A heterogeneous Fenton fluidized bed process and its sludge recycling method and recovery device

Abstract

The present invention discloses a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, comprising the following steps: (1) adding iron-carbon composite powder and hydrogen peroxide to wastewater for full reaction; (2) the effluent of the Fenton reaction tank enters a catalyst selector to screen the iron-carbon composite powder therein; (3) the wastewater enters a neutralization flocculation sedimentation tank for neutralization flocculation sedimentation to produce iron-containing precipitated sludge; (4) the precipitated sludge is prepared into iron-carbon composite powder; (5) the iron-carbon composite powder catalyst is transported to a catalyst selector, and after screening by the catalyst selector, it is added to the Fenton reaction tank to participate in the reaction. The heterogeneous Fenton fluidized bed process and the sludge recycling method thereof of the present invention use iron-carbon composite powder with a particle size of less than 150 μm to replace the granular catalyst, which can greatly increase the reaction rate, reduce the reaction time and the reactor volume; and the equipment investment cost and the operating cost are significantly reduced, the process flow is more simplified, the yield is higher, and it is more suitable for large-scale sewage and sludge treatment project applications.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a heterogeneous Fenton fluidized bed process and a sludge recycling method and a recovery device thereof. Background Art

[0002] The Fenton process is a commonly used advanced oxidation wastewater treatment process. Through the catalytic effect of divalent iron ions on hydrogen peroxide, highly oxidizing hydroxyl radicals (·OH) are produced to oxidize and decompose organic matter that is difficult to treat with other processes. Among all advanced oxidation processes, the Fenton process has the advantages of simple operation and small equipment investment. However, the addition of divalent iron ions to wastewater produces additional waste sludge, which greatly increases the sludge disposal cost of the Fenton process.

[0003] The heterogeneous Fenton process is an improvement on the Fenton process. It uses an iron-containing solid catalyst to catalyze the reaction with hydrogen peroxide, avoiding the addition of ferrous sulfate to the water, thereby reducing the amount of iron-containing sludge produced. However, since the reaction of the heterogeneous Fenton process is usually carried out under acidic conditions, the iron element in the catalyst will gradually be consumed, and iron-containing sludge will still be produced. In addition, as the iron element is consumed, the catalyst particles need to be replaced regularly, which also adds additional costs.

[0004] Chinese patent CN110040901A discloses a micro-electrolysis / heterogeneous Fenton fluidized bed process and device for sludge reuse, which uses porous carbon-loaded iron particles with a particle diameter of 0.5 to 3 mm as catalyst fluidized particles to treat wastewater in a fluidized bed reactor with bottom inlet and top outlet, and prepares the iron-containing sludge produced by it into porous iron-carbon particles / porous carbon-loaded iron particles, which are re-entered into the fluidized bed reactor to participate in the reaction, thereby realizing the recycling of iron-containing sludge or even zero emission. However, in the fluidized bed process disclosed by patent CN110040901A, a baffle is set in the fluidized bed reactor for intercepting the catalyst fluidized particles, and a magnetic separation device is used to recover the carbon-loaded iron particles flowing out of the reactor, and in the process of recycling the iron-containing sludge, the remaining biochemical sludge is mixed and an adhesive is added for granulation and screening before carbonization and reuse. The whole process flow is long, the required equipment structure is complex, and the parameter range control requirements are high, resulting in high investment costs and operating costs. Therefore, solving the above problems will be conducive to the wider application and promotion of the heterogeneous Fenton fluidized bed process and its sludge recycling technology. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a heterogeneous Fenton fluidized bed process and a sludge recycling method and a recovery device thereof.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

[0007] The first aspect of the present invention is to provide a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, comprising the following steps:

[0008] (1) adding iron-carbon composite powder to wastewater in a Fenton reaction tank, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst to fully mix with hydrogen peroxide for reaction;

[0009] (2) The effluent from the Fenton reaction tank enters the catalyst selector to screen the iron-carbon composite powder therein, and the screened iron-carbon composite powder flows back from the bottom to the Fenton reaction tank to continue the reaction;

[0010] (3) The wastewater after screening by the catalyst selector enters the subsequent neutralization flocculation sedimentation tank for neutralization flocculation sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0011] (4) re-preparing the iron-containing precipitated sludge produced by the neutralization and flocculation into an iron-carbon composite powder as a heterogeneous Fenton catalyst;

[0012] (5) The re-prepared iron-carbon composite powder catalyst is transported to the catalyst selector, and after being screened by the catalyst selector, it is added to the Fenton reaction tank to participate in the reaction.

[0013] Furthermore, in the heterogeneous Fenton fluidized bed process and the sludge recycling method thereof, the particle size of the iron-carbon composite powder in step (1) is less than 150 μm, and the iron content is greater than 20%.

[0014] Furthermore, in the heterogeneous Fenton fluidized bed process and the sludge recycling method thereof, the mass of the iron-carbon composite powder added in step (1) is 1 to 20% of the mass of the wastewater in the Fenton reaction tank.

[0015] Furthermore, in the heterogeneous Fenton fluidized bed process and the sludge recycling method thereof, in step (1), mechanical stirring or aeration stirring is used to carry out a sufficient mixing reaction in the Fenton reaction tank.

[0016] Further preferably, in the heterogeneous Fenton fluidized bed process and the sludge reuse method thereof, for the small Fenton reaction tank, a paddle stirrer or a perforated aeration tube is used for stirring; for the large Fenton reaction tank, a jet aeration device is used for stirring.

[0017] Furthermore, in the heterogeneous Fenton fluidized bed process and its sludge reuse method, the catalyst selector in step (2) is an elongated conical bottom container, with water entering from the bottom and discharging from the top, and the bottom of the cone refluxes the screened iron-carbon composite powder into the Fenton reaction tank through a catalyst reflux pump.

[0018] Furthermore, in the heterogeneous Fenton fluidized bed process and the sludge reuse method thereof, the neutralization flocculation sedimentation tank in step (3) comprises a pH neutralization stirring tank, a flocculation stirring tank and a sedimentation tank.

[0019] Furthermore, in the heterogeneous Fenton fluidized bed process and the sludge recycling method thereof, the iron-containing precipitated sludge in step (4) is sequentially subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment to prepare an iron-carbon composite powder.

[0020] Further preferably, in the heterogeneous Fenton fluidized bed process and the sludge reuse method thereof, the pyrolysis temperature of the high temperature pyrolysis is 500-800°C, and the sludge is crushed to less than 150 μm after pyrolysis.

[0021] Furthermore, in the heterogeneous Fenton fluidized bed process and its sludge reuse method, the iron-carbon composite powder re-prepared in step (5) is added to the catalyst selector through a powder delivery pump via a pipeline mixer, and after being screened by the catalyst selector, it is replenished into the Fenton reaction tank by a catalyst reflux pump at the bottom to participate in the reaction.

[0022] The second aspect of the present invention is to provide a heterogeneous Fenton fluidized bed process and a sludge recycling device, comprising:

[0023] A Fenton reaction tank for fully mixing wastewater and catalyst;

[0024] a catalyst selector for screening the catalyst in the effluent of the Fenton reaction tank, wherein the bottom of the catalyst selector is connected to the Fenton reaction tank via a catalyst reflux pump to transport the screened catalyst to the Fenton reaction tank for further reaction; and

[0025] A neutralization flocculation sedimentation tank is used to neutralize and flocculate the wastewater passing through the catalyst selector. The bottom of the neutralization flocculation sedimentation tank is connected to the catalyst selector via a sludge recycling device to re-prepare the iron-containing precipitated sludge produced by the neutralization flocculation sedimentation tank into a catalyst and transport it to the catalyst selector.

[0026] Furthermore, in the heterogeneous Fenton wastewater treatment and sludge recycling device, the catalyst is an iron-carbon composite powder, the particle size of the iron-carbon composite powder is less than 150 μm, and the iron content is greater than 20%.

[0027] Furthermore, in the heterogeneous Fenton wastewater treatment and sludge reuse device, an agitator is arranged in the Fenton reaction tank, and the agitator is a mechanical agitator or an aeration agitator.

[0028] Further preferably, in the heterogeneous Fenton wastewater treatment and sludge reuse device, the mechanical agitator is a paddle agitator; and the aeration agitator is a perforated aeration tube or a jet aerator.

[0029] Furthermore, in the heterogeneous Fenton wastewater treatment and sludge recycling device, the catalyst selector is an elongated conical bottom container, the middle of which is connected to the Fenton reaction tank, the upper part is connected to the neutralization flocculation sedimentation tank, and the bottom is connected to a catalyst reflux pump.

[0030] Furthermore, in the heterogeneous Fenton wastewater treatment and sludge recycling device, the neutralization flocculation sedimentation tank comprises a pH neutralization stirring tank, a flocculation stirring tank and a sedimentation tank connected in sequence, the upper part of the pH neutralization stirring tank is connected to the catalyst selector, and the bottom of the sedimentation tank is connected to the sludge recycling device.

[0031] Furthermore, in the heterogeneous Fenton wastewater treatment and sludge recycling device, the sludge recycling device comprises a sludge tank, a feed pump, a sludge dewatering machine, a sludge drying machine, a sludge carbonization machine, a pulverizer and a silo arranged in sequence, and the silo is connected to the catalyst selector through a powder conveying pump.

[0032] Further preferably, in the heterogeneous Fenton wastewater treatment and sludge reuse device, a pipeline mixer is provided on the water inlet pipeline from the Fenton reaction tank to the catalyst selector, and the pipeline mixer is connected to the powder delivery pump.

[0033] The present invention adopts the above technical solution, which has the following technical effects compared with the prior art:

[0034] (1) Using iron-carbon composite powder with a particle size of less than 150 μm to replace granular catalyst can greatly increase the reaction rate and reduce the reaction time and reactor volume;

[0035] (2) The device structure is simpler, easy to operate and maintain, and the equipment investment cost and operating cost can be significantly reduced, which has obvious economic advantages;

[0036] (3) The process of preparing catalysts by recycling sludge is simpler, with higher yield, and is more suitable for large-scale sewage and sludge treatment projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a process flow chart of a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof;

[0038] Wherein, each figure is marked as:

[0039] 1-Fenton reaction tank, 2-catalyst selector, 3-pH neutralization stirring tank, 4-flocculation stirring tank, 5-sedimentation tank, 6-catalyst reflux pump, 7-sludge tank, 8-feed pump, 9-sludge dewatering machine, 10-sludge drying machine, 11-sludge carbonization machine, 12-crusher, 13-silo, 14-powder conveying pump, 15-pipeline mixer. DETAILED DESCRIPTION

[0040] See also Figure 1 As shown, the present invention provides a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof to improve the reaction efficiency of the existing heterogeneous Fenton process, reduce production costs, and achieve large-volume processing, including the following steps:

[0041] (1) adding iron-carbon composite powder to the wastewater in the Fenton reaction tank 1, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst to fully mix and react with hydrogen peroxide to replace or reduce the addition of ferrous sulfate;

[0042] (2) The effluent from the Fenton reaction tank 1 enters the catalyst selector 2 to screen the iron-carbon composite powder, and the screened iron-carbon composite powder flows back from the bottom to the Fenton reaction tank to continue the reaction;

[0043] (3) The wastewater after screening by the catalyst selector 2 enters the subsequent neutralization flocculation sedimentation tank for neutralization flocculation sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0044] (4) re-preparing the iron-containing precipitated sludge produced by the neutralization and flocculation into an iron-carbon composite powder as a heterogeneous Fenton catalyst;

[0045] (5) The re-prepared iron-carbon composite powder catalyst is transported to the catalyst selector 2, and after being screened by the catalyst selector, it is added to the Fenton reaction tank to participate in the reaction.

[0046] As a preferred technical solution, the particle size of the iron-carbon composite powder in step (1) is less than 150 μm, and the iron content is greater than 20%; the mass of the iron-carbon composite powder added is 1 to 20% of the mass of the wastewater in the Fenton reaction tank.

[0047] As a preferred technical solution, in step (1), mechanical stirring or aeration stirring is used to fully mix the reaction in the Fenton reaction tank. For a small Fenton reaction tank 1, a paddle stirrer or a perforated aeration tube is used for stirring; and for a large Fenton reaction tank 1, a jet aeration device is used for stirring.

[0048] As a preferred technical solution, the catalyst selector 2 in step (2) is an elongated conical bottom container, with water entering from the bottom and discharging from the top, and the catalyst reflux pump 6 at the bottom of the cone refluxes the screened iron-carbon composite powder into the Fenton reaction tank 1.

[0049] As a preferred technical solution, the neutralization flocculation sedimentation tank in step (3) comprises a pH neutralization stirring tank 3, a flocculation stirring tank 4 and a sedimentation tank 5, wherein: the neutralization stirring tank 3 is provided with a stirrer, a pH meter and a liquid alkali dosing device, the flocculation stirring tank 4 is provided with a stirrer and a flocculant dosing device, and the sedimentation tank 5 can be selected in various forms such as vertical flow, horizontal flow or radial flow according to specific circumstances. If necessary, inclined plates, inclined tubes and other structures can be set in the sedimentation tank to enhance the sedimentation effect.

[0050] As a preferred technical solution, the iron-containing precipitated sludge in step (4) is sequentially subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment to prepare an iron-carbon composite powder. The high temperature cracking process allows the presence of oxygen and does not require strict anaerobic conditions. The cracking temperature of the high temperature cracking is 500-800°C, and the powder is crushed to less than 150 μm after cracking.

[0051] As a preferred technical solution, the iron-carbon composite powder re-prepared in step (5) is added to the catalyst selector through a powder delivery pump via a pipeline mixer, and after being screened by the catalyst selector, it is replenished into the Fenton reaction tank by a catalyst reflux pump at the bottom to participate in the reaction.

[0052] Please continue reading Figure 1 As shown, the present invention provides a heterogeneous Fenton process and a device for sludge recycling thereof, comprising: a Fenton reaction tank 1 for fully mixing wastewater and catalyst; a catalyst selector 2 for screening the catalyst in the effluent of the Fenton reaction tank 1, the bottom of the catalyst selector 2 is connected to the Fenton reaction tank 1 through a reflux pump 6, so as to transport the screened catalyst to the Fenton reaction tank 1 for continuing the reaction; and a neutralization flocculation sedimentation tank for neutralizing and flocculating the wastewater passing through the catalyst selector 2, the bottom of the neutralization flocculation sedimentation tank is connected to the catalyst selector 2 through a sludge recycling device, so as to re-prepare the iron-containing precipitated sludge produced in the neutralization flocculation sedimentation tank into a catalyst and transport it to the catalyst selector 2.

[0053] As a preferred technical solution, please continue to refer to Figure 1As shown, the Fenton reaction tank 1 is provided with a stirrer, and the stirrer is a mechanical stirrer or an aeration stirrer in various forms. The mechanical stirrer is a paddle stirrer; the aeration stirrer is a perforated aeration tube or a jet aerator. Specifically, a paddle stirrer or a perforated aeration tube can be used for a small Fenton reaction tank 1, and a jet aerator is preferably used for stirring for a large Fenton reaction tank 1.

[0054] As a preferred technical solution, please continue to refer to Figure 1 As shown, the catalyst selector 2 is a slender cone-bottom container, the lower part of which is connected to the Fenton reaction tank 1, and the upper part is connected to the neutralization flocculation sedimentation tank. The neutralization flocculation sedimentation tank comprises a pH neutralization stirring tank 3, a flocculation stirring tank 4 and a sedimentation tank 5 which are connected in sequence. The upper part of the pH neutralization stirring tank 3 is connected to the catalyst selector 2, and a stirrer, a pH meter and a liquid alkali dosing device are arranged in the pH neutralization stirring tank 3, a stirrer and a flocculant dosing device are arranged in the flocculation stirring tank 4, and various forms such as vertical flow, horizontal flow or radial flow are selected in the sedimentation tank 5 according to specific conditions. If necessary, inclined plates, inclined tubes and other structures can be arranged in the sedimentation tank to enhance the sedimentation effect.

[0055] As a preferred technical solution, please continue to refer to Figure 1 As shown, the sludge recycling device comprises a sludge pool 7, a feed pump 8, a sludge dewatering machine 9, a sludge drying machine 10, a sludge carbonizing machine 11, a crusher 12 and a silo 13 arranged in sequence. The sludge recycling device converts the iron-containing sludge into an iron-carbon composite powder, which is specifically achieved through a series of processes of "mechanical dehydration-drying-high temperature cracking-crushing". The prepared catalyst powder is stored in the silo 13, and the silo 13 is connected to the catalyst selector 2 through a powder delivery pump 14. After screening, the catalyst selector 2 returns the screened catalyst powder to the heterogeneous Fenton reaction tank 1 to participate in the reaction for repeated use. A pipeline mixer 15 is provided between the Fenton reaction tank 1 and the catalyst selector 2, and the pipeline mixer 15 is connected to the powder delivery pump 14, and the powder is added to the pipeline mixer 15 on the water inlet pipeline of the catalyst selector 2 through the powder delivery pump 14.

[0056] Compared with the solution in patent CN110040901A, the present invention provides a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, which uses iron-carbon composite powders less than 150 μm to replace iron-carbon composite particles of 0.5 to 3 mm. Due to the reduction in the size of the catalyst particles, the contact area with the wastewater increases, and the reaction rate of the catalyst is proportional to the contact area, while the contact area is inversely proportional to the square of the catalyst size. When powder is used instead of particles as a catalyst, due to the size effect, the reaction rate will be increased by at least 10 times, so that the reactor volume required to achieve the same reaction effect can be shortened to one-tenth of the original; or in other words, under the same reactor volume, the amount of catalyst required can be reduced to one-tenth of the original; at the same time, due to the reduction in the amount of catalyst or the reduction in the reactor volume, the stirring power required for catalyst fluidization can also be proportionally reduced.

[0057] Compared with the solution in patent CN110040901A, the present invention provides a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, which uses a catalyst screener with a bottom-in and top-out slender cone bottom to screen and recycle the catalyst powder. The screener uses the difference in specific gravity of the catalyst powder to discharge the excess carbon powder in the catalyst powder with the rising water flow, while the iron element powder with a higher specific gravity flows back into the fluidized bed reactor. Compared with the magnetic separation equipment used in the original solution, it has a simple structure, convenient maintenance, no additional energy consumption, low cost, and simple operation and maintenance.

[0058] Compared with the solution in patent CN110040901A, the present invention provides a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof. When the iron-containing sludge is recycled to prepare the catalyst, no additional adhesive is added, and no granulation and screening are performed. Instead, the sludge is directly dried and cracked before being crushed. Compared with the sludge recycling method of the original solution, the kneading machine, granulator and screening equipment are omitted, and only one crushing equipment is added. The overall equipment investment is small, the output is large, the energy consumption is low, and the operation and maintenance are convenient.

[0059] In summary, the heterogeneous Fenton fluidized bed process and sludge recycling method adopted by the present invention have the advantages of higher reaction efficiency, less equipment investment, lower operating cost, simpler and more convenient operation and maintenance, etc., compared with the solution of the comparative patent CN110040901A. Taking the construction of a fluidized bed device and sludge recycling system that treats 200 tons of wastewater per day and produces 1 ton of sludge per day as an example, the comparison of the investment and operating costs of the technical solution of the present patent and the technical solution described in patent CN110040901A is shown in Table 1.

[0060] Table 1 Investment and operating costs

[0061]

[0062]

[0063] The present invention is described in detail and specifically by specific examples below to provide a better understanding of the present invention, but the following examples do not limit the scope of the present invention.

[0064] Example 1

[0065] This embodiment treats a high-concentration chemical wastewater by using an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 20% as a heterogeneous Fenton catalyst, and adopts a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, including the following steps:

[0066] (1) taking an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 20%, adding the iron-carbon composite powder to the wastewater in the Fenton reaction tank 1 at a rate of 20% of the mass of the wastewater, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst and hydrogen peroxide to fully mix and react by mechanical stirring;

[0067] (2) The effluent from the Fenton reaction tank 1 enters the catalyst selector 2 to screen the iron-carbon composite powder. The screened iron-carbon composite powder is transported from the bottom of the Fenton reaction tank 1 through a catalyst reflux pump 6 through a pipeline to continue the reaction;

[0068] (3) The wastewater after being screened by the catalyst selector 2 enters the subsequent pH neutralization stirring tank 3, flocculation stirring tank 4 and sedimentation tank 5 in sequence for neutralization, flocculation and sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0069] (4) The iron-containing precipitated sludge produced by the above neutralization and flocculation is discharged from the sedimentation tank 5 to the sludge tank 7, and is successively subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment by the sludge dewatering machine 9, the sludge drying machine 10, the sludge carbonizing machine 11 and the crushing machine 12, and then re-prepared into an iron-carbon composite powder as a heterogeneous Fenton catalyst, and stored in a silo 13. The cracking temperature of the high temperature cracking is 500° C., and the sludge is not strictly anaerobic. After cracking, the sludge is crushed into an iron-carbon composite powder with a particle size of <150 μm;

[0070] (5) The iron-carbon composite powder catalyst re-prepared in the above-mentioned silo 13 is added to the catalyst selector 1 through the powder delivery pump 14 and the pipeline mixer 15. After being screened by the catalyst selector 2, it is replenished into the Fenton reaction tank 1 through the catalyst reflux pump 6 at the bottom thereof to participate in the reaction.

[0071] Example 2

[0072] This embodiment treats a high-concentration chemical wastewater by using an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 30% as a heterogeneous Fenton catalyst, and adopts a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, including the following steps:

[0073] (1) Weighing an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 30%, adding the iron-carbon composite powder to the wastewater in the Fenton reaction tank 1 at a rate of 10% of the mass of the wastewater, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst and hydrogen peroxide to fully mix and react by mechanical stirring;

[0074] (2) The effluent from the Fenton reaction tank 1 enters the catalyst selector 2 to screen the iron-carbon composite powder. The screened iron-carbon composite powder is transported from the bottom of the Fenton reaction tank 1 through a catalyst reflux pump 6 through a pipeline to continue the reaction;

[0075] (3) The wastewater after being screened by the catalyst selector 2 enters the subsequent pH neutralization stirring tank 3, flocculation stirring tank 4 and sedimentation tank 5 in sequence for neutralization, flocculation and sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0076] (4) The iron-containing precipitated sludge produced by the above neutralization and flocculation is discharged from the sedimentation tank 5 to the sludge tank 7, and is successively subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment by the sludge dewatering machine 9, the sludge drying machine 10, the sludge carbonizing machine 11 and the crushing machine 12, and then is re-prepared into an iron-carbon composite powder as a heterogeneous Fenton catalyst and stored in a silo 13. The cracking temperature of the high temperature cracking is 500° C., and the anaerobic environment is strictly avoided. After cracking, the sludge is crushed into an iron-carbon composite powder with a particle size of <150 μm;

[0077] (5) The iron-carbon composite powder catalyst re-prepared in the above-mentioned silo 13 is added to the catalyst selector 1 through the powder delivery pump 14 and the pipeline mixer 15. After being screened by the catalyst selector 2, it is replenished into the Fenton reaction tank 1 through the catalyst reflux pump 6 at the bottom thereof to participate in the reaction.

[0078] Example 3

[0079] This embodiment treats a high-concentration chemical wastewater by using an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 40% as a heterogeneous Fenton catalyst, and adopts a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, including the following steps:

[0080] (1) Weighing an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 40%, adding the iron-carbon composite powder to the wastewater in the Fenton reaction tank 1 at 1% of the mass of the wastewater, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst and hydrogen peroxide to fully mix and react by mechanical stirring;

[0081] (2) The effluent from the Fenton reaction tank 1 enters the catalyst selector 2 to screen the iron-carbon composite powder. The screened iron-carbon composite powder is transported from the bottom of the Fenton reaction tank 1 through a catalyst reflux pump 6 through a pipeline to continue the reaction;

[0082] (3) The wastewater after being screened by the catalyst selector 2 enters the subsequent pH neutralization stirring tank 3, flocculation stirring tank 4 and sedimentation tank 5 in sequence for neutralization, flocculation and sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0083] (4) The iron-containing precipitated sludge produced by the above neutralization and flocculation is discharged from the sedimentation tank 5 to the sludge tank 7, and is successively subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment by the sludge dewatering machine 9, the sludge drying machine 10, the sludge carbonizing machine 11 and the crushing machine 12, and then is re-prepared into an iron-carbon composite powder as a heterogeneous Fenton catalyst and stored in a silo 13. The cracking temperature of the high temperature cracking is 650° C., and the sludge is not strictly anaerobic. After cracking, the sludge is crushed into an iron-carbon composite powder of less than 150 μm;

[0084] (5) The iron-carbon composite powder catalyst re-prepared in the above-mentioned silo 13 is added to the catalyst selector 1 through the powder delivery pump 14 and the pipeline mixer 15. After being screened by the catalyst selector 2, it is replenished into the Fenton reaction tank 1 through the catalyst reflux pump 6 at the bottom thereof to participate in the reaction.

[0085] Example 4

[0086] This embodiment treats a high-concentration chemical wastewater by using an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 50% as a heterogeneous Fenton catalyst, and adopts a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, including the following steps:

[0087] (1) Weighing an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 50%, adding the iron-carbon composite powder to the wastewater in the Fenton reaction tank 1 at 5% of the mass of the wastewater, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst and hydrogen peroxide to fully mix and react by mechanical stirring;

[0088] (2) The effluent from the Fenton reaction tank 1 enters the catalyst selector 2 to screen the iron-carbon composite powder. The screened iron-carbon composite powder is transported from the bottom of the Fenton reaction tank 1 through a catalyst reflux pump 6 through a pipeline to continue the reaction;

[0089] (3) The wastewater after being screened by the catalyst selector 2 enters the subsequent pH neutralization stirring tank 3, flocculation stirring tank 4 and sedimentation tank 5 in sequence for neutralization, flocculation and sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0090] (4) The iron-containing precipitated sludge produced by the above neutralization and flocculation is discharged from the sedimentation tank 5 to the sludge tank 7, and is successively subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment by the sludge dewatering machine 9, the sludge drying machine 10, the sludge carbonizing machine 11 and the crushing machine 12, and then re-prepared into an iron-carbon composite powder as a heterogeneous Fenton catalyst, and stored in a silo 13. The cracking temperature of the high temperature cracking is 800° C., and the sludge is not strictly anaerobic. After cracking, the sludge is crushed into an iron-carbon composite powder with a particle size of <150 μm;

[0091] (5) The iron-carbon composite powder catalyst re-prepared in the above-mentioned silo 13 is added to the catalyst selector 1 through the powder delivery pump 14 and the pipeline mixer 15. After being screened by the catalyst selector 2, it is replenished into the Fenton reaction tank 1 through the catalyst reflux pump 6 at the bottom thereof to participate in the reaction.

[0092] Example 5

[0093] This embodiment treats a high-concentration chemical wastewater by using an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 30% as a heterogeneous Fenton catalyst, and adopts a heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, including the following steps:

[0094] (1) Weighing an iron-carbon composite powder with a particle size of less than 150 μm and an iron content of 30%, adding the iron-carbon composite powder to the wastewater in the Fenton reaction tank 1 at a rate of 15% of the mass of the wastewater, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst and hydrogen peroxide to fully mix and react by mechanical stirring;

[0095] (2) The effluent from the Fenton reaction tank 1 enters the catalyst selector 2 to screen the iron-carbon composite powder. The screened iron-carbon composite powder is transported from the bottom of the Fenton reaction tank 1 through a catalyst reflux pump 6 through a pipeline to continue the reaction;

[0096] (3) The wastewater after being screened by the catalyst selector 2 enters the subsequent pH neutralization stirring tank 3, flocculation stirring tank 4 and sedimentation tank 5 in sequence for neutralization, flocculation and sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged;

[0097] (4) The iron-containing precipitated sludge produced by the above neutralization and flocculation is discharged from the sedimentation tank 5 to the sludge tank 7, and is successively subjected to mechanical dehydration-drying-high temperature cracking-crushing treatment by the sludge dewatering machine 9, the sludge drying machine 10, the sludge carbonizing machine 11 and the crushing machine 12, and then re-prepared into an iron-carbon composite powder as a heterogeneous Fenton catalyst, and stored in a silo 13. The cracking temperature of the high temperature cracking is 750° C., and the sludge is not strictly anaerobic. After cracking, the sludge is crushed into an iron-carbon composite powder with a particle size of <150 μm;

[0098] (5) The iron-carbon composite powder catalyst re-prepared in the above-mentioned silo 13 is added to the catalyst selector 1 through the powder delivery pump 14 and the pipeline mixer 15. After being screened by the catalyst selector 2, it is replenished into the Fenton reaction tank 1 through the catalyst reflux pump 6 at the bottom thereof to participate in the reaction.

[0099] Performance Test:

[0100] The wastewater treatment effects of the above-mentioned embodiments 1-5 of the present invention were tested respectively, and the three indicators of COD, chromaticity, and B / C were compared and analyzed. The specific test results are shown in Table 2 below:

[0101] Table 2 Wastewater treatment test results

[0102] Serial number COD removal rate Chroma removal rate B / C improvement value Example 1 55％ 84％ 0.19→0.44 Example 2 58％ 85％ 0.19→0.45 Example 3 61％ 88％ 0.19→0.46 Example 4 63％ 89％ 0.19→0.48 Example 5 61％ 88％ 0.19→0.47

[0103] Combined with the test data shown in Table 2 above, it can be seen that increasing the iron content can also increase the COD, chromaticity removal rate and B / C ratio. In Example 4, the treatment effect is best when the iron content is 50%; the COD and chromaticity removal rates are better when the mass ratio of the Fenton reaction tank particles increases; when the iron-containing sludge is reused and cracked at 800°C, the COD, chromaticity removal rate and B / C ratio of the treated wastewater of the heterogeneous Fenton catalyst particles are the highest. Therefore, from the perspective of performance, Example 4 is the most preferred solution.

[0104] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A heterogeneous Fenton fluidized bed process and a sludge recycling method thereof, characterized in that: Includes steps: (1) Adding iron-carbon composite powder to the wastewater in the Fenton reaction tank, and using the iron-carbon composite powder as a heterogeneous Fenton catalyst to fully mix with hydrogen peroxide for reaction; (2) The effluent from the Fenton reaction pool enters the catalyst selector to screen the iron-carbon composite powder therein, and the screened iron-carbon composite powder flows back from the bottom to the Fenton reaction pool to continue the reaction; (3) The wastewater after screening by the catalyst selector enters the subsequent neutralization flocculation sedimentation tank for neutralization flocculation sedimentation to produce iron-containing sedimentation sludge, and the supernatant is discharged; (4) re-preparing the iron-containing precipitated sludge produced by the neutralization and flocculation into an iron-carbon composite powder as a heterogeneous Fenton catalyst; (5) transporting the re-prepared iron-carbon composite powder catalyst to the catalyst selector, and adding it to the Fenton reaction tank to participate in the reaction after being screened by the catalyst selector; Wherein, the particle size of the iron-carbon composite powder in step (1) is less than 150 μm, and the iron content is greater than 20%; In step (1), mechanical stirring or aeration stirring is used to carry out a sufficient mixing reaction in the Fenton reaction tank; The catalyst selector is an elongated cone-bottom container, the middle of which is connected to the Fenton reaction tank, the upper part is connected to the neutralization flocculation sedimentation tank, and the bottom is connected to a catalyst reflux pump.

2. The heterogeneous Fenton fluidized bed process and sludge recycling method thereof according to claim 1, characterized in that: The mass of the iron-carbon composite powder added in step (1) is 1 to 20% of the mass of the wastewater in the Fenton reaction tank.

3. The heterogeneous Fenton fluidized bed process and sludge recycling method thereof according to claim 1, characterized in that: The iron-containing precipitated sludge in step (4) is sequentially subjected to mechanical dehydration, drying, high-temperature cracking and pulverization to prepare an iron-carbon composite powder.

4. The heterogeneous Fenton fluidized bed process and sludge recycling method thereof according to claim 3, characterized in that: The pyrolysis temperature of the high temperature pyrolysis is 500-800°C, and the particles are crushed to less than 150 μm after pyrolysis.

5. The heterogeneous Fenton fluidized bed process and sludge recycling method thereof according to claim 1, characterized in that: The iron-carbon composite powder prepared again in step (5) is added to the catalyst selector through a powder delivery pump via a pipeline mixer, and after being screened by the catalyst selector, it is replenished into the Fenton reaction tank by a catalyst reflux pump at the bottom thereof to participate in the reaction.

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