Method for purifying industrial organic wastewater and recovering organic matters

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a method for purifying industrial organic wastewater and recycling organic matters. Firstly, organic wastewater needs to be pretreated, and suspended solids such as solid impurities, dust and tar residues in the wastewater are separated; the method comprises the following steps of: separating a polar adsorption section, a medium polar adsorption section and a non-polar adsorption section into three adsorption sections under the conditions that the temperature is 5-45 DEG C, the pressure is 0.5-5.0 MPa and the flow rate is 1-50BV / h, after the three resin adsorption tanks are saturated in adsorption, performing desorption by using methanol as a solvent, rinsing the resin after desorption by using clear water, recycling the resin, performing steam stripping on the methanol rinsing liquid by using a steam stripping tower to recover methanol, and performing vacuum drying on the resin after the desorption is completed. Tower bottoms of the stripping tower are organic matters separated from the organic wastewater. According to the invention, the wastewater is purified, the purified clear water can reach the discharge standard or the reuse standard, the pollution of the wastewater to the environment is effectively reduced, the separated organic matters are classified and recovered according to different polarities and can be sold as commodities or fuels, the process operation conditions are mild, and the operation cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, in particular to a method for purifying industrial organic wastewater and recovering organic matter. Background Art

[0002] Industrial high-concentration organic wastewater has the following key characteristics: First, it has a high concentration of organic matter, with COD levels typically exceeding 2,000 mg / L, sometimes reaching tens of thousands or even hundreds of thousands of mg / L. Comparatively, the BOD is relatively low, with many wastewaters having a BOD to COD ratio of less than 0.3. Second, it has a complex composition and contains toxic substances. The organic matter in wastewater is primarily aromatic and heterocyclic compounds, and also often contains sulfides, nitrides, heavy metals, and toxic organic matter. Third, it has a high color and an odor, with some wastewater emitting a pungent odor that negatively impacts the surrounding environment. Fourth, it is highly acidic and alkaline.

[0003] There are currently three processes for treating organic wastewater: 1. Oxidation-adsorption method After dilution, high-concentration wastewater undergoes initial coagulation and adsorption treatment with pulverized coal. This is followed by catalytic oxidation and acidic coagulation using Fenton's reagent, followed by further coagulation and adsorption with pulverized coal. This method achieves excellent treatment results, achieving 100% color reduction and 90% COD reduction, respectively. However, this method suffers from complex process conditions and high treatment costs. Currently, the high cost of treating low-concentration wastewater has prevented widespread adoption.

[0004] The incineration method is suitable for treating high-concentration organic wastewater. After pretreatment, the wastewater is pressurized, filtered, and metered before being delivered to the top of the furnace arch. High-pressure air atomization nozzles are then sprayed into the furnace for evaporation and incineration. This method can thoroughly treat high-concentration organic wastewater while ensuring safe boiler operation. Its advantages include low initial investment and operating costs. When specialized techniques are employed, the incineration effect is excellent, reducing the carbon content of both ash and fly ash without significantly impacting boiler output or efficiency.

[0005] The shortcomings of this method in actual promotion and application are: ① The amount of wastewater is limited by the matching boiler; ② The composition of the wastewater should be analyzed in detail to ensure that it does not affect the combustion of the boiler itself; ③ The method needs further in-depth research in theory.

[0006] 2. Adsorption method Adsorption involves using a solid adsorbent with strong adsorption capacity to concentrate one or more components in wastewater on a solid surface. Commonly used adsorbents include activated carbon and resins. Activated carbon is difficult to regenerate and elute. Resin adsorption offers advantages such as a wide range of applications, immunity to inorganic salts in wastewater, excellent adsorption, ease of elution and regeneration, and stable performance. Therefore, resins are the most commonly used adsorbents in the treatment of ultra-high-concentration organic wastewater. Resin adsorption is an effective method for treating wastewater containing phenols, aniline, organic acids, nitro compounds, pesticides, and dye intermediates. However, it is not widely used in the treatment of low-concentration organic wastewater.

[0007] 3. Traditional biochemical process Biological treatment is commonly used to treat organic wastewater, primarily using aerobic methods or modified aerobic methods (such as the A / O process). Some also employ anaerobic biological treatment. The actual application of these processes both domestically and internationally reveals significant challenges, including lengthy process flows, the large amount of additives (such as carbon sources and pH adjustment agents), and high costs. This results in high overall unit water cost and unit water cost. For example, the ideal unit water cost for coking wastewater treatment is at least RMB 10 to 8 per cubic meter. Some international companies do not even consider treatment cost as a primary factor.

[0008] Traditional methods for treating coking ammonia wastewater suffer from poor treatment results and the inability to effectively recycle organic matter, leading to wasteful resources and increased treatment costs. Therefore, developing a process for purifying industrial organic wastewater and recovering organic matter is of great practical significance. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for purifying industrial organic wastewater and recovering organic matter, which can efficiently remove various organic matter in coking ammonia distillation wastewater, achieve wastewater purification, and simultaneously recover organic matter in the wastewater, thereby improving resource utilization, reducing treatment costs, and turning organic wastewater into valuable resources.

[0010] Organic wastewater impurities are mainly organic matter. The core of this technical solution is to utilize the principle of selective adsorption of organic matter by macroporous adsorption resin. By constructing a suitable process flow, the organic matter in the organic wastewater is separated step by step, ultimately achieving the purpose of purifying the organic wastewater.

[0011] In order to meet the prerequisites for adsorption by macroporous adsorption resin, the raw organic wastewater needs to be pretreated to separate solid components such as oil droplets and solid dust in the organic wastewater.

[0012] Macroporous adsorption resin adsorption is divided into three adsorption sections: polar, medium polar, and non-polar, which gradually separate the organic components in the organic wastewater.

[0013] The adsorption resin after adsorption saturation is rinsed with methanol and then regenerated for use. The methanol rinse liquid is separated by distillation to obtain methanol and three organic solutions with different polarities. The methanol can be reused and the organic solution can be sold as a solvent or a crude processed product.

[0014] The specific steps include: 1. Pretreatment: Filter the coking ammonia wastewater at a temperature of 0-60℃ and unlimited pressure using a security filter or ceramic filter to separate solid impurities, dust, tar residue and other suspended matter in the wastewater to obtain pretreated wastewater; 2. First-stage non-polar resin adsorption: The pretreated wastewater is passed through the first-stage non-polar resin adsorption tank. The filtration temperature is controlled at 5-45°C, the pressure is controlled at 0.5MPa-5.0MPa, and the flow rate is controlled at 1-50BV / h. The non-polar resin, which has a styrene-divinylbenzene (Styrene-DVB) copolymer as its skeleton and does not contain polar groups, uses van der Waals forces to adsorb non-polar or weakly polar substances in the wastewater, such as flavonoids, terpenes, fat-soluble components and other non-polar organic matter. The wastewater after separation of non-polar organic matter enters the second-stage adsorption tank. 3. Second-stage medium-polarity resin adsorption: Wastewater purified by the first-stage non-polar resin adsorption tank enters the second-stage medium-polarity resin adsorption tank, maintaining the filtration temperature at 5-45°C, the pressure at 0.5MPa-5.0MPa, and the flow rate at 1-50BV / h. The chemical structure of the medium-polarity resin is to introduce weak polar groups such as ester and ketone groups into the styrene skeleton. It has both hydrophobic and hydrophilic effects, suitable for adsorbing medium-polar substances and separating medium-polarity organic matter such as alkaloids, saponins, and phenolic acid compounds. The wastewater after separation of medium-polarity organic matter enters the third-stage adsorption tank. Representative models of medium-polarity resins are AB-8, XAD-7, and HPD300; 4. Third-stage polar resin adsorption: Wastewater purified by the second-stage medium-polarity resin adsorption tank enters the third-stage polar resin adsorption tank, maintaining the filtration temperature between 5 and 45°C, the pressure between 0.5 MPa and 5.0 MPa, and the flow rate between 1 and 50 BV / h. Polar resins contain highly polar groups in their chemical structure, such as hydroxyl, amino, and amide groups. They adsorb polar substances, such as sugars, polyphenols, and amino acids, through hydrogen bonding or dipole interactions. After separating the polar organic substances, purified water is obtained. 5. Resin analysis and organic matter recovery: When the three resin adsorption tanks are saturated with adsorption, methanol is used as the solvent for analysis. After the analysis, the resin is rinsed with clean water and reused. The methanol rinse liquid is stripped in a stripping tower to recover methanol. The bottom liquid of the stripping tower is the organic matter separated from the organic wastewater, thereby realizing the recovery of organic matter.

[0015] Representative models of the above-mentioned non-polar resins are: HPD100, XAD-2, and D101.

[0016] Representative models of the above-mentioned medium polarity resins are: AB-8, XAD-7, and HPD300.

[0017] Representative models of the polar resins mentioned above are D-4020, S-8, and XAD-1180.

[0018] Non-polar resins adsorb non-polar or weakly polar substances (such as hydrophobic molecules) through van der Waals forces, and can adsorb flavonoids, terpenes, and fat-soluble components.

[0019] The medium polarity resin is characterized by its hydrophobic and hydrophilic properties, and is suitable for the separation of medium polar substances, alkaloids, saponins, and phenolic acid compounds.

[0020] Polar resins adsorb polar substances (such as water-soluble components) through hydrogen bonds or dipole effects, and are mainly used for the purification of sugars, polyphenols, and amino acids.

[0021] Compared with the existing technology, the present invention has the following advantages: 1. The present invention uses resin adsorption tanks of different polarities to sequentially separate non-polar, medium-polar, and polar organic matter in wastewater. This can effectively remove various organic matter from coking ammonia evaporation wastewater, purifying the wastewater. The purified water can meet discharge or reuse standards, effectively reducing wastewater pollution to the environment.

[0022] 2. Methanol is used to decompose the adsorption saturated resin and the methanol is recovered through a stripping tower. At the same time, the separated organic matter is obtained and classified and recovered according to different polarities. The recovered organic solution can be sold as a commodity or fuel, with low operating costs.

[0023] 3. The process has mild operating conditions, and parameters such as temperature, pressure and flow rate are easy to control. The equipment investment and operating costs are low, with good economic and environmental benefits, and is suitable for industrial application. DETAILED DESCRIPTION

[0024] The technical solutions and effects of the present invention are further described below through specific embodiments. Example 1

[0025] 1. Pretreatment: Take the coking ammonia evaporation wastewater and filter it with a security filter at a temperature of 25°C and normal pressure to remove solid impurities, dust, tar residue and other suspended matter in the wastewater to obtain pretreated wastewater; 2. First-stage non-polar resin adsorption: The pretreated wastewater is passed into the first-stage adsorption tank filled with HPD100 non-polar resin. The filtration temperature is controlled at 20°C, the pressure is 1.0 MPa, and the flow rate is 10 BV / h. The non-polar organic matter in the wastewater is adsorbed. The wastewater after the non-polar organic matter is separated enters the second-stage adsorption tank. 3. Second-stage medium-polarity resin adsorption: The wastewater enters the second-stage adsorption tank filled with AB-8 medium-polarity resin, maintaining the filtration temperature at 20°C, the pressure at 1.0 MPa, and the flow rate at 10 BV / h to adsorb medium-polarity organic matter. After separating the medium-polarity organic matter, the wastewater enters the third-stage adsorption tank; 4. Third-stage polar resin adsorption: Wastewater enters a third-stage adsorption tank filled with D-4020 polar resin, maintaining a filtration temperature of 20°C, a pressure of 1.0 MPa, and a flow rate of 10 BV / h. Polar organic matter is adsorbed to produce purified water. Testing has shown a significant reduction in the COD content of the purified water, meeting discharge standards. 5. Resin Desorption and Organic Recovery: When the three resin adsorption tanks reach saturation, methanol is used as the solvent for desorption. The resin is rinsed with clean water and reused. The methanol rinse is then stripped in a stripping tower to recover the methanol. The stripping tower bottom liquid represents the separated organic matter, thus enabling organic recovery. Example 2

[0026] 1. Pretreatment: Take the coking ammonia evaporation wastewater and filter it with a ceramic filter at a temperature of 30°C and normal pressure to obtain pretreated wastewater; 2. First-stage non-polar resin adsorption: The pretreated wastewater is passed into the first-stage adsorption tank filled with XAD-2 non-polar resin. The filtration temperature is controlled at 25°C, the pressure is 1.5 MPa, and the flow rate is 15 BV / h. After the non-polar organic matter is adsorbed, the wastewater enters the second-stage adsorption tank. 3. Second stage medium polarity resin adsorption: The wastewater enters the second stage adsorption tank filled with XAD-7 medium polarity resin, maintaining the filtration temperature at 25°C, the pressure at 1.5MPa, and the flow rate at 15BV / h. After the medium polarity organic matter is adsorbed, the wastewater enters the third stage adsorption tank; 4. Third-stage polar resin adsorption: Wastewater enters the third-stage adsorption tank filled with S-8 polar resin, maintaining a filtration temperature of 25°C, a pressure of 1.5 MPa, and a flow rate of 15 BV / h to produce purified water. Testing shows that all indicators of the purified water meet reuse requirements. 5. Resin decomposition and organic matter recovery: The adsorption saturated resin is decomposed with methanol, and the decomposed resin is rinsed and reused. The methanol rinse liquid is treated in a stripping tower to recover methanol, and the organic matter is recovered from the bottom liquid of the tower. Example 3

[0027] Pretreatment: Coking ammonia evaporation wastewater was taken at a temperature of 30°C; adsorption tank: the filtration temperature was controlled at 30°C, the pressure was 2.0 MPa, and the flow rate was 20 BV / h; the non-polar resin model was D101, the medium-polar resin model was HPD300, and the polar resin model was XAD-1180. Other procedures were the same as in Example 1. Example 4

[0028] Pretreatment: Coking ammonia evaporation wastewater was taken at a temperature of 40°C; adsorption tank: filtration temperature was controlled at 40°C, pressure was 2.5 MPa, and flow rate was 35 BV / h; non-polar resin model was HPD100, medium polar resin model was XAD-7, and polar resin model was D-4020. Other procedures were the same as in Example 2.

[0029] The above examples show that the coking ammonia evaporation wastewater purification and organic matter recovery process of the present invention can effectively purify wastewater and recover organic matter, and has good application effects.

Claims

1. A method for purifying industrial organic wastewater and recovering organic matter, characterized in that The specific steps include: (1) Pretreatment: Temperature 0-60℃, pressure unlimited, use security filter or ceramic filter to separate solid impurities, dust, tar residue and other suspended matter in wastewater; (2) The pretreated wastewater is passed into the first-stage non-polar resin adsorption tank, and the filtration temperature is strictly controlled at 5-45°C, the pressure is 0.5MPa-5.0MPa, and the flow rate is 1-50BV / h. The non-polar organic matter in the wastewater is separated and then enters the second-stage adsorption tank; (3) The wastewater purified by the first-stage non-polar resin adsorption tank enters the second-stage medium-polar resin adsorption tank, and the gas enters the second-stage medium-polar resin adsorption tank, still maintaining the above-mentioned temperature, pressure and flow rate conditions, and enters the third-stage adsorption tank after separating the medium-polar organic matter; (4) The gas purified by the second-stage medium-polarity resin adsorption tank enters the third-stage polarity resin adsorption tank. The specific filtration conditions are still the temperature of 5-45 ° C, the pressure of 0.5 MPa -5.0 MPa, and the flow rate of 1-50 BV / h. After separating the polar organic matter, purified water is obtained; (5) After the three resin adsorption tanks are saturated with adsorption, methanol is used as the solvent for decomposition. After decomposition, the resin is rinsed with clean water and reused. The methanol rinse liquid is stripped in a stripping tower to recover methanol. The bottom liquid of the stripping tower is the organic matter separated from the organic wastewater.

2. The method for purifying hydrogen sulfide gas produced as a by-product of a chemical industry according to claim 1, characterized in that The non-polar resin is based on a styrene-divinylbenzene (Styrene-DVB) copolymer and does not contain polar groups. Representative non-polar resin models are: HPD100, XAD-2, and D101.

3. The method for purifying hydrogen sulfide gas produced as a by-product of a chemical industry according to claim 1, characterized in that The medium polarity resin has a chemical structure in which weak polar groups such as ester groups and ketone groups are introduced into a styrene skeleton. Representative resin models include AB-8, XAD-7, and HPD300.

4. The method for purifying hydrogen sulfide gas produced as a by-product of a chemical industry according to claim 1, characterized in that The polar resin has a chemical structure containing strong polar groups such as hydroxyl, amino, and amide groups. Representative resin models include D-4020, S-8, and XAD-1180.

5. A method for purifying hydrogen sulfide gas produced as a by-product of a chemical industry according to claim 1 or 2, characterized in that The non-polar resin adsorbs non-polar or weakly polar substances such as hydrophobic molecules through van der Waals force, and can adsorb flavonoids, terpenes, and fat-soluble components.

6. A method for purifying hydrogen sulfide gas produced as a by-product of a chemical industry according to claim 1 or 3, characterized in that The medium polarity resin has both hydrophobic and hydrophilic effects and is suitable for separating medium polar substances, alkaloids, saponins and phenolic acid compounds.

7. A method for purifying hydrogen sulfide gas produced as a by-product of a chemical industry according to claim 1 or 4, characterized in that The polar resin adsorbs polar substances such as water-soluble components through hydrogen bonding or dipole action, and is mainly used for the purification of sugars, polyphenols, and amino acids.