Activated curing agent and method for purifying phenol-ammonia-containing wastewater by using same

Abstract

The method comprises the following steps: adding the activated curing agent into wastewater, controlling the temperature of the wastewater to be 45-60 DEG C, controlling the pH value of the wastewater to be 9-11, and then filtering to remove a solid phase so as to obtain a pretreatment solution; rectifying and separating the pretreatment liquid to obtain an ammonia water product and crude phenol water; adjusting the pH value of the crude phenol water to 4.5-6.5 by using inorganic acid, then removing insoluble substances separated out from the crude phenol water, and rectifying to remove hydrogen sulfide in the crude phenol water to obtain purified phenol water; extracting and purifying the phenol water by using an organic extracting agent to obtain purified water and a loaded organic phase; and recovering phenol from the loaded organic phase to obtain a phenol product, and returning the obtained regenerated extractant to purified phenol water for recycling. According to the scheme, the problems of coking and blocking in the conventional phenol-ammonia wastewater treatment process can be effectively solved, the energy consumption and medicament consumption in the deamination process are reduced, the formation of a third phase in the phenol extraction process is reduced, the purity of an ammonia water product and a phenol product is improved, and the pollutant removal rate of purified wastewater is improved.

Description

Technical Field

[0001] This invention relates to the field of high-concentration wastewater treatment, specifically to an active curing agent and a method for purifying phenol-ammonia-containing wastewater using the curing agent. Background Technology

[0002] Large amounts of high-concentration phenol-ammonia-containing wastewater are generated during coal chemical production processes such as coking, semi-coke, coal gasification, coal pyrolysis, and coal tar processing. This type of wastewater typically contains large amounts of ammonia nitrogen, phenolic substances, as well as pollutants such as sulfides, tar and fluorides, and suspended coke dust.

[0003] Currently, high-concentration phenol and ammonia wastewater is generally treated by distillation to remove acid and ammonia, and extraction to remove phenol. However, related industrial equipment generally suffers from problems such as high investment, large footprint, high energy consumption, poor treatment effect, and unstable operation. The main problems are as follows:

[0004] First, there is a lack of effective wastewater pretreatment technology, especially the inability to remove dissolved tar and extremely small suspended solids from the wastewater beforehand. This leads to frequent scaling and clogging during the operation of subsequent equipment such as ammonia stripping and deacidification towers, extraction towers, and heat exchangers. In particular, the ineffective removal of tar from the wastewater causes tar impurities to enter the extractant during the extraction process, forming a third phase, resulting in operational instability and extractant loss. Furthermore, these impurities enter the phenol product, causing excessive levels of neutral oil and other impurities, thus reducing product quality. Second, the operating temperatures of existing ammonia stripping and deacidification and phenol extraction are mismatched. The operating temperature is high, and repeated heating and cooling of the materials are required, resulting in high overall energy consumption of the equipment. Third, existing phenol and ammonia wastewater treatment technologies often only target ammonia nitrogen, sulfides, and phenols, failing to remove other ions, especially fluoride ions. This leads to excessively high fluoride ion concentrations in the downstream wastewater, impacting the operation of zero-discharge wastewater treatment. Fourth, existing technologies use sodium hydroxide to decompose and fix ammonium salts. The repeated adjustment of pH values ​​introduces soluble acids and alkalis, increasing the final TDS index of the wastewater and causing secondary pollution. Summary of the Invention

[0005] This invention addresses the problem of complex and difficult-to-remove pollutants in phenol-ammonia-containing wastewater by providing an active curing agent and a method for purifying such wastewater using this agent. This invention effectively removes tar, suspended solids, and other impurities from the wastewater, deeply removes pollutants such as sulfides and fluorides, reduces the total dissolved solids (TDS) of the wastewater, and has low energy consumption. It solves the problems of existing technologies, such as tar and suspended impurities clogging equipment and pipelines, tar, sulfides, and ammonia contaminating the extractant, and high chemical consumption, high operating energy consumption, and high operating costs.

[0006] This application provides a method for purifying phenol-ammonia-containing wastewater using an active curing agent, characterized by the following steps:

[0007] S101: Add an active curing agent to the phenol-ammonia-containing wastewater and control the water phase temperature at 45~60℃, control the pH value of the phenol-ammonia-containing wastewater at 9~11, and then filter to remove the solid phase to obtain a pretreated liquid.

[0008] S201: The pretreatment liquid is subjected to deammoniation treatment to obtain ammonia water product and grade 1 crude phenol water;

[0009] S301: Add concentrated sulfuric acid to the first-grade crude phenol water to adjust the pH value to 4.5~6.5, and then remove the precipitated insoluble matter to obtain the second-grade crude phenol water;

[0010] S401: The second-stage crude phenol water is subjected to hydrogen sulfide removal treatment to obtain purified phenol water;

[0011] S501: Extract the purified phenolic water using an organic extractant to obtain dephenolized water and a supported organic phase;

[0012] S601: Phenol is recovered from the supported organic phase to obtain a phenol product, and a regenerated extractant is obtained and returned to the purified phenol water for recycling.

[0013] Preferably, the method for preparing the active curing agent is as follows:

[0014] (1) Use 40%~70% by mass of alkaline oxide ultrafine powder with a particle size of less than 50μm, 5%~10% by mass of zinc oxide and 30%~60% by mass of powdered activated carbon, mix thoroughly, then add 10%~30% by mass of water to wet, and press into granules with a diameter of 3~6mm and a length of 5~10mm at a molding pressure of 100-200 kN / cm2;

[0015] (2) The granular material is activated by high-temperature heat treatment to obtain an activated curing agent:

[0016] ① In the temperature range of room temperature to 200℃, the temperature is increased at a rate of 5 to 10℃ / minute. After the temperature reaches 200℃, it is held for 50 to 100 minutes. The operating pressure is -5 to 10 kPaG. The atmosphere is air. When the material temperature is >110℃, air is supplied. The ratio of the volume of purging air (Nm3 / h) to the volume of granular material (m3 / h) is 3 to 15.

[0017] ② Increase the temperature at a rate of 8~12℃ / minute within the temperature range of 200~600℃. After the temperature reaches 600℃, maintain the temperature for 30~60 minutes. The operating pressure is -5~10KPaG. The atmosphere is ammonia. The gas is supplied evenly throughout the process, with the gas supply ratio being 3~10 times the volume of purging gas (Nm3 / h) to the volume of granular material (m3 / h).

[0018] ③ Increase the temperature at a rate of 8-12℃ / minute within the temperature range of 600-800℃. After reaching 800℃, hold the temperature for 20-30 minutes. The operating pressure is -5-10KPaG, and the atmosphere is oxygen-free.

[0019] ④ Physically cool the heat-treated material to room temperature ~ 90℃;

[0020] (3) The activated curing agent is pulverized and sieved to the following particle size distribution:

[0021] The mass percentage of particles with a diameter of 100~200μm is 10%, the mass percentage of particles with a diameter of 50~100μm is 60%, the mass percentage of particles with a diameter of 30~50μm is 15%, and the mass percentage of particles with a diameter of <30μm is 15%.

[0022] Preferably, the saturated active curing agent is regenerated to restore its active sites and then recycled. The method for regenerating the active curing agent is as follows:

[0023] (1) The active curing agent is filtered out from the water to obtain wet material;

[0024] (2) The wet material is pressed, dehydrated and extruded to obtain granules with a diameter of 3-6 mm and a length of 5-10 mm;

[0025] (3) The granules are subjected to high-temperature calcination at a temperature of 700-900°C. At the same time as calcination, a gas with an oxygen concentration of 5%-60% is introduced. After reaching the calcination temperature, the calcination treatment time is 1-2 hours to obtain a regenerated active curing agent.

[0026] (4) The regenerated curing agent is crushed and sieved to the following particle size distribution:

[0027] The mass percentage of particles with a diameter of 100-200μm is 10%, the mass percentage of particles with a diameter of 50-100μm is 60%, the mass percentage of particles with a diameter of 30-50μm is 15%, and the mass percentage of particles with a diameter of less than 30μm is 15%.

[0028] Preferably, the active curing agent adsorbs impurities in the phenol-ammonia-containing wastewater through its surface alkaline active sites and active ions. The adsorption process is in a liquid-solid fluidized state or a suspended state. The proportion of the curing agent in the wastewater is 0.5% to 5%, and the residence time of the adsorption process is 0.5 hours to 2 hours.

[0029] Preferably, the regenerated active curing agent is used in a ratio of 1:2 to 1:5.

[0030] Preferably, the ammonia removal process is a vacuum ammonia stripping operation, with an operating temperature of 50~80℃ and an operating pressure of 5KPaA~20KPaA.

[0031] Preferably, the acid-insoluble substance is added to the pressing, dehydration, and extrusion molding processes and thoroughly mixed with the active curing agent.

[0032] Preferably, the desulfurization treatment method is vacuum stripping or vacuum distillation, with an operating temperature of 50~80℃ and an operating pressure of 5KPaA~20KPaA.

[0033] Preferably, the extractant comprises any one or a combination thereof of N,N-bis(1-methylheptyl)acetamide, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester and aviation kerosene, methyl isobutyl ketone, diisopropyl ether, methyl tert-butyl ketone, and butyl acetate.

[0034] Preferably, the phenol-removed water is adjusted to a pH of 7-8 using lime milk and then filtered to remove the generated precipitate to obtain purified water.

[0035] Compared with the prior art, the active curing agent and the method for purifying phenol-ammonia-containing wastewater provided in this application have at least the following beneficial effects:

[0036] 1. This invention can effectively remove tar, suspended solids and other impurities from wastewater, solving the problem of tar and suspended impurities clogging equipment and pipes and requiring frequent maintenance in the treatment of phenol and ammonia wastewater in existing technologies.

[0037] 2. This invention deeply removes contaminants such as tar, sulfides, and fluorides, avoiding a series of problems such as foaming of the extractant and the generation of a large amount of third phase caused by impurities during subsequent extraction processes, thus reducing extractant consumption.

[0038] 3. The present invention removes ammonia and hydrogen sulfide at low temperatures, and the operating temperature is basically the same as that of the subsequent phenol removal, which reduces a lot of heating and cooling energy consumption and has lower operating costs compared with the existing technology.

[0039] 4. This invention can simultaneously remove fluoride ions and cyanide from wastewater, thereby reducing the TDS content in wastewater. Attached Figure Description

[0040] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0041] Figure 1 This is a schematic diagram of a method for purifying phenol-ammonia-containing wastewater provided by the present invention;

[0042] Figure 2 This is a schematic diagram of a system for purifying phenol- and ammonia-containing wastewater provided by the present invention; Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0044] An embodiment of the first aspect of the present invention provides an active curing agent and a method for purifying phenol-ammonia-containing wastewater using the curing agent, such as... Figure 1 As shown, the method for purifying phenol-ammonia-containing wastewater may include the following steps:

[0045] S101 Pretreatment steps to remove acidified tar, alkali-insoluble matter, and suspended solids;

[0046] S201 ammonia removal step;

[0047] S301 acidification and impurity removal step;

[0048] S401 hydrogen sulfide removal step;

[0049] S501 extraction and phenol removal step;

[0050] S601 extractant regeneration steps;

[0051] S701 conditioning and desalination steps.

[0052] The specific implementation of step S101 can be to control the temperature of the phenol-ammonia-containing wastewater at 45~60℃, then add an active curing agent to the phenol-ammonia-containing wastewater, and control the pH value of the wastewater at 9~11 through the alkalinity released by the active curing agent, and then filter to remove the solid phase to obtain the pretreated liquid.

[0053] The active curing agent added in step S101 can be prepared as follows:

[0054] (1) Use 40%~70% calcium oxide by mass, 5%~10% zinc oxide by mass (all raw materials are ultrafine powder with a particle size <50μm), and 30%~60% powdered activated carbon (particle size <50μm) by mass to mix thoroughly, then add 10%~30% water to wet, and press into granules with a diameter of 3~6mm and a length of 5~10mm at a molding pressure of 100-200 kN / cm2;

[0055] (2) The above granular material is activated by high-temperature heat treatment under the following conditions to obtain an activated curing agent;

[0056]

[0057] (3) The above-mentioned activating and curing agent is crushed and sieved to the following particle size distribution:

[0058]

[0059] In step S101, the alkaline active sites and active ions on the surface of the active curing agent interact with soluble organic matter such as acid tar and insoluble oils, as well as pollutants such as sulfides, sulfates, and fluoride ions in the phenol-ammonia wastewater through chemical and physical adsorption. The pollutant ions or molecules are cured by the active curing agent and then separated from the aqueous phase by filtration.

[0060] Step S101 further includes regenerating the filtered and separated adsorbed saturated curing agent to restore its active sites and recycling it. The regeneration method is as follows:

[0061] (1) The wet material obtained by filtering and separating from the aqueous phase is pressed, dehydrated and extruded to obtain granules with a diameter of 3~6mm and a length of 5~10mm;

[0062] (2) The above granules are regenerated by high-temperature heat treatment. The regeneration atmosphere is an oxygen-containing atmosphere (oxygen concentration 5%~60%). The heat treatment temperature is 700~900℃ for 1~2 hours. The heat treatment reaction method is fluidized bed calcination or rotary kiln calcination to obtain an activated curing agent.

[0063] (3) The above-mentioned activating curing agent is pulverized and sieved to the following particle size distribution for use as a regenerating curing agent:

[0064]

[0065] In step S101, the amount of fresh curing agent and the total amount of curing agent used are determined / controlled based on the composition and content of characteristic pollutants in the wastewater, specifically calculated according to the method shown in the table below:

[0066]

[0067] In step S101, the contact mode between the curing agent and the phenol-ammonia-containing wastewater can be liquid-solid fluidization or suspension. Generally, the proportion (mass ratio) of the total curing agent in the wastewater is ≤5%, and the contact time between the curing agent and water is controlled between 30 minutes and 120 minutes.

[0068] The specific implementation of step S201 can be vacuum ammonia stripping or steam stripping to remove ammonia nitrogen from the wastewater and obtain ammonia water product and grade 1 crude phenol water.

[0069] In step S201, vacuum ammonia stripping is preferably used, with an operating temperature of 50~80℃ and an operating pressure of 5KPaA~20KPaA.

[0070] It is worth noting that during the extension from step S101 to step S201, a portion of the active curing agent added in step S101 dissociates into ions. These ions can chemically combine with acidic substances such as hydrogen sulfide and phenol in the wastewater, thereby stabilizing the sulfides and phenols in the wastewater and greatly reducing the volatility of hydrogen sulfide and phenol. This prevents the escape of hydrogen sulfide and phenol during the ammonia removal process, resulting in a purer ammonia product.

[0071] The specific implementation of step S301 can be to add concentrated sulfuric acid to the first-grade crude phenol water to adjust the pH value of the first-grade crude phenol water to 4.5~6.5, and then filter to separate the precipitated insoluble matter to obtain the second-grade crude phenol water.

[0072] In step S301, concentrated sulfuric acid can be added using a static mixer, a Venturi mixer, or a stirred reactor.

[0073] In step S301, the main components of the insoluble matter separated by filtration are organic substances such as acid tar and acid asphalt. This part of the insoluble matter can be sent to step S101 to be mixed with the curing agent for regeneration. These acid tar and acid asphalt can provide the bonding function of the curing agent during extrusion molding.

[0074] A specific implementation of step S401 can be to treat the second-stage crude phenol water by distillation or stripping to remove hydrogen sulfide and obtain purified phenol water.

[0075] In step S401, vacuum distillation or vacuum stripping is preferably used, with an operating temperature of 50~80℃ and an operating pressure of 5KPaA~20KPaA.

[0076] The specific implementation of step S501 can be liquid-liquid extraction. The specific extraction process can be physical extraction or complexation extraction. Phenolic substances in wastewater are removed by extraction to obtain dephenolized water, and the phenols are transferred to the extractant to become the supported organic phase.

[0077] In step S501, the extractant used may include any one or a combination of N,N-bis(1-methylheptyl)acetamide, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester and a mixture of aviation kerosene / solvent oil, methyl isobutyl ketone, diisopropyl ether, methyl tert-butyl ketone, butyl acetate, or other similar extractants.

[0078] In one embodiment of the present invention, the extractant used in step S501 includes N,N-bis(1-methylheptyl)acetamide and solvent oil No. 260 in a mass ratio of 1:5 to 1:2.

[0079] In another embodiment of the present invention, the extractant used in step S501 is diisopropyl ether or methyl tert-butyl ketone.

[0080] According to an embodiment of the present invention, step S501 includes performing one-stage or multi-stage countercurrent extraction of the extractant and purified phenolic water at a ratio of 10:1 to 1:10.

[0081] In one embodiment of the present invention, step S501 includes extraction using a centrifugal extractor, wherein the number of extraction stages ranges from three to multiple stages.

[0082] In one embodiment of the present invention, step S501 includes extraction using a rotating disc extraction tower.

[0083] A specific implementation of step S601 may be to regenerate the supported organic phase to obtain a phenol product and a regenerated extractant, which is then recycled in step S501.

[0084] In step S601, the method for regenerating the supported organic phase can be distillation separation or back-extraction separation.

[0085] In one embodiment of the present invention, step S601 employs distillation separation, and the resulting phenol product is phenol oil.

[0086] In another embodiment of the present invention, step S601 employs back-extraction separation, using a 15%~20% sodium hydroxide solution to back-extract the supported organic phase, and the resulting phenol product is sodium phenolate.

[0087] It is worth noting that because acid tar, acid pitch, and high-valence metal ions are thoroughly removed in the preceding steps, the influence of the formation of a third phase is eliminated during the extraction process in step S501 and the extractant regeneration process in step S601. This makes the extraction process more stable and greatly reduces the consumption of extractant.

[0088] The specific implementation of step S701 can be to add lime milk to the phenol-removing water, adjust the pH value of the wastewater to 7-9, and filter to remove the precipitates in the water to obtain purified water.

[0089] Embodiments of the present invention provide a system for purifying phenol- and ammonia-containing wastewater, such as... Figure 2 As shown, the system for purifying phenol-ammonia-containing wastewater includes:

[0090] A curing agent mixer is used to fully mix powdered curing agent and phenol-ammonia-containing wastewater and then feed it into the curing reactor. The curing agent mixer adopts the form of a precision pulverizing pump, and the particle size of the solid particles being pulverized / mixed is 1~50μm.

[0091] The outlet of the curing agent mixer is connected to the aqueous phase inlet of the curing reactor. The curing reactor can be one or more units connected in series. In the curing reactor, the target pollutant is cured from the aqueous phase through physical adsorption and chemical reaction. Then, it settles in the curing reactor in the form of particles and is discharged from the curing agent outlet for curing agent regeneration.

[0092] The post-curing filter is connected to the aqueous phase outlet of the curing reactor. It receives the aqueous phase discharged from the curing reactor and further intercepts tiny crystals in the wastewater with a filtration precision of 0.1~1 micrometer. The filtered slurry is returned to the curing agent mixer, and the aqueous phase becomes a pretreated liquid and goes to the first distillation column.

[0093] The curing agent regeneration reactor is used to receive the curing agent discharged from the curing reactor. Through high-temperature pyrolysis and high-temperature activation to degrade the pollutants adsorbed in the curing agent, the regenerated curing agent is returned to the curing agent mixer and the curing reactor for recycling.

[0094] The first distillation column receives the pretreated liquid from the solidified filter and removes ammonia from the wastewater through vacuum distillation. After ammonia removal, grade 1 crude phenol water is obtained. The first distillation column is equipped with a vacuum pump, and the ammonia water obtained by condensing the ammonia gas separated from the first distillation column is recovered as a by-product.

[0095] The acidification reactor is connected to the first distillation column. It receives the first-stage crude phenol water from the first distillation column. After adjusting the pH value of the phenol water by adding concentrated sulfuric acid and removing acid-insoluble matter, the second-stage crude phenol water is obtained and sent to the second distillation column. The separated acid-insoluble matter is sent to the curing agent regeneration reactor.

[0096] The second distillation column receives the second-stage crude phenolic water from the acidification reactor. Hydrogen sulfide is removed from the wastewater via vacuum distillation, yielding purified phenolic water after desulfurization. The second distillation column is equipped with a vacuum pump; the hydrogen sulfide gas separated from the second distillation column is sent for sulfur recovery.

[0097] Extraction equipment is used to process purified phenolic water. By fully mixing and separating the extractant and purified phenolic water in the extraction equipment, the phenolic compounds in the phenolic water are transferred to the extractant, resulting in dephenolized water and a loaded organic phase. The dephenolized water is then used for conditioning, and the loaded organic phase is used for extractant regeneration.

[0098] In one embodiment of the present invention, the extraction device may be a centrifugal extractor or a tower extractor.

[0099] The extractant regeneration equipment is used to process phenolic substances after they have been processed by the extraction equipment and distributed into the extractant to obtain a loaded organic phase. The phenol and extractant are separated in the extractant regeneration equipment to obtain regenerated extractant and phenol product. The regenerated extractant is then recycled back to the extraction equipment.

[0100] The dephenolized water after extraction is weakly acidic. It is then sent to the conditioning equipment where lime slurry is added to adjust the pH to 7-9. The resulting precipitate is then filtered and separated before being sent to the downstream biochemical treatment unit.

[0101] Example 1

[0102] The conditions for preparing the active curing agent are as follows:

[0103] (1) Use 50% by mass of calcium oxide, 15% by mass of zinc oxide (all of the above raw materials are ultrafine powder with a particle size <50μm), and 35% by mass of powdered activated carbon (particle size <50μm) to mix thoroughly, then add 20% water to wet it, and press it into granules with a diameter of 5mm and a length of 5~10mm at a molding pressure of 200 kN / cm2;

[0104] (2) The above granular material is activated by high-temperature heat treatment under the following conditions to obtain an activated curing agent;

[0105]

[0106] (3) The above-mentioned activating and curing agent is crushed and sieved to the following particle size distribution:

[0107]

[0108] The performance parameters of the active curing agent were analyzed when it was added to deionized water at a ratio of 5% at 50°C.

[0109]

[0110] It is evident that when active curing agents are added to water, they can form a certain proportion of dissolved and dissociated components and provide sufficient alkalinity, while most of the suspended components can provide adsorption functions.

[0111] Example 2

[0112] The wastewater containing phenols and ammonia produced by a coal tar processing enterprise has the following characteristics:

[0113]

[0114] This embodiment uses the active curing agent provided by the present invention and the method for purifying phenol-ammonia-containing wastewater using the curing agent. The specific treatment process is as follows:

[0115] (a) Pretreatment steps for removing acidified tar, alkali-insoluble matter, and suspended solids:

[0116] The active curing agent prepared in Example 1 was added to the phenol-ammonia wastewater at a ratio of 5% (by mass) of the wastewater flow rate, and the fluidized reaction was carried out for a contact time of 40 minutes.

[0117] The solid insoluble matter was separated by filtration with a filtration precision of 0.1 micrometers to obtain the pretreated solution;

[0118] The solid insoluble material was heat-treated at high temperature under the following conditions:

[0119] (1) Pressing, dehydrating and extruding the wet solid insoluble material to obtain granules with a diameter of 5 mm and a length of 5~10 mm;

[0120] (2) The above granules are regenerated by high-temperature heat treatment. The regeneration atmosphere is an oxygen-containing atmosphere (oxygen concentration 5%~60%). The heat treatment temperature is 700~900℃ for 1~2 hours. The heat treatment reaction method is rotary kiln calcination to obtain an activated curing agent.

[0121] (3) The above-mentioned activating curing agent is pulverized and sieved to the following particle size distribution to obtain the regenerated curing agent:

[0122]

[0123] The above-mentioned regenerated curing agent is recycled into the phenol-ammonia wastewater, with the amount of fresh active curing agent added being 0.5% and the remainder being regenerated curing agent, for a total curing agent dosage of 5%.

[0124] (II) Deamination Steps:

[0125] The pretreated liquid is subjected to vacuum distillation. The distillation column is a packed column with FRPP structured packing. The pressure at the top of the column is 10~15 kPaA, the temperature at the top of the column is 45℃, the pressure at the bottom of the column is 18~22 kPaA, and the temperature at the bottom of the column is 65℃. A 15% concentration of ammonia water is obtained at the top of the column, and grade 1 crude phenol water is discharged from the bottom of the column.

[0126] (III) Acidification and impurity removal steps

[0127] Add concentrated sulfuric acid to the first-grade crude phenol water, adjust the pH value to 5.5, retain for 30 minutes, and then filter with a precision of 0.1 microns to obtain the second-grade crude phenol water;

[0128] (iv) Desulfurization steps

[0129] The crude phenol water of stage 2 is subjected to vacuum stripping. The stripping tower is a packed tower with FRPP structured packing. The pressure at the top of the tower is 5~10 kPaA, the temperature at the top of the tower is 40℃, the pressure at the bottom of the tower is 15~20 kPaA, and the temperature at the bottom of the tower is 60℃. The top of the tower is a sulfur removal device rich in hydrogen sulfide gas, and the bottom of the tower discharges purified phenol water.

[0130] (v) Extraction and dephenolization steps

[0131] N,N-bis(1-methylheptyl)acetamide and No. 260 solvent oil were used as extractants in a mass ratio of 1:3. The phenol water was purified by countercurrent extraction using a six-stage centrifugal extractor. The flow ratio of wastewater to extractant was 3:1 to 2:1. The extraction operation temperature was 55℃ to 65℃. After extraction, phenol-free water and loaded organic phase were obtained.

[0132] (vi) Extractant regeneration step

[0133] A 16%–21% sodium hydroxide solution was used as the back-extraction agent to back-extract the supported organic phase. The flow ratio of the back-extraction agent to the supported organic phase was ~1:20. A three-stage centrifugal extractor was used. After the back-extraction was completed, the regenerated extractant and sodium phenolate product were obtained. The regenerated extractant was returned to the fifth step for recycling.

[0134] (vii) Conditioning and desalination steps

[0135] Lime slurry is added to the phenol-removed water obtained in step five to adjust the pH value of the wastewater to 7-9, and the water is filtered to remove the precipitate, resulting in purified water. The purified water is then sent to a biological treatment unit for further advanced treatment.

[0136] Comparative Example 1

[0137] Similarly, in Example 2, the coal tar processing wastewater containing phenols and ammonia was treated using a process where the enterprise first underwent single-tower pressurized stripping for desulfurization and ammonia removal, followed by coagulation sedimentation + flotation for oil and suspended solids removal, intermediate Fenton oxidation for phenol removal, and final iron-carbon micro-electrolysis for deep phenol removal. The treated wastewater was then sent to a biological treatment facility. Samples obtained from the enterprise's daily production were tested, and the results were used as Comparative Example 1. The treatment results of Example 2 and Comparative Example 1 were compared and analyzed. The data comparison before and after treatment in the two comparative implementation schemes is as follows:

[0138]

[0139] The following is a comparison of other technical and economic indicators between Example 2 and Comparative Example 1:

[0140]

[0141] A comparative analysis of the technical and economic indicators presented in the two tables above shows that, for phenol and ammonia wastewater containing extremely high concentrations of pollutants, compared with traditional advanced oxidation treatment processes, the technology of this invention, which employs an active curing agent for segmented and graded treatment, achieves higher removal rates for pollutants such as tar, ammonia nitrogen, sulfides, and phenols, with a phenol recovery rate exceeding 99%. Furthermore, it does not generate harmful solid waste, produces high-quality purified water, and has significantly lower operating costs per ton of water compared to advanced oxidation processes.

[0142] Example 3

[0143] The wastewater containing phenols and ammonia generated by a coal gasification project has the following characteristics:

[0144]

[0145] The project's phenol and ammonia recovery adopts air flotation and filtration for pretreatment, followed by a deacidification-deammoniation-extraction-phenol removal process, using diisopropyl ether as the extractant, which is then regenerated by distillation.

[0146] In actual production, the phenol and ammonia recovery project has problems such as high total phenol and COD in the effluent, severe fluctuations in indicators, poor pretreatment effect, high oil and suspended solids content, and easy clogging of heat exchangers, resulting in frequent shutdowns for cleaning.

[0147] In this embodiment, the above problems are addressed by using the active curing agent provided by the present invention to enhance the degreasing and impurity removal process, and a low-temperature deammoniation-precipitation deacidification process.

[0148] (1) Prepare the curing agent according to the method of Example 1 of the present invention, and adjust the curing agent ratio as follows:

[0149] The formula uses 50% calcium oxide, 25% zinc oxide (both of which are ultrafine powders with a particle size <50μm), and 25% powdered activated carbon (particle size <50μm).

[0150] (2) Process according to the method of Embodiment 2 of the present invention, and adjust some processing parameters in each operation step as follows:

[0151] (i) In the first step of pretreatment to remove acidified tar, alkali-insoluble matter, and suspended solids, the dosage of the active curing agent is adjusted to 2.5%;

[0152] (ii) In the fifth step of extraction and dephenolization, diisopropyl ether is used as the extractant, the operating temperature is adjusted to 45℃~50℃, and the volume ratio (water phase to extractant) is 6:1~4:1, and the rotary extraction tower is used for countercurrent extraction.

[0153] (iii) In the sixth step of extractant regeneration, vacuum distillation is used to separate phenolic oil from the bottom of the regeneration tower and to recycle the regenerated extractant from the top of the regeneration tower. The operating pressure of the regeneration tower is 50 kPaA~70 kPaA, the operating temperature of the bottom of the regeneration tower is 105~110℃, and the operating temperature of the top of the regeneration tower is 76~82℃.

[0154] The processing methods for the other steps are the same as those in Example 2. After the seven steps of this invention, purified water is obtained and sent to a biochemical device for further deep processing.

[0155] Water quality analysis was performed on the purified water obtained after treatment in this embodiment, and the technical and economic indicators of the implementation process were statistically analyzed. Samples obtained from daily production using the original treatment process (air flotation and filtration pretreatment, deacidification-deammoniation-extraction dephenolization process) were also tested, and the results are considered as Comparative Example 2. The relevant technical and economic indicators of Example 3 and Comparative Example 2 are statistically analyzed as follows:

[0156]

[0157] The following is a comparison of other technical and economic indicators between Example 3 and Comparative Example 2:

[0158]

[0159] Other: In Example 3, the ammonia water recovered in the second step of ammonia removal had a concentration of 16%~20%, with good product purity and almost no hydrogen sulfide or phenols. In the fourth step of hydrogen sulfide removal, the acidic gas recovered was mainly hydrogen sulfide, with almost no carbon dioxide or phenols. The main reason for the high quality of ammonia water recovery in this technology is that after the addition of the solidifying agent, the alkaline active sites of the solidifying agent combine with acidic components such as carbon dioxide, hydrogen sulfide, and phenols, solidifying them. In the hydrogen sulfide removal step, all pollutants except phenols in the wastewater have been almost completely removed. Therefore, the introduction of the active solidifying agent stabilizes specific ions at a specific stage, preventing them from interfering with the removal process of the target pollutants, thereby achieving deep, segmented, and graded treatment of pollutants such as tar, ammonia nitrogen, sulfides, and phenols.

[0160] It should be noted that, since Example 3 uses an active curing agent to enhance the removal of tar and suspended impurities from phenol-ammonia-containing wastewater, and high vacuum and low temperature operations are used in the second step of ammonia removal and the fourth step of hydrogen sulfide removal, the extremely low tar residue has a significantly reduced impact on the ammonia stripping tower and the hydrogen sulfide stripping tower. On the other hand, the low temperature operation also greatly reduces the risk of residual tar heating and coking, which can clog the tower equipment, and also greatly reduces the risk of tar clogging in the fifth step of phenol extraction. Since there is no influence from impurity acid tar, the risk of a third phase being generated during extraction, which could lead to difficulties in separating the extractant and water, as well as the risk of extractant emulsification and loss, is also eliminated. The phenol-ammonia recovery unit operates more stably and reliably.

[0161] Example 4

[0162] For the phenol-ammonia-containing wastewater described in Example 3, some operating conditions were changed while other conditions remained unchanged:

[0163] On the one hand, the extractant and extraction process of the fifth step of extraction and dephenolization were changed. 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P-507) and aviation kerosene were mixed at a volume ratio of 1:3 as the extractant. The extraction process was changed to a four-stage countercurrent extraction in a centrifugal extractor. The extraction operating temperature was 55℃~62℃ and the extraction ratio (volume ratio of aqueous phase to extractant) was 8:1~5:1.

[0164] On the other hand, the sixth step of extractant regeneration is changed to back-extraction using a 15%~20% sodium hydroxide solution. The back-extraction equipment adopts a three-stage countercurrent back-extraction centrifugal extractor. The back-extraction ratio (volume ratio of loaded extractant to back-extractant) is 10:1~6:1. A three-stage centrifugal extractor is used to complete the back-extraction, obtaining the regenerated extractant and sodium phenolate product.

[0165] The water quality analysis results of the purified water are as follows:

[0166]

[0167] The results of Example 4, compared with those of Example 3 and Comparative Example 2, show that due to the high boiling point and low solubility of the complex extractant P-507, and the fact that the partition coefficient of P-507 for both lower and higher phenols is more than 50% higher than that of physical extractants such as diisopropyl ether or methyl isobutyl ketone, a higher phenol and COD removal rate can be achieved. Moreover, the amount of extractant used is more than 50% lower than that used in Example 3 and Comparative Example 2, resulting in lower energy consumption of the device.

[0168] Meanwhile, Example 4 demonstrates the advantages of the device in long-term operation, such as no scaling or clogging, high purity and quality of by-products, and low extractant loss, due to the early and deep removal of tar and suspended solids.

[0169] In summary, this invention addresses the stable state of multiphase coexistence of various pollutants such as acid tar, suspended solids, ammonia nitrogen, sulfides, and phenols in general phenol and ammonia wastewater. It utilizes an active curing agent to deeply remove acid tar and acid bitumen, which significantly negatively impact the stable operation and treatment efficiency of the equipment, through physical and chemical adsorption. The active ions released by the curing agent stabilize the interfering phase, improving the separation performance of the target pollutants. This segmented and graded approach achieves highly efficient removal of the main pollutants, resulting in better performance in terms of reliability, energy efficiency, and treatment depth in the treatment of phenol and ammonia wastewater.

[0170] The foregoing description illustrates and describes several preferred embodiments of the invention. However, as previously stated, it should be understood that the invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the invention should be within the protection scope of the appended claims.

[0171] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and incorporate common knowledge or customary techniques in the art disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this application is indicated by the claims.

[0172] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The embodiments of this application described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A method for purifying phenol-ammonia-containing wastewater using an active curing agent, characterized in that, Includes the following steps: S101: Add an active curing agent to the phenol-ammonia-containing wastewater and control the water phase temperature at 45~60℃, control the pH value of the phenol-ammonia-containing wastewater at 9~11, and then filter to remove the solid phase to obtain a pretreated liquid. S201: The pretreatment liquid is subjected to deammoniation treatment to obtain ammonia water product and grade 1 crude phenol water; S301: Add concentrated sulfuric acid to the first-grade crude phenol water to adjust the pH value to 4.5~6.5, and then remove the insoluble matter precipitated therein to obtain the second-grade crude phenol water; S401: The second-stage crude phenol water is subjected to hydrogen sulfide removal treatment to obtain purified phenol water; S501: Extract the purified phenolic water using an organic extractant to obtain dephenolized water and a supported organic phase; S601: Phenol is recovered from the supported organic phase to obtain a phenol product, and a regenerated extractant is obtained and returned to the purified phenol water for recycling.

2. The method for purifying phenol-ammonia-containing wastewater according to claim 1, characterized in that, The method for preparing the active curing agent is as follows: (1) Use 40%~70% by mass of alkaline oxide ultrafine powder with a particle size of less than 50μm, 5%~10% by mass of zinc oxide and 30%~60% by mass of powdered activated carbon, mix thoroughly, then add 10%~30% by mass of water to wet, and press into granules with a diameter of 3~6mm and a length of 5~10mm at a molding pressure of 100-200 kN / cm2; (2) The granular material is activated by high-temperature heat treatment to obtain an activated curing agent: ① In the temperature range of room temperature to 200℃, the temperature is increased at a rate of 5 to 10℃ / minute. After the temperature reaches 200℃, it is held for 50 to 100 minutes. The operating pressure is -5 to 10 kPaG. The atmosphere is air. When the material temperature is >110℃, air is supplied. The ratio of the volume of purging air (Nm3 / h) to the volume of granular material (m3 / h) is 3 to 15. ② Increase the temperature at a rate of 8~12℃ / minute within the temperature range of 200~600℃. After the temperature reaches 600℃, maintain the temperature for 30~60 minutes. The operating pressure is -5~10KPaG. The atmosphere is ammonia. The gas is supplied evenly throughout the process, with the gas supply ratio being 3~10 times the volume of purging gas (Nm3 / h) to the volume of granular material (m3 / h). ③ Increase the temperature at a rate of 8-12℃ / minute within the temperature range of 600-800℃. After reaching 800℃, hold the temperature for 20-30 minutes. The operating pressure is -5-10KPaG, and the atmosphere is oxygen-free. ④ Physically cool the heat-treated material to room temperature ~ 90℃; (3) The activated curing agent is pulverized and sieved to the following particle size distribution: The mass percentage of particles with a diameter of 100~200μm is 10%, the mass percentage of particles with a diameter of 50~100μm is 60%, the mass percentage of particles with a diameter of 30~50μm is 15%, and the mass percentage of particles with a diameter of <30μm is 15%.

3. The method for purifying phenol-ammonia-containing wastewater according to claim 2, characterized in that, The saturated active curing agent is regenerated to restore its active sites and then recycled. The method for regenerating the active curing agent is as follows: (1) The active curing agent is filtered out from the water to obtain wet material; (2) The wet material is pressed, dehydrated and extruded to obtain granules with a diameter of 3-6 mm and a length of 5-10 mm; (3) The granules are subjected to high-temperature calcination at a temperature of 700-900°C. At the same time as calcination, a gas with an oxygen concentration of 5%-60% is introduced. After reaching the calcination temperature, the calcination treatment time is 1-2 hours to obtain a regenerated active curing agent. (4) The regenerated curing agent is crushed and sieved to the following particle size distribution: The mass percentage of particles with a diameter of 100-200μm is 10%, the mass percentage of particles with a diameter of 50-100μm is 60%, the mass percentage of particles with a diameter of 30-50μm is 15%, and the mass percentage of particles with a diameter of less than 30μm is 15%.

4. The method for purifying phenol-ammonia-containing wastewater according to claim 3, characterized in that, The active curing agent adsorbs impurities in the phenol-ammonia-containing wastewater through its surface alkaline active sites and active ions. The adsorption process is in a liquid-solid fluidized state or a suspended state. The proportion of the curing agent in the wastewater is 0.5% to 5%, and the residence time of the adsorption process is 0.5 hours to 2 hours.

5. The method for purifying phenol-ammonia-containing wastewater according to claim 4, characterized in that, The regenerated active curing agent is used in a ratio of 1:2 to 1:

5.

6. The method for purifying phenol-ammonia-containing wastewater according to claim 1, characterized in that, The ammonia removal process is a vacuum ammonia stripping operation, with an operating temperature of 50~80℃ and an operating pressure of 5KPaA~20KPaA.

7. The method for purifying phenol-ammonia-containing wastewater according to claim 5, characterized in that, The acid-insoluble substance is added to the pressing, dehydration, and extrusion molding processes and thoroughly mixed with the active curing agent.

8. The method for purifying phenol-ammonia-containing wastewater according to claim 1, characterized in that, The desulfurization treatment method is vacuum stripping or vacuum distillation, with an operating temperature of 50~80℃ and an operating pressure of 5KPaA~20KPaA.

9. The method for purifying phenol-ammonia-containing wastewater according to claim 1, characterized in that, The extractant includes any one or a combination of N,N-bis(1-methylheptyl)acetamide, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester and aviation kerosene, methyl isobutyl ketone, diisopropyl ether, methyl tert-butyl ketone, butyl acetate.

10. The method for purifying phenol-ammonia-containing wastewater according to claim 1, characterized in that, The phenol-removed water is adjusted to pH 7-8 using lime milk and then filtered to remove the generated precipitate to obtain purified water.

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