Municipal sludge treatment method and stabilization equipment based on microwave catalytic oxidation technology

Abstract

The invention relates to a municipal sludge treatment method and stabilization equipment based on a microwave catalytic oxidation technology, and belongs to the field of sludge treatment. The problems that a municipal sludge biological stabilization method is too long in treatment time, low in treatment efficiency and incomplete in treatment are solved. The equipment comprises a belt conveyor, a microwave cavity and a microwave magnetron. The method comprises the following steps: adding a composite additive (10-30 parts of activated carbon, 30-40 parts of biochar and 15-25 parts of rice hull ash) according to 1-8% of the dry basis mass of sludge; stage 1, microwave treatment (the frequency is 915 / 2450MHz, the power density is 3-5W / g, and the temperature is kept at 100-120 DEG C for 1-3min); in the second stage, microwave treatment is carried out, the frequency is 915 / 2450 MHz, the power density is 1-2 W / g, and heat preservation is carried out for 5-12 min at the temperature of 60-80 DEG C. According to the stabilization scheme, the treatment time is shortened to 15 min, the power consumption per ton is 42 kWh, and finally air drying is carried out till the water content is 1t; and the product meets the recycling safety standard.

Description

Technical Field

[0001] The present invention relates to the technical field of sludge treatment, and in particular to a municipal sludge treatment method and stabilization equipment based on microwave catalytic oxidation technology. Background Art

[0002] In the field of municipal sludge treatment, traditional treatment methods often suffer from low treatment efficiency, high energy consumption, and unstable treatment results. With the acceleration of urbanization, the amount of municipal sludge generated continues to increase, and the requirements for treatment technology are becoming increasingly higher.

[0003] Defects of existing sludge stabilization technology:

[0004] 1. Microwave single treatment: The temperature inside the sludge rises unevenly, the sterilization rate is less than 90%, and it takes more than 20 minutes;

[0005] 2. Chemical oxidation method: requires high temperature (>80℃) to activate the oxidant, which consumes a lot of energy and produces toxic by-products;

[0006] 3. Traditional biological stabilization technology: The composting cycle is usually greater than 20 days, and the amount of odor released is large;

[0007] 4. Thermal drying: high cost, excessive decomposition of organic matter, carbonization of humic acid, and reduced resource utilization in the later stage;

[0008] Therefore, it is particularly important to develop a municipal sludge treatment equipment that is efficient, energy-saving, environmentally friendly and easy to operate. Summary of the Invention

[0009] The purpose of the present invention is to solve the problems of long treatment time, low treatment efficiency and incomplete treatment in the municipal sludge biological stabilization method, and to propose a municipal sludge treatment method and stabilization equipment based on microwave catalytic oxidation technology.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] The municipal sludge treatment method based on microwave catalytic oxidation technology includes the following steps:

[0012] S1. Crushing the sludge from the sewage treatment plant and uniformly mixing the composite additives according to 1-8% of the dry mass of the sludge; the composite additives include:

[0013] 10-30 parts of activated carbon, 30-40 parts of one or a mixture of at least two of agricultural and forestry waste, medicinal residue, and biochar, and 15-25 parts of rice husk ash;

[0014] The biochar was pretreated by 1 mol / L KOH activation and 0.1 mol / LFeCl3 impregnation;

[0015] S2. putting the materials in S1 into a municipal sludge treatment device using microwave catalytic oxidation technology and starting a microwave magnetron to irradiate a mixture of the composite additive and the sludge;

[0016] S3, stage 1 microwave treatment: frequency 2450 MHz or 915 MHz, power density 3-5 W / g, heating to 100-120 ° C, hold for 1-3 min;

[0017] S4, stage 2 microwave treatment: frequency 915 MHz or 2450 MHz, power density 1-2 W / g, cooling to 60-80 ° C, holding for 5-12 min;

[0018] S5. The discharged material is air-dried until the moisture content is less than 30% to obtain a stabilized product.

[0019] In one possible design, the microwave frequencies of stage 1 and stage 2 are independently selected as 915 MHz or 2450 MHz, and the combination is one of the following: 915 MHz / 915 MHz, 2450 MHz / 915 MHz, 915 MHz / 2450 MHz or 2450 MHz / 2450 MHz.

[0020] The stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology is used in the above-mentioned sludge treatment method, comprising: a belt conveyor, a feed hopper and a discharge hopper are respectively installed on both sides of the top of the belt conveyor, a microwave cavity is installed on the top of the belt conveyor, a microwave magnetron is installed on the microwave cavity, a moisture exhaust pipe and a heat exhaust pipe are installed on the top of the microwave cavity, microwave suppressors are installed at the entrance and exit of the microwave cavity, and the belt conveyor passes through the microwave suppressor and enters the microwave cavity.

[0021] Preferably, the municipal sludge treatment stabilization equipment based on microwave catalytic oxidation technology comprises two sets, which are arranged in an upper and lower layer manner or in a horizontal series manner.

[0022] Preferably, the discharge hopper of one of the two sets of municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper of the other one.

[0023] Preferably, the discharge hopper of the upper-layer municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper of the lower-layer municipal sludge stabilization equipment based on microwave catalytic oxidation technology through a guide trough.

[0024] Preferably, the discharge hopper of the first section of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper of the second section of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology through a conveyor.

[0025] Beneficial effects:

[0026] The municipal sludge treatment method based on microwave catalytic oxidation technology has achieved: sterilization rate > 99% (traditional microwave technology < 90%); electricity consumption per ton of sludge is reduced to 42kWh, which is 70% lower than the traditional thermochemical method (> 150kWh); stabilization time is shortened to ≤ 15 minutes, which is nearly 2,000 times more efficient than traditional composting (> 480 hours); in terms of deodorization rate, the degradation rate of sulfur-containing organic matter is > 95%, and the NH3 release is reduced by 90%; the product resource value is high, the seed germination index (GI) is > 80%, and the heavy metal leaching toxicity is strictly lower than the GB5085.3 limit, with five advantages: efficient sterilization, energy saving and consumption reduction, rapid stability, source deodorization and safe resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a single device for the stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology proposed in the present invention;

[0028] Figure 2 Schematic diagram for the upper and lower layers arrangement;

[0029] Figure 3 This is a schematic diagram of the horizontal series arrangement.

[0030] In the figure: 1. Feed hopper; 2. Microwave suppressor; 3. Belt conveyor; 4. Microwave cavity; 5. Discharge hopper; 6. Dehumidification pipe; 7. Heat exhaust pipe; 8. Microwave magnetron; 9. Conveyor; 10. Conveyor. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] In one embodiment: refer to Figure 1-3 The stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology includes: a belt conveyor 3, a feed hopper 1 and a discharge hopper 5 are respectively installed on both sides of the top of the belt conveyor 3, a microwave cavity 4 is installed on the top of the belt conveyor 3, multiple microwave magnetrons 8 are installed on the top of the microwave cavity 4, a moisture removal pipe 6 and a heat removal pipe 7 are installed on the top of the microwave cavity 4, microwave suppressors 2 are installed at the entrance and exit of the microwave cavity 4, and the belt conveyor 3 passes through the microwave suppressor 2 to enter the microwave cavity 4.

[0033] It also includes a waveguide tube, one end of which is connected to the microwave magnetron 8, and the other end of the waveguide tube is connected to a microwave feed port, which is arranged on the microwave cavity 4, and microwaves are fed into the microwave cavity 4 through the microwave feed port.

[0034] The microwave cavity 4 is provided with a microwave suppressor 2 at both the feed port and the discharge port. The microwave suppressor 2 is used to block microwave leakage, and its waveguide attenuation value is ≥30dB, ensuring the safe operation of the microwave system in industrial production.

[0035] Furthermore, the stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology consists of two sets, which are arranged in an upper and lower layer or in a horizontal series manner (the upper layer can be 915MHz or 2450MHz, the lower layer can also be 915MHz or 2450MHz, the first section can be 915MHz or 2450MHz, and the second section can also be 915MHz or 2450MHz).

[0036] Furthermore, the discharge hopper 5 of one of the two sets of municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper 1 of the other one.

[0037] Furthermore, the discharge hopper 5 of the upper layer of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper 1 of the lower layer of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology through a guide trough 9.

[0038] Furthermore, the discharge hopper 5 of the first section of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper 1 of the second section of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology through a conveyor 10 (such as a belt conveyor or a screw conveyor, etc.).

[0039] The municipal sludge treatment method based on microwave catalytic oxidation technology includes the following steps:

[0040] S1. Crushing the sludge from the sewage treatment plant with a water content of 80%, and uniformly mixing the composite additive according to 1-8% of the dry mass of the sludge; the composite additive comprises:

[0041] 10-30 parts of activated carbon, 30-40 parts of one or a mixture of at least two of agricultural and forestry waste, medicinal residue, and biochar, and 15-25 parts of rice husk ash;

[0042] The biochar was pretreated by 1 mol / L KOH activation and 0.1 mol / LFeCl3 impregnation;

[0043] S2, the material in S1 is put into the feed hopper 1, and is sent into the microwave cavity 4 via the belt conveyor 3 for heating, and the microwave magnetron 8 is started to generate microwaves to achieve microwave radiation, irradiating the mixture of the composite additive and the sludge, and finally discharged from the discharge hopper 5;

[0044] S3, phase 1 microwave treatment: frequency 2450 MHz or 915 MHz, power density 3-5 W / g, temperature rise to 100-120℃, hold for 1-3 min;

[0045] S4, phase 2 microwave treatment: frequency 915 MHz or 2450 MHz, power density 1-2 W / g, temperature drop to 60-80℃, hold for 5-12 min;

[0046] S5, discharge and air dry to moisture content <30%, obtain stabilized product.

[0047] The microwave frequencies of phase 1 and phase 2 are independently selected from 915 MHz or 2450 MHz, and the combination is one of the following: 915 MHz / 915 MHz, 2450 MHz / 915 MHz, 915 MHz / 2450 MHz, or 2450 MHz / 2450 MHz.

[0048] In another embodiment: 1 ton of sludge with moisture content 80% (dry basis mass 200 kg), add 16 kg of composite additive (3.2 kg of activated carbon + 5.6 kg of straw biochar + 3.2 kg of rice husk ash); phase 1 microwave: 2450 MHz / 4 W / g, 105℃ / 2 min → fecal coliforms ≤100 MPN / g; phase 2 microwave: 915 MHz / 1.5 W / g, 70℃ / 8 min → H2S release ≤0.5 ppm, organic matter decomposition rate ≥85%.

[0049] In another embodiment: use 915 MHz + 915 MHz combination scheme: phase 1: 4.8 W / g, 105℃, 2.7 min; phase 2: 1.2 W / g, 70℃, 10.3 min; additive ratio A:B:C = 15:35:20, total time consumption 13 min, ton electricity consumption 44 kWh.

[0050] The following table is the parameter of the four schemes:

[0051]

[0052] In the above table: additive A is activated carbon, B is one or a mixture of at least two of agricultural and forestry waste, medicinal residue, and biochar, and C is rice husk ash; the biochar is activated by 1 mol / L KOH and impregnated with 0.1 mol / L FeCl3.

[0053] The following table is the data of the four schemes:

[0054] parameter Solution 1 Option 2 Option 3 Option 4 Stage 1 Power 4.8W / g 10.3W / g 3.3W / g 12.6W / g Phase 2 Time 10.3min 11.7min 8.2min 7.2min Activated carbon ratio 15 servings 22 servings 14 servings 26 servings Ton of electricity consumption 44kWh 63kWh 52kWh 71kWh

[0055] However, those skilled in the art can understand that the microwave magnetron 8 includes a magnetron body, a heat sink, and a power module, and its installation manner is not limited to the position shown in the figure.

[0056] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A municipal sludge treatment method based on microwave catalytic oxidation technology, characterized in that: The following steps are involved: S1. Crushing the sludge from the sewage treatment plant and uniformly mixing the composite additives according to 1-8% of the dry mass of the sludge; the composite additives include: 10-30 parts of activated carbon, 30-40 parts of one or a mixture of at least two of agricultural and forestry waste, medicinal residue, and biochar, and 15-25 parts of rice husk ash; The biochar was pretreated by 1 mol / L KOH activation and 0.1 mol / LFeCl3 impregnation; S2, putting the material in S1 into a municipal sludge treatment device using microwave catalytic oxidation technology and starting a microwave magnetron (8) to irradiate a mixture of the composite additive and the sludge; S3, stage 1 microwave treatment: frequency 2450 MHz or 915 MHz, power density 3-5 W / g, heating to 100-120 ° C, hold for 1-3 min; S4, stage 2 microwave treatment: frequency 915 MHz or 2450 MHz, power density 1-2 W / g, cooling to 60-80 ° C, holding for 5-12 min; S5. The discharged material is air-dried until the moisture content is less than 30% to obtain a stabilized product.

2. The method according to claim 1, wherein: The microwave frequencies of the stage 1 and the stage 2 are independently selected to be 915 MHz or 2450 MHz, and the combination is one of the following: 915 MHz / 915 MHz, 2450 MHz / 915 MHz, 915 MHz / 2450 MHz or 2450 MHz / 2450 MHz.

3. A stabilization device for municipal sludge treatment based on microwave catalytic oxidation technology, used in the sludge treatment method according to claim 1, characterized in that: include: A belt conveyor (3) is provided, wherein a feed hopper (1) and a discharge hopper (5) are respectively installed on both sides of the top of the belt conveyor (3), a microwave cavity (4) is installed on the top of the belt conveyor (3), a microwave magnetron (8) is installed on the microwave cavity (4), a moisture removal pipe (6) and a heat removal pipe (7) are installed on the top of the microwave cavity (4), microwave suppressors (2) are installed at the entrance and exit of the microwave cavity (4), and the belt conveyor (3) passes through the microwave suppressor (2) and enters the microwave cavity (4).

4. The stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology according to claim 3 is characterized in that: The municipal sludge treatment stabilization equipment based on microwave catalytic oxidation technology comprises two sets, which are arranged in an upper and lower layer manner or in a horizontal series manner.

5. The stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology according to claim 4 is characterized in that: The discharge hopper (5) of one of two sets of municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper (1) of the other one.

6. The stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology according to claim 5 is characterized in that: The discharge hopper (5) of the upper layer of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper (1) of the lower layer of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology through a guide trough (9).

7. The stabilization equipment for municipal sludge treatment based on microwave catalytic oxidation technology according to claim 5 is characterized in that: The discharge hopper (5) of the first section of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology is connected to the feed hopper (1) of the second section of the municipal sludge stabilization equipment based on microwave catalytic oxidation technology through a conveyor (10).

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