Deep treatment process for soft-shelled turtle culture tail water

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a soft-shelled turtle breeding tail water advanced treatment process which comprises the following steps: S1, breeding tail water is introduced into a pretreatment tank, sequentially passes through a fence, an inclined tube settling zone, an oxygenation zone, an elastic filler zone and an adsorption filtration zone and then is discharged, BOD5 / TN in the discharged tail water is greater than or equal to 5.5, and BOD5 / CODcr is greater than 0.45; s2, the aquaculture tail water passing through the pretreatment tank is pumped into an adjusting sedimentation tank for water quality adjustment and then enters an A / A / O treatment tank for phosphorus and nitrogen removal; and S3, adding a phosphorus removal agent into the tail water passing through the A / A / O treatment tank, then pumping the tail water into an MBR membrane tank to remove activated sludge and macromolecular organic matters in the tail water, pumping the treated tail water into a disinfection tank for disinfection, and then discharging the tail water for use. According to the treatment method disclosed by the invention, the pretreatment tank is additionally arranged, and a plurality of pretreatment units are arranged in the pretreatment tank, so that the biodegradability of the aquaculture tail water can be improved, and the treatment effect of the aquaculture tail water is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a deep treatment process for turtle breeding tail water. Background Art

[0002] Soft-shelled turtle aquaculture tailwater is the water discharged during the aquaculture process after its quality has changed due to factors such as the metabolism of the farmed animals, feed residues, drug use, and various biological activities in the water. Currently, tailwater generated during aquaculture, such as soft-shelled turtle aquaculture, contains large amounts of organic matter and pollutants such as nitrogen and phosphorus. Phosphorus is primarily found in suspended matter such as excrement and leftover feed, while nitrogen primarily consists of nitrate nitrogen and a small amount of ammonia nitrogen. Therefore, if this tailwater is discharged without treatment, it will pollute the surrounding environment.

[0003] Traditional aquaculture tailwater is mostly treated by sedimentation and filtration. During the treatment process, the residual bait and excrement in the tailwater are precipitated (sedimentation tank) and filtered (such as filter dam or biofilm treatment), and the filtered sewage is directly discharged. However, after being treated by traditional treatment methods, aquaculture tailwater usually still contains high levels of organic matter and pollutants such as nitrogen and phosphorus. In addition, the concentration of pollutants in factory aquaculture tailwater is even higher. Since 2023, various parts of the country have issued their own "Aquaculture Tailwater Discharge Standards", requiring that the effluent COD, total nitrogen and total phosphorus are generally within 10mg / L, 3mg / L and 0.5mg / L. Therefore, there is an urgent need for a method for treating aquaculture tailwater with better treatment effects. Summary of the Invention

[0004] In order to solve the technical problem that existing aquaculture tail water treatment methods have poor treatment effects, the present invention adds a pretreatment tank to the treatment method and sets multiple pretreatment units in the pretreatment tank, which can improve the biodegradability of aquaculture tail water and thus improve the treatment effect of aquaculture tail water.

[0005] The present invention provides a turtle breeding tail water deep treatment process, which is characterized by comprising the following steps: S1. The aquaculture tail water is introduced into the pretreatment tank and discharged after passing through the fence, inclined tube sedimentation area, oxygenation area, elastic filler area and adsorption filtration area in sequence. The BOD5 / TN ratio of the discharged tail water is greater than or equal to 5.5 and the BOD5 / CODcr is greater than 0.40. S2, the aquaculture tail water after the pretreatment tank is pumped into the regulating sedimentation tank to adjust the water quality and then enters the A / A / O treatment tank for phosphorus and nitrogen removal; S3. Add phosphorus removal agent to the tail water after passing through the A / A / O treatment tank, then pump it into the MBR membrane tank to remove activated sludge and large molecular organic matter in the tail water, and then pump the treated tail water into the disinfection tank for disinfection and discharge for use.

[0006] Furthermore, in step S1, the tail water stays in the inclined tube sedimentation zone for 2 to 3 hours, stays in the oxygenation zone for 0.5 to 1 hour, and stays in the elastic filler zone and the adsorption filtration zone for 1 to 2 hours.

[0007] Furthermore, in step S1, the dissolved oxygen content in the discharged tail water is 2-3 mg / L.

[0008] Furthermore, in step S2, the A / A / O treatment tank includes an anaerobic tank, an anoxic tank and an aerobic tank arranged in sequence, the dissolved oxygen in the anaerobic tank is less than 0.4 mg / L, the dissolved oxygen in the anoxic tank is less than 0.5 mg / L, the pH of the aerobic tank is 7-8, the dissolved oxygen in the aerobic tank is 2-4 mg / L, and the sludge concentration in the aerobic tank is 4-5 g / L.

[0009] Furthermore, in step S2, the tail water stays in the anaerobic tank for 1-2 hours, in the anoxic tank for 2-3 hours, and in the aerobic tank for 6-7 hours.

[0010] Furthermore, in step S3, the treatment time in the MBR membrane pool is 4-6 hours, the flux F of the MBR membrane is 1.56 m3 / (m2·d), the membrane pore size is 30 nm, and the maximum membrane flux is 3.6 m3 / (m2·d); the content of activated sludge in the MBR membrane pool is 3500-4000 mg / L.

[0011] The beneficial effects of the present invention are: The present invention aims to solve the technical problem that the COD index in aquaculture tail water is high (greater than 1000 mg / L), direct treatment has poor biodegradability and leads to poor treatment effect. By adding a pretreatment tank, arranging filtration, oxygenation, elastic filler and adsorption filtration treatment steps in the pretreatment tank, the biodegradability of aquaculture tail water can be greatly improved, the difficulty and cost of subsequent treatment are reduced, and the treatment effect of aquaculture tail water is effectively improved, so that the effluent can meet the provincial first-level water quality discharge standard and can be recycled without further treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic structural diagram of an aquaculture tailwater treatment system according to an embodiment of the present invention; Figure 2 Schematic diagram of the structure of the pretreatment tank in an embodiment of the present invention.

[0013] Figure numerals: 1. Pretreatment tank; 2. Adjustment sedimentation tank; 3. A / A / O treatment tank; 4. MBR membrane tank; 5. Disinfection tank; 6. Blower room; 7. Sludge treatment unit; 8. First return pipe; 9. Second return pipe; 10. Third return pipe; 101. Fence; 102. V-type filter; 103. Inclined pipe; 104. Oxygenation zone; 105. Elastic filler zone; 106. Adsorption filtration zone. DETAILED DESCRIPTION

[0014] The following will describe in detail specific embodiments of the present invention with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects. Example

[0015] The present invention provides a method for deep treatment of turtle breeding tail water, which is based on the following Figure 1-2 The treatment system shown in the figure is implemented. The treatment system includes a pretreatment tank 1, a regulating sedimentation tank 2, an A / A / O treatment tank 3, an MBR membrane tank 4, and a disinfection tank 5, which are connected in sequence. The water inlet of the pretreatment tank 1 is connected to the water outlet of the aquaculture pond. The aquaculture tailwater enters the treatment system through the pretreatment tank 1 for water purification.

[0016] In this embodiment, the pretreatment tank 1 is a ring ditch. The main body of the ring ditch is built with cement and hollow ceramsite bricks. The ring ditch is 400 meters long, 5 meters wide and 1.5 meters deep, and can treat aquaculture tailwater from about 70,000 square meters of aquaculture ponds.

[0017] In this embodiment, the ring ditch is provided with a fence 101, an inclined pipe 103 sedimentation area, an oxygenation area 104, an elastic filler area 105 and an adsorption filtration area 106 in sequence, wherein the fence 101 is provided at the water inlet of the ring ditch, so that the suspended matter in the aquaculture tail water can be quickly filtered out. A continuous V-shaped filter 102 is provided at the bottom of the inclined pipe 103 sedimentation area, and staggered inclined pipes 103 are provided on the upper part. The length of a single cell of the V-shaped filter 102 is 5 meters and the height is 0.5 meters. A scraper and a sewage outlet are provided at the bottom of the V-shaped filter 102. In this embodiment, the length of a single inclined pipe 103 is 1 meter and the diameter is 50 mm. A plurality of microporous oxygenation devices are provided at the bottom of the oxygenation area 104 for reoxygenating the aquaculture tail water. The microporous oxygenation device belongs to the prior art and will not be described in detail here. Aeration zone 104 is connected to elastic filler zone 105, which comprises a continuous, dense layer of biological brushes. In this embodiment, four layers of biological brushes are provided. Arranging the biological brushes in layers facilitates subsequent replacement. Behind elastic filler zone 105 is adsorption and filtration zone 106, with adsorption material (including one or more of volcanic rock, attapulgite, and activated carbon) applied to its bottom. Submerged plants are planted on the adsorption material.

[0018] In this embodiment, a lifting pump is provided at the outlet of the pretreatment tank 1, and the lifting pump pumps the aquaculture tail water passing through the pretreatment tank 1 into the regulating sedimentation tank 2. The regulating sedimentation tank 2 includes a fine grid, an aerated grit chamber and a membrane grid arranged in sequence.

[0019] The outlet of the regulating sedimentation tank 2 is connected to the inlet of the A / A / O treatment tank 3. The A / A / O treatment tank 3 includes an anaerobic tank, an anoxic tank, and an aerobic tank arranged in sequence. The anaerobic tank and the anoxic tank are provided with submersible mixers at the bottom, and the aerobic tank is provided with an aeration device. A first return pipe 8 is provided at the bottom of the aerobic tank to connect to the anoxic tank, and a second return pipe 9 is provided at the bottom of the anoxic tank to connect to the anaerobic tank. The aerobic tank is provided with a drainage pipe to connect to the MBR membrane tank 4. The drainage pipe is provided with a dosing port for adding a dephosphorization agent. A third return pipe 10 is provided at the bottom of the MBR membrane tank 4 to connect to the aerobic tank.

[0020] The outlet of the MBR membrane tank 4 is provided with a water production pump, which pumps the tail water into the disinfection tank 5 for disinfection. In this embodiment, the disinfection tank 5 is provided with an ultraviolet disinfection device. The ultraviolet disinfection device is prior art and will not be described in detail here.

[0021] In this embodiment, the aquaculture tailwater treatment system also includes a blower room 6 and a sludge treatment unit 7. The blower room 6 is equipped with ventilation ducts connecting the conditioning sedimentation tank 2, the A / A / O treatment tank 3, and the MBR membrane tank 4. The sludge treatment unit 7 includes a sludge storage tank, a dewatering room, and a sludge shed, which are arranged in that order. The sludge storage tank is equipped with sludge ducts connecting the pretreatment tank 1, the conditioning sedimentation tank 2, and the MBR membrane tank 4. The dewatering room is equipped with a filter press.

[0022] In this embodiment, a turtle farming tail water deep treatment process includes the following steps: S1. The aquaculture tail water is introduced into the pretreatment tank and discharged after passing through the fence, inclined tube sedimentation area, oxygenation area, elastic filler area and adsorption filtration area in sequence. The BOD5 / TN ratio of the discharged tail water is greater than or equal to 5.5 and the BOD5 / CODcr is greater than 0.40. Specifically, tailwater from the aquaculture ponds first enters the pretreatment tank. Suspended matter in the tailwater is intercepted by a fence, and then the tailwater enters the inclined tube sedimentation zone, where it remains for 2-3 hours. Gravity traps sediment in the V-shaped filter. After the upper tailwater passes through the inclined tube, the sediment is also trapped at the bottom of the tube. After the tailwater has passed through the inclined tube sedimentation zone, it enters the aeration zone, where it remains for 0.5-1 hour. Microporous aeration devices are then used to re-oxygenate the tailwater, ensuring it reaches self-purification conditions. After passing through the aeration zone, the dissolved oxygen content is between 2-3 mg / L. The re-oxygenated tailwater then passes through the elastic packing zone, where bio-brushes enhance microbial attachment and improve the system's ability to degrade pollutants. Finally, it passes through the adsorption filtration zone, where adsorbent materials and submerged plants absorb small molecules from the tailwater. The residence time in both the elastic packing zone and the adsorption filtration zone is 1-2 hours. After pretreatment, the BOD5 / TN of the aquaculture tail water is greater than or equal to 5.5, and the BOD5 / CODcr is greater than 0.45, and its biodegradability reaches a good standard.

[0023] S2, the aquaculture tail water after the pretreatment tank is pumped into the regulating sedimentation tank to adjust the water quality and then enters the A / A / O treatment tank for phosphorus and nitrogen removal; Specifically, the pre-treated aquaculture tailwater is pumped into a regulating sedimentation tank, where it is homogenized, further desilted, and the effluent is adjusted before entering the A / A / O treatment tank. The A / A / O treatment tanks are initially set to have a dissolved oxygen level of less than 0.4 mg / L in the anaerobic tank and less than 0.5 mg / L in the anoxic tank. The pH in the aerobic tank is set to 7-8, the dissolved oxygen level in the aerobic tank is set to 2-4 mg / L, and the sludge concentration in the aerobic tank is set to 4-5 g / L. After entering the tanks, the tailwater is retained in the anaerobic tank for 1-2 hours, in the anoxic tank for 2-3 hours, and in the aerobic tank for 6-7 hours.

[0024] S3. Add phosphorus removal agent to the tail water after passing through the A / A / O treatment tank, then pump it into the MBR membrane tank to remove activated sludge and large molecular organic matter in the tail water, and then pump the treated tail water into the disinfection tank for disinfection and discharge for use.

[0025] Specifically, the flux F of the MBR membrane in the MBR membrane pool is set to 1.56 m 3 / (m 2 ·d), the membrane pore size is 30nm, and the maximum membrane flux is 3.6 m 3 / (m 2 d) The activated sludge content in the MBR membrane tank is 3500-4000 mg / L. After treatment in the A / A / O treatment tank, the tailwater is treated with a phosphorus removal agent and allowed to remain in the MBR membrane tank for 4-6 hours. After treatment, it enters the disinfection tank for UV disinfection, and the effluent is recycled.

[0026] Although the embodiments of the present invention have been described herein, those skilled in the art will appreciate that the embodiments herein may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. A turtle breeding tail water deep treatment process, characterized in that: The following steps are involved: S1. The aquaculture tail water is introduced into the pretreatment tank and discharged after passing through the fence, inclined tube sedimentation area, oxygenation area, elastic filler area and adsorption filtration area in sequence. The BOD5 / TN ratio of the discharged tail water is greater than or equal to 5.5 and the BOD5 / CODcr is greater than 0.

40. S2, the aquaculture tail water after the pretreatment tank is pumped into the regulating sedimentation tank to adjust the water quality and then enters the A / A / O treatment tank for phosphorus and nitrogen removal; S3. Add phosphorus removal agent to the tail water after passing through the A / A / O treatment tank, then pump it into the MBR membrane tank to remove activated sludge and large molecular organic matter in the tail water, and then pump the treated tail water into the disinfection tank for disinfection and discharge for use.

2. The deep treatment process for turtle breeding tail water according to claim 1, characterized in that: In step S1, the tail water stays in the inclined tube sedimentation zone for 2 to 3 hours, stays in the oxygenation zone for 0.5 to 1 hour, and stays in the elastic filler zone and the adsorption filtration zone for 1 to 2 hours.

3. The deep treatment process for turtle breeding tail water according to claim 1, characterized in that: In step S1, the dissolved oxygen content in the discharged tail water is 2-3 mg / L.

4. A turtle breeding tail water deep treatment process as claimed in claim 4, characterized in that: In step S2, the A / A / O treatment tank includes an anaerobic tank, an anoxic tank and an aerobic tank arranged in sequence. The dissolved oxygen in the anaerobic tank is less than 0.4 mg / L, the dissolved oxygen in the anoxic tank is less than 0.5 mg / L, the pH of the aerobic tank is 7-8, the dissolved oxygen in the aerobic tank is 2-4 mg / L, and the sludge concentration in the aerobic tank is 4-5 g / L.

5. The deep treatment process for turtle breeding tail water according to claim 5, characterized in that: In step S2, the tail water stays in the anaerobic tank for 1-2 hours, in the anoxic tank for 2-3 hours, and in the aerobic tank for 6-7 hours.

6. The deep treatment process for turtle breeding tail water according to claim 1, characterized in that: In step S3, the treatment time in the MBR membrane pool is 4-6 hours, and the flux F of the MBR membrane is 1.56 m 3 / (m 2 d), the membrane pore size is 30nm, and the maximum membrane flux is 3.6m 3 / (m 2 d) The activated sludge content in the MBR membrane tank is 3500-4000 mg / L.

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