Biological protease combined with secondary anaerobic digestion method for sludge dewatering

Abstract

This invention discloses a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion, relating to the field of sludge dewatering technology. Specifically, it includes the following steps: collecting sludge from a wastewater treatment system and pretreating the sludge; adding the pretreated sludge to a stirred tank for heat treatment and uniform stirring; intermittently adding biological protease to the stirred tank and continuously stirring for 1-2 hours at a stirring speed controlled at 260-400 r / min; sealing the stirred tank and controlling the temperature and humidity inside by heating and water spraying; and subjecting the treated sludge to primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat. This invention promotes the degradation and decomposition of organic matter in sludge, increases the solubility and release rate of organic matter, ensures uniform distribution of biological protease and other components in the sludge, enhances the effectiveness of biological protease, and accelerates the degradation of organic matter.

Description

Technical Field

[0001] This invention relates to the field of sludge dewatering technology, and in particular to a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion. Background Technology

[0002] Biological proteases are naturally occurring biological proteins with the efficient ability to decompose organic matter, accelerating the degradation of organic matter in sludge. Secondary anaerobic digestion, a microbial degradation process conducted under anaerobic conditions, effectively degrades organic matter and reduces sludge volume. The principle of sludge dewatering using biological proteases combined with secondary anaerobic digestion is to promote the degradation of organic matter in the sludge through the addition of biological proteases, while simultaneously utilizing secondary anaerobic digestion for sludge degradation and concentration, ultimately achieving sludge dewatering. This method not only improves sludge treatment efficiency but also reduces energy consumption and the use of chemical agents, resulting in significant environmental and economic benefits. Therefore, sludge dewatering using biological proteases combined with secondary anaerobic digestion has broad application prospects in the field of sludge treatment.

[0003] A search revealed Chinese patent application CN2023117581985, which discloses a method and apparatus for sludge dewatering using a combination of biological protease and secondary anaerobic digestion. The method includes: hydrolyzing sludge with hot water at 0-140°C; subjecting the hydrolyzed sludge to primary anaerobic digestion at 50-55°C; mixing the primary anaerobic digested sludge with biological protease at a dosage of 0.5-1‰ of the sludge dry weight; subjecting the mixed sludge to secondary anaerobic digestion at 37-43°C; adding a flocculant and mixing to settle the sludge; and pressing the settled sludge multiple times under pressure. The aforementioned method and apparatus for sludge dewatering using a combination of biological protease and secondary anaerobic digestion has the following shortcomings:

[0004] The above method reduces the temperature of the hot hydrolysis treatment, thus reducing the temperature drop loss in the subsequent anaerobic digestion. By enhancing the decomposition of extracellular polymers and organic matter through biological proteases, the level of resource utilization is improved, and the gas production rate is increased compared to conventional anaerobic digestion. However, the viscosity and moisture content of the sludge are relatively high, which increases the burden on the subsequent dewatering equipment, increases costs, and requires more time and energy, thereby reducing the dewatering efficiency of the sludge. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by protease combined with secondary anaerobic digestion for sludge dewatering.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion includes the following steps:

[0008] S1: Collect sludge from the wastewater treatment system and pre-treat the sludge;

[0009] S2: The pretreated sludge is put into a mixing tank for heat treatment and uniform mixing;

[0010] S3: Intermittently add biological protease to the stirred tank and stir continuously for 1-2 hours, with the stirring speed controlled at 260-400 r / min;

[0011] S4: Seal the mixing vessel and control the temperature and humidity inside the vessel by heating and spraying water;

[0012] S5: The treated sludge undergoes primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat.

[0013] S6: The sludge after being treated with biological protease combined with secondary anaerobic digestion is dewatered to obtain dry sludge solids.

[0014] Preferably, in step S4, the temperature inside the stirring vessel is maintained at 45-60℃, the humidity is maintained at 50-70%, and the settling time is 3-5 hours.

[0015] Further: In step S2, the stirring speed is controlled at 350-820 r / min, and the heating temperature is controlled at 50-70℃.

[0016] Based on the aforementioned scheme: In step S1, the sludge is pretreated, and the specific method is as follows:

[0017] S11: Collect 500g of sludge from the wastewater treatment system and soak the sludge in 220ml of sulfonate-type ionic liquid;

[0018] S12: Mix and stir the sludge and sulfonate-type ionic liquid to react, and maintain the heating temperature at 20-35℃;

[0019] S13: After standing for 1-2 hours, the sludge mixed with sulfonate ionic liquid is introduced into a centrifuge for solid-liquid separation after filtration.

[0020] S14: Dry the sludge from which sulfonate-type ionic liquid has been removed, evaporate the excess sulfonate-type ionic liquid, and dissolve the solid sludge in 300ml of water for later use.

[0021] A preferred embodiment of the aforementioned scheme is that, in step S12, the mixing and stirring reaction speed is 150 r / min, and the mixing and stirring reaction time is 30-50 min.

[0022] As a further aspect of the present invention: the primary anaerobic digestion process in step S5 comprises the following specific steps:

[0023] Primary anaerobic digestion:

[0024] A1: Methanogens and anaerobic ammonia oxidizing bacteria were selected as microbial strains and introduced into a primary anaerobic digester to establish a co-culture system;

[0025] A2: Regulating the environmental conditions within the co-culture system;

[0026] A3: Regulate the ratio and density of methanogens and anaerobic ammonia oxidizers to promote their interaction and synergistic effect;

[0027] A4: The sludge treated with biological protease is fed into a primary anaerobic digester for primary sludge organic matter degradation.

[0028] Meanwhile, in step A2, the temperature in the co-culture system is controlled at 35-40℃, the pH value at 6.5-7.5, and the system is anaerobic, with 1-5% carbon source, 0.4-1% nitrogen source, and 0.1-0.3% phosphorus source.

[0029] As a preferred embodiment of the present invention: in step A3, the ratio of methanogens to anaerobic ammonia oxidizers is controlled to be between 2:1, and the density is controlled to be between 10^6 and 10^8 cells / mL.

[0030] Meanwhile, the secondary anaerobic digestion process in step S5 consists of the following steps:

[0031] Secondary anaerobic digestion:

[0032] B1: Construct a two-stage anaerobic digester and select porous ceramics as the carrier material for immobilized microorganisms;

[0033] B2: Methanogens and sulfur-reducing bacteria were selected as microbial strains and inoculated onto porous ceramics to allow the microorganisms to adhere to the surface and form a fixed microbial film. Vitamin B and glutamic acid in a ratio of 3:2 were then introduced into the secondary anaerobic digester.

[0034] B3: Regulate the internal environmental conditions of the system, controlling the temperature to 30-50℃, pH to 6-7.6, oxygen-free environment, carbon source 1-4%, nitrogen source 0.4-1.2%, and phosphorus source 0.2-0.4%;

[0035] B4: The sludge after primary anaerobic digestion is introduced into the secondary anaerobic digester, allowing the sludge to fully contact the porous ceramic surface and complete the secondary sludge organic matter degradation treatment.

[0036] As a preferred embodiment of the present invention: In step S6, the sludge after undergoing biological protease combined with secondary anaerobic digestion is dewatered, and the specific steps are as follows:

[0037] S61: The sludge is fed into the dewatering zone of the magnetic field-assisted centrifugal dewatering machine;

[0038] S62: Apply an electric field to the dewatering zone to act on the sludge, control the movement of microorganisms and particulate matter, and promote the separation and discharge of water. The applied electric field is controlled at 2-15 kV / m.

[0039] S63: During the dehydration process, the moisture content and dehydration efficiency are monitored by a moisture meter, and the electric field parameters are adjusted according to the actual situation.

[0040] S64: The liquid wastewater generated during the dehydration process is treated by sedimentation and filtration before being discharged.

[0041] The beneficial effects of this invention are as follows:

[0042] 1. This method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion involves pre-treated sludge being heat-treated and uniformly stirred in a stirred tank. Biological protease is intermittently added to the stirred tank while it is sealed. Temperature and humidity inside the tank are controlled by heating and water spraying. This promotes the degradation and decomposition of organic matter in the sludge, increasing its solubility and release rate. It also ensures uniform distribution of the biological protease and other components in the sludge, enhancing the effectiveness of the protease and accelerating organic matter degradation. Furthermore, it facilitates full contact between the biological protease and the organic matter in the sludge, improving degradation efficiency. Under specific temperature and humidity conditions, microorganisms in the sludge further ferment and degrade the organic matter, promoting its degradation and release. Maintaining suitable temperature and humidity is conducive to microbial growth and activity, further improving digestion efficiency.

[0043] 2. This method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion involves soaking the sludge in an ionic liquid. The dissolving power of the ionic liquid effectively removes organic matter from the sludge, improving treatment efficiency. Furthermore, mixing and stirring the sludge and ionic liquid while maintaining a suitable temperature promotes the degradation of organic matter and accelerates the sludge treatment process. Simultaneously, filtration and solid-liquid separation effectively separate the ionic liquid from the dissolved organic matter, reducing energy consumption in subsequent treatment processes.

[0044] 3. This method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion involves the following steps: In the primary anaerobic digestion process, methanogens and anaerobic ammonia oxidizing bacteria are selected as microbial strains and a co-culture system is established. This promotes the degradation of organic matter, improves gas production efficiency, and regulates the environmental conditions within the system, including temperature, pH, carbon source, nitrogen source, and phosphorus source, to provide suitable conditions for microbial growth and metabolism. Simultaneously, controlling the ratio and density of methanogens and anaerobic ammonia oxidizing bacteria promotes their interaction and synergistic effect, enhancing the organic matter degradation effect. In the secondary anaerobic digestion process, methanogens and sulfur-reducing bacteria are selected as microbial strains and immobilized on porous ceramics. The introduction of vitamin B and glutamic acid promotes microbial activity and organic matter degradation efficiency, increases the degradation area of ​​microorganisms, improves the quality of organic matter degradation, and ensures that the sludge fully promotes gas generation and heat release during treatment. Attached Figure Description

[0045] Figure 1 This is the main flow chart of a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion proposed in this invention;

[0046] Figure 2 This is a flowchart illustrating the sludge pretreatment process in a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion proposed in this invention.

[0047] Figure 3 This is a flowchart of the primary anaerobic digestion process in a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion proposed in this invention.

[0048] Figure 4 This is a flowchart of a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion proposed in this invention;

[0049] Figure 5 This is a flowchart of a sludge dewatering method using a combination of biological protease and secondary anaerobic digestion proposed in this invention. Detailed Implementation

[0050] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0051] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0052] A method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion. Figure 1 As shown, it includes the following steps:

[0053] S1: Collect sludge from the wastewater treatment system and pre-treat the sludge;

[0054] S2: The pretreated sludge is put into a mixing tank for heat treatment and uniform mixing. The mixing speed is controlled at 350-820 r / min and the heating temperature is controlled at 50-70℃.

[0055] S3: Intermittently add biological protease to the stirred tank and stir continuously for 1-2 hours, with the stirring speed controlled at 260-400 r / min;

[0056] S4: Seal the mixing vessel, and control the temperature and humidity inside the vessel by heating and spraying water. Maintain the temperature inside the vessel at 45-60℃ and the humidity at 50-70%, and let it stand for 3-5 hours.

[0057] S5: The treated sludge undergoes primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat.

[0058] S6: The sludge after being treated with biological protease combined with secondary anaerobic digestion is dewatered to obtain dry sludge solids.

[0059] Through steps S2-S4, the degradation and decomposition of organic matter in sludge can be promoted, increasing the solubility and release rate of organic matter; the biological proteases and other components in the sludge can be evenly distributed, improving the effectiveness of the biological proteases and accelerating the degradation of organic matter; at the same time, it helps the biological proteases to fully contact the organic matter in the sludge, improving the degradation efficiency; under certain temperature and humidity conditions, the microorganisms in the sludge can be used for further fermentation and degradation, promoting the degradation and release of organic matter, and maintaining suitable temperature and humidity is conducive to the growth and activity of microorganisms, improving digestion efficiency.

[0060] Among them, such as Figure 2 As shown, in step S1, the sludge is pretreated, and the specific method is as follows:

[0061] S11: Collect 500g of sludge from the wastewater treatment system and soak the sludge in 220ml of sulfonate-type ionic liquid;

[0062] S12: Mix and stir the sludge and sulfonate-type ionic liquid at a speed of 150 r / min for 30-50 min, and maintain the heating temperature at 20-35℃;

[0063] S13: After standing for 1-2 hours, the sludge mixed with sulfonate ionic liquid is introduced into a centrifuge for solid-liquid separation after filtration.

[0064] S14: Dry the sludge from which sulfonate-type ionic liquid has been removed, evaporate the excess sulfonate-type ionic liquid, and dissolve the solid sludge in 300ml of water for later use.

[0065] Soaking sludge in ionic liquids utilizes the dissolving power of ionic liquids to effectively remove organic matter from the sludge, improving treatment efficiency. Furthermore, mixing and stirring the sludge and ionic liquids while maintaining a suitable temperature helps promote the degradation of organic matter and accelerates the sludge treatment process. Simultaneously, filtration and solid-liquid separation can effectively separate the ionic liquids from the dissolved organic matter, reducing energy consumption in subsequent treatment processes.

[0066] like Figure 3 and Figure 4 As shown, the specific steps in step S5 are as follows:

[0067] A: Primary anaerobic digestion treatment:

[0068] A1: Methanogens and anaerobic ammonia oxidizing bacteria were selected as microbial strains and introduced into a primary anaerobic digester to establish a co-culture system;

[0069] A2: Regulate the environmental conditions within the co-culture system, controlling the temperature to 35-40℃, pH to 6.5-7.5, anaerobic conditions, carbon source 1-5%, nitrogen source 0.4-1%, and phosphorus source 0.1-0.3%;

[0070] A3: Adjust the ratio and density of methanogens and anaerobic ammonia oxidizers, control the ratio of methanogens to anaerobic ammonia oxidizers to be between 2:1, and control the density to be between 10^6 and 10^8 cells / mL, so as to promote the interaction and synergistic effect between the two.

[0071] A4: The sludge treated with biological protease is fed into a primary anaerobic digester for primary sludge organic matter degradation.

[0072] B: Secondary anaerobic digestion treatment:

[0073] B1: Construct a two-stage anaerobic digester and select porous ceramics as the carrier material for immobilized microorganisms;

[0074] B2: Methanogens and sulfur-reducing bacteria were selected as microbial strains and inoculated onto porous ceramics to allow the microorganisms to adhere to the surface and form a fixed microbial film. Vitamin B and glutamic acid in a ratio of 3:2 were then introduced into the secondary anaerobic digester.

[0075] B3: Regulate the internal environmental conditions of the system, controlling the temperature to 30-50℃, pH to 6-7.6, oxygen-free environment, carbon source 1-4%, nitrogen source 0.4-1.2%, and phosphorus source 0.2-0.4%;

[0076] B4: The sludge after primary anaerobic digestion is introduced into the secondary anaerobic digester, allowing the sludge to fully contact the porous ceramic surface and complete the secondary sludge organic matter degradation treatment.

[0077] In the primary anaerobic digestion process, methanogens and anaerobic ammonia oxidizing bacteria are selected as microbial strains to establish a co-culture system. This promotes the degradation of organic matter, improves gas production efficiency, and regulates the environmental conditions within the system, including temperature, pH, carbon source, nitrogen source, and phosphorus source, to provide suitable conditions for microbial growth and metabolism. Simultaneously, controlling the ratio and density of methanogens and anaerobic ammonia oxidizing bacteria promotes their interaction and synergistic effect, enhancing the organic matter degradation effect. In the secondary anaerobic digestion process, methanogens and sulfur-reducing bacteria are selected as microbial strains and immobilized on porous ceramics. The introduction of vitamin B and glutamic acid promotes microbial activity and organic matter degradation efficiency, increases the degradation area of ​​microorganisms, improves the quality of organic matter degradation, and ensures that the sludge fully promotes gas generation and heat release during treatment.

[0078] In step S6, the sludge after undergoing combined biological protease and secondary anaerobic digestion is dewatered. The specific steps are as follows:

[0079] S61: The sludge is fed into the dewatering zone of the magnetic field-assisted centrifugal dewatering machine;

[0080] S62: Apply an electric field to the dewatering zone to act on the sludge, control the movement of microorganisms and particulate matter, and promote the separation and discharge of water. The applied electric field is controlled at 2-15 kV / m.

[0081] S63: During the dehydration process, the moisture content and dehydration efficiency are monitored by a moisture meter, and the electric field parameters are adjusted according to the actual situation.

[0082] S64: The liquid wastewater generated during the dehydration process is treated by sedimentation and filtration before being discharged.

[0083] Example 1:

[0084] A method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion, such as Figure 1 As shown, it includes the following steps:

[0085] S1: Collect sludge from the wastewater treatment system and pre-treat the sludge;

[0086] S2: The pretreated sludge is put into a mixing tank for heat treatment and uniform mixing. The mixing speed is controlled at 350 r / min and the heating temperature is controlled at 50℃.

[0087] S3: Intermittently add biological protease to the stirred tank and stir continuously for 1 hour, with the stirring speed controlled at 260 r / min;

[0088] S4: Seal the mixing vessel, control the temperature and humidity inside the vessel by heating and spraying water, keep the temperature inside the vessel at 45℃ and the humidity at 50%, and let it stand for 3 hours;

[0089] S5: The treated sludge undergoes primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat.

[0090] S6: The sludge after being treated with biological protease combined with secondary anaerobic digestion is dewatered to obtain dry sludge solids.

[0091] Among them, such as Figure 2 As shown, in step S1, the sludge is pretreated, and the specific method is as follows:

[0092] S11: Collect 500g of sludge from the wastewater treatment system and soak the sludge in 220ml of sulfonate-type ionic liquid;

[0093] S12: Mix and stir the sludge and sulfonate-type ionic liquid at a speed of 150 r / min for 30 min, and maintain the heating temperature at 20℃.

[0094] S13: After standing for 1 hour, the sludge mixed with sulfonate-type ionic liquid is introduced into a centrifuge for solid-liquid separation after filtration.

[0095] S14: Dry the sludge from which sulfonate-type ionic liquid has been removed, evaporate the excess sulfonate-type ionic liquid, and dissolve the solid sludge in 300ml of water for later use.

[0096] like Figure 3 and Figure 4 As shown, the specific steps in step S5 are as follows:

[0097] A: Primary anaerobic digestion treatment:

[0098] A1: Methanogens and anaerobic ammonia oxidizing bacteria were selected as microbial strains and introduced into a primary anaerobic digester to establish a co-culture system;

[0099] A2: Regulate the environmental conditions within the co-culture system, controlling the temperature to 35℃, pH to 6.5, anaerobic conditions, carbon source to 1%, nitrogen source to 0.4%, and phosphorus source to 0.1%.

[0100] A3: Adjust the ratio and density of methanogens and anaerobic ammonia oxidizers, control the ratio of methanogens to anaerobic ammonia oxidizers to be 2:1, and control the density to be 10^6 cells / mL, to promote the interaction and synergistic effect between the two.

[0101] A4: The sludge treated with biological protease is fed into a primary anaerobic digester for primary sludge organic matter degradation.

[0102] B: Secondary anaerobic digestion treatment:

[0103] B1: Construct a two-stage anaerobic digester and select porous ceramics as the carrier material for immobilized microorganisms;

[0104] B2: Methanogens and sulfur-reducing bacteria were selected as microbial strains and inoculated onto porous ceramics to allow the microorganisms to adhere to the surface and form a fixed microbial film. Vitamin B and glutamic acid in a ratio of 3:2 were then introduced into the secondary anaerobic digester.

[0105] B3: Regulate the internal environmental conditions of the system, controlling the temperature to 30℃, pH to 6, oxygen-free environment, carbon source to 1%, nitrogen source to 0.4%, and phosphorus source to 0.2%.

[0106] B4: The sludge after primary anaerobic digestion is introduced into the secondary anaerobic digester, allowing the sludge to fully contact the porous ceramic surface and complete the secondary sludge organic matter degradation treatment.

[0107] like Figure 5 As shown, in step S6, the sludge after undergoing biological protease combined with secondary anaerobic digestion is dewatered. The specific steps are as follows:

[0108] S61: The sludge is fed into the dewatering zone of the magnetic field-assisted centrifugal dewatering machine;

[0109] S62: Apply an electric field to the dewatering zone to act on the sludge, control the movement of microorganisms and particulate matter, and promote the separation and discharge of water. The applied electric field is controlled at 2kV / m.

[0110] S63: During the dehydration process, the moisture content and dehydration efficiency are monitored by a moisture meter, and the electric field parameters are adjusted according to the actual situation.

[0111] S64: The liquid wastewater generated during the dehydration process is treated by sedimentation and filtration before being discharged.

[0112] Example 2:

[0113] A method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion, such as Figure 1 As shown,

[0114] Includes the following steps:

[0115] S1: Collect sludge from the wastewater treatment system and pre-treat the sludge;

[0116] S2: The pretreated sludge is put into a mixing tank for heat treatment and uniform mixing. The mixing speed is controlled at 710 r / min and the heating temperature is controlled at 62℃.

[0117] S3: Intermittently add biological protease to the stirred tank and stir continuously for 1.3 hours at a stirring speed of 320 r / min;

[0118] S4: Seal the mixing vessel, control the temperature and humidity inside the vessel by heating and spraying water, maintain the temperature inside the vessel at 51℃ and the humidity at 60%, and let it stand for 4 hours;

[0119] S5: The treated sludge undergoes primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat.

[0120] S6: The sludge after being treated with biological protease combined with secondary anaerobic digestion is dewatered to obtain dry sludge solids.

[0121] Among them, such as Figure 2 As shown, in step S1, the sludge is pretreated, and the specific method is as follows:

[0122] S11: Collect 500g of sludge from the wastewater treatment system and soak the sludge in 220ml of sulfonate-type ionic liquid;

[0123] S12: Mix and stir the sludge and sulfonate-type ionic liquid at a speed of 150 r / min for 43 min, and maintain the heating temperature at 30℃.

[0124] S13: After standing for 1.4 hours, the sludge mixed with sulfonate-type ionic liquid is introduced into a centrifuge for solid-liquid separation after filtration.

[0125] S14: Dry the sludge from which sulfonate-type ionic liquid has been removed, evaporate the excess sulfonate-type ionic liquid, and dissolve the solid sludge in 300ml of water for later use.

[0126] like Figure 3 and Figure 4 As shown, the specific steps in step S5 are as follows:

[0127] A: Primary anaerobic digestion treatment:

[0128] A1: Methanogens and anaerobic ammonia oxidizing bacteria were selected as microbial strains and introduced into a primary anaerobic digester to establish a co-culture system;

[0129] A2: Adjust the environmental conditions within the co-culture system to control the temperature at 36℃, pH at 7, anaerobic conditions, carbon source at 2.5%, nitrogen source at 0.6%, and phosphorus source at 0.15%.

[0130] A3: Adjust the ratio and density of methanogens and anaerobic ammonia oxidizers, control the ratio of methanogens to anaerobic ammonia oxidizers to be 2:1, and control the density to be 10^6.8 cells / mL, so as to promote the interaction and synergistic effect between the two.

[0131] A4: The sludge treated with biological protease is fed into a primary anaerobic digester for primary sludge organic matter degradation.

[0132] B: Secondary anaerobic digestion treatment:

[0133] B1: Construct a two-stage anaerobic digester and select porous ceramics as the carrier material for immobilized microorganisms;

[0134] B2: Methanogens and sulfur-reducing bacteria were selected as microbial strains and inoculated onto porous ceramics to allow the microorganisms to adhere to the surface and form a fixed microbial film. Vitamin B and glutamic acid in a ratio of 3:2 were then introduced into the secondary anaerobic digester.

[0135] B3: Regulate the internal environmental conditions of the system, controlling the temperature to 42℃, pH to 7.2, oxygen-free environment, carbon source to 3%, nitrogen source to 1%, and phosphorus source to 0.32%;

[0136] B4: The sludge after primary anaerobic digestion is introduced into the secondary anaerobic digester, allowing the sludge to fully contact the porous ceramic surface and complete the secondary sludge organic matter degradation treatment.

[0137] In step S6, the sludge after undergoing combined biological protease and secondary anaerobic digestion is dewatered. The specific steps are as follows:

[0138] S61: The sludge is fed into the dewatering zone of the magnetic field-assisted centrifugal dewatering machine;

[0139] S62: Apply an electric field to the dewatering zone to act on the sludge, control the movement of microorganisms and particulate matter, and promote the separation and discharge of water. The applied electric field is controlled at 8kV / m.

[0140] S63: During the dehydration process, the moisture content and dehydration efficiency are monitored by a moisture meter, and the electric field parameters are adjusted according to the actual situation.

[0141] S64: The liquid wastewater generated during the dehydration process is treated by sedimentation and filtration before being discharged.

[0142] Example 3:

[0143] A method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion, such as Figure 1 As shown, it includes the following steps:

[0144] S1: Collect sludge from the wastewater treatment system and pre-treat the sludge;

[0145] S2: The pretreated sludge is put into a mixing tank for heat treatment and uniform mixing. The mixing speed is controlled at 820 r / min and the heating temperature is controlled at 70℃.

[0146] S3: Intermittently add biological protease to the stirred tank and stir continuously for 2 hours, with the stirring speed controlled at 400 r / min;

[0147] S4: Seal the mixing vessel, and control the temperature and humidity inside the vessel by heating and spraying water. Maintain the temperature inside the vessel at 60℃ and the humidity at 70%, and let it stand for 5 hours.

[0148] S5: The treated sludge undergoes primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat.

[0149] S6: The sludge after being treated with biological protease combined with secondary anaerobic digestion is dewatered to obtain dry sludge solids.

[0150] Among them, such as Figure 2 As shown, in step S1, the sludge is pretreated, and the specific method is as follows:

[0151] S11: Collect 500g of sludge from the wastewater treatment system and soak the sludge in 220ml of sulfonate-type ionic liquid;

[0152] S12: Mix and stir the sludge and sulfonate-type ionic liquid at a speed of 150 r / min for 50 min, and maintain the heating temperature at 35℃.

[0153] S13: After standing for 2 hours, the sludge mixed with sulfonate-type ionic liquid is introduced into a centrifuge for solid-liquid separation after filtration.

[0154] S14: Dry the sludge from which sulfonate-type ionic liquid has been removed, evaporate the excess sulfonate-type ionic liquid, and dissolve the solid sludge in 300ml of water for later use.

[0155] like Figure 3 and Figure 4As shown, the specific steps in step S5 are as follows:

[0156] A: Primary anaerobic digestion treatment:

[0157] A1: Methanogens and anaerobic ammonia oxidizing bacteria were selected as microbial strains and introduced into a primary anaerobic digester to establish a co-culture system;

[0158] A2: Regulate the environmental conditions within the co-culture system, controlling the temperature to 40℃, pH to 7.5, anaerobic conditions, carbon source to 5%, nitrogen source to 1%, and phosphorus source to 0.3%.

[0159] A3: Adjust the ratio and density of methanogens and anaerobic ammonia oxidizers, control the ratio of methanogens to anaerobic ammonia oxidizers to be 2:1, and control the density to be 10^8 cells / mL, so as to promote the interaction and synergistic effect between the two.

[0160] A4: The sludge treated with biological protease is fed into a primary anaerobic digester for primary sludge organic matter degradation.

[0161] B: Secondary anaerobic digestion treatment:

[0162] B1: Construct a two-stage anaerobic digester and select porous ceramics as the carrier material for immobilized microorganisms;

[0163] B2: Methanogens and sulfur-reducing bacteria were selected as microbial strains and inoculated onto porous ceramics to allow the microorganisms to adhere to the surface and form a fixed microbial film. Vitamin B and glutamic acid in a ratio of 3:2 were then introduced into the secondary anaerobic digester.

[0164] B3: Regulate the internal environmental conditions of the system, controlling the temperature to 50℃, pH to 7.6, oxygen-free environment, carbon source to 4%, nitrogen source to 1.2%, and phosphorus source to 0.4%.

[0165] B4: The sludge after primary anaerobic digestion is introduced into the secondary anaerobic digester, allowing the sludge to fully contact the porous ceramic surface and complete the secondary sludge organic matter degradation treatment.

[0166] like Figure 5 As shown, in step S6, the sludge after undergoing biological protease combined with secondary anaerobic digestion is dewatered. The specific steps are as follows:

[0167] S61: The sludge is fed into the dewatering zone of the magnetic field-assisted centrifugal dewatering machine;

[0168] S62: Apply an electric field to the dewatering zone to act on the sludge, control the movement of microorganisms and particulate matter, and promote the separation and discharge of water. The applied electric field is controlled at 15kV / m.

[0169] S63: During the dehydration process, the moisture content and dehydration efficiency are monitored by a moisture meter, and the electric field parameters are adjusted according to the actual situation.

[0170] S64: The liquid wastewater generated during the dehydration process is treated by sedimentation and filtration before being discharged.

[0171] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for sludge dewatering using a combination of biological protease and secondary anaerobic digestion, characterized in that, Includes the following steps: S1: Collect sludge from the wastewater treatment system and pre-treat the sludge; S2: The pretreated sludge is put into a mixing tank for heat treatment and uniform mixing; S3: Intermittently add biological protease to the stirred tank and stir continuously for 1-2 hours, with the stirring speed controlled at 260-400 r / min; S4: Seal the mixing vessel and control the temperature and humidity inside the vessel by heating and spraying water; S5: The treated sludge undergoes primary and secondary anaerobic digestion, where microorganisms decompose organic matter, releasing gases and generating heat. S6: The sludge after biological protease combined with secondary anaerobic digestion is dewatered to obtain dry sludge solids. The specific steps of the primary anaerobic digestion process in step S5 are as follows: Primary anaerobic digestion: A1: Methanogens and anaerobic ammonia oxidizing bacteria were selected as microbial strains and introduced into a primary anaerobic digester to establish a co-culture system; A2: Regulate the environmental conditions within the co-culture system, controlling the temperature at 35-40℃, the pH at 6.5-7.5, ensuring an anaerobic environment, and maintaining a carbon source of 1-5%, a nitrogen source of 0.4-1%, and a phosphorus source of 0.1-0.3%. A3: Adjust the ratio and density of methanogens and anaerobic ammonia oxidizers to promote their interaction and synergistic effect, control the ratio of methanogens to anaerobic ammonia oxidizers to be between 2:1, and control the density to be between 10^6 and 10^8 cells / mL. A4: The sludge treated with biological protease is fed into a primary anaerobic digester for primary sludge organic matter degradation.

2. The biological protease combined two-stage anaerobic digestion method for sludge dewatering according to claim 1, characterized in that, In step S4, the temperature inside the stirred tank is maintained at 45-60℃, the humidity is maintained at 50-70%, and the settling time is 3-5 hours.

3. The biological protease combined two-stage anaerobic digestion method for sludge dewatering according to claim 1, characterized in that, In step S2, the stirring speed is controlled at 350-820 r / min, and the heating temperature is controlled at 50-70℃.

4. The biological protease combined two-stage anaerobic digestion method for sludge dewatering according to claim 1, characterized in that, In step S1, the sludge is pretreated, and the specific method is as follows: S11: Collect 500g of sludge from the wastewater treatment system and soak the sludge in 220ml of sulfonate-type ionic liquid; S12: Mix and stir the sludge and sulfonate-type ionic liquid to react, and maintain the heating temperature at 20-35℃; S13: After standing for 1-2 hours, the sludge mixed with sulfonate ionic liquid is introduced into a centrifuge for solid-liquid separation after filtration. S14: Dry the sludge from which sulfonate-type ionic liquid has been removed, evaporate the excess sulfonate-type ionic liquid, and dissolve the solid sludge in 300ml of water for later use.

5. The biological protease combined two-stage anaerobic digestion method for sludge dewatering according to claim 4, characterized in that, In step S12, the mixing and stirring reaction rate is 150 r / min, and the mixing and stirring reaction time is 30-50 min.

6. The biological protease combined two-stage anaerobic digestion method for sludge dewatering according to claim 1, characterized in that, The secondary anaerobic digestion process in step S5 consists of the following steps: Secondary anaerobic digestion: B1: Construct a two-stage anaerobic digester and select porous ceramics as the carrier material for immobilized microorganisms; B2: Methanogens and sulfur-reducing bacteria were selected as microbial strains and inoculated onto porous ceramics to allow the microorganisms to adhere to the surface and form a fixed microbial film. Vitamin B and glutamic acid in a ratio of 3:2 were then introduced into the secondary anaerobic digester. B3: Regulate the internal environmental conditions of the system, controlling the temperature to 30-50℃, pH to 6-7.6, oxygen-free environment, carbon source 1-4%, nitrogen source 0.4-1.2%, and phosphorus source 0.2-0.4%; B4: The sludge after primary anaerobic digestion is introduced into the secondary anaerobic digester, allowing the sludge to fully contact the porous ceramic surface and complete the secondary sludge organic matter degradation treatment.

7. The biological protease combined two-stage anaerobic digestion method for sludge dewatering according to claim 1, characterized in that, In step S6, the sludge after undergoing combined biological protease and secondary anaerobic digestion is dewatered. The specific steps are as follows: S61: The sludge is fed into the dewatering zone of the magnetic field-assisted centrifugal dewatering machine; S62: Apply an electric field to the dewatering zone to act on the sludge, control the movement of microorganisms and particulate matter, and promote the separation and discharge of water. The applied electric field is controlled at 2-15 kV / m. S63: During the dehydration process, the moisture content and dehydration efficiency are monitored by a moisture meter, and the electric field parameters are adjusted according to the actual situation. S64: The liquid wastewater generated during the dehydration process is treated by sedimentation and filtration before being discharged.

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