Biological fluidized bed coupled ozone oxidation water purification process for micro-polluted source water

Abstract

The invention provides a biological fluidized bed coupled ozonation water purification system for micro-polluted source water. The biological fluidized bed coupled ozonation water purification system comprises a biological fluidization tank, an ozonation tank and a gas driving tank, the biological fluidization tank, the ozone oxidation tank and the gas driving tank are sequentially connected, a water inlet pipe of the biological fluidization tank is arranged at the lower part and below a filter plate, a water outlet pipe is arranged at the upper part, a cushion layer is arranged above the filter plate in the tank, the cushion layer is composed of multiple layers of cobblestones, two layers of carrier fillers are arranged above the cushion layer, the lower layer is large-particle crushed activated carbon, and the upper layer is biological filler. According to the invention, the biological fluidization tank treatment, the ozone oxidation, the gas driving tank and the conventional treatment process are firstly carried out, ozone plays a role in pre-sterilization after biological treatment, bacteria are prevented from entering a subsequent working section, and the biological treatment coupled ozone oxidation can preferentially degrade organic matters and pre-treat particulate matters, so that the treatment efficiency is improved, and the treatment cost is reduced. And the dissolved oxygen of the effluent is reduced through gas driving, so that the effect of promoting flocculation is achieved, the efficiency of flocculent precipitation is improved, and the pollutant removal capacity of the whole process is further improved.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and in particular relates to a biological fluidized bed coupled ozone oxidation water purification process for slightly polluted water sources. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Surface water has gradually become one of the main sources of drinking water. However, surface water in many areas is polluted to varying degrees, especially organic matter, ammonia nitrogen, turbidity and other indicators are high, which poses a severe test to the conventional drinking water treatment process. Traditional conventional water treatment processes such as flocculation, sedimentation, filtration, disinfection, etc. may have limitations when dealing with some complex pollution problems. It is difficult to effectively remove certain stubborn pollutants. As the degree of pollution increases, the processing capacity and efficiency of conventional treatment processes are increasingly insufficient. In order to overcome the defects of conventional processes, ozone + activated carbon filter process is often used to deeply treat drinking water. Although the efficiency of pollutant removal is improved to a certain extent, the process flow is lengthened, the efficiency improvement is not obvious, and the operating cost increases sharply.

[0004] In order to fundamentally solve the above problems, patent CN115353256A proposes a new process, which uses ozone pre-oxidation tank + biochar tank + high-speed mechanical mixing tank + flocculation sedimentation + filtration process to treat slightly polluted water sources. The ozone pre-oxidation tank + biochar tank is set before the conventional process, which changes the order of removing particulate matter in the water first and then removing organic matter in the traditional process. Organic matter in the water will be removed first and the properties of suspended particles in the water will be changed through pretreatment to achieve the purpose of optimizing flocculation, and then coupled with the conventional process. Compared with the conventional treatment process + deep treatment process, the above method significantly improves the treatment efficiency of organic matter, turbidity, and ammonia nitrogen. However, it was found during the application process that there is still much room for improvement, especially in terms of pollutant removal efficiency and reduced operating costs. Summary of the invention

[0005] In order to further optimize the treatment process of slightly polluted source water, reduce operating costs, and improve pollutant removal efficiency and effluent water quality, the present invention provides a biological fluidized bed coupled ozone oxidation water purification process for slightly polluted source water.

[0006] As a very mature deep water purification process, the ozone-bioactivated carbon process is widely used in major existing surface water plants. However, with the release and implementation of GB5749-2022, a number of new pollutant indicators have been added. The processing capacity of the process is insufficient to meet the new standards. At the same time, people have higher demands for high-quality water, and water supply companies have increasingly stringent requirements on operating costs. There is also a greater demand for new processes that are more energy-saving and consumption-reducing and have higher treatment efficiency. At the same time, during operation, the post-ozone activated carbon process provides higher dissolved oxygen due to ozone, which causes the biofilm on the bioactivated carbon to grow too fast, and backwashing is frequent. The biofilm on the biochar falls off and enters the clear water tank, causing biological leakage. Chlorination cannot effectively kill it, and it is easy to cause the spread of disease after entering the pipeline network. In the present application, biological fluidized bed treatment is first carried out, then ozone oxidation is carried out, and then the conventional treatment process is entered. After the biological treatment, ozone plays a role of pre-sterilization to prevent bacteria from entering the subsequent process stages. A small number of bacteria that enter the subsequent process stages can also be removed through conventional processes. Moreover, biological treatment coupled with ozone oxidation can pre-treat particulate matter, promote flocculation, improve the efficiency of flocculation sedimentation, and thereby improve the overall process's ability to remove pollutants.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water, comprising: a biological fluidized bed tank, an ozone oxidation tank, and a purge tank;

[0009] The biological fluidized bed pool, ozone oxidation pool and degassing pool are connected in sequence. The water inlet pipe of the biological fluidized bed pool is arranged at the lower part and below the filter plate, and the water outlet pipe is arranged at the upper part. A cushion layer is arranged above the filter plate in the pool, and the cushion layer is composed of multiple layers of pebbles. Two layers of carrier fillers are arranged above the cushion layer, the lower layer is large-particle crushed activated carbon, and the upper layer is biological filler.

[0010] In some embodiments, the particle size of the lower layer carrier filler is 1.5 to 2.5 mm, and the thickness is 30 cm to 50 cm.

[0011] In some embodiments, the upper biological filler is coconut shell activated carbon or directional pore-controlled activated carbon.

[0012] In some embodiments, the particle size of the upper biological filler is 0.5-1.0 mm and the thickness is 1.5-2.0 m.

[0013] In some embodiments, the water inlet pipe of the ozone oxidation pool is arranged at the upper part of the pool body, the water outlet pipe and the reflux outlet pipe are arranged at the lower part of the pool body, and a jet aerator is arranged at the bottom of the pool; the ozone oxidation pool can be arranged in grids and run in series;

[0014] In some embodiments, a hydrogen peroxide injection pipeline is provided in the ozone oxidation tank.

[0015] In some embodiments, the reflux outlet pipe of the ozone oxidation tank is connected to a reflux pump and an electromagnetic flowmeter through a pipeline, and the reflux electromagnetic flowmeter operates in conjunction with the reflux pump.

[0016] In some embodiments, the degassing tank is provided with an inlet pipe and an outlet pipe, the inlet pipe is provided at the upper part of the tank body, the outlet pipe is provided at the lower part of the tank body, and an aeration pipe is provided at the bottom of the tank for aeration of the degassing tank.

[0017] The second aspect of the present invention provides a biological fluidized bed coupled ozone oxidation water purification process for slightly polluted water source water, comprising:

[0018] The above system is used to treat slightly polluted source water, which flows through a biological fluidized bed tank, an ozone oxidation tank, and a gas removal tank in sequence;

[0019] Among them, the hydraulic retention time of biological fillers in the biological fluidized bed is 5 to 15 minutes, and the fluidization expansion rate is 30% to 50%;

[0020] The hydraulic retention time of the ozone oxidation pool is 10 to 20 minutes, and the reflux volume is 50% to 200% of the inlet water volume; the sum of the reflux volume and the inlet water volume remains unchanged.

[0021] The gas-water ratio in the aeration pool is 0.5 to 1:1, and the hydraulic retention time is 10 to 20 minutes.

[0022] In some embodiments, the slightly polluted source water passes through a raw water pipeline and merges with a return pipeline of return water, and then enters a biological fluidized bed after passing through a pipeline mixer.

[0023] The third aspect of the present invention provides application of the system in the field of water treatment.

[0024] Beneficial effects of the present invention

[0025] (1) The biological fluidized bed is in direct contact with slightly polluted source water and is also inoculated with surviving microbial populations in the source water, acting as a microbial selector. Here, the adaptation, elimination, optimization, and proliferation of microbial populations are continuously produced, thereby being able to cultivate, domesticate, and induce microbial populations that are adapted to the source water. Some of the microorganisms in the source water are also adsorbed and bonded to the fillers in the fluidized bed, and the nutrients in the source water are directly used by the microorganisms in the fluidized bed. The biochemical fluidized bed has a fast biofilm growth rate. At the same time, the microorganisms in the source water form a symbiotic system with the microorganisms on the fluidized bed fillers, which strengthens the biological action of the source water, improves the biodegradation efficiency, increases the removal rate of pollutants such as organic matter and ammonia nitrogen, and reduces the cost of pollutant removal.

[0026] (2) The biological fluidized bed is in direct contact with slightly polluted water sources. High oxygen-consuming substances in the source water, such as iron and manganese, are directly consumed by organisms in the biological fluidized bed and become elements for biological growth. They no longer enter the subsequent process stages, thus reducing the amount of ozone added in the subsequent process stages due to iron and manganese oxidation.

[0027] (3) The effluent from the biological fluidized bed enters the ozone oxidation tank, which further oxidizes the organic matter in the effluent from the biological fluidized bed that cannot be biologically oxidized, and performs open-loop chain scission or mineralization on the difficult-to-degrade organic matter to improve the biodegradability of the water. The effluent is then returned to the front-end biological fluidized bed tank for biological oxidation, thereby achieving the combination of organic biochemical and advanced oxidation. At the same time, after ozone aeration, the ozone oxidation tank can provide supersaturated dissolved oxygen water, which can be returned to the biological fluidized bed tank to increase biological activity and the biological removal rate of pollutants, reduce the hydraulic retention time of the biological fluidized bed tank, and improve the removal efficiency of organic matter and ammonia nitrogen. Studies have shown that when the hydraulic retention time of supersaturated dissolved oxygen water is 15 minutes, the removal rate of organic matter can reach more than 80%, which is more than 30% higher than that of conventional dissolved oxygen, and the removal rate of ammonia nitrogen can reach more than 95%, which is more than 25% higher than that of conventional dissolved oxygen.

[0028] (4) The effluent from the biological fluidized bed enters the ozone oxidation tank, which can further oxidize the effluent from the biological fluidized bed. After adding hydrogen peroxide, new organic pollutants can also be removed. At the same time, due to the high redox potential of ozone, it has a bactericidal and disinfecting effect, and can sterilize and disinfect the bacteria and microorganisms flowing out of the biological fluidized bed. No bacteria or viruses enter the subsequent treatment unit, preventing the growth of microorganisms in the subsequent treatment unit and improving the precipitation effect.

[0029] (5) Ozone aeration in the ozone oxidation tank provides supersaturated dissolved oxygen water, which has a great promoting effect on the organisms in the front-end biochemical fluidized bed. However, after the supersaturated dissolved oxygen water comes out of the ozone oxidation tank, if it directly enters the subsequent conventional processes such as flocculation and precipitation, studies have shown that under supersaturated dissolved oxygen conditions, polyaluminum chloride coagulant is added. Polyaluminum chloride is an inorganic particle with a hydrophobic and air-friendly surface, which will induce supersaturated gas to condense into bubbles on its surface. Therefore, supersaturated dissolved oxygen will adhere to the flocs and precipitate as bubbles, providing buoyancy for the flocs, affecting the floc precipitation effect, and even causing them to float to form scum. Therefore, the supersaturated dissolved oxygen water coming out of the ozone oxidation tank of the present invention enters the purge tank for purge, reducing the dissolved oxygen in the pretreatment effluent, improving the coagulation and precipitation performance of the subsequent conventional treatment process, improving the removal efficiency of particulate matter, and significantly improving the effluent turbidity.

[0030] (6) The source water and return water are automatically controlled to achieve a stable total flow rate into the biological fluidized bed. The water flow rate of the biological fluidized bed remains constant, its various operating conditions are relatively stable, and the expansion rate remains unchanged; the organic matter in the influent first enters the lower filler area of ​​the biological fluidized bed, and the ozone carried in the return water is decomposed into oxygen under the action of large-particle activated carbon, preventing excessive concentration of ozone from entering the upper biological fluidized filler area, and oxidizing the organic matter in the influent under the catalytic action of activated carbon; the particulate matter in the influent passes through the pores of the lower large-particle activated carbon and enters the upper fluidized layer. The particulate matter flows out of the biological fluidized bed with the rising water flow and enters the subsequent process section; the aged biofilm fragments and worn activated carbon powder shed from the biological fluidized bed also flow out of the biological fluidized bed with the rising water flow and enter the subsequent process section, and then gradually enter the conventional mixed flocculation tank, providing more flocculation cores for the flocculation process and improving the flocculation efficiency.

[0031] (7) The process of the present invention is simple, has a short process flow, is highly practical, and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the exemplary embodiments of the present invention and their description are used to explain the present invention, and do not constitute improper limitations on the present invention.

[0033] Figure 1 The present invention is a schematic diagram of a biological fluidized bed coupled ozone oxidation water purification process for slightly polluted water sources. DETAILED DESCRIPTION

[0034] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] The present invention provides a biological fluidized bed coupled ozone oxidation water purification process for slightly polluted source water, which mainly comprises a biological fluidized bed tank, an ozone oxidation tank and a purge tank, and the three parts are connected in sequence.

[0036] The biological fluidized bed is provided with an inlet pipe and an outlet pipe, the inlet pipe is arranged at the bottom, below the filter plate, the micro-polluted source water passes through the raw water pipe and the return water return pipe, and then enters the biological fluidized bed through the pipe mixer, the raw water pipe and the return water pipe are both provided with electromagnetic flowmeters, the outlet pipe is arranged at the top, a cushion layer is arranged above the filter plate in the pool, the cushion layer is composed of multiple layers of pebbles, the particle size decreases from bottom to top, and two layers of carrier fillers are arranged above the cushion layer, the lower layer is large-particle crushed activated carbon, the particle size is 1.5-2.5mm, the thickness is 30cm-50cm, and the upper layer is biological filler, preferably coconut shell activated carbon or directional pore activated carbon, the particle size is 0.5-1.0mm, and the thickness is 1.5-2.0m. The hydraulic retention time of the biological filler in the biological fluidized bed is 5-15min, and the fluidization expansion rate is 30%-50%.

[0037] The ozone oxidation pool is provided with an inlet pipe, an outlet pipe and a reflux outlet pipe, the inlet pipe is provided at the upper part of the pool body, the outlet pipe and the reflux outlet pipe are provided at the lower part of the pool body, and a jet aerator is provided at the bottom of the pool for ozone aeration; the ozone oxidation pool can be provided in grids and operated in series. A hydrogen peroxide dosing pipe is provided in the ozone oxidation pool, and the hydraulic retention time of the ozone oxidation pool is 10 to 20 minutes.

[0038] The reflux outlet pipe of the ozone oxidation pool is connected to a reflux pump and an electromagnetic flowmeter through a pipeline. The reflux electromagnetic flowmeter and the reflux pump are operated in conjunction with each other. The reflux pump frequency is controlled by the reflux electromagnetic flowmeter and the raw water electromagnetic flowmeter signals to control the reflux volume, so as to keep the sum of the reflux water volume and the raw water volume stable and unchanged. The reflux volume is 50% to 200% of the water inlet volume.

[0039] The aeration pool is provided with an inlet pipe and an outlet pipe, the inlet pipe is provided at the upper part of the pool body, the outlet pipe is provided at the lower part of the pool body, and an aeration pipe is provided at the bottom of the pool for aeration of the aeration pool. The air-water ratio of the aeration pool is 0.5-1:1, and the hydraulic retention time is 10-20 minutes.

[0040] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0041] Example 1

[0042] A biological fluidized bed coupled ozone oxidation water purification process for slightly polluted water sources mainly comprises a biological fluidized bed tank, an ozone oxidation tank and a purge tank, the three parts being connected in sequence.

[0043] The biological fluidized pool is provided with an inlet pipe and an outlet pipe, the inlet pipe is arranged at the bottom, below the filter plate, the micro-polluted source water passes through the raw water pipeline and the return water return pipeline, and then enters the biological fluidized pool after passing through the pipeline mixer, the raw water pipeline and the return water pipeline are both provided with electromagnetic flowmeters, the outlet pipe is arranged at the top, a cushion layer is arranged above the filter plate in the pool, the cushion layer is composed of 3 layers of pebbles, the particle size decreases from bottom to top, and two layers of carrier fillers are arranged above the cushion layer, the lower layer is an ozone catalyst, the particle size is 1.5-2.5mm, the thickness is 50cm, and the upper layer is a biological filler, using coconut shell activated carbon, the particle size is 0.5-1.0mm, and the thickness is 1.5m. The hydraulic retention time of the biological filler in the biological fluidized pool is 15min, and the fluidization expansion rate is 30%.

[0044] The ozone oxidation pool is provided with an inlet pipe, an outlet pipe and a reflux outlet pipe, the inlet pipe is provided at the upper part of the pool body, the outlet pipe and the reflux outlet pipe are provided at the lower part of the pool body, and a jet aerator is provided at the bottom of the pool for ozone aeration; the ozone oxidation pool is divided into three compartments and operated in series. A hydrogen peroxide dosing pipe is provided in the ozone oxidation pool, and the hydraulic retention time of the ozone oxidation pool is 20 minutes.

[0045] The reflux outlet pipe of the ozone oxidation pool is connected to a reflux pump and an electromagnetic flowmeter through a pipeline. The reflux electromagnetic flowmeter and the reflux pump are operated in conjunction with each other. The reflux pump frequency is controlled by the reflux electromagnetic flowmeter and the raw water electromagnetic flowmeter signals to control the reflux volume, so as to keep the sum of the reflux water volume and the raw water volume stable and unchanged. The reflux volume is 50% to 200% of the water inlet volume.

[0046] The aeration pool is provided with an inlet pipe and an outlet pipe, the inlet pipe is provided at the upper part of the pool body, the outlet pipe is provided at the lower part of the pool body, and an aeration pipe is provided at the bottom of the pool for aeration of the aeration pool. The air-water ratio of the aeration pool is 0.5-1:1, and the hydraulic retention time is 10-20 minutes.

[0047] Application Example 1

[0048] The process of Example 1 was adopted to treat a slightly polluted source water (TOC: 5.82 mg / L, ammonia nitrogen 1.09 mg / L, particle number 7368 CNT / ml, turbidity 9.34 NTU), and the effluent entered the high-speed mechanical mixing + flocculation sedimentation + filtration process. The ozone dosage of the ozone oxidation tank was 5 mg / L. After testing, the average effluent TOC was 0.71 mg / L, the average effluent ammonia nitrogen was 0.05 mg / L, the average effluent particle number was 86 CNT / ml, the average effluent turbidity was 0.038 NTU, and the average effluent total bacteria count was 92 CFU / ml. The effluent water quality met and was better than the "Sanitary Standard for Drinking Water (GB5749-2022)".

[0049] Application Example 2

[0050] The process of Example 1 was adopted to treat a slightly polluted source water (TOC: 5.82 mg / L, ammonia nitrogen 1.09 mg / L, particle number 7368 CNT / ml, turbidity 9.34 NTU), and the effluent entered the high-speed mechanical mixing + flocculation sedimentation + filtration process. The ozone dosage of the ozone oxidation tank was 5 mg / L, and the hydrogen peroxide dosage was 2.5 mg / L. After testing, the average effluent TOC was 0.54 mg / L, the average effluent ammonia nitrogen was 0.04 mg / L, the average effluent particle number was 84 CNT / ml, the average effluent turbidity was 0.035 NTU, and the average total effluent bacteria was 86 CFU / ml. The effluent water quality meets and exceeds the "Sanitary Standard for Drinking Water (GB5749-2022)".

[0051] Comparative Example 1

[0052] Ozone pre-oxidation tank + biochar tank + high-speed mechanical mixing tank + flocculation sedimentation + filtration process was used to treat a slightly polluted water source (TOC: 5.82 mg / L, ammonia nitrogen 1.09 mg / L, particle number 7368 CNT / ml, turbidity 9.34 NTU). The ozone dosage of the ozone oxidation tank was 5 mg / L, and other process operating parameters remained the same as those in Application Example 1. After testing, the average effluent TOC was 1.02 mg / L, the average effluent ammonia nitrogen was 0.11 mg / L, the average effluent particle number was 128 CNT / ml, the average effluent turbidity was 0.074 NTU, and the average effluent total bacteria count was 276 CFU / ml.

[0053] Comparative Example 2

[0054] The difference from Application Example 1 is that a "biological fluidized bed tank" is used instead of a "biological fluidized bed tank + ozone oxidation tank + degassing tank" to treat a slightly polluted source water (TOC: 5.82 mg / L, ammonia nitrogen 1.09 mg / L, particle number 7368 CNT / ml, turbidity 9.34 NTU), and the effluent enters a high-speed mechanical mixing + flocculation sedimentation + filtration process. After testing, the average effluent TOC is 1.32 mg / L, the average effluent ammonia nitrogen is 0.22 mg / L, the average effluent particle number is 147 CNT / ml, the average effluent turbidity is 0.089 NTU, and the average total effluent bacteria count is 346 CFU / ml.

[0055] Comparative Example 3

[0056] The difference from Application Example 1 is that a "biological fluidized bed tank + ozone oxidation tank" is used instead of a "biological fluidized bed tank + ozone oxidation tank + purge tank" to treat a slightly polluted source water (TOC: 5.82 mg / L, ammonia nitrogen 1.09 mg / L, particle number 7368 CNT / ml, turbidity 9.34 NTU), and the effluent enters a high-speed mechanical mixing + flocculation sedimentation + filtration process. After testing, the average effluent TOC is 0.74 mg / L, the average effluent ammonia nitrogen is 0.06 mg / L, the average effluent particle number is 138 CNT / ml, the average effluent turbidity is 0.085 NTU, and the average total effluent bacteria count is 234 CFU / ml.

[0057] Comparative Example 4

[0058] The difference from Application Example 2 is that the ozone dosage of the ozone oxidation tank is 0 mg / L, and the hydrogen peroxide dosage is the same as that of Application Example 2. After testing, the average TOC of the effluent is 0.76 mg / L, the average ammonia nitrogen of the effluent is 0.12 mg / L, the average particle count of the effluent is 156 CNT / ml, the average turbidity of the effluent is 0.093 NTU, and the average total bacteria count of the effluent is 147 CFU / ml.

[0059] Through the effluent sampling test results of Example 1, Application Example 1 and Comparative Example 1, it can be found that compared with the traditional ozone-biological activated carbon (O3-BAC) technology, after the pretreatment process provided by the present invention, under the condition of the same ozone dosage, the removal of TOC is significantly improved, and the removal rates of ammonia nitrogen, particulate matter, total bacteria, etc. are all improved to varying degrees.

[0060] Through the effluent sampling test results of Example 1, Application Example 1 and Comparative Examples 2 and 3, it can be found that compared with the "biological fluidized bed tank" treatment and the "biological fluidized bed tank + ozone oxidation tank" treatment, after the treatment process provided by the present invention, under the condition of the same ozone dosage, the TOC removal rate is higher, and the removal rates of ammonia nitrogen, particulate matter, total bacteria count, etc. are all improved to varying degrees.

[0061] Through the test results of the effluent samples of Example 1, Application Examples 1 and 2 and Comparative Example 4, it can be found that compared with the simple ozone treatment or hydrogen peroxide treatment, the combination of the two can significantly improve the TOC removal rate.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water sources, characterized in that: include: Biological fluidized bed tank, ozone oxidation tank, and purge tank; The biological fluidized bed pool, ozone oxidation pool and degassing pool are connected in sequence. The water inlet pipe of the biological fluidized bed pool is arranged at the lower part and below the filter plate, and the water outlet pipe is arranged at the upper part. A cushion layer is arranged above the filter plate in the pool, and the cushion layer is composed of multiple layers of pebbles. Two layers of carrier fillers are arranged above the cushion layer, the lower layer is large-particle crushed activated carbon, and the upper layer is biological filler.

2. The biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water according to claim 1, characterized in that: The particle size of the lower layer carrier filler is 1.5-2.5 mm, and the thickness is 30 cm-50 cm.

3. The biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water according to claim 1, characterized in that: The upper biological filler is coconut shell activated carbon or directional pore-controlled activated carbon.

4. The biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water according to claim 3, characterized in that: The particle size of the upper biological filler is 0.5-1.0 mm, and the thickness is 1.5-2.0 m.

5. The biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water according to claim 1, characterized in that: The water inlet pipe of the ozone oxidation pool is arranged at the upper part of the pool body, the water outlet pipe and the reflux water outlet pipe are arranged at the lower part of the pool body, and a jet aerator is arranged at the bottom of the pool; the ozone oxidation pool can be arranged in grids and run in series; Alternatively, a hydrogen peroxide adding pipeline is provided in the ozone oxidation tank.

6. The biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water according to claim 1, characterized in that: The reflux outlet pipe of the ozone oxidation pool is connected to a reflux pump and an electromagnetic flowmeter through a pipeline, and the reflux electromagnetic flowmeter operates in conjunction with the reflux pump.

7. The biological fluidized bed coupled ozone oxidation water purification system for slightly polluted water source water according to claim 1, characterized in that: The degassing pool is provided with a water inlet pipe and a water outlet pipe, wherein the water inlet pipe is arranged at the upper part of the pool body, the water outlet pipe is arranged at the lower part of the pool body, and an aeration pipe is arranged at the bottom of the pool for aeration of the degassing pool.

8. A biological fluidized bed coupled ozone oxidation water purification process for slightly polluted water sources, characterized in that: include: The system according to any one of claims 1 to 7 is used to treat slightly polluted source water, wherein the slightly polluted source water flows through a biological fluidized bed tank, an ozone oxidation tank, and a purge tank in sequence; Among them, the hydraulic retention time of biological fillers in the biological fluidized bed is 5 to 15 minutes, and the fluidization expansion rate is 30% to 50%; The hydraulic retention time of the ozone oxidation pool is 10 to 20 minutes, and the return flow is 50% to 200% of the inlet water volume; The gas-water ratio in the aeration pool is 0.5 to 1:1, and the hydraulic retention time is 10 to 20 minutes.

9. The biological fluidized bed coupled ozone oxidation water purification process for slightly polluted water source water according to claim 8, characterized in that: The slightly polluted source water passes through the raw water pipe and merges with the return water return pipe, then passes through the pipe mixer and enters the biological fluidized bed tank.

10. Use of the system according to any one of claims 1 to 7 in the field of water treatment.

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