Circulating biological filter based on packaged nitrifying bacteria and operation method of circulating biological filter

Abstract

The invention provides a circulating biological filter based on packaged nitrifying bacteria and an operation method thereof.The circulating biological filter 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, and the conical bottom area V1 is communicated with the cylindrical reaction area V2. The three-phase separation area V3 is formed by a conical bottom inner cavity, the cylindrical reaction area V2 is formed by a reaction area inner cavity, and the conical bottom area V1 is formed by an overflow weir inner cavity. By optimizing the proportion of each part of the biological filter of the three-phase biological fluidized bed, the height-diameter ratio is reduced; and the flow guide cylinder and the flow guide cover are arranged, and air is utilized for pushing, so that an aerobic environment required by nitrifying bacteria can be ensured, the filler can be fully fluidized, the mass transfer effect is enhanced, and a good treatment effect on ammonia nitrogen pollutants in aquaculture tail water is achieved.

Description

Technical Field

[0001] The invention belongs to the field of aquaculture tail water treatment, in particular to a circulating biological filter based on encapsulated nitrifying bacteria and an operation method thereof. Background Art

[0002] In recent years, the aquaculture industry has shown a strong development trend, and the breeding model has undergone significant changes, gradually changing from the traditional low-density and extensive type to the modern high-density and intensive direction. With the continuous improvement and innovation of breeding technology, the efficiency of aquaculture has been improved and the cost has been reduced, which has promoted its large-scale and industrialized development, but at the same time it has also brought a large number of aquaculture tailwater discharge and treatment problems. my country's aquaculture tailwater treatment technology is still in its infancy and is relatively lagging behind the needs of industrial development. This situation has caused concentrated breeding areas to face the severe situation of continuous deterioration of water quality, posing a threat to the stability of the ecosystem and the sustainable development of the fishery industry that cannot be ignored.

[0003] At present, the treatment of aquaculture tailwater is mainly carried out through physical filtration and the use of filter-feeding animals, aquatic plants, algae and microorganisms to absorb and remove solid particles and nutrients such as feces and bait residues in the tailwater. For example, fish-shellfish-algae mixed farming is adopted, or the aquaculture tailwater is discharged into an ecological pond for purification before discharge or recycling. However, ecological purification generally occupies a large area and will occupy a certain aquaculture area, which is difficult to implement and promote in areas with limited land. In addition, it often takes 2 to 3 growth cycles for animals and plants to achieve optimal efficiency in ecological purification, and they are easily affected by pests and diseases. At the same time, there are problems such as plant death and wintering, and there is a threshold for the absorption of dissolved pollutants, resulting in unstable treatment efficiency.

[0004] In the design of factory-scale recirculating aquaculture systems, the water treatment area generally accounts for 25%-30% of the aquaculture area. In order to achieve timely removal of particulate matter, the daily circulation of the recirculating aquaculture system can reach more than 20 times, resulting in a short hydraulic retention time of the biological filter in the water treatment system, most of which do not exceed 1 hour. In the treatment of pond aquaculture tailwater, in order to ensure the aquaculture area, when using biological filtration equipment to treat soluble pollutants, the biological filtration equipment occupies a small area, has limited volume, and has a short hydraulic retention time, and the water treatment efficiency is low. Generally speaking, the HRT of traditional sewage treatment reactors is optimal between 1h and 5h. There is a contradiction between the treatment area and the hydraulic retention time in the treatment of aquaculture tailwater. In addition, due to the low concentration of pollutants in the aquaculture water body, the types and number of denitrifying microorganisms are small, and they are usually at a disadvantage in interspecies competition, especially in the early stages of aquaculture. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a circulating biofilter based on encapsulated nitrifying bacteria and an operation method thereof, so as to solve the contradiction between the treatment area and the hydraulic retention time in the aquaculture tail water treatment in the prior art.

[0006] A circulating biofilter based on encapsulated nitrifying bacteria and an operation method thereof, comprising a conical bottom area V 1 , cylindrical reaction zone V 2 and three-phase separation zone V 3 , the three-phase separation zone V 3 The bottom of the cylindrical reaction zone V 2 The cylindrical reaction zone V 2 Bottom and conical bottom area V 1 Connected, three-phase separation zone V 3 The cylindrical reaction zone V is formed by a conical bottom cavity. 2 The conical bottom area V is formed by the reaction zone cavity. 1 Formed by the inner cavity of the overflow weir.

[0007] The conical bottom is connected to the water inlet bucket through a water inlet pipe, a water pump for controlling the water inlet flow is installed in the middle of the water inlet pipe, the bottom of the conical bottom is connected to the air inlet pipe, the other end of the air inlet pipe is connected to an aerator for aeration, the middle of the air inlet pipe is connected to a flow meter for controlling the air intake, and an air distribution plate is provided at the bottom of the conical bottom;

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

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

[0010] Preferably, the conical bottom area V 1 , cylindrical reaction zone V 2 and three-phase separation zone V 3 The volume ratio is V 2 =1.6V 3 =7V 1 .

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

[0012] Preferably, in the three-phase biological fluidized bed biofilter, the diameter of the air distribution plate is the same as the diameter of the conical bottom, and the diameter of the pores is 0.1-0.6 mm.

[0013] Preferably, in the three-phase biological fluidized bed biofilter, the trumpet-shaped opening at the bottom of the guide cover forms an oblique angle of 45° with the horizontal plane; and the conical bottom forms an oblique angle of 60° with the horizontal plane.

[0014] Preferably, in the three-phase biological fluidized bed biofilter, the guide tube is detachable and fixed by a pair of upper and lower fixing rings.

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

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

[0017] Preferably, the biofilter uses nitrifying bacteria filler, and the preparation method of the nitrifying bacteria filler is to centrifuge and filter press the enriched and cultured nitrifying activated sludge to dehydrate it to a moisture content of 70%-80%; use a polypropylene or nylon porous film with a pore size of 200-500nm, heat seal it at 150-180℃ to make a 3*3*0.3cm sheet-type packaged nitrifying bacteria filler, and the mass of nitrifying activated sludge per unit area is about 0.02-0.05g / cm 2 .

[0018] 10. A method for operating a circulating biofilter based on encapsulated nitrifying bacteria, comprising the following steps:

[0019] The first step: putting the nitrifying bacteria filler into the three-phase biological fluidized bed biofilter to carry out filler domestication;

[0020] Step 2: During the acclimation period, the influent ammonia nitrogen concentration is maintained at 5-15.0 mg / L, the pH value is 7.5-8.0, the dissolved oxygen is about 4 mg / L, and the water is changed every 24 hours until the acclimation is mature;

[0021] Step 3: Connect the reactor water inlet pipe and outlet pipe to the water inlet bucket, control the water inlet flow rate through the water pump, control the air intake through the flow meter, and start the circulation operation to degrade ammonia nitrogen;

[0022] Step 4: Until the low concentration ammonia nitrogen wastewater is completely removed.

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

[0024] 1. The present invention optimizes the proportions of various parts of the three-phase biological fluidized bed biological filter to reduce the height-to-diameter ratio; and sets a guide tube and a guide cover, which are pushed by air to ensure a good breeding environment for nitrifying bacteria and fully fluidize the filler, thereby enhancing the mass transfer effect and having a good treatment effect on ammonia nitrogen pollutants in aquaculture tail water.

[0025] 2. The present invention provides a large amount of highly active bacteria in a short time by encapsulating nitrifying bacteria, and has the advantages of maintaining high biological concentration, low sludge production, and strong resistance to toxic substances. It can shorten the reactor startup time, reduce the filler filling rate, and does not need to set up a separate mud-water separation device.

[0026] 3. The present invention circulates the three-phase biological fluidized bed biofilter, which 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, harmful substances such as ammonia nitrogen and nitrite can be completely removed within 24 hours.

[0027] 4. The present invention utilizes encapsulated nitrifying bacteria to increase the biomass of the reactor, and realizes efficient removal of ammonia nitrogen from aquaculture tail water in a very short hydraulic retention time under the gas-liquid-solid three-phase high-speed fluidization and circulation operation mode. It can reduce the area occupied by water treatment, improve water treatment efficiency, and reduce the cost of infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0031] Figure 4 is a schematic diagram of nitrite concentration during the acclimation period of the present invention;

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

[0033] In the figure: 1. serrated overflow weir, 2. water collecting cover, 3. three-phase separation guide cover, 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 bucket, 13. agitator, 14. water pump, 15. flow meter, 16. aerator, 17. valve, 18. fixing plate. DETAILED DESCRIPTION

[0034] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0035] like Figure 1 As shown, the present invention provides a circulating biofilter based on encapsulated nitrifying bacteria and an operation method thereof, comprising a conical bottom area V 1 , cylindrical reaction zone V 2 and three-phase separation zone V 3 , three-phase separation zone V 3 The bottom of the cylindrical reaction zone V 2 Connected, cylindrical reaction zone V 2 Bottom and conical bottom area V1 Connected, three-phase separation zone V 3 The conical bottom area V is formed by the inner cavity of the conical bottom 9. 1 , cylindrical reaction zone V 2 and three-phase separation zone V 3 The volume ratio is V 2 =1.6V 3 =7V 1 The cylindrical reaction zone V2 is formed by the inner cavity of the reaction zone 6, and the conical bottom area V1 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 connected to the water inlet bucket 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 water inlet pipe 8 and the valve 17 are arranged above the fixing ring 4. The 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 connected to the air inlet pipe 10. The other end of the air inlet pipe 10 is connected to the aerator 16 for aeration. The middle of the air inlet pipe 10 is connected to the flow meter 15 for controlling the air intake. The bottom of the conical bottom 9 is provided with an air distribution plate 11. The diameter of the air distribution plate 11 in the biofilter is the same as the bottom diameter of the conical bottom 9, and the pore diameter is 0.1-0.6mm.

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

[0038] An overflow weir 1 is installed on the top of the reaction zone 6 through a guide tube fixing ring 4. A water collecting cover 2 is arranged on the periphery of the overflow weir 1. The water collecting cover 2 is connected to a water outlet pipe 7. The water outlet pipe 7 is connected to a water inlet bucket 12. A valve 17 is installed on the water outlet pipe 7. An agitator 13 is arranged in the water inlet bucket 12.

[0039] refer to Figure 2 First, the enriched and cultured nitrifying activated sludge is centrifuged and filtered to dehydrate to a moisture content of 70%-80%; a polypropylene or nylon porous film with a pore size of 200-500nm is heat-sealed at 150-180°C to form a 3*3*0.3cm sheet-type packaged nitrifying bacteria filler, and the mass of nitrifying activated sludge per unit area is about 0.02-0.05g / cm2;

[0040] refer to Figure 3, the influent ammonia nitrogen concentration is 2-10.0mg / L, the pH value is 7.5-8.0, the filling rate of the thin-sheet packaged nitrifying bacteria filler in the reactor is 10%, the biomass is about 5000mg / L, and the hydraulic retention time is 15-30min. The influent is pumped into the reactor by a water pump, and the aeration in the reactor adopts blast aeration to maintain the high-speed fluidization of the thin-sheet packaged nitrifying bacteria filler, the gas-water ratio is 10-15, and the dissolved oxygen is about 4-8.0mg / L. After the high-speed fluidization reaction of gas, liquid and solid three-phases, the effluent returns to the water inlet bucket and enters the reactor for nitrification reaction for multiple cycles, which can achieve an ammonia nitrogen removal rate of more than 95% within 12-24h.

[0041] refer to Figure 4 , according to the filling rate of 10%, the above fillers were put into the three-phase biological fluidized bed biofilter for filler domestication. During the domestication period, the influent ammonia nitrogen concentration was maintained at 5-15.0 mg / L, the pH value was 7.5-8.0, the dissolved oxygen was about 4 mg / L, and the water was changed every 24 hours. The encapsulation method has little damage to nitrifying bacteria and the activity recovery is fast. The removal rate of 10 mg / L ammonia nitrogen in the influent reached more than 95% on the first day; 5 mg / L took two days; 15 mg / L took three days. The sub-salt was maintained in a lower concentration range of 0 to 0.12 mg / L, and the concentration was basically maintained at 0.01 mg / L after the 7th day.

[0042] When the acclimatization is mature, the reactor water inlet pipe 8 and the water outlet pipe 7 are connected to the water inlet bucket 12. The volume of the water inlet bucket is 4-8 times the volume of the reactor. The concentration of ammonia nitrogen in the inlet water is 2-10 mg / L. The water inlet flow rate is controlled by the water pump 14, and the hydraulic retention time is 15-30 min. The pH value is 7.5-8.0. The air intake is controlled by the flow meter 15, and the air-water ratio is controlled to 10. The dissolved oxygen is about 8.0 mg / L to start the circulation operation to degrade ammonia nitrogen;

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

[0044] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A circulating biofilter based on encapsulated nitrifying bacteria and its operation method, comprising a conical bottom area V1, a cylindrical reaction area V2 and a three-phase separation area 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 area V1. The three-phase separation zone V3 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 conical bottom area V1 is formed by the inner cavity of the overflow weir (1). The conical bottom (9) is connected to a water inlet bucket (12) through a water inlet pipe (8), a water pump (14) for controlling the water inlet flow rate is installed in the middle of the water inlet pipe (8), the bottom of the conical bottom (9) is connected to an air inlet pipe (10), the other end of the air inlet pipe (10) is connected to an aerator (16) for aeration, the middle of the air inlet pipe (10) is connected to a flow meter (15) for controlling the air inlet amount, and an air distribution plate (11) is provided at the bottom of the conical bottom (9); A detachable flow guide tube (5) is arranged at the center of the inner cavity of the reaction zone (6), a flow guide cover (3) is arranged above the flow guide tube (5), the inner diameter of the flow guide cover (3) is larger than the outer diameter of the flow guide tube (5), and the upper end of the flow guide cover (3) is open. An overflow weir (1) is installed at the top of the reaction zone (6) through a guide tube fixing ring (4), a water collecting cover (2) is arranged on the periphery of the overflow weir (1), the water collecting cover (2) is connected to a water outlet pipe (7), the water outlet pipe (7) is connected to a water inlet bucket (12), a valve (17) is installed on the water outlet pipe (7), and an agitator (13) is arranged in the water inlet bucket (12).

2. The circulating biofilter based on encapsulated nitrifying bacteria and the operation method thereof as claimed in claim 1, characterized in that: 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.

3. The circulating biofilter based on encapsulated nitrifying bacteria and the operation method thereof as claimed in claim 1, characterized in that: The water outlet of the overflow weir (1) is in a sawtooth shape.

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

5. The circulating biofilter based on encapsulated nitrifying bacteria and the operation method thereof as claimed in claim 1, characterized in that: The trumpet-shaped opening at the bottom of the deflector (3) forms an oblique angle of 45° with the horizontal plane; the conical bottom (9) forms an oblique angle of 60° with the horizontal plane.

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

7. The circulating biofilter based on encapsulated nitrifying bacteria and the operation method thereof as claimed in claim 1, characterized in that: The deflector cover (3) is detachable and connected to the water collecting cover (2) via a fixing plate (18).

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

9. The circulating biofilter based on encapsulated nitrifying bacteria and the operation method thereof as claimed in claim 1, characterized in that: The biological filter adopts nitrifying bacteria filler, and the preparation method of the nitrifying bacteria filler is as follows: centrifuging and filtering the enriched and cultured nitrifying activated sludge to dehydrate it to a moisture content of 70%-80%; using polypropylene or nylon porous film with a pore size of 200-500nm, heat-sealing at 150-180°C to form a 3*3*0.3cm sheet-type packaged nitrifying bacteria filler, and the mass of nitrifying activated sludge per unit area is about 0.02-0.05g / cm2.

10. A method for operating a circulating biofilter based on encapsulated nitrifying bacteria, as claimed in claims 1 to 9, characterized in that: The following steps are involved: The first step: putting the nitrifying bacteria filler into the three-phase biological fluidized bed biofilter to carry out filler domestication; Step 2: During the acclimation period, the influent ammonia nitrogen concentration is maintained at 5-15.0 mg / L, the pH value is 7.5-8.0, the dissolved oxygen is about 4 mg / L, and the water is changed every 24 hours until the acclimation is mature; Step 3: Connect the reactor water inlet pipe (8) and the water outlet pipe (7) to the water inlet bucket (12), control the water inlet flow rate through the water pump (14), control the air intake volume through the flow meter (15), and start the circulation operation to degrade ammonia nitrogen; Step 4: Until the low concentration ammonia nitrogen wastewater is completely removed.

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