Acid neutralization biochemical treatment system for wastewater containing dimethylamine

Abstract

The utility model provides a dimethylamine-containing wastewater acid neutralization biochemical treatment system, comprising a dimethylamine wastewater temporary storage system, a wastewater acid neutralization system and a wastewater biochemical treatment system which are arranged in sequence, wherein the dimethylamine wastewater temporary storage system comprises a wastewater storage device, wherein the wastewater storage device is connected to a nitrogen preparation device, and the wastewater acid neutralization system comprises a graphite dilution reactor, wherein the graphite dilution reactor has a first input port and a second input port, wherein the first input port is connected to an output port of the wastewater storage device, wherein the second input port is connected to an output port of a concentrated sulfuric acid storage device, and wherein the output port of the graphite dilution reactor is connected to the wastewater biochemical treatment system. The utility model can overcome the defects in the prior art that dimethylamine gas generated by heating or hydrolysis of dimethylamine wastewater is directly discharged to pollute the air, and the high cost of incineration treatment.

Description

Technical Field

[0001] The utility model relates to the technical field of dimethylamine wastewater treatment, in particular to an acid neutralization biochemical treatment system for dimethylamine-containing wastewater. Background Art

[0002] In the process of recycling dimethylformamide (DMF), the synthetic leather and artificial leather industries will produce wastewater containing DMF. The wastewater contains a large amount of DMF and dimethylamine (DMA) produced by DMF hydrolysis and self-decomposition. Amine wastewater is volatile, irritating and highly toxic, and has a strong carcinogenic effect. my country stipulates that the maximum concentration of DMF allowed to be discharged in surface water is 25 mg / L. The B / C ratio of DMF wastewater is about 0.065, which is difficult to directly biodegrade. Therefore, the treatment of DMF-containing wastewater has attracted widespread attention from domestic and foreign experts.

[0003] The most common method in the market is five-effect distillation, which uses six distillation towers to extract and purify DMF with a concentration of 15% to 25% in the wastewater, and then reuse it in synthetic leather production and resin factories.

[0004] Especially in the DMF distillation recovery process, dimethylamine gas is generated by heating or hydrolysis, and after water washing, a large amount of dimethylamine-containing wastewater is formed and circulated in the system. Although dimethylamine is not very toxic, it has a low boiling point, is volatile, and is easily soluble in water. It has a strong odor that makes people feel unpleasant. Therefore, it is urgent to treat dimethylamine in DMF distillation wastewater from synthetic leather factories. A set of technically feasible and economically reasonable treatment methods must be determined to solve this pollution problem. Utility Model Content

[0005] Therefore, the utility model provides an acid neutralization biochemical treatment system for wastewater containing dimethylamine, which can overcome the defects in the prior art.

[0006] In order to solve the above problems, the utility model provides an acid neutralization biochemical treatment system for dimethylamine-containing wastewater, comprising a dimethylamine wastewater temporary storage system, a wastewater acid neutralization system and a wastewater biochemical treatment system which are arranged in sequence, the dimethylamine wastewater temporary storage system comprising a wastewater storage device, the wastewater storage device being connected to a nitrogen preparation device, the wastewater acid neutralization system comprising a graphite dilution reactor, the graphite dilution reactor having a first input port and a second input port, the first input port being connected to an output port of the wastewater storage device, the second input port being connected to an output port of a concentrated sulfuric acid storage device, and the output port of the graphite dilution reactor being connected to the wastewater biochemical treatment system.

[0007] In some embodiments, the dimethylamine wastewater temporary storage system further includes a tail gas balance unit, and the tail gas balance unit includes an absorption tank, and the absorption tank is also connected to the concentrated sulfuric acid storage device.

[0008] In some embodiments, the absorption tank includes a primary absorption tank and a secondary absorption tank arranged in series.

[0009] In some embodiments, the wastewater biochemical treatment system includes an external carbon source device for adjusting the amount of carbon source required for biological denitrification of the wastewater to be treated.

[0010] In some embodiments, the carbon source provided by the external carbon source device is sodium acetate.

[0011] In some embodiments, the output port of the graphite dilution reactor is also connected to the wastewater storage device, and the wastewater storage device is also connected to the wastewater biochemical treatment system.

[0012] In some embodiments, the volume ratio of the concentrated sulfuric acid and the dimethylamine wastewater flowing into the graphite dilution reactor is 1:0.079, and the mass ratio is 1:0.15.

[0013] In some embodiments, the wastewater acid neutralization system further includes a cooling system, and the cooling system is used to provide cold energy for the graphite dilution reactor.

[0014] In some embodiments, the cooling system includes a first cooling system and a second cooling system arranged in parallel.

[0015] The utility model provides a dimethylamine-containing wastewater acid neutralization biochemical treatment system. The dimethylamine waste gas generated in the distillation and recovery process of synthetic leather DMF-containing wastewater is washed with water and stored in a wastewater storage device. Since the flash point of the wastewater containing 10-15% dimethylamine is low, it is easy to overflow and flash explode. Therefore, a nitrogen seal and tail gas balance unit are used. When the internal pressure of the wastewater storage device is reduced, nitrogen will automatically enter the top of the wastewater storage device under the action of the pressure difference to achieve nitrogen sealing, thereby avoiding the combination of air and dimethylamine gas at the top of the wastewater storage device to produce unsafe accidents. In the wastewater acid neutralization system, combined with the sulfuric acid dosing device used in the DMF distillation process, a graphite dilution reactor is used to react sulfuric acid with dimethylamine-containing wastewater to reduce the dimethylamine content in the wastewater and produce a stable salt solution of dimethylamine sulfate. In the biochemical treatment system, since the B / C and B / N of dimethylamine-containing wastewater are relatively low, in order to improve the biodegradability of the wastewater and enhance the denitrification function, it is necessary to use an external carbon source to adjust the wastewater characteristics and meet the requirements of biochemical degradation of the wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the working principle of the acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to an embodiment of the utility model;

[0017] Figure 2 It is a flow chart of a wastewater biochemical treatment system of a dimethylamine-containing wastewater acid neutralization biochemical treatment system according to an embodiment of the utility model;

[0018] Figure 3 This is a process flow chart of dimethylamine-containing wastewater neutralization in the dimethylamine-containing wastewater acid neutralization biochemical treatment system according to an embodiment of the utility model. DETAILED DESCRIPTION

[0019] See also Figures 1 to 3 As shown, according to an embodiment of the utility model, there is provided a dimethylamine-containing wastewater acid neutralization biochemical treatment system, comprising a dimethylamine wastewater temporary storage system, a wastewater acid neutralization system and a wastewater biochemical treatment system which are arranged in sequence, the dimethylamine wastewater temporary storage system comprising a wastewater storage device, the wastewater storage device being connected to a nitrogen preparation device, the wastewater acid neutralization system comprising a graphite dilution reactor, the graphite dilution reactor having a first input port and a second input port, the first input port being connected to an output port of the wastewater storage device, the second input port being connected to an output port of a concentrated sulfuric acid storage device, and the output port of the graphite dilution reactor being connected to the wastewater biochemical treatment system. During the distillation and recovery process of synthetic leather wastewater containing DMF, the dimethylamine waste gas generated is washed with water and stored in the wastewater storage device. Since the flash point of wastewater containing 10-15% dimethylamine is low, it is easy to overflow and flash explode. Therefore, nitrogen sealing is adopted. When the internal pressure of the wastewater storage device is reduced, nitrogen will automatically enter the top of the wastewater storage device under the action of pressure difference to achieve nitrogen sealing, so as to avoid the combination of air and dimethylamine gas at the top of the wastewater storage device to cause unsafe accidents. In the wastewater acid neutralization system, combined with the sulfuric acid dosing device used in the DMF distillation process, a graphite dilution reactor is used to react sulfuric acid with dimethylamine-containing wastewater to reduce the dimethylamine content in the wastewater and produce a stable salt solution of dimethylamine sulfate.

[0020] In a specific embodiment, the dimethylamine wastewater temporary storage system further includes a tail gas balance unit, the tail gas balance unit includes an absorption tank, and the absorption tank is also connected to the concentrated sulfuric acid storage device. When the pressure of the wastewater storage device increases, the dimethylamine gas enters the absorption tank of the tail gas balance unit and reacts with sulfuric acid to generate sulfate, ensuring that the storage pressure is normal and the dimethylamine gas is not discharged.

[0021] In a specific embodiment, the absorption tank comprises a primary absorption tank and a secondary absorption tank arranged in series. The purpose of arranging two-stage absorption tanks in series is to completely absorb the dimethylamine gas overflowing from the storage tank.

[0022] In a specific embodiment, the wastewater biochemical treatment system includes an external carbon source device for adjusting the carbon source content of the wastewater to be treated. In the biochemical treatment system, since the B / C and B / N of the dimethylamine-containing wastewater are relatively low, in order to improve the biodegradability of the wastewater and enhance the denitrification function, it is necessary to adjust the wastewater characteristics by adding an external carbon source to meet the requirements of biochemical degradation of the wastewater.

[0023] In a specific embodiment, the carbon source provided by the external carbon source device is sodium acetate.

[0024] In a specific embodiment, the output port of the graphite dilution reactor is also connected to the wastewater storage device, and the wastewater storage device is also connected to the wastewater biochemical treatment system. When the concentrated sulfuric acid or the wastewater supply device fails, or its proportion is out of balance, it will cause the problem of increased sulfuric acid concentration in the treated wastewater or incomplete dimethylamine treatment. Because the treated wastewater is returned to the wastewater storage device and mixed with the wastewater before treatment, the excess sulfuric acid is consumed to avoid affecting the subsequent biochemical treatment. When the dimethylamine content of the wastewater storage device is detected to meet the requirements, it is transported as a whole to the wastewater biochemical treatment system for subsequent treatment, which improves the overall operating efficiency of the system and avoids the adverse effects of abnormal treatment on subsequent biochemical treatment.

[0025] In a specific embodiment, the volume ratio of the concentrated sulfuric acid and the dimethylamine wastewater flowing into the graphite dilution reactor is 1:0.079, and the mass ratio is 1:0.15.

[0026] In a specific embodiment, the wastewater acid neutralization system further includes a cooling system, which is used to provide cold energy for the graphite dilution reactor. A large amount of heat is generated during the acid neutralization process, and the cooling system is used to cool the treated wastewater to ensure the normal acid neutralization reaction without generating fogging due to the volatilization of concentrated sulfuric acid.

[0027] In a specific embodiment, the cooling system includes a first cooling system and a second cooling system arranged in parallel. The two cooling systems arranged in parallel can ensure the cooling effect and avoid safety hazards caused by abnormalities in the cooling system to subsequent operations.

[0028] The test was conducted on the treatment of dimethylamine wastewater from a certain factory. The test process and data are as follows:

[0029] The DMF-containing wastewater generated in the synthetic leather process is distilled and recovered by a DMF wastewater low-temperature distillation recovery device, and the remaining dimethylamine wastewater containing 10-15% is stored in a wastewater storage device.

[0030] 1. Small-scale experiment on acid neutralization scheme

[0031] (1) Basic data

[0032] Serial number project Numeric Remark 1 Raw water source Raw water storage tank 2 Raw water dimethylamine concentration 15.4％ On-site measurement 3 Raw water density 0.967g / ml On-site measurement 4 Raw water pH 11.7 On-site measurement 5 Raw water temperature 25℃ On-site measurement 6 Test sulfuric acid concentration 98％ 7 Density of sulfuric acid for testing 1.84g / ml Search information

[0033] (2) Test data

[0034] 2.1. Temperature rise test

[0035] Sulfuric acid was gradually added to the raw water (i.e. dimethylamine wastewater, volume 100 ml) to observe the relationship and trend between the amount of sulfuric acid added and the temperature rise.

[0036] Measuring point Total amount of concentrated sulfuric acid added PH temperature 0 0 11.7 25℃ 1 3.4ml 10.9 47℃ 2 4ml 10.6 48℃ 3 10ml 1.7 67℃

[0037] 2.2 Quantitative test of neutralization reaction

[0038] The mixed liquid produced at the temperature rise test point 3 (raw water volume 100ml, sulfuric acid added 10ml) has a pH value of 1.7 due to excessive acid addition. In order to determine the total amount of sulfuric acid added when the neutralization reaction is complete, raw water is gradually added to the mixed liquid, and the total amount of sulfuric acid added when the pH reaches about 7 is recorded.

[0039]

[0040] 2.3 Escaping material mass determination test

[0041] In the quantitative test of neutralization reaction, steam-like substance overflowed during the titration of sulfuric acid. In order to grasp the mass of the escaping substance, the volume and density of the mixed liquid after the neutralization reaction were measured, and the weight was calculated and then subtracted from the total mass of the original water and sulfuric acid before the neutralization reaction. The difference is the mass of the escaping substance.

[0042] Serial number project Numeric 1 Raw water density 0.967g / ml 2 Raw water volume 126.5ml 3 Raw water quality 122.3255g 4 Volume of sulfuric acid added 10ml 5 98% Sulfuric Acid Density 1.84g / ml 6 Quality of sulfuric acid added 18.4g 7 Total mass of raw water and sulfuric acid before neutralization reaction 140.7255g 8 Volume of mixed solution after neutralization 126ml 9 Total mass of mixed liquid after neutralization 132.22g 10 Mass of escaping matter 8.5055g

[0043] (3) Experimental data analysis

[0044] 3.1. The temperature rise of raw water from the initial state to complete neutralization is about 40℃.

[0045] 3.2. When the concentration of dimethylamine in raw water is 15.4%, 10 ml of 98% concentrated sulfuric acid is required to completely neutralize 126.5 ml of raw water. The volume ratio of raw water to sulfuric acid is 1 to 0.079 (i.e., to treat 1 m 3 Raw water needs to consume 0.079m3 of 98% sulfuric acid 3 ), the dosage ratio is 1 to 0.15 (i.e., 0.15 t of 98% sulfuric acid is required to treat 1 t of raw water).

[0046] 3.3. According to the reaction equation of dimethylamine and sulfuric acid, 1 mol of sulfuric acid can neutralize 2 mol of dimethylamine. Therefore, 0.17 t of 98% concentrated sulfuric acid is required to treat 1 t of 15.4% dimethylamine solution, which is not much different from the test data of 0.15 t. It can be considered that the quantitative test is relatively accurate.

[0047] 3.4. The mass of the steam-like substance escaping during the neutralization reaction is 8.5055 g, accounting for 6% of the total mass of the raw water and the added sulfuric acid before the neutralization reaction.

[0048] 2. Implementation path of acid neutralization solution

[0049] 98% concentrated sulfuric acid enters the graphite dilution reactor through a diaphragm metering pump and undergoes a neutralization reaction with 10% to 15% dimethylamine waste liquid that is transported from the bottom of the storage tank into the graphite dilution reactor through a pump valve. The heat generated is cooled by circulating water to avoid high temperature causing instability in the system.

[0050] The wastewater acid neutralization system includes an acid dosing unit, a wastewater lifting unit and an acid neutralization reaction unit (graphite dilution reactor), and the output end of the wastewater acid neutralization system is connected to the wastewater biochemical treatment system; wherein the dosing unit includes a concentrated sulfuric acid dosing pump and a matching flow meter, which are mainly used to transport concentrated sulfuric acid into the graphite dilution reactor; the wastewater lifting unit includes a lifting water pump and a matching flow meter, which are mainly used to transport dimethylamine-containing wastewater into the graphite dilution reactor; the acid neutralization reaction unit includes a graphite dilution reactor, a pH meter, a flow meter, etc., and is mainly used as a generator for the reaction of concentrated sulfuric acid with dimethylamine-containing wastewater.

[0051] 3. Implementation path of wastewater biochemical treatment program

[0052] According to the B / C and B / N requirements of different wastewater carbon removal and denitrification processes, the wastewater quality is adjusted by adding an external carbon source, and sodium acetate is generally used as the external carbon source.

[0053] Carbon source required for denitrification = (4-CBOD5 / C TN )×C TN / η

[0054] Where: CBOD5 is the influent BOD5 concentration

[0055] C TN Total nitrogen concentration in influent

[0056] η is the BOD5 equivalent of the added carbon source, of which sodium acetate is 0.52

[0057] The wastewater biochemical treatment system includes a pretreatment unit, an external carbon source unit, a biochemical treatment (carbon removal and nitrogen removal process) unit, an advanced oxidation unit, a deep nitrogen removal unit and a matching external carbon source unit. The output end of the wastewater biochemical treatment system is connected to a qualified reuse point. Among them, the pretreatment unit includes but is not limited to a regulating tank, a primary sedimentation tank, etc., which are mainly used to average the amount and quality of wastewater, and remove part of the suspended matter to reduce the impact of the subsequent biochemical treatment unit; the biochemical treatment unit includes but is not limited to A2 / O, oxidation ditch and other biochemical processes with carbon removal and ammonia removal, which mainly remove organic matter, total nitrogen, total phosphorus and other substances in the wastewater; the advanced oxidation unit includes but is not limited to ozone catalytic oxidation, Fenton oxidation and other processes, which are mainly used to further remove organic matter, decolorization and deodorization in the water body; the deep nitrogen removal unit includes but is not limited to denitrification biofilter, biological rotary disc and other processes, which are mainly used to strengthen the removal of total nitrogen, total phosphorus and other substances in the wastewater, and the final discharge water body meets the reuse or discharge requirements. The external carbon source unit includes configuration and dosing devices, which mainly adjust the wastewater quality by adding carbon sources, increase the carbon source content of the wastewater, and provide sufficient carbon sources for denitrification in subsequent biochemical treatment units.

[0058] The above is only a preferred embodiment of the utility model, and is not intended to limit the utility model. Any modifications, equivalent replacements and improvements made within the spirit and principles of the utility model should be included in the protection scope of the utility model. The above is only a preferred implementation of the utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the utility model, and these improvements and variations should also be regarded as the protection scope of the utility model.

Claims

1. A dimethylamine-containing wastewater acid neutralization biochemical treatment system, characterized in that: The invention comprises a dimethylamine wastewater temporary storage system, a wastewater acid neutralization system and a wastewater biochemical treatment system which are arranged in sequence. The dimethylamine wastewater temporary storage system comprises a wastewater storage device which is connected to a nitrogen preparation device. The wastewater acid neutralization system comprises a graphite dilution reactor which has a first input port and a second input port. The first input port is connected to an output port of the wastewater storage device, the second input port is connected to an output port of a concentrated sulfuric acid storage device, and the output port of the graphite dilution reactor is connected to the wastewater biochemical treatment system.

2. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 1, characterized in that: The dimethylamine wastewater temporary storage system further comprises a tail gas balance unit, and the tail gas balance unit comprises an absorption tank, and the absorption tank is also connected to the concentrated sulfuric acid storage device.

3. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 2, characterized in that: The absorption tank comprises a primary absorption tank and a secondary absorption tank which are arranged in series.

4. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 1, characterized in that: The wastewater biochemical treatment system comprises an external carbon source device for adjusting the amount of carbon source required for biological denitrification of the wastewater to be treated.

5. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 4, characterized in that: The carbon source provided by the external carbon source device is sodium acetate.

6. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 1, characterized in that: The output port of the graphite dilution reactor is also connected to the wastewater storage device, and the wastewater storage device is also connected to the wastewater biochemical treatment system.

7. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 1, characterized in that: The volume ratio of the concentrated sulfuric acid and dimethylamine wastewater flowing into the graphite dilution reactor is 1:0.079, and the mass ratio is 1:0.

15.

8. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 1, characterized in that: The wastewater acid neutralization system also includes a cooling system, which is used to provide cold energy for the graphite dilution reactor.

9. The acid neutralization biochemical treatment system for dimethylamine-containing wastewater according to claim 8, characterized in that: The cooling system comprises a first cooling system and a second cooling system which are arranged in parallel.

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