A high-salt ammonia-containing wastewater treatment system and an energy-saving operation process

Abstract

The present invention discloses a high-salt ammonia-containing wastewater treatment system and an energy-saving operation process. The present invention couples a degassing membrane ammonia removal module and an electrochemical oxidation module, and focuses on considering several parameters such as ammonia nitrogen concentration, pH, temperature, energy consumption, and chloride ion concentration to control the process parameters of high-salt ammonia-containing wastewater treatment. The operation process is as follows: set the ammonia nitrogen concentration of the first-stage effluent, calculate the minimum pH value of the influent of the electrochemical oxidation system, then calculate the minimum current of the reactor for the electrochemical oxidation process, so as to calculate the power consumption of the electrochemical oxidation process, calculate the alkali consumption of the degassing membrane system for the degassing membrane ammonia removal process, screen the optimal temperature of the circulating liquid, calculate the heat consumption of the degassing membrane ammonia removal process, calculate the operation duration of the circulating pump, so as to obtain the power consumption, and finally obtain the operation cost. Change the ammonia nitrogen concentration of the effluent, perform exhaustive calculations, and screen to obtain the ammonia nitrogen concentration and other parameters at the minimum cost, and then put it into operation. The control strategy of the present invention effectively realizes the energy-saving operation of the high-salt ammonia-containing wastewater treatment system.

Description

Technical Field

[0001] The present invention belongs to the technical field of ammonia-containing wastewater treatment, and particularly relates to a high-salt ammonia-containing wastewater treatment system and an energy-saving operation process. Background Art

[0002] There are various toxic and harmful substances in industrial wastewater. Among them, nitrogen-containing pollutants entering water bodies are likely to cause eutrophication of water bodies, triggering natural disasters such as water blooms and red tides. After years of research and treatment, most industrial ammonia-containing wastewater has been treated well, but there are still deficiencies in the treatment of high-salt ammonia-containing wastewater.

[0003] The degassing membrane method is a high-salt and high-ammonia-nitrogen wastewater treatment technology. It can separate ammonia nitrogen in wastewater into ammonia gas by adjusting the pH and temperature of the circulating liquid, and then use the absorption liquid to fix the separated ammonia gas. The ammonia removal efficiency of this technology decreases continuously as the ammonia concentration in the circulating liquid decreases. The electrochemical oxidation method is a high-salt and low-ammonia-nitrogen wastewater treatment technology. It can oxidize ammonia nitrogen dissolved in water into nitrogen gas through electrochemical oxidation reactions, thereby achieving complete ammonia removal from wastewater. The total ammonia removal amount of this technology is very limited under the over-current mode. The two high-salt ammonia-containing wastewater treatment technologies have their own characteristics, and there is a possibility of synergistic coupling in the process.

[0004] There are few reports on the deep removal technology of high-salt ammonia-containing wastewater by coupling the degassing membrane method and the electrochemical oxidation method. This is because it is difficult to match the two processes in terms of influent conditions, ammonia nitrogen treatment rate, energy consumption, chemical consumption, etc., and there is a lack of an intelligent control strategy that can balance ammonia nitrogen treatment efficiency and operating cost. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a high-salt ammonia-containing wastewater treatment system and an energy-saving operation process.

[0006] The specific technical solutions are as follows:

[0007] A high-salt ammonia-containing wastewater treatment system includes a degassing membrane ammonia removal module, a conditioning storage tank, and an electrochemical oxidation module;

[0008] The degassing membrane ammonia removal module includes a high-ammonia-nitrogen wastewater collection tank, a lift pump, a security filter, a conditioning water tank, a circulation pump, a PVDF membrane contactor combination, a gas-liquid separator, an ammonia absorption spray tower, an ammonia absorption water tank, and a transfer pump. The high-ammonia-nitrogen wastewater collection tank is sequentially connected to the lift pump, the security filter, and the conditioning water tank. The conditioning water tank, the circulation pump, and the PVDF membrane contactor combination are sequentially connected in a loop. The gas-side outlet of the PVDF membrane contactor combination is sequentially connected to the gas-liquid separator. The gas outlet of the gas-liquid separator is divided into two pipelines. One pipeline is directly connected to the coal-fired power plant denitration system for reuse, and the other pipeline is sequentially connected to the ammonia absorption spray tower, the ammonia absorption water tank, and the transfer pump and then connected to the ammonia addition system of the coal-fired power plant boiler feed water;

[0009] The electrochemically oxidized module includes an electrochemically oxidized reactor, an effluent storage tank, and a cooling water module. The low ammonia nitrogen wastewater outlet of the conditioning water tank is successively connected to a conditioning storage tank, an electrochemically oxidized reactor, an effluent storage tank, and a cooling water module.

[0010] An energy-saving operation process for treating high-salt ammonia-containing wastewater using the above system includes the following steps:

[0011] 1) The high-salt ammonia-containing wastewater in the high ammonia nitrogen wastewater collection tank is transported by a lift pump to a security filter to remove large particulate impurities, and then enters the conditioning water tank.

[0012] 2) The outside of the conditioning water tank is provided with a heat preservation layer. The water temperature is increased by surface heating using low-pressure steam, and the pH value is adjusted using high-concentration liquid caustic soda so that the ammonia nitrogen in the wastewater exists in the form of NH3. The conditioned ammonia-containing wastewater enters a PVDF membrane contactor through a circulation pump. In the PVDF membrane contactor, the volatilized NH3 on the liquid side enters the gas side through gas film diffusion through the transmembrane analysis process, reducing the ammonia partial pressure on the gas side to make the mass transfer process proceed efficiently and continuously. It enters a gas-liquid separator to achieve ammonia-water separation. Part of the separated ammonia gas is directly recycled to the denitrification system of a coal-fired power plant, and the other part of the ammonia gas forms ammonia water through an ammonia absorption spray tower and is recycled to the ammonia addition system for boiler feed water of the coal-fired power plant after passing through an ammonia absorption water tank and a transfer pump.

[0013] 3) The low ammonia nitrogen wastewater obtained after passing through the PVDF membrane contactor re-enters the conditioning water tank. After adjusting the pH, ammonia nitrogen concentration, chloride ion concentration, and conductivity, it enters an electrochemically oxidized reactor to undergo an electrocatalytic oxidation reaction, obtaining an effluent with high residual chlorine and no ammonia nitrogen.

[0014] Further, in step 2), a sodium hydroxide solution with a mass concentration of 30% is used as the high-concentration liquid caustic soda to adjust the pH to 6.0 - 9.0; in step 3), the pH is adjusted to 6.0 - 9.0.

[0015] Further, the control process of process parameters is as follows:

[0016] 1) According to the design parameters, obtain the highest ammonia nitrogen concentration C1 that the electrochemically oxidized reactor can handle, and set the ammonia nitrogen concentration C of the solution actually entering the electrochemically oxidized reactor x , C x ≤C1;

[0017] 2) For each C x value, calculate the minimum energy consumption of the two-stage processes of ammonia removal by the degassing membrane and electrochemically oxidation respectively on the premise of keeping the alkali consumption the lowest.

[0018] 3) For the electrochemically oxidation process, first calculate C xThe total amount of hydrogen ions generated when the ammonia nitrogen in the concentration is completely converted into nitrogen gas. Then, with the pH value of the effluent storage tank being 6.0 - 9.0 as the control value, the minimum value P of the pH of the solution entering the electrochemical oxidation reactor is calculated. x , combined with the chloride ion concentration Cl0, the rated treatment capacity, rated current, and rated voltage of the electrochemical oxidation reactor, the minimum current required when the ammonia nitrogen in the solution completely reacts or the concentration ≤ 1 mg / L is calculated. Then, combined with the rated flow rate of the electrochemical oxidation reactor, the minimum power consumption E2 of the electrochemical oxidation process is deduced.

[0019] 4) For the degassing membrane ammonia removal process, first calculate the alkali consumption A1 for raising the pH of the circulating liquid in the conditioning water tank to Px. Then, measure the heat consumption of low-pressure steam and the circulating duration at complete reaction under different circulating liquid temperatures, so as to deduce the power consumption of the circulating pump. Through software calculation and fitting, find the optimal operating condition to minimize the heat consumption cost and power consumption cost, and record the heat consumption value Q and power consumption value E1 under this optimal operating condition.

[0020] 5) Combining the measurement results of steps 3) and 4), measure the overall power consumption E of the system at Cx value x = E1 + E2, the overall alkali consumption A x = A1, the overall heat consumption Qx = Q. According to the alkali consumption, power consumption, and heat consumption, measure the operating cost R at C x value; x ;

[0021] 6) Use software to calculate and fit R under different C x , compare and select the influent ammonia nitrogen concentration at the lowest operating cost, and combine the optimized operating parameters of steps 3) and 4) for treatment. x The beneficial effects of the present invention are as follows:

[0022] 1) Apply the energy-saving control strategy to optimize and adjust the operating parameters such as the influent water quality, current, voltage, and flow rate of the electrochemical oxidation system, and achieve the energy-saving operation of the electrochemical oxidation system;

[0023] 2) Apply the energy-saving control strategy to optimize and adjust the operating parameters such as the influent water quality, circulating duration, alkali dosage, and steam usage of the degassing membrane system, and achieve the energy-saving operation of the degassing membrane system;

[0024] 3) Deeply couple the operating parameters of the degassing membrane ammonia removal technology and the electrochemical oxidation technology, and can ensure that the effluent ammonia nitrogen concentration is less than 1 mg / L under the lowest energy consumption and the lowest operating cost, which is applicable to the deep treatment and resource recycling of high-salt ammonia-containing wastewater in various application scenarios.

[0025] 3) Deeply couple the operating parameters of the degassing membrane ammonia removal technology and the electrochemical oxidation technology, and can ensure that the effluent ammonia nitrogen concentration is less than 1 mg / L under the lowest energy consumption and the lowest operating cost, which is applicable to the deep treatment and resource recycling of high-salt ammonia-containing wastewater in various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 2 This is the control logic flowchart of the present invention.

[0028] In the figure: 1, quenching storage tank; 2, high ammonia-nitrogen wastewater collection tank; 3, lift pump; 4, security filter; 5, quenching water tank; 6, circulation pump; 7, PVDF membrane contactor; 8, gas-liquid separator; 9, ammonia absorption spray tower; 10, ammonia absorption water tank; 11, transfer pump; 12, electrochemical oxidation reactor; 13, effluent storage tank; 14, cooling water module. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with the specification drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0030] As Figure 1 shown, a high-salt ammonia-containing wastewater treatment system includes a degassing membrane ammonia removal module, a quenching storage tank 1 and an electrochemical oxidation module; the degassing membrane ammonia removal module includes a high ammonia-nitrogen wastewater collection tank 2, a lift pump 3, a security filter 4, a quenching water tank 5, a circulation pump 6, a PVDF membrane contactor combination 7, a gas-liquid separator 8, an ammonia absorption spray tower 9, an ammonia absorption water tank 10 and a transfer pump 11. The high ammonia-nitrogen wastewater collection tank 2 is sequentially connected to the lift pump 3, the security filter 4 and the quenching water tank 5. The quenching water tank 5, the circulation pump 6 and the PVDF membrane contactor combination 7 are sequentially connected in a cycle. The gas-side outlet of the PVDF membrane contactor combination 7 is sequentially connected to the gas-liquid separator 8. The gas outlet of the gas-liquid separator 8 is divided into two pipelines. One pipeline is directly connected to the denitration system of a coal-fired power plant for reuse, and the other pipeline is sequentially connected to the ammonia absorption spray tower 9, the ammonia absorption water tank 10 and the transfer pump 11 and then connected to the ammonia addition system of the boiler feed water of the coal-fired power plant; the electrochemical oxidation module includes an electrochemical oxidation reactor 12, an effluent storage tank 13 and a cooling water module 14. The low ammonia-nitrogen wastewater outlet of the quenching water tank 5 is sequentially connected to the quenching storage tank 1, the electrochemical oxidation reactor 12, the effluent storage tank 13 and the cooling water module 14.

[0031] An energy-saving operation process for treating high-salt ammonia-containing wastewater includes the following steps:

[0032] 1) The high-salt ammonia-containing wastewater in the high ammonia-nitrogen wastewater collection tank 2 is transported by the lift pump 3 to the security filter 4 to filter out large particle impurities, and then enters the quenching water tank 5;

[0033] 2) An insulating layer is provided outside the quenching water tank 5. Low-pressure steam is used to increase the water temperature through surface heating, and high-concentration liquid caustic soda is used to adjust the pH value so that ammonia nitrogen in the wastewater exists in the form of NH3. The ammonia-containing wastewater after quenching enters the PVDF membrane contactor 7 through the circulation pump 6. In the PVDF membrane contactor 7, NH3 volatilized from the liquid side enters the gas side through gas film diffusion through the transmembrane analysis process, reducing the ammonia partial pressure in the gas side to make the mass transfer process proceed efficiently and continuously. Then it enters the gas-liquid separator 8 to achieve ammonia-water separation. Part of the separated ammonia gas is directly recycled to the denitration system of the coal-fired power plant, and the other part of the ammonia gas forms ammonia water through the ammonia absorption spray tower 9 and is recycled to the ammonia addition system of the boiler feed water of the coal-fired power plant after passing through the ammonia absorption water tank 10 and the transfer pump 11;

[0034] 3) The low-ammonia-nitrogen wastewater obtained after passing through the PVDF membrane contactor 7 re-enters the quenching water tank 5. After adjusting the pH, ammonia nitrogen concentration, chloride ion concentration and conductivity, it enters the electrochemical oxidation reactor 12 to carry out electrocatalytic oxidation reaction, and the effluent has high residual chlorine and no ammonia nitrogen.

[0035] As Figure 2 shown, the process parameter control process is as follows:

[0036] 1) According to the design parameters, obtain the highest ammonia nitrogen concentration C1 that the electrochemical oxidation reactor 12 can handle, and set the ammonia nitrogen concentration C x of the solution actually entering the electrochemical oxidation reactor 12, and C x ≤C1;

[0037] 2) For each C x value, calculate the minimum energy consumption of the two processes of degassing membrane ammonia removal and electrochemical oxidation respectively on the premise of keeping the alkali consumption the lowest;

[0038] 3) For the electrochemical oxidation process, first calculate the total amount of hydrogen ions generated when the ammonia nitrogen with a concentration of C x is completely converted into nitrogen gas. Then, taking the pH value of the effluent storage tank 13 as 6.0 - 9.0 as the control value, measure the lowest value P x of the pH of the solution entering the electrochemical oxidation reactor 12. Combine the chloride ion concentration Cl0 and the rated treatment capacity, rated current, and rated voltage of the electrochemical oxidation reactor 12 to measure the minimum current required when the ammonia nitrogen in the solution completely reacts or the concentration ≤ 1mg / L. Then, combine the rated flow rate of the electrochemical oxidation reactor 12 to calculate the minimum power consumption E2 of the electrochemical oxidation process;

[0039] 4) For the degassing membrane deammoniation process, first calculate the alkali consumption A1 to raise the pH of the circulating liquid in the conditioning water tank 1 to Px, then measure the heat consumption of the low-pressure steam and the cycle time for complete reaction at different circulating liquid temperatures, and thus calculate the power consumption of the circulating pump 6. Find the optimal operating condition through software calculation and fitting to minimize the heat consumption cost and power consumption cost, and record the heat consumption value Q and power consumption value E1 under the optimal operating condition;

[0040] 5) Combine the calculation results of step 3) and step 4) to calculate the overall power consumption E of the system under the Cx value. x =E1+E2, overall alkali consumption A x =A1, overall heat consumption Qx=Q, according to alkali consumption, power consumption and heat consumption, calculate C x The running cost R x ;

[0041] 6) Use software to calculate and fit different C x R x , compare and select the influent ammonia nitrogen concentration with the lowest operating cost, and combine it with the optimized operating parameters of step 3) and step 4) for treatment.

[0042] Example

[0043] A coastal coal-fired power plant uses a high-speed mixed bed process to treat condensate. During the resin regeneration process, a large amount of high-salt ammonia-containing wastewater is produced, with an ammonia nitrogen concentration of about 800~1000mg / L and a chloride ion concentration of about 8000~10000mg / L. This wastewater is a regular wastewater and is difficult to treat with conventional processes such as air stripping and biochemical methods.

[0044] By using the system and process of the present invention, the treatment effect of ammonia-containing wastewater is remarkable.

[0045] Among them, the highest ammonia nitrogen concentration that the electrochemical oxidation system can handle is 250 mg / L. On a certain day, the amount of high-salt ammonia-containing wastewater to be treated is 50 t, with an initial ammonia nitrogen concentration of 930 mg / L, an initial pH value of 7.8, an initial temperature of 25 °C, and an initial chloride ion concentration of 10400 mg / L. Before the system runs, the energy-saving operation control strategy is first used to optimize and obtain the best system operation parameters. The specific method is as follows: When calculating that the ammonia nitrogen concentration of the inlet water of the electrochemical oxidation system is 250 mg / L, the lowest pH value of the inlet water of the electrochemical oxidation system is 10.3. At this time, the minimum current of the electrochemical oxidation reactor is 1551 A, the minimum power consumption is 270 kWh, and then it is deduced that the lowest alkali consumption in the circulation water tank is 105 kg of liquid caustic soda. The sum of the heat consumption value and the power consumption value of the degassing membrane system is the lowest under the conditions of 43.5 °C and a circulation duration of 5.6 hours. Calculated at an electricity price of 0.42 yuan / kWh, a steam price of 120 yuan / ton, and a liquid caustic soda price of 900 yuan / ton, the total operating cost is 29.72 yuan / ton of wastewater. Then, using the same method, when calculating that the ammonia nitrogen concentration of the inlet water of the electrochemical oxidation system is 249 mg / L, the operating cost is 29.65 yuan / ton of wastewater, and when calculating that the ammonia nitrogen concentration of the inlet water of the electrochemical oxidation system is 248 mg / L, the operating cost is 29.60 yuan / ton of wastewater. The operating costs at different inlet ammonia nitrogen concentrations are enumerated, and when calculating that the ammonia nitrogen concentration of the inlet water of the electrochemical oxidation system is 100 mg / L, the operating cost is 34.42 yuan / ton of wastewater. After comparison and selection, the lowest operating cost of the system is 29.10 yuan / ton of wastewater. It is deduced that under this working condition, the ammonia nitrogen concentration of the inlet water of the electrochemical oxidation system is 237 mg / L, the inlet water pH value is 10.2, the voltage of the electrochemical oxidation reactor is 50.0 V, the current is 1479 A, the flow rate is 50 t / h, the pH value of the outlet water of the electrochemical oxidation reactor is 6.0, and the ammonia nitrogen concentration is less than 1 mg / L. The temperature of the circulating liquid of the degassing membrane system is 44.6 °C, the circulation duration is 5.5 hours, and the liquid caustic soda dosage is 94 kg. Operating the system with these parameters, the finally measured operating cost is 29.24 yuan / ton of wastewater, which is very close to the calculation result (the error is less than 0.5%), realizing the energy-saving operation of the degassing membrane ammonia removal coupled with the electrochemical oxidation system.

[0046] Since the system was put into operation for one year, its treatment efficiency has been outstanding. In the first-stage degassing membrane process, the circulating liquid operates continuously in a low-temperature and high-pH mode. The temperature of the circulating liquid is controlled within the range of 40 - 45 °C, and the pH value is within the range of 10.0 - 11.0. The real-time control values are automatically determined by the calculation and fitting of the supporting software. The core component of the ammonia stripping module of the degassing membrane is 80 PVDF membrane contactors, which can achieve the separation of ammonia water and recycle ammonia resourcefully to the inlet of the power plant denitrification system. The ammonia nitrogen concentration in the effluent of the ammonia stripping module of the degassing membrane is within the range of 200 mg / L - 250 mg / L, ensuring the effect of deep treatment in the second-stage electrochemical oxidation. When conditioning the effluent of the first stage, there is no need to adjust the pH value additionally, and the temperature reduction range is also very limited (about 9 - 14 °C), saving the overall operation energy consumption of the system. In the second-stage electrochemical oxidation process, the treatment flow rate is about 50 t / h, the voltage of the electrochemical oxidation reactor 12 is 50 V, and the current is within the range of 1278 - 1580 A, which is automatically set by the calculation and fitting of the supporting software. The ammonia nitrogen concentration in the effluent of the electrochemical oxidation reactor 12 is less than 1 mg / L, and the pH is within the range of 6.0 - 9.0. The effluent contains a certain concentration of residual chlorine, which is recycled and used as a circulating water bactericide.

[0047] When the high-salt ammonia-containing wastewater treatment system of this power plant is put into operation, it can operate automatically according to the intelligent control logic. In the case of fluctuating influent water quality, it always maintains the qualified ammonia nitrogen concentration and pH value of the effluent, and operates the system in the most economical way by comprehensively considering the alkali consumption, power consumption and heat consumption. The overall cost of treating high-salt ammonia-containing wastewater is about 25 - 35 yuan per ton, which has significant economic advantages compared with other processes.

Claims

1. An energy-saving operation process for high-salinity ammonia-containing wastewater, characterized in that: The high-salinity ammonia-containing wastewater treatment system used in the process includes a degassing membrane deammoniation module, a conditioning storage tank (1) and an electrochemical oxidation module; The degassing membrane deammonification module comprises a high-ammonia nitrogen wastewater collection pool (2), a lifting pump (3), a safety filter (4), a conditioning water tank (5), a circulation pump (6), a PVDF membrane contactor assembly (7), a gas-liquid separator (8), an ammonia absorption spray tower (9), an ammonia absorption water tank (10) and a delivery pump (11). The high-ammonia nitrogen wastewater collection pool (2) is connected to the lifting pump (3), the safety filter (4) and the conditioning water tank (5) in sequence. The conditioning water tank (5), the circulation pump (6) and the PVDF membrane contactor assembly (7) are connected in a circular manner in sequence. The gas side outlet of the PVDF membrane contactor assembly (7) is connected to the gas-liquid separator (8) in sequence. The gas outlet of the gas-liquid separator (8) is divided into two pipelines, one pipeline is directly connected to the denitration system of the coal-fired power plant for reuse, and the other pipeline is connected to the ammonia absorption spray tower (9), the ammonia absorption water tank (10) and the delivery pump (11) in sequence and then connected to the boiler feed water ammonia adding system of the coal-fired power plant. The electrochemical oxidation module comprises an electrochemical oxidation reactor (12), an outlet water storage tank (13) and a cooling water module (14); the low ammonia nitrogen wastewater outlet of the conditioning water tank (5) is connected to the conditioning storage tank (1), the electrochemical oxidation reactor (12), the outlet water storage tank (13) and the cooling water module (14) in sequence; The process includes the following steps: 1) The high-salt ammonia-containing wastewater in the high-ammonia nitrogen wastewater collection pool (2) is transported to the security filter (4) through the lifting pump (3) to filter out large particle impurities, and then enters the conditioning water tank (5); 2) A heat-insulating layer is provided on the outside of the conditioning water tank (5), and the water temperature is raised by surface heating using low-pressure steam, and the pH value is adjusted by using high-concentration liquid alkali, so that the ammonia nitrogen in the wastewater exists in the form of NH3. The conditioned ammonia-containing wastewater enters the PVDF membrane contactor (7) through the circulation pump (6), and the NH3 volatilized on the liquid side diffuses into the gas side through the gas film through the membrane analysis process in the PVDF membrane contactor (7), thereby reducing the ammonia partial pressure on the gas side so that the mass transfer process is carried out efficiently and continuously, and enters the gas-liquid separator (8) to achieve ammonia-water separation, and part of the separated ammonia gas is directly recycled to the denitration system of the coal-fired power plant, and the other part of the ammonia gas passes through the ammonia absorption spray tower (9) to form ammonia water, and then passes through the ammonia absorption water tank (10) and the delivery pump (11) and is recycled to the coal-fired power plant boiler feed water ammonia addition system; 3) The low ammonia nitrogen wastewater obtained after passing through the PVDF membrane contactor (7) re-enters the conditioning water tank (5), and after adjusting the pH, ammonia nitrogen concentration, chloride ion concentration and conductivity, enters the electrochemical oxidation reactor (12) to undergo an electrocatalytic oxidation reaction, thereby obtaining high residual chlorine and ammonia nitrogen-free effluent; The control process of process parameters is as follows: 1) According to the design parameters, the maximum ammonia nitrogen concentration C1 that the electrochemical oxidation reactor (12) can process is obtained, and the ammonia nitrogen concentration C of the solution actually entering the electrochemical oxidation reactor (12) is set. x , C x ≤C1; 2) For each C x Under the premise of keeping the alkali consumption as low as possible, the minimum energy consumption of the two processes of degassing membrane deammoniation and electrochemical oxidation is calculated respectively; 3) For the electrochemical oxidation process, first calculate C x The total amount of hydrogen ions generated when the concentrated ammonia nitrogen is completely converted into nitrogen gas, and the pH value of the outlet water storage tank (13) is 6.0~9.0 as the control value, and the minimum pH value P of the solution entering the electrochemical oxidation reactor (12) is measured. x , combining the chloride ion concentration Cl0 and the rated processing capacity, rated current and rated voltage of the electrochemical oxidation reactor (12), calculating the minimum current required for the complete reaction of ammonia nitrogen in the solution or when the concentration is ≤1 mg / L, and then calculating the minimum power consumption E2 of the electrochemical oxidation process in combination with the rated flow rate of the electrochemical oxidation reactor (12); 4) For the degassing membrane deammoniation process, first calculate the pH of the circulating liquid in the conditioning water tank (1) to P x The alkali consumption A1 is then calculated, and the heat consumption of low-pressure steam and the cycle time of complete reaction at different circulating liquid temperatures are calculated, thereby calculating the power consumption of the circulating pump (6). The optimal working condition is found through software calculation and fitting, so that the heat consumption cost and the power consumption cost are minimized, and the heat consumption value Q and the power consumption value E1 under the optimal working condition are recorded; 5) Combine the calculation results of step 3) and step 4) to calculate the overall power consumption E of the system under the Cx value. x =E1+E2, overall alkali consumption A x =A1, overall heat consumption Qx=Q, according to alkali consumption, power consumption and heat consumption, calculate C x The running cost R x ; 6) Use software to calculate and fit different C x R x , compare and select the influent ammonia nitrogen concentration with the lowest operating cost, and combine the optimized operating parameters of step 3) and step 4) for treatment; In step 2), a sodium hydroxide solution with a mass concentration of 30% is used as a high concentration liquid alkali, and the pH is adjusted to 6.0-9.0; in step 3), the pH is adjusted to 6.0-9.0.

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