A method for treating phenolic wastewater

Abstract

The present application relates to the technical field of phenol-containing wastewater treatment, and discloses a method for treating phenol-containing wastewater, which comprises the following steps: (1) mixing powdered active coke with an alkaline solution, washing and drying the obtained primary product to obtain an intermediate; (2) performing microwave irradiation on the intermediate in a protective gas atmosphere to obtain modified active coke; (3) feeding the phenol-containing wastewater into a first adsorption and precipitation device, mixing the wastewater with the modified active coke, and performing solid-liquid separation; (4) feeding the liquid phase separated in step (3) into a second adsorption and precipitation device, mixing the liquid phase with the modified active coke, and performing solid-liquid separation; (5) feeding the liquid phase separated in step (4) into a third adsorption and precipitation device, mixing the liquid phase with the modified active coke, and then performing solid-liquid separation to obtain the wastewater after deep treatment. The method provided by the present application can effectively remove phenolic compounds in the phenol-containing wastewater, and the treatment cost is low.

Description

Technical Field

[0001] This invention relates to the field of phenol-containing wastewater treatment technology, and specifically to a method for treating phenol-containing wastewater. Background Technology

[0002] Phenol is an important organic chemical raw material and a common, recalcitrant, and highly toxic organic compound in wastewater. Characterized by its high toxicity and difficulty in degradation, it has become a significant source of pollution for major water bodies. Given the increasingly stringent limits on water pollutant discharge, it is necessary to conduct advanced treatment of phenol-containing wastewater to further reduce its concentration, ensuring compliance with discharge standards and preventing pollution-related poisoning incidents.

[0003] Currently, activated carbon is the most commonly used material for treating phenol-containing wastewater. However, the high cost of powdered activated carbon raw materials, complicated manufacturing process, and high price limit its widespread application in advanced wastewater treatment.

[0004] Powdered activated coke possesses the characteristics of activated carbon, but its production cost is far lower. It is a porous adsorbent carbon solid material made primarily from coal and other raw materials. Powdered activated coke has been widely used in the field of air pollution control, but its application in the treatment of phenol-containing wastewater is limited and its effectiveness is poor. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high cost of powdered activated carbon and poor effect of powdered activated coke in treating phenol-containing wastewater in the prior art, and to provide a method for treating phenol-containing wastewater.

[0006] To achieve the above objectives, the present invention provides a method for treating phenol-containing wastewater, the method comprising the following steps:

[0007] (1) Mix powdered activated coke with an alkaline solution, wash and dry the resulting primary product to obtain an intermediate product;

[0008] (2) The intermediate was microwave irradiated under a protective gas atmosphere to obtain modified activated char;

[0009] (3) The phenol-containing wastewater is transported to a primary adsorption and precipitation device, mixed with the modified activated carbon, and then separated into solid and liquid components.

[0010] (4) The liquid phase obtained in step (3) is transported to a secondary adsorption precipitation device, mixed with the modified activated carbon, and then separated into solid and liquid phases;

[0011] (5) The liquid phase obtained in step (4) is transported to a three-stage adsorption precipitation device, mixed with the modified activated carbon, and then separated into solid and liquid phases to obtain the wastewater after deep treatment.

[0012] The solid phase separated in step (5) is recycled to the secondary adsorption-precipitation device in step (4). The solid phase separated in step (4) is recycled to the primary adsorption-precipitation device in step (3).

[0013] Preferably, in step (1), the alkaline solution is a potassium hydroxide solution and / or a sodium hydroxide solution.

[0014] Preferably, in step (1), the concentration of the alkaline solution is 0.5 to 3 mol / L.

[0015] Preferably, in step (1), the mass ratio of the powdered activated coke to the alkaline solution is 1:5 to 25.

[0016] Preferably, in step (1), the mixing time is 10 to 25 hours.

[0017] Preferably, in step (1), the drying temperature is 70 to 100°C.

[0018] Preferably, in step (1), the particle size of the powdered activated coke is ≤100 mesh.

[0019] Preferably, in step (1), the particle size of the powdered activated coke is ≤200 mesh.

[0020] Preferably, in step (2), the protective gas is nitrogen.

[0021] Preferably, in step (2), the power of the microwave irradiation is 500-1000W and the time is 5-15min.

[0022] Compared with the prior art, the method for treating phenol-containing wastewater described in this invention has the following advantages:

[0023] (1) By modifying powdered activated coke with alkali and microwave, the active adsorption sites on the surface of powdered activated coke are increased, and the specific surface area and pore structure are further expanded, thereby improving its adsorption and removal capacity for phenol-containing wastewater. At the same time, the modified activated coke has low cost, so it can be well applied to the field of deep treatment of phenol-containing wastewater.

[0024] (2) In this invention, the modified activated carbon is used in a three-stage adsorption-precipitation device, a two-stage adsorption-precipitation device and a one-stage adsorption-precipitation device in sequence. By using the three-stage countercurrent adsorption method, the adsorption capacity of the modified activated carbon can be fully utilized, thereby reducing the amount of modified activated carbon used and thus reducing the cost of wastewater treatment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a system for implementing an embodiment of the method for treating phenol-containing wastewater provided by the present invention;

[0026] Figure 2 These are the Fourier transform infrared spectra of the powdered activated carbon and the modified activated carbon in Example 1 of this invention;

[0027] Figure 3 This is a 2μm resolution SEM image of the powdered activated coke in Example 1 of the present invention;

[0028] Figure 4 This is a 2μm resolution SEM image of the modified activated carbon in Example 1 of this invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1- Primary adsorption tank; 2- Primary sedimentation tank; 3- Secondary adsorption tank; 4- Secondary sedimentation tank; 5- Tertiary adsorption tank; 6- Tertiary sedimentation tank; 7- Regeneration device; 8- Automatic feeder. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. 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.

[0033] This invention proposes a method for treating phenol-containing wastewater. The method is implemented in a system comprising a primary adsorption-precipitation device, a secondary adsorption-precipitation device, and a tertiary adsorption-precipitation device. The method includes the following steps:

[0034] (1) Mix powdered activated coke with an alkaline solution, wash and dry the resulting primary product to obtain an intermediate product;

[0035] (2) The intermediate was microwave irradiated under a protective gas atmosphere to obtain modified activated char;

[0036] (3) The phenol-containing wastewater is transported to a primary adsorption and precipitation device, mixed with the modified activated carbon located therein, and then separated into solid and liquid components.

[0037] (4) The liquid phase obtained in step (3) is transported to a secondary adsorption precipitation device and mixed with the modified activated carbon located therein, and then the solid and liquid are separated.

[0038] (5) The liquid phase obtained in step (4) is transported to a three-stage adsorption precipitation device and mixed with the modified activated carbon located therein. Then, solid-liquid separation is performed to obtain the deeply treated wastewater.

[0039] In a preferred embodiment, in step (1), the particle size of the powdered activated carbon is ≤100 mesh, preferably ≤200 mesh, and more preferably ≤230 mesh, so that the modified activated carbon obtained has better adsorption performance.

[0040] By mixing powdered activated carbon with an alkaline solution, impurities on the surface or in the pores of the powdered activated carbon can be dissolved or removed, thereby increasing the pore volume and specific surface area of ​​the powdered activated carbon. Furthermore, the number of alkaline functional groups on the surface of the powdered activated carbon can be increased, thereby enhancing its adsorption capacity for phenolic organic compounds. In a preferred embodiment, in step (1), the alkaline solution is a potassium hydroxide solution and / or a sodium hydroxide solution, preferably a potassium hydroxide solution.

[0041] In a preferred embodiment, the powdered activated coke is pretreated before use. The pretreatment steps include: washing the powdered activated coke three times with ultrapure water (resistivity ≥18MΩ·cm), drying it at 55-105°C, and then passing it through a 100-230 mesh sieve.

[0042] In a preferred embodiment, in step (1), the concentration of the alkaline solution is 0.5 to 3 mol / L, specifically, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 1.7 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L.

[0043] In a preferred embodiment, in step (1), the mass ratio of the powdered activated coke to the alkaline solution is 1:5 to 25, more preferably 1:8 to 15, so that the alkaline solution can immerse the powdered activated coke and the modification effect is better.

[0044] In a preferred embodiment, in step (1), the mixing time is 10 to 25 hours, preferably 10 to 20 hours.

[0045] In a preferred embodiment, in step (1), the drying temperature is 70–100°C.

[0046] In a preferred embodiment, step (1) specifically includes: mixing powdered activated coke with an alkaline solution until uniform, then shaking and impregnating for 10-25 hours, washing the resulting initial product (impregnated powdered activated coke) with ultrapure water until the pH value of the aqueous solution no longer changes, and then drying to constant weight.

[0047] In this invention, by subjecting the intermediate to microwave irradiation treatment, the pore structure and surface chemical properties of the powdered activated coke can be altered, thereby further improving the adsorption effect of the powdered activated coke on phenolic organic compounds.

[0048] In a preferred embodiment, in step (2), the power of the microwave irradiation is 500-1000W and the time is 5-15min.

[0049] In a preferred embodiment, in step (2), the protective gas is nitrogen.

[0050] In specific implementation, step (2) includes: placing the intermediate in a U-shaped quartz tube under a protective gas atmosphere and irradiating it with microwaves in a 500-1000W microwave oven for 5-15 minutes.

[0051] In the method described in this invention, the concentration of phenolic organic matter in the phenol-containing wastewater is highest in the primary adsorption-precipitation device, followed by the liquid phase in the secondary adsorption-precipitation device and then the liquid phase in the tertiary adsorption-precipitation device. Therefore, after the modified activated carbon becomes saturated with phenolic organic matter in the tertiary adsorption-precipitation device, it can still enter the secondary adsorption-precipitation device to continue adsorbing phenolic organic matter; similarly, the modified activated carbon that has become saturated in the secondary adsorption-precipitation device can be transported to the primary adsorption-precipitation device for further adsorption.

[0052] In a preferred embodiment, the solid phase (i.e., modified activated carbon) separated in step (5) is recycled to the secondary adsorption precipitation device in step (4), and the solid phase (i.e., modified activated carbon) separated in step (4) is recycled to the primary adsorption precipitation device in step (3), thereby giving full play to the adsorption capacity of the modified activated carbon.

[0053] In the method described in this invention, phenol-containing wastewater is treated using a three-stage countercurrent adsorption method, which can fully utilize the adsorption capacity of modified activated carbon, reduce the amount of modified activated carbon used, and thus reduce wastewater treatment costs.

[0054] In a preferred embodiment, phenol-containing wastewater is sequentially treated in a primary adsorption-precipitation device, a secondary adsorption-precipitation device, and a tertiary adsorption-precipitation device, and finally discharged as effluent; modified activated carbon is added to the tertiary adsorption-precipitation device, and after adsorption and precipitation, it enters the secondary adsorption-precipitation device, and after adsorption and precipitation, it finally enters the primary adsorption-precipitation device.

[0055] In this invention, the primary adsorption-precipitation device, the secondary adsorption-precipitation device, and the tertiary adsorption-precipitation device can be carried out in one reaction tank, simultaneously performing adsorption and separation functions; or they can be carried out in two reaction tanks, respectively performing adsorption and separation functions. Preferably, there are two reaction tanks, namely an adsorption tank and a precipitation tank.

[0056] Please refer to the following: Figure 1 (In the figure, the solid line represents the flow direction of phenol-containing wastewater, and the dashed line represents the circulation direction of powdered activated coke.) In a preferred embodiment, the primary adsorption and sedimentation device includes a primary adsorption tank 1 and a primary sedimentation tank 2, the secondary adsorption and sedimentation device includes a secondary adsorption tank 3 and a secondary sedimentation tank 4, and the tertiary adsorption and sedimentation device includes a tertiary adsorption tank 5 and a tertiary sedimentation tank 6.

[0057] In a preferred embodiment, step (3) specifically includes:

[0058] The phenol-containing wastewater is transported to the primary adsorption tank 1, where it is mixed and stirred with modified activated carbon to ensure that the modified activated carbon can fully adsorb the phenolic organic matter in the phenol-containing wastewater. Then, it is transported to the primary sedimentation tank 2 for natural sedimentation to achieve solid-liquid separation.

[0059] In a preferred embodiment, step (4) specifically includes:

[0060] The liquid phase obtained in step (3) is transported to the secondary adsorption tank 3, mixed and stirred with the modified activated coke, and then transported to the secondary sedimentation tank 4 for natural sedimentation.

[0061] In a preferred embodiment, step (5) specifically includes:

[0062] The liquid phase obtained in step (4) is transported to the tertiary adsorption tank 5, mixed and stirred with modified activated coke, and then transported to the tertiary sedimentation tank 6 for natural sedimentation.

[0063] In a preferred embodiment, the method for treating phenol-containing wastewater includes the following steps:

[0064] (1) Mix powdered activated coke with an alkaline solution, wash and dry the resulting primary product to obtain an intermediate product;

[0065] (2) The intermediate was microwave irradiated under a protective gas atmosphere to obtain modified activated char;

[0066] (3) The phenol-containing wastewater is transported to the primary adsorption tank 1 and mixed with the modified activated carbon located therein, and then the solid and liquid are separated in the primary sedimentation tank 2.

[0067] (4) The liquid phase obtained in step (3) is transported to the secondary adsorption tank 3 and mixed with the modified activated carbon located therein, and then solid-liquid separation is performed in the secondary sedimentation tank 4.

[0068] (5) The liquid phase obtained in step (4) is transported to the three-stage adsorption tank 5 and mixed with the modified activated carbon located therein. Then, solid-liquid separation is performed in the three-stage sedimentation tank 6 to obtain the wastewater after deep treatment.

[0069] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, then settled in the three-stage sedimentation tank 6, and then enters the two-stage adsorption tank 3 for adsorption, the two-stage sedimentation tank 4 for sedimentation, and finally enters the one-stage adsorption tank 1 for adsorption and the one-stage sedimentation tank 2 for sedimentation.

[0070] In a preferred embodiment, the adsorption time in the primary adsorption tank 1, the secondary adsorption tank 3, and the tertiary adsorption tank 5 is controlled between 0.2 and 2 hours.

[0071] In a preferred embodiment, a stirrer is provided in the primary adsorption tank 1, the secondary adsorption tank 3, and the tertiary adsorption tank 5.

[0072] In a preferred embodiment, the sedimentation time in the primary sedimentation tank 2, the secondary sedimentation tank 4, and the tertiary sedimentation tank 6 is controlled to be 1 to 3 hours.

[0073] In a preferred embodiment, the modified activated coke is quantitatively added using an automatic feeder 8. The amount added is mainly determined based on the amount of phenols in the wastewater. The modified activated coke addition point is located in the stirring tank of the tertiary adsorption tank 5.

[0074] In a preferred embodiment, the amount of modified activated coke added per ton of phenol-containing wastewater is 1.0 to 3.0 kg.

[0075] In a preferred embodiment, a regeneration device 7 is provided between the primary adsorption precipitation device and the tertiary adsorption precipitation device. The regeneration device 7 is used to regenerate the solid phase from the primary adsorption precipitation device to obtain regenerated activated carbon, which is then transported to the tertiary adsorption precipitation device for reuse.

[0076] More preferably, the regeneration device 7 is a regeneration furnace.

[0077] In a preferred embodiment, a drying device is further provided between the primary adsorption precipitation device and the regeneration device 7 for drying the activated carbon from the primary adsorption precipitation device.

[0078] In the method described in this invention, the adsorption capacity of powdered activated carbon for phenolic organic compounds is improved by modifying the powdered activated carbon. Simultaneously, the adsorption capacity of the modified activated carbon is fully utilized through a three-stage countercurrent adsorption process, reducing the amount of modified activated carbon required. Therefore, the method provided by this invention can effectively treat phenol-containing wastewater with low treatment costs.

[0079] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto. The following examples refer to… Figure 1 The process shown is as follows.

[0080] In the following example, before use, the powdered activated coke is washed three times with ultrapure water (resistivity ≥18MΩ·cm), dried at 85℃, and then passed through a 230-mesh sieve to obtain powdered activated coke with a particle size ≤230 mesh.

[0081] Example 1

[0082] This embodiment illustrates the method for treating phenol-containing wastewater provided by the present invention.

[0083] (1) Powdered activated coke with a particle size ≤230 mesh was mixed with 2 mol / L KOH solution at a mass ratio of 1:10. The mixture was then placed in a constant temperature shaker (25℃) for constant temperature shaking. After shaking and soaking for 20 h, the initial product was washed with ultrapure water until the pH value of the aqueous solution no longer changed. Then it was dried at 85℃ to constant weight to obtain the intermediate.

[0084] (2) Under a nitrogen atmosphere, the intermediate was placed in a U-shaped quartz tube and microwaved in a 700W microwave oven for 10 minutes, then cooled to obtain modified activated char.

[0085] (3) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with modified activated carbon and stirred for 30 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 2 h for solid-liquid separation.

[0086] (4) The liquid phase separated in step (3) is transported to the secondary adsorption tank 3, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h.

[0087] (5) The liquid phase separated in step (4) is transported to the three-stage adsorption tank 5, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the three-stage sedimentation tank 6 for 2 h to obtain the wastewater after deep treatment.

[0088] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0089] Example 2

[0090] This embodiment illustrates the method for treating phenol-containing wastewater provided by the present invention.

[0091] (1) Powdered activated coke with a particle size ≤230 mesh was mixed with 1 mol / L KOH solution at a mass ratio of 1:10. The mixture was then placed in a constant temperature shaker (25℃) for constant temperature shaking. After shaking and soaking for 20 h, the initial product was washed with ultrapure water until the pH value of the aqueous solution no longer changed. Then it was dried at 80℃ to constant weight to obtain the intermediate.

[0092] (2) Under a nitrogen atmosphere, the intermediate was placed in a U-shaped quartz tube and microwaved in a 600W microwave oven for 12 minutes, then cooled to obtain modified activated char.

[0093] (3) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with modified activated carbon and stirred for 30 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 2 h for solid-liquid separation.

[0094] (4) The liquid phase separated in step (3) is transported to the secondary adsorption tank 3, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h.

[0095] (5) The liquid phase separated in step (4) is transported to the three-stage adsorption tank 5, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the three-stage sedimentation tank 6 for 2 h to obtain the wastewater after deep treatment.

[0096] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0097] Example 3

[0098] This embodiment illustrates the method for treating phenol-containing wastewater provided by the present invention.

[0099] (1) Powdered activated coke with a particle size ≤230 mesh was mixed with 1.5 mol / L KOH solution at a mass ratio of 1:15. The mixture was then placed in a constant temperature shaker (25℃) for constant temperature shaking. After shaking and soaking for 20 h, the initial product was washed with ultrapure water until the pH value of the aqueous solution no longer changed. Then it was dried at 80℃ to constant weight to obtain the intermediate product.

[0100] (2) Under a nitrogen atmosphere, the intermediate was placed in a U-shaped quartz tube and microwaved in a 900W microwave oven for 7 minutes, then cooled to obtain modified activated char.

[0101] (3) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with modified activated carbon and stirred for 30 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 2 h for solid-liquid separation.

[0102] (4) The liquid phase separated in step (3) is transported to the secondary adsorption tank 3, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h.

[0103] (5) The liquid phase separated in step (4) is transported to the tertiary adsorption tank 5, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h to obtain the wastewater after deep treatment.

[0104] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0105] Example 4

[0106] This embodiment illustrates the method for treating phenol-containing wastewater provided by the present invention.

[0107] (1) Powdered activated coke with a particle size ≤230 mesh was mixed with 2 mol / L KOH solution at a mass ratio of 1:10. The mixture was then placed in a constant temperature shaker (25℃) for constant temperature shaking. After shaking and soaking for 20 h, the initial product was washed with ultrapure water until the pH value of the aqueous solution no longer changed. Then it was dried at 85℃ to constant weight to obtain the intermediate.

[0108] (2) Under a nitrogen atmosphere, the intermediate was placed in a U-shaped quartz tube and microwaved in a 700W microwave oven for 10 minutes, then cooled to obtain modified activated char.

[0109] (3) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with modified activated carbon and stirred for 40 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 3 h to achieve solid-liquid separation.

[0110] (4) The liquid phase separated in step (3) is transported to the secondary adsorption tank 3, mixed with modified activated carbon and stirred for 40 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 3 h.

[0111] (5) The liquid phase separated in step (4) is transported to the tertiary adsorption tank 5, mixed with modified activated coke and stirred for 40 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 3 h to obtain the wastewater after deep treatment.

[0112] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0113] Comparative Example 1

[0114] The method described in Example 1 was implemented, except that no microwave irradiation treatment was performed.

[0115] Specifically, the method for treating phenol-containing wastewater includes the following steps:

[0116] (1) Powdered activated coke with a particle size ≤230 mesh was mixed with 2 mol / L KOH solution at a mass ratio of 1:10. The mixture was then placed in a constant temperature shaker (25℃) for constant temperature shaking. After shaking and soaking for 20 h, the initial product was washed with ultrapure water until the pH value of the aqueous solution no longer changed. Then it was dried at 85℃ to constant weight to obtain modified activated coke.

[0117] (2) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 2 h for solid-liquid separation.

[0118] (3) The liquid phase separated in step (2) is transported to the secondary adsorption tank 3, mixed with modified activated carbon and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h.

[0119] (4) The liquid phase separated in step (3) is transported to the three-stage adsorption tank 5, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the three-stage sedimentation tank 6 for 2 h to obtain the wastewater after deep treatment.

[0120] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0121] Comparative Example 2

[0122] The method described in Example 1 was implemented, except that the powdered activated coke was not subjected to alkali modification treatment.

[0123] Specifically, the method for treating phenol-containing wastewater includes the following steps:

[0124] (1) Under a nitrogen atmosphere, powdered activated coke with a particle size ≤230 mesh was placed in a U-shaped quartz tube and microwaved in a 700W microwave oven for 10 minutes, then cooled to obtain modified activated coke.

[0125] (2) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 2 h for solid-liquid separation.

[0126] (3) The liquid phase separated in step (2) is transported to the secondary adsorption tank 3, mixed with modified activated carbon and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h.

[0127] (4) The liquid phase separated in step (3) is transported to the tertiary adsorption tank 5, mixed with modified activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h to obtain the wastewater after deep treatment.

[0128] The modified activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0129] Comparative Example 3

[0130] The method described in Example 1 was implemented, except that powdered activated coke with a particle size ≤230 mesh was used directly to treat the phenol-containing wastewater.

[0131] Specifically, the method for treating phenol-containing wastewater includes the following steps:

[0132] (1) Phenolic wastewater (1500 mg / L) is transported to the primary adsorption tank 1, mixed with powdered activated coke and stirred for 30 min, and then allowed to settle naturally in the primary sedimentation tank 2 for 2 h for solid-liquid separation.

[0133] (2) The liquid phase obtained in step (1) is transported to the secondary adsorption tank 3, mixed with powdered activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h.

[0134] (3) The liquid phase separated in step (2) is transported to the tertiary adsorption tank 5, mixed with powdered activated coke and stirred for 30 min, and then allowed to settle naturally in the secondary sedimentation tank 4 for 2 h to obtain the wastewater after deep treatment.

[0135] Powdered activated coke is added to the three-stage adsorption tank 5 for adsorption, with an addition amount of 2 kg activated coke / ton of phenol-containing wastewater. After sedimentation in the three-stage sedimentation tank 6, it enters the two-stage adsorption tank 3 and the two-stage sedimentation tank 4 for adsorption and sedimentation in sequence, and finally enters the one-stage adsorption tank 1 and the one-stage sedimentation tank 2.

[0136] Test Example 1

[0137] (1) Fourier transform infrared spectroscopy analysis was performed on the powdered activated carbon in Example 1 and the prepared modified activated carbon. The results are as follows: Figure 2 As shown.

[0138] Depend on Figure 2 It can be seen that the modified activated carbon at 1600 cm⁻¹ -1 The presence of strong absorption peaks indicates the presence of more carboxyl-COO- vibrational peaks.

[0139] (2) The powdered activated carbon (before modification) and the modified activated carbon (after modification) in Example 1 were characterized using scanning electron microscopy (SEM), and the results are as follows: Figure 3 (Powdered activated carbon) and Figure 4 (Modified activated carbon) is shown.

[0140] Depend on Figure 3-4 It can be seen that the powdered activated carbon (before modification) has a well-developed pore structure with neatly arranged pores resembling a honeycomb; the surface pore structure of the modified activated carbon (after modification) becomes irregular, filled with pores of different sizes and shapes, forming a large number of microporous structures, which is conducive to adsorption.

[0141] Test Example 2

[0142] The content of phenolic substances in the phenolic wastewater after deep treatment obtained in Examples 1-4 and Comparative Examples 1-3 was detected, and the removal rate was calculated. The results are shown in Table 1.

[0143] Table 1

[0144] project Removal rate / % Example 1 87.6 Example 2 85.3 Example 3 84.9 Example 4 87.8 Comparative Example 1 78.5 Comparative Example 2 76.2 Comparative Example 3 70.4

[0145] As can be seen from the results in Table 1, the method provided by the present invention can effectively remove phenolic substances from phenol-containing wastewater.

[0146] Meanwhile, a comparison of Example 1 and Comparative Examples 1-3 shows that by modifying the powdered activated coke, the adsorption and removal capacity of the powdered activated coke for phenolic substances can be greatly improved.

[0147] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method of treating phenolic-containing wastewater, characterized by, The method comprises the following steps: (1) mixing powdered active coke with an alkaline solution, washing and drying the obtained primary product to obtain an intermediate; (2) subjecting the intermediate to microwave irradiation under a protective gas atmosphere to obtain modified active coke; (3) feeding the phenolic wastewater into a first adsorption and precipitation device and mixing with the modified active coke, and then solid-liquid separation; (4) feeding the liquid phase separated in step (3) into a second adsorption and precipitation device and mixing with the modified active coke, and then solid-liquid separation; (5) feeding the liquid phase separated in step (4) into a third adsorption and precipitation device and mixing with the modified active coke, and then solid-liquid separation to obtain the deeply treated wastewater; wherein the solid phase separated in step (5) is reused in the second adsorption and precipitation device of step (4), and the solid phase separated in step (4) is reused in the first adsorption and precipitation device of step (3); In step (2), the protective gas is nitrogen, the power of microwave irradiation is 500-1000 W, and the time is 5-15 min.

2. The method of claim 1, wherein, In step (1), the alkaline solution is potassium hydroxide solution and / or sodium hydroxide solution.

3. The method of claim 1, wherein, In step (1), the concentration of the alkaline solution is 0.5-3 mol / L.

4. The method according to any one of claims 1 to 3, characterized in that, In step (1), the mass ratio of the powdered active coke to the alkaline solution is 1:5-25.

5. The method of claim 1, wherein, In step (1), the mixing time is 10-25 h.

6. The method of claim 1, wherein, In step (1), the drying temperature is 70-100℃.

7. The method of claim 1, wherein, In step (1), the particle size of the powdered active coke is ≤100 mesh.

8. The method according to claim 1 or 7, characterized in that, In step (1), the particle size of the powdered active coke is ≤200 mesh.

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