CN105502584A - Device and method for removing ammonia nitrogen, nitrite nitrogen and COD in marine culture wastewater - Google Patents

Abstract

The invention discloses a device and a method for removing ammonia nitrogen, nitrite nitrogen and COD from seawater aquaculture wastewater. A water inlet is provided on the top of the reservoir, and the water inlet communicates with the water outlet at the upper end of the electrochemical reactor, and a water outlet is provided at the lower end of the reservoir, and the water outlet is connected with the water inlet at the lower end of the electrochemical reactor through a peristaltic pump; The reactor is equipped with an anode, a bipolar electrode and a cathode in sequence, the anode is connected to the positive pole of the DC stabilized voltage power supply, and the cathode is connected to the negative pole of the DC stabilized voltage power supply. It does not require additional chemicals, which can greatly reduce the treatment cost; free chlorine is continuously generated in situ at the anode, which improves safety performance; the treatment process is clean and fast, and does not generate sludge and secondary pollution; ammonia nitrogen, nitrite nitrogen and The removal rate of COD is fast and the efficiency is high; it only needs to control the magnitude of the current, which is easy to control; the device is simple and easy to operate and maintain.

Description

Device and method for removing ammonia nitrogen, nitrite nitrogen and COD from mariculture wastewater

technical field

The invention relates to a water treatment device and method, in particular to a device and method for removing ammonia nitrogen, nitrite nitrogen and COD from seawater aquaculture wastewater.

Background technique

The aquaculture industry has developed rapidly in recent years. The discharge of a large amount of aquaculture wastewater has caused a huge impact on the surrounding environment, the deterioration of the water environment, frequent red tides, and the destruction of ecological balance and biodiversity. The decline in water quality in aquaculture waters has also brought huge losses to my country's fishery economy. Ammonia nitrogen, nitrite nitrogen and COD are the main pollutants in aquaculture wastewater, and they are also the most difficult to remove. At present, there are relatively few technologies specifically aimed at aquaculture wastewater, and most of them refer to the traditional sewage treatment methods. For seawater systems, the salinity effect in seawater and the difference between the pollution structure in aquaculture wastewater and common land-based sewage increase the difficulty of aquaculture wastewater treatment.

At present, the advanced treatment of ammonia nitrogen, nitrous nitrogen and COD can be divided into three categories: physical, chemical and biological. Among them, physical treatment methods mainly include filtration-adsorption method, ion exchange method, membrane treatment technology, foam separation technology; chemical treatment methods mainly include flocculation sedimentation, oxidation disinfection; biological treatment methods mainly include nitrification/denitrification, activated sludge method, biological filter, etc. These methods have their own advantages in the treatment of aquaculture wastewater, but there are also certain problems. For example, the biological method can not last for a long time, and its ability to resist adverse environmental impact is poor. Most of the chemical methods need to add additional chemical reagents. Membrane treatment has problems such as high cost, generation of concentrated water, and membrane fouling. Ion exchange and adsorption methods face the problem of adsorbent regeneration. Therefore, it is still necessary to find a ammonia nitrogen, nitrite nitrogen and COD treatment technology with simple process, good treatment effect, small footprint, flexible operation, no secondary pollution and low cost.

Contents of the invention

In order to solve the problems in the background technology, the object of the present invention is to provide a device and method for electrochemically removing ammonia nitrogen, nitrite nitrogen and COD in mariculture wastewater.

In order to achieve the above-mentioned purpose of the invention, the technical scheme adopted in the present invention is:

1. A device for removing ammonia nitrogen, nitrite nitrogen and COD from mariculture wastewater

The invention comprises a water storage tank, a peristaltic pump, an electrochemical reactor and a DC stabilized power supply; the top of the storage tank is provided with a water inlet, the water inlet is connected with the water outlet at the upper end of the electrochemical reactor, and the lower end of the storage tank is provided with a water outlet , the water outlet is connected to the water inlet at the lower end of the electrochemical reactor through a peristaltic pump; the electrochemical reactor is equipped with an anode, a bipolar electrode and a cathode in sequence, the anode is connected to the positive pole of the DC stabilized power supply, and the cathode is connected to the DC stabilized voltage Negative connection of the power supply.

The anode is a platinum electrode, a boron-doped diamond electrode, a titanium-plated titanium-plated ruthenium-plated iridium electrode, a titanium-based iridium-plated electrode or a titanium-based rhodium-plated electrode; the cathode is a graphite electrode, a titanium plate, a boron-doped diamond electrode, a titanium-plated titanium electrode A ruthenium-plated iridium electrode, a titanium-based iridium-plated electrode, or a titanium-based rhodium-plated electrode; the bipolar electrode is a boron-doped diamond electrode or a titanium-plated titanium-plated ruthenium-plated electrode.

The anode, bipolar electrode and cathode of the electrochemical reactor are all circular plate electrodes with the same size.

The anode and the cathode inside the electrochemical reactor are respectively connected to the positive pole and the negative pole of the DC stabilized voltage power supply, and the bipolar electrodes do not need to be connected by wires.

Two, a method for removing ammonia nitrogen, nitrous nitrogen and COD in seawater aquaculture wastewater, the steps of the method are as follows:

Step 1) the wastewater discharged from the mariculture wastewater is collected and enters the reservoir;

Step 2) The outlet water of the reservoir enters the electrochemical reactor equipped with anode, bipolar electrode and cathode through the peristaltic pump, starts the DC stabilized power supply, and the water inlet mode is from the bottom to the top, and the electrodes are placed in parallel to ensure that the electrodes Full and uniform contact with aqueous solution;

Step 3) In the electrochemical reactor, a large amount of Cl ^- in the aqueous solution is oxidized to Cl ₂ at the anode, and the generated Cl ₂ is dissolved in the aqueous solution to generate HOCl, wherein HClO is also ionized to generate ClO ^- ; free chlorine includes Cl ₂ , HOCl and OCl ^- , as strong oxidants, convert ammonia nitrogen into nitrogen, nitrite nitrogen into nitrate nitrogen, and remove COD, that is, complete electrochemical oxidation to remove ammonia nitrogen, nitrite nitrogen and COD in mariculture wastewater.

The mariculture wastewater described in step 1), wherein the concentration of ammonia nitrogen is 0.1-10 mg/L, the concentration of nitrite nitrogen is 0.1-80 mg/L, and the COD is 5-50 mg/L.

The circulation flow in the electrochemical reactor described in step 2) is 1L/min, the current density is 0.5-10mA/cm ² , the plate area is 10-100cm ² , the distance between the plates is 1-5cm, and the hydraulic retention time is 10-40min.

Compared with traditional seawater aquaculture wastewater treatment methods, such as filtration-adsorption method, ion exchange method, membrane treatment technology, activated sludge and biological filter, the beneficial effects of the present invention are:

(1) There is no need to add chemical agents, which can greatly reduce the processing cost;

(2) Free chlorine (Cl2, HClO and ClO-) is continuously generated in situ at the anode, which improves the safety performance;

(3) The treatment process is clean and fast, without generating sludge and secondary pollution;

(4) The removal rate of ammonia nitrogen, nitrite nitrogen and COD is fast and the efficiency is high;

(5) It is only necessary to control the magnitude of the current, which is easy to control;

(6) The device is simple and easy to operate and maintain.

It can be seen that the present invention is a high-efficiency technology for treating ammonia nitrogen, nitrite nitrogen and COD in seawater aquaculture wastewater, and has a good development prospect.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a structural diagram of the electrochemical reactor in the present invention.

Notes in the figure: 1. Reservoir; 2. Peristaltic pump; 3. Electrochemical reactor; 4. DC stabilized power supply; 5. Anode; 6. Cathode; 7. Bipolar electrode.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 1 and Fig. 2, the present invention comprises reservoir 1, peristaltic pump 2, electrochemical reactor 3 and DC stabilized voltage power supply 4; Reservoir 1 top is provided with water inlet, and water inlet and electrochemical reactor 3 The water outlet at the upper end is connected, and the lower end of the reservoir 1 is provided with a water outlet, and the water outlet is connected to the water inlet at the lower end of the electrochemical reactor 3 through the peristaltic pump 2; the electrochemical reactor is equipped with an anode 5, a bipolar The electrode 7 and the cathode 6, the anode 5 is connected to the positive pole of the DC stabilized power supply 4, and the cathode 6 is connected to the negative pole of the DC stabilized voltage power supply 4.

The anode 5 is a platinum electrode, a boron-doped diamond electrode, a titanium-plated titanium-plated ruthenium-plated iridium electrode, a titanium-based iridium-plated electrode or a titanium-based rhodium-plated electrode; the cathode 6 is a graphite electrode, a titanium plate, a boron-doped diamond electrode, a titanium Titanium-plated ruthenium-plated iridium electrode, titanium-based iridium-plated electrode or titanium-based rhodium-plated electrode; the bipolar electrode 7 is a boron-doped diamond electrode or titanium-plated titanium-plated ruthenium-plated iridium electrode.

The anode 5, bipolar electrode 7 and cathode 6 of the electrochemical reactor 3 are all circular plate electrodes with the same size.

The anode 5 and cathode 6 inside the electrochemical reactor 3 are respectively connected to the positive pole and the negative pole of the DC stabilized voltage power supply 4, and the bipolar electrodes 7 do not need to be connected with wires.

Principle of the present invention is:

In a DC electric field, chlorine ions (Cl ^- ) in the water body are oxidized at the anode to generate Cl ₂ , and the generated Cl ₂ is dissolved in the water body to generate HClO, wherein HClO is also ionized to generate ClO ^- , and the reaction equation is as follows:

2Cl ^- →Cl ₂ +2e ^-

Cl ₂ +H ₂ O→HOCl+H ⁺ +Cl ^-

HOCl→H ⁺ +OCl ^-

Because free chlorine (including Cl ₂ , HOCl and OCl ^- ) is a strong oxidant, it can quickly oxidize and remove ammonia nitrogen, nitrite nitrogen and COD in water.

The water bodies to be treated described in each embodiment are all taken from the Muping Marine Farm in Yantai, Shandong. In each embodiment, the initial concentrations of ammonia nitrogen, nitrite nitrogen and COD are respectively controlled within the scope of 0.1-10mg/L, 0.1-80mg/L and 5-50mg/L, covering the range of ammonia nitrogen, nitrite nitrogen and COD in general seawater farms. COD concentration range.

Example 1

Shown in Fig. 1 and Fig. 2, the method for electrochemically removing ammonia nitrogen, nitrite nitrogen and COD in seawater aquaculture wastewater is carried out in the following steps:

1. The wastewater discharged from the mariculture wastewater is collected and enters the reservoir 1;

2. The outlet water of the reservoir 1 enters the electrochemical reactor 3 equipped with the anode 5, the bipolar electrode 7 and the cathode 6 through the peristaltic pump 2, starts the DC stabilized power supply 4, and enters the water from the bottom to the top. The parallel placement of the electrodes can ensure sufficient and uniform contact between the electrodes and the aqueous solution;

3. In the electrochemical reactor 3, a large amount of Cl ^- in the aqueous solution is oxidized to Cl ₂ at the anode, and the generated Cl ₂ is dissolved in the aqueous solution to generate HOCl, wherein HClO is also ionized to generate ClO ^- . Free chlorine (including Cl ₂ , HOCl and OCl ^- ) acts as a strong oxidant to convert ammonia nitrogen into nitrogen gas and nitrite nitrogen into nitrate nitrogen.

And remove COD, that is, complete electrochemical oxidation to remove ammonia nitrogen, nitrite nitrogen and COD in mariculture wastewater.

The anode, cathode and bipolar electrodes are all boron-doped diamond electrodes (purchased from NeoCoat, Switzerland) with an area of 60 cm ² , and the distance between the plates is 1 cm.

The circulating flow rate in the electrochemical reactor 3 is 1 L/min, the hydraulic retention time is 25 min, and the current density is 8 mA/cm ² .

After testing, the concentrations of ammonia nitrogen, nitrite nitrogen and COD before and after treatment are shown in Table 1.

Table 1: Concentrations of typical ammonia nitrogen, nitrite nitrogen and COD before and after treatment (mg/L)

Example 2

Compared with the treatment method in Example 1, the only difference is that the current density is 4mA/cm ² .

After testing, the concentrations of ammonia nitrogen, nitrite nitrogen and COD before and after treatment are shown in Table 2.

Table 2: Concentrations of typical ammonia nitrogen, nitrite nitrogen and COD before and after treatment (mg/L)

Example 3

Compared with Example 1, the treatment method differs only in that the initial concentrations of ammonia nitrogen, nitrite nitrogen and COD are different.

After testing, the concentrations of ammonia nitrogen, nitrite nitrogen and COD before and after treatment are shown in Table 3.

Table 3: Concentrations of typical ammonia nitrogen, nitrite nitrogen and COD before and after treatment (mg/L)

Example 4

Compared with Example 1, the treatment method is only different in that: the anode used in this example is a titanium ruthenium-plated iridium electrode (purchased from Suzhou Borui Industrial Materials Technology Co., Ltd.), and the cathode is a titanium plate (purchased from Suzhou Borui Industrial Materials Technology Co., Ltd.). Industrial Materials Technology Co., Ltd.).

After testing, the concentrations of ammonia nitrogen, nitrite nitrogen and COD before and after treatment are shown in Table 4.

Table 4: Concentrations of typical ammonia nitrogen, nitrite nitrogen and COD before and after treatment (mg/L)

Example 5

Compared with the treatment method in Example 4, the only difference is that the current density is 4mA/cm ² .

After testing, the concentrations of ammonia nitrogen, nitrite nitrogen and COD before and after treatment are shown in Table 5.

Table 5: Concentrations of typical ammonia nitrogen, nitrite nitrogen and COD before and after treatment (mg/L)

Example 6

Compared with Example 4, the treatment method differs only in that the initial concentrations of ammonia nitrogen, nitrite nitrogen and COD are different.

After testing, the concentrations of ammonia nitrogen, nitrite nitrogen and COD before and after treatment are shown in Table 6.

Table 6: Concentrations of typical ammonia nitrogen, nitrite nitrogen and COD before and after treatment (mg/L)

The above-mentioned specific embodiments are used to explain the present invention, rather than to limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modification made to the present invention, equivalent replacement and improvement, etc., all fall into the protection of the present invention. scope.

Claims (7)

1. A device for removing ammonia nitrogen, nitrous nitrogen and COD in seawater aquaculture wastewater, characterized in that it includes a reservoir (1), a peristaltic pump (2), an electrochemical reactor (3) and a DC stabilized power supply ( 4); the top of the reservoir (1) is provided with a water inlet, and the water inlet is connected with the water outlet at the upper end of the electrochemical reactor (3), and the lower end of the reservoir (1) is provided with a water outlet, and the water outlet passes through the peristaltic pump (2 ) is connected to the water inlet at the lower end of the electrochemical reactor (3); the electrochemical reactor is equipped with an anode (5), a bipolar electrode (7) and a cathode (6) in sequence, and the anode (5) is connected to a DC stabilized voltage The positive pole of the power supply (4) is connected, and the cathode (6) is connected with the negative pole of the DC stabilized power supply (4). 2. A device for removing ammonia nitrogen, nitrite nitrogen and COD in seawater aquaculture wastewater according to claim 1, characterized in that: the anode (5) is a platinum electrode, a boron-doped diamond electrode, titanium-plated titanium-plated ruthenium An iridium electrode, a titanium-based iridium-plated electrode or a titanium-based rhodium-plated electrode; Rhodium electrode; the bipolar electrode (7) is a boron-doped diamond electrode or a titanium-plated titanium-plated ruthenium-plated iridium electrode. 3. A device for removing ammonia nitrogen, nitrite nitrogen and COD in seawater aquaculture wastewater according to claim 1, characterized in that: the anode (5) of the electrochemical reactor (3), the bipolar electrode ( 7) and the cathode (6) are circular flat electrodes with the same size. 4. A device for removing ammonia nitrogen, nitrite nitrogen and COD in seawater aquaculture wastewater according to claim 1, characterized in that: the anode (5) and cathode (6) inside the electrochemical reactor (3) They are respectively connected to the positive and negative poles of the DC stabilized voltage power supply (4), and the bipolar electrodes (7) do not need to be connected with wires. 5. be used for the method for removing ammonia nitrogen, nitrous nitrogen and COD in a kind of mariculture wastewater described in claim 1, it is characterized in that, the steps of the method are as follows: Step 1) The wastewater discharged from the mariculture wastewater is collected and enters the reservoir (1); Step 2) The effluent from the reservoir (1) enters the electrochemical reactor (3) equipped with the anode (5), bipolar electrode (7) and cathode (6) through the peristaltic pump (2), and the DC stabilizer is started. Piezoelectric source (4), the way of water inlet is from the bottom to the top, and the electrodes are placed in parallel to ensure sufficient and uniform contact between the electrodes and the aqueous solution; Step 3) In the electrochemical reactor (3), a large amount of Cl ^- in the aqueous solution is oxidized to Cl ₂ at the anode, and the generated Cl ₂ is dissolved in the aqueous solution to generate HOCl, wherein HClO is also ionized to generate ClO ^- ; free chlorine includes Cl ₂ , HOCl and OCl ^- are used as strong oxidants to convert ammonia nitrogen into nitrogen, nitrite nitrogen into nitrate nitrogen, and remove COD, that is, complete electrochemical oxidation to remove ammonia nitrogen, nitrite nitrogen and COD in mariculture wastewater. 6. the method for removing ammonia nitrogen, nitrite nitrogen and COD in a kind of mariculture wastewater according to claim 5, is characterized in that: the mariculture wastewater described in step 1), wherein, ammonia nitrogen concentration 0.1-10mg/L, The concentration of nitrous nitrogen is 0.1-80mg/L, and the COD is 5-50mg/L. 7. The method for removing ammonia nitrogen, nitrite nitrogen and COD in a kind of mariculture wastewater according to claim 5, characterized in that: the circulation flow rate in the electrochemical reactor (3) in step 2) is 1L/min , the current density is 0.5-10mA/cm ² , the plate area is 10-100cm ² , the distance between the plates is 1-5cm, and the hydraulic retention time is 10-40min.