid communication with aspirate inlets40′ of the Venturi pumps associated with upper mixing assemblies32a(e.g., Venturi pump36a) and a gas line50bthat is in fluid communication with aspirate inlets40′ of the Venturi pumps associated with lower mixing assemblies32b(e.g., Venturi pump36b).

Specifically, as seen inFIG. 2, a distal end52of a gas line50covers an aspirate inlet40′ of Venturi pump36. When a liquid enters Venturi pump36through motive fluid inlet38with sufficient velocity, the contents of gas line50are drawn into Venturi pump36through aspirate inlet40′.

In device10, a proximal end56aand56bof both gas lines50aand50brespectively emerges into the open air, thereby providing fluid communication between the aspirate inlets40′ of all eight Venturi pumps (including36aand36b) and the open air, so that when a respective liquid-driving pump44aor44bis activated to drive motive fluid into a motive fluid inlet38of respective Venturi pumps (e.g.,36aor36b), atmospheric air is draw into a respective gas line50aor50bthrough distal ends52thereof to enter the Venturi pump36through the respective aspirate inlets40′ to be mixed with the motive fluid.

Device10further comprises electrically-controlled gas-inlet needle valves58aand58b, each functionally associated with one of the two gas lines50aand50b, respectively. Each gas-inlet valve58aand58bhas:a closed state preventing flow of atmospheric air through a respective gas line50aor50bto aspirate inlets40′ of Venturi pumps of a respective mixing assembly32aor32b; anda plurality of open states, each such open state allowing flow of atmospheric air through a respective gas line50aor50bto aspirate inlets40′ of Venturi pump36of a respective mixing assembly32aor32b, where each open state is differentiated from the other open states by the degree that the valve58aor58bis open and therefore the rate that the air passes through a gas line50to the Venturi pumps.

Device10further comprises two gas reagent reservoirs60and two liquid reagent reservoirs62, one reagent reservoir60and one liquid reagent reservoir62associated with each mixing assembly32aor32b, each such reservoir in fluid communication with an aspirate inlet40″ of a Venturi pump36aor36bthrough one of two reagent supply lines64. Device10further comprises two electrically-controlled reagent valves66aand66bfunctionally associated with each one of the reagent supply lines64of one of the mixing assemblies32aor32brespectively, each reagent valve66aand66bhaving three states:a closed state preventing flow of reagent through an associated reagent supply line64to an aspirate inlet40″ of a respective Venturi pump36aor36bof a respective mixing assembly32aor32b;a first open state, allowing flow of gas reagent from an associated gas reagent reservoir60through an associated reagent supply line64to an aspirate inlet40″ of a respective Venturi pump36aor36bof a respective mixing assembly32aor32b; anda second open state, allowing flow of liquid reagent from an associated liquid reagent reservoir62through an associated reagent supply line64to an aspirate inlet40″ of a respective Venturi pump36aor36bof a respective mixing assembly32aor32b.

Covering a portion of each one of conduits48through which liquid flows from a liquid-driving pump44aor44bto Venturi pumps36aor36bis one of two electrical heating pads68configured, when activated, to heat liquid located inside conduit48that subsequently exits Venturi pump outlets42. The two heating pads68are independently activatable. In such a way, each one of heating pads68is configured to heat the liquid contents of chamber14located in proximity of a respective mixing assembly32a(liquid in upper portion16a) or32b(liquid in lower portion16b) without substantial heating of contents of chamber14located in proximity of the other mixing assembly.

For use, digestion chamber14of vessel12of device10is filled with wastewater for processing, for example, black water or agricultural manure slurry through inlet22and then a wastewater processing mode is selected.

Full Aerobic Mode

In a first, all aerobic, mode, both liquid-driving pumps44aand44bare activated to operate the respective mixing assemblies32aand32bsimultaneously and both gas inlet valves58are put in an open state. Substantially all the contents of chamber14are aerated and mixed by the action of the eight Venturi pumps (e.g.,36aand36b), allowing for aerobic digestion thereof. Aerobic digestion is optionally aided by activating one or both heating pads68or by adding gas or liquid reagents by selectively opening reagent valves66aand66bas desired.

As known in the art, sufficient aerobic digestion yields water of sufficient purity to be removed from vessel12through outlet24for subsequent use or for disposal.

Full Anaerobic or Anoxic Mode

In a second, all anaerobic (or anoxic), mode, both liquid-driving pumps44aand44bare activated to operate the respective mixing assemblies32aand32bsimultaneously and both gas inlet valves58are put in closed state. Substantially all the contents of chamber14are mixed by the action of the eight Venturi pumps (e.g.,36aand36b) but since gas inlet valves58aand58bare closed, no air enters chamber14. As the concentration of oxygen in the contents of chamber14is reduced due to the microbial digestion, the nature of the microbial population therein changes so that the proportion of aerobic microorganisms is reduced while the proportion of facultative and anaerobic microorganisms increases. As a result, the wastewater that is initially subject to aerobic digestion is eventually subject to anaerobic and even anoxic digestion. The anaerobic or anoxic digestion is optionally aided by activating one or both heating pads68or by adding gas or liquid reagents by selectively opening reagent valves66as desired. For example, to encourage methane-forming anaerobic bacteria instead of acid-forming anaerobic bacteria, it is preferred to control pH to be between 6.5 and 8 by addition of pH-modifying reagents and to control the temperature, where the exact temperature range depends on the desired species of methanogenic bacteria in the wastewater.

The full anaerobic or anoxic digestion mode is typically useful for reducing the amount of sludge that accumulates in sludge accumulation portion26and for producing biogas from wastewater.

It is important to note that anaerobic and anoxic digestion typically produces foul smelling and toxic gases. Accordingly, the full anaerobic or anoxic digestion mode is optionally preceded by aerobic digestion (to produce sludge) and is typically followed by an aerobic digestion mode finishing step as described above to eliminate toxic and foul-smelling gases prior to use or for disposal of the processed wastewater. In some embodiments, the modes are serially alternated a number of times: aerobic, anaerobic, aerobic, anaerobic and so on, as required.

Mixed Mode

In a third, mixed, mode, aerobic and anaerobic (or anoxic) digestions are performed simultaneously in digestion chamber14. Specifically, both liquid-driving pumps44aand44bare activated, while gas inlet valve58bof the lower mixing assembly32bis in the closed state and gas inlet valve58aof the upper mixing assembly32ais in an open state. As a consequence, the contents of upper portion16aof chamber14are aerated and mixed by the action of associated Venturi pumps (such as36a) allowing for aerobic digestion thereof. In contrast, the contents of lower portion16bof chamber14are mixed by the action of associated Venturi pumps (such as36b) but since gas inlet valve58bis closed, the contents of lower portion16bof chamber14become increasingly anaerobic or anoxic, as described above. The aerobic digestion in upper portion16aand/or the anaerobic/anoxic digestion in lower portion16bis optionally aided by activating a respective heating pad68or by adding gas or liquid reagents by selectively opening a respective reagent valve66as desired. The relative volume of wastewater undergoing aerobic digestion compared to the volume of wastewater undergoing anaerobic digestion can be varied by changing the relative pumping rate of the respective liquid-driving pumps44aand44b.

The mixed mode is particularly useful for continuous processing of wastewater. Wastewater is primarily processed by aerobic digestion in upper portion16a. Produced sludge settles to lower portion16bto undergo anaerobic digestion so there is little sludge formation and efficient biogas formation. Foul smelling gases that are emitted by the anaerobic digestion rise to upper portion16ato be immediately neutralized.

In an alternative embodiment, the entire chamber14is operated for aerobic digestion as described above to process wastewater by aerobic digestion at a maximal capacity. When a substantial amount of sludge accumulates in lower portion16b, chamber14is operated so that wastewater and sludge in lower portion16bundergoes anaerobic digestion to reduce the amount of sludge while the wastewater in upper portion16aundergoes aerobic digestion allowing further processing of wastewater by aerobic digestion (at a reduced capacity) and to neutralize the foul smelling gases released by the anaerobic digestion.

An additional embodiment of a device according to the teachings herein, device70, is schematically depicted in side cross section inFIG. 3. Device70has many of the same components as discussed above with reference to device10, with two notable differences. A first notable difference is that chamber outlet24provides fluid communication from lower portion16bof chamber14. A second notable difference is the presence of a third mixing assembly32clocated between upper mixing assembly32aand lower mixing assembly32b, defining a middle portion16cof digestion chamber14.

Device70can be operated substantially as device10, with the exception that processed wastewater is removed from lower portion16bof chamber14through chamber outlet24. During operation, aerobic or anaerobic digestion is independently maintained or changed in portions16a,16band16c.

A particular mode of operation that can be implemented using device70comprises simultaneous aerobic digestion in upper portion16a, aerobic digestion in lower portion16band anaerobic (or anoxic) digestion in middle portion16c. Toxic and foul smelling gases produced by anaerobic digestion in middle portion16care neutralized in upper portion16a, while wastewater that enters chamber14through inlet22undergoes aerobic digestion in upper portion16a, anaerobic digestion in middle portion16cto digest sludge and undergoes aerobic digestion as a finishing step in lower portion16bprior to use or disposal.

In some embodiments, during processing of wastewater, aerobic digestion is continuously maintained in upper portion16a, anaerobic digestion is continuously maintained in lower portion16b, and middle portion16bis alternated between aerobic and anaerobic digestion.

The Venturi pump outlets of a device according to the teachings herein are directed in any suitable direction. In some preferred embodiments, the Venturi pump outlets are directed in a way relative to the inlet of a respective liquid-driving pump to encourage generation of a cyclical motion of liquid inside a corresponding portion of the chamber. In device10depicted inFIG. 1, Venturi pump outlets42are directed downwardly parallel to vertical axis20of chamber14. In some embodiments, the Venturi pump outlets are directed upwardly parallel to the vertical axis of the chamber. In some embodiments, the Venturi pump outlets are directed perpendicular to the vertical axis of the chamber.

In device10depicted inFIG. 1and in device70depicted inFIG. 3, each mixing assembly is provided with a dedicated liquid-driving pump to drive liquid through respective Venturi pumps so that the mixing assemblies are independently operable by independently activating and controlling the dedicated pump or pumps. In some embodiments, liquid is driven through the Venturi pumps of both mixing assemblies by shared liquid-driving pump or pumps. In such embodiments, the device is typically provided with differentially controllable valves allowing the relative amount of liquid driven through the different Venturi pumps of the different mixing assemblies to be controlled (including to be entirely prevented), thereby and allowing the mixing assemblies to be independently operable by independently opening and closing the valves associated with each mixing assembly.

Citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the invention.

Section headings are used herein to ease understanding of the specification and should not be construed as necessarily limiting.