BDD electrocatalytic oxidation-based seawater recirculating aquaculture purification method and BDD electrocatalytic oxidation-based seawater recirculating aquaculture purification system

Abstract

The invention provides a seawater circulating aquaculture purification method and system based on BDD electrocatalytic oxidation, and belongs to the technical field of water treatment. The seawater circulating aquaculture purification method provided by the invention is high in feasibility, economical and practical, simple in system equipment, small in occupied area and convenient to use. According to the method provided by the invention, BDD electrocatalytic oxidation is adopted as a core process, the process flow is short, the operation is simple, the occupied area is small, and active chlorine generated by BDD electrocatalytic oxidation is fully utilized in a mixing manner, so that residual chlorine is removed with low energy consumption, and the breeding safety is ensured. The corresponding number of reactors can be started in time according to different circulating water amounts and water qualities, and the treatment effect is stable. Upgrading of an industrial recirculating aquaculture technology is promoted, the aquaculture density can be effectively improved, and meanwhile pollutants discharged by a seawater recirculating aquaculture system are remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a seawater circulating aquaculture purification method based on BDD electrocatalytic oxidation and a system thereof. Background Art

[0002] Factory-scale recirculating aquaculture is also known as land-based factory farming, factory farming, industrial fish farming, etc. It is an aquaculture technology that meets the needs of modern fishery farming. It has the characteristics of high production efficiency and small footprint. It is generally called recirculating aquaculture abroad. Its main features are the recycling of water bodies, controlling the living environment of farmed organisms, and scientific management, thereby getting rid of the restrictions of natural resource conditions such as land and water. It is a high-density, high-yield, high-input, and high-efficiency farming method. High ammonia nitrogen in the recirculating aquaculture system will reduce the immunity of fish and shrimp, causing fish and shrimp diseases and even death; nitrite will oxidize ferrous hemoglobin into methemoglobin that does not have the function of transporting oxygen. Oxygen cannot be transported normally, causing hypoxia and the death of fish and shrimp. Therefore, ammonia nitrogen and nitrite nitrogen are both control indicators for recirculating aquaculture. The recirculating aquaculture system will be equipped with nitrification and denitrification filters for microbial treatment. However, since marine aquaculture wastewater is low-pollution wastewater with low COD, nitrogen and phosphorus, and insufficient nutrition, the microorganisms in the nitrification and denitrification filters are difficult to cultivate and there is a certain degree of instability. It is necessary to discharge and supplement some water at the same time to reduce these two indicators.

[0003] Chinese patent CN 116161822 A discloses a factory-scale circulating water aquaculture water treatment system based on electrochemical treatment, which includes a breeding pond, a pre-treatment unit, an electrochemical treatment module and a post-treatment unit. The pre-treatment unit includes a microfilter connected to the breeding pond, and also includes a buffer tank, a circulating water pump and a precision filter arranged in sequence. The buffer tank is also connected to a protein separator. The electrochemical treatment module degrades ammonia nitrogen and sterilizes microorganisms by performing electrolytic oxidation reaction on the water body. The post-treatment unit is used to remove the by-products of electrolysis of the electrochemical treatment module.

[0004] However, this system has a long process flow, high investment cost and complicated operation. Summary of the invention

[0005] The object of the present invention is to provide a seawater circulating aquaculture purification method and system based on BDD electrocatalytic oxidation, which has high process feasibility, is economical and practical, has simple equipment, occupies a small area, and is easy to use.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation, comprising a fish pond, a microfilter, a microfilter pump pool, BDD electrocatalytic oxidation treatment equipment, an aeration tank and an oxygenation device;

[0008] The fish culture pond, microfiltration machine, microfiltration machine pump pool, aeration tank and oxygenation equipment are connected in sequence;

[0009] The water inlet and outlet pipes of the BDD electrocatalytic oxidation treatment equipment are connected to the microfiltration machine pump pool.

[0010] Preferably, an aeration plate is placed in the microfiltration machine pump pool to allow the effluent from the BDD electrocatalytic oxidation treatment equipment to be fully mixed with the circulating water in the microfiltration machine pump pool.

[0011] Preferably, the outlet pipe of the BDD electrocatalytic oxidation treatment equipment, the water extraction point of the microfiltration pump pool and the water outlet of the aeration tank are respectively provided with residual chlorine sensors to monitor the active chlorine concentration in the system.

[0012] Preferably, the BDD electrocatalytic oxidation treatment equipment includes a reactor frame, an electric control cabinet, a pickling water tank, a clean water tank and a plurality of buffer water buckets.

[0013] Preferably, a plurality of reactors are arranged in the reactor frame;

[0014] Each reactor has 8 sets of electrode group units built in, each electrode group unit contains 8 BDD anodes, and the two sets of electrode groups are connected in series for power supply.

[0015] Preferably, the middle and bottom parts of the plurality of buffer water buckets are connected by a water channel to form an integrated water bucket.

[0016] The present invention also provides a seawater circulating aquaculture purification method based on BDD electrocatalytic oxidation, comprising the following steps:

[0017] S1, the water from the fish pond passes through the microfiltration machine to remove suspended solids in the water, and then enters the microfiltration machine pump pool;

[0018] S2, BDD electrocatalytic oxidation equipment pumps water from the microfilter pump pool, processes it in the reactor, and then enters the buffer water bucket, discharging gas byproducts and calcium and magnesium precipitates;

[0019] S3, the treated effluent is returned to the microfiltration machine pump pool, and the effluent from the BDD electrocatalytic oxidation treatment equipment is fully mixed with the water in the microfiltration machine pump pool through aeration, and the direct oxidation and indirect oxidation of BDD electrocatalytic oxidation are used to remove ammonia nitrogen, nitrite and microorganisms in the seawater aquaculture circulating water;

[0020] S4, the water from the microfiltration pump pool enters the aeration tank, and the underutilized residual chlorine is removed through aeration, and the residual chlorine is treated to a range that is safe for farmed fish;

[0021] S5. The water from the aeration tank is returned to the fish pond after passing through the oxygenation device to increase the dissolved oxygen in the water, thus completing the cycle.

[0022] Preferably, the gaseous byproducts in the buffer water bucket are discharged through an exhaust fan, while the intake fan draws air to dilute the hydrogen concentration in the bucket.

[0023] Preferably, the calcium and magnesium precipitates in the buffer water bucket are discharged regularly through a sewage outlet.

[0024] Beneficial effects of the present invention:

[0025] The method provided by the present invention adopts BDD electrocatalytic oxidation as the core process, has a short process flow, is simple to operate, occupies a small area, and fully utilizes the active chlorine generated by BDD electrocatalytic oxidation in a mixed manner, thereby achieving low-energy removal of residual chlorine and ensuring aquaculture safety. The corresponding number of reactors can be started in time according to the amount and quality of circulating water, and the treatment effect is stable. It promotes the upgrading of industrial circulating aquaculture technology, can effectively increase aquaculture density, and significantly reduce pollutants discharged from seawater circulating aquaculture systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the electrocatalytic oxidation device used in the present invention, wherein 1-microfiltration pump pool; 2-reactor; 3-clean water tank; 4-acid washing water tank; 5-sampling valve; 6-buffer barrel; 7-drainage outlet; 8-air inlet fan; 9-exhaust fan;

[0028] Figure 3 This is a rendering of the experimental process of applying the system of the present invention. DETAILED DESCRIPTION

[0029] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0030] Example

[0031] The seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation provided by the present invention includes a fish pond, a microfilter, a microfilter pump pool, a BDD electrocatalytic oxidation treatment equipment, a residual chlorine sensor, an aeration tank and an oxygenation equipment. The inlet and outlet pipes of the BDD electrocatalytic oxidation treatment system are connected to the microfilter pump pool. The microfilter is used to remove suspended matter. The inlet and outlet pipes of the BDD electrocatalytic oxidation treatment system are connected to the microfilter pump pool and an aeration plate is placed in the microfilter pump pool to fully mix the electrocatalytic oxidation effluent with the circulating water in the pump pool, and the active chlorine in the effluent is used to remove ammonia nitrogen, nitrite and microorganisms in the water; residual chlorine sensors are arranged at the water outlet of the BDD electrocatalytic oxidation treatment system, the water extraction point of the microfilter pump pool and the water outlet of the aeration tank to monitor the active chlorine concentration in the purification system in real time. The process flow chart is shown as follows Figure 1 shown.

[0032] Electrocatalytic oxidation equipment Figure 2 shown.

[0033] The BDD electrocatalytic oxidation treatment equipment is mainly composed of a reactor frame (with 8 reactors installed on top), an electric control cabinet, a pickling water tank, a clean water tank, two buffer water buckets (connected at the bottom), and related water and gas circuits.

[0034] Brief description of each part:

[0035] Electric control box: built-in power supply and distribution unit, PLC control unit, 4 DC adjustable power supplies. The system power supply and distribution unit is responsible for distributing power to each component of the system, the PLC is responsible for system process control, and each DC adjustable power supply provides constant current power supply to two reactors (connected in series) at the same time.

[0036] Reactor: It has 8 sets of electrode units built in, each electrode unit contains 8 BDD anodes (240mm*130mm), and the two sets of electrode units are powered in series, providing a total BDD electrode area of ​​about 3.6 square meters.

[0037] Acid washing tank and clean water tank: The pickling process is to first use the acid in the acid washing tank to pickle the reactor and pipelines, and then flush them with clean water in the clean water tank to reduce the capacity of the acid brought into the microfiltration machine pump pool. The volume of the acid washing tank and the clean water tank is 300L.

[0038] Cache bucket: The main function of the cache bucket is to prevent hydrogen and chlorine generated during the electrocatalytic oxidation reaction from entering the microfiltration pump pool and fish farming workshop. In addition, the treated circulating water is precipitated to remove some calcium and magnesium precipitates. The cache bucket uses two 3000L vertical cone buckets, which are connected by a water channel at the middle and bottom to form an integrated bucket, and the cone bottom is equipped with a sewage outlet.

[0039] In this embodiment, the processing system is applied to a seawater circulating aquaculture plant in Shandong.

[0040] The specific experimental design is as follows:

[0041] Experimental scale: 50m 3

[0042] Experimental fish species: Yellow-banded snapper

[0043] Number of experimental fish: 2000, average weight 60 grams

[0044] Sampling point: fish pond water

[0045] The specific method is as follows:

[0046] Step 1: After installing the system, feed the experimental fish normally, turn off the equipment to accumulate ammonia nitrogen and nitrite. Turn on the equipment when the accumulation reaches above 0.4 mg / L.

[0047] Step 2: The water from the fish pond passes through a microfiltration machine to remove suspended solids in the water and then enters the microfiltration machine pump pool.

[0048] Step 3: The BDD electrocatalytic oxidation equipment draws water from the microfilter pump pool 1 and enters the buffer tank after being processed by the reactor. In the buffer tank, the gas byproducts such as hydrogen generated during the BDD electrocatalytic oxidation process are discharged through the exhaust fan, and the intake fan draws air to dilute the hydrogen concentration in the tank to ensure production safety; the calcium and magnesium precipitates generated during the reaction sink to the bottom of the buffer tank and are discharged regularly through the sewage outlet.

[0049] Step 4: The treated effluent is returned to the microfiltration pump tank. After aeration, the effluent from the BDD electrocatalytic oxidation treatment equipment is fully mixed with the water in the microfiltration pump tank. The direct oxidation and indirect oxidation of BDD electrocatalytic oxidation are used to remove ammonia nitrogen, nitrite and microorganisms in the seawater aquaculture circulating water.

[0050] (BDD - The electrocatalytic oxidation of organic matter, ammonia nitrogen, nitrite nitrogen and other pollutants in circulating water by boron-doped diamond film electrodes can be divided into direct oxidation and indirect oxidation. Direct oxidation refers to the direct oxidation of organic matter, ammonia nitrogen, nitrite nitrogen and other pollutants on the inert boron-doped diamond film anode surface by losing electrons and being oxidized; indirect oxidation refers to the strong oxidizing substances produced on the anode surface further oxidizing the pollutants in the tail water and disinfecting and sterilizing them, killing harmful bacteria and viruses such as Escherichia coli in the tail water. At the same time, the cathode plate plays a role in reducing nitrite nitrogen and nitrate nitrogen to nitrogen gas)

[0051] Step 5: The water from the microfiltration pump enters the aeration tank, where aeration removes the underutilized residual chlorine and reduces the residual chlorine to a range that is safe for farmed fish.

[0052] Step 6: The effluent from the aeration tank is returned to the fish pond after passing through an oxygenation device to increase the dissolved oxygen in the water. Samples are taken at the water addition point of the fish pond to check water quality parameters such as ammonia nitrogen, nitrite, bacteria, Vibrio, CODMn, and total nitrogen.

[0053] The experimental process is as follows Figure 3 As shown:

[0054] When the electrocatalytic oxidation equipment was turned off, the ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the circulating water of the experimental workshop all showed an upward trend.

[0055] The equipment was turned on on January 16, and the ammonia nitrogen concentration decreased, while the nitrite nitrogen and nitrate nitrogen concentrations were still rising.

[0056] On January 17, the treatment current was increased, and the ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the water added to the fish pond decreased significantly, until they reached equilibrium on January 19. On January 20, the concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the water added to the fish pond did not change significantly. From January 17 to January 20, the residual chlorine concentration in the water added to the fish pond was controlled at 0.01 mg / L, and the experimental fish were in good condition and fed normally.

[0057] The equipment was shut down on January 21, and nitrite nitrogen and ammonia nitrogen accumulated. From January 22 to January 24, the equipment was turned on again. The downward trend of ammonia nitrogen and nitrite nitrogen concentrations in the fish pond water was similar to the downward trend from January 17 to January 20, and the residual chlorine concentration was 0 mg / L.

[0058] The equipment was turned on on January 25, using high current for short-time treatment, and the treatment effects on various water quality indicators were obvious.

[0059] The specific experimental data are shown in Table 1 below:

[0060] Table 1 System operation experimental data

[0061]

[0062] It can be seen from the above embodiments that the system provided by the present invention can achieve excellent circulation treatment effect. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation, characterized in that: Including fish ponds, microfiltration machines, microfiltration pump pools, BDD electrocatalytic oxidation treatment equipment, aeration tanks and oxygenation equipment; The fish culture pond, microfiltration machine, microfiltration machine pump pool, aeration tank and oxygenation equipment are connected in sequence; The water inlet and outlet pipes of the BDD electrocatalytic oxidation treatment equipment are connected to the microfiltration machine pump pool.

2. The seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation according to claim 1 is characterized in that: An aeration plate is placed in the microfilter pump pool to fully mix the effluent from the BDD electrocatalytic oxidation treatment device with the circulating water in the microfilter pump pool.

3. The seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation according to claim 1 is characterized in that: The outlet pipe of the BDD electrocatalytic oxidation treatment equipment, the water extraction point of the microfiltration pump pool and the water outlet of the aeration tank are respectively provided with residual chlorine sensors to monitor the active chlorine concentration in the system.

4. The seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation according to claim 1 is characterized in that: The BDD electrocatalytic oxidation treatment equipment includes a reactor frame, an electric control cabinet, a pickling water tank, a clean water tank and a plurality of buffer water buckets.

5. The seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation according to claim 4 is characterized in that: A plurality of reactors are arranged in the reactor frame; Each reactor has 8 sets of electrode group units built in, each electrode group unit contains 8 BDD anodes, and the two sets of electrode groups are connected in series for power supply.

6. The seawater circulating aquaculture purification system based on BDD electrocatalytic oxidation according to claim 4 is characterized in that: The middle and bottom parts of the plurality of buffer water buckets are connected through a water channel to form an integrated water bucket.

7. A seawater circulating aquaculture purification method based on BDD electrocatalytic oxidation, characterized in that: The following steps are involved: S1, the effluent from the fish pond passes through a microfiltration machine to remove suspended solids in the water, and then enters the microfiltration machine pump pool; S2, BDD electrocatalytic oxidation equipment pumps water from the microfilter pump pool, processes it in the reactor, and then enters the buffer water bucket, discharging gas byproducts and calcium and magnesium precipitates; S3, the treated effluent is returned to the microfiltration machine pump pool, and the effluent from the BDD electrocatalytic oxidation treatment equipment is fully mixed with the water in the microfiltration machine pump pool through aeration, and the direct oxidation and indirect oxidation of BDD electrocatalytic oxidation are used to remove ammonia nitrogen, nitrite and microorganisms in the seawater aquaculture circulating water; S4, the water from the microfiltration pump pool enters the aeration tank, and the underutilized residual chlorine is removed through aeration, and the residual chlorine is treated to a range that is safe for farmed fish; S5. The water from the aeration tank is returned to the fish pond after passing through the oxygenation device to increase the dissolved oxygen in the water, thus completing the cycle.

8. The seawater circulating aquaculture purification method based on BDD electrocatalytic oxidation according to claim 7, characterized in that: The gas byproducts in the buffer water bucket are discharged through the exhaust fan, and the intake fan draws air to dilute the hydrogen concentration in the bucket.

9. The method for purifying seawater circulating aquaculture based on BDD electrocatalytic oxidation according to claim 7, characterized in that: The calcium and magnesium precipitates in the buffer water bucket are discharged regularly through the sewage outlet.

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