Rural sewage excess sludge pyrohydrolysis treatment equipment and sludge treatment method

Abstract

The invention relates to rural sewage excess sludge pyrohydrolysis treatment equipment and a sludge treatment method. The sludge thermal hydrolysis treatment equipment comprises a stirring tank; the sludge pump is connected with the stirring tank; the air energy heat pump is connected with the stirring tank and is used for providing heat into the stirring tank to raise the temperature in the tank to 70 DEG C; and the electric heating piece is arranged in the stirring tank and is used for maintaining the temperature in the tank at 80 DEG C. The sludge treatment method comprises the following steps: inputting rural sewage excess sludge into a stirring tank under a stirring condition; the air energy heat pump is started, and after the temperature in the tank is increased to 70 DEG C, the temperature is increased to 80 DEG C through the electric heating piece; adding a compound degradation promoting agent into the stirring tank under a stirring condition; and naturally precipitating until the sludge is separated from the supernate, and carrying out classified recovery treatment. Compared with the prior art, the method has the advantages that the excess sludge can be treated at a lower temperature, the treatment energy consumption of byproducts produced in the rural sewage biochemical reaction process is reduced, and the content of volatile suspended solids in the sludge is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge treatment, and in particular relates to a rural sewage surplus sludge thermal hydrolysis treatment device and a sludge treatment method. Background Art

[0002] The byproduct of wastewater biochemical treatment, excess sludge, is composed of complex microbial populations, extracellular polymers (EPS), organic matter adsorbed from wastewater, inorganic matter (such as heavy metals and gravel), and water, which can interact to form semi-rigid flocs. Microorganisms are usually embedded in the EPS matrix, which can form a network and interact with a large amount of organic and inorganic substances in the wastewater, thereby enhancing the semi-rigid structure of the flocs, which is the main constraint in the sludge reduction process.

[0003] At present, my country has developed a variety of treatment technologies around the destruction of sludge flocs and reduction of volume. Among them, thermal hydrolysis technology, as a common pretreatment method for sludge from urban sewage treatment plants, can decompose the difficult-to-degrade organic matter in the sludge into small molecules of easily degradable organic matter, and further reuse it as a carbon source. In addition, the thermal hydrolysis residue has good dehydration performance and is easy to achieve the reduction target. When thermal hydrolysis is used to treat sludge from urban sewage treatment plants, it is necessary to heat and pressurize it and operate it under high temperature (above 100°C). Although the by-product sludge of rural sewage treatment equipment is similar in nature to the sludge from urban sewage treatment plants, it is difficult to achieve heating and pressurization operating conditions due to the limitations of equipment site conditions.

[0004] Therefore, for the by-product sludge of rural sewage treatment equipment, a new type of treatment equipment and a supporting treatment method are still to be developed to realize the low-temperature hot water hydrolysis reaction of the sludge under normal pressure conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a rural sewage excess sludge thermal hydrolysis treatment device and a sludge treatment method in order to realize the low-temperature thermal hydrolysis reaction of rural sewage excess sludge under normal pressure conditions.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention first provides a rural sewage excess sludge thermal hydrolysis treatment device, which comprises:

[0008] Mixing tank;

[0009] A sludge pump connected to the mixing tank is used to transport sludge into the mixing tank;

[0010] The air energy heat pump connected to the mixing tank is used to provide heat to the mixing tank to raise the temperature inside the tank to 70°C;

[0011] The electric heating element arranged in the stirring tank is used to further provide heat to the stirring tank so as to maintain the temperature inside the tank at 80°C.

[0012] Furthermore, the stirring tank is provided with a sludge inlet, a supernatant discharge port and a sludge discharge port.

[0013] Furthermore, the output end of the sludge pump is connected to the sludge inlet.

[0014] Furthermore, the number of the supernatant discharge ports is 2-4 to accommodate the discharge of supernatant at different water levels.

[0015] Furthermore, the supernatant discharge port is connected to the carbon source addition port of the denitrification tank.

[0016] Furthermore, a heat exchange coil is provided in the stirring tank, and the air energy heat pump is connected to the heat exchange coil.

[0017] Furthermore, the stirring paddle in the stirring tank includes any one of a turbine stirring paddle, an anchor stirring paddle, a frame stirring paddle or a propeller stirring paddle, preferably a turbine stirring paddle.

[0018] Furthermore, the material of the stirring tank includes any one of carbon steel or stainless steel.

[0019] Furthermore, the electric heating element includes any one or more of an electric heating rod, an electric heating net, and an electric heating film, preferably an electric heating rod.

[0020] The present invention also provides a sludge treatment method using the above rural sewage excess sludge thermal hydrolysis treatment equipment, comprising the following steps:

[0021] S1: inputting the rural sewage surplus sludge into the mixing tank under stirring conditions;

[0022] S2: Turn on the air energy heat pump to raise the temperature in the tank to 70°C, then use the electric heating element to raise the temperature and maintain it at 80°C;

[0023] S3: Add EDTA and CaO into the stirring tank in sequence under stirring conditions;

[0024] S4: Natural sedimentation until the sludge and supernatant are separated and then classified and recycled.

[0025] Furthermore, in step S1, the initial stirring speed is 60-80 rpm, and the stirring speed is 120-140 rpm after the sludge rises to a predetermined height.

[0026] Furthermore, in step S3, the mass ratio of the amount of EDTA added to the rural sewage excess sludge is (0.02-0.03):1, and after adding EDTA, the stirring speed is increased to 160-180 rpm, and stirring is continued for 30-60 min.

[0027] Furthermore, in step S3, the mass ratio of the CaO feeding amount to the rural sewage excess sludge is (0.05-0.15):1, and stirring is continued for 30-60 minutes after adding CaO.

[0028] Furthermore, in step S4, the sedimentation time is 30-60 minutes, the separated supernatant is transported to the denitrification tank, and the separated sludge is discharged into the temporary storage tank.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The thermal hydrolysis temperature of the rural sewage excess sludge thermal hydrolysis treatment equipment and the sludge treatment method of the present invention is relatively low, and the sludge treatment can be carried out at 80°C, which reduces the energy consumption for treating by-products produced during the biochemical reaction of rural sewage and greatly reduces the content of volatile suspended solids in the sludge.

[0031] (2) The present invention utilizes the complementary combination of air heat pump and electric heating to effectively alleviate the problem of insufficient heating capacity of air heat pump above 70°C and excessive power consumption of electric heating; compared with pure electric heating, it can save 60-70% of electricity.

[0032] (3) The sludge thermal hydrolysis treatment of the present invention can effectively reduce the amount of sludge at the site. The supernatant obtained by thermal treatment separation can be reused as a carbon source and coupled with rural sewage treatment equipment to achieve a semi-closed loop utilization of waste and resources.

[0033] (4) The present invention can achieve a VSS removal rate of up to 35% through the combined action of the two-component accelerator EDTA+CaO. In contrast, the removal rate of adding EDTA alone is only 20%, indicating that the two-component combination of the present invention has an excellent sludge treatment effect.

[0034] (5) The EDTA+CaO compound accelerator of the present invention has no corrosive effect on rural sewage sludge treatment equipment, and is cheap, readily available and easy to store.

[0035] (6) The sludge thermal hydrolysis treatment equipment of the present invention is quick, simple and has no secondary pollution, and can realize the in-situ transformation of rural sewage sludge treatment equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of the sludge thermal hydrolysis treatment equipment of the present invention.

[0037] Figure 2 It is a schematic diagram of the removal rate results of SS and VSS in the embodiments of the present invention and the comparative examples.

[0038] Description of the markings in the figure:

[0039] 1-mixing tank, 11-sludge inlet, 12-supernatant discharge port, 13-sludge discharge port;

[0040] 2- Sludge pump;

[0041] 3- Air energy heat pump;

[0042] 4-Electric heating element. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0044] In the present invention, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Unless otherwise specified, the instruments and equipment used in the present invention are conventional instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0046] The sludge treatment methods provided in the following examples and comparative examples are all based on the following rural sewage excess sludge thermal hydrolysis treatment equipment. Figure 1 As shown, the sludge thermal hydrolysis treatment equipment includes a stirring tank 1; a sludge pump 2 connected to the stirring tank 1, used to transport sludge into the stirring tank 1; an air energy heat pump 3 connected to the stirring tank 1, used to provide heat to the stirring tank 1 to raise the temperature inside the tank to 70°C; an electric heating element 4 arranged in the stirring tank 1, used to further provide heat to the stirring tank 1 to maintain the temperature inside the tank at 80°C.

[0047] In some specific implementations, a sludge inlet 11 , a supernatant discharge port 12 and a sludge discharge port 13 are provided on the stirring tank 1 , and an output end of the sludge pump 2 is connected to the sludge inlet 11 .

[0048] In some specific embodiments, the supernatant discharge port 12 is connected to the carbon source addition port of the denitrification tank.

[0049] In some specific implementations, a heat exchange coil is provided in the stirring tank 1, and the air energy heat pump 3 is connected to the heat exchange coil.

[0050] In some specific embodiments, the stirring propeller in the stirring tank 1 includes any one of a turbine stirring propeller, an anchor stirring propeller, a frame stirring propeller or a propeller stirring propeller.

[0051] In some specific embodiments, the material of the stirring tank 1 includes any one of carbon steel or stainless steel.

[0052] Based on the above rural sewage excess sludge thermal hydrolysis treatment equipment, the sludge treatment method of the present invention specifically includes the following steps:

[0053] S1: inputting the rural sewage surplus sludge into the mixing tank under stirring conditions;

[0054] S2: Turn on the air energy heat pump to raise the temperature in the tank to 70°C, then use the electric heating element to raise the temperature and maintain it at 80°C;

[0055] S3: Add EDTA and CaO into the stirring tank in sequence under stirring conditions;

[0056] S4: Natural sedimentation until the sludge and supernatant are separated and then classified and recycled.

[0057] In some specific embodiments, in step S1, the initial stirring speed is 60-80 rpm, and after the sludge rises to a predetermined height, the stirring speed is 120-140 rpm.

[0058] In some specific embodiments, in step S3, the mass ratio of the EDTA feeding amount to the rural sewage excess sludge is (0.02-0.04):1, and after adding EDTA, the stirring speed is increased to 160-180 rpm, and stirring is continued for 30-60 min.

[0059] In some specific implementations, in step S3, the mass ratio of the CaO feeding amount to the rural sewage excess sludge is (0.1-0.2):1, and stirring is continued for 30-60 minutes after adding CaO.

[0060] In some specific embodiments, in step S4, the sedimentation time is 30-60 minutes, the separated supernatant is transported to the denitrification tank, and the separated sludge is discharged into the temporary storage tank.

[0061] The above embodiments can be implemented individually or in any combination of two or more. The above embodiments are described in more detail below with reference to specific examples.

[0062] Embodiment 1:

[0063] The present embodiment provides a rural sewage excess sludge thermal hydrolysis treatment equipment and a corresponding sludge treatment method. Among them, the sludge thermal hydrolysis treatment equipment specifically includes a stirring tank, an air energy heat pump, a sludge pump and an electric heating rod arranged in the tank. The material of the stirring tank is carbon steel, and the stirrer contained in the stirring tank can be frequency-controlled, the stirring speed can be controlled at 60-180rpm, and the stirring paddle type is a turbine type. A sludge discharge port is set at the bottom of the stirring tank, and two supernatant discharge ports are set. The hot water pipe produced by the air energy heat pump is connected to the heat exchange coil in the stirring tank, the sludge pump outlet is connected to the sludge inlet of the stirring tank, and the supernatant discharge port is connected to the carbon source addition port of the denitrification tank of the rural sewage treatment equipment to realize subsequent resource utilization.

[0064] The sludge treatment method of this embodiment is as follows: rural sewage sludge is input into the stirring tank by the sludge pump, the stirring speed is set to 60rpm, and after the sludge liquid level reaches the set height, it is adjusted to 120rpm, and the air energy heat pump is turned on for heating and stirring at the same time. When the temperature in the tank rises to 70°C, it is heated to 80°C by electric heating. When the temperature rises to 80°C and then maintains at 80°C, EDTA is added to the dosing port of the stirring tank, and the ratio of EDTA dosage to rural sewage sludge VSS is 0.02:1. At the same time, the stirring speed is adjusted to 160rpm and stirred for 30 minutes. Subsequently, CaO powder is added, and the ratio of CaO dosage to rural sewage sludge VSS is 0.05:1. After stirring for 30 minutes, the mixer is turned off and precipitated for 30 minutes. The supernatant is discharged to the carbon source addition port of the adjacent rural sewage treatment equipment, and the resulting precipitate is discharged into the temporary storage tank, waiting for the transfer vehicle to be transported to the final disposal site.

[0065] Embodiment 2:

[0066] This comparative example provides a rural sewage excess sludge thermal hydrolysis treatment device and a corresponding sludge treatment method. The difference from Example 1 is that in the sludge treatment method of this example, EDTA is added and stirred for 60 minutes, and CaO is added and stirred for 30 minutes.

[0067] Embodiment 3:

[0068] This comparative example provides a rural sewage excess sludge thermal hydrolysis treatment device and a corresponding sludge treatment method. The difference from Example 1 is that in the sludge treatment method of this example, EDTA is added and stirred for 60 minutes, and CaO is added and stirred for 60 minutes.

[0069] Embodiment 4:

[0070] The present embodiment provides a rural sewage excess sludge thermal hydrolysis treatment equipment and a corresponding sludge treatment method. Among them, the sludge thermal hydrolysis treatment equipment specifically includes a stirring tank, an air energy heat pump, a sludge pump and an electric heating rod arranged in the tank. The material of the stirring tank is carbon steel, and the stirrer contained in the stirring tank can be frequency-controlled, the stirring speed can be controlled at 60-180rpm, and the stirring paddle type is a turbine type. A sludge discharge port is set at the bottom of the stirring tank, and 4 supernatant discharge ports are set to adapt to the discharge of supernatant at different water levels. The hot water pipe produced by the air energy heat pump is connected to the heat exchange coil in the stirring tank, the sludge pump outlet is connected to the sludge inlet of the stirring tank, and the supernatant discharge port is connected to the carbon source addition port of the denitrification tank of the rural sewage treatment equipment to realize subsequent resource utilization.

[0071] The sludge treatment method of this embodiment is as follows: rural sewage sludge is input into the stirring tank by the sludge pump, the stirring speed is set to 80rpm, and after the sludge liquid level reaches the set height, it is adjusted to 140rpm, and the air energy heat pump is turned on for heating and stirring at the same time. When the temperature in the tank rises to 70°C, it is heated to 80°C by electric heating. When the temperature rises to 80°C and is maintained at 80°C, EDTA is added to the dosing port of the stirring tank, and the ratio of EDTA dosage to rural sewage sludge VSS is 0.03:1. At the same time, the stirring speed is adjusted to 180rpm and stirred for 30 minutes. Subsequently, CaO powder is added, and the ratio of CaO dosage to rural sewage sludge VSS is 0.15:1. After stirring for 30 minutes, the mixer is turned off and precipitated for 60 minutes. The supernatant is discharged to the carbon source addition port of the adjacent rural sewage treatment equipment, and the resulting precipitate is discharged into the temporary storage tank, waiting for the transfer vehicle to be transported to the final disposal site.

[0072] Comparative Example 1:

[0073] This comparative example provides a rural sewage excess sludge thermal hydrolysis treatment device and a corresponding sludge treatment method. The difference from Example 1 is that in the sludge treatment method of this comparative example, no CaO powder is added, only EDTA is added and the reaction is stirred for 30 minutes.

[0074] The present invention tests the removal rate of suspended solids (SS) and VSS (volatile suspended solids) on the sludge in the above embodiments and comparative examples. The test method is:

[0075] (1) Place the quantitative filter paper in a clean filtration container and dry it at 105°C until constant weight is obtained. The mass is recorded as a (in g).

[0076] (2) The crucible is burned in a muffle furnace and weighed to a constant value. The mass is recorded as b (in g).

[0077] (3) Take sample V (in mL) and place it in a centrifuge tube. Centrifuge it at 5000 min for 10 minutes. Then place the quantitative filter paper in an aluminum cup and moisten it with distilled water. After filtering the supernatant in the centrifuge tube under suction, transfer the precipitate in the centrifuge tube to the filter paper and wash the centrifuge tube with a little distilled water so that all the precipitate is filtered through the filter paper.

[0078] (4) Dry the filter paper container with the precipitate at 105±2°C to a constant weight, recorded as c (in g).

[0079] (5) Transfer the filter paper and the precipitate in the container to a porcelain crucible and carefully burn it in a fume hood until no smoke is emitted. Then place it in a muffle furnace and burn it at 600°C for 2 h. When the furnace temperature drops to 100°C, take out the crucible, cool it in a desiccator, and weigh it. This is recorded as d (in g).

[0080] The suspended solids (SS) and VSS (volatile suspended solids) removal rates are calculated according to the following formula:

[0081] SS(mg / L)=(ca) / V; VSS(mg / L)=SS-(db) / V.

[0082] The removal rate test results of SS and VSS are as follows: Figure 2 As shown. The results show that when the sludge concentration is 12000 mg / L, the removal rate of VSS can be greatly increased by the combined action of the two-component accelerator of EDTA+CaO, wherein the VSS removal rate of Example 3 can be close to 35%, while the removal rate of Comparative Example 1 in which only EDTA is added is only 20%, indicating that the two-component combined use of the present invention has an excellent sludge treatment effect. In addition, the COD of the supernatant separated after sludge treatment in Example 3 can reach 10000 mg / L, which can be used as a supplement to the carbon source of rural sewage treatment equipment.

[0083] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A rural sewage excess sludge thermal hydrolysis treatment equipment, characterized in that: include: Mixing tank (1); A sludge pump (2) connected to the stirring tank (1) and used for conveying sludge into the stirring tank (1); An air energy heat pump (3) connected to the stirring tank (1) is used to provide heat to the stirring tank (1) to raise the temperature inside the tank to 70° C.; The electric heating element (4) disposed in the stirring tank (1) is used to further provide heat to the stirring tank (1) so as to maintain the temperature inside the tank at 80°C.

2. A rural sewage excess sludge thermal hydrolysis treatment equipment according to claim 1, characterized in that: The stirring tank (1) is provided with a sludge inlet (11), a supernatant discharge port (12) and a sludge discharge port (13), and the output end of the sludge pump (2) is connected to the sludge inlet (11).

3. A rural sewage excess sludge thermal hydrolysis treatment equipment according to claim 2, characterized in that: The supernatant liquid discharge port (12) is connected to the carbon source addition port of the denitrification tank.

4. A rural sewage excess sludge thermal hydrolysis treatment equipment according to claim 1, characterized in that: A heat exchange coil is provided in the stirring tank (1), and the air energy heat pump (3) is connected to the heat exchange coil.

5. A rural sewage excess sludge thermal hydrolysis treatment equipment according to claim 1, characterized in that: The stirring propeller in the stirring tank (1) includes any one of a turbine stirring propeller, an anchor stirring propeller, a frame stirring propeller or a propeller stirring propeller; The material of the stirring tank (1) includes any one of carbon steel or stainless steel; The electric heating element (4) comprises any one or more of an electric heating rod, an electric heating net, and an electric heating film.

6. A sludge treatment method using the rural sewage excess sludge thermal hydrolysis treatment equipment according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: The rural sewage excess sludge is input into a mixing tank (1) under stirring conditions; S2: Turn on the air energy heat pump (3) to raise the temperature in the tank to 70°C, then use the electric heating element (4) to raise the temperature and maintain it at 80°C; S3: adding EDTA and CaO to the stirring tank (1) in sequence under stirring conditions; S4: Natural sedimentation until the sludge and supernatant are separated and then classified and recycled.

7. The sludge treatment method according to claim 6, characterized in that: In step S1, the initial stirring speed is 60-80 rpm, and after the sludge rises to a predetermined height, the stirring speed is 120-140 rpm.

8. The sludge treatment method according to claim 6, characterized in that: In step S3, the mass ratio of the amount of EDTA added to the rural sewage excess sludge is (0.02-0.03):

1. After adding EDTA, the stirring speed is increased to 160-180 rpm, and stirring is continued for 30-60 minutes.

9. The sludge treatment method according to claim 6, characterized in that: In step S3, the mass ratio of the CaO feeding amount to the rural sewage excess sludge is (0.05-0.15):1, and stirring is continued for 30-60 minutes after adding CaO.

10. The sludge treatment method according to claim 6, characterized in that: In step S4, the sedimentation time is 30-60 minutes, the separated supernatant is transported to the denitrification tank, and the separated sludge is discharged into the temporary storage tank.

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