An integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus

Abstract

This utility model relates to the field of wastewater treatment and resource recovery technology, specifically disclosing an integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus, including: an anaerobic fermentation unit, a phosphorus recovery unit, a sludge treatment unit, a biogas recovery unit, a dosing unit, and a PLC control device. In this integrated device, after the phosphorus-rich supernatant released from the anaerobic fermentation unit enters the sedimentation tank, the PLC control device adjusts the pH to 8.5-9.0 according to data from a pH monitor, using a sodium hydroxide dosing machine, while simultaneously adding magnesium chloride via a magnesium chloride dosing machine. 2+ , prompting PO4 3‑ NH4 + With Mg 2+ The reaction produces struvite, which is then accelerated by adding PAM through a PAM dosing machine. Finally, the struvite is collected and dried through an inclined tube, realizing the targeted recovery and resource utilization of phosphorus in sludge. This avoids eutrophication of water bodies caused by phosphorus discharge with sludge and significantly improves the utilization rate of phosphorus resources.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment and resource recycling technology, specifically an integrated device for biogas production and phosphorus recovery from anaerobic fermentation of sludge. Background Technology

[0002] During the operation of wastewater treatment and aquaculture industries, a large amount of sludge containing high concentrations of organic matter, nitrogen and phosphorus nutrients, and pathogenic microorganisms is generated. If this sludge is not properly treated, it will not only cause serious environmental pollution but also lead to a huge waste of resources. Currently, traditional treatment methods for this type of sludge mainly include aerobic composting and direct return to the field. However, these methods have obvious limitations. Among them, the waste of phosphorus resources is particularly prominent. More than 90% of the phosphorus in sludge exists in dissolved or particulate form. The phosphorus in the sludge generated after traditional chemical precipitation treatment cannot be effectively recovered, and resource utilization cannot be achieved. It is also easy to cause eutrophication of water bodies. At the same time, most of the biogas produced during the anaerobic fermentation of sludge in China is not effectively utilized and is mostly directly emitted, resulting in a huge waste of energy.

[0003] Existing equipment often has a single function and cannot simultaneously achieve the synergistic process of anaerobic fermentation of sludge to produce biogas and phosphorus recovery. Multiple sets of equipment are required to work together, which increases the complexity and difficulty of operation. It also results in a large footprint and high site requirements, making it unsuitable for use in space-constrained scenarios. Furthermore, the operating costs of multiple devices are relatively high, and the complex structural design increases expenses for equipment maintenance, energy consumption, and other aspects. Utility Model Content

[0004] The purpose of this invention is to provide an integrated device for biogas production and phosphorus recovery from anaerobic fermentation of sludge, in order to solve the problems mentioned in the background art, such as the ineffective recovery and resource utilization of phosphorus in sludge produced by traditional chemical precipitation methods, which easily leads to eutrophication of water bodies, and the fact that most of the biogas produced by anaerobic fermentation in China is not effectively utilized and is mostly directly emitted, resulting in energy waste.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus, comprising an anaerobic fermentation mechanism, a phosphorus recovery mechanism, a sludge treatment mechanism, a biogas recovery mechanism, a dosing mechanism, and a PLC control device. The anaerobic fermentation mechanism includes a mixer, an inclined tube, and a three-phase separator installed on the biogas digester, as well as a biogas monitor, a pH monitor, an ORP monitor, and a temperature monitor for monitoring the biogas digester.

[0006] The biogas recovery mechanism includes a gas storage tank, which collects biogas from the biogas digester;

[0007] The dosing mechanism includes a sodium hydroxide dosing machine, a magnesium chloride dosing machine, and a PAM agent dosing machine;

[0008] The phosphorus recovery mechanism includes a sedimentation tank connected to the biogas digester, and a stirrer 1 and a stirrer 2 are installed on one side of the sedimentation tank. There is also an inclined tube 2 above the sedimentation tank, as well as a pH monitor 2 and an ORP monitor 2 for monitoring the pH value and ORP value inside the sedimentation tank.

[0009] The sludge treatment facility includes a sludge tank connecting a biogas digester and a sedimentation tank, and the sludge tank is connected in sequence to a screw pump and a screw press.

[0010] The PLC control equipment is connected to the equipment in the anaerobic fermentation unit, phosphorus recovery unit, sludge treatment unit, biogas recovery unit, and chemical dosing unit via electrical signals.

[0011] By adopting the above technical solution, anaerobic fermentation, phosphorus recovery, sludge treatment, biogas recovery, chemical dosing and PLC control are integrated into one unit, realizing the coordinated operation of each mechanism, simplifying the equipment structure, reducing the footprint, and improving the processing efficiency through fully automated control.

[0012] Preferably, the phosphorus-rich supernatant outlet of the anaerobic fermentation unit is connected to the inlet of the sedimentation tank, and the residual sludge outlets of both the anaerobic fermentation unit and the phosphorus recovery unit are connected to the inlet of the sludge tank.

[0013] By adopting the above technical solution, the connection relationship between the anaerobic fermentation unit, the phosphorus recovery unit, and the sludge treatment unit is clarified, ensuring that the phosphorus-rich supernatant is directed into the phosphorus recovery unit and the excess sludge is centrally sent to the sludge treatment unit, thus ensuring the continuity of phosphorus recovery and sludge treatment and improving resource recovery and treatment efficiency.

[0014] Preferably, the gas storage tank is installed on one side of the biogas digester, and biogas is supplied to the gas storage tank through a pipeline. The biogas outlet of the three-phase separator is connected to the inlet of the gas storage tank.

[0015] By adopting the above technical solution, the biogas can be effectively collected and stored by connecting the three-phase separator with the gas storage tank, avoiding energy waste caused by direct biogas emission and realizing the energy utilization of biogas.

[0016] Preferably, the reagent outlet of the sodium hydroxide dosing machine is connected to the reagent inlet of the anaerobic fermentation unit and the phosphorus recovery unit.

[0017] Using the above technical solution, the sodium hydroxide dosing machine can selectively add chemicals to the anaerobic fermentation unit and the phosphorus recovery unit, precisely adjusting the pH value at both locations to provide a suitable reaction environment for anaerobic fermentation and phosphorus recovery, ensuring efficient reaction.

[0018] Preferably, the reagent outlets of the magnesium chloride dosing machine and the PAM reagent dosing machine are both connected to the reagent inlet of the agitator of the phosphorus recovery mechanism.

[0019] Using the above technical solution, the magnesium chloride dosing machine and the PAM reagent dosing machine can accurately provide the substances required for the reaction at the appropriate stage, promote the formation and precipitation of struvite, and improve the phosphorus recovery efficiency.

[0020] Preferably, a pH monitor is installed in the sedimentation area where the agitator is located.

[0021] By adopting the above technical solution, a pH monitor is installed in the area where the agitator is located. This allows for real-time monitoring of the pH value in the key areas of phosphorus recovery, providing accurate data for dosing adjustments and ensuring stable phosphorus recovery reaction conditions.

[0022] Preferably, the inlet of the screw pump is connected to the outlet of the sludge tank, and the outlet of the screw pump is connected to the inlet of the screw press.

[0023] By adopting the above technical solution, the connection between the screw pump, sludge tank, and screw press is clearly defined, ensuring that the remaining sludge is transported to the screw press for dewatering in an orderly manner, facilitating the off-site transportation and treatment of sludge, achieving sludge reduction, and lowering treatment costs.

[0024] Compared with the prior art, the beneficial effects of this utility model are: the integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus:

[0025] 1. After the phosphorus-rich supernatant released by the anaerobic fermentation mechanism enters the sedimentation tank, the PLC control equipment adjusts the pH to 8.5-9.0 according to the data from pH monitor 2, while the magnesium chloride dosing machine simultaneously adds Mg. 2+ , prompting PO4 3 -、NH4 + With Mg 24 The reaction produces struvite, which is then accelerated by adding PAM through a PAM dosing machine. Finally, the struvite is collected and dried through an inclined tube, realizing the targeted recovery and resource utilization of phosphorus in sludge. This avoids eutrophication of water bodies caused by phosphorus discharge with sludge and greatly improves the utilization rate of phosphorus resources.

[0026] 2. This device establishes a complete biogas recovery system through the close cooperation between the anaerobic fermentation unit and the biogas recovery unit. The biogas produced during anaerobic fermentation is separated by a three-phase separator, monitored in real time by a biogas monitor, and then transported through pipelines to a gas storage tank for storage. This structural design converts biogas that would otherwise be directly emitted into usable energy, achieving energy recovery and reuse, conforming to the concepts of energy conservation, emission reduction, and resource recycling, and avoiding energy waste.

[0027] 3. This device integrates the anaerobic fermentation mechanism, phosphorus recovery mechanism, and sludge treatment mechanism into a single integrated design. Combined with the fully automated control of the PLC control equipment, the various mechanisms are linked through pipelines and components, reducing energy consumption and material loss in intermediate links. At the same time, the integrated structure significantly reduces the equipment footprint and lowers operating and maintenance costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the integrated device for anaerobic fermentation of livestock wastewater sludge to produce biogas and recover phosphorus.

[0029] In the diagram: 1. Mixer; 2. Inclined tube one; 3. Three-phase separator; 4. Gas storage tank; 5. Sodium hydroxide dosing machine; 6. Magnesium chloride dosing machine; 7. PAM dosing machine; 8. Mixer one; 9. Mixer two; 10. Inclined tube two; 11. Sedimentation tank; 12. Sludge tank; 13. Screw pump; 14. Screw press; 15. Biogas monitor; 16. pH monitor one; 17. ORP monitor one; 18. Temperature monitor; 19. pH monitor two; 20. ORP monitor two. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] Please see Figure 1 This utility model provides a technical solution: an integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus, including a mixer 1, an inclined tube 2, a three-phase separator 3, a gas storage tank 4, a sodium hydroxide dosing machine 5, a magnesium chloride dosing machine 6, a PAM dosing machine 7, a mixer 1 8, a mixer 2 9, an inclined tube 2 10, a sedimentation tank 11, a sludge tank 12, a screw pump 13, a screw press 14, a biogas monitor 15, a pH monitor 1 16, an ORP monitor 1 17, a temperature monitor 18, a pH monitor 2 19, and an ORP monitor 2 20;

[0032] The system includes an anaerobic fermentation unit, a phosphorus recovery unit, a sludge treatment unit, a biogas recovery unit, a dosing unit, and a PLC control device. The anaerobic fermentation unit includes a mixer 1, an inclined tube 2, and a three-phase separator 3 installed on the biogas digester, as well as a biogas monitor 15, a pH monitor 16, an ORP monitor 17, and a temperature monitor 18 for monitoring the biogas digester. The phosphorus-rich supernatant outlet of the anaerobic fermentation unit is connected to the inlet of the sedimentation tank 11. The residual sludge outlets of both the anaerobic fermentation unit and the phosphorus recovery unit are connected to the inlet of the sludge tank 12.

[0033] The biogas recovery mechanism includes a gas storage tank 4, which collects biogas from the biogas digester. The gas storage tank 4 is installed on one side of the biogas digester, and biogas is delivered to the gas storage tank 4 through a pipeline. The biogas outlet of the three-phase separator 3 is connected to the inlet of the gas storage tank 4.

[0034] The dosing mechanism includes a sodium hydroxide dosing machine 5, a magnesium chloride dosing machine 6, and a PAM dosing machine 7. The reagent outlet of the sodium hydroxide dosing machine 5 is connected to the reagent inlet of the anaerobic fermentation mechanism and the phosphorus recovery mechanism. The reagent outlets of the magnesium chloride dosing machine 6 and the PAM dosing machine 7 are both connected to the reagent inlet of the agitator 29 of the phosphorus recovery mechanism.

[0035] The phosphorus recovery mechanism includes a sedimentation tank 11 connected to a biogas digester, and a stirrer 8 and a stirrer 9 are installed on one side of the sedimentation tank 11. An inclined tube 10 and a pH monitor 19 and an ORP monitor 20 for monitoring the pH value inside the sedimentation tank 11 are located above the sedimentation tank 11.

[0036] The sludge treatment facility includes a sludge tank 12 that connects the biogas digester and the sedimentation tank 11. The sludge tank 12 is connected in sequence to the screw pump 13 and the screw press 14. A pH monitor 19 is installed in the sedimentation area where the agitator 18 is located. The inlet of the screw pump 13 is connected to the outlet of the sludge tank 12, and the outlet of the screw pump 13 is connected to the inlet of the screw press 14.

[0037] The PLC control equipment is connected to the equipment in the anaerobic fermentation unit, phosphorus recovery unit, sludge treatment unit, biogas recovery unit, and chemical dosing unit via electrical signals.

[0038] Referring to the attached diagrams in the instruction manual Figure 1 As shown, the anaerobic fermentation mechanism is installed according to the location of the biogas digester. A mixer 1, an inclined tube 2 and a three-phase separator 3 are installed on the biogas digester. A biogas monitor 15, a pH monitor 16, an ORP monitor 17 and a temperature monitor 18 are installed in the corresponding positions inside the biogas digester.

[0039] A gas storage tank 4 with a biogas recovery mechanism is installed on one side of the biogas digester. The biogas outlet of the three-phase separator 3 is connected to the inlet of the gas storage tank 4 through a pipeline to ensure that the biogas transmission path is unobstructed.

[0040] Settling tank 11 with phosphorus recovery mechanism connected to biogas digester; agitator 8 and agitator 9 are installed on one side of settling tank 11, and inclined tube 10 is installed above it. pH monitor 19 and ORP monitor 20 are installed in corresponding positions in settling tank 11, where pH monitor 19 corresponds to the settling area where agitator 8 is located.

[0041] Install the sludge treatment mechanism: Connect the sludge tank 12 to the residual sludge outlet of the biogas digester and sedimentation tank 11, and then connect the screw pump 13 and the screw press 14 in sequence to ensure that the outlet of the sludge tank 12 is connected to the inlet of the screw pump 13 and the outlet of the screw pump 13 is connected to the inlet of the screw press 14.

[0042] The sodium hydroxide dosing machine 5, magnesium chloride dosing machine 6, and PAM dosing machine 7 are equipped with dosing mechanisms. The dosing outlet of the sodium hydroxide dosing machine 5 is connected to the dosing inlet of the anaerobic fermentation unit and the phosphorus recovery unit. The dosing outlets of the magnesium chloride dosing machine 6 and the PAM dosing machine 7 are connected to the dosing inlet of the agitator 29 of the phosphorus recovery unit.

[0043] Connect the cables of the PLC control equipment to all the equipment in the anaerobic fermentation unit, phosphorus recovery unit, sludge treatment unit, biogas recovery unit and dosing unit respectively, and complete the circuit and control system debugging;

[0044] Follow these steps when using it:

[0045] Step 1: Put the dewatered phosphorus-containing sludge with a solids content of 5-8% into the biogas digester of the anaerobic fermentation unit, and add water as needed;

[0046] The PLC-controlled equipment starts the mixer 1 and runs it at a speed of 5-15 r / min for 8-16 hours a day. At the same time, the heating device is controlled by the temperature monitor 18 to maintain the temperature of the biogas digester at 30℃ or above. The pH value of the material is controlled at 6.5-7.5 by the pH value monitor 16 for 8-15 days.

[0047] Step 2: The biogas produced by anaerobic fermentation is separated by a three-phase separator 3, monitored by a biogas monitor 15, and then transported to a gas storage tank 4 through a pipeline for storage.

[0048] Step 3: The phosphorus-rich supernatant produced by anaerobic fermentation is guided to sedimentation tank 11 through inclined tube 2; the PLC control equipment adjusts the pH value in sedimentation tank 11 to 8.5-9.0 according to the data of pH monitor 19 through sodium hydroxide dosing machine 5;

[0049] Subsequently, magnesium chloride is added to stirrer 29 via magnesium chloride dosing machine 6 to generate struvite. PAM is added to stirrer 29 via PAM dosing machine 7 to accelerate precipitation. ORP monitor 20 monitors the reaction environment in real time. The precipitated struvite is collected via inclined tube 210, dried, and then used.

[0050] Step 4: The remaining sludge produced by the biogas digester and sedimentation tank 11 is discharged to the sludge tank 12. The PLC control equipment monitors the liquid level of the sludge tank 12 and starts the screw pump 13 to transport the sludge to the screw press 14 for dewatering. After dewatering, the sludge is transported off-site for treatment.

[0051] Throughout all steps, the PLC control equipment monitors the operating status of each mechanism in real time through electrical signals, automatically adjusts parameters, achieves fully automated collaborative processing, and further realizes full-process control.

[0052] Working principle: When using this sludge anaerobic fermentation biogas production and phosphorus recovery integrated device, dewatered phosphorus-containing sludge is put into the biogas digester of the anaerobic fermentation unit. The PLC control equipment starts the mixer 1 to run and stir the sludge inside. At the same time, the temperature of the biogas digester is monitored by the temperature monitor 18 and the heating device configured in the biogas digester is controlled to maintain the temperature at 30℃ or above. The pH value monitor 16 monitors the pH value.

[0053] As the sludge decomposes organic matter through hydrolytic acidifying bacteria and methanogenic bacteria, the biogas produced is separated by a three-phase separator 3, monitored by a biogas monitor 15, and then transported through a pipeline to the gas storage tank 4 of the biogas recovery mechanism for storage. The PO43- and NH44 released during the reaction process remain in the phosphorus-rich supernatant and are guided by inclined tube 2.

[0054] The phosphorus-rich supernatant flows into the sedimentation tank 11, which is connected to the biogas digester and the phosphorus recovery unit. Based on the pH value data from the pH monitor 19 in the sedimentation area where the agitator 8 is located, the PLC control equipment controls the sodium hydroxide dosing machine 5 of the dosing unit to add chemicals to the phosphorus recovery unit to adjust the pH value. Simultaneously, the magnesium chloride dosing machine 6 adds magnesium chloride to the agitator 9 to provide magnesium. 2+ With PO4 3 -、NH4 + The reaction produces struvite. Then, the PAM agent dosing machine 7 adds PAM agent to the stirrer 9 to accelerate the sedimentation of struvite. The ORP monitor 20 monitors the reaction environment in real time. The precipitated struvite is collected through the inclined tube 210 and can be used after drying.

[0055] The small amount of residual sludge generated in the biogas digester of the anaerobic fermentation unit and the sedimentation tank 11 of the phosphorus recovery unit is discharged to the sludge tank 12 of the sludge treatment unit. The PLC control equipment monitors the liquid level of the sludge tank 12 and starts the screw pump 13 to transport the sludge to the screw press 14 for dewatering treatment. The dewatered sludge is then transported off-site for disposal.

[0056] The entire process is controlled by PLC and connected to the electrical signals of the equipment in each mechanism, achieving fully automated operation and completing the synergistic treatment of sludge anaerobic fermentation to produce biogas and phosphorus recovery, thus increasing the overall practicality.

[0057] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus, characterized in that, include: Anaerobic fermentation unit, phosphorus recovery unit, sludge treatment unit, biogas recovery unit, dosing unit and PLC control equipment, wherein the anaerobic fermentation unit includes a mixer (1), inclined tube one (2) and three-phase separator (3) installed on the biogas digester, as well as a biogas monitor (15), pH value monitor one (16), ORP monitor one (17) and temperature monitor (18) for monitoring the biogas digester; The biogas recovery mechanism includes a gas storage tank (4), and the gas storage tank (4) collects biogas from the biogas digester; The dosing mechanism includes a sodium hydroxide dosing machine (5), a magnesium chloride dosing machine (6), and a PAM agent dosing machine (7); The phosphorus recovery mechanism includes a sedimentation tank (11) connected to the biogas digester, and a stirrer 1 (8) and a stirrer 2 (9) are installed on one side of the sedimentation tank (11), and an inclined tube 2 (10) and a pH monitor 2 (19) and an ORP monitor 2 (20) are installed above the sedimentation tank (11). The sludge treatment mechanism includes a sludge tank (12) connecting the biogas digester and the sedimentation tank (11), and the sludge tank (12) is connected in sequence to the screw pump (13) and the screw press (14); The PLC control equipment is connected to the equipment in the anaerobic fermentation unit, phosphorus recovery unit, sludge treatment unit, biogas recovery unit, and chemical dosing unit via electrical signals.

2. The integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus according to claim 1, characterized in that: The phosphorus-rich supernatant outlet of the anaerobic fermentation unit is connected to the inlet of the sedimentation tank (11), and the residual sludge outlets of the anaerobic fermentation unit and the phosphorus recovery unit are both connected to the inlet of the sludge tank (12).

3. The integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus according to claim 1, characterized in that: The gas storage tank (4) is installed on one side of the biogas digester, and biogas is transported to the gas storage tank (4) through a pipeline. The biogas outlet of the three-phase separator (3) is connected to the inlet of the gas storage tank (4).

4. The integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus according to claim 1, characterized in that: The reagent outlet of the sodium hydroxide dosing machine (5) is connected to the reagent inlet of the anaerobic fermentation unit and the phosphorus recovery unit.

5. The integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus according to claim 1, characterized in that: The reagent outlets of the magnesium chloride dosing machine (6) and the PAM reagent dosing machine (7) are both connected to the reagent inlet of the agitator (9) of the phosphorus recovery mechanism.

6. The integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus according to claim 1, characterized in that: A pH monitor (19) is installed in the sedimentation area where the agitator (8) is located.

7. The integrated device for anaerobic fermentation of sludge to produce biogas and recover phosphorus according to claim 1, characterized in that: The inlet of the screw pump (13) is connected to the outlet of the sludge tank (12), and the outlet of the screw pump (13) is connected to the inlet of the screw press (14).

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