A method and apparatus for treating ammonia-nitrogen water produced in surfactant production

Abstract

The present application belongs to the field of chemical industry, and particularly relates to a treatment method and device for ammonia-nitrogen water generated in surfactant production, comprising the following steps: step 1: ammonia-nitrogen water generated in a surfactant production system is coarsely filtered through a coarse filtration system to remove solid impurities; step 2: the ammonia-nitrogen water is filtered through a primary membrane system, and after filtration, primary concentrated water and primary clean water are obtained; the primary clean water is fed into an intermediate tank; step 3: the primary clean water is filtered through a secondary membrane system, and after filtration, secondary concentrated water and secondary clean water are obtained; the secondary concentrated water is returned to the intermediate tank, and part of the liquid in the intermediate tank is reused to the surfactant production system. The method selects various nanofiltration membranes, and combines production requirements to find a sewage treatment method, in which concentrated liquid can be reused to the production system, and clean water can be discharged to meet the standard; the method can achieve the basic purpose by using only a primary nanofiltration membrane.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical industry, and particularly relates to a treatment method and device for ammonia-nitrogen water generated in surfactant production. BACKGROUND

[0002] Bulk surfactant is an important daily chemical raw material, which is widely used in product fields such as washing and care, and cosmetics as a key functional ingredient, and has high market application value. However, a certain amount of sewage containing ammonia-nitrogen, high COD and total nitrogen value is generated in its production and preparation. If this part of sewage cannot be solved in time and effectively, the accumulation of sewage will cause the production of products to be suspended, which will inevitably cause huge economic losses.

[0003] At present, the methods for treating ammonia-nitrogen water in industry include distillation method, air stripping method, chemical precipitation method, biochemical oxidation method, ion exchange method and the like. Although the above methods can solve the problem of reducing the ammonia-nitrogen value in wastewater in a short period, they have defects such as high energy consumption, low treatment efficiency, large device occupation, and environmental pollution (many by-products) in a long-term treatment cycle.

[0004] In the previous research of the present applicant, we experimented with a variety of nanofiltration membranes to filter such wastewater. Due to the presence of a large amount of small-molecule organic amines in such wastewater, the total nitrogen content in the clean water is high. In order to control the total nitrogen content in the clean water, a multi-stage nanofiltration system must be used for repeated filtration.

[0005] The technical problem to be solved by the present application is: how to use only one nanofiltration membrane to realize the reuse of wastewater raw materials, and control the clean water discharge to be close to or below 100 ppm of total nitrogen. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a treatment method for ammonia-nitrogen water generated in surfactant production. The method selects a nanofiltration membrane in advance, combines the characteristics of organic matter in ammonia-nitrogen wastewater, and combines the production requirements of the surfactant production system. After repeated debugging, a wastewater treatment method capable of producing large amounts of clean water, recycling the concentrated liquid to the production system, and meeting the discharge standard of clean water is found. The method only needs one nanofiltration membrane to achieve the basic purpose.

[0007] Meanwhile, the present application also provides a system suitable for the method.

[0008] In order to achieve the purpose of the present application, the following technical solutions are adopted:

[0009] A treatment method for ammonia-nitrogen water generated in surfactant production, comprising the following steps:

[0010] Step 1: the ammonia-nitrogen water produced by the surfactant production system is coarsely filtered by a coarse filtering system to remove solid impurities in the ammonia-nitrogen water;

[0011] Step 2: the ammonia-nitrogen water is filtered by a primary membrane system, and after the filtration, primary concentrated water and primary clean water are obtained; the primary clean water is fed into an intermediate tank; the pH of the intermediate tank is adjusted to 10±0.5;

[0012] Step 3: the primary clean water is filtered by a secondary membrane system, and after the filtration, secondary concentrated water and secondary clean water are obtained; the secondary concentrated water is returned to the intermediate tank, and part of the liquid in the intermediate tank is reused to the surfactant production system;

[0013] The membrane used by the primary membrane system is a ceramic membrane or a silicon carbide membrane; the membrane used by the secondary membrane system is a polyamide (PA) nanofiltration membrane;

[0014] In Step 2, the membrane inlet pressure is controlled to 0.3-0.4 MPa, and the concentration ratio of the clear liquid and the concentrated liquid is 5-7:1;

[0015] In Step 3, the membrane inlet pressure is controlled to 2.9-3.1 MPa, and the concentration ratio of the clear liquid and the concentrated liquid is 6-9:1.

[0016] After the trial operation, 16 tons of ammonia-nitrogen wastewater can be treated, and 12 tons of clear liquid can be produced;

[0017] After the research, the clear liquid production efficiency is related to the following factors:

[0018] 1. the control of the pH of the intermediate tank;

[0019] 2. the control of the secondary membrane filtration process;

[0020] 3. the selection of the nanofiltration membrane;

[0021] Specifically, the pH of the raw solution is strongly alkaline, and the pH is 11-12; the filtration efficiency of the nanofiltration membrane is the highest under the condition of neutral or slightly acidic, but if it is neutralized to neutral or slightly acidic, the organic bases such as propylenediamine in the ammonia-nitrogen water will be completely neutralized, so that the raw material cannot be reused to the production system; the pH is moderately adjusted to 10±0.5 in the present application, which can optimize the performance of the filtration efficiency, the membrane cleaning cycle, the raw material reusability and the like;

[0022] Taking the raw solution selected in the experimental process as an example, the pH is 11.2-11.8, and the content of propylenediamine is 500-800 mg / L -1 When the pH of the solution is adjusted to 10±0.5, propylenediamine is preferentially neutralized, part of propylenediamine forms chlorinated organic ammonium, and other macromolecular organic amines such as cocamide propyl dimethylamine in the ammonia-nitrogen water are basically not quaternized or a small amount of quaternized under the pH condition.

[0023] The small molecule organic amine is pre-neutralized, and has the following advantages:

[0024] 1. Propylenediamine is a compound with amine groups at both ends. Although the molecular weight is small, when both amine groups are neutralized, the ammonium formed will significantly increase the molecular radius of propylenediamine, making it easier to be adsorbed and intercepted by the nanofiltration membrane. Propylenediamine, as the most likely ammonia nitrogen in wastewater to appear in clean water, can significantly reduce the total nitrogen in clean water. If it is not neutralized to the above pH, but exists in a higher pH form (such as pH 11), the total nitrogen content in the wastewater is difficult to control.

[0025] 2. The polyamide nanofiltration membrane is negatively charged due to the ionization of carboxyl and amino groups (zeta potential is -10~ -50 mV when pH > 3), and it will combine with cationic substances during filtration, so such nanofiltration membranes have a significant advantage in the interception of high-valence metal ions. In the present application, the polyamide nanofiltration membrane and the neutralized propylenediamine are preferentially combined to form a layer of cationic propylenediamine on the surface of the membrane, which is not easy to block the filter holes. It has a longer cleaning cycle. If the ammonia nitrogen water is neutralized to a lower pH value (such as pH 9±0.5), cocamide propyl dimethylamine will be adsorbed by the nanofiltration membrane and accelerate the blockage of the filter holes.

[0026] 3. Moderate pH neutralization can allow the concentrated liquid to be reused in the production system. Under stable working conditions, by returning the concentrated liquid to the intermediate tank, the pH of the liquid in the intermediate tank is maintained at 10±0.5. When reused in the production system, after raw material blending, the pH can be restored to 11~12, maintaining the liquid in the intermediate tank in an optimal concentration state that can be utilized by the production system.

[0027] In addition, in the present application, the concentration ratio needs to be strictly controlled. By controlling the concentration ratio of the nanofiltration membrane, the total nitrogen content in the clear liquid can be controlled to be less than 110 mg / L. When the concentration ratio is less than 6, the efficiency is too low, and when the concentration ratio is greater than 9, the total nitrogen content in the product exceeds the standard.

[0028] In the above treatment method, the flow rate of the intermediate tank reused to the surfactant production system is 0.32~0.75 m³ / h.

[0029] In the above treatment method, the liquid reused from the intermediate tank to the surfactant production system first enters a concentrated liquid tank, and after blending in the concentrated liquid tank, it reaches the application standard required by the surfactant production system.

[0030] The primary concentrated water is returned to the inlet of the coarse filtration system.

[0031] In the above treatment method, the ammonia nitrogen water has a specification of COD: 9000~10000 mg·L -1; total nitrogen: 7500~8500mg·L -1 .

[0032] In the above treatment method, the discharge standard of the secondary clean water is COD≤500mg / L and total nitrogen≤110mg / L.

[0033] Meanwhile, the application also discloses a device for realizing the above method, which comprises a concentrated liquid tank and a wastewater tank, a rough filtration system, a primary membrane system, an intermediate tank and a secondary membrane system connected in sequence; the inlet of the primary membrane system is connected with the outlet of the rough filtration system; the clean liquid outlet of the primary membrane system is connected with the inlet of the intermediate tank; the concentrated liquid outlet of the primary membrane system is connected with the wastewater tank through a first circulating pump; the inlet of the secondary membrane system is connected with the outlet of the intermediate tank; the concentrated liquid outlet of the secondary membrane system is connected with the inlet of the intermediate tank through a second circulating pump; and the outlet of the intermediate tank is connected with the concentrated liquid tank through a first pump.

[0034] In the above device, the inlet of the primary membrane system and the inlet of the secondary membrane system are respectively connected with a feed pump and a booster pump;

[0035] The intermediate tank is provided with a temperature sensor, and the wastewater tank is provided with a liquid level sensor, which is linked with the first circulating pump.

[0036] In the above device, an acid liquid tank is further included, the intermediate tank is provided with a pH sensor, and the clean liquid outlet of the secondary membrane system is connected with a clean water tank through a second pump.

[0037] Compared with the prior art, the application has the following beneficial effects:

[0038] 1. The application can realize the dual purposes of clean liquid discharge and concentrated liquid recycling by using only a primary nanofiltration membrane; and the purposes are realized by controlling the pH of the intermediate tank, selecting the nanofiltration membrane and process control.

[0039] 2. The concentrated water of the application is completely recycled without any concentrated water discharge; the pH of the concentrated water recycled to the production system is 10±0.5, and the pH value required by the system can be restored by mixing with raw material propylene diamine, etc., so that the pH impact on the production system is small and the raw material demand of the production system is completely met. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a flow chart of the ammonia-nitrogen water treatment device of the application. DETAILED DESCRIPTION

[0041] The technical solutions of the application will be further described through specific embodiments. Those skilled in the art should understand that the embodiments are only used to understand the application and should not be regarded as specific limitations on the application.

[0042] Before the method of the present application is described, the ammonia-nitrogen water treatment device of the present application will be described, in particular: with reference to Figure 1 , the ammonia-nitrogen water treatment device of the present application comprises a concentrated liquid tank 12 and a wastewater tank 1, a coarse filtration system 2, a primary membrane system 3, an intermediate tank 4, and a secondary membrane system 5 connected in sequence; the coarse filtration system 2 of the device is selected as a rod filter; the inlet of the primary membrane system 3 is connected with the outlet of the coarse filtration system 2; the clear liquid outlet of the primary membrane system 3 is connected with the inlet of the intermediate tank 4; the concentrated liquid outlet of the primary membrane system 3 is connected with the inlet of the wastewater tank 1 through a first circulating pump 6; the inlet of the secondary membrane system 5 is connected with the outlet of the intermediate tank 4; the concentrated liquid outlet of the secondary membrane system 5 is connected with the inlet of the intermediate tank 4 through a second circulating pump 7; the clear liquid outlet of the secondary membrane system 5 is connected with a second pump 13 and a clean water tank 14; a first pump 8 is arranged between the outlet of the intermediate tank 4 and the concentrated liquid tank 12; the inlet of the primary membrane system 3 and the inlet of the secondary membrane system 5 are respectively connected with a feed pump 9 and a booster pump 10; a temperature sensor is arranged in the intermediate tank 4; a liquid level sensor is arranged in the wastewater tank 1, and the liquid level sensor is linked with the first circulating pump 6. In addition, the device of the present application further comprises an acid liquid tank 11; a pH sensor is arranged in the intermediate tank 4; the outlet of the acid liquid tank 11 is connected with the inlet of the intermediate tank 4 through a pipeline; the acid liquid tank 11 injects acid liquid into the intermediate tank 4 in a pressurized manner; an electromagnetic valve is arranged on the pipeline, and the electromagnetic valve is linked with the pH sensor.

[0043] In production, the system of the present application can be realized by continuous production or intermittent production. If the production is carried out in an intermittent manner, 16 tons of ammonia-nitrogen water is treated in one batch. The subsequent cases are all carried out in an intermittent manner. After each production is completed, the pressure difference before and after the secondary membrane system is detected to determine whether the membrane cleaning is required.

[0044] Example 1

[0045] A treatment method of ammonia-nitrogen wastewater, comprising the following steps:

[0046] Step 1: coarse filtration

[0047] The rod filter is used for coarse filtration, and the water inflow is 16 m 3 / h;

[0048] The COD of the ammonia-nitrogen water is 9726.25 mg·L -1 ; the total nitrogen is 8004.07 mg·L -1 , the pH is 11.4, and the propylene diamine content is 687.34 mg·L -1 ; the subsequent cases all use this water sample for experiment.

[0049] Step 2: primary membrane filtration

[0050] The membrane core assembly of the primary membrane system adopts a 50 nm silicon carbide membrane. The first circulating pump is started. The hand valves before and after the membrane core assembly, the hand valve for discharging the concentrated liquid to the waste water tank, the concentrated liquid backflow adjusting hand valve, the clear liquid sampling hand valve, and the clear liquid discharging hand valve to the intermediate tank are opened.

[0051] The waste water is transported into the primary membrane system. The interlock of the regulating valve and the clear liquid sampling flow meter is put into operation. The membrane inlet pressure is controlled to 0.4 MPa during the filtration process. The concentration ratio (clear liquid: concentrated liquid) is 7:1. When the liquid level of the intermediate tank reaches 1.82 m, the secondary membrane filtration is started.

[0052] Step 3: Secondary membrane filtration

[0053] The pH of the intermediate tank is adjusted to 10±0.5 by hydrochloric acid in the acid tank. The intermediate tank is provided with a temperature control jacket. The water temperature of the intermediate tank is controlled to 45±5℃ by a circulating water pump.

[0054] The feed pump, the hand valves before and after the booster pump, the hand valves before and after the membrane core assembly, the hand valve for discharging the concentrated liquid to the intermediate tank, the concentrated liquid backflow adjusting hand valve, and the clear liquid sampling hand valve are opened. The feed pump and the booster pump are started by the PLC control screen. The waste water is transported into the secondary membrane system. The interlock of the regulating valve and the clear liquid sampling flow meter is put into operation. The membrane inlet pressure is controlled to 3.0 MPa during the filtration process. The concentration ratio (clear liquid: concentrated liquid) is 7:1. The water sample temperature of the intermediate tank is 45±5℃.

[0055] The membrane core assembly of the secondary membrane system adopts a polyamide nanofiltration membrane with a pore size of 1-2 nm.

[0056] After the production is stable, the hand valve for discharging the intermediate tank to the concentrated liquid tank is opened. The liquid in the intermediate tank is pumped into the concentrated liquid tank at a speed of 0.6 m³ / h by the first pump. After the liquid in the concentrated liquid tank is adjusted, it is used as the raw liquid of the surfactant production system. The clear liquid produced by the secondary membrane system can be directly discharged after being detected in the clean water tank.

[0057] Example 2

[0058] A treatment method of ammonia-nitrogen waste water, comprising the following steps:

[0059] Step 1: coarse filtration

[0060] The coarse filtration is performed by using a rod filter. The water inlet flow is 16 m 3 / h.

[0061] Step 2: primary membrane filtration

[0062] The membrane core assembly of the primary membrane system adopts a 50 nm silicon carbide membrane. The first circulating pump is started. The hand valves before and after the membrane core assembly, the hand valve for discharging the concentrated liquid to the waste water tank, the concentrated liquid backflow adjusting hand valve, the clear liquid sampling hand valve, and the clear liquid discharging hand valve to the intermediate tank are opened.

[0063] The wastewater is transported into the primary membrane system, the interlock of the regulating valve and the clean liquid sampling flow meter is put into operation, the membrane pressure is controlled to 0.3 MPa during the filtration process, the concentration ratio (clean liquid: concentrated liquid) is 5:1, and the secondary membrane filtration is started when the liquid level of the intermediate tank reaches 1.65 m.

[0064] Step 3: secondary membrane filtration

[0065] The pH of the intermediate tank is adjusted to 10±0.5 by hydrochloric acid in the acid tank, a temperature control jacket is arranged outside the intermediate tank, and the water temperature of the intermediate tank is controlled to 45±5℃ by a circulating water pump;

[0066] The feed pump, the hand valves before and after the booster pump, the hand valves before and after the membrane core assembly, the hand valve of the concentrated liquid to the intermediate tank, the concentrated liquid backflow regulating hand valve, and the clean liquid sampling hand valve are opened, the feed pump and the booster pump are started by the PLC control screen, the wastewater is transported into the secondary membrane system, the interlock of the regulating valve and the clean liquid sampling flow meter is put into operation, the membrane pressure is controlled to 2.9 MPa during the filtration process, the concentration ratio (clean liquid: concentrated liquid) is 6:1, and the water sample temperature of the intermediate tank is 45±5℃.

[0067] The membrane core assembly of the secondary membrane system is the same as that of Example 1;

[0068] After the production is stable, the hand valve of the intermediate tank to the concentrated liquid tank is opened, the liquid in the intermediate tank is pumped into the concentrated liquid tank at a speed of 0.7 m³ / h by the first pump, and the liquid in the concentrated liquid tank is used as the raw liquid of the surfactant production system after being adjusted; the clean liquid produced by the secondary membrane system can be directly discharged after being detected in the clean water tank.

[0069] Example 3

[0070] A treatment method of ammonia-nitrogen wastewater, comprising the following steps:

[0071] Step 1: coarse filtration;

[0072] A rod filter is used for coarse filtration, and the water inlet flow is 16 m 3 / h.

[0073] Step 2: primary membrane filtration;

[0074] The membrane core assembly of the primary membrane system adopts a 50 nm silicon carbide membrane, the first circulating pump is started, the hand valves before and after the membrane core assembly, the hand valve of the concentrated liquid to the wastewater tank, the concentrated liquid backflow regulating hand valve, the clean liquid sampling hand valve, and the clean liquid hand valve to the intermediate tank are opened;

[0075] The waste water is transported into the primary membrane system, the interlock of the regulating valve and the clean liquid sampling flow meter is put into operation, the membrane pressure is controlled to 0.3-0.4 MPa during the filtration process, the concentration ratio (clean liquid: concentrated liquid) is 6:1, and the secondary membrane filtration is started when the liquid level of the intermediate tank reaches 1.65 m.

[0076] Step 3: secondary membrane filtration;

[0077] The pH of the intermediate tank is adjusted to 10±0.5 by the hydrochloric acid in the acid tank, a temperature control jacket is arranged outside the intermediate tank, and the water temperature of the intermediate tank is controlled to 45±5℃ by the circulating water pump;

[0078] The feed pump, the hand valves before and after the booster pump, the hand valves before and after the membrane core assembly, the hand valve of the concentrated liquid to the intermediate tank, the concentrated liquid backflow regulating hand valve, and the clean liquid sampling hand valve are opened, the feed pump and the booster pump are started by the PLC control screen, the waste water is transported into the secondary membrane system, the interlock of the regulating valve and the clean liquid sampling flow meter is put into operation, the membrane pressure is controlled to 3.1 MPa during the filtration process, the concentration ratio (clean liquid: concentrated liquid) is 9:1, and the water sample temperature of the intermediate tank is 45±5℃.

[0079] The membrane core assembly of the secondary membrane system is the same as that of Example 1;

[0080] After the production is stable, the hand valve of the intermediate tank to the concentrated liquid tank is opened, the liquid in the intermediate tank is pumped into the concentrated liquid tank at a speed of 0.56 m³ / h by the first pump, and the liquid in the concentrated liquid tank is used as the raw liquid of the surfactant production system after being adjusted; the clean liquid produced by the secondary membrane system can be directly discharged after being detected in the clean water tank.

[0081] Comparative Example 1

[0082] The same as Example 1, except that the membrane pressure is controlled to 2.75 MPa during the filtration process, the concentration ratio (clean liquid: concentrated liquid) is 5:1, and the water sample temperature of the intermediate tank is 45±5℃.

[0083] Comparative Example 2

[0084] The same as Example 1, except that the membrane pressure is controlled to 3.2 MPa during the filtration process, the concentration ratio (clean liquid: concentrated liquid) is 12:1, and the water sample temperature of the intermediate tank is 45±5℃.

[0085] Comparative Example 3

[0086] The same as Example 1, except that in Step 3, the pH of the intermediate tank is adjusted to 9±0.5 by the hydrochloric acid.

[0087] Comparative Example 4

[0088] The same as Example 1, except that in Step 3, the pH of the intermediate tank is not adjusted, and the test pH is 11.4.

[0089] Performance detection

[0090] The COD and ammonia nitrogen content of the filtrate after the secondary membrane system filtration were detected, and the detection results are shown in Table 1;

[0091] Table 1 Detection results

[0092] COD / mg L -1 ]] Total nitrogen / mg L -1 ]] Example 1 452 81.51 Example 2 382.6 59.3 Example 3 406.3 107.03 Comparative Example 1 397.9 68.52 Comparative Example 2 605.1 205.43 Comparative Example 3 362.7 43.08 Comparative Example 4 635.7 218.62

[0093] Result analysis:

[0094] 1. It can be seen from Examples 1 to 3 that the total nitrogen of the filtrate is less than 110 mg·L -1 , the COD value is less than 500, and the filtrate approaches or reaches the discharge standard; at the same time, only the pH of the intermediate tank needs to be adjusted to 10±0.5, which can be reused to the production system, without adjusting the pH, and the production system will also be supplemented with raw materials such as propylene diamine, and the pH of the solution in the intermediate tank has almost no impact on the pH stability of the production system.

[0095] 2. It can be seen from Comparative Examples 1 and 2 that too low concentration ratio (Comparative Example 2) can achieve the purpose of reaching the discharge standard, but it reduces the filtrate yield and increases the processing load of the nanofiltration membrane system; too high concentration ratio (Comparative Example 2) cannot achieve the discharge standard of the filtrate.

[0096] 3. It can be seen from Comparative Examples 3 and 4 that a lower pH value is beneficial to the control of total nitrogen and COD value of the filtrate, but based on the system running process, the cleaning cycle of the nanofiltration membrane is 64 tons of ammonia nitrogen water under the running environment of Examples 1 to 3, and the cleaning cycle of the nanofiltration membrane is shortened to 16 tons of ammonia nitrogen water under the running environment of Comparative Example 3 (the cleaning cycle is judged by the pressure difference on both sides of the membrane exceeding 20%); it is explained that the nanofiltration membrane is more prone to blockage when the pH is reduced by about 1. At the same time, a lower pH means that more propylene diamine and other raw materials need to be added when the liquid in the intermediate tank is reused to the production system, which cannot meet the production requirements of matching the appropriate pH and the corresponding appropriate concentration;

[0097] Comparative Example 4 cannot achieve the discharge standard of the filtrate without adjusting the pH, and at least one nanofiltration membrane needs to be additionally added to achieve the purpose of reaching the discharge standard of the filtrate.

[0098] Through analysis, we speculate that the selection of the nanofiltration membrane, the selection of the pH value of the intermediate tank and the setting of the concentration ratio are the key factors to determine the performance of the application. A certain degree of neutralization can ensure that the liquid in the intermediate tank can be reused to the production system, the clear liquid discharge meets the standard, the pre-neutralization pH of the ammonia-nitrogen water is controlled, the propylene diamine is cationized, based on the principle of charge adsorption, the cationized propylene diamine will accumulate on the surface of the nanofiltration membrane, and a layer of adsorption layer is formed on the surface of the nanofiltration membrane, which can block the passage of macromolecular organic matter and avoid the filter hole from being blocked too fast. At the same time, after the amine groups at both ends of the propylene diamine are cationized, the molecular diameter can be increased, and too much propylene diamine can be prevented from being brought into the clear liquid.

[0099] In summary, the selection of the nanofiltration membrane, the concentration ratio and the pH of the intermediate tank are the core factors affecting the realization of the purpose of the application.

[0100] The applicant declares that the process method of the application is illustrated by the above-mentioned embodiments, but the application is not limited to the above-mentioned process steps, and it does not mean that the application must rely on the above-mentioned process steps to be implemented. It should be understood by those skilled in the art that any improvement on the application, equivalent replacement of the raw materials selected by the application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the application.

Claims

1. A method for treating ammonia nitrogen water produced by surfactant production, characterized in that: The steps include: Step 1: The ammonia nitrogen water produced by the surfactant production system is coarsely filtered through a coarse filtration system to remove solid impurities in the ammonia nitrogen water; the ammonia nitrogen water contains no less than 500 mg·L -1 of propylenediamine; Step 2: Filter the ammonia nitrogen water through a primary membrane system to obtain primary concentrated water and primary clean water; the primary clean water enters the intermediate tank, and the pH of the intermediate tank is adjusted to 10±0.5; Step 3: The primary clean water is filtered through a secondary membrane system to obtain secondary concentrated water and secondary clean water. The secondary concentrated water is returned to the intermediate tank, and part of the liquid in the intermediate tank is reused in the surfactant production system. The membrane used in the primary membrane system is a ceramic membrane or a silicon carbide membrane; the membrane used in the secondary membrane system is a polyamide nanofiltration membrane; In step 2, the membrane inlet pressure is controlled to 0.3-0.4 MPa, and the concentration ratio of the clear liquid to the concentrated liquid is 5-7:1; In step 3, the membrane inlet pressure is controlled to 2.9-3.1 MPa, and the concentration ratio of the clear liquid to the concentrated liquid is 6-9:

1.

2. The processing method according to claim 1, characterized in that The flow rate of the intermediate tank recycled to the surfactant production system is 0.32~0.75m³ / h.

3. The processing method according to claim 1, characterized in that The liquid recycled from the intermediate tank to the surfactant production system first enters the concentrate tank and is mixed in the concentrate tank to meet the application standards required by the surfactant production system.

4. The processing method according to claim 1, characterized in that The inlet flow rate of the ammonia nitrogen water is 15~17m 3 / h; the property of the ammonia nitrogen water is COD: 9000~10000mg·L -1 ; Total nitrogen: 7500~8500mg·L -1 .

5. The processing method according to claim 1, characterized in that The discharge standard of the secondary clean water is COD≤500mg / L and total nitrogen≤110mg / L.

6. A device for implementing the method according to any one of claims 1 to 5, characterized in that: It includes a concentrate tank and a wastewater tank, a coarse filtration system, a primary membrane system, an intermediate tank, and a secondary membrane system connected in sequence; the inlet of the primary membrane system is connected to the outlet of the coarse filtration system; the clear liquid outlet of the primary membrane system is connected to the inlet of the intermediate tank; the concentrate outlet of the primary membrane system is connected to the wastewater tank through a first circulation pump; the inlet of the secondary membrane system is connected to the outlet of the intermediate tank; the concentrate outlet of the secondary membrane system is connected to the inlet of the intermediate tank through a second circulation pump; and a first pump is provided between the outlet of the intermediate tank and the concentrate tank.

7. The device according to claim 6, characterized in that The inlet of the primary membrane system and the inlet of the secondary membrane system are respectively connected to a feed pump and a booster pump; A temperature sensor is provided in the intermediate tank; a liquid level sensor is provided in the waste water tank, and the liquid level sensor is linked to the first circulation pump.

8. The device according to claim 6, characterized in that It also includes an acid tank, and a pH sensor is provided in the intermediate tank; the clear liquid outlet of the secondary membrane system is connected to the clear water tank through a second pump.

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