Two-stage ozone biological fluidized bed water purification system and process

Abstract

The present application belongs to the technical field of water supply treatment, and belongs to a two-stage ozone biological fluidized bed water purification treatment system and process. According to the flow direction of raw water, the system comprises a first-stage ozone oxidation tank, a first-stage biological fluidized bed, a second-stage ozone oxidation tank and a second-stage biological fluidized bed in sequence. The first-stage ozone oxidation tank comprises an outer tank body and an inner tank body. The outer tank body is closed and provided with a water inlet and a water outlet at the upper part. A sludge collection area is arranged at the bottom of the outer tank body. The inner tank body is suspended in the outer tank body and the top of the inner tank body is higher than the water outlet of the outer tank body. A channel between the side wall of the outer tank body and the side wall of the inner tank body is arranged as a sedimentation area. A first ozone aeration device is arranged in the lower part of the inner tank body. The flow direction of raw water in the first-stage ozone oxidation tank is ozone oxidation area, sedimentation area and water outlet in sequence. The purpose of the present application is to provide a two-stage ozone biological fluidized bed water purification treatment system and process. The water purification treatment system and process provided by the present application can remove pollutants in raw water in depth.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and relates to a two-stage ozone biological fluidized bed water purification system and process. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With the development of industrial and agricultural economies, the concentrations of recalcitrant pollutants, ammonia nitrogen, and odor-causing substances in surface water sources have been increasing year by year. Traditional water purification processes such as coagulation, sedimentation, filtration, and disinfection have very limited effectiveness in removing recalcitrant organic matter, ammonia nitrogen, and odor-causing substances. This results in high concentrations of pollutants remaining in the effluent from water treatment plants, which not only affects the taste of drinking water but also poses potential health hazards. For example, some recalcitrant organic matter has carcinogenic, teratogenic, and mutagenic effects, while odor-causing substances such as geosmin (GSM) and 2-methylisoborneol (2-MIB) can cause unpleasant odors in drinking water, reducing public acceptance of drinking water quality.

[0004] Currently, commonly used advanced ozone removal processes mainly include ozone-hydrogen peroxide advanced oxidation, ozone catalytic oxidation, ozone-biological activated carbon, and ozone-biological fluidized bed processes. All of these ozone-related processes have good removal effects. However, with increasingly complex source water quality, the operating costs of existing ozone-based processes are constantly increasing, while the removal efficiency is limited and difficult to improve further. Moreover, they are prone to generating byproducts, resulting in the effluent still containing high concentrations of recalcitrant pollutants, ammonia nitrogen, odor substances, and byproducts.

[0005] Therefore, developing a highly efficient water purification process for removing pollutants such as recalcitrant organic matter, ammonia nitrogen, turbidity, and odor substances from relatively heavily polluted water sources is of significant practical importance. Summary of the Invention

[0006] To address the problems of low removal efficiency of recalcitrant organic matter, odor substances, and ammonia nitrogen in existing water purification processes when treating contaminated surface water sources, the present invention aims to provide a two-stage ozone biological fluidized bed water purification system and process. The water purification system and process provided by the present invention can achieve deep removal of pollutants in source water (raw water).

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In the first aspect, a two-stage ozone biological fluidized bed water treatment system is used to be installed at the front end of a conventional water treatment system (coagulation + sedimentation + filtration + disinfection) to pretreat raw water; the system includes a primary ozone oxidation tank, a primary biological fluidized bed, a secondary ozone oxidation tank, and a secondary biological fluidized bed in sequence according to the flow direction of the raw water. The primary ozone oxidation tank includes an outer tank and an inner tank. The outer tank is enclosed and has an inlet and an outlet at its upper part. The inlet is connected to the inner tank via a pipe. A sludge collection area is set at the bottom of the outer tank. The inner tank is a cylindrical structure with open upper and lower ends and is suspended inside the outer tank. The top of the inner tank is higher than the water surface of the primary ozone oxidation tank. The channel between the side walls of the outer tank and the inner tank is set as a sedimentation area with a sedimentation structure. The inner tank is an ozone oxidation zone. A first ozone aeration device is set at the lower part of the ozone oxidation zone. The flow direction of the raw water in the primary ozone oxidation tank is ozone oxidation zone, sedimentation zone, and outlet in sequence. Both the primary and secondary biological fluidized beds are enclosed structures, and each contains a fluidized layer filled with packing material and activated carbon. The secondary ozone oxidation tank is also enclosed and contains a second ozone aeration device and a hydrogen peroxide dosing device. The first and second ozone aeration devices are connected to an ozone source, and the hydrogen peroxide dosing device is connected to a hydrogen peroxide source.

[0008] Due to the continuously increasing concentration of organic matter in some water sources, the organic matter encapsulates inorganic particles in the water, reducing the hydrophilicity and increasing the hydrophobicity of the inorganic particles, causing them to remain suspended in the water and making it difficult for them to form flocs and settle during the mixing and flocculation process. This invention incorporates an inner tank within the primary ozone oxidation tank as an ozone oxidation zone. By introducing ozone, the organic matter on the surface of the inorganic particles is oxidized under ozone oxidation, thereby restoring the hydrophilicity and flocculation properties of the inorganic particles. The particles then undergo sedimentation in a settling zone, achieving separation of the particles from the water. Simultaneously, the ozone oxidation zone and the settling zone are separated by the inner tank, preventing ozone bubbles from entering the settling zone, reducing interference with the settling process, and facilitating the sedimentation and separation of particles in the settling zone.

[0009] In some implementations, the sedimentation structure is an inclined plate and / or an inclined tube. This sedimentation structure has a high sedimentation load, which can significantly improve the separation and removal efficiency of particulate matter.

[0010] In some implementation schemes, the primary biological fluidized bed is a closed tank structure with an inlet at the bottom and an outlet at the top. By controlling the water flow direction through the inlet and outlet, it is beneficial to maintain the fluidization state of the packing material within the fluidized bed.

[0011] In some implementation schemes, the primary biological fluidized bed consists of a uniform water distribution zone, a support layer, and a fluidized layer from bottom to top. The water distribution zone and support layer serve to support the fluidized layer packing material and also facilitate uniform water distribution. The fluidized layer is filled with porous packing material, providing a carrier for microbial attachment and growth.

[0012] In some implementation schemes, the secondary ozone oxidation tank has an inlet at the top and an outlet at the bottom. By controlling the water flow direction through the inlet and outlet, a counter-current gas-liquid contact between ozone and water is formed. This results in a high concentration gradient at the gas-liquid interface, a fast mass transfer rate, and the maintenance of a high concentration of dissolved ozone in the water, thereby improving ozone utilization efficiency. Furthermore, the sufficient contact between dissolved ozone and dissolved organic matter in the water facilitates further advanced treatment of pollutants in the raw water.

[0013] In some implementation schemes, the secondary biological fluidized bed is a closed tank structure with an inlet at the bottom and an outlet at the top. By controlling the water flow direction through the inlet and outlet, it is beneficial to maintain the fluidized state of the packing material within the fluidized bed and to deeply treat pollutants in the raw water.

[0014] In some implementation schemes, the secondary biological fluidized bed consists of a uniform water distribution zone, a support layer, and a fluidized layer from bottom to top. The water distribution zone and support layer serve to support the fluidized layer packing material and also facilitate uniform water distribution. The fluidized layer is filled with porous packing material, providing a carrier for microbial attachment and growth.

[0015] In some implementation schemes, an ozone destructor is installed at the top of the primary ozone oxidation tank. This decomposes unused ozone and prevents air pollution.

[0016] In some implementation schemes, an ozone exhaust gas destroyer is installed at the top of the primary biological fluidized bed.

[0017] In some implementations, an ozone destructor is installed at the top of the secondary ozone oxidation tank. This decomposes unused ozone and prevents air pollution.

[0018] In some implementation schemes, an ozone exhaust gas destroyer is installed at the top of the secondary biological fluidized bed.

[0019] In some implementation schemes, the activated carbon filled in the primary biological fluidized bed is coal-based activated carbon, and the activated carbon filled in the secondary biological fluidized bed is coconut shell activated carbon. The source water first passes through a primary ozone oxidation tank, then enters a primary biological fluidized bed, then a secondary ozone oxidation tank, and finally the secondary biological fluidized bed. After ozone oxidation and particulate matter sedimentation, the naturally occurring microorganisms in the source water attach to the surface and internal pores of the activated carbon in the primary biological fluidized bed. At this point, the source water has a large number and variety of microorganisms, which attach rapidly. Moreover, the naturally occurring microorganisms in the source water have long-term contact with organic matter in the water source, forming a specific food chain, which can more effectively remove most of the organic matter in the source water. The water entering the secondary biological fluidized bed has a lower concentration of organic matter, and most of it consists of intermediate products from ozone oxidation. After being oxidized by high-concentration ozone in the secondary ozone oxidation tank, the number of microorganisms is relatively small. During the operation of the secondary biological fluidized bed, a microbial population that is specifically designed for the removal of intermediate products and growth under low concentrations of organic matter gradually forms. Since coal-based activated carbon and coconut shell activated carbon have different sources and preparation processes, the two types of activated carbon have significant differences in characteristics. Coal-based activated carbon has a smaller specific surface area and porosity but a larger density, while coconut shell activated carbon has a larger specific surface area and porosity but a smaller density. This invention, by adjusting the activated carbon filling in different biological fluidized beds, is beneficial to controlling the distribution of microbial populations in the biological fluidized beds. Studies have shown that the system under this setting can better remove organic matter from source water.

[0020] On the other hand, a two-stage ozone biological fluidized bed water purification process provides the above-mentioned two-stage ozone biological fluidized bed water purification system, in which raw water is sequentially fed into a primary ozone oxidation tank, a primary biological fluidized bed, a secondary ozone oxidation tank, and a secondary biological fluidized bed for treatment.

[0021] In some implementation schemes, the ozone dosage in the primary ozone oxidation tank is 0.5~2 mg / L; the hydraulic retention time in the ozone oxidation zone is 5~20 min.

[0022] In some implementation schemes, the ozone dosage in the secondary ozone oxidation tank is 2-5 mg / L, and the hydrogen peroxide dosage is 0-2 mg / L; the hydraulic retention time is 5-20 min.

[0023] In some implementation schemes, the ratio of ozone dosage in the primary ozone oxidation tank to that in the secondary ozone oxidation tank is 1:3 to 8. Studies have shown that this condition results in better treatment of source water.

[0024] Thirdly, the application of the above-mentioned two-stage ozone biological fluidized bed water purification system or two-stage ozone biological fluidized bed water purification process in treating slightly polluted water sources into drinking water.

[0025] The principle of this invention is as follows: When the two-stage ozone biological fluidized bed water purification system of the present invention is in operation, raw water enters the ozone reaction zone from the upper part of the primary ozone oxidation tank. Ozone is added to the lower part of the ozone reaction zone through the first ozone aeration device. Ozone and raw water form gas-water convection in the ozone reaction zone, and ozone and raw water fully contact and react. The effluent then enters the sedimentation zone from the bottom of the ozone reaction zone. The sedimentation zone is equipped with a sedimentation structure, which separates large-diameter particles such as algae, aquatic plants, and silt from the raw water. The water enters the outlet from the upper part of the sedimentation structure and is discharged from the primary ozone oxidation tank. The effluent from the primary ozone oxidation tank is then discharged into the primary ozone oxidation tank by gravity or by a water pump. The water enters the primary biological fluidized bed, where the bottom is filled with a pebble support layer and an appropriate amount of granular activated carbon. The activated carbon is fluidized under the action of water flow, and then exits the primary biological fluidized bed through the upper outlet to enter the secondary ozone oxidation tank. In the secondary ozone oxidation tank, the water further reacts with ozone and hydrogen peroxide, and then exits the secondary ozone oxidation tank through the upper outlet. The effluent enters the secondary biological fluidized bed through gravity flow or pressurization by a water pump. The bottom of the secondary biological fluidized bed is filled with a pebble support layer and an appropriate amount of granular activated carbon. The activated carbon is fluidized under the action of water flow, and then exits the secondary biological fluidized bed through the upper outlet.

[0026] This invention is a water purification process integrating ozone oxidation, advanced ozone oxidation, ozone catalytic oxidation, cavitation, and biological oxidation. It is placed upstream of conventional raw water treatment processes (coagulation + sedimentation + filtration + disinfection). Raw water first enters the primary ozone oxidation reaction tank, where ozone reacts with pollutants. Due to the diverse types of pollutants in the raw water, there is competition for reactions between different pollutants. Pollutants easily oxidized by ozone, such as microbial pollutants (bacteria, viruses, algae, etc.), reducing inorganic pollutants (ferrous iron, manganese, sulfides, etc.), and highly reactive organic pollutants (phenols, alkenes, etc.), are preferentially oxidized and removed by ozone in the ozone reaction zone of the primary ozone oxidation tank before entering the sedimentation zone. Large particles such as algae, silt, and shells are removed in the sedimentation zone. The effluent from the primary ozone oxidation tank is then introduced into the primary biological fluidized bed via gravity flow or pump pressurization after passing through the upper outlet. The primary biological fluidized bed is filled with high-hardness wear-resistant packing material and activated carbon. The packing material and activated carbon are fluidized under the action of water flow. The effluent from the primary ozone oxidation tank contains extremely high dissolved oxygen, providing favorable conditions for the growth and reproduction of microorganisms. Microorganisms attach to and grow on the surface of the packing material and in the internal pores, degrading ammonia nitrogen, small molecule organic matter, and reducing substances such as iron, manganese, and sulfides in the water through biological action. The primary ozone biological fluidized bed mainly plays a role in biodegradation, while recalcitrant organic matter such as odor substances, pesticides, and antibiotics enter the secondary ozone biological fluidized bed with the effluent.

[0027] In the secondary ozone oxidation tank, cavitation jet aerators are used for ozone aeration, and hydrogen peroxide is added simultaneously. Under the action of ozone, the hydrogen peroxide generates active groups such as hydroxyl radicals. These active groups oxidize, decompose, and partially mineralize odor-causing substances, pesticides, and antibiotics. Simultaneously, the cavitation jet aerators generate localized temperatures of over 1000 degrees Celsius during the cavitation process, oxidizing extremely low concentrations of recalcitrant organic matter to achieve ultimate removal of organic matter. The effluent from the secondary ozone oxidation tank, after passing through the upper outlet, enters the secondary biological fluidized bed via gravity flow or pump pressurization. The bed is filled with high-hardness, wear-resistant packing material, which is fluidized under the action of water flow. The effluent from the secondary ozone oxidation tank contains ultra-high dissolved oxygen, providing favorable conditions for the growth and reproduction of microorganisms. Microorganisms attach to and grow on the surface of the packing material and in the internal pores. Through biological action, they further degrade large-molecule recalcitrant organic matter into small-molecule organic matter and ammonia nitrogen after oxidation and decomposition by free radicals and cavitation. The secondary ozone oxidation tank mainly plays a role in advanced oxidation and mineralization. The secondary biological fluidized bed is mainly enriched with special oligotrophic bacteria that degrade recalcitrant organic matter and its decomposed organic matter.

[0028] Beneficial effects of the present invention (1) The two-stage ozone biological fluidized bed water purification process provided by the present invention adopts a graded treatment form. In the first stage, it mainly plays the role of settling large particles and using biodegradation to remove small molecule organic matter, ammonia nitrogen, iron and manganese and other reducing substances, thereby reducing the subsequent ozone consumption. In the second stage, cavitation aeration is adopted and hydrogen peroxide is added. Cavitation and free radical action are used to oxidize and decompose odor substances, pesticides, antibiotics and other difficult-to-degrade organic matter and achieve partial mineralization. Then, the biological action of the second-stage biological fluidized bed is used to carry out extreme degradation of the oxidized and decomposed organic matter. Different pollutants in the water source are graded and treated in the most suitable way. This solves the problems of large ozone dosage, low ozone utilization rate and difficulty in improving oxidation efficiency in conventional first-stage ozone biological fluidized bed. (2) The two-stage ozone biological fluidized bed water purification process provided by the present invention integrates ozone oxidation, ozone advanced oxidation, ozone catalytic oxidation, cavitation and biological oxidation into one water purification process. It is placed at the front end of the conventional treatment process (coagulation + sedimentation + filtration + disinfection) and can achieve deep removal of recalcitrant organic matter. Compared with the conventional single-stage ozone biological fluidized bed, the removal rate of recalcitrant organic matter such as odor substances, pesticides, antibiotics and ammonia nitrogen can be increased by 30-40%, and the ozone dosage can be reduced by 20-30%.

[0029] (3) The two-stage ozone biological fluidized bed water purification process provided by this invention has two independent biological fluidized beds. Each stage can cultivate its own unique microbial community suitable for the water quality characteristics of that stage. The distribution of microbial communities in the two-stage biological fluidized beds is richer and more targeted. The microbial community in the first-stage biological fluidized bed is mostly eutrophic, which is suitable for degrading easily biodegradable substances. The microbial community in the second-stage biological fluidized bed is mostly oligotrophic, which is suitable for degrading difficult-to-biodegrade substances and their oxidative decomposition intermediates. Therefore, the microbial community structure in the two-stage biological fluidized bed is richer and more targeted in degradation. The microorganisms in each stage can better adapt to different substrates and environmental conditions, which is conducive to improving the stability of the treatment system's operation.

[0030] (4) The two-stage ozone biological fluidized bed water purification process provided by the present invention can be applied to most surface water source water plants. It is highly practical and has broad application prospects. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a flow chart of the two-stage ozone biological fluidized bed water purification process in Embodiment 1 of the present invention; The system comprises: 1. Inlet; 2. Ozone reaction zone; 3. Sedimentation zone; 4. First ozone aeration device; 5. Sludge collection zone; 6. Ozone tail gas destroyer; 7. Booster pump; 8. Primary biological fluidized bed; 9. Secondary ozone reaction tank; 10. Secondary biological fluidized bed; 11. Hydrogen peroxide dosing system; 12. Secondary ozone aeration device; 13. Ozone dosing system; and 14. Outlet. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Slightly polluted source water is a technical term in the water treatment field, referring to source water whose quality indicators exceed the requirements of drinking water source hygiene standards due to the influence of discharged industrial wastewater and domestic sewage. In rivers, this manifests as levels of ammonia nitrogen, total phosphorus, color, and organic matter exceeding drinking water source hygiene standards. In lakes and reservoirs, it manifests as eutrophication, with algae growth occurring at certain times, leading to water quality deterioration and a significant increase in odor.

[0036] In view of the problems of low removal efficiency of recalcitrant organic matter, odor substances and ammonia nitrogen in existing water purification processes when treating polluted surface water sources, this invention proposes a two-stage ozone biological fluidized bed water purification system and process.

[0037] A typical embodiment of the present invention provides a two-stage ozone biological fluidized bed water purification system, which is installed at the front end of a conventional water purification system to pretreat raw water; the system includes a primary ozone oxidation tank, a primary biological fluidized bed, a secondary ozone oxidation tank, and a secondary biological fluidized bed in sequence according to the flow direction of the raw water. The primary ozone oxidation tank includes an outer tank and an inner tank. The outer tank is enclosed and has an inlet and an outlet at its upper part. The inlet is connected to the inner tank via a pipe. A sludge collection area is set at the bottom of the outer tank. The inner tank is a cylindrical structure with open upper and lower ends and is suspended inside the outer tank. The top of the inner tank is higher than the water surface of the primary ozone oxidation tank. The channel between the side walls of the outer tank and the inner tank is set as a sedimentation area with a sedimentation structure. The inner tank is an ozone oxidation zone. A first ozone aeration device is set at the lower part of the ozone oxidation zone. The flow direction of the raw water in the primary ozone oxidation tank is ozone oxidation zone, sedimentation zone, and outlet in sequence. Both the primary and secondary biological fluidized beds are enclosed structures, and each contains a fluidized layer filled with packing material and activated carbon. The secondary ozone oxidation tank is also enclosed and contains a second ozone aeration device and a hydrogen peroxide dosing device. The first and second ozone aeration devices are connected to an ozone source, and the hydrogen peroxide dosing device is connected to a hydrogen peroxide source.

[0038] In some embodiments, an ozone exhaust gas destroyer is installed at the top of the primary ozone oxidation tank. In some embodiments, the precipitation structure is an inclined plate and / or an inclined tube.

[0039] In some embodiments, the first ozone aeration device is an aeration titanium disc.

[0040] In one specific embodiment, the primary ozone oxidation tank is a square or circular tank with a sealed top, equipped with an ozone tail gas destroyer, and includes an ozone reaction zone, a sedimentation zone, and a sludge collection zone. The ozone reaction zone is a square or circular tank located in the middle of the primary ozone oxidation tank, with its top 0.5m to 0.8m above the water surface. The height of the reaction zone is 2 / 3 to 3 / 4 of the height of the primary ozone oxidation tank, and it is 1.5 to 2.0m from the top of the bottom sludge collection zone. A first ozone aeration device, which can be an aeration titanium disc, is installed inside the reaction zone, 0.5 to 1.0m from the bottom. The first ozone aeration device is connected to an ozone generator via pipes and valves. Source water enters the upper part of the intermediate ozone reaction zone through pipes. Between the ozone reaction zone and the primary ozone oxidation tank is a sedimentation zone, using inclined plate / inclined tube sedimentation. Inclined plates / inclined tubes are installed in the upper part of the sedimentation zone, with a 1.0 to 2.0m clear water zone above the inclined plates / inclined tubes. The length of the inclined plates is 0.8-1.2m. The inclined plates are spaced 50-80 mm apart, with an inclination angle of 45°-60°. The lower part of the ozone reaction zone is the sludge collection area, which is an inverted conical sludge hopper with a slope of 45%~60°. The bottom of the sludge hopper is connected to a sludge discharge pipe and valves. The effective depth of the primary ozone oxidation tank is no less than 9.0 m, and the outlet is located at the upper part of the primary ozone oxidation tank.

[0041] In some embodiments, the primary biological fluidized bed is a closed tank structure with an inlet at the bottom and an outlet at the top.

[0042] In some embodiments, the primary biological fluidized bed consists of a uniform water distribution zone, a support layer, and a fluidization layer from bottom to top.

[0043] In some embodiments, an ozone exhaust gas destroyer is installed at the top of the primary biological fluidized bed.

[0044] In one specific embodiment, the primary biological fluidized bed is a square or circular pool with a sealed top and an ozone exhaust gas destroyer. It has an inlet at the bottom and an outlet at the top. Internally, from bottom to top, it consists of a uniform water distribution zone, a support layer, and a fluidized layer. The support layer can be made of 3 to 4 layers of graded pebbles. The fluidized layer filler is made of high-hardness, wear-resistant, lightweight filler, such as coal-based or coconut shell activated carbon. The fluidized layer height is 1.5~2.0m, and the particle size of the biological fluidized bed filler is 0.5-1.0 mm.

[0045] The effluent from the primary ozone oxidation tank can either enter the primary biological fluidized bed by gravity or be pressurized by a water pump.

[0046] In some embodiments, the activated carbon filled in the primary biological fluidized bed is coal-based activated carbon, and the activated carbon filled in the secondary biological fluidized bed is coconut shell activated carbon.

[0047] In some embodiments, the secondary ozone oxidation tank has an inlet at the top and an outlet at the bottom.

[0048] In some embodiments, an ozone exhaust gas destroyer is installed at the top of the secondary ozone oxidation tank. In some embodiments, the second ozone aeration device may be an aeration titanium disc, a jet aerator, or a self-excited pulse cavitation jet.

[0049] In one specific embodiment, the secondary ozone oxidation tank is a square or circular tank with a sealed top and an ozone exhaust gas destroyer. It has an inlet at the top and an outlet at the bottom. A second ozone aeration device is installed inside, 0.5 to 1.0 m from the bottom. The second ozone aeration device can be an aeration titanium disc, a jet aerator, or a self-excited pulse cavitation jet, and a hydrogen peroxide dosing device is installed inside.

[0050] In some embodiments, the secondary biological fluidized bed is a closed tank structure with an inlet at the bottom and an outlet at the top.

[0051] In some embodiments, the secondary biological fluidized bed consists of a uniform water distribution zone, a support layer, and a fluidization layer from bottom to top.

[0052] In some embodiments, an ozone exhaust gas destroyer is installed at the top of the secondary biological fluidized bed.

[0053] In one specific embodiment, the secondary biological fluidized bed is a square or circular pool with a sealed top and an ozone exhaust gas destroyer. It has an inlet at the bottom and an outlet at the top. Internally, from bottom to top, it consists of a uniform water distribution zone, a support layer, and a fluidized layer. The support layer can be made of 3 to 4 layers of graded pebbles. The fluidized layer filler is made of high-hardness, wear-resistant, lightweight filler, such as coal-based or coconut shell activated carbon. The fluidized layer height is 1.5~2.0m, and the particle size of the biological fluidized bed filler is 0.5~1.0 mm.

[0054] The effluent from the secondary ozone oxidation tank can either enter the secondary biological fluidized bed by gravity or be pressurized by a water pump.

[0055] The effective water depth of the primary ozone oxidation pond, the secondary ozone oxidation pond, the primary biological fluidized bed, and the secondary biological fluidized bed shall not be less than 9.0m.

[0056] The ozone source can be an ozone generating system. The ozone generating system, ozone aeration device, pipelines, valves, flow meters, etc. constitute an ozone dosing system.

[0057] The hydrogen peroxide source can be a hydrogen peroxide storage tank. The hydrogen peroxide storage tank, metering pump, pipelines, valves, flow meters, etc. constitute a hydrogen peroxide dosing system.

[0058] On the other hand, a two-stage ozone biological fluidized bed water purification process provides the above-mentioned two-stage ozone biological fluidized bed water purification system, in which raw water is sequentially fed into a primary ozone oxidation tank, a primary biological fluidized bed, a secondary ozone oxidation tank, and a secondary biological fluidized bed for treatment.

[0059] In some embodiments, the ozone dosage in the primary ozone oxidation tank is 0.5~2 mg / L; the hydraulic retention time in the ozone oxidation zone is 5~20 min.

[0060] In some embodiments, the contact time between the fluidized bed and water in the primary biological fluidized bed is 5 to 30 minutes.

[0061] In some embodiments, the ozone dosage in the secondary ozone oxidation tank is 2-5 mg / L, the hydrogen peroxide dosage is 0-2 mg / L, and the hydraulic retention time is 5-20 min. The hydrogen peroxide dosage is not zero in any of these embodiments.

[0062] In some embodiments, the contact time between the fluidized bed and water in the secondary biological fluidized bed is 5 to 30 minutes.

[0063] In some embodiments, the ratio of ozone dosage in the primary ozone oxidation tank to ozone dosage in the secondary ozone oxidation tank is 1:3 to 8.

[0064] Thirdly, the application of the above-mentioned two-stage ozone biological fluidized bed water purification system or two-stage ozone biological fluidized bed water purification process in treating slightly polluted water sources into drinking water.

[0065] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0066] Example A two-stage ozone biological fluidized bed water treatment system, such as Figure 1 As shown, it includes a reaction system, an ozone dosing system 13, and a hydrogen peroxide dosing system 11. The reaction system consists of a primary ozone reaction tank, a primary biological fluidized bed 8, a secondary ozone reaction tank 9, and a secondary biological fluidized bed 10 connected in sequence. The water depth of each ozone reaction tank is not less than 9.0m.

[0067] The primary ozone oxidation tank has an inlet 1 on its upper sidewall, and a sealed top. It is equipped with an ozone exhaust gas disruptor 6 and a breathing valve (for balancing internal and external air pressure). The primary ozone oxidation tank contains an ozone reaction zone 2, a sedimentation zone 3, and a sludge collection zone 5. The sedimentation zone 3 is located between the sidewall of the ozone reaction zone 2 and the sidewall of the primary ozone oxidation tank. The ozone reaction zone 2 contains a first ozone aeration device 4 connected to the ozone dosing system 13. It uses a top-inlet, bottom-outlet design, with an ozone dosage of 0.5 mg / L and an ozone-water contact time of 15 min. The effluent enters the inclined plate sedimentation device in the sedimentation zone 3 from the bottom outlet. The inclined plate sedimentation device has an inclined plate length of 0.8 m, an inclined plate spacing of 50 mm, an inclination angle of 60°, and a clear water zone protection height of 1.0 m. Water is pumped from the top outlet of the inclined plate sedimentation device into the primary biological fluidized bed via a booster pump 7, with a residence time of 20 min.

[0068] The primary biological fluidized bed is sealed at the top and equipped with an ozone tail gas destroyer. It adopts a bottom water inlet and top water outlet. The interior consists of a uniform water distribution zone, a support layer, and a fluidized bed from bottom to top. The support layer can be made of three layers of graded pebbles, which are filled with coal-based activated carbon with a particle size of 0.4-0.6 mm, a filling thickness of 1.5 m, an expansion rate of 45%, and a contact time with water of 10 min. The effluent enters the secondary ozone reaction tank.

[0069] The secondary ozone reactor 9 is sealed at the top and equipped with an ozone exhaust gas destroyer and a breathing valve (for balancing internal and external air pressure). It adopts a top-inlet and bottom-outlet design. A second ozone aeration device 12 is installed inside, which is connected to an ozone dosing system 13. The ozone dosage is 4 mg / L. The hydrogen peroxide dosing system 11 adds hydrogen peroxide to the secondary ozone reactor 9 at a dosage of 2 mg / L. The contact time between ozone / hydrogen peroxide and water is 15 min. The effluent enters the secondary biological fluidized bed inlet system from the bottom outlet through a booster pump.

[0070] The secondary biological fluidized bed 10 is sealed at the top and equipped with an ozone exhaust gas destroyer. It adopts a bottom water inlet and top water outlet. The interior consists of a uniform water distribution zone, a support layer, and a fluidized bed from bottom to top. The support layer can be made of 4 layers of graded pebbles, which are filled with coconut shell activated carbon with a particle size of 0.4-0.6 mm, a filling thickness of 1.5 m, an expansion rate of 45%, and a water contact time of 10 min.

[0071] The water from a Yellow River source reservoir (permanganate index: 7.31 mg / L, ammonia nitrogen: 0.98 mg / L, 2-MIB: 360.5 ng / L, GSM: 36.4 ng / L, SS: 24 mg / L) was treated using the above system. Testing showed that the average permanganate index of the effluent was 0.37 mg / L, the ammonia nitrogen was less than 0.02 mg / L, the 2-MIB concentration was below the detection limit (<2.2 ng / L), the GSM concentration was below the detection limit (<3.8 ng / L), and bromate was not detected.

[0072] Comparative Example 1 Water from a Yellow River source reservoir (permanganate index: 7.31 mg / L, ammonia nitrogen: 0.98 mg / L, 2-MIB: 360.5 ng / L, GSM: 36.4 ng / L, SS: 24 mg / L) was treated using an existing single-stage ozone-hydrogen peroxide advanced oxidation biological fluidized bed system (i.e., Example 1 omits the first-stage ozone reactor and the first-stage biological fluidized bed). The ozone dosage was 6.0 mg / L and the hydrogen peroxide dosage was 2 mg / L. The effluent permanganate index averaged 1.32 mg / L, ammonia nitrogen was less than 0.18 mg / L, 2-MIB concentration was 9.2 ng / L, GSM concentration was below the detection limit (<3.8 ng / L), and bromate was not detected.

[0073] Comparative Example 2 Water from a Yellow River source reservoir (permanganate index: 7.31 mg / L, ammonia nitrogen: 0.98 mg / L, 2-MIB: 360.5 ng / L, GSM: 36.4 ng / L, SS: 24 mg / L) was treated using a system consisting of two existing single-stage ozone-hydrogen peroxide advanced oxidation biological fluidized bed systems connected in series (i.e., in Example 1, the structure of the primary ozone reactor adopts the structure of the secondary ozone reactor, and the structure of the primary biological fluidized bed is the same as that of the secondary biological fluidized bed). The primary ozone dosage was 2 mg / L, the primary hydrogen peroxide dosage was 1 mg / L, the secondary ozone dosage was 4 mg / L, and the secondary hydrogen peroxide dosage was 1 mg / L. Testing showed that the effluent permanganate index averaged 0.73 mg / L, ammonia nitrogen was less than 0.02 mg / L, 2-MIB concentration was 5.1 ng / L, GSM concentration was below the detection limit (<3.8 ng / L), and bromate was not detected.

[0074] By comparing the effluent sampling and testing results of the embodiments and comparative examples 1-2, it can be found that the two-stage ozone biological fluidized bed water purification system and process of the present invention can effectively remove refractory organic matter, ammonia nitrogen, 2MIB, and GSM from the water, and bromate does not exceed the standard; at the same time, the ozone dosage is reduced (reduced by 25%), the treatment effect is stable and the operating cost is low.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-stage ozone biological fluidized bed water purification system, characterized in that it is used for... It is installed at the front end of a conventional water purification system to pre-treat raw water; in the order of raw water flow, it includes a primary ozone oxidation tank, a primary biological fluidized bed, a secondary ozone oxidation tank, and a secondary biological fluidized bed. The primary ozone oxidation tank includes an outer tank and an inner tank. The outer tank is enclosed and has an inlet and an outlet at its upper part. The inlet is connected to the inner tank via a pipe. A sludge collection area is set at the bottom of the outer tank. The inner tank is a cylindrical structure with open upper and lower ends and is suspended inside the outer tank. The top of the inner tank is higher than the water surface of the primary ozone oxidation tank. The channel between the side walls of the outer tank and the inner tank is set as a sedimentation area with a sedimentation structure. The inner tank is an ozone oxidation zone. A first ozone aeration device is set at the lower part of the ozone oxidation zone. The flow direction of the raw water in the primary ozone oxidation tank is ozone oxidation zone, sedimentation zone, and outlet in sequence. Both the primary and secondary biological fluidized beds are enclosed structures, and each contains a fluidized layer filled with packing material and activated carbon. The secondary ozone oxidation tank is also enclosed and contains a second ozone aeration device and a hydrogen peroxide dosing device. The first and second ozone aeration devices are connected to an ozone source, and the hydrogen peroxide dosing device is connected to a hydrogen peroxide source. The primary biological fluidized bed is a closed tank structure with an inlet at the bottom and an outlet at the top. Alternatively, the primary biological fluidized bed consists of a uniform water distribution zone, a support layer, and a fluidized layer from bottom to top; Alternatively, an ozone exhaust gas destroyer may be installed at the top of the primary biological fluidized bed; The secondary biological fluidized bed is a closed tank structure with an inlet at the bottom and an outlet at the top; Alternatively, the secondary biological fluidized bed consists of a uniform water distribution zone, a support layer, and a fluidized layer from bottom to top; Alternatively, an ozone exhaust gas destroyer may be installed at the top of the secondary biological fluidized bed; The fluidized bed is filled with porous packing material; The activated carbon filled in the primary biological fluidized bed is coal-based activated carbon, while the activated carbon filled in the secondary biological fluidized bed is coconut shell activated carbon. The second ozone aeration device can be an aeration titanium disc, a jet aerator or a self-excited pulse cavitation jet. The dual-stage ozone biological fluidized bed water purification system integrates ozone oxidation, advanced ozone oxidation, ozone catalytic oxidation, cavitation, and biological oxidation.

2. The two-stage ozone biological fluidized bed water purification system as described in claim 1, characterized in that, The precipitation structure is an inclined plate and / or an inclined tube; Alternatively, the first ozone aeration device is an aeration titanium disc; Alternatively, an ozone exhaust gas destroyer may be installed at the top of the primary ozone oxidation tank.

3. The two-stage ozone biological fluidized bed water purification system as described in claim 1, characterized in that, In the secondary ozone oxidation tank, an inlet is set at the top and an outlet is set at the bottom; Alternatively, an ozone exhaust gas destroyer may be installed at the top of the secondary ozone oxidation tank.

4. A two-stage ozone biological fluidized bed water purification process, characterized in that, A two-stage ozone biological fluidized bed water purification system according to any one of claims 1 to 3 is provided, wherein raw water is sequentially fed into a primary ozone oxidation tank, a primary biological fluidized bed, a secondary ozone oxidation tank, and a secondary biological fluidized bed for treatment.

5. The two-stage ozone biological fluidized bed water purification process as described in claim 4, characterized in that, The ozone dosage in the primary ozone oxidation tank is 0.5~2mg / L, and the hydraulic retention time in the ozone oxidation zone is 5~20min; Alternatively, in a primary biological fluidized bed, the contact time between the fluidized layer and water is 5 to 30 minutes. Alternatively, the ozone dosage in the secondary ozone oxidation tank is 2-5 mg / L, the hydrogen peroxide dosage is 0-2 mg / L, and the hydraulic retention time is 5-20 min, wherein the hydrogen peroxide dosage is not 0. Alternatively, in a secondary biological fluidized bed, the contact time between the fluidized layer and water is 5 to 30 minutes.

6. The two-stage ozone biological fluidized bed water purification process as described in claim 4, characterized in that, The ratio of ozone dosage in the primary ozone oxidation tank to that in the secondary ozone oxidation tank is 1:3~8.

7. The application of the two-stage ozone biological fluidized bed water purification system according to any one of claims 1 to 3 or the two-stage ozone biological fluidized bed water purification process according to any one of claims 4 to 6 in treating slightly polluted water sources into drinking water.

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