Nanobubbles for anaerobic processes

Abstract

Methods and systems for treating a stream containing materials (e.g., biomass such as plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) with nanobubbles are provided herein. One such method comprises the steps of generating nanobubbles in wastewater sludge of a wastewater treatment system to produce nanobubble-containing sludge, wherein the wastewater sludge has a higher solid content than the input stream to the wastewater treatment system; and processing the nanobubble-containing sludge in an anaerobic reactor of the wastewater treatment system. TIFF2026518260000002.tif202170

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Patent Application No. 63 / 469,302, filed on 26 May 2023, which is incorporated herein by reference in its entirety.

[0002] Technical field This disclosure relates to a system and method for enhancing anaerobic processes with nanobubbles. [Background technology]

[0003] background Biomass contains pollutants and pathogens, which pose a threat to the environment, climate, and human health. Biomass also contains organic matter and nutrients, which make it possible to use treated biomass, free from pollutants and pathogens, for a variety of purposes, such as fertilizer, electricity, heat, and fuel. [Overview of the Initiative]

[0004] overview The inventors have discovered that anaerobic processes of materials such as biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or combinations thereof) can be enhanced by generating nanobubbles in a stream containing the material. The methods described herein involve a step of generating nanobubbles in a variety of systems, including, but not limited to, wastewater treatment systems, energy production systems, fertilizer production systems, and anaerobic fermentation systems. In some embodiments, the methods described herein involve a step of generating nanobubbles in various types of sludge produced during wastewater treatment, including, but not limited to, primary sludge, activated sludge, waste activated sludge, returned activated sludge, or combinations thereof.

[0005] Accordingly, aspects of the present disclosure provide a method comprising the steps of: generating nanobubbles in a stream of a system to produce a nanobubble-containing stream; and processing the nanobubble-containing stream in an anaerobic reactor of the system, wherein the stream has a solids concentration of at least 1,200 mg / L.

[0006] In some embodiments, the dissolved oxygen content of the stream is substantially the same as that of the nanobubble-containing stream.

[0007] In some embodiments, the stream has a solids concentration ranging from 1,200 mg / L to 90,000 mg / L.

[0008] In some embodiments, the stream has a dry solids content of at least 0.12% by weight. In some embodiments, the stream has a dry solids content of at least 0.12% by weight to at least 4.5% by weight.

[0009] In some embodiments, the gas is selected from air, argon, hydrogen, biogas, methane, carbon dioxide, nitrogen, oxygen, or ozone.

[0010] In some embodiments, the stream includes biomass. In some embodiments, the biomass includes plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof.

[0011] In some embodiments, the system comprises at least one nanobubble generator.

[0012] In some embodiments, the system is a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system. In some embodiments, the system is a wastewater treatment system, and the stream contains wastewater sludge.

[0013] Aspects of the present disclosure provide a method comprising the steps of: generating nanobubbles in a stream of a system to produce a nanobubble-containing stream; and processing the nanobubble-containing stream in an anaerobic reactor of the system, wherein the stream has a chemical oxygen demand of at least 2000 mg / L and / or the stream has a biological oxygen demand of at least 1000 mg / L.

[0014] In some embodiments, the stream has a chemical oxygen demand of 2,000 mg / L to 5,000,000 mg / L.

[0015] In some embodiments, the stream has a biological oxygen demand of 1,000 mg / L to 2,500,000 mg / L.

[0016] Accordingly, aspects of this disclosure provide a method comprising the steps of: generating nanobubbles in wastewater sludge of a wastewater treatment system in order to produce nanobubble-containing sludge, wherein the wastewater sludge has a higher solid content than the input stream to the wastewater treatment system; and processing the nanobubble-containing sludge in an anaerobic reactor of the wastewater treatment system.

[0017] In some embodiments, the method comprises the step of separating an input stream into a liquid stream and primary sludge, where the wastewater sludge is based on primary sludge.

[0018] In some embodiments, the step of generating nanobubbles in wastewater sludge comprises the step of generating nanobubbles in primary sludge.

[0019] In some embodiments, the method comprises a step of concentrating primary sludge, and the step of generating nanobubbles in wastewater sludge comprises a step of generating nanobubbles in the concentrated primary sludge.

[0020] In some embodiments, the method comprises the steps of generating nanobubbles in the primary sludge to generate primary sludge containing nanobubbles; and concentrating the primary sludge containing nanobubbles.

[0021] In some embodiments, the step of separating the input stream comprises processing the input stream using one or more of a clarifier, chemically enhanced primary treatment, high rate clarification, primary effluent filtration, primary filtration, rotary belt filtration, microscreen, or dissolved air flotation clarifier.

[0022] In some embodiments, the method comprises the step of separating an input stream in a solid-liquid separator of a wastewater treatment system.

[0023] In some embodiments, the method comprises providing a liquid stream output from an anaerobic reactor to a solid-liquid separator.

[0024] In some embodiments, the method comprises processing an input stream to generate waste activated sludge, wherein the wastewater sludge is based on the waste activated sludge.

[0025] In some embodiments, the step of generating nanobubbles in the wastewater sludge comprises generating nanobubbles in the waste activated sludge.

[0026] In some embodiments, the method comprises the step of concentrating the waste activated sludge, and the step of generating nanobubbles in the wastewater sludge comprises generating nanobubbles in the concentrated waste activated sludge.

[0027] In some embodiments, the step of processing an input stream to generate waste activated sludge comprises processing a liquid stream separated from the input stream.

[0028] In some embodiments, the method comprises the step of generating waste activated sludge in a biological reactor of a wastewater treatment system.

[0029] In some embodiments, the process of processing an input stream in a biological reactor comprises the process of processing an input stream under aerobic conditions.

[0030] In some embodiments, the method comprises the step of outputting waste activated sludge and a second liquid stream from a biological reactor.

[0031] In some embodiments, the method comprises the steps of: separating a second liquid stream into a return sludge and a third liquid stream; and providing the return sludge to a biological reactor.

[0032] In some embodiments, the step of separating the second liquid stream comprises separating the second liquid stream using one or more of a secondary clarifier or membrane filtration.

[0033] In some embodiments, the step of generating nanobubbles in wastewater sludge comprises the step of generating nanobubbles in wastewater sludge output from an anaerobic reactor.

[0034] In some embodiments, the method comprises heating or cooling wastewater sludge output from an anaerobic reactor before and / or after the step of generating nanobubbles in wastewater sludge.

[0035] In some embodiments, the method comprises the step of heating or cooling wastewater sludge output from an anaerobic reactor by passing the wastewater sludge from the anaerobic reactor through a heat exchanger.

[0036] In some embodiments, the wastewater sludge includes waste activated sludge having a solids concentration of at least 1,200 mg / L.

[0037] In some embodiments, the wastewater sludge includes waste activated sludge having a solids concentration of at least 4,800 mg / L.

[0038] In some embodiments, the wastewater sludge includes waste activated sludge having a solids concentration of at least 45,000 mg / L.

[0039] In some embodiments, the wastewater sludge includes primary sludge having a solids concentration of at least 15,000 mg / L.

[0040] In some embodiments, the wastewater sludge includes primary sludge having a solids concentration of at least 45,000 mg / L.

[0041] In some embodiments, the wastewater sludge comprises waste activated sludge having a dry solids content of at least 0.12% by weight.

[0042] In some embodiments, the wastewater sludge includes waste activated sludge having a dry solids content of at least 0.48% by weight.

[0043] In some embodiments, the wastewater sludge comprises waste activated sludge having a dry solids content of at least 4.5% by weight.

[0044] In some embodiments, the wastewater sludge includes primary sludge having a dry solids content of at least 1.5% by weight.

[0045] In some embodiments, the wastewater sludge includes primary sludge having a dry solids content of at least 4.5% by weight.

[0046] In some embodiments, the process of generating nanobubbles comprises the process of generating nanobubbles of air, hydrogen, biogas, methane, carbon dioxide, nitrogen, oxygen, or ozone.

[0047] In some embodiments, the method includes a dissolved oxygen content of wastewater sludge which is substantially the same as that of nanobubble-containing sludge.

[0048] In some embodiments, the method comprises the steps of: providing a first portion of an input stream to an anaerobic reactor; and separating a second portion of the input stream into a liquid stream and a solid stream, wherein the step of generating nanobubbles in wastewater sludge comprises the step of generating nanobubbles in a stream based on the solid stream.

[0049] In some embodiments, the method comprises the steps of: generating nanobubbles in a first portion of an input stream to produce a nanobubble-containing input stream; and providing the nanobubble-containing input stream to an anaerobic reactor.

[0050] In some embodiments, the method comprises a step of concentrating sludge separated from an input stream in order to produce wastewater sludge.

[0051] In some embodiments, the sludge includes activated sludge received from a biological reactor in a wastewater treatment system.

[0052] In some embodiments, the sludge includes primary sludge separated from the input stream.

[0053] In some embodiments, the sludge concentration step comprises the steps of: generating wastewater sludge and a third liquid stream; and providing the third liquid stream to a separator that separates primary sludge from the input stream.

[0054] In some embodiments, the sludge concentration step comprises a step of processing the sludge using one or more of the following: dissolved air flotation, centrifuge, gravity belt concentrator, gravity, or rotary drum concentrator.

[0055] The aspect of this disclosure provides a method comprising the steps of: generating nanobubbles in wastewater sludge of a wastewater treatment system to produce nanobubble-containing sludge, wherein the dissolved oxygen content of the wastewater sludge is substantially the same as that of the nanobubble-containing sludge; and processing the nanobubble-containing sludge in an anaerobic reactor of the wastewater treatment system.

[0056] In some embodiments, the step of generating nanobubbles comprises the step of generating nanobubbles of an oxygen-containing gas.

[0057] In some embodiments, the oxygen-containing gas is air.

[0058] In some embodiments, a method comprising the step of generating nanobubbles comprises the step of generating nanobubbles of air, hydrogen, biogas, methane, carbon dioxide, nitrogen, oxygen, or ozone.

[0059] The aspect of this disclosure provides a method comprising the steps of: generating nanobubbles in wastewater sludge of a wastewater treatment system to produce nanobubble-containing sludge, wherein the wastewater sludge has a solid content of at least 1,200 mg / L; and processing the nanobubble-containing sludge in an anaerobic reactor of the wastewater treatment system.

[0060] In some embodiments, the solids concentration is at least 1,200 mg / L to at least 90,000 mg / L.

[0061] In some embodiments, the step of generating nanobubbles comprises the step of generating nanobubbles of an oxygen-containing gas.

[0062] In some embodiments, the oxygen-containing gas is air.

[0063] In some embodiments, the process of generating nanobubbles comprises the process of generating nanobubbles of air, hydrogen, biogas, methane, carbon dioxide, nitrogen, oxygen, or ozone.

[0064] Aspects of this disclosure provide a system comprising: a nanobubble generator configured to generate nanobubbles in biomass having a higher solid content than the input stream to the system in order to produce nanobubble-containing biomass; and an anaerobic reactor configured to process the nanobubble-containing biomass.

[0065] In some embodiments, the Disclosure provides a wastewater treatment system comprising: a nanobubble generator configured to generate nanobubbles in wastewater sludge of a wastewater treatment system having a higher solid content than the input stream to the wastewater treatment system in order to produce nanobubble-containing sludge; and an anaerobic reactor configured to process the nanobubble-containing sludge.

[0066] In some embodiments, the system comprises a first solid-liquid separation module configured to separate an input stream into a primary sludge and a first liquid stream, where the wastewater sludge is based on the primary sludge.

[0067] In some embodiments, the nanobubble generator is positioned along a channel between the first solid-liquid separation module and the anaerobic reactor.

[0068] In some embodiments, the first solid-liquid separation module comprises a first solid-liquid separator.

[0069] In some embodiments, the system comprises a first concentrator configured to concentrate primary sludge in order to generate wastewater sludge.

[0070] In some embodiments, the nanobubble generator is positioned along a channel between the first concentrator and the anaerobic reactor.

[0071] In some embodiments, the nanobubble generator is positioned along the upstream channel of the first concentrator.

[0072] In some embodiments, the system comprises a return channel connecting an anaerobic reactor to a first solid-liquid separation module.

[0073] In some embodiments, the system comprises a sludge activation module configured to process a first liquid stream separated from an input stream and to output activated sludge and a second liquid stream, where the wastewater sludge is based on activated sludge.

[0074] In some embodiments, the nanobubble generator is positioned along a channel between the sludge activation module and the anaerobic reactor.

[0075] In some embodiments, the sludge activation module comprises a biological reactor.

[0076] In some embodiments, the system comprises a second concentrator configured to concentrate activated sludge in order to generate wastewater sludge.

[0077] In some embodiments, the nanobubble generator is positioned along a channel between the second concentrator and the anaerobic reactor.

[0078] In some embodiments, the nanobubble generator is positioned along the flow path between the sludge activation module and the second concentrator.

[0079] In some embodiments, the system comprises a second solid-liquid separation module configured to separate a second liquid stream into a return activated sludge and a third liquid stream; and a return sludge channel connecting the second solid-liquid separation module to a biological reactor.

[0080] In some embodiments, the nanobubble generator is positioned along a recirculation channel connected to an anaerobic reactor.

[0081] In some embodiments, the system comprises heat exchangers arranged along a recirculation channel.

[0082] In some embodiments, the system comprises an input nanobubble generator positioned along an input channel into an anaerobic reactor, and a second nanobubble generator configured to generate nanobubbles in the input stream.

[0083] Aspects of this disclosure provide a method comprising the steps of: generating nanobubbles in an input stream of a wastewater treatment system in order to generate a nanobubble-containing input stream; and processing the nanobubble-containing input stream in an anaerobic reactor of the wastewater treatment system.

[0084] The methods and systems described herein relating to the generation of nanobubbles in materials such as biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or combinations thereof) offer several improvements over conventional methods. Such improvements include, but are not limited to, the following:

[0085] (a) Reduction in the cost and disposal of chemical metal ion chelating agents; this reduction is at least partly due to a reduction in hydrogen sulfide production, resulting in a reduction in the concentration of biogas produced in systems containing nanobubbles, such as biomass (e.g., wastewater treatment systems, energy production systems, fertilizer production systems, or anaerobic fermentation systems), compared to systems containing conventional materials lacking nanobubbles (e.g., biomass).

[0086] (b) Reduction of disposal and transport costs of residual biosolids; this reduction is at least in part due to improved fermentation and further reduction of volatile organic compounds in nanobubble-containing materials (e.g., nanobubble-containing biomass) compared to systems containing conventional materials (e.g., biomass) that lack nanobubbles.

[0087] (c) Reduction of capital costs; this reduction is at least in part due to the increased organic load in systems containing nanobubble-containing materials (e.g., nanobubble-containing biomass) (e.g., wastewater treatment systems, energy production systems, fertilizer production systems, or anaerobic fermentation systems) compared to systems containing conventional materials lacking nanobubbles (e.g., biomass).

[0088] (d) Increased biogas availability for facility energy offsetting; this increase is at least in part due to improved process stabilization and alkalinity recovery in nanobubble-containing materials (e.g., nanobubble-containing biomass) compared to conventional materials (e.g., biomass) that lack nanobubbles.

[0089] (e) Reduced facility downtime and reduced operation and maintenance costs; this reduction is at least in part due to reduced foam and scum formation in nanobubble-containing materials (e.g., nanobubble-containing biomass) compared to conventional materials lacking nanobubbles (e.g., biomass).

[0090] (f) Increased processing efficiency, at least in part, due to the direct injection of nanobubbles into the material (e.g., biomass); direct injection of nanobubbles avoids the dilution of the material into an anaerobic digester that occurs when nanobubble-containing water is pre-injected into the material.

[0091] (g) Continuous operation of the anaerobic digester and accessibility of the nanobubble generator for repair; this is at least in part due to the system including one or more nanobubble generators independent of (e.g., located outside of) the anaerobic digester.

[0092] Other features and advantages of the present invention will become apparent from the following detailed description and claims. [Brief explanation of the drawing]

[0093] [Figure 1A] This is a schematic diagram illustrating an exemplary system for treating wastewater sludge with nanobubbles. [Figure 1B] See the explanation in Figure 1A. [Figure 1C] See the explanation in Figure 1A. [Figure 2A] This is a flowchart illustrating an exemplary method for treating wastewater sludge with nanobubbles. [Figure 2B] See the explanation in Figure 2A. [Figure 2C] See the explanation in Figure 2A. [Figure 2D] See the explanation in Figure 2A. [Modes for carrying out the invention]

[0094] Detailed explanation The following is a more detailed description of various concepts relating to the methods and systems of the present invention concerning the treatment of biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) with nanobubbles, as well as exemplary embodiments of such methods and systems. In some embodiments, the methods and systems described herein relate to the anaerobic digestion of nanobubble-containing biomass.

[0095] Any method and system described herein may include a step of generating nanobubbles in biomass. The following description relates to the treatment of wastewater sludge and is not intended to limit the scope of the methods and systems described herein. The methods and systems described herein are applicable to the treatment of any biomass sludge, including, but not limited to, plant biomass, animal biomass, agricultural biomass, wastewater sludge, or combinations thereof.

[0096] Referring to Figure 1A, an exemplary method for treating wastewater sludge with nanobubbles in an exemplary wastewater treatment system 100 is described.

[0097] The first portion 110a of the input stream 110 flows into the anaerobic reactor 150, where anaerobic digestion takes place. Anaerobic digestion and the anaerobic reactor are described in more detail in the section titled "Anaerobic Digestion and Anaerobic Reactor".

[0098] Nanobubbles may be generated in the sludge output by passing the sludge output from the anaerobic reactor 150 through a nanobubble generator 160d positioned along a recirculation channel connected to the anaerobic reactor 150. Nanobubbles and nanobubble generators are described in more detail in the section titled "Nanobubbles and Nanobubble Generators".

[0099] The second portion 110b of the input stream 110 flows into the solid-liquid separation module 120, where it is separated into sludge and a liquid stream. The separation of solids and liquids is described in more detail in the section titled "Solid-Liquid Separation Module".

[0100] Figure 1A illustrates the flow of the input stream 110 into the solid-liquid separation module 120 and the anaerobic reactor 150, but the methods and systems described herein also include flowing the entire input stream into the solid-liquid separation module 120 or into the anaerobic reactor 150. Thus, the methods and systems described herein include the step of flowing all or part of the input stream into the solid-liquid separation module or into the anaerobic reactor.

[0101] The liquid stream flows into the sludge activation module 130 to generate activated sludge. The sludge activation module 130 may include, for example, a solid-liquid separation element, a biological reactor, or other suitable components. Sludge activation is described in more detail in the section titled "Sludge Activation Module".

[0102] The sludge output from the solid-liquid separation module 120 and the sludge output from the sludge activation module 130 are passed through nanobubble generators 160a and 160b, respectively, to generate nanobubble-containing sludge.

[0103] Next, the nanobubble-containing sludge may be concentrated in the concentrator 140. Sludge concentration will be described in more detail in the section titled "Sludge Concentration".

[0104] The concentrated sludge may be passed through a nanobubble generator 160c to produce concentrated nanobubble-containing sludge, which may then be digested anaerobically in an anaerobic reactor 150. In some embodiments, nanobubbles are generated in the sludge only before sludge concentration. In some embodiments, nanobubbles are generated in the sludge only after sludge concentration. In some embodiments, as illustrated in Figure 1A, nanobubbles are generated in the sludge both before and after sludge concentration. Alternatively or additionally, nanobubbles may be generated in the sludge during sludge concentration. In such cases, nanobubbles may be generated in the sludge during sludge concentration in a sludge holding tank, a homogenization tank, or other suitable sludge thickener.

[0105] Referring to Figure 1B, an exemplary method for treating wastewater sludge with nanobubbles in an exemplary wastewater treatment system 102 is illustrated.

[0106] The input stream 110 flows into the solid-liquid separator 122a. The input stream 110 may include wastewater input to the wastewater system 102. Alternatively or additionally, output streams from one or more components of the wastewater system 102 may flow into the solid-liquid separator 122a. For example, as shown in Figure 1B, the liquid stream output 117 from the anaerobic reactor 150 is merged with the input stream 110 and flows into the solid-liquid separator 122a. In some embodiments, a portion of the input stream 110 flows directly into the anaerobic reactor 150.

[0107] The input stream 110 is separated into a liquid stream 112a and primary sludge 111 within a solid-liquid separator 122a. The input stream may be separated using one or more of the following: a clarifier, chemically enhanced primary treatment, high-speed clarification, primary effluent filtration, primary filtration, rotary belt filtration, microscreen, dissolved air flotation clarifier, gravity filtration, or other suitable solid-liquid separation techniques. The primary sludge 111 has a higher solid content than the input stream 110.

[0108] The liquid stream 112a flows into the biological reactor 132, where it is processed to become the liquid stream 112b and the waste activated sludge 115a. The liquid stream 112a may be processed in the biological reactor 132, for example, under aerobic and / or anaerobic conditions. The waste activated sludge 115a has a higher solids content than the liquid stream 112a, the input stream 110, or both. In some embodiments, the system 102 does not include a solid-liquid separator 122a, and the input stream 110 flows directly into the biological reactor 132.

[0109] Nanobubbles may be generated in the primary sludge 111 and / or waste activated sludge 115a, which results in nanobubble-containing sludge. Alternatively or additionally, as illustrated in Figure 1B, the primary sludge 111 and / or waste activated sludge 115a may be concentrated, and nanobubbles may be generated in the concentrated primary sludge and / or concentrated activated sludge; this also results in nanobubble-containing sludge. The primary sludge 111 and / or waste activated sludge 115a may be concentrated by processing the sludge using one or more of the following preferred concentration techniques: dissolved air flotation, centrifuge, gravity belt concentrator, gravity, rotary drum concentrator, or other suitable concentration techniques.

[0110] As shown in Figure 1B, the primary sludge 111 generated in the solid-liquid separator 122a is concentrated in the concentrator 142a, and nanobubbles are generated in the concentrated primary sludge using the nanobubble generator 160a to produce nanobubble-containing primary sludge 111a.

[0111] Nanobubbles may be generated in the waste activated sludge before, after, or both of the above. For example, as shown in Figure 1B, nanobubbles are generated in the waste activated sludge 115a produced in the biological reactor 132 using a nanobubble generator 160d to produce nanobubble-containing waste activated sludge 115c. The nanobubble-containing sludge 115c is concentrated in a concentrator 142b, and then nanobubbles are generated in the concentrated waste activated sludge using a nanobubble generator 160b to produce nanobubble-containing waste activated sludge 115d. In some embodiments, only a single nanobubble generator is used to generate nanobubbles in the waste activated sludge 115a, for example, only the nanobubble generator 160d upstream of the concentrator 142b or only the nanobubble generator 160b downstream of the concentrator 142b.

[0112] Nanobubble generators 160a, 160b, 160c (described later), and 160d are flow-through type nanobubble generators arranged, for example, along the sludge flow path, and directly generate nanobubbles in the sludge. Other types of nanobubble generators, such as underwater nanobubble generators, may also be used.

[0113] The liquid stream 112b output from the biological reactor 132 is processed in the solid-liquid separator 122b using one or more of the following: a secondary clarifier or membrane filtration, to become the liquid stream 112c, waste activated sludge 115b, and return sludge 114. In the illustrated example, the waste activated sludge 115b output from the solid-liquid separator 122b merges with the waste activated sludge 115a produced in the biological reactor 132. The combined waste activated sludge, collectively referred to as waste activated sludge 115, is processed through the nanobubble generator 160d, the concentrator 142b, and the nanobubble generator 160b to produce nanobubble-containing waste activated sludge 115d. The return sludge 114 is returned to the biological reactor 132 for processing to become return activated sludge. In some embodiments, only the waste activated sludge 115a from the biological reactor 132 is processed through a nanobubble generator and a concentrator, and the entire sludge output from the solid-liquid separator 122b is returned to the biological reactor 132. In some embodiments, separate nanobubble generators, concentrators, or both may be used to process the waste activated sludge 115a and waste activated sludge 115b, respectively.

[0114] In the illustrated example, the liquid stream 112c flows into the disinfection unit 124, where the pathogens in the liquid stream 112c are neutralized. The output from the disinfection unit 124 exits the wastewater system 102 as the output stream 113. In some embodiments, the liquid stream 112c is discharged from the wastewater treatment system described herein without undergoing disinfection treatment. For example, the liquid stream may exit the wastewater treatment system and flow into the environment.

[0115] Primary sludge 111 and / or waste activated sludge 115 (e.g., nanobubble-containing primary sludge 111a and nanobubble-containing waste activated sludge 115d), one or both of which contain nanobubbles, are processed anaerobically, e.g., digested, in an anaerobic reactor 150. Nanobubbles are generated in the wastewater sludge 151 output from the anaerobic reactor 150 using a nanobubble generator 160c, thereby producing nanobubble-containing recirculated sludge 151a. The nanobubble generator 160c is a flow-through type nanobubble generator positioned along the recirculation channel of sludge returning from the anaerobic reactor 150.

[0116] The wastewater sludge output from the anaerobic reactor may be heated or cooled before and / or after generating nanobubbles in the wastewater sludge. For example, as shown in Figure 1B, the wastewater sludge 151 output from the anaerobic reactor 150 is heated or cooled before generating nanobubbles in the wastewater sludge. In such a case, the wastewater sludge 151 output from the anaerobic reactor 150 may be heated or cooled by passing the wastewater sludge 151 from the anaerobic reactor 150 through a heat exchanger 152.

[0117] The output from the anaerobic reactor 150 may be further processed in the wastewater treatment system 102. As shown in Figure 1B, the liquid stream output 117 from the anaerobic reactor 150 is flowed into the solid-liquid separator 122a for processing into primary sludge 111 and liquid stream 112a. Alternatively or additionally, the output from the anaerobic reactor 150 may be output from the wastewater treatment system 102. As shown in Figure 1B, the solid stream output 116 from the anaerobic reactor 150 is flowed out of the wastewater treatment system 102.

[0118] Any method and system described herein may include a step of generating nanobubbles in an input stream. Referring to Figure 1C, an exemplary method for treating an input stream and wastewater sludge with nanobubbles in an exemplary wastewater treatment system 104 is illustrated.

[0119] To generate a nanobubble-containing input stream 109a, the first portion 110a of the input stream 110 is flowed into the nanobubble generator 160d. An anaerobic process of the nanobubble-containing input stream 109a, such as digestion, is carried out in the anaerobic reactor 150. The output from the anaerobic reactor 150 may be processed in the wastewater treatment system 104. As shown in Figure 1C, the liquid stream output 117 from the anaerobic reactor 150 is merged with the input stream 110 for further processing in the wastewater treatment system 104. Alternatively or additionally, the output from the anaerobic reactor 150 may be output from the wastewater treatment system 104. As shown in Figure 1C, the solid stream output 116 from the anaerobic reactor 150 is flowed out of the wastewater treatment system 102.

[0120] The second portion 110b of the input stream 110 flows into the solid-liquid separation module 120, where it is separated into primary sludge 111 and liquid stream 112a. The liquid stream 112a is processed in the sludge activation module 130 to produce waste activated sludge 115. The primary sludge 111 and waste activated sludge 115 are processed as described above with respect to Figure 1B; for example, nanobubbles are generated in the primary sludge 111a and / or waste activated sludge 115 to generate nanobubble-containing sludge 111a and / or nanobubble-containing waste activated sludge 115d, the nanobubble-containing sludge is concentrated in the concentrators 142a and 142b, respectively, and the nanobubble-containing sludge is processed in the anaerobic reactor 150.

[0121] Although not shown, the wastewater sludge output from the anaerobic reactor 150 may be processed to produce nanobubble-containing recirculated sludge, which may then be returned to the anaerobic reactor 150 as described above for Figure 1B. Other elements of system 102 in Figure 1B may also be incorporated into system 104 in Figure 1C.

[0122] The disclosure also provides a wastewater treatment method comprising the step of generating nanobubbles in wastewater sludge and / or in the input stream to a wastewater treatment system.

[0123] In one example, as shown in Figure 2A, the method described herein may include the steps of generating nanobubbles in wastewater sludge to produce nanobubble-containing sludge; and processing the nanobubble-containing sludge in an anaerobic reactor. Such a method may include the step of generating nanobubbles in primary sludge and / or activated sludge to produce nanobubble-containing primary sludge and / or nanobubble-containing activated sludge. Thus, in some embodiments, the method described herein further comprises the steps of separating the input stream into primary sludge and liquid stream; and / or processing the liquid stream to produce activated sludge. The primary sludge and activated sludge have a higher solids content than the input stream and liquid stream.

[0124] In one example, as shown in Figure 2B, the method described herein may include the steps of: generating nanobubbles in wastewater sludge to produce nanobubble-containing sludge, wherein the dissolved oxygen content of the wastewater sludge is substantially the same as that of the nanobubble-containing sludge; and processing the nanobubble-containing sludge in an anaerobic reactor. For example, the method described herein may include the steps of: generating nanobubbles of an oxygen-containing gas such as air in wastewater sludge to produce nanobubble-containing sludge, wherein the dissolved oxygen content of the wastewater sludge is substantially the same as that of the nanobubble-containing sludge; and processing the nanobubble-containing sludge in an anaerobic reactor.

[0125] For example, as shown in Figure 2C, the method described herein may include the steps of: generating nanobubbles in wastewater sludge to produce nanobubble-containing sludge, wherein the wastewater sludge has a solid content concentration of at least 1,200 mg / L to at least 90,000 mg / L; and processing the nanobubble-containing sludge in an anaerobic reactor.

[0126] In some ways, wastewater sludge has a concentration of 1,200 mg / L to 90,000 mg / L, 2,400 mg / L to 90,000 mg / L, 3,600 mg / L to 90,000 mg / L, 4,800 mg / L to 90,000 mg / L, 10,000 mg / L to 90,000 mg / L, 20,000 mg / L to 90,000 mg / L, 30,000 mg / L to 90,000 mg / L, 40,000 mg / L to 90,000 mg / L, 50,000 mg / L to 90,000 mg / L, 60,000 mg / L to 90,000 mg / L, 70,000 mg / L to 90,000 mg / L, and 80,000 mg / L to 90,000 mg / L. It has a solid concentration of mg / L, 1,200 mg / L to 80,000 mg / L, 1,200 mg / L to 70,000 mg / L, 1,200 mg / L to 60,000 mg / L, 1,200 mg / L to 50,000 mg / L, 1,200 mg / L to 40,000 mg / L, 1,200 mg / L to 30,000 mg / L, 1,200 mg / L to 20,000 mg / L, 1,200 mg / L to 10,000 mg / L, 1,200 mg / L to 4,800 mg / L, 1,200 mg / L to 3,600 mg / L, or 1,200 mg / L to 2,400 mg / L.

[0127] In one example, as shown in Figure 2D, the method described herein may include the steps of: generating nanobubbles in an input stream to produce a nanobubble-containing input stream; and processing the nanobubble-containing input stream in an anaerobic reactor.

[0128] The methods and systems described herein include a step of generating nanobubbles in any wastewater sludge. The terms “wastewater sludge” or “sludge” as used herein refer to any waste material or precipitate, whether solid, semi-solid, or liquid, produced by a wastewater treatment process. In some embodiments, the wastewater sludge has a higher solid content than the input stream to the wastewater treatment system. In some embodiments, the input stream to the wastewater treatment system includes municipal wastewater and / or industrial wastewater.

[0129] In some embodiments, the wastewater sludge includes waste activated sludge having a solids concentration of at least 1,200 mg / L, for example, at least 1,300 mg / L, at least 1,400 mg / L, at least 1,500 mg / L, at least 1,600 mg / L, at least 1,700 mg / L, at least 1,800 mg / L, at least 1,900 mg / L, or at least 2,000 or greater.

[0130] In some embodiments, prior to concentration, the wastewater sludge includes waste activated sludge having a solids concentration of at least 4,800 mg / L, for example, at least 4,900 mg / L, at least 5,000 mg / L, at least 5,100 mg / L, at least 5,200 mg / L, at least 5,300 mg / L, at least 5,400 mg / L, at least 5,500 mg / L, at least 5,600 mg / L, at least 5,700 mg / L, at least 5,800 mg / L, at least 5,900 mg / L, at least 6,000 mg / L or greater.

[0131] In some embodiments, after concentration, the wastewater sludge includes waste activated sludge having a solids concentration of at least 45,000 mg / L, for example, at least 46,000 mg / L, at least 47,000 mg / L, at least 48,000 mg / L, at least 49,000 mg / L, at least 50,000 mg / L, at least 55,000 mg / L, at least 60,000 mg / L, or greater.

[0132] In some embodiments, prior to concentration, the wastewater sludge includes primary sludge having a solids concentration of at least 15,000 mg / L, for example, at least 16,000 mg / L, at least 17,000 mg / L, at least 18,000 mg / L, at least 19,000 mg / L, at least 20,000 mg / L, at least 25,000 mg / L, at least 30,000 mg / L, or greater.

[0133] In some embodiments, after concentration, the wastewater sludge includes primary sludge having a solids concentration of at least 45,000 mg / L, for example, at least 46,000 mg / L, at least 47,000 mg / L, at least 48,000 mg / L, at least 49,000 mg / L, at least 50,000 mg / L, at least 55,000 mg / L, at least 60,000 mg / L, or greater.

[0134] In some embodiments, wastewater sludge has a solids concentration of at least 15,000 mg / L, for example, at least 16,000 mg / L, at least 17,000 mg / L, at least 18,000 mg / L, at least 19,000 mg / L, at least 20,000 mg / L, at least 25,000 mg / L, at least 30,000 mg / L, or greater. In some embodiments, wastewater sludge having a solids concentration of at least 15,000 mg / L is referred to as activated sludge.

[0135] In some embodiments, wastewater sludge has a solids concentration of at least 60,000 mg / L, for example, at least 60,000 mg / L, at least 65,000 mg / L, at least 70,000 mg / L, at least 75,000 mg / L, at least 80,000 mg / L, at least 90,000 mg / L, or greater. In some embodiments, wastewater sludge having a solids concentration of at least 60,000 mg / L is referred to as primary sludge.

[0136] In some aspects, the wastewater sludge has a dry solids content of at least 1.2% by weight, for example, at least 1.3% by weight, at least 1.4% by weight, at least 1.5% by weight, at least 2.0% by weight, at least 2.5% by weight, at least 3.0% by weight, at least 3.5% by weight, at least 4.0% by weight, at least 4.5% by weight, at least 5.0% by weight, at least 5.5% by weight, at least 6.0% by weight, at least 6.5% by weight, at least 7.0% by weight, at least 7.5% by weight, at least 8.0% by weight, at least 8.5% by weight, at least 9.0% by weight, at least 9.5% by weight, at least 10.0% by weight, or more.

[0137] The methods and systems described herein include the step of generating nanobubbles in any stream. In some embodiments, the stream includes biomass. As used herein, the term “biomass” refers to organic material derived from any living or recently living organism, such as plants or animals. Non-limiting examples of biomass include plant biomass (e.g., wood or wood processing waste, e.g., firewood, wood pellets, wood chips, timber, sawdust, and pulp); agricultural biomass (e.g., agricultural crops and waste materials derived therefrom, e.g., corn, soybeans, sugarcane, switchgrass, woody plants, algae, and processing residues of crops and food); animal biomass (e.g., animal manure; human wastewater; municipal solid waste such as paper products, food and cotton products); wastewater sludge (e.g., primary sludge, activated sludge, waste activated sludge, returned activated sludge, or a combination thereof); or any combination of these.

[0138] In some embodiments, the stream (e.g., biomass) has a solids concentration of at least 1,200 mg / L, for example, at least 1,300 mg / L, at least 1,400 mg / L, at least 1,500 mg / L, at least 1,600 mg / L, at least 1,700 mg / L, at least 1,800 mg / L, at least 1,900 mg / L, or at least 2,000 or greater.

[0139] In some ways, the stream (e.g., biomass) has a concentration of 1,200 mg / L to 90,000 mg / L, e.g., 2,400 mg / L to 90,000 mg / L, 3,600 mg / L to 90,000 mg / L, 4,800 mg / L to 90,000 mg / L, 10,000 mg / L to 90,000 mg / L, 20,000 mg / L to 90,000 mg / L, 30,000 mg / L to 90,000 mg / L, 40,000 mg / L to 90,000 mg / L, 50,000 mg / L to 90,000 mg / L, 60,000 mg / L to 90,000 mg / L, 70,000 mg / L to 90,000 mg / L, and 80,000 mg / L to 90,000 mg / L. It has a solid concentration of mg / L, 1,200 mg / L to 80,000 mg / L, 1,200 mg / L to 70,000 mg / L, 1,200 mg / L to 60,000 mg / L, 1,200 mg / L to 50,000 mg / L, 1,200 mg / L to 40,000 mg / L, 1,200 mg / L to 30,000 mg / L, 1,200 mg / L to 20,000 mg / L, 1,200 mg / L to 10,000 mg / L, 1,200 mg / L to 4,800 mg / L, 1,200 mg / L to 3,600 mg / L, or 1,200 mg / L to 2,400 mg / L.

[0140] In some embodiments, prior to incorporating nanobubbles into the stream (e.g., biomass), the stream has a dissolved oxygen content that is substantially the same as the dissolved oxygen content of the nanobubble-containing stream.

[0141] In some embodiments, the stream (e.g., biomass) has a dry solids content of at least 0.12% by weight, for example, at least 0.25% by weight, at least 0.5% by weight, at least 0.75% by weight, at least 1% by weight, at least 2.0% by weight, at least 2.5% by weight, at least 3.0% by weight, at least 3.5% by weight, at least 4.0% by weight, at least 4.5% by weight, at least 5.0% by weight, at least 5.5% by weight, at least 6.0% by weight, at least 6.5% by weight, at least 7.0% by weight, at least 7.5% by weight, at least 8.0% by weight, at least 8.5% by weight, at least 9.0% by weight, at least 9.5% by weight, at least 10.0% by weight, or more.

[0142] In some aspects, the stream (e.g., biomass) is 0.12% to 4.5% by weight, for example, 0.25% to 4.5% by weight, 0.5% to 4.5% by weight, 0.75% to 4.5% by weight, 1% to 4.5% by weight, 1.5% to 4.5% by weight, 2% to 4.5% by weight, 2.5% to 4.5% by weight, 3% to 4.5% by weight, 3.5% to 4.5% by weight, 4% by weight It has a dry solids content of 1% to 4.5% by weight, 0.12% to 4% by weight, 0.12% to 3.5% by weight, 0.12% to 3% by weight, 0.12% to 2.5% by weight, 0.12% to 2% by weight, 0.12% to 1.5% by weight, 0.12% to 1% by weight, 0.12% to 0.75% by weight, 0.12% to 0.5% by weight, or 0.12% to 0.25% by weight.

[0143] In several aspects, the stream (e.g., biomass) contains at least 2,000 mg / L, for example, at least 5,000 mg / L, at least 25,000 mg / L, at least 50,000 mg / L, at least 75,000 mg / L, at least 100,000 mg / L, at least 250,000 mg / L, at least 500,000 mg / L, at least 750,000 mg / L, at least 1,000,000 mg / L, at least 1,500,000 mg / L, at least 2,000,000 mg / L, at least 2,500,000 mg / L, at least 3,000,000 mg / L, at least 3,500,000 mg / L, at least 4,000,000 mg / L, at least 4,500,000 mg / L, at least 5,000,000 It has a chemical oxygen demand of mg / L or more.

[0144] In some ways, the stream (supply biomass) is 2,000 mg / L to 5,000,000 mg / L, 5,000 mg / L to 5,000,000 mg / L, 25,000 mg / L to 5,000,000 mg / L, 50,000 mg / L to 5,000,000 mg / L, 75,000 mg / L to 5,000,000 mg / L, 100,000 mg / L to 5,000,000 mg / L, 250,000 mg / L to 5,000,000 mg / L, 500,000 mg / L to 5,000,000 mg / L, 750,000 mg / L to 5,000,000 mg / L, and 1,000,000 mg / L to 5,000,000 mg / L. mg / L, 2,000,000 mg / L~5,000,000 mg / L, 3,000,000 mg / L~5,000,000 mg / L, 4,000,000 mg / L~5,000,000 mg / L, 2,000 mg / L~4,000,000 mg / L, 2,000 mg / L~3,000,000 mg / L, 2,000 mg / L~2,000,000 mg / L, 2,000 mg / L~1,000,000 mg / L, 2,000 mg / L~750,000 mg / L, 2,000 mg / L~500,000 mg / L, 2,000 mg / L~250,000 mg / L, 2,000 mg / L~100,000 It has a chemical oxygen demand of mg / L, 2,000 mg / L to 75,000 mg / L, 2,000 mg / L to 50,000 mg / L, 2,000 mg / L to 25,000 mg / L, or 2,000 mg / L to 5,000 mg / L.

[0145] In some embodiments, the stream (e.g., biomass) has a biological oxygen demand of at least 1,000 mg / L, at least 5,000 mg / L, at least 25,000 mg / L, at least 50,000 mg / L, at least 75,000 mg / L, at least 100,000 mg / L, at least 250,000 mg / L, at least 500,000 mg / L, at least 750,000 mg / L, at least 1,000,000 mg / L, at least 1,500,000 mg / L, at least 2,000,000 mg / L, at least 2,500,000 mg / L, or more.

[0146] In some ways, the stream (e.g., biomass) is 1,000 mg / L to 2,500,000 mg / L, for example 5,000 mg / L to 2,500,000 mg / L, 25,000 mg / L to 2,500,000 mg / L, 50,000 mg / L to 2,500,000 mg / L, 75,000 mg / L to 2,500,000 mg / L, 100,000 mg / L to 2,500,000 mg / L, 250,000 mg / L to 2,500,000 mg / L, 500,000 mg / L to 2,500,000 mg / L, 750,000 mg / L to 2,500,000 mg / L, 1,000,000 mg / L to 2,500,000 mg / L mg / L, 1,500,000 mg / L~2,500,000 mg / L, 2,000,000 mg / L~2,500,000 mg / L, 1,000 mg / L~2,000,000 mg / L, 1,000 mg / L~1,500,000 mg / L, 1,000 mg / L~1,000,000 mg / L, 1,000 mg / L~750,000 mg / L, 1,000 mg / L~500,000 mg / L, 1,000 mg / L~250,000 mg / L, 1,000 mg / L~100,000 mg / L, 1,000 mg / L~75,000 mg / L, 1,000 mg / L~50,000 mg / L, 1,000 It has a biological oxygen demand of mg / L to 25,000 mg / L, or 1,000 mg / L to 5,000 mg / L.

[0147] Nanobubbles and nanobubble generators The methods and systems described herein involve the step of generating nanobubbles in biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) using a nanobubble generator. As used herein, the term “nanobubble” refers to a bubble having a diameter smaller than 1 micron. Microbubbles, larger than nanobubbles, are bubbles having a diameter larger than or equal to 1 micron and smaller than 50 microns. Macrobubbles are bubbles having a diameter larger than or equal to 50 microns. As used herein, “nanobubble generator” refers to a device for generating nanobubbles.

[0148] Nanobubbles possess several unique properties, including high gas solubility in liquids due to their high internal pressure and long lifespan in liquids due to their negatively charged surface. Conversely, microbubbles and macrobubbles are larger in size and therefore rise rapidly and burst at the water surface. Thus, in some embodiments, nanobubble-containing sludge contains nanobubbles that are stable in the sludge for at least one month or at least three months under ambient pressure and temperature.

[0149] Any method or apparatus known in the art or described herein may be used to generate nanobubbles in biomass in the methods and systems provided herein. Non-limiting examples of methods and apparatus for generating nanobubbles that may be used in the methods and systems described herein are provided in U.S. Patent Applications No. 10,591,231 and No. 11,331,633; these applications are incorporated herein by reference in their entirety for purposes and subjects referred herein.

[0150] The methods and systems described herein include the step of generating nanobubbles in biomass by flowing sludge into a nanobubble generator. Alternatively or additionally, the methods and systems described herein may include the step of generating nanobubbles in biomass by submerging a nanobubble generator into the biomass.

[0151] The methods and systems described herein include the use of one or more nanobubble generators, such as one, two, three, four, five, six, or more nanobubble generators. The one or more nanobubble generators may be included in the methods and systems described herein as separate modules or in combination with other modules. For example, FIG. 1A shows nanobubble generators 160a - 160d as separate modules of system 100. In another embodiment, one or more nanobubble generators may be included in a solid - liquid separation module, a sludge activation module, a concentrator, an anaerobic reactor, or a combination thereof.

[0152] The nanobubble generator for use in the methods and systems described herein can generate high - concentration nanobubbles in biomass (such as plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof). In some embodiments, the nanobubble generator can generate nanobubbles at a concentration of at least 10 3 per cm 6 . In some embodiments, the nanobubble concentration is at least 10 3 per cm 7 , at least 10 3 per cm 8 , at least 10 3 per cm 9 , at least 10 3 per cm 10 , or at least 10 3 per cm 11 .

[0153] The nanobubble concentration is 1 cm 3 This is expressed as the number of nanobubbles per unit area. The measurement is performed by collecting three samples from a nanobubble generator and analyzing each sample within 20 minutes of acquisition using Nanosight NS3000 analyzer, available from Malvern PANalytical, by Nanoparticle Tracking Analysis. Each sample is filtered using a 0.45 μm filter before analysis with the Nanosight NS3000 analyzer.

[0154] Any gas may be used to generate nanobubbles in biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) according to the methods and systems described herein. Non-limiting examples of gases that may be used to generate nanobubbles include air, hydrogen, biogas, methane, carbon dioxide, nitrogen, argon or other inert gases, oxygen, or ozone.

[0155] The methods and systems described herein involve generating nanobubbles in biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) with little or no detectable increase in the dissolved oxygen content of the sludge. Thus, in some embodiments, the dissolved oxygen content of the biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) is substantially the same as the dissolved oxygen content of the nanobubble-containing sludge.

[0156] In this specification, if there is no detectable difference between the dissolved oxygen content of biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) and that of nanobubble-containing biomass, then the dissolved oxygen content of biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof) is considered "substantially the same" as the dissolved oxygen content of nanobubble-containing biomass. Any method or apparatus, such as a dissolved oxygen (DO) sensor or the Winkler method, may be used to detect the dissolved oxygen content of biomass.

[0157] Anaerobic digestion and anaerobic reactors The methods and systems described herein involve the anaerobic digestion of nanobubble-containing biomass using an anaerobic reactor. As used herein, the term "anaerobic digestion" refers to the process by which microorganisms decompose organic materials such as sludge in the absence or near absence of oxygen to form hydrogen, methane, and other products. As used herein, "anaerobic reactor" refers to a device for performing anaerobic digestion.

[0158] The methods and systems described herein may include one or more anaerobic reactors. Any anaerobic reactor known in the art or described herein may be used in the methods and systems described herein. For example, the anaerobic reactor may be an anaerobic digester, a lagoon (e.g., a facultative lagoon), an upward-flowing anaerobic sludge bed, a tank, or another type of anaerobic reactor. In some embodiments, the anaerobic reactor is configured to process nanobubble-containing sludge. In such cases, the anaerobic reactor may output filtrate and solid digestate.

[0159] Any type of biomass may be digested anaerobically in an anaerobic reactor using the methods and systems described herein. In some embodiments, the methods described herein include the anaerobic digestion of nanobubble-containing biomass (e.g., plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof).

[0160] The biomass for the anaerobic digestion processes described herein may be of any type. For example, the biomass may be biomass derived from forest products or their derivatives, such as wood products such as wood or wood products (e.g., sawdust); paper, pulp, or cardboard; lignin, cellulose, or hemicellulose; or other forest products or their derivatives. The biomass may be biomass of agricultural products, such as biomass of arable crops or grains, such as corn, millet, clover, rapeseed, sunflower, sugarcane, sorghum, flour, or other crop or grain biomass. The biomass may be biomass of agricultural waste, such as straw, fiber, or husks (of rice, corn, or wheat); bagasse, oilseed meal, or grain alcohol distillation wastewater; or other agricultural waste biomass. The biomass may be biomass of food by-products or food waste, such as biomass of starch, sugar, protein, fat, whey, or other food by-products or waste. The biomass may also be animal waste biomass, such as compost sludge or shrimp sludge.

[0161] Various types of anaerobic digesters may be used for the anaerobic digestion processes described herein, including, among many others, mesothermal anaerobic digesters, thermophilic anaerobic digesters, coldophilic anaerobic digesters, single-stage or double-stage anaerobic digesters, batch or continuous anaerobic digesters, wet or dry anaerobic digesters, high-speed or low-speed anaerobic digesters, or adhesive or floating anaerobic digesters.

[0162] Solid-liquid separation module The methods and systems described herein involve a step of separating an input stream into solids and liquids in a solid-liquid separation module. The input stream may include an input stream to a system (e.g., a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system) and / or an output stream from one or more components of that system (e.g., a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system).

[0163] In some embodiments, the solid-liquid separation module comprises a solid-liquid separator for separating solids from liquids. As used herein, the term “solid-liquid separator” refers to a device for separating an input stream to a system (e.g., a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system) and / or an output stream from one or more components of that system (e.g., a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system) into solid and liquid components.

[0164] The methods and systems described herein may include one or more solid-liquid separators. Any solid-liquid separator known in the art or described herein may be used in the methods and systems described herein. Non-limiting examples of methods and apparatus for separating solid and liquid components for use in the methods and systems described herein include clarifiers, chemically enhanced primary treatment, fast clarification, primary effluent filtration, primary filtration, rotary belt filtration, microscreens, dissolved air flotation clarifiers, gravity filtration, or combinations thereof.

[0165] Using the methods and systems described herein, any stream may be separated into solid and liquid in a solid-liquid separator. In some embodiments, the methods described herein include the step of separating a liquid stream of a system (e.g., a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system) into a solid stream, such as sludge (e.g., primary sludge), and a liquid stream. Alternatively or additionally, the methods described herein include the step of separating a liquid stream into a solid stream, such as sludge (e.g., return sludge), and another liquid stream.

[0166] Sludge activation module The methods and systems described herein involve a step of activating sludge using a sludge activation module. As used herein, the term “sludge activation” refers to the process by which organic and inorganic contaminants are converted into suspended biomass in a liquid and separated to produce waste activated sludge and a liquid stream. In some embodiments, sludge activation is carried out under aerobic conditions.

[0167] In some embodiments, the sludge activation module comprises a biological reactor for producing activated sludge (e.g., waste activated sludge, return activated sludge). As used herein, the term “biological reactor” refers to a device for producing activated sludge. In some embodiments, the biological reactor includes an anaerobic zone, an anoxic zone, or both.

[0168] The methods and systems described herein may include one or more biological reactors. Any biological reactor for producing activated sludge, known in the art or described herein, may be used in the methods and systems described herein.

[0169] Using the methods and systems described herein, any input stream may be processed in a biological reactor to become activated sludge. In some embodiments, the methods described herein include the step of processing a liquid stream into waste activated sludge and another liquid stream. Alternatively or additionally, the methods described herein include the steps of returning the activated sludge to the biological reactor; and processing the activated sludge into return activated sludge.

[0170] Biomass concentration The methods and systems described herein involve biomass concentration using a concentrator. As used herein, the term “biomass concentration” refers to a process of increasing the solids concentration and reducing the free water. As used herein, the term “concentrator” refers to a device for concentrating biomass, and includes, but is not limited to, centrifuges, gravity belt concentrators, gravity concentrators, and rotary drum concentrators.

[0171] In some embodiments, the concentrator may be located within the sludge holding tank. Alternatively or additionally, the concentrator may be located within the equalization tank. Thus, in some embodiments, the method described herein includes the step of concentrating biomass in the sludge holding tank, the equalization tank, or both. In some embodiments, the method described herein includes the step of concentrating biomass and generating nanobubbles in the sludge holding tank, the equalization tank, or both.

[0172] The methods and systems described herein may include one or more concentrators. Any concentrator known in the art or described herein may be used in the methods and systems described herein. In some embodiments, the step of concentrating biomass comprises processing the biomass using one or more of dissolved air flotation, centrifuge, gravity belt concentrator, gravity, or rotary drum concentrator. In some embodiments, the step of concentrating biomass comprises generating a solid stream (e.g., sludge) and a liquid stream; and then providing the liquid stream to a separator that separates the sludge from the input. In such cases, the separator may comprise a clarifier, a membrane, or a combination thereof.

[0173] In the methods and systems described herein, any type of biomass may be concentrated. In some embodiments, the methods described herein include a step of concentrating nanobubble-containing biomass. In some embodiments, the methods described herein include a step of concentrating plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof. In some embodiments, the methods described herein include a step of concentrating any type of wastewater sludge, such as primary sludge, activated sludge, return sludge, or a combination thereof.

[0174] The specific aspects of the subject matter have been described above. Other aspects are also within the scope of the attached claims.

Claims

1. A step of generating nanobubbles in a stream of a system in order to generate a nanobubble-containing stream, wherein the stream has a solid concentration of at least 1,200 mg / L; and A process of processing the nanobubble-containing stream in the anaerobic reactor of the system. A method that includes the following.

2. The method according to claim 1, wherein the dissolved oxygen content of the stream is substantially the same as the dissolved oxygen content of the nanobubble-containing stream.

3. The method according to claim 1, wherein the stream has a solid content concentration of 1,200 mg / L to 90,000 mg / L.

4. The method according to claim 1, wherein the stream has a dry solids content of at least 0.12% by weight.

5. The method according to claim 1, wherein the stream has a dry solids content of 0.12% to 4.5% by weight.

6. The method according to claim 1, wherein the gas is selected from air, argon, hydrogen, biogas, methane, carbon dioxide, nitrogen, oxygen, or ozone.

7. The method according to claim 1, wherein the stream contains biomass.

8. The method according to claim 7, wherein the biomass includes plant biomass, animal biomass, agricultural biomass, wastewater sludge, or a combination thereof.

9. The method according to claim 1, wherein the system comprises at least one nanobubble generator.

10. The method according to claim 1, wherein the system is a wastewater treatment system, an energy production system, a fertilizer production system, or an anaerobic fermentation system.

11. The method according to claim 1, wherein the system is a wastewater treatment system and the stream includes wastewater sludge.

12. A step of generating nanobubbles in a stream of a system in order to generate a nanobubble-containing stream, wherein the stream has a chemical oxygen demand of at least 2,000 mg / L and / or the stream has a biological oxygen demand of at least 1,000 mg / L; and A process of processing the nanobubble-containing stream in the anaerobic reactor of the system. A method that includes the following.

13. The method according to claim 12, wherein the stream has a chemical oxygen demand of 2,000 mg / L to 5,000,000 mg / L.

14. The method according to claim 12, wherein the stream has a biological oxygen demand of 1,000 mg / L to 2,500,000 mg / L.

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