Ammonia nitrogen wastewater electrolysis treatment system and operation method

Abstract

The present invention relates to an ammonia nitrogen wastewater electrolysis treatment system and an operation method. If the reading of the ammonia nitrogen analyzer at the outlet section of the electrolysis reactor is greater than a set value N, and the reading of the residual chlorine concentration meter is less than a set value Y, the preset mode is maintained; otherwise, the opening of the high-concentration ammonia nitrogen wastewater regulating valve is increased. When the reading of the ammonia nitrogen analyzer is less than the set value N or the reading of the residual chlorine concentration meter is less than the set value Y, the reading of the pH meter at the outlet section of the electrolysis reactor is adjusted to be greater than the set value P, and then the high-concentration ammonia nitrogen wastewater regulating valve is adjusted to the reading of the ammonia nitrogen analyzer is less than the set value N and the reading of the residual chlorine concentration meter is greater than the set value N. The beneficial effects of the present invention are: applying control logic, cooperating with an ammonia nitrogen analyzer, a flow meter, a pH meter, a chloride ion concentration meter and a residual chlorine concentration meter, the precise control of the inlet water quality is achieved, the fluctuation of the incoming water quality can be well dealt with, the operation stability of the electrolysis system is improved, and the risk of excessive ammonia nitrogen pollutants in the effluent is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental water treatment, and in particular relates to an ammonia nitrogen wastewater electrolysis treatment system and an operation method. Background Art

[0002] Ammonia nitrogen wastewater is widely derived from the fields of pharmaceuticals, aquaculture, electricity, chemicals, food, medicine, landfill, etc. Removing ammonia nitrogen from water is of great significance to protecting the water environment, reducing the risk of microbial contamination, and improving the safety of drinking water. Common treatment methods for ammonia nitrogen wastewater include air stripping, adsorption, ion exchange, biofilm, activated sludge, electrolysis, etc. Among them, electrolysis has been applied on a large scale in industry due to its advantages of simple operation, rapid reaction, good controllability, no need to add chemicals, and no secondary pollution.

[0003] When treating ammonia nitrogen wastewater by electrolysis, in order to achieve the ideal treatment effect, there are certain requirements for the water quality conditions such as the ammonia nitrogen concentration, chloride ion concentration, pH value, etc. of the influent. The initial ammonia nitrogen wastewater needs to be conditioned before entering the electrolysis reactor for continuous treatment. To achieve this goal, in the existing electrolysis process for treating ammonia nitrogen wastewater, a mixing tank is usually set up to mix multiple water sources and chemical agents in a certain proportion to achieve efficient batch treatment of ammonia nitrogen wastewater. There are three main disadvantages under this process mode: 1) In order to reduce the frequency of ammonia nitrogen wastewater treatment, the mixing tank can usually allow the electrolysis reactor to operate continuously for 5 to 12 hours, resulting in a large volume of the mixing tank. The cost of the mixing tank usually accounts for 20% to 25% of the total equipment cost; 2) The duration of influent conditioning accounts for 40% to 50% of the cycle operation time, which makes the overall efficiency of the ammonia nitrogen wastewater treatment system low; 3) The mixing ratio of different incoming water and the amount of alkali solution added need to be judged by the operating personnel based on experience, and the water quality conditioning effect has a large deviation from the design value; at the same time, due to the large volume of the mixing tank, the uniformity of the mixing of multiple incoming water and the reagent is poor, resulting in large fluctuations in the inlet water quality of the electrolysis reactor and lack of stability in the ammonia nitrogen removal effect.

[0004] In summary, the existing ammonia nitrogen wastewater electrolysis treatment system has the problems of high electrolysis system construction cost, low system operation efficiency and low stability of water quality regulation. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an ammonia nitrogen wastewater electrolysis treatment system and an operation method.

[0006] The ammonia nitrogen wastewater electrolysis treatment system comprises: a low-concentration ammonia nitrogen wastewater pump, a high-concentration ammonia nitrogen wastewater pump, an alkali liquor pump, a pipeline mixer, a filter and an electrolytic reactor; the low-concentration ammonia nitrogen wastewater pump is connected to a low-concentration ammonia nitrogen wastewater regulating valve, the high-concentration ammonia nitrogen wastewater pump is connected to a high-concentration ammonia nitrogen wastewater regulating valve, and both the low-concentration ammonia nitrogen wastewater regulating valve and the high-concentration ammonia nitrogen wastewater regulating valve are connected to the pipeline mixer; the alkali liquor pump is connected to the alkali liquor regulating valve, the alkali liquor regulating valve is connected to the outlet section of the pipeline mixer, the end of the outlet section of the pipeline mixer is connected to the filter, the filter is connected to the electrolytic reactor, and the electrolytic reactor is connected to the water outlet; the inlet end of the filter is provided with a chlorine ion concentration meter, a pH meter, a flow meter and an ammonia nitrogen analyzer; the outlet section of the electrolytic reactor is provided with a pH meter, a residual chlorine concentration meter and an ammonia nitrogen analyzer.

[0007] As a preferred embodiment: the water inlet end of the alkali solution pump is connected to a sodium hydroxide solution with a concentration of 30%.

[0008] The operation method of the ammonia nitrogen wastewater electrolysis treatment system comprises the following steps:

[0009] S1. Confirm the system startup conditions: keep the opening of each regulating valve at 0%, keep the water inlet pump closed, and keep the positions of other valves in the system at the preset state;

[0010] S2. Start the system: start the low-concentration ammonia nitrogen wastewater pump; adjust the opening of the low-concentration ammonia nitrogen wastewater regulating valve until the flow rate of the electrolytic reactor is the system rated flow rate Q;

[0011] S3, reading the readings of each meter, if the reading of the ammonia nitrogen analyzer at the outlet section of the electrolytic reactor is greater than the set value N, and the reading of the residual chlorine concentration meter is less than the set value Y, then maintain the preset mode; otherwise, execute steps S4 to S6;

[0012] S4. Increase the opening of the high-concentration ammonia nitrogen wastewater regulating valve and start the high-concentration ammonia nitrogen wastewater pump;

[0013] S5, reading the readings of each meter, if the reading of the ammonia nitrogen analyzer at the outlet section of the electrolytic reactor is less than the set value N, and the reading of the residual chlorine concentration meter is greater than the set value Y, repeat steps S4 and S5; when the reading of the ammonia nitrogen analyzer is less than the set value N or the reading of the residual chlorine concentration meter is less than the set value Y, execute step S6;

[0014] S6. Adjust the reading of the pH meter at the outlet section of the electrolysis reactor to be greater than the set value P through the alkali solution regulating valve, and then adjust the opening of the high-concentration ammonia nitrogen wastewater regulating valve until the reading of the ammonia nitrogen analyzer is less than the set value N and the reading of the residual chlorine concentration meter is greater than the set value N.

[0015] As a preference: the opening range of a single adjustment of a low-concentration ammonia nitrogen wastewater regulating valve, a high-concentration ammonia nitrogen wastewater regulating valve or an alkali solution regulating valve is 10%.

[0016] Preferably, if the reading of the pH meter at the filter inlet is less than 9.0, the opening of the alkali solution regulating valve is increased until the reading of the pH meter at the filter inlet is 9.0-9.5.

[0017] Preferably, in step S4: while increasing the opening of the high-concentration ammonia nitrogen wastewater regulating valve, the opening of the low-concentration ammonia nitrogen wastewater regulating valve is correspondingly reduced, and the flow meter reading at the inlet end of the electrolysis reactor is kept at the system rated flow Q.

[0018] Preferably, step S6 is specifically as follows: if the reading of the pH meter at the outlet section of the electrolysis reactor is less than or equal to the set value P, the opening of the alkali solution regulating valve is increased until the reading of the pH meter is greater than the set value P; then, if the reading of the ammonia nitrogen analyzer at the outlet section of the electrolysis reactor is greater than the set value N and the reading of the residual chlorine concentration meter is less than the set value Y, the opening of the high-concentration ammonia nitrogen wastewater regulating valve is reduced, and at the same time, the opening of the low-concentration ammonia nitrogen wastewater regulating valve is increased accordingly, and the flow meter reading at the inlet end of the electrolysis reactor is kept at the system rated flow Q, until the reading of the ammonia nitrogen analyzer is less than the set value N and the reading of the residual chlorine concentration meter is greater than the set value N.

[0019] The beneficial effects of the present invention are:

[0020] 1) The ammonia nitrogen wastewater electrolysis treatment system of the present invention adopts a pipeline mixer to replace the mixing tank and its supporting equipment, which improves the mixing effect of ammonia nitrogen wastewater, simplifies the ammonia nitrogen wastewater electrolysis treatment system, and greatly reduces the equipment cost and operation and maintenance cost.

[0021] 2) The present invention evenly mixes different incoming water and alkali solution through a pipeline mixer, thereby realizing rapid conditioning of the inlet water of the electrolytic reactor. The system has a large output range, so that it can process a large amount of high-concentration ammonia nitrogen wastewater according to the system's processing capacity, fully utilize energy, and greatly improve the system operation efficiency.

[0022] 3) The present invention applies control logic, cooperates with ammonia nitrogen analyzer, flow meter, pH meter, chloride ion concentration meter and residual chlorine concentration meter to achieve precise control of inlet water quality, can well cope with fluctuations in incoming water quality, improve the operating stability of the electrolysis system, reduce the risk of excessive ammonia nitrogen pollutants in effluent, and meet the environmental protection needs of users. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of the ammonia nitrogen wastewater electrolysis treatment system of the present invention.

[0024] Explanation of the accompanying drawings: low-concentration ammonia nitrogen wastewater pump 1, high-concentration ammonia nitrogen wastewater pump 2, alkali solution pump 3, low-concentration ammonia nitrogen wastewater regulating valve 4, high-concentration ammonia nitrogen wastewater regulating valve 5, alkali solution regulating valve 6, pipeline mixer 7, filter 8, electrolytic reactor 9, chloride ion concentration meter 10, pH meter 11, flow meter 12, residual chlorine concentration meter 13, ammonia nitrogen analyzer 14. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0026] Embodiment 1

[0027] As an example, Figure 1 As shown, the ammonia nitrogen wastewater electrolysis treatment system includes a low-concentration ammonia nitrogen wastewater pump 1, a high-concentration ammonia nitrogen wastewater pump 2, an alkali solution pump 3, a pipeline mixer 7, a filter 8 and an electrolysis reactor 9.

[0028] The low-concentration ammonia nitrogen wastewater pump 1 is connected to the low-concentration ammonia nitrogen wastewater regulating valve 4, the high-concentration ammonia nitrogen wastewater pump 2 is connected to the high-concentration ammonia nitrogen wastewater regulating valve 5, and the outlet ends of the low-concentration ammonia nitrogen wastewater regulating valve 4 and the high-concentration ammonia nitrogen wastewater regulating valve 5 are both connected to the pipeline mixer 7, and the pipeline mixer 7 automatically mixes the low-concentration ammonia nitrogen wastewater and the high-concentration ammonia nitrogen wastewater; the alkali liquid pump 3 is connected to the alkali liquid regulating valve 6, and the alkali liquid regulating valve 6 is connected to the outlet section of the pipeline mixer 7, so as to adjust the pH value of the wastewater; the end of the outlet section of the pipeline mixer 7 is connected to the filter 8, the filter 8 is connected to the electrolytic reactor 9, and the electrolytic reactor 9 is connected to the water outlet; the inlet end of the filter 8 is provided with a chloride ion concentration meter 10, a pH meter 11, a flow meter 12 and an ammonia nitrogen analyzer 14; the outlet section of the electrolytic reactor 9 is provided with a pH meter 11, a residual chlorine concentration meter 13 and an ammonia nitrogen analyzer 14.

[0029] Among them, the low-concentration ammonia nitrogen wastewater regulating valve 4, the high-concentration ammonia nitrogen wastewater regulating valve 5 and the alkali solution regulating valve 6 are all remotely controlled electric regulating valves, and the low-concentration ammonia nitrogen wastewater pump 1, the high-concentration ammonia nitrogen wastewater pump 2 and the alkali solution pump 3 can be remotely controlled to start and stop.

[0030] The water inlet of the alkali solution pump 3 is connected to a sodium hydroxide solution with a concentration of 30%.

[0031] Embodiment 2

[0032] As another embodiment, this embodiment proposes an operation method of the ammonia nitrogen wastewater electrolysis treatment system proposed in Embodiment 1, which specifically includes the following steps:

[0033] S1. Confirm the system startup conditions: keep the opening of each regulating valve at 0%, keep the water inlet pump closed, and keep the positions of other valves in the system at the preset state;

[0034] S2, start the system: open the low-concentration ammonia nitrogen wastewater regulating valve 4 to 100% opening, start the low-concentration ammonia nitrogen wastewater pump 1; then adjust the flow rate of the electrolytic reactor 9 to the system rated flow rate Q through the low-concentration ammonia nitrogen wastewater regulating valve 4, Q=25t / h;

[0035] S3. After the system is running stably, if the reading of the ammonia nitrogen analyzer 14 at the outlet section of the electrolytic reactor 9 is greater than the set value N, N=15mg / L, and the reading of the residual chlorine concentration meter 13 is less than the set value Y, Y=50mg / L, it means that the water quality of the incoming water has reached the tolerable limit of the system, and it can only be operated in the maximum output mode, and it cannot be further adjusted to achieve the purpose of saving energy consumption, so the preset mode is maintained; otherwise, it means that the concentration of ammonia nitrogen wastewater can be increased, and steps S4 to S6 are executed;

[0036] S4, increase the opening of the high-concentration ammonia nitrogen wastewater regulating valve 5 by 10%, and start the high-concentration ammonia nitrogen wastewater pump 2; increase the concentration of the ammonia nitrogen wastewater entering the electrolytic reactor 9 by one level;

[0037] S5. After the system is running stably, read the readings of each meter. If the reading of the ammonia nitrogen analyzer 14 at the outlet section of the electrolytic reactor 9 is less than the set value N, and the reading of the residual chlorine concentration meter 13 is greater than the set value Y, it means that the ammonia nitrogen wastewater electrolysis treatment system still has room for improvement to treat higher concentration ammonia nitrogen wastewater, then repeat steps S4 and 5, each time increasing the opening of the high-concentration ammonia nitrogen wastewater regulating valve 5 by 10%, and gradually increasing the concentration of ammonia nitrogen wastewater entering the electrolytic reactor 9; when the reading of the ammonia nitrogen analyzer 14 is less than the set value N or the reading of the residual chlorine concentration meter 13 is less than the set value Y, execute step S6.

[0038] S6. The system continues to operate. If the reading of the pH meter 11 at the inlet end of the filter 8 is less than 9.0, the opening of the alkali solution regulating valve 6 is increased to make the reading of the pH meter 11 at the inlet end of the filter 8 9.0-9.5; if the reading of the pH meter 11 at the outlet section of the electrolytic reactor 9 is less than or equal to the set value P, P=6.0, the opening of the alkali solution regulating valve 6 is increased by 10% each time until the reading of the pH meter 11 at the outlet section of the electrolytic reactor 9 reaches the set value P; during operation, if the reading of the ammonia nitrogen analyzer 14 at the outlet section of the electrolytic reactor 9 is greater than the set value N and the reading of the residual chlorine concentration meter 13 is less than the set value Y, it means that the concentration of ammonia nitrogen wastewater at this moment is higher than the treatment range of the system, so the opening of the high-concentration ammonia nitrogen wastewater regulating valve 5 is reduced by 10% each time until the reading of the ammonia nitrogen analyzer 14 is less than the set value N and the reading of the residual chlorine concentration meter 13 is greater than the set value N, so that the system is restored to a state where the concentration of ammonia nitrogen wastewater that can be treated just does not exceed the limit and there is spare capacity.

[0039] Embodiment 3

[0040] In this embodiment, a specific application example of the operation method of the ammonia nitrogen wastewater electrolysis treatment system proposed in Embodiment 2 is given as follows:

[0041] The fine treatment resin regeneration system of a coal-fired power plant produces a large amount of ammonia nitrogen wastewater, with an ammonia nitrogen concentration of 800-1200 mg / L, a chloride ion concentration of about 10000 mg / L, and a pH value of about 9.0. The power plant intends to use electrolysis to treat the ammonia nitrogen wastewater to achieve the standard discharge of ammonia nitrogen (ammonia nitrogen emission limit is 15 mg / L). Because the ammonia nitrogen concentration of the wastewater is too high, the equipment scale is large when directly electrolyzing it, so it is necessary to introduce seawater with low ammonia nitrogen concentration for water quality conditioning. The ammonia nitrogen concentration of seawater at the water intake near the power plant is about 8 mg / L, the chloride ion concentration is about 9000 mg / L, and the pH value is about 8.8; the design is to mix the ammonia nitrogen wastewater of the power plant with seawater in a certain proportion, so that the ammonia nitrogen concentration of the mixed solution is within the range of 80-120 mg / L.

[0042] The power plant applies the ammonia nitrogen wastewater electrolysis treatment system of the present invention, cancels the conventional mixing tank design, and sets a pipeline mixer to directly mix ammonia nitrogen wastewater with high ammonia nitrogen concentration, seawater with low ammonia nitrogen concentration and alkali solution in the water inlet main pipe, realizes inlet water conditioning in the pipeline, and then enters the electrolysis reactor for treatment after the conditioning is completed.

[0043] When the system is running, the seawater is first electrolyzed at an inlet flow rate of 25t / h, and the electrolysis reactor is kept running continuously in a constant voltage mode of 75V. Then the inlet flow rate of ammonia nitrogen wastewater is gradually increased, and the total flow rate is kept unchanged at 25t / h. When the pH value indicated by the pH meter 11 at the inlet end of the filter 8 is lower than 9.0, in order to avoid the system effluent water quality being unqualified within a certain period of time in the initial operation of the system, a small amount of 30% sodium hydroxide solution is added to the inlet water according to experience to control the inlet pH value within the range of 9.0 to 9.5. During continuous operation, the system automatically adjusts the mixing ratio of ammonia nitrogen wastewater and seawater, and the ratio of ammonia nitrogen wastewater to seawater is within the range of 1:15 to 1:7. The ammonia nitrogen concentration of the electrolysis system effluent is kept below 15mg / L, and the residual chlorine concentration is below 100mg / L.

[0044] Since the power plant's ammonia nitrogen wastewater electrolysis treatment system was put into operation six months ago, it has treated a total of 1,800 tons of high-concentration ammonia nitrogen wastewater. The system has been running stably and reliably, and the ammonia nitrogen concentration in the system's effluent has not exceeded the standard. The total system operation time is 690 hours, which is more than 55% shorter than that of the mixing tank electrolysis system. It has greatly reduced the system's operating time and significantly improved its operating efficiency. At the same time, the system's inlet water conditioning is automatically completed according to the preset program, and the inlet water quality meets the design requirements, reducing labor costs while also reducing the risk of operator misoperation.

[0045] The above results show that the ammonia nitrogen wastewater electrolysis treatment system proposed in the present invention has good applicability.

Claims

1. An operating method of an ammonia nitrogen wastewater electrolysis treatment system, characterized in that: The ammonia nitrogen wastewater electrolysis treatment system comprises: a low-concentration ammonia nitrogen wastewater pump (1), a high-concentration ammonia nitrogen wastewater pump (2), an alkali liquid pump (3), a pipeline mixer (7), a filter (8) and an electrolytic reactor (9); the low-concentration ammonia nitrogen wastewater regulating valve (4) and the high-concentration ammonia nitrogen wastewater regulating valve (5) are both connected to the pipeline mixer (7); the alkali liquid regulating valve (6) is connected to the outlet section of the pipeline mixer (7); the end of the outlet section of the pipeline mixer (7) is connected to the filter (8); the filter (8) is connected to the electrolytic reactor (9); and the electrolytic reactor (9) is connected to the water outlet; the inlet end of the filter (8) is provided with a chloride ion concentration meter (10), a pH meter (11), a flow meter (12) and an ammonia nitrogen analyzer (14); the outlet section of the electrolytic reactor (9) is provided with a pH meter (11), a residual chlorine concentration meter (13) and an ammonia nitrogen analyzer (14); the operation method of the ammonia nitrogen wastewater electrolysis treatment system comprises the following steps: S1. Confirm the system startup conditions: keep the opening of each regulating valve at 0%, the water inlet pump closed, and the position of each valve in the preset state; S2, start the system: start the low-concentration ammonia nitrogen wastewater pump (1), and adjust the opening of the low-concentration ammonia nitrogen wastewater regulating valve (4) until the flow rate of the electrolytic reactor (9) reaches the system rated flow rate Q; S3, reading the readings of each meter, if the reading of the ammonia nitrogen analyzer (14) at the outlet section of the electrolytic reactor (9) is greater than the set value N, and the reading of the residual chlorine concentration meter (13) is less than the set value Y, then maintaining the preset mode; otherwise, executing steps S4 to S6; S4, increasing the opening of the high-concentration ammonia nitrogen wastewater regulating valve (5), and starting the high-concentration ammonia nitrogen wastewater pump (2); S5, reading the readings of each meter. If the reading of the ammonia nitrogen analyzer (14) at the outlet section of the electrolytic reactor (9) is less than the set value N, and the reading of the residual chlorine concentration meter (13) is greater than the set value Y, repeating steps S4 and S5; when the reading of the ammonia nitrogen analyzer (14) is less than the set value N or the reading of the residual chlorine concentration meter (13) is less than the set value Y, executing step S6; S6. The pH meter (11) at the outlet of the electrolytic reactor (9) is adjusted to a value greater than the set value P through the alkali solution regulating valve (6), and the opening of the high-concentration ammonia nitrogen wastewater regulating valve (5) is then adjusted until the reading of the ammonia nitrogen analyzer (14) is less than the set value N and the reading of the residual chlorine concentration meter (13) is greater than the set value N.

2. The operating method of the ammonia nitrogen wastewater electrolysis treatment system according to claim 1, characterized in that: The amplitude of the opening of the low-concentration ammonia nitrogen wastewater regulating valve (4), the high-concentration ammonia nitrogen wastewater regulating valve (5) or the alkali solution regulating valve (6) is adjusted once by 10%.

3. The operating method of the ammonia nitrogen wastewater electrolysis treatment system according to claim 1, characterized in that: If the reading of the pH meter (11) at the inlet end of the filter (8) is less than 9.0, the opening of the alkali solution regulating valve (6) is increased until the reading of the pH meter (11) at the inlet end of the filter (8) is 9.0 to 9.

5.

4. The operating method of the ammonia nitrogen wastewater electrolysis treatment system according to claim 1, characterized in that: In step S4: while increasing the opening of the high-concentration ammonia nitrogen wastewater regulating valve (5), the opening of the low-concentration ammonia nitrogen wastewater regulating valve (4) is correspondingly reduced, so that the reading of the flow meter (12) at the inlet end of the electrolytic reactor (9) is maintained at the system rated flow Q.

5. The operating method of the ammonia nitrogen wastewater electrolysis treatment system according to claim 1, characterized in that: Step S6 specifically comprises: if the reading of the pH meter (11) at the outlet section of the electrolytic reactor (9) is less than or equal to the set value P, the opening of the alkali solution regulating valve (6) is increased until the reading of the pH meter (11) is greater than the set value P; then, if the reading of the ammonia nitrogen analyzer (14) at the outlet section of the electrolytic reactor (9) is greater than the set value N and the reading of the residual chlorine concentration meter (13) is less than the set value Y, the opening of the high-concentration ammonia nitrogen wastewater regulating valve (5) is reduced, and at the same time, the opening of the low-concentration ammonia nitrogen wastewater regulating valve (4) is correspondingly increased, and the reading of the flow meter (12) at the inlet end of the electrolytic reactor (9) is maintained at the system rated flow Q, until the reading of the ammonia nitrogen analyzer (14) is less than the set value N and the reading of the residual chlorine concentration meter (13) is greater than the set value N.

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