Method and system for treating waste liquid containing salt and organic matters

Abstract

The invention belongs to the field of treatment of salt-containing organic waste liquid, and particularly relates to a treatment method and system for waste liquid containing salt and organic matter, the method comprises the following steps: filtering the waste liquid containing salt and organic matter, diluting with water to obtain waste liquid to be oxidized with the salt content controlled below 5wt%, and then carrying out oxidation reaction to obtain the waste liquid containing salt and organic matter. Waste liquid containing water-soluble organic acid salt is obtained; wherein inorganic alkali liquor is added, so that the pH value of the waste liquid to be oxidized in the step (3) is 10-13; the waste liquid containing the water-soluble organic salt is divided into two streams, the first stream is subjected to electrodialysis to obtain three streams of materials, namely an inorganic alkali aqueous solution, an organic acid aqueous solution and desalted water, and the inorganic alkali aqueous solution serves as a raw material of the previous treatment stage; and the second stream is mixed with at least part of the organic acid aqueous solution to enable the pH to be 6.5-7.5, and optionally mixed with the desalted water to obtain the treated biochemical waste liquid. According to the invention, the alcohol-containing and salt-containing waste liquid with extremely low biodegradability is changed into sewage with good biodegradability by adopting a simple method, and an unexpected technical effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of treatment of saline organic waste liquid, and specifically relates to a method and system for treating waste liquid containing salt and organic matter. Background Technology

[0002] In the production process of chemical products, waste liquids containing high salt content and oligohydric alcohols may be generated. For example, byproducts of certain chemical reactions, residues from incomplete reactions, or waste from the bottom of refining towers during product purification.

[0003] Water-soluble organic wastewater containing high salt content and oligohydric alcohols differs from common wastewater containing salt and organic matter. Common wastewater containing salt and organic matter typically has a TDS (total dissolved solids) of around 5000 mg / L, while water-soluble organic wastewater containing high salt content and oligohydric alcohols (the raw material or object of treatment in the treatment method of this invention) has a very low water content, generally <10 wt%, and a salt content of 10-30 wt%, with the remainder being organic matter. Therefore, existing methods for treating wastewater containing salt and organic matter are not suitable for the raw material of this invention.

[0004] Water-soluble organic waste liquids containing high salt content and oligohydric alcohols need to be treated as hazardous waste. The conventional hazardous waste disposal method is incineration, but there are several problems with the incineration of such substances:

[0005] Problem 1: It contains a high amount of inorganic salts, so inorganic salts tend to accumulate at the furnace mouth during incineration, causing damage to the furnace nozzle, or a large amount of ash will be produced, resulting in a high frequency of filter bag replacement and unstable operation of the equipment.

[0006] Question 2: It contains a lot of moisture, has a low calorific value, and requires the use of natural gas to assist combustion.

[0007] Question 3: It has biotoxicity, B5 / C ​​< 0.3, and poor biochemical properties. Summary of the Invention

[0008] To address the technical problems of existing methods for treating water-soluble organic wastewater containing high salinity and oligohydric alcohols, this invention provides a method for treating wastewater containing salt and organic matter. This invention uses ozone as an oxidant and employs a multi-step treatment process to degrade oligohydric alcohols in the organic wastewater, primarily in an alcohol-containing aqueous solution. This process degrades the difficult-to-biodegrade oligomers into smaller organic molecules, thereby improving biodegradability and transforming the difficult-to-biodegrade organic wastewater into easily treatable industrial wastewater, while also eliminating COD. Furthermore, this invention can convert the inorganic salts in the wastewater into other process materials for recycling within the system, reducing salt emissions. The organic acids produced by ozone are excellent carbon sources for biological systems. This invention uses a simple method to transform alcohol- and salt-containing wastewater with extremely low biodegradability into highly biodegradable wastewater, achieving unexpected technical results.

[0009] Compared to combustion, this invention operates stably and does not have problems such as burner damage. Furthermore, this invention uses electrically driven equipment, and if the electricity source is green electricity in the future, the process will be a green and low-carbon process. Compared to wet oxidation, this invention has lower temperature and lower pressure, so it does not require a pressure vessel, has good safety, fewer equipment requirements, and lower investment costs.

[0010] To achieve the above-mentioned invention, a first aspect of the present invention is to provide a method for treating wastewater containing salt and organic matter, wherein the organic matter is one or more of organic alcohols and oligomers with a degree of polymerization of less than 20; comprising:

[0011] (1) The waste liquid containing salt and organic matter is filtered to obtain waste liquid with insoluble particulate matter removed;

[0012] (2) The waste liquid obtained in step (1) is optionally diluted with water to obtain a waste liquid to be oxidized with the salt content controlled below 5 wt%.

[0013] (3) The waste liquid to be oxidized is contacted with ozone to carry out an oxidation reaction, and a waste liquid containing water-soluble organic acid salts is obtained, which is industrial wastewater containing organic salts with good biodegradability;

[0014] In this process, an inorganic alkaline solution is added before step (1), or in one or more steps of step (1) or step (3) so that the pH of the waste liquid to be oxidized in step (3) is 10 to 13.

[0015] (4) The waste liquid containing water-soluble organic salts is divided into two streams. The first stream of waste liquid containing water-soluble organic salts is subjected to electrodialysis to obtain three materials: inorganic alkali aqueous solution, organic acid aqueous solution, and desalinated water. The inorganic alkali aqueous solution is used as the raw material for obtaining the inorganic alkali solution used to oxidize the waste liquid. That is, it is returned to one or more steps before step (1), step (1), or step (3) as inorganic alkali solution, so that the pH of the waste liquid to be oxidized in step (3) is 10 to 13.

[0016] (5) The second stream of waste liquid containing water-soluble organic salts is combined with at least part of the obtained aqueous organic acid solution to make the pH 6.5 to 7.5, and optionally combined with the demineralized water to obtain the treated biodegradable waste liquid.

[0017] As described in the background section, the raw materials in this invention have a very low water content (<10 wt%) and a salt content of 10–30 wt%. Even if diluted with water as in step (2) to obtain a waste liquid to be oxidized with a salt content controlled below 5 wt%, the minimum concentration of organic matter is approximately 6 wt%. Even after dilution, it still belongs to high-concentration organic wastewater, which is different from conventional organic wastewater with a COD value not exceeding 1000 mg / L, i.e., 0.1 wt%.

[0018] As previously mentioned, an inorganic alkali solution is added before step (1), or in one or more steps of step (1) or (2) to make the pH of the waste liquid to be oxidized in step (2) 10-13. The role of the inorganic alkali solution is as a reaction aid, catalyzing the reaction between the organic matter in the waste liquid to be oxidized and ozone. That is, in the presence of the inorganic alkali, the organic matter in the waste liquid of the present invention reacts with ozone to obtain organic acid salts.

[0019] The pH of the waste liquid to be oxidized is controlled at 10-13 to ensure that the amount of inorganic alkali used is optimal for catalytic and ozone reactions. The amount of inorganic alkali directly affects the efficiency of alcohol to organic salt conversion. When the degree of polymerization of the organic alcohol is high, insufficient alkali will not effectively break the chain, and the polymer will have a significant impact on the B / C ratio, thus failing to achieve the desired effect.

[0020] In this invention, the filtration in step (1) is not for removing heavy components or heavy metal ions such as Ca+, but rather serves as a protective unit to prevent iron filings from the raw materials caused by corrosion of the process equipment, or organic alcohols from becoming insoluble due to excessive polymerization at the end of the previous process, from damaging the subsequent membrane system or affecting the reactor itself.

[0021] According to the present invention, the salt content in the waste liquid to be oxidized needs to be controlled below 5 wt% because, based on extensive experiments, if the salt content is greater than 5 wt%, salt crystals will precipitate and clog the pipes after the reaction. This salt control ratio was obtained after extensive testing using raw materials collected from multiple devices at different times. Preferably, the salt content in the waste liquid to be oxidized is controlled between 1 and 5 wt% because the salt mainly comes from the raw materials, and fluctuations in the upstream process will cause fluctuations in the salt content. If the salt content is too low, the dilution ratio will be too high, which means that the reactor's processing capacity will increase and the equipment system will become larger; therefore, lower is not always better.

[0022] According to the present invention, the waste liquid obtained in step (1) is optionally diluted with water to obtain a waste liquid to be oxidized with a salt content controlled below 5 wt%. It is preferred to dilute the waste liquid obtained in step (1) with water to obtain a waste liquid to be oxidized with a salt content controlled below 5 wt% because the ozone reactor in the present invention will carry some water away from the system with mist. Long-term operation will lead to water imbalance in the system and enrichment of ion concentration. In order to achieve the treatment conditions, it is preferred to add fresh water to maintain the stability of the system.

[0023] According to the present invention, preferably, the filtration in step (1) removes insoluble particulate matter with a particle size of not less than 50 μm; and / or, the filtration adopts a bag filter, the minimum particle size removed by the bag filter being 50 μm.

[0024] According to some preferred embodiments of the present invention, the waste liquid containing salt and organic matter contains 0-10 wt% water, 10-30 wt% salt and 60-90 wt% organic matter.

[0025] According to some preferred embodiments of the present invention, the inorganic alkali in the inorganic alkaline solution is selected from strong alkalis, preferably sodium hydroxide and / or potassium hydroxide.

[0026] According to some preferred embodiments of the present invention, the salt is one or more selected from sulfates, chlorides, carbonates, and bicarbonates, and / or, the salt is an alkali metal salt; and / or,

[0027] The organic compound is one or more of ethylene glycol and oligomers with a degree of polymerization less than 20 (e.g., degrees of polymerization of 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, or any two values ​​or any range of any two values). Oligomers with a degree of polymerization less than 20 refer to oligomers of ethylene glycol with a degree of polymerization less than 20.

[0028] According to some preferred embodiments of the present invention, step (2) is performed in pH adjustment tank 1.

[0029] According to some preferred embodiments of the present invention, the salinity of the waste liquid to be oxidized is controlled at 1-5 wt%, and the pH is 10-13.

[0030] According to some preferred embodiments of the present invention, the conditions for the oxidation reaction in step (3) include: a residence time of 2-5 hours, preferably 3-5 hours, and / or a pressure not exceeding 0.1 MPa, and / or an ozone concentration of 0.1-3 mg / L in the effluent after the oxidation reaction. As mentioned above, the oxidation reaction of the present invention is a gas-liquid oxidation reaction. The conditions of the gas-liquid oxidation reaction are not only related to the amount of ozone fed, but also to the mass transfer efficiency and system characteristics related to the material properties. Through a large number of experiments, the present invention, by controlling the preferred residence time, under the above-mentioned oxidation reaction conditions, uses a simple method to transform alcohol- and salt-containing wastewater with extremely low biodegradability into wastewater with good biodegradability, achieving unexpected technical effects.

[0031] According to some preferred embodiments of the present invention, the pH of the waste liquid containing water-soluble organic acid salts obtained in step (3) is 8 to 9.

[0032] According to some preferred embodiments of the present invention, the first stream of waste liquid containing water-soluble organic salts accounts for 1-10 wt% of the total amount of waste liquid containing water-soluble organic salts obtained in step (3). From a material balance perspective, the electrodialysis system mainly treats the salts brought in by the raw materials. Therefore, when the salt concentration is high, less saline wastewater is extracted to ensure the stability of the membrane section. When the raw material salt concentration is low, more saline wastewater is extracted. Preferably, the processing capacity of the membrane section is determined by the amount of alkali required for the reaction. It is mainly to generate a portion of inorganic alkali (e.g., NaOH) solution water to be returned as raw material (as a catalyst) for the waste liquid to be oxidized. Therefore, it is not necessary for all the wastewater after ozone treatment to enter the membrane system. Preferably, only a portion (1-10 wt%) needs to be extracted to meet the requirements. This concentration is linked to the amount of process water added. If the alkali concentration is high and the water volume is low, more process water needs to be added to ultimately control the salt concentration and pH at the reactor inlet within a certain range. Conversely, less process water needs to be added.

[0033] According to some preferred embodiments of the present invention, the electrodialysis in step (4) is performed in an electrodialysis system. The principle of the electrodialysis system is the electrolysis of water and an ion exchange membrane. The hydrogen ions generated by the electrolysis of water combine with the anions of the salt to form an acid (organic acid + inorganic acid), and the hydroxide ions generated by the electrolysis of water combine with the cations of the salt to form an inorganic base, such as NaOH. The raw water after the ions are removed becomes desalinated water. The above-mentioned electrodialysis system is a conventional commercially available device in this field.

[0034] More preferably, the electrodialysis control conditions are: the concentration of inorganic alkali in the effluent is not higher than 10 wt%.

[0035] According to some preferred embodiments of the present invention, in step (5), the second stream of waste liquid containing water-soluble organic salts is combined with at least a portion of the obtained organic acid aqueous solution in pH adjustment tank two;

[0036] More preferably, the waste liquid obtained in pH adjustment tank two is combined with the demineralized water to obtain treated biodegradable waste liquid.

[0037] According to some preferred embodiments of the present invention, the pH of the biodegradable waste liquid obtained in step (5) is 6.5 to 7.5, the concentration of organic matter (organic alcohol) is ≤0.1wt%, and the B5 / C ​​ratio is >0.3.

[0038] As mentioned earlier, the organic acids produced by ozone products are excellent carbon sources for biochemical systems. This invention uses a simple method to transform alcohol- and salt-containing wastewater with extremely low biodegradability into wastewater with excellent biodegradability, achieving unexpected technical results.

[0039] A second aspect of the present invention is to provide a treatment system for wastewater containing salt and organic matter, preferably used in the treatment method described in the first aspect, such as... Figure 1 , 2 As shown, it includes:

[0040] A source of wastewater containing salt and organic matter, used to provide wastewater containing salt and organic matter;

[0041] A filter used to filter wastewater containing salt and organic matter;

[0042] Water source, used to dilute the filtered waste liquid containing salt and organic matter;

[0043] Inorganic alkali source, used to provide inorganic alkali;

[0044] Ozone source, used to provide ozone;

[0045] A reactor for reacting the waste liquid in the presence of inorganic alkaline solution and ozone;

[0046] The inorganic alkali source can be optionally connected to the inlet of one or more devices, such as a waste liquid source containing salt and organic matter, a filter, or a reactor.

[0047] An electrodialysis system is used to electrodialyze a stream of waste liquid from the reactor outlet to obtain inorganic alkaline aqueous solution, organic acid aqueous solution, and demineralized water.

[0048] The inorganic alkaline solution is returned to the inorganic alkaline solution source;

[0049] The organic acid aqueous solution and optional demineralized water are combined with another stream of waste liquid from the reactor outlet;

[0050] More preferably, it also includes pH adjustment tank one and / or pH adjustment tank two.

[0051] A pH adjustment tank is connected to a water source and is used to dilute the waste liquid containing salt and organic matter.

[0052] pH adjustment tank 2 is used to combine the organic acid aqueous solution with another stream of waste liquid from the reactor outlet.

[0053] For example, such as Figure 2 As shown, the present invention provides a method and system for treating organic waste liquid containing oligomers and salts, comprising:

[0054] (1) The waste liquid containing salt and organic matter (wheat alcohol and salt waste liquid) is first put into the filter to filter out insoluble particulate matter in order to protect the subsequent reactor and electrodialysis membrane system;

[0055] (2) The filtered alcohol and salt-containing waste liquid enters pH adjustment tank 1. pH adjustment tank 1 mainly plays two roles: first, to add a certain amount of process water to dilute the organic waste liquid; second, to adjust the pH of the reaction liquid in the system to be controlled within 10-13. The ultimate goal of adding process water and NaOH aqueous solution is to control the salt content in the reaction liquid between 1-5 wt% and pH = 10-13, so as to treat the waste liquid to be oxidized.

[0056] (3) The waste liquid to be oxidized and ozone are reacted in the reactor. After oxidation, the organic matter forms small molecule organic salts, and the COD decreases. At this time, the pH of the system drops to 8-9. The wastewater at the reactor outlet is divided into two streams. The first stream of waste liquid containing water-soluble organic salts (about 1wt% to 10wt% of alkaline saline wastewater at the reactor outlet) goes to the electrodialysis membrane system, and the rest goes to the pH adjustment tank 2 as the second stream of waste liquid containing water-soluble organic salts.

[0057] (4) The electrodialysis system separates the salts in the first stream of wastewater containing water-soluble organic salts (i.e., the extracted alkaline saline wastewater) into three streams through electrolysis: an inorganic alkaline aqueous solution, an organic acid aqueous solution, and a neutral desalinated water solution.

[0058] The inorganic alkaline aqueous solution (NaOH aqueous solution with a concentration of 1-10 wt%) is returned to pH adjustment tank 1 to realize the NaOH circulation within the system. The organic acid water is returned to pH adjustment tank 2 to neutralize with the second stream of waste liquid containing water-soluble organic salts (i.e., the remaining alkaline saline wastewater) to control the outlet pH to 6.5-7.5. The neutral desalinated water and the effluent from pH adjustment tank 2 are mixed and sent to the subsequent wastewater treatment device.

[0059] like Figure 2 As shown, the pH adjustment tank 2 in this invention can also be set before the filter, that is, process water and NaOH aqueous solution are added. The ultimate goal is to control the salt content in the reaction solution between 1-5 wt% and pH between 10 and 13, then filter to remove insoluble particulate matter, and then proceed with subsequent steps, which can also achieve the present invention.

[0060] As mentioned above, the oligomer-containing saline organic waste liquid in this invention contains 0-10 wt% water, 10-30 wt% salt, and the remainder is organic liquid. The types of salt include, but are not limited to, sulfates, chlorides, carbonates, and bicarbonates. The organic matter includes one or more of ethylene glycol and its oligomers with a degree of polymerization of less than 20.

[0061] The wastewater treated by the method of the present invention has a final pH of 6.5 to 7.5, an organic alcohol concentration of ≤0.1 wt%, and a B5 / C ​​ratio of >0.3.

[0062] Using the processing method of the present invention, the reactor does not require additional heating, the residence time is preferably controlled to be 2-5 hours, preferably 3-5 hours, the pressure is not greater than 0.1 MPa, and the ozone concentration in the effluent after oxidation reaction is 0.1-3 mg / L.

[0063] Compared with the prior art, the advantages of the present invention are:

[0064] This invention provides a method for treating wastewater containing salt and organic matter. Using ozone as an oxidant, the method employs a multi-step process to degrade oligosaccharides in the organic wastewater, primarily in an alcohol-containing aqueous solution. This process breaks down recalcitrant oligosaccharides into smaller organic molecules, improving biodegradability and transforming the recalcitrant organic wastewater into easily treatable industrial wastewater while eliminating COD. Furthermore, this invention can convert inorganic salts in the wastewater into other process materials for recycling within the system, reducing salt emissions. The organic acids produced by ozone are excellent carbon sources for biochemical systems. This invention uses a simple method to transform highly biodegradable alcohol- and salt-containing wastewater into well-biodegradable wastewater, achieving unexpected technical results.

[0065] Compared to combustion, this invention operates stably and does not have problems such as burner damage. Furthermore, this invention is almost entirely powered by electric equipment. If the source of electricity is green electricity in the future, the process will be a green and low-carbon process. Compared to wet oxidation, this invention has lower temperature and lower pressure, so it does not require a pressure vessel, has good safety, requires less equipment, and has low investment costs. Attached Figure Description

[0066] Figure 1 This is a process flow diagram of one specific embodiment of the method for treating oligomer-containing and salt-containing organic waste liquid of the present invention;

[0067] Figure 2 This is a process flow diagram of another specific embodiment of the method for treating oligomer-containing and salt-containing organic waste liquid of the present invention. Detailed Implementation

[0068] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0069] The detection method for B / C in this invention is: HJ 505-2009 Determination of Five-Day Biochemical Oxygen Demand (BOD5) in Water - Dilution and Inoculation Method;

[0070] The method for detecting alcohol content is: GB / T 14571.2-2018 Test methods for industrial ethylene glycol - Part 2: Determination of purity and impurities - Gas chromatography.

[0071] In the following examples, the organic alcohols in the alcohol- and salt-containing organic waste liquids are all ethylene glycol and their oligomers with a degree of polymerization of less than 20; the salts are alkali metal salts such as sulfates, chlorides, carbonates, and bicarbonates.

[0072] Unless otherwise specified, the raw materials, equipment, and testing methods used are all conventional types in this field.

[0073] Example 1

[0074] Adopting such Figure 2 The process flow shown involves a liquid containing alcohol and salt, with an alcohol content of 60 wt%, a water content of 10 wt%, and a salt content of 30 wt%. After filtration through a bag filter to remove insoluble particles smaller than 50 μm, the liquid is introduced into pH adjustment tank 1, where it is mixed with fresh process water and NaOH aqueous solution to adjust the pH to 10. The salt content is diluted to 1 wt% before the liquid enters the ozone reactor for reaction. Ozone is introduced and the residence time is 3 hours to ensure that the outlet ozone concentration is within the range of 0.1–3 mg / L and the pressure does not exceed 0.1 MPa.

[0075] After the reaction, 1 wt% of the liquid was extracted and sent to the electrodialysis system, while the remaining 99 wt% of the reaction solution entered pH adjustment tank 2. The 1 wt% NaOH aqueous solution obtained from the electrodialysis system was returned to pH adjustment tank 1. The acidic solution obtained from the electrodialysis system was mixed in pH adjustment tank 2, and then combined with the demineralized water obtained from the electrodialysis system to obtain the treated biodegradable wastewater with a pH reduced to 7.5 and a B / C ratio of 0.36. This wastewater then entered the subsequent wastewater treatment unit. The alcohol content, pH, and B / C of the treated wastewater are shown in Table 2.

[0076] Example 2

[0077] Wastewater containing salt and organic matter was treated using a method similar to that in Example 1. The differences are listed in Table 1. Unless otherwise specified, all other conditions are the same as in Example 1. The alcohol content, pH, and B / C ratio of the treated wastewater are shown in Table 2.

[0078] Example 3

[0079] Wastewater containing salt and organic matter was treated using a method similar to that in Example 1. The differences are listed in Table 1. Unless otherwise specified, all other conditions are the same as in Example 1. The alcohol content, pH, and B / C ratio of the treated wastewater are shown in Table 2.

[0080] Example 4

[0081] Wastewater containing salt and organic matter was treated using a method similar to that in Example 1. The differences are listed in Table 1. Unless otherwise specified, all other conditions are the same as in Example 1. The alcohol content, pH, and B / C ratio of the treated wastewater are shown in Table 2.

[0082] Example 5

[0083] The wastewater containing salt and organic matter was treated using a method similar to that in Example 1, except that the following method was used: Figure 1 The process flow shown involves first introducing the alcohol- and salt-containing organic waste liquid into pH adjustment tank 1 to adjust the pH and salt content, followed by filtration and subsequent treatment steps. Unless otherwise specified, all other conditions are the same as in Example 4.

[0084] Testing revealed that the alcohol content, pH, and B / C ratio of the treated biodegradable waste liquid were similar to those in Example 4.

[0085] Comparative Example 1

[0086] Wastewater containing salt and organic matter was treated using a method similar to that in Example 1. The differences are listed in Table 1. Unless otherwise specified, all other conditions are the same as in Example 1. The alcohol content, pH, and B / C ratio of the treated wastewater are shown in Table 2.

[0087] Comparative Example 2

[0088] Wastewater containing salt and organic matter was treated using a method similar to that in Example 1. The differences are listed in Table 1. Unless otherwise specified, all other conditions are the same as in Example 1. The alcohol content, pH, and B / C ratio of the treated wastewater are shown in Table 2.

[0089] Comparative Example 3

[0090] Wastewater containing salt and organic matter was treated using a method similar to that in Example 1. The differences are listed in Table 1. Unless otherwise specified, all other conditions are the same as in Example 1. The alcohol content, pH, and B / C ratio of the treated wastewater are shown in Table 2.

[0091] Table 1

[0092]

[0093] Table 2

[0094]

[0095]

[0096] B / C represents the ratio of BOD (Biochemical Oxygen Demand) to COD (Chemical Oxygen Demand), used to assess the biodegradability of water bodies. In organic wastewater treatment, the B / C ratio is primarily used to evaluate the biodegradability of wastewater. Although there is no universally applicable, officially established grading standard, based on experience from environmental science research and engineering practice, the range of B / C ratios can be correlated with the biodegradability of wastewater, thus creating a hypothetical grading. The following is a grading explanation based on this approach: B / C ratio ≥ 0.45: Within this range, most of the organic matter in the wastewater can be effectively degraded through biological treatment processes. 0.30 ≤ B / C ratio < 0.45: Within this range, the organic matter in the wastewater has a certain degree of biodegradability. B / C ratio < 0.30: Within this range, the biodegradability of the organic matter in the wastewater is poor, and the effectiveness of biological treatment is limited.

[0097] As seen in Examples 1-5, this invention uses ozone as an oxidant and, through a multi-step treatment process, degrades oligohydric alcohols in organic wastewater in a predominantly alcohol-containing aqueous solution. This process degrades recalcitrant oligomers into smaller organic molecules, thereby improving biodegradability and transforming the recalcitrant organic wastewater into easily treatable industrial wastewater, while also eliminating COD. Furthermore, this invention can convert inorganic salts in the wastewater into other process materials for recycling within the system, reducing salt emissions. The organic acids produced by ozone are excellent carbon sources for the biochemical system. This invention uses a simple method to transform alcohol- and salt-containing wastewater with extremely low biodegradability into highly biodegradable wastewater, achieving unexpected technical results.

[0098] As can be seen from the results in Table 2, Example 4 and Comparative Example 1 demonstrate the importance of controlling the pH of the reaction feed. If the pH does not reach the minimum requirement of 10, the alcohol content of the effluent will be high, the biodegradability will be low, and the requirements will not be met.

[0099] As can be seen from Example 4 and Comparative Example 2, if the salt content of the reaction influent is not controlled, it will affect the biodegradability and alcohol removal rate of the effluent, and will not meet the requirements.

[0100] As can be seen from Example 4 and Comparative Example 3, if the reaction residence time is not controlled, the biodegradability and alcohol removal rate of the effluent will be affected, and the requirements cannot be met.

[0101] In summary, pH control tank, dilution control of salinity, and reaction residence time are all important results obtained from the experiment.

[0102] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0103] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0104] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0105] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0106] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0107] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art believe that the combination is obviously unreasonable.

Claims

1. A method for treating wastewater containing salt and organic matter, wherein the organic matter is one or more of organic alcohols and oligomers with a degree of polymerization of less than 20; comprising: (1) The waste liquid containing salt and organic matter is filtered to obtain waste liquid with insoluble particulate matter removed; (2) The waste liquid obtained in step (1) is optionally diluted with water to obtain a waste liquid to be oxidized with the salt content controlled below 5 wt%. (3) The waste liquid to be oxidized is contacted with ozone to carry out an oxidation reaction, thereby obtaining a waste liquid containing water-soluble organic acid salts; In this process, an inorganic alkaline solution is added before step (1), or in one or more steps of step (1) or step (3) so that the pH of the waste liquid to be oxidized in step (3) is 10 to 13. (4) The waste liquid containing water-soluble organic salts is divided into two streams. The first stream of waste liquid containing water-soluble organic salts is subjected to electrodialysis to obtain three materials: inorganic alkali aqueous solution, organic acid aqueous solution, and desalinated water. The inorganic alkali aqueous solution is used as the raw material for obtaining the inorganic alkali solution used to oxidize the waste liquid. (5) The second stream of waste liquid containing water-soluble organic salts is combined with at least part of the obtained aqueous organic acid solution to make the pH 6.5 to 7.5, and optionally combined with the demineralized water to obtain the treated biodegradable waste liquid.

2. The processing method according to claim 1, characterized in that: The waste liquid containing salt and organic matter contains 0-10 wt% water, 10-30 wt% salt, and 60-90 wt% organic matter; and / or, The inorganic alkali in the inorganic alkaline solution is selected from strong alkalis, preferably sodium hydroxide and / or potassium hydroxide.

3. The processing method according to claim 1, characterized in that: The salt is one or more of sulfates, chlorides, carbonates, and bicarbonates, and / or the salt is an alkali metal salt; and / or, The organic compound is one or more of ethylene glycol and its oligomers with a degree of polymerization of less than 20.

4. The processing method according to claim 1, characterized in that: Step (2) is performed in pH adjustment tank one; and / or, The salt content of the waste liquid to be oxidized is controlled at 1-5 wt%, and the pH is 10-13.

5. The processing method according to claim 1, characterized in that: The conditions for the oxidation reaction in step (3) include: The residence time is 2 to 5 hours, preferably 3 to 5 hours, and / or the pressure is not greater than 0.1 MPa, and / or the ozone concentration in the effluent after the oxidation reaction is 0.1 to 3 mg / L.

6. The processing method according to claim 1, characterized in that: The pH of the waste liquid containing water-soluble organic acid salts obtained in step (3) is 8 to 9.

7. The processing method according to claim 1, characterized in that: The first stream of waste liquid containing water-soluble organic salts accounts for 1 to 10 wt% of the total amount of waste liquid containing water-soluble organic salts obtained in step (3); and / or, The electrodialysis described in step (4) is carried out in an electrodialysis system; preferably, the concentration of the inorganic alkaline aqueous solution obtained by electrodialysis is not higher than 10 wt%.

8. The processing method according to claim 1, characterized in that: In step (5), the second stream of waste liquid containing water-soluble organic salts is combined with at least part of the obtained organic acid aqueous solution in pH adjustment tank 2; Preferably, the waste liquid obtained in pH adjustment tank two is combined with the demineralized water to obtain treated biodegradable waste liquid.

9. The processing method according to any one of claims 1-8, characterized in that: The biodegradable waste liquid obtained in step (5) has a pH of 6.5 to 7.5, an organic matter concentration of ≤0.1wt%, and a B / C ratio of >0.

3.

10. A treatment system for wastewater containing salt and organic matter, preferably used in the treatment method according to any one of claims 1-9, comprising: A source of wastewater containing salt and organic matter, used to provide wastewater containing salt and organic matter; A filter used to filter wastewater containing salt and organic matter; Water source, used to dilute the filtered waste liquid containing salt and organic matter; Inorganic alkali source, used to provide inorganic alkali; Ozone source, used to provide ozone; A reactor for reacting the waste liquid in the presence of inorganic alkaline solution and ozone; The inorganic alkali source can be optionally connected to the inlet of one or more devices, such as a waste liquid source containing salt and organic matter, a filter, or a reactor. An electrodialysis system is used to electrodialyze a stream of waste liquid from the reactor outlet to obtain inorganic alkaline aqueous solution, organic acid aqueous solution, and demineralized water. The inorganic alkaline solution is returned to the inorganic alkaline solution source; The organic acid aqueous solution and optional demineralized water are combined with another stream of waste liquid from the reactor outlet; Preferably, it further includes a pH adjustment tank one and / or a pH adjustment tank two. A pH adjustment tank is connected to a water source and is used to dilute the waste liquid containing salt and organic matter. pH adjustment tank 2 is used to combine the organic acid aqueous solution with another stream of waste liquid from the reactor outlet.

Images