Method and system for treating wastewater with high salinity, high ammonia nitrogen and high chemical oxygen demand

Abstract

The invention provides a method and a system for treating wastewater with high salinity, high ammonia nitrogen and high chemical oxygen demand. The method comprises the step of enabling the wastewater to pass through an oil separation precipitation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological advanced treatment system, a softening turbidity removal treatment system and a multi-stage reverse osmosis concentration treatment system. The method and the system provided by the invention can improve the operation stability and the treatment effect of the wastewater treatment system, and have remarkable energy-saving and environment-friendly benefits.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and particularly to a method and a system for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand. Background Art

[0002] When using conventional treatment processes to treat coking wastewater and semi-coke wastewater, there are problems such as poor biochemical treatment effect, long treatment process, high investment and operation costs, and low operation stability. The core difficulty restricting the biochemical treatment effect of wastewater lies in that the wastewater contains organic molecules that are toxic and inhibitory to microorganisms, resulting in poor biochemical reaction effect and low operation stability of the wastewater treatment system. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies existing in the prior art, and to provide a wastewater treatment process and system for high salt, high ammonia nitrogen and high chemical oxygen demand, which is reasonably designed, meets the national environmental protection requirements, and has low investment and operation costs.

[0004] The technical solution adopted by the present invention to solve the above problems is to propose a method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand.

[0005] The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to the present invention includes passing the wastewater through an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological deep treatment system, a softening and turbidity removal treatment system, and a multi-stage reverse osmosis concentration treatment system. Preferably, the method includes passing the wastewater through the oil separation and sedimentation pretreatment system, the biological detoxification and anaerobic treatment system, the advanced oxidation treatment system, the biological deep treatment system, the softening and turbidity removal treatment system, and the multi-stage reverse osmosis concentration treatment system in sequence. More preferably, the method includes passing the wastewater through the oil separation and sedimentation pretreatment system, the biological detoxification and anaerobic treatment system, the advanced oxidation treatment system, the biological deep treatment system, the softening and turbidity removal treatment system, the multi-stage reverse osmosis concentration treatment system, and a concentrated liquid evaporation and crystallization treatment system in sequence.

[0006] In the method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to the present invention, the oil separation and sedimentation pretreatment system includes equipment such as an adjustment tank, an oil separation tank, oil separation equipment, an oil waste tank, an air flotation oil removal device, a first reagent adding device, a first blower, etc. The wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand is buffered and homogenized in the adjustment tank and then sent to the oil separation tank for static settlement through a supporting transfer pump. The oil separation equipment can separate the oil on the surface of the wastewater in the oil separation tank from the wastewater and send it to the oil waste tank. The wastewater after oil separation treatment enters the air flotation oil removal device through the transfer pump supporting the air flotation oil removal device. The reagent adding device adds reagents such as flocculants (such as polyaluminum chloride, polyferric chloride, polyacrylamide, etc.), acids and alkalis (such as hydrochloric acid, sulfuric acid, sodium hydroxide, lime, etc.), oxidants (such as hydrogen peroxide, sodium hypochlorite, ozone, etc.) to the air flotation oil removal device. The blower blows air into the air flotation oil removal device, and under the action of the stirrer supporting the air flotation oil removal device, the oil and gas floating substances in the wastewater are separated, and the separated waste oil enters the oil waste tank. In an exemplary embodiment according to the present invention, the reagent adding device adds polyaluminum chloride with a concentration of 3% - 5% and polyacrylamide with a concentration of 0.1% - 0.2% to the air flotation oil removal device.

[0007] In the method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to the present invention, the biological detoxification and anaerobic treatment system mainly includes equipment such as a biological detoxification reaction tank, a first sludge return pump, a first sludge tank, an anaerobic reaction tank, a second sludge return pump, etc. The wastewater after air flotation oil removal treatment enters the biological detoxification reaction tank through the transfer pump supporting the biological detoxification reaction tank. Special strains that are salt-tolerant and resistant to toxic molecules such as phenols, anthraquinones, and antibiotics are used to decompose the organic molecules in the biological detoxification reaction tank. The blower blows an appropriate amount of air into the biological detoxification reaction tank. When necessary, a carbon source (such as methanol) and a nitrogen source (such as urea solution) can be added to the biological detoxification reaction tank, and the pH of the wastewater is adjusted to improve the decomposition ability of the strains for organic molecules. The sludge (mainly composed of strains) generated in the biological detoxification reaction tank is returned (returned to the biological detoxification reaction tank) through the first sludge return pump, and the excess sludge enters the sludge tank. The wastewater after detoxification treatment enters the anaerobic reaction tank. Anaerobic biochemical treatment strains are added to the anaerobic reaction tank. Through anaerobic treatment, macromolecular organic substances can be decomposed into small-molecular organic substances. The sludge (mainly composed of strains) generated in the anaerobic reaction tank is returned (returned to the anaerobic reaction tank) through the second sludge return pump, and the excess sludge enters the sludge tank.

[0008] In the method for treating wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, the advanced oxidation treatment system mainly includes equipment such as a Fenton reactor, a second reagent addition device, and a second sludge pool. The wastewater after anaerobic treatment is sent to the Fenton reactor through a supporting delivery pump. The reagent addition device adds reagents such as ferrous sulfate, hydrogen peroxide, and acid (such as hydrochloric acid, sulfuric acid, etc.) to the Fenton reactor, enabling the Fenton reactor to operate at optimal parameters to ensure the best performance in oxidizing and decomposing organic molecules. The sludge generated by the Fenton reactor is discharged to the sludge pool. In an exemplary embodiment according to the present invention, the reagent addition device adds sulfuric acid or hydrochloric acid to the Fenton reactor to adjust the pH of the wastewater in the Fenton reactor to 3 to 5, and then ferrous sulfate and hydrogen peroxide are added successively. The molar ratio of ferrous sulfate to hydrogen peroxide is 1:12 to 1:5.

[0009] In the method for treating wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, the biological advanced treatment system mainly includes equipment such as a membrane aeration bioreactor and a second blower. The wastewater treated by the Fenton reactor enters the membrane aeration bioreactor, and the blower blows an appropriate amount of air into the membrane aeration bioreactor. The membrane aeration bioreactor contains various microbial flora, which can further degrade the organic molecules in the wastewater, significantly reducing the contents of chemical oxygen demand, ammonia nitrogen, etc. in the wastewater. In an exemplary embodiment according to the present invention, the blower blows air into the membrane aeration bioreactor so that the dissolved oxygen content in the wastewater is maintained at 0.2 mg / L to 2 mg / L.

[0010] In the method for treating wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, the softening and turbidity removal treatment system mainly includes equipment such as a tubular microfiltration softening device, a third reagent addition device, and a third sludge pool. The effluent from the membrane aeration bioreactor enters the tubular microfiltration softening device through a supporting delivery pump. The reagent addition device adds reagents such as sodium carbonate and sodium hydroxide to the tubular microfiltration softening device to remove hardness ions such as calcium and magnesium in the wastewater through chemical reactions. The tubular microfiltration softening device can perform microfiltration treatment on the softened wastewater. The generated sludge enters the sludge pool, and the generated filtered water enters the multi-stage reverse osmosis concentration treatment system. In an exemplary embodiment according to the present invention, the reagent addition device adds sodium hydroxide to the tubular microfiltration softening device to adjust the pH to 9.5 to 10.5, and then sodium carbonate is added.

[0011] In the method for treating wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, the multi-stage reverse osmosis concentration treatment system mainly includes equipment such as a multi-stage reverse osmosis concentration device, a fresh water tank, and a concentrated water tank. The multi-stage reverse osmosis concentration device can separate the salts in the wastewater generated by the softening and turbidity removal treatment system to obtain fresh water and concentrated liquid. The fresh water enters the fresh water tank, and the concentrated liquid enters the concentrated water tank. The fresh water in the fresh water tank can be recycled or discharged up to standard. The concentrated liquid can enter the evaporation crystallization treatment system for evaporation crystallization treatment, or the concentrated liquid can be treated by other treatment methods such as electrochemical resource utilization treatment technology. In an exemplary embodiment according to the present invention, the dissolved salt content of the concentrated liquid reaches 8% to 15%.

[0012] In the method for treating wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, the wastewater is further passed through an evaporation crystallization treatment system. Preferably, the wastewater obtained from the multi-stage reverse osmosis concentration treatment system is further passed through an evaporation crystallization treatment system. The evaporation crystallization treatment system mainly includes an evaporation crystallization device, which can evaporate and dry the concentrated liquid. The steam condensate generated enters the fresh water tank for recycling, and the crystal salts generated are sold externally after drying treatment.

[0013] Furthermore, in the method for treating wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, preferably, in the biological detoxification and anaerobic treatment system, the biological detoxification reaction tank uses special strains. The special strains are resistant to a variety of toxic organic molecule, and can decompose organic molecules with toxicity and complex molecular structures into low-toxic or non-toxic organic molecules, facilitating subsequent biological treatment processes such as anaerobic treatment and membrane bioreactor treatment, and improving the biochemical treatment effect of wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand.

[0014] More preferably, in the biological detoxification and anaerobic treatment system, the strains used in the biological detoxification reaction tank include one or more of bacteria of the genus Bacillus and the genus Rhodococcus. In an exemplary embodiment according to the present invention, the strains used in the biological detoxification reaction tank are Bacillus and Rhodococcus mixed at a ratio of 1:1 to 3:1.

[0015] More preferably, in the biological detoxification and anaerobic treatment system, the anaerobic reaction tank uses strains for anaerobic biochemical treatment, and the strains include one or more of methanogens, nitrifying heterotrophic bacteria, and acetic acid bacteria. In an exemplary embodiment according to the present invention, the strains are a mixed strain of methanogens, nitrifying heterotrophic bacteria, and acetic acid bacteria.

[0016] Furthermore, in the method for treating wastewater with high salinity, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, preferably, in the softening and turbidity removal treatment system, a membrane aeration bioreactor is used for advanced biochemical treatment, which has better treatment effects and mass transfer energy-saving effects. The membrane aeration bioreactor can simultaneously have anaerobic - anoxic - aerobic environments, and can efficiently degrade and remove organic molecules in the wastewater, and the effluent quality can meet the inlet requirements of the microfiltration system.

[0017] More preferably, in the softening and turbidity removal treatment system, the membrane aeration bioreactor contains multiple microbial communities, and the multiple microbial communities include one or more of anaerobic ammonium-oxidizing bacteria and aerobic ammonium-oxidizing bacteria. In an exemplary embodiment according to the present invention, the membrane aeration bioreactor contains a mixed strain of anaerobic ammonium-oxidizing bacteria and aerobic ammonium-oxidizing bacteria in a ratio of 1:3 to 1:5.

[0018] Furthermore, in the method for treating wastewater with high salinity, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, preferably, in the multi-stage reverse osmosis concentration treatment system, the multi-stage reverse osmosis concentration device can set different concentration ratios according to the salt content of the wastewater, and finally obtain a concentrated solution with a salt content of not less than 10%, which not only reduces the amount of treated water entering the evaporation and crystallization device subsequently, reduces the wastewater treatment cost, but also recovers fresh water for reuse.

[0019] Furthermore, in the method for treating wastewater with high salinity, high ammonia nitrogen, and high chemical oxygen demand according to the present invention, preferably, in the evaporation and crystallization treatment system, the evaporation and crystallization device can adopt a multi-effect evaporation and crystallization process or a mechanical vapor recompression evaporation and crystallization process, which can be determined after technical and economic comparison according to the site conditions, steam price, electricity cost, etc. of the project.

[0020] The present invention also provides a system for implementing the method according to the present invention, that is, a system for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand, which includes an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological advanced treatment system, a softening and turbidity removal treatment system, and a multi-stage reverse osmosis concentration treatment system. Among them, the oil separation and sedimentation pretreatment system includes an adjustment tank, an oil separation tank, oil separation equipment, a waste oil tank, a flotation oil removal device, a first reagent adding device, and a first blower; the biological detoxification and anaerobic treatment system includes a biological detoxification reaction tank, a first sludge reflux pump, a first sludge tank, an anaerobic reaction tank, and a second sludge reflux pump; the advanced oxidation treatment system includes a Fenton reactor, a second reagent adding device, and a second sludge tank; the biological advanced treatment system includes a membrane aeration biological reactor and a second blower; the softening and turbidity removal treatment system includes a tubular microfiltration softening device, a third reagent adding device, and a third sludge tank; the multi-stage reverse osmosis concentration treatment system includes a multi-stage reverse osmosis concentration device, a fresh water tank, and a concentrated water tank. Preferably, the system includes an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological advanced treatment system, a softening and turbidity removal treatment system, and a multi-stage reverse osmosis concentration treatment system connected in sequence.

[0021] The system according to the present invention further includes an evaporation crystallization treatment system, and the evaporation crystallization treatment system includes an evaporation crystallization device. Preferably, the system includes an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological advanced treatment system, a softening and turbidity removal treatment system, a multi-stage reverse osmosis concentration treatment system, and an evaporation crystallization treatment system connected in sequence.

[0022] Compared with the prior art, the present invention has the following advantages and effects:

[0023] ① The present invention uses strains resistant to toxic molecules such as phenols, anthraquinones, and antibiotics to degrade and treat refractory organic matter molecules in wastewater, reduce the biochemical treatment toxicity of the wastewater, thereby improving the biochemical treatment effect of the wastewater, reducing the cost of wastewater treatment, and improving the operation stability of the wastewater treatment system.

[0024] ② In the present invention, a membrane aeration biological reactor is used for advanced biochemical treatment, which has better treatment effect and mass transfer energy-saving effect, and has significant energy-saving benefits.

[0025] In the present invention, terms such as first, second, and third are used to describe the components of the exemplary embodiments of the present invention, but these terms are only used to distinguish one component from another, and the nature, order, or sequence of the components are not limited by these terms. Description of the Drawings

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention and the prior art, the following will briefly introduce the drawings required for the description of the embodiments and the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 is a schematic diagram of the treatment method and the system used according to the present invention, in which reference numeral 1 represents an adjustment tank, 2 represents an oil separation tank, 3 represents an oil separation device, 4 represents a waste oil tank, 5 represents an air flotation oil removal device, 6 represents a reagent adding device 1, 7 represents a blower 1, 8 represents a biological detoxification reaction tank, 9 represents a sludge reflux pump 1, 10 represents a sludge tank 1, 11 represents an anaerobic reaction tank, 12 represents a sludge reflux pump 2, 13 represents a Fenton reactor, 14 represents a reagent adding device 2, 15 represents a sludge tank 2, 16 represents a membrane aeration biological reactor, 17 represents a blower 2, 18 represents a tubular microfiltration softening device, 19 represents a reagent adding device 3, 20 represents a sludge tank 3, 21 represents a multi-stage reverse osmosis concentration device, 22 represents a fresh water tank, 23 represents a concentrated water tank, and 24 represents an evaporation crystallization device. Specific Embodiments

[0028] The present invention will be further described in detail below with reference to the drawings and through embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0029] Embodiment For Example Figure 1As shown, the method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand of the present invention is implemented using the system of the present invention. Specifically, the wastewater is passed through an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological deep treatment system, a softening and turbidity removal treatment system, a multi-stage reverse osmosis concentration treatment system, and an evaporation crystallization treatment system. The oil separation and sedimentation pretreatment system includes equipment such as an adjustment tank (1), an oil separation tank (2), an oil separation device (3), a waste oil tank (4), a flotation oil removal device (5), a reagent adding device 1 (6), a blower 1 (7), etc. The wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand is buffered and homogenized in the adjustment tank (1) and then sent to the oil separation tank (2) for static settlement through a supporting transfer pump (1-1). The oil separation device (3) can separate the oil on the surface of the wastewater from the wastewater and send it to the waste oil tank (4). The wastewater after oil separation treatment enters the flotation oil removal device (5) through the transfer pump (5-1) supporting the flotation oil removal device (5). The reagent adding device 1 (6) adds polyaluminum chloride with a concentration of 3% - 5% and a concentration of 0.1% - 0.2% polyacrylamide, the blower 1(7) blows air into the air flotation oil removal device (5), and under the action of the stirrer (5-2) supporting the air flotation oil removal device (5), the oil-gas flotation substances in the wastewater are separated, and the separated waste oil enters the waste oil tank (4); the biological detoxification and anaerobic treatment system mainly includes equipment such as a biological detoxification reaction tank (8), a sludge reflux pump 1(9), a sludge tank 1(10), an anaerobic reaction tank (11), a sludge reflux pump 2(12), etc. The wastewater after air flotation oil removal treatment enters the biological detoxification reaction tank (8) through the delivery pump (8-1) supporting the biological detoxification reaction tank (8). Special strains that are salt-tolerant and resistant to toxic molecules such as phenols, anthraquinones, and antibiotics (in this embodiment: a strain mixture of Bacillus and Rhodococcus in a ratio of 1:1) are used. When necessary, a heating device is used to maintain the wastewater temperature at about 35°C to decompose the organic molecules in the biological detoxification reaction tank (8). The blower 1(7) blows an appropriate amount of air into the biological detoxification reaction tank (8). When necessary, a carbon source (methanol) and a nitrogen source (urea solution) can be added to the biological detoxification reaction tank (8), and the wastewater pH is adjusted to about 7 with sulfuric acid or sodium hydroxide solution to improve the decomposition ability of the strains to organic molecules. The sludge (mainly composed of strains) generated in the biological detoxification reaction tank (8) is refluxed (refluxed to the biological detoxification reaction tank) through the sludge reflux pump 1(9), and the excess sludge enters the sludge tank 1(10). The detoxified wastewater enters the anaerobic reaction tank (11). Anaerobic biochemical treatment strains are added to the anaerobic reaction tank (11) (in this embodiment: a mixed strain of methanogens, nitrifying heterotrophs, and acetogens, and their ratio is 1:2:2). When necessary, a heating device is used to maintain the wastewater temperature at about 35°C. Through anaerobic treatment, macromolecular organic substances can be decomposed into small-molecular organic substances. The sludge (mainly composed of strains) generated in the anaerobic reaction tank (11) is refluxed (refluxed to the anaerobic reaction tank) through the sludge reflux pump 2(12), and the excess sludge enters the sludge tank 1(10); the advanced oxidation treatment system mainly includes equipment such as a Fenton reactor (13), a reagent adding device 2(14), a sludge tank 2(15), etc. The wastewater after anaerobic treatment is sent to the Fenton reactor (13) through the supporting delivery pump (13-1). The reagent adding device 2(14) adds reagents such as ferrous sulfate, hydrogen peroxide, and acid to the Fenton reactor (13) (in this embodiment: the wastewater pH in the reactor is adjusted to 4 with sulfuric acid.Around 5, then ferrous sulfate and hydrogen peroxide are added successively, and the molar ratio of ferrous sulfate to hydrogen peroxide is 1:5), so that the Fenton reactor (13) operates at the optimal parameters to ensure the best performance of oxidizing and decomposing organic molecules. The sludge generated by the Fenton reactor (13) is discharged to the sludge tank 2 (15); The biological advanced treatment system mainly includes equipment such as a membrane aeration bioreactor (16) and a blower 2 (17). The wastewater treated by the Fenton reactor (13) enters the membrane aeration bioreactor (16), and the blower 2 (17) blows an appropriate amount of air into the membrane aeration bioreactor (16) (in this embodiment: the dissolved oxygen content in the wastewater is maintained at about 1 mg / L). The membrane aeration bioreactor (16) contains a variety of microbial communities (in this embodiment: a mixed strain of anaerobic ammonia oxidizing bacteria and aerobic ammonia oxidizing bacteria, and their ratio is 1:4), which can further degrade the organic molecules in the wastewater, significantly reducing the content of chemical oxygen demand, ammonia nitrogen, etc. in the wastewater; The softening and turbidity removal treatment system mainly includes equipment such as a tubular microfiltration softening device (18), a reagent adding device 3 (19), and a sludge tank 3 (20). The effluent treated by the membrane aeration bioreactor (16) enters the tubular microfiltration softening device (18) through a supporting transfer pump (18-1). The reagent adding device 3 (19) adds sodium hydroxide to the tubular microfiltration softening device (18) to adjust the pH to about 10.5, and then sodium carbonate is added to remove hardness ions such as calcium and magnesium in the wastewater through a chemical reaction. The tubular microfiltration softening device (18) can perform microfiltration treatment on the softened wastewater, and the generated sludge enters the sludge tank 3 (20), and the generated filtered water enters the multi-stage reverse osmosis concentration treatment system; The multi-stage reverse osmosis concentration treatment system mainly includes equipment such as a multi-stage reverse osmosis concentration device (21), a fresh water tank (22), and a concentrated water tank (23). The multi-stage reverse osmosis concentration device (21) can separate the salts in the wastewater to obtain fresh water and concentrated liquid (in this embodiment: the dissolved salt content reaches 10%). The fresh water enters the fresh water tank (22), and the concentrated liquid enters the concentrated water tank (23). The fresh water in the fresh water tank can be recycled or discharged up to standard, and the concentrated liquid enters the evaporation crystallization treatment system for evaporation crystallization treatment; The evaporation crystallization treatment system mainly includes an evaporation crystallization device (24), which can evaporate and dry the concentrated liquid. The generated steam condensate enters the fresh water tank (22) for recycling, and the generated crystal salt is sold externally after drying treatment.

[0030] During use, the wastewater with high salt, high ammonia nitrogen, and high chemical oxygen demand first enters the regulating tank for buffering to make the water quality uniform, and then enters the oil separation tank for oil separation treatment. After the treatment in the oil separation tank, the wastewater enters the air flotation oil removal device to further remove the oil in the wastewater. The wastewater after air flotation treatment enters the biological detoxification reaction tank for detoxification treatment, significantly reducing the biological toxicity of the wastewater. The effluent from the biological detoxification reaction tank enters the anaerobic tank for anaerobic biochemical treatment to degrade the macromolecular organic matter molecules into small molecules. The wastewater after anaerobic treatment enters the Fenton advanced oxidation treatment device, and the organic matter molecules are further decomposed through advanced oxidation treatment to produce small molecule organic matter that is more easily degraded by microorganisms. After advanced oxidation treatment, the wastewater enters the membrane aerated bioreactor for advanced treatment to further reduce the content of organic molecules in the wastewater. Then, the wastewater enters the tubular microfiltration softening treatment device. After removing impurities such as hardness ions and suspended solids in the water, it enters the multi-stage reverse osmosis concentration treatment device. Under the action of the multi-stage reverse osmosis concentration device, the wastewater is concentrated and reduced in quantity. The generated concentrated liquid enters the evaporation crystallization device for evaporation crystallization treatment, and the generated fresh water is directly recycled or discharged up to the standard.

[0031] Example: The water quality parameters of the semi-coke wastewater generated by a coal chemical enterprise are as follows: chemical oxygen demand 28000 mg / L, ammonia nitrogen content 1500 mg / L, total nitrogen 2200 mg / L, salt content 8500 mg / L, total organic carbon content 12000 mg / L. Using Figure 1 the method and system shown, the chemical oxygen demand in the effluent of the membrane aerated bioreactor is about 160 mg / L, ammonia nitrogen content 50 mg / L, total nitrogen 60 mg / L, salt content 9900 mg / L, total organic carbon content 70 mg / L; the chemical oxygen demand in the effluent of the reverse osmosis device is about 20 mg / L, ammonia nitrogen content 5 mg / L, total nitrogen 6 mg / L, salt content 300 mg / L, total organic carbon content 10 mg / L, and the water quality meets the requirements for discharge up to the standard.

[0032] The foregoing description of the specific exemplary embodiments of the present invention is for the purposes of illustration and exemplification. These descriptions are not intended to be exhaustive of the present invention or to limit the present invention to the precise forms disclosed, and it is obvious that many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical applications, so that other technicians in the art can implement and utilize the various different exemplary embodiments of the present invention, as well as various different selections and changes. The scope of the present invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand, which includes passing the wastewater through an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological deep treatment system, a softening and turbidity removal treatment system, and a multi-stage reverse osmosis concentration treatment system. Among them, The oil separation and sedimentation pretreatment system includes an adjustment tank (1), an oil separation tank (2), an oil separation device (3), a waste oil tank (4), a flotation oil removal device (5), a first reagent adding device (6), and a first blower (7); The biological detoxification and anaerobic treatment system includes a biological detoxification reaction tank (8), a first sludge return pump (9), a first sludge tank (10), an anaerobic reaction tank (11), and a second sludge return pump (12); The advanced oxidation treatment system includes a Fenton reactor (13), a second reagent adding device (14), and a second sludge tank (15); The biological advanced treatment system includes a membrane aeration bioreactor (16) and a second blower (17); The softening and turbidity removal treatment system includes a tubular microfiltration softening device (18), a third reagent adding device (19), and a third sludge tank (20); The multi-stage reverse osmosis concentration treatment system includes a multi-stage reverse osmosis concentration device (21), a fresh water tank (22), and a concentrated water tank (23).

2. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 1, characterized in that The biological detoxification reaction tank (8) uses strains resistant to toxic organic molecule to decompose the toxic organic molecules into low-toxic or non-toxic organic molecules.

3. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 2, characterized in that The strains used in the biological detoxification reaction tank (8) include one or more of bacteria of the genus Bacillus and the genus Rhodococcus.

4. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 1, characterized in that The anaerobic reaction tank (11) uses strains for anaerobic biochemical treatment, and the strains include one or more of methanogens, nitrifying heterotrophs, and acetic acid bacteria.

5. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 1, characterized in that The membrane aeration bioreactor (16) performs advanced biochemical treatment and contains a variety of microbial flora, and the variety of microbial flora includes one or more of anaerobic ammonia oxidizing bacteria and aerobic ammonia oxidizing bacteria.

6. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 1, characterized in that The multi-stage reverse osmosis concentration device (21) can set different concentration ratios according to the salt content of the wastewater, and finally obtain a concentrated liquid with a salt content of not less than 10%.

7. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 1, characterized in that The method includes subjecting the wastewater to an evaporation and crystallization treatment system, and the evaporation and crystallization treatment system includes an evaporation and crystallization device (24).

8. The method for treating wastewater with high salt, high ammonia nitrogen and high chemical oxygen demand according to claim 7, characterized in that The evaporation and crystallization device (24) adopts a multi-effect evaporation and crystallization process or a mechanical vapor recompression evaporation and crystallization process.

9. A system for the method according to any one of claims 1 to 8, which includes an oil separation and sedimentation pretreatment system, a biological detoxification and anaerobic treatment system, an advanced oxidation treatment system, a biological deep treatment system, a softening and turbidity removal treatment system, and a multi-stage reverse osmosis concentration treatment system. Among them, The oil separation and sedimentation pretreatment system includes an adjustment tank (1), an oil separation tank (2), an oil separation device (3), a waste oil tank (4), a flotation oil removal device (5), a first reagent adding device (6), and a first blower (7); The biological detoxification and anaerobic treatment system includes a biological detoxification reaction tank (8), a first sludge return pump (9), a first sludge tank (10), an anaerobic reaction tank (11), and a second sludge return pump (12); The advanced oxidation treatment system includes a Fenton reactor (13), a second reagent adding device (14), and a second sludge tank (15); The biological advanced treatment system includes a membrane aeration bioreactor (16) and a second blower (17); The softening and turbidity removal treatment system includes a tubular microfiltration softening device (18), a third reagent adding device (19), and a third sludge tank (20); The multi-stage reverse osmosis concentration treatment system includes a multi-stage reverse osmosis concentration device (21), a fresh water tank (22), and a concentrated water tank (23).

10. The system according to claim 9, further comprising an evaporation crystallization treatment system, wherein the evaporation crystallization treatment system includes an evaporation crystallization device (24).

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