A circulating biofilter based on encapsulated nitrifying bacteria and a method for operating the same

Abstract

The application provides a circulating biological filter based on encapsulated nitrifying bacteria and a running method thereof, which comprises a conical bottom area V1, a cylindrical reaction area V2 and a three-phase separation area V3, the bottom of the three-phase separation area V3 is communicated with the cylindrical reaction area V2, the bottom of the cylindrical reaction area V2 is communicated with the conical bottom area V1, the conical bottom area V1 is formed by a conical bottom inner cavity, the cylindrical reaction area V2 is formed by a reaction area inner cavity, and the three-phase separation area V3 is formed by an overflow weir inner cavity. The application optimizes the proportion of each part of the three-phase biological fluidized bed biological filter, reduces the height-diameter ratio, sets a flow guide cylinder and a flow guide cover, and uses air to push, so that the good environment required by nitrifying bacteria can be ensured, the filler can be fully fluidized, the mass transfer effect is enhanced, and the ammonia nitrogen pollutants in the aquaculture tail water have good treatment effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aquaculture tail water treatment, and particularly relates to a circulating biofilter based on encapsulated nitrifying bacteria and a running method thereof. BACKGROUND

[0002] In recent years, the aquaculture industry has shown strong development momentum, and the farming mode has undergone significant changes, gradually changing from traditional low-density and extensive to modern high-density and intensive. With the continuous improvement and innovation of aquaculture technology, the efficiency of aquaculture is improved, and the cost is reduced, which promotes the development of its scale and industrialization, but at the same time, it also brings a large amount of aquaculture tail water discharge and treatment problems. The aquaculture tail water treatment technology in China is still in its infancy, and compared with the demand of the industry development, it is relatively lagging behind. This situation makes the aquaculture concentrated area face the serious situation of continuous deterioration of water quality, which poses a threat to the stability of the ecological system and the sustainable development of the fishery industry that cannot be ignored.

[0003] At present, aquaculture tail water treatment mainly removes solid particles, nutrients and other substances in the tail water through physical filtration and the use of filter-feeding animals, aquatic plants, algae and microorganisms. For example, fish-shellfish-algae mixed culture, or discharging or recycling after purifying the aquaculture tail water in an ecological pond. However, ecological purification generally requires a large area, which will occupy a certain amount of aquaculture area, and it is difficult to implement and promote in areas where land is scarce. In addition, in ecological purification, it often takes 2-3 growth cycles to achieve the optimal efficiency of plant purification, which is easily affected by diseases and pests, and there are also problems such as plant death and wintering, and threshold value for the absorption of dissolved pollutants, resulting in unstable treatment efficiency.

[0004] In the design of a factory-like recirculating aquaculture system, the water treatment area generally accounts for 25%-30% of the aquaculture area. In order to achieve timely removal of particles, the daily circulation frequency of the recirculating aquaculture system can reach more than 20 times, resulting in a short hydraulic retention time of the biofilter in the water treatment system, mostly less than 1h. In the treatment of pond aquaculture tail water, in order to protect the aquaculture area, when using biological filtration equipment to treat dissolved pollutants, the biological filtration equipment occupies a small area and has a limited volume, and the hydraulic retention time is also short, resulting in low water treatment efficiency. Generally, the HRT of a traditional sewage treatment reactor is between 1h and 5h. In the treatment of aquaculture tail water, there is a problem of mutual contradiction between the treatment area and the hydraulic retention time. In addition, due to the low concentration of pollutants in the aquaculture water, the types and quantity of denitrifying microorganisms are small, and they are usually at a disadvantage in interspecific competition, especially in the early stage of aquaculture. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a circulating biofilter based on encapsulated nitrifying bacteria and a running method thereof, to solve the problem of mutual contradiction between the treatment area and the hydraulic retention time in the treatment of aquaculture tail water in the prior art.

[0006] A circulating biofilter based on encapsulated nitrifying bacteria and its operating method, comprising a conical bottom region V1, a cylindrical reaction zone V2 and a three-phase separation zone V3, the bottom of the three-phase separation zone V3 being in communication with the cylindrical reaction zone V2, the bottom of the cylindrical reaction zone V2 being in communication with the conical bottom region V1, the conical bottom region V1 being formed by a conical bottom inner cavity, the cylindrical reaction zone V2 being formed by a reaction zone inner cavity, and the three-phase separation zone V3 being formed by an overflow weir inner cavity.

[0007] The conical bottom is in communication with a water inlet bucket through a water inlet pipe, a water pump for controlling water inflow being installed in the middle of the water inlet pipe, the bottom of the conical bottom being in communication with an air inlet pipe, the other end of the air inlet pipe being connected to an oxygenator for aeration, a flowmeter for controlling air inflow being connected to the middle of the air inlet pipe, and a gas distribution plate being arranged at the bottom of the conical bottom.

[0008] A detachable flow guide cylinder is arranged at the center of the reaction zone inner cavity, a flow guide cover being arranged above the flow guide cylinder, the inner diameter of the flow guide cover being larger than the outer diameter of the flow guide cylinder, and the upper end of the flow guide cover being open.

[0009] An overflow weir is installed at the top of the reaction zone through a flow guide cylinder fixing ring, a water collecting cover being arranged around the overflow weir, the water collecting cover being in communication with a water outlet pipe, the water outlet pipe being connected to the water inlet bucket, a valve being installed on the water outlet pipe, and an agitator being arranged in the water inlet bucket.

[0010] Preferably, the volume ratio of the conical bottom region V1, the cylindrical reaction zone V2 and the three-phase separation zone V3 is V2=1.6V3=7V1.

[0011] Preferably, the overflow weir is serrated at the water outlet.

[0012] Preferably, in the three-phase biofluidized bed biofilter, the diameter of the gas distribution plate is the same as the diameter of the bottom of the conical bottom, and the diameter of the gas hole is 0.1-0.6mm.

[0013] Preferably, in the three-phase biofluidized bed biofilter, the bottom of the flow guide cover is horn-shaped and forms a 45° angle with the horizontal plane, and the conical bottom forms a 60° angle with the horizontal plane.

[0014] Preferably, in the three-phase biofluidized bed biofilter, the flow guide cylinder is detachable and is fixed through a pair of upper and lower fixing rings.

[0015] Preferably, in the three-phase biofluidized bed biofilter, the flow guide cover is detachable and is connected to the water collecting cover through a fixing plate.

[0016] Preferably, the water inlet pipe and the valve are arranged above the fixing ring, and the water outlet pipe and the valve are arranged at the bottom of the water collecting cover.

[0017] Preferably, the biological filter adopts nitrifying bacteria filler, and a preparation method of the nitrifying bacteria filler is as follows: centrifuging nitrifying activated sludge enriched in culture, dewatering by pressure filtration to a water content of 70%-80%; using a polypropylene, nylon porous film with a pore size of 200-500 nm, heat sealing at 150-180 DEG C to form a 3*3*0.3 cm thin sheet type packaging nitrifying bacteria filler, and the nitrifying activated sludge mass per unit area is about 0.02-0.05 g / cm 2 .

[0018] 10. A running method of a circulating biological filter based on packaging nitrifying bacteria, comprising the following steps:

[0019] The first step is to put the nitrifying bacteria filler into the three-phase biological fluidized bed biological filter to carry out filler domestication.

[0020] The second step is to maintain the ammonia nitrogen concentration of influent water at 5-15.0 mg / L, the pH value at 7.5-8.0, and the dissolved oxygen at about 4 mg / L during domestication, and to replace water every 24 h until domestication matures.

[0021] The third step is to connect the reactor influent pipe and the effluent pipe to the influent bucket, control the influent flow by a water pump, control the air flow by a flow meter, and start the circulating operation to degrade ammonia nitrogen.

[0022] The fourth step is to completely remove low-concentration ammonia nitrogen wastewater.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] 1. The present application optimizes the proportion of each part of the three-phase biological fluidized bed biological filter, reduces the height-diameter ratio, and sets a flow guide cylinder and a flow guide cover, so that the nitrifying bacteria can be provided with a good environment, the filler can be fully fluidized, the mass transfer effect is enhanced, and the ammonia nitrogen pollutants in aquaculture tail water can be well treated.

[0025] 2. The present application provides a large number of high-activity bacteria in a short time by packaging nitrifying bacteria, has the advantages of maintaining high-efficiency biological concentration, low sludge yield, strong resistance to toxic substances, etc. The reactor start-up time can be shortened, the filler filling rate can be reduced, and a sludge-water separation device is not needed.

[0026] 3. The present application circulates the three-phase biological fluidized bed biological filter, has high biological concentration, short residence time, and high mass transfer efficiency. When the influent ammonia nitrogen is 2-10 mg / L and the hydraulic retention time is 15-30 min, ammonia nitrogen and nitrite and other harmful substances can be completely removed within 24 h.

[0027] 4. This invention utilizes encapsulated nitrifying bacteria to increase reactor biomass. Under a high-speed fluidized bed and circulating operation mode involving gas, liquid, and solid phases, it achieves highly efficient removal of ammonia nitrogen from aquaculture wastewater within an extremely short hydraulic retention time. This reduces the footprint of water treatment facilities, improves water treatment efficiency, and lowers infrastructure costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the main structure of the present invention;

[0029] Figure 2 This is a scanning electron microscope image of the porous thin film surface of the present invention;

[0030] Figure 3 This is a schematic diagram of ammonia nitrogen in the effluent during the acclimatization period of this invention;

[0031] Figure 4 This is a schematic diagram of nitrite concentration during the domestication period of this invention;

[0032] Figure 5 This is a schematic diagram of the ammonia nitrogen removal rate curve of the present invention.

[0033] In the diagram: 1. Serrated overflow weir, 2. Water collection hood, 3. Three-phase separation guide hood, 4. Guide tube fixing ring, 5. Detachable guide tube, 6. Reaction zone, 7. Water outlet pipe, 8. Water inlet pipe, 9. Conical bottom, 10. Air inlet pipe, 11. Air distribution plate, 12. Water inlet tank, 13. Agitator, 14. Water pump, 15. Flow meter, 16. Aerator, 17. Valve, 18. Fixing plate. Detailed Implementation

[0034] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0035] like Figure 1 As shown, the present invention provides a circulating biofilter based on encapsulated nitrifying bacteria and its operation method, including a conical bottom region V1, a cylindrical reaction zone V2 and a three-phase separation zone V3. The bottom of the three-phase separation zone V3 is connected to the cylindrical reaction zone V2, and the bottom of the cylindrical reaction zone V2 is connected to the conical bottom region V1. The conical bottom region V1 is formed by the inner cavity of the conical bottom 9. The volume ratio of the conical bottom region V1, the cylindrical reaction zone V2 and the three-phase separation zone V3 is V2 = 1.6V3 = 7V1. The cylindrical reaction zone V2 is formed by the inner cavity of the reaction zone 6, and the three-phase separation zone V3 is formed by the inner cavity of the overflow weir 1. The outlet of the overflow weir 1 is serrated.

[0036] The conical bottom 9 is communicated with the water inlet barrel 12 through the water inlet pipe 8, the water pump 14 for controlling the water inlet flow is arranged in the middle of the water inlet pipe 8, and the water inlet pipe 8 and the valve 17 are arranged above the fixed ring 4; the water outlet pipe 7 and the valve 17 are arranged at the bottom of the water collecting cover 2, the bottom of the conical bottom 9 is communicated with the air inlet pipe 10, the other end of the air inlet pipe 10 is connected with the oxygenation machine 16 for aeration, the flowmeter 15 for controlling the air inlet flow is arranged in the middle of the air inlet pipe 10, the bottom of the conical bottom 9 is provided with the air distribution plate 11, the diameter of the air distribution plate 11 in the biological filter is the same as the diameter of the bottom of the conical bottom 9, and the air hole diameter is 0.1-0.6 mm;

[0037] The detachable flow guide cylinder 5 is arranged in the center of the inner cavity of the reaction zone 6, the flow guide cylinder 5 is detachable and is fixed through the upper and lower pair of fixed rings 4, the flow guide cover 3 is arranged above the flow guide cylinder 5, the inner diameter of the flow guide cover 3 is greater than the outer diameter of the flow guide cylinder 5, the upper end of the flow guide cover 3 is arranged in an open manner, the trumpet-shaped opening at the bottom of the flow guide cover 3 is at an inclined angle of 45° with the horizontal plane, the flow guide cover 3 is detachable and is connected with the water collecting cover 2 through the fixed plate 18; the conical bottom 9 is at an inclined angle of 60° with the horizontal plane.

[0038] The overflow weir 1 is arranged at the top of the reaction zone 6 through the flow guide cylinder fixed ring 4, the overflow weir 1 is provided with the water collecting cover 2 around, the water collecting cover 2 is communicated with the water outlet pipe 7, the water outlet pipe 7 is communicated to the water inlet barrel 12, the valve 17 is arranged on the water outlet pipe 7, and the water inlet barrel 12 is provided with the stirrer 13.

[0039] Reference Figure 2 Firstly, the nitration active sludge enriched and cultured is centrifuged, pressure-filtered and dewatered to have a water content of 70%-80%; the polypropylene and nylon porous film with a pore diameter of 200-500 nm is used to heat seal and form a 3*3*0.3 cm thin sheet type packaging nitration bacteria filler at 150-180 ℃, and the unit area contains nitration active sludge with a mass of about 0.02-0.05 g / cm2;

[0040] Reference Figure 3 The ammonia nitrogen concentration of the water inlet is 2-10.0 mg / L, the pH value is 7.5-8.0, the filling rate of the sheet type packaging nitration bacteria filler in the reactor is 10%, the biomass is about 5000 mg / L, and the hydraulic retention time is 15-30 min. The water inlet is pumped into the reactor by the water pump, the air blowing aeration is used for the aeration in the reactor, the sheet type packaging nitration bacteria filler is maintained in high-speed fluidization, the air-water ratio is 10-15, the dissolved oxygen is about 4-8.0 mg / L, after the high-speed fluidization reaction of the gas-liquid-solid three phases, the water outlet returns to the water inlet barrel, and the water inlet barrel is recycled multiple times to enter the reactor for the nitration reaction. The ammonia nitrogen removal rate can be more than 95% within 12-24 h.

[0041] Reference Figure 4, according to the filling rate is 10% into the three-phase biological fluidized bed biological filter to carry out filler acclimation, acclimation period maintain influent ammonia nitrogen concentration of 5-15.0mg / L, pH value is 7.5-8.0, dissolved oxygen is about 4mg / L, 24h water change. The damage of encapsulation method to nitrifying bacteria is small, and the activity recovers quickly. When the influent ammonia nitrogen is 10mg / L, the removal rate reaches more than 95% in the first day; when the influent ammonia nitrogen is 5mg / L, it takes two days; when the influent ammonia nitrogen is 15mg / L, it takes three days. The nitrite salt is maintained at a low concentration range of 0-0.12mg / L, and the concentration is basically maintained at 0.01mg / L after the 7th day.

[0042] When acclimation matures, the reactor influent pipe 8 and effluent pipe 7 are connected to the influent tank 12, the volume of the influent tank is 4-8 times the volume of the reactor, the influent ammonia nitrogen concentration is 2-10mg / L, the water flow is controlled by the water pump 14, the hydraulic retention time is 15-30min, the pH value is 7.5-8.0, the air flow is controlled by the flow meter 15, the gas-water ratio is 10, the dissolved oxygen is about 8.0mg / L, the circulation operation is started to degrade ammonia nitrogen;

[0043] Reference Figure 5 According to the ammonia nitrogen degradation rate curve, the three-phase biological fluidized bed biological filter shows good removal efficiency for low-concentration ammonia nitrogen wastewater. When the influent ammonia nitrogen concentration is 2-5mg / L and the hydraulic retention time is 15min, the ammonia nitrogen can be completely removed within 12h. When the influent ammonia nitrogen concentration is 10mg / L and the hydraulic retention time is 30min, the ammonia nitrogen can be completely removed within 18h. The effluent nitrite salt is maintained at 0-1.0mg / L.

[0044] The embodiments of the present application are given for example and description, although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for operating a circulating biofilter based on encapsulated nitrifying bacteria, wherein the circulating biofilter based on encapsulated nitrifying bacteria comprises a conical bottom region V1, a cylindrical reaction zone V2, and a three-phase separation zone V3, characterized in that: The bottom of the three-phase separation zone V3 is connected to the cylindrical reaction zone V2, and the bottom of the cylindrical reaction zone V2 is connected to the conical bottom region V1. The conical bottom region V1 is formed by the inner cavity of the conical bottom (9), the cylindrical reaction zone V2 is formed by the inner cavity of the reaction zone (6), and the three-phase separation zone V3 is formed by the inner cavity of the overflow weir (1). The conical bottom (9) is connected to the water inlet tank (12) through the water inlet pipe (8). A water pump (14) for controlling the water inlet flow is installed in the middle of the water inlet pipe (8). The bottom of the conical bottom (9) is connected to the air inlet pipe (10). The other end of the air inlet pipe (10) is connected to the aerator (16) for aeration. A flow meter (15) for controlling the air intake is connected in the middle of the air inlet pipe (10). An air distribution plate (11) is provided at the bottom of the conical bottom (9). A detachable guide tube (5) is provided in the center of the inner cavity of the reaction zone (6). A guide shroud (3) is provided above the guide tube (5). The inner diameter of the guide shroud (3) is larger than the outer diameter of the guide tube (5). The upper end of the guide shroud (3) is open. An overflow weir (1) is installed on the top of the reaction zone (6) via a guide tube fixing ring (4). A water collection hood (2) is provided around the overflow weir (1). The water collection hood (2) is connected to a water outlet pipe (7). The water outlet pipe (7) is connected to a water inlet tank (12). A valve (17) is installed on the water outlet pipe (7). A stirrer (13) is provided inside the water inlet tank (12). The volume ratio of the conical bottom region V1, the cylindrical reaction region V2, and the three-phase separation region V3 is V2=1.6V3=7V1; The circulating biological filter uses nitrifying bacteria packing material. The preparation method of the nitrifying bacteria packing material involves centrifuging and dewatering enriched nitrifying activated sludge to a moisture content of 70%-80% via filtration. Then, using a porous polypropylene or nylon membrane with a pore size of 200-500 nm, the material is heat-sealed at 150-180℃ to form a 3*3*0.3 cm sheet-like encapsulated nitrifying bacteria packing material, with a nitrifying activated sludge mass content of 0.02-0.05 g / cm³ per unit area. 2 ; The operation method of this circulating biofilter based on encapsulated nitrifying bacteria includes the following steps: Step 1: Introduce nitrifying bacteria packing material into the circulating biological filter to acclimate the packing material; Step 2: During the acclimatization period, maintain the influent ammonia nitrogen concentration at 5-15.0 mg / L, pH at 7.5-8.0, and dissolved oxygen at 4 mg / L, and change the water every 24 hours until the acclimatization is complete; Step 3: Connect the reactor inlet pipe (8) and outlet pipe (7) to the inlet tank (12). The ammonia nitrogen concentration in the inlet water is 2-10 mg / L. Control the inlet water flow rate through the water pump (14) to make the hydraulic residence time 15-30 min and the pH value 7.5-8.

0. Control the air intake through the flow meter (15) to control the air-to-water ratio to 10 and the dissolved oxygen to 8.0 mg / L. Start the circulation operation to degrade ammonia nitrogen. Step 4: Continue until the low concentration of ammonia nitrogen in the wastewater is completely removed.

2. The operation method of the circulating biofilter based on encapsulated nitrifying bacteria as described in claim 1, characterized in that: The overflow weir (1) has a sawtooth-shaped outlet.

3. The operation method of the circulating biofilter based on encapsulated nitrifying bacteria as described in claim 1, characterized in that: The diameter of the air distribution plate (11) in the circulating biofilter is the same as the bottom diameter of the conical bottom (9), and the diameter of the air holes is 0.1-0.6 mm.

4. The operation method of the circulating biofilter based on encapsulated nitrifying bacteria as described in claim 1, characterized in that: The bottom of the shroud (3) has a flared opening at a 45° angle to the horizontal plane; the conical bottom (9) has a 60° angle to the horizontal plane.

5. The operation method of the circulating biofilter based on encapsulated nitrifying bacteria as described in claim 1, characterized in that: The guide tube (5) is detachable and is fixed by a pair of upper and lower fixing rings (4).

6. The operation method of the circulating biofilter based on encapsulated nitrifying bacteria as described in claim 1, characterized in that: The flow guide (3) is detachable and is connected to the water collection cover (2) via a fixing plate (18).

7. The operating method of the circulating biofilter based on encapsulated nitrifying bacteria as described in claim 1, characterized in that: The inlet pipe (8) is positioned above the fixing ring (4); the outlet pipe (7) and valve (17) are positioned at the bottom of the water collection cover (2).

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