Sludge conditioning device based on isoelectric point principle and synchronous resource recovery method

Abstract

The invention discloses a sludge conditioning device based on an isoelectric point principle and a synchronous resource recovery method, and the method mainly comprises the following working steps: S1, determination of a sludge isoelectric point: determining the pH value of a sludge system when the Zeta potential is equal to 0, namely the isoelectric point of the sludge system; s2, solid hydrochloric acid is dissolved into an acidic solution by adding water, and the pH value of the solution is controlled to be about 1.5; s3, inputting the sludge discharged from the secondary sedimentation tank into a solid-liquid separation device with a 500-mesh screen; and S4, inputting the supernate after solid-liquid separation into an ion exchange column with ion exchange resin. The method can reduce the loss of the sludge in the transmission process, increases the content of organic matters which can be utilized by microorganisms in the anaerobic digestion process, further increases the methane yield, and recovers metal ions in the supernatant while improving the methane production efficiency of sludge anaerobic digestion, so that further resource utilization is facilitated, and the method is suitable for industrial production. Meanwhile, the device has the advantages of small occupied area, simple structure, low energy consumption and safety in reagent use.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge conditioning, and particularly relates to a sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle. Background Art

[0002] With the popular application of the activated sludge process for domestic sewage treatment, the output of excess sludge has increased sharply, and the treatment and disposal forms of excess sludge have become increasingly severe. As a by-product of sewage treatment, sludge enriches the pollutants and nutrients in sewage (heavy metals, refractory organic compounds, persistent organic compounds, microplastics, and C, N, P, etc.). Therefore, sludge has the dual properties of "resource" and "pollution". EPS is regarded as the "skeleton" of sludge, maintaining the stability of sludge flocs. The carboxyl groups carried by EPS will combine with multivalent metal ions (Ca 2+ , Mg 2+ , Al 3+ , Fe 3+ etc.) through bridging and complexation to form organically bound metals, further strengthening the stability of sludge organic macromolecules and forming the semi-rigid structure of sludge. This makes it difficult to separate the metals in sludge and also affects the biodegradability of sludge.

[0003] Existing pretreatment methods (such as acid-base pretreatment, hydrothermal hydrolysis, and methods such as microwave, ultrasound, and high pressure) are mainly external measures to improve anaerobic digestion of sludge. By destroying sludge flocs, organic matter is dissolved out to facilitate microbial uptake and utilization. However, they do not fundamentally optimize the physical and chemical properties of sludge and do not solve the problem of heavy metal residues in sludge. Therefore, the digested biogas residues still have to face the problem of disposal of multi-valent metals. Therefore, it is still urgent to seek an economical, efficient, environmentally friendly, and low-carbon targeted sludge conditioning method. The isoelectric point pretreatment technology is a novel strategy that can retain the vast majority of organic matter in the sludge flocs while separating organically bound metals, so as to improve the biodegradability of sludge for microbial utilization in the subsequent anaerobic digestion process. During the anaerobic digestion process, it can increase the biogas production and the proportion of methane in the biogas, and shorten the reaction cycle of anaerobic digestion. Separate and recover the removed metal ions, which can be used to prepare flocculants for the sewage treatment stage and also facilitate the final disposal of biogas residues. The isoelectric point pretreatment process mainly includes: adjusting the pH value of the sludge to the isoelectric point; performing solid-liquid separation on the homogenized sludge after stirring; recovering the supernatant and recycling the metal ions in it; dissolving the solid-phase material in water to a specified solid content to update the solid-liquid interface; adjusting the sludge after the solid-liquid interface update to neutral for anaerobic digestion of the sludge. Thus, traditional isoelectric point pretreatment equipment needs to include: two sets of pH value adjustment devices; two sets of stirring devices; one set of solid-liquid separation devices. Traditional engineering technology equipment has all the following defects: overly complex composition; large floor area; high cost; high energy consumption; and large sludge loss due to the need to switch multiple sets of equipment during the treatment process. Therefore, it is necessary to develop a sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle with a small floor area, save the amount of chemicals consumed during the treatment process, reduce sludge loss, thereby further increasing the methane production during the anaerobic digestion process, and simultaneously recycling the metals in the sludge for resource utilization.

[0004] Patent CN219631593U discloses "a flat bag centrifuge", which is equipped with a lifting and hoisting component on the machine body to move the bag containing the solid phase substance after solid-liquid separation; Patent CN220364474U discloses "a self-cleaning high-pressure belt machine sludge pretreatment device", which, based on the belt filter press, cleans the filter press by adding a new high-pressure nozzle, thereby improving the use efficiency of the filter belt; Patent CN215250314U discloses "a sludge pretreatment device combining alkali and ultrasonic waves" which can perform ultrasonic crushing while adjusting the pH value of the sludge; Patent CN110054373A discloses "a horizontal screw press type offshore platform oily sludge pretreatment device", which can add medicine to the sludge and then perform solid-liquid separation to discharge the filter cake. However, the above processes have the following deficiencies: (1) The "flat bag centrifuge" can achieve solid-liquid separation and the recovery of supernatant, but it does not have a pH value adjustment system, and it cannot stir the sludge to homogeneity. In addition, the solid content rate of the filter cake is too high, which is likely to cause blockage of the filter cloth, inconvenient to clean, and has low use efficiency; (2) The "self-cleaning high-pressure belt machine sludge pretreatment device" can achieve solid-liquid separation and the cleaning of the filter belt, improving the solid-liquid separation efficiency, but it cannot achieve pH value adjustment and the recovery of supernatant; (3) The "sludge pretreatment device combining alkali and ultrasonic waves" has a pH value adjustment device and a sludge homogenization device, but it cannot achieve solid-liquid separation; (4) The "horizontal screw press type offshore platform oily sludge pretreatment device" only has a medicine adding device and a solid-liquid separation device and cannot perform sludge homogenization.

[0005] As described above, for this reason, we have designed a sludge conditioning device based on the isoelectric point principle and a synchronous resource recovery method to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to solve the deficiencies existing in the prior art, and a sludge conditioning device based on the isoelectric point principle and a synchronous resource recovery method are proposed.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A sludge conditioning device based on the isoelectric point principle and a synchronous resource recovery method mainly includes the following working steps:

[0009] Step S1, determination of the isoelectric point of the sludge: Determine the pH value of the sludge system when the Zeta potential is equal to 0, which is the isoelectric point of the sludge system;

[0010] Step S2, dissolve solid hydrochloric acid in water to form an acidic solution, and control the pH value of the solution at about 1.5;

[0011] Step S3: Input the sludge discharged from the secondary sedimentation tank into the inner barrel assembled by a 500-mesh sieve and a stainless-steel support. Ensure that the liquid discharge pipe and the sludge discharge pipe are in a closed state, and the sludge discharge gate is in an open state. Add an acidic solution through the liquid addition port to adjust the pH value. At the same time, start the motor to adjust the rotation speed of the outer barrel to make the acidic solution and the sludge system mix evenly. Control the pH value of the sludge system to the isoelectric point according to the adjustment system of the pH detector. At this time, stop adding the acidic solution;

[0012] Step S4: Stir the sludge system adjusted to the isoelectric point until it is homogeneous, so that the protons in the acidic solution fully combine and react with the sludge flocs;

[0013] Step S5: After the stirring is completed, close the sludge discharge gate, open the liquid discharge pipe, adjust the motor speed for solid-liquid separation, so that the organically bound metal is fully separated from the sludge flocs. After centrifugation, the liquid-phase substance is separated to the outer barrel under the action of centrifugal force and discharged through the liquid discharge pipe. Control the liquid discharge volume through the infrared sensor, collect the liquid-phase substance for subsequent resource utilization of metal elements. Under the action of the sieve, most of the solid-phase substances will be intercepted in the inner barrel;

[0014] Step S6: Close the liquid discharge pipe, open the sludge discharge gate, add tap water to the solid-phase substances until they are dissolved to the specified solid content state, start the motor to stir, and stir the sludge system with the updated solid-liquid interface until it is homogeneous;

[0015] Step S7: If the sludge needs to be anaerobically digested, adjust the pH value of the sludge system with the updated solid-liquid interface to neutral, discharge it through the sludge discharge pipe, and transport it to the sludge fermentation device for anaerobic digestion; if it is biogas residue, it can be directly discharged for disposal;

[0016] Step S8: The supernatant after solid-liquid separation enters the anion exchange column through a water pump for anion exchange to remove anionic impurities such as PO 4 3 -, SO 4 2- and CO 3 2- and then enter the cation exchange column to recover metal ions such as Al 3+ and Fe 3+ in the supernatant for resource utilization.

[0017] Preferably, in step S2, the acid used to adjust the pH is solid hydrochloric acid and bioacid;

[0018] In step S2, the isoelectric point of the secondary sedimentation tank sludge is generally between 2.0 and 4.0. Therefore, in order to reduce the addition of acidic solution so as not to affect the sludge solid content, the pH value of the acidic solution needs to be controlled at about 1.5.

[0019] Preferably, in the step S3, after testing, the particle size of the sludge system is generally 45-55 um, and the sludge system needs to be maintained in an acidic state and stirred for 4-5 h. Therefore, a 500-mesh stainless steel screen is selected, which can intercept most of the solid-phase substances in the screen, discharge the liquid-phase substances, and play a corrosion-resistant role in a strong acid environment.

[0020] Preferably, in the step S3, the pH value detector is installed in the outer barrel of the device and is used to measure the pH value of the entire sludge system during the process of adjusting the pH value.

[0021] Preferably, in the step S4, the stirring conditions are a rotation speed of 250-350 rad / min and stirring for 4-5 h.

[0022] Preferably, in the step S5, the centrifugation conditions are centrifugation at a centrifugal force of 10000g-12000g for 20-25 min;

[0023] In the step S5, during the discharging process, the infrared sensor will sense the light transmittance of the supernatant. When the light transmittance is lower than a specific value, the drain pipe will be closed to prevent the discharge of some small-particle-size sludge;

[0024] In the step S5, under the action of the reduction clutch, the centrifugation stops. At the same time, the suspension rod in the device will play a role in balancing and damping during the centrifugation process.

[0025] Preferably, in the step S6, the stirring conditions are: stirring at a rotation speed of 250-350 rad / min for 3-4 h;

[0026] In the step S6, the solid content rate of the initial sludge or biogas residue ranges from 1% to 3%, and the solid content rate of the subsequent operating sludge can be about 5%.

[0027] Preferably, in the step S7, the pH value range of the sludge system during discharging should be 6.8-7.0.

[0028] Preferably, in the step S8, the anion exchange column is filled with anion exchange resin, generally strong-base anion exchange resin, and the cation exchange column is filled with cation exchange resin, generally strong-acid cation exchange resin.

[0029] A sludge conditioning device based on the isoelectric point principle, including a sludge conditioning device, the sludge conditioning device includes a motor, a reduction clutch, a suspension rod, an outer barrel, an inner barrel, an air bag, a liquid adding port, a cover, a drain pipe, a sludge discharge pipe, a sludge discharge gate, an infrared sensor, a pH value detector, a circuit control panel, an anion exchange column and a cation exchange column;

[0030] The circuit control panel is installed in the stainless - steel housing of the device, which includes the main switch for controlling the device and switches for separately controlling each operating unit;

[0031] The motor and the reduction clutch are fixed on the base. The outer barrel and the inner barrel are vertically connected to the motor, and the inner and outer barrels can be controlled separately;

[0032] The outer barrel is made of stainless steel without holes, with a sludge discharge pipe and a liquid discharge pipe connected to the bottom, a pH detector installed on the side wall, and a cover on the upper part;

[0033] An infrared sensor and a water pump are installed at the outlet of the liquid discharge pipe connected to the outer barrel. A gas collection device and a liquid addition port are installed on the cover;

[0034] The inner barrel is composed of a 500 - mesh stainless - steel screen and a stainless - steel bracket. The two parts are fixed by welding, placed inside the outer barrel, and a sludge discharge gate is provided at the bottom of the side to lead to the inside of the outer barrel;

[0035] The anion - exchange column is filled with strongly basic ion - exchange resin, and the cation - exchange column is filled with strongly acidic ion - exchange resin.

[0036] Preferably, the added volume of sludge does not exceed 2 / 3 of the volume of the outer barrel. Before centrifugation, check the tightness of the cover, sludge discharge pipe, liquid discharge pipe, and sludge discharge gate. If the sludge volume is too large, it is easy to overflow during centrifugation, and a too - large sludge volume reduces the reaction efficiency of the sludge.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] 1. The present invention integrates the processes of pH value adjustment, solid - liquid separation, homogenization of the sludge system, and supernatant recovery treatment in the isoelectric point pretreatment process, further realizes the resource utilization of sludge and the engineering application of sludge pretreatment means, and strengthens the reduction, resource utilization, and harmlessness of sludge.

[0039] 2. The present invention can also reduce the loss of sludge during transportation, increase the content of organic matter that can be utilized by microorganisms in the anaerobic digestion process, and thus further increase the methane production.

[0040] 3. In the present invention, an acidic solution of solid - state hydrochloric acid or bio - acid is used to replace the traditional hydrochloric acid solution, reducing the use of hazardous chemicals and expanding the controllable range of the pH value of the acidic solution.

[0041] 4. While improving the methane production efficiency of sludge anaerobic digestion, the present invention recovers metal ions in the supernatant for further resource utilization.

[0042] 5. The present invention has the advantages of small floor area, simple structure, low energy consumption, and small amount of reagent used. Brief Description of the Drawings

[0043] Figure 1 Schematic structural diagram of a sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle proposed by the present invention;

[0044] Figure 2 Flow chart of a sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle proposed by the present invention.

[0045] In the figure: 1, pH value detector; 2, inner barrel; 3, reduction clutch; 4, 500-mesh sieve; 5, stainless steel bracket; 6, motor; 7, outer barrel; 8, air bag; 9, water pump; 10, infrared sensor; 11, switch; 12, sludge discharge pipe; 13, suspension rod; 14, liquid discharge pipe; 15, liquid addition port; 16, sludge discharge valve; 17, cover; 18, circuit control panel; 19, ion exchange column liquid discharge pipe; 20, anion exchange column; 21, cation exchange column; 22, ion exchange column liquid inlet pipe. Detailed implementation manners

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0047] Embodiment 1

[0048] Such as Figure 1 , a sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle. The system includes a motor, a reduction clutch, a suspension rod, an outer barrel, an inner barrel, an air bag, a liquid addition port, a cover, a liquid discharge pipe, a sludge discharge pipe, a sludge discharge gate, an infrared sensor, a pH value detector, a circuit control panel, an anion exchange column, and a cation exchange column;

[0049] The circuit control panel is installed on the stainless steel shell of the device, which includes the main switch of the control device and the switches for separately controlling each operation unit;

[0050] The motor 6 and the reduction clutch 3 are fixed on the base. The outer barrel 7 and the inner barrel 2 are vertically connected to the motor, and the inner and outer barrels can be controlled separately;

[0051] The outer barrel 7 is made of non-porous stainless steel, the bottom is connected to the sludge discharge pipe 12 and the liquid discharge pipe 14, the side wall is provided with a pH value detector 1, and the upper part is provided with a cover;

[0052] An infrared sensor 10 and a water pump 9 are provided at the outlet of the liquid discharge pipe 14 connected to the outer barrel 7. The cover is provided with a gas collection device 8 and a liquid addition port 15;

[0053] The inner barrel 2 is composed of a 500-mesh stainless steel screen 4 and a stainless steel bracket 5. The two parts are fixed by welding and placed inside the outer barrel 7. A sludge discharge sluice 16 is provided at the bottom of the side and leads to the inside of the outer barrel 7.

[0054] The anion exchange column 20 is filled with strongly basic ion exchange resin, and the cation exchange column 21 is filled with strongly acidic ion exchange resin.

[0055] The added volume of sludge shall not exceed 2 / 3 of the volume of the outer barrel. Before centrifugation, check the tightness of the cover, sludge discharge pipe, liquid discharge pipe, and sludge discharge sluice. If the sludge volume is too large, it is easy to overflow during centrifugation, and the reaction efficiency of the sludge will be reduced.

[0056] Using the above system, a sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle are as follows:

[0057] (1) Dissolve solid hydrochloric acid in water to form an acidic solution, and control the pH value of the solution at 1.5.

[0058] (2) Input the sludge discharged from the secondary sedimentation tank into the inner barrel, ensure that the liquid discharge pipe and sludge discharge pipe are closed, and the sludge discharge sluice is open. Add the acidic solution through the liquid addition port to adjust the pH value, and at the same time start the motor to adjust the rotation speed of the outer barrel to 250 rpm, so that the acidic solution and the sludge system are evenly mixed, adjust the pH value of the sludge system to the isoelectric point and stir until homogeneous.

[0059] (3) After stirring, close the sludge discharge sluice, open the liquid discharge pipe, adjust the centrifugal force of the motor to 12000 g for 20 min of solid-liquid separation. After centrifugation, the liquid-phase substance is separated to the outer barrel under the action of centrifugal force and discharged through the liquid discharge pipe. The liquid-phase substance passes through the anion exchange column and the cation exchange column in sequence to recover Fe 3+ and Al 3+ and other metals for resource utilization, and most of the solid-phase substances will be intercepted in the inner barrel.

[0060] (4) Close the liquid discharge pipe, open the sludge discharge sluice, add tap water to the solid-phase substance to dissolve it to a state with a solid content of about 5%, start the motor and stir at a rotation speed of 250 rpm for 3 h until homogeneous.

[0061] (5) Adjust the pH value of the sludge system after the solid-liquid interface is updated to 6.8, discharge it through the sludge discharge pipe, and transport it to the sludge fermentation device for anaerobic digestion. Under this treatment method, the metal recovery rate in the sludge can reach 65%.

[0062] Example 2

[0063] A sludge conditioning device and a synchronous resource recovery method based on the isoelectric point principle are as follows:

[0064] (1) Dissolve the biological acid in water to form an acidic solution, and control the pH value of the solution at 1.3;

[0065] (2) Input the digested biogas residue into the inner barrel, ensure that the drain pipe and sludge discharge pipe are in the closed state, and the sludge discharge sluice is in the open state. Add the acidic solution at the liquid inlet to adjust the pH value, and at the same time start the motor to adjust the rotation speed of the outer barrel to 300 rpm, so that the acidic solution and the biogas residue are evenly mixed, adjust the pH value of the system to the isoelectric point and stir until homogeneous;

[0066] (3) After the stirring is completed, close the sludge discharge sluice, open the drain pipe, adjust the centrifugal force of the motor to 10000 g for solid-liquid separation for 20 min. After centrifugation, the liquid-phase substance is separated to the outer barrel under the action of centrifugal force and enters the anion exchange column and cation exchange column successively through the drain pipe. The recovered metal elements are recycled, and most of the solid-phase substances will be intercepted in the inner barrel;

[0067] (4) Close the drain pipe, open the sludge discharge sluice, add tap water to the solid-phase substance and dissolve it to a state with a solid content of about 2%, and then discharge it for final disposal. Under this treatment method, the metal content recovered from the biogas residue can reach 60%.

[0068] Comparative Example 1

[0069] (1) Dissolve solid hydrochloric acid in water to form an acidic solution, and control the pH value of the solution at 1.3;

[0070] (2) Input the sludge discharged from the secondary sedimentation tank into the inner barrel, ensure that the drain pipe and sludge discharge pipe are in the closed state, and the sludge discharge sluice is in the open state. Add the acidic solution at the liquid inlet to adjust the pH value, and at the same time start the motor to adjust the rotation speed of the outer barrel to 300 rpm, so that the acidic solution and the sludge system are evenly mixed, adjust the pH value of the sludge system to the isoelectric point and stir until homogeneous;

[0071] (3) After the stirring is completed, close the sludge discharge sluice, open the drain pipe, adjust the centrifugal force of the motor to 7000 g for solid-liquid separation for 20 min. After centrifugation, the liquid-phase substance is separated to the outer barrel under the action of centrifugal force and discharged through the drain pipe. The liquid-phase substance passes through the anion exchange column and cation exchange column successively, and the recovered Fe 3+ and Al 3+ and other metals are used for resource utilization, and most of the solid-phase substances will be intercepted in the inner barrel;

[0072] (4) Close the drain pipe, open the sludge discharge sluice, add tap water to the solid-phase substance and dissolve it to a state with a solid content of about 5%, start the motor and stir at a rotation speed of 300 rpm for 3 h until homogeneous;

[0073] (5) Adjust the pH value of the sludge system after the solid-liquid interface is updated to 6.9, discharge it through the sludge discharge pipe, and transport it to the sludge fermentation device for anaerobic digestion. Under this treatment method, the metal recovery rate in the sludge can reach 43%.

[0074] As can be seen from Comparative Example 1, when low centrifugal force is used for solid-liquid separation, the obtained metal recovery rate is not good.

[0075] Comparative Example 2

[0076] (1) Dissolve the bioacid in water to form an acidic solution, and control the pH value of the solution at 1.5;

[0077] (2) Input the digested biogas residue into the inner barrel, ensure that the liquid discharge pipe and the sludge discharge pipe are in the closed state, and the sludge discharge sluice is in the open state. Add the acidic solution at the liquid addition port to adjust the pH value, and at the same time start the motor to adjust the rotation speed of the outer barrel to 250 rpm, so that the acidic solution and the biogas residue are evenly mixed, adjust the pH value of the sludge system to 3.5 (the isoelectric point is about 2.4), and stir until homogeneous;

[0078] (3) After the stirring is completed, close the sludge discharge sluice, open the liquid discharge pipe, adjust the motor centrifugal force to 10,000 g for solid-liquid separation for 20 min. After centrifugation, the liquid-phase substance is separated to the outer barrel under the action of centrifugal force and enters the anion exchange column and the cation exchange column successively through the liquid discharge pipe, and the recovered metal elements are recycled, and most of the solid-phase substances will be intercepted in the inner barrel;

[0079] (4) Close the liquid discharge pipe, open the sludge discharge sluice, add tap water to the solid-phase substance to dissolve it to a state with a solid content of about 2%, and then discharge it for final disposal. Under this treatment method, the metal content recovered from the biogas residue can reach 25%.

[0080] As can be seen from Comparative Example 2, when the pH value in the environment does not reach the isoelectric point, the obtained metal recovery rate is not good.

[0081] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0082] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0083] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A synchronous resource recovery method for a sludge conditioning device based on the isoelectric point principle, characterized in that: The main work steps include: Step S1, determination of the isoelectric point of sludge: determining the pH value of the sludge system when the Zeta potential is equal to 0, which is the isoelectric point of the sludge system; Step S2, adding water to solid hydrochloric acid to dissolve into an acidic solution, and controlling the pH value of the solution to about 1.5; Step S3, input the sludge discharged from the secondary sedimentation tank into the inner barrel assembled with a 500-mesh screen and a stainless steel bracket, ensure that the liquid discharge pipe and the sludge discharge pipe are in a closed state, and the sludge discharge gate is in an open state, add an acidic solution to the liquid addition port to adjust the pH value, and start the motor to adjust the speed of the outer barrel at the same time, so that the acidic solution and the sludge system are evenly mixed, and the pH value of the sludge system is controlled to the isoelectric point according to the adjustment system of the pH value detector, and then stop adding the acidic solution; Step S4, stirring the sludge system adjusted to the isoelectric point until it is homogeneous, so that the protons in the acidic solution fully combine with the sludge flocs and react; Step S5, after the stirring is completed, the sludge discharge gate is closed, the discharge pipe is opened, and the motor speed is adjusted to perform solid-liquid separation, so that the organically bound metals and the sludge flocs are fully separated. After centrifugation, the liquid phase material is separated into the outer barrel under the action of centrifugal force and discharged through the discharge pipe. The discharge volume is controlled by an infrared sensor, and the liquid phase material is collected for subsequent resource utilization of metal elements. Under the action of the screen, most of the solid phase material will be retained in the inner barrel; Step S6, close the liquid discharge pipe, open the sludge discharge gate, add tap water to the solid phase material to dissolve it to a specified solid content, start the motor to stir it, and stir the sludge system after the solid-liquid interface is updated to be homogeneous; Step S7: If the sludge needs to be anaerobic digested, the pH value of the sludge system after the solid-liquid interface is updated needs to be adjusted to neutral, and the sludge is discharged through the sludge discharge pipe and transported to the sludge fermentation device for anaerobic digestion; if it is biogas residue, it can be directly discharged for disposal; Step S8: The supernatant after solid-liquid separation enters the anion exchange column through a pump for anion exchange to remove PO4 in the supernatant. 3 -、SO4 2- and CO3 2- The anionic impurities such as ions are then sent to the cation exchange column to recover the Al in the supernatant. 3+ and Fe 3+ Metal ions such as iodine are easy to utilize as resources.

2. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In step S2, the acid used to adjust the pH is solid hydrochloric acid or biological acid; In step S2, the isoelectric point of the sludge in the secondary sedimentation tank is generally between 2.0 and 4.

0. Therefore, in order to reduce the addition of the acidic solution so as not to affect the solid content of the sludge, the pH value of the acidic solution needs to be controlled at about 1.

5.

3. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In step S3, after testing, the particle size of the sludge system is generally 45-55um, and the sludge system needs to be maintained in an acidic state and stirred for 4-5h. Therefore, a 500-mesh stainless steel screen is selected to retain most of the solid phase matter in the screen, discharge the liquid phase matter, and play a corrosion-resistant role in a strong acid environment.

4. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In step S3, a pH detector is installed in the outer barrel of the device to measure the pH value of the entire sludge system during the pH adjustment process.

5. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In the step S4, the stirring condition is a stirring speed of 250 to 350 rad / min for 4 to 5 hours.

6. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In step S5, the centrifugal condition is centrifugal force of 10000g to 12000g for 20 to 25 minutes; In step S5, during the discharge process, the infrared sensor senses the transmittance of the supernatant, and when the transmittance is lower than a specific value, the drain pipe is closed to prevent the discharge of some small-sized sludge; In step S5, the centrifuge stops under the action of the deceleration clutch, and the suspension rod in the device plays a role of balancing and shock absorption during the centrifugal process.

7. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In step S6, the stirring conditions are: stirring at a speed of 250 to 350 rad / min for 3 to 4 hours; In step S6, the solid content of the initial sludge or biogas residue is in the range of 1-3%, and the solid content of the subsequent sludge can be around 5%.

8. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1 is characterized in that: In step S7, the pH value of the sludge system during discharge should be in the range of 6.8 to 7.

0.

9. The synchronous resource recovery method of a sludge conditioning device based on the isoelectric point principle according to claim 1, characterized in that: In the step S8, the anion exchange column is filled with anion exchange resin, generally a strong base anion exchange resin, and the cation exchange column is filled with cation exchange resin, generally a strong acid cation exchange resin.

10. A sludge conditioning device based on the isoelectric point principle, characterized in that: The sludge conditioning device includes a motor, a reduction clutch, a suspension rod, an outer barrel, an inner barrel, an air bag, a liquid filling port, a sealing cover, a liquid discharge pipe, a sludge discharge pipe, a sludge discharge gate, an infrared sensor, a pH value detector, a circuit control panel, an anion exchange column and a cation exchange column; The circuit control panel is installed on the stainless steel housing of the device, which contains the main switch for controlling the device and the switch for individually controlling each operating unit; The motor and the deceleration clutch are fixed on the base, and the motor is vertically connected to the outer barrel and the inner barrel, so that the inner and outer barrels can be controlled separately; The outer barrel is made of non-porous stainless steel, with a mud discharge pipe and a liquid discharge pipe connected to the bottom, a pH value detector provided on the side wall, and a sealing cover provided on the top; An infrared sensor and a water pump are provided at the outlet of the liquid discharge pipe connected to the outer barrel, and a gas collection device and a liquid filling port are provided on the sealing cover; The inner barrel is composed of a 500-mesh stainless steel screen and a stainless steel bracket, which are fixed by welding and placed inside the outer barrel. A mud discharge gate is provided at the bottom of the side to the inside of the outer barrel. The anion exchange column is filled with a strong base ion exchange resin, and the cation exchange column is filled with a strong acid ion exchange resin.

11. A sludge conditioning device based on the isoelectric point principle according to claim 10, characterized in that: The volume of sludge added shall not exceed 2 / 3 of the volume of the outer barrel.

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