Anaerobic treatment system and process suitable for high organic suspended solids containing wastewater

Abstract

The application discloses an anaerobic treatment system and process suitable for wastewater containing high organic suspended matter, which comprises a water inlet assembly, a reactor, an internal circulation assembly, a water collecting and discharging assembly and an exhaust assembly; a group of metal membrane tubes are arranged in the reactor, and hydrolytic acid-producing bacteria are loaded in the metal membrane tubes; methanogenic bacteria are filled in the space outside the metal membrane tubes in the reactor; the reactor is connected with the water inlet assembly through the bottom of the metal membrane tubes; the internal circulation assembly is connected with the upper and lower parts of the reactor respectively; the water collecting and discharging assembly is arranged on the top of the reactor, and the reaction water is discharged from the reactor through a discharging pipeline; and the exhaust assembly is connected with the top of the reactor. The application can realize the effect that the acid-producing phase and the methanogenic phase are separated from each other and cooperate with each other, the effluent water is filtered through a membrane, and stable three-phase separation is realized. The application has the advantages of high anaerobic reaction efficiency, stable effluent water quality and high methane yield, and is especially suitable for anaerobic treatment of wastewater containing high organic suspended matter.

Description

An anaerobic treatment system and process suitable for wastewater containing high levels of organic suspended solids. Technical Field

[0001] This invention pertains to wastewater treatment technology, specifically relating to an anaerobic treatment system and process suitable for wastewater containing high levels of organic suspended solids. Background Technology

[0002] The methanogenesis process in microbial communities can be divided into four steps: fermentation, acid production, acetogenesis, and methanogenesis. Fermentation and acid production are carried out by fermentative bacteria, which hydrolyze large polymer molecules such as proteins and polysaccharides into their corresponding monomers, and then ferment these monomers into smaller molecules such as volatile fatty acids and alcohols. Acetogenesis is mainly carried out by acetotrophic bacteria, which further decompose the smaller molecules produced in the previous process into formic acid, acetic acid, hydrogen, and CO2. Methanogenesis is carried out by methanogenic archaea, which use formic acid, acetic acid, hydrogen, and CO2 as substrates to synthesize methane. However, the methanogenesis process in microbial communities is not a simple matter transfer. The degradation of organic acids or alcohols by acetotrophic bacteria is an endothermic process under standard conditions and cannot occur spontaneously. Methanogenic archaea can utilize their degradation products to drive the chemical equilibrium towards the product. The cooperative relationship between acetotrophic bacteria and methanogenic archaea is called mutualism, and this process is also the rate-limiting step in methane release. Summary of the Invention

[0003] The first objective of this invention is to address the shortcomings of existing technologies by providing an anaerobic treatment system suitable for wastewater containing high levels of organic suspended solids, which achieves spatial separation of acid-producing bacteria and methanogenic bacteria while maintaining their cooperation in electron transfer, thereby improving methanogenic efficiency and organic matter removal efficiency.

[0004] The second objective of this invention is to provide an anaerobic treatment process suitable for wastewater containing high levels of organic suspended solids, thereby improving the organic matter degradation efficiency and methane yield.

[0005] To achieve the first objective mentioned above, the technical solution adopted by the present invention is as follows:

[0006] An anaerobic treatment system suitable for wastewater containing high levels of organic suspended solids includes an influent component, a reactor, an internal circulation component, a water collection and discharge component, and an exhaust component. The reactor contains a set of metal membrane tubes loaded with hydrolytic acid-producing bacteria, and the space outside the metal membrane tubes within the reactor is filled with methanogenic bacteria. The reactor is connected to the influent component via the bottom of the metal membrane tubes. The two ends of the internal circulation component are connected to the upper and lower parts of the reactor, respectively. The water collection and discharge component is located at the top of the reactor and discharges the effluent from the reactor through an exhaust pipe. The exhaust component is connected to the top of the reactor.

[0007] Wastewater comes into contact with hydrolytic acidifying bacteria within the metal membrane tubes, undergoing a hydrolysis and acidification reaction that degrades suspended solids and large organic molecules into smaller molecules. The wastewater containing these smaller dissolved organic molecules then permeates through the metal membrane tubes into the space between the reactor shell and the membrane tubes under the pressure of a circulating pump. Within this space, the wastewater containing small organic acids comes into contact with methanogenic bacteria, producing gases such as methane and carbon dioxide, thus decomposing the organic matter in the wastewater. The decomposed wastewater and methane are then separated at the top of the reactor.

[0008] Specifically, the reactor includes a reactor shell and a set of metal membrane tubes disposed inside the reactor shell; a set of water distribution branch pipes are provided on the bottom side of the reactor shell, the outer end of the water distribution branch pipes is connected to the water inlet assembly, and the inner end is connected to the bottom of the corresponding metal membrane tube; the metal membrane tubes are conductive stainless steel membrane tubes, and the membrane tube pore size is between 100μm and 0.01μm, preferably between 0.05μm and 0.5μm.

[0009] Furthermore, a set of liquid collecting pipes is provided on the upper side of the reactor shell, the inner end of the liquid collecting pipes is connected to the top of the corresponding metal membrane tube, and the outer end is connected to the acidification liquid circulation pipe; the outer end of the acidification liquid circulation pipe is connected to the water inlet assembly.

[0010] Specifically, the water collection and discharge assembly includes an ultrafiltration membrane, a membrane water collection pipe, a suction pump, a suction pipe, and an outlet tank; the ultrafiltration membrane is located at the top of the reactor, above the metal membrane tube and the internal circulation assembly, and is selected from any one of flat sheet membranes, hollow fiber membranes, or tubular membranes; the feed liquid inside the reactor and the membrane water collection pipe are located on opposite sides of the ultrafiltration membrane; the membrane water collection pipe is connected to the outlet tank outside the reactor via the suction pipe; and the suction pump is mounted on the suction pipe.

[0011] Specifically, the internal circulation assembly includes an internal circulation pipe, an internal circulation water collection pipe, and an internal circulation pump. The internal circulation pipe is located outside the reactor, with one end connected to the bottom of the reactor and the other end connected to the internal circulation water collection pipe located inside the reactor. The internal circulation water collection pipe is positioned above the metal membrane tube, and a set of permeable holes are evenly distributed on the internal circulation water collection pipe, with a hole diameter between 0.5 and 10 mm. The internal circulation pump is mounted on the internal circulation pipe. Part of the wastewater after methane production is collected through the internal circulation water collection pipe and, under the action of the internal circulation pump, flows back into the reactor through the internal circulation pipe.

[0012] Furthermore, an vent pipe and a vent valve are also provided below the connection between the internal circulation pipe and the bottom of the reactor.

[0013] Specifically, the water inlet assembly includes a water inlet pipe, a water inlet tank, and a water inlet distribution pipe connected in sequence; a water inlet pump pipe is also provided between the water inlet tank and the water inlet distribution pipe, and a water inlet pump is installed on the water inlet pump pipe; the water inlet distribution pipe is connected to the reactor. During equipment operation, one or more fermentation bacteria and hydrolysis bacteria can be added to the water inlet tank, and a stirring system is provided.

[0014] Specifically, the exhaust assembly includes an exhaust pipe, one end of which is connected to the top of the reactor, and the other end is discharged externally or connected to a subsequent exhaust gas treatment system.

[0015] Anaerobic sludge and necessary biostimulants can be added to the reactor during operation. Biostimulants include one or more of activated carbon, iron(III) oxide, ferric oxide, graphene, polyaniline, and polypyrrole. Biological packing materials can be added to the metal membrane tubes if necessary.

[0016] To achieve the second objective mentioned above, the present invention also provides a process for treating wastewater containing high levels of organic suspended solids using the above-described system, comprising the following steps:

[0017] S1: The wastewater to be treated is fed into the reactor through the inlet component, and hydrolytic acid-producing bacteria are added during the wastewater inlet process and mixed evenly;

[0018] S2: Inject anaerobic sludge containing methanogens into the reactor, so that the external space of the metal membrane tube is filled with methanogens, and the anaerobic sludge contains small granular activated carbon and iron oxide powder.

[0019] S3: Start the inlet water component and the internal circulation component to send the wastewater mixed with hydrolytic acid-producing bacteria into the metal membrane tube for hydrolysis and acidification reaction, degrading suspended solids and large molecular organic matter into small molecules; the wastewater containing small molecule dissolved organic matter seeps into the external space of the metal membrane tube under the action of the internal circulation component and comes into contact with methanogenic bacteria for further decomposition, producing methane and carbon dioxide gas;

[0020] S4: After multiple cycles, the organic matter is effectively hydrolyzed. The exhaust component is opened to release the gas, and the waste liquid after the reaction is collected by the water collection and discharge component and discharged from the reactor.

[0021] Furthermore, a set of liquid collecting pipes is provided on the upper side of the reactor shell. The inner end of the liquid collecting pipe is connected to the top of the corresponding metal membrane tube, and the outer end is connected to the acidification liquid circulation pipe. The outer end of the acidification liquid circulation pipe is connected to the water inlet assembly. The acidification liquid obtained from the reaction in the metal membrane tube is led out through the acidification liquid circulation pipe and mixed with the wastewater to be treated outside the reactor.

[0022] Beneficial effects:

[0023] (1) The system of this invention separates the acid-producing phase and the methanogenic phase through a metal membrane, achieving two-phase separation. Both types of bacteria can survive in their respective suitable habitats, avoiding competition and improving treatment efficiency. The conductivity of the metal membrane enables effective direct interspecies electron transfer between the acid-producing and methanogenic bacteria, achieving mutualistic symbiosis and effectively improving methanogenic efficiency. The semi-permeable nature of the metal membrane retains large molecules and suspended organic matter within the system. If necessary, fermentation bacteria and a stirring system can be added to the inlet tank to further promote the fermentation and degradation of proteins and colloidal organic matter. The generated scum and other non-degradable substances can be easily removed from the inlet tank, preventing them from crowding out the biochemical degradation space. Meanwhile, small-molecule organic acids and other organic matter easily utilized by methanogenic bacteria can pass through the microfiltration or ultrafiltration membrane pores and enter the methanogenic zone. Conventional anaerobic reactors inevitably introduce recalcitrant macromolecular organic matter, colloids, and suspended organic matter into the methanogenic zone, leading to pH fluctuations and difficulties in the utilization of macromolecules by methanogenic bacteria. This results in low methanogenic efficiency and unstable operation. This proposed solution utilizes the semi-permeable nature of a metal membrane to separate degradation products, achieving the goal of using specific bacterial strains with specific substrates, thereby significantly improving reaction efficiency.

[0024] (2) This invention integrates an anaerobic membrane system, which can effectively retain methanogens inside the reactor, significantly increasing the number of methanogens and indirectly improving the reactor's ability to degrade organic matter. The treatment process is flexible in operation; if necessary, anaerobic biological packing materials and conductive carriers (such as activated carbon and iron tetroxide) can be added inside the reactor to further improve the interspecies electron transfer effect and methanogenic capacity of microorganisms. This reactor has the advantages of high anaerobic reaction efficiency, stable effluent quality, and high methane yield, and is especially suitable for the anaerobic treatment of wastewater containing high levels of suspended organic matter. Attached Figure Description

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0026] Figure 1 is a schematic diagram of the overall structure of the high-efficiency reactor of the present invention.

[0027] Figure 2 is a cross-sectional view (AA) of the reactor of the present invention.

[0028] Figure 3 is a BB cross-sectional view of the reactor of the present invention.

[0029] Figure 4 is a CC cross-sectional view of the reactor of the present invention.

[0030] The reference numerals in the attached figures represent:

[0031] 1-Inlet pipe; 2-Inlet tank; 3-Inlet pump pipe; 4-Inlet pump; 5-Inlet distribution pipe; 6-Distribution branch pipe; 7-Reactor casing; 8-Metal membrane tube; 9-Collection pipe; 10-Acidification liquid circulation pipe; 11-Internal circulation pump; 12-Internal circulation pipe; 13-Internal circulation collection pipe; 14-Ultrafiltration membrane; 15-Membrane collection pipe; 16-Suction pump; 17-Suction pipe; 18-Outlet tank; 19-Exhaust pipe; 20-Drain pipe; 21-Agitator. Detailed Implementation

[0032] The present invention can be better understood from the following embodiments.

[0033] As shown in Figure 1, this invention is applicable to an anaerobic treatment system for wastewater containing high levels of organic suspended solids, comprising an influent component, a reactor, an internal circulation component, a water collection and discharge component, and an exhaust component. The reactor contains a set of metal membrane tubes 8, which are loaded with hydrolytic acid-producing bacteria. Methanogenic bacteria are also present in the space outside the metal membrane tubes 8 within the reactor. The reactor is connected to the influent component via the bottom of the metal membrane tubes 8. The two ends of the internal circulation component are connected to the upper and lower parts of the reactor, respectively. The water collection and discharge component is located at the top of the reactor and discharges the effluent from the reactor through an exhaust pipe. The exhaust component is connected to the top of the reactor.

[0034] Wastewater comes into contact with hydrolytic acidifying bacteria within the metal membrane tubes, undergoing a hydrolysis and acidification reaction that degrades suspended solids and large organic molecules into smaller molecules. The wastewater containing these smaller dissolved organic molecules then permeates through the metal membrane tubes into the space between the reactor shell and the membrane tubes under the pressure of a circulating pump. Within this space, the wastewater containing small organic acids comes into contact with methanogenic bacteria, producing gases such as methane and carbon dioxide, thus decomposing the organic matter in the wastewater. The decomposed wastewater and methane are then separated at the top of the reactor.

[0035] Referring to Figures 2 to 4, the reactor of the present invention includes a reactor shell 7 and a set of metal membrane tubes 8 disposed inside the reactor shell 7; a set of water distribution branch pipes 6 are provided on the bottom side of the reactor shell 7, the outer end of the water distribution branch pipes 6 is connected to the water inlet assembly, and the inner end is connected to the bottom of the corresponding metal membrane tube 8; the metal membrane tube 8 is a conductive stainless steel membrane tube, and the membrane tube pore size is between 100μm and 0.01μm, preferably between 0.05μm and 0.5μm.

[0036] A set of liquid collecting pipes 9 are provided on the upper side of the reactor casing 7. The inner end of the liquid collecting pipe 9 is connected to the top of the corresponding metal membrane tube 8, and the outer end is connected to the acidification liquid circulation pipe 10. The outer end of the acidification liquid circulation pipe 10 is connected to the water inlet assembly. The acidification liquid obtained from the reaction in the metal membrane tube 8 is led out through the acidification liquid circulation pipe 10, mixed with the wastewater to be treated outside the reactor, and then sent back into the reactor.

[0037] The water collection and discharge assembly includes an ultrafiltration membrane 14, a membrane water collection pipe 15, a suction pump 16, a suction pipe 17, and an outlet tank 18. The ultrafiltration membrane 14 is located at the top of the reactor and above the metal membrane tube 8 and the internal circulation assembly. The ultrafiltration membrane is selected from any one of flat sheet membranes, hollow fiber membranes, or tubular membranes. The feed liquid inside the reactor and the membrane water collection pipe 15 are located on opposite sides of the ultrafiltration membrane 14. The membrane water collection pipe 15 is connected to the outlet tank 18 outside the reactor through the suction pipe 17. The suction pump 16 is installed on the suction pipe 17.

[0038] The internal circulation assembly includes an internal circulation pipe 12, an internal circulation water collection pipe 13, and an internal circulation pump 11. The internal circulation pipe 12 is located outside the reactor, with one end connected to the bottom of the reactor and the other end connected to the internal circulation water collection pipe 13 located inside the reactor. The internal circulation water collection pipe 13 is positioned above the metal membrane tube 8, and a set of permeable holes are evenly distributed on the internal circulation water collection pipe 13, with a hole diameter between 0.5 and 10 mm. The internal circulation pump 11 is mounted on the internal circulation pipe 12. Part of the wastewater after methane production is collected through the internal circulation water collection pipe and, under the action of the internal circulation pump, flows back into the reactor through the internal circulation pipe.

[0039] Below the connection between the internal circulation pipe 12 and the bottom of the reactor, there is also an vent pipe 20 and a vent valve.

[0040] The water assembly includes an inlet pipe 1, an inlet tank 2, and an inlet distribution pipe 5 connected in sequence; an inlet pump pipe 3 is also provided between the inlet tank 2 and the inlet distribution pipe 5, and an inlet pump 4 is installed on the inlet pump pipe 3; the inlet distribution pipe 5 is connected to the reactor. During operation, one or more fermentation bacteria and hydrolysis bacteria can be added to the inlet tank 2, and a mixer 21 is provided.

[0041] The exhaust assembly includes an exhaust pipe 19, one end of which is connected to the top of the reactor, and the other end is either discharged externally or connected to a subsequent exhaust gas treatment system.

[0042] Anaerobic sludge and necessary biostimulants can be added to the reactor during operation. Biostimulants include one or more of activated carbon, iron(III) oxide, ferric oxide, graphene, polyaniline, and polypyrrole. Biological packing materials can be added to the metal membrane tubes if necessary.

[0043] In operation, the liquid in the inlet tank 2 is pumped through the inlet pump pipe 3 and then through the inlet distribution pipe 5 by the inlet pump 4, entering the distribution branch pipes 6 and then the metal membrane tube 8. The metal membrane tube 8 is filled with hydrolytic bacteria. The wastewater comes into contact with the hydrolytic acid-producing bacteria, causing a hydrolysis reaction. The small-molecule organic acids produced by hydrolysis can permeate through the metal membrane and enter the methanogenic zone between the reactor shell 6 and the metal membrane tube 8. Before operation, granular sludge containing methanogenic bacteria can be injected into the methanogenic zone through the drain pipe 20. The organic acids and small-molecule organic matter entering the methanogenic zone come into contact with the methanogenic bacteria and undergo further degradation, converting the organic matter into methane and carbon dioxide. Simultaneously, the hydrolytic bacteria in the metal membrane tube 8 and the methanogenic bacteria in the methanogenic zone undergo direct interspecies electron transfer through the metal membrane tube 8, achieving symbiotic relations between the two types of bacteria. This greatly improves the organic matter degradation efficiency and methane yield. Wastewater in the methanogenic zone is further decomposed by methanogenic bacteria and then separated at the top of the zone by an ultrafiltration membrane 14. The methanogenic bacteria remain inside the reactor, while the purified water permeates through the ultrafiltration membrane 14 and enters the membrane collection pipe 15. Finally, it is discharged into the effluent tank 18 by the suction pump 16. The generated methane gas is discharged through the exhaust pipe 19.

[0044] This invention provides an anaerobic treatment system and process suitable for wastewater containing high levels of organic suspended solids. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. An anaerobic treatment system suitable for wastewater containing high levels of organic suspended solids, characterized in that, The reactor includes an inlet assembly, a reactor, an internal circulation assembly, a water collection and discharge assembly, and an exhaust assembly. The reactor contains a set of metal membrane tubes (8), which are loaded with hydrolytic acid-producing bacteria. Methanogenic bacteria are also present in the space outside the metal membrane tubes (8) within the reactor. The reactor is connected to the inlet assembly via the bottom of the metal membrane tubes (8). The two ends of the internal circulation assembly are connected to the upper and lower parts of the reactor, respectively. The water collection and discharge assembly is located at the top of the reactor and discharges the effluent from the reactor through an exhaust pipe. The exhaust assembly... The reactor is connected to the top of the reactor; the reactor includes a reactor shell (7) and a set of metal membrane tubes (8) disposed inside the reactor shell (7); a set of water distribution branch pipes (6) are provided on the bottom side of the reactor shell (7), the outer end of the water distribution branch pipe (6) is connected to the water inlet assembly, and the inner end is connected to the bottom of the corresponding metal membrane tube (8); the metal membrane tube (8) is a conductive stainless steel membrane tube with a pore size between 100μm and 0.01μm; the water inlet assembly includes a water inlet pipe (1), a water inlet tank (2) and a water inlet distribution pipe (1) connected in sequence. 5); A water inlet pump pipe (3) is also provided between the water inlet tank (2) and the water inlet distribution pipe (5), and a water inlet pump (4) is provided on the water inlet pump pipe (3); The water inlet distribution pipe (5) is connected to the reactor; A set of liquid collection pipes (9) is provided on the upper side of the reactor shell (7), the inner end of the liquid collection pipe (9) is connected to the top of the corresponding metal membrane pipe (8), and the outer end is connected to the acidification liquid circulation pipe (10); The outer end of the acidification liquid circulation pipe (10) is connected to the water inlet assembly; The water collection and discharge assembly includes an ultrafiltration membrane (14) and a membrane water collection pipe (1 5) Suction pump (16), suction pipe (17) and outlet tank (18); The ultrafiltration membrane (14) is located at the top of the reactor and above the metal membrane tube (8) and the internal circulation component. The ultrafiltration membrane is selected from any one of flat sheet membrane, hollow fiber membrane or tubular membrane; The feed liquid inside the reactor and the membrane water collection pipe (15) are located on both sides of the ultrafiltration membrane (14); The membrane water collection pipe (15) is connected to the outlet tank (18) outside the reactor through the suction pipe (17); The suction pump (16) is installed on the suction pipe (17).

2. The anaerobic treatment system for wastewater containing high levels of suspended organic matter according to claim 1, characterized in that, The internal circulation assembly includes an internal circulation pipe (12), an internal circulation water collection pipe (13), and an internal circulation pump (11). The internal circulation pipe (12) is located outside the reactor, with one end connected to the bottom of the reactor and the other end connected to the internal circulation water collection pipe (13) located inside the reactor. The internal circulation water collection pipe (13) is positioned above the metal membrane pipe (8), and a set of permeable holes are evenly distributed on the internal circulation water collection pipe (13), with the permeable hole diameter between 0.5 and 10 mm. The internal circulation pump (11) is positioned on the internal circulation pipe (12).

3. The anaerobic treatment system for wastewater containing high levels of suspended organic matter according to claim 2, characterized in that, Below the connection between the internal circulation pipe (12) and the bottom of the reactor, there is also an vent pipe (20) and a vent valve.

4. The anaerobic treatment system for wastewater containing high levels of suspended organic matter according to claim 1, characterized in that, The exhaust assembly includes an exhaust pipe (19), one end of which is connected to the top of the reactor, and the other end is discharged externally or connected to a subsequent exhaust gas treatment system.

5. The process for treating wastewater containing high levels of suspended organic matter using the system described in claim 1, characterized in that, The process includes the following steps: S1: The wastewater to be treated is fed into the reactor through the inlet component, and hydrolytic acid-producing bacteria are added during the wastewater inlet process and mixed evenly; S2: Anaerobic sludge containing methanogenic bacteria is injected into the reactor, so that the external space of the metal membrane tube (8) is filled with methanogenic bacteria, and the anaerobic sludge contains small granular activated carbon and iron oxide powder; S3: The inlet component and the internal circulation component are started, and the wastewater mixed with hydrolytic acid-producing bacteria is sent into the metal membrane tube (8) for hydrolysis and acidification reaction, which degrades suspended solids and large molecular organic matter into small molecules; the wastewater containing small molecule dissolved organic matter seeps into the external space of the metal membrane tube (8) under the action of the internal circulation component and comes into contact with the methanogenic bacteria for further decomposition, producing methane and carbon dioxide gas; S4: After multiple cycles, the organic matter is effectively hydrolyzed. The exhaust component is opened to release the gas, and the waste liquid after the reaction is collected by the water collection and discharge component and discharged from the reactor.

6. The process for treating wastewater containing high levels of suspended organic matter according to claim 5, characterized in that, A set of liquid collection pipes (9) are provided on the upper side of the reactor shell (7). The inner end of the liquid collection pipe (9) is connected to the top of the corresponding metal membrane tube (8), and the outer end is connected to the acidification liquid circulation pipe (10). The outer end of the acidification liquid circulation pipe (10) is connected to the water inlet assembly. The acidification liquid obtained from the reaction in the metal membrane tube (8) is drawn out through the acidification liquid circulation pipe (10) and mixed with the wastewater to be treated outside the reactor.

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