A method and system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled membrane process

Abstract

The present application relates to the technical field of industrial wastewater treatment, and particularly relates to a method and system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled membrane process. The present application first filters petrochemical wastewater to obtain pretreated petrochemical wastewater; the pretreated petrochemical wastewater is subjected to primary adsorption treatment to obtain primary adsorption effluent, wherein the adsorbent used in the primary adsorption treatment is activated carbon; the primary adsorption effluent is subjected to secondary adsorption treatment to obtain secondary adsorption effluent, wherein the adsorbent used in the secondary adsorption treatment is silica gel; the secondary adsorption effluent is subjected to membrane separation by nanofiltration membrane to obtain effluent. The method can deeply remove pollutants in petrochemical wastewater, realizes separation of main pollutants in petrochemical wastewater, and the effluent quality is stable. The method is simple, the treatment process is controllable, and the TOC content in the effluent obtained after treatment is less than 20 ppm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial wastewater treatment, and particularly relates to a method and system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled with membrane process. BACKGROUND

[0002] Petrochemical wastewater refers to wastewater generated in the production process of petrochemical industry, oil refining, coal chemical industry, etc., which contains a large amount of particulate matter, hydrophobic / hydrophilic organic matter, heavy metals and salts and other pollutants. The high content of toxic pollutants and surfactants in petrochemical wastewater leads to low efficiency of conventional treatment, which is difficult to meet the discharge requirements. At present, oil removal by air flotation and coagulation sedimentation have been widely used in the preliminary treatment of petrochemical wastewater, but the above processes can only remove part of the emulsified oil, surface oil and volatile organic matter, etc. which are difficult to dissolve in water and have large size, and the removal rate of dissolved pollutants is still low. Fenton, ozone, electrochemistry or catalysis and other advanced oxidation technologies can significantly improve the biodegradability of petrochemical wastewater by oxidizing organic pollutants, but the high cost and the disposal problem of toxic sludge limit its application. Anaerobic or acidification oxidation and other biological treatments can produce strong removal effect on high-toxicity pollutants in petrochemical wastewater, but the operation conditions are strict and the overall time-consuming is long.

[0003] Adsorption, as a high-efficiency technology for removing pollutants in wastewater, has strong adaptability in removing dissolved organic matter and particulate matter at the same time. Activated carbon or silica gel and other adsorbents can effectively enrich and separate hydrophobic or hydrophilic pollutants in wastewater, and the above materials have the advantages of low cost, easy to control, etc. There are many types of dissolved organic matter in petrochemical wastewater, which leads to the existence of adsorption competition or adsorption promotion among pollutants. Limited by hydrophobicity and pore size, a single adsorbent is difficult to effectively remove various types of pollutants in petrochemical wastewater, and the removal of residual pollutants in adsorption effluent is still a technical challenge. Nanofiltration membrane method is a membrane separation method between ultrafiltration and reverse osmosis, which is suitable for removing pollutants with relative molecular weight above 100. Nanofiltration membrane method can effectively separate large-particle hydrophobic organic matter and salt, and is widely used in the field of petrochemical wastewater treatment. However, nanofiltration membrane method has high requirements for the quality of water, and turbidity, suspended solids, oil droplets, silicates and other nano-sized particles in water can easily block the membrane pores or form a fouling layer on the membrane surface, which affects the overall operation. Therefore, how to provide an efficient and stable method and system for deep treatment of petrochemical wastewater is still a problem to be solved in the field. SUMMARY

[0004] The present application aims to provide a method and system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled with membrane process, which can efficiently remove pollutants in petrochemical wastewater.

[0005] In order to achieve the above application purpose, the present application provides the following technical solutions:

[0006] The application provides a method for deep treatment of petrochemical wastewater based on a hierarchical adsorption coupling membrane process, comprising the following steps:

[0007] 1) filtering petrochemical wastewater to obtain pretreated petrochemical wastewater;

[0008] 2) performing primary adsorption treatment on the pretreated petrochemical wastewater to obtain primary adsorption effluent, wherein the adsorbent used in the primary adsorption treatment is activated carbon;

[0009] 3) performing secondary adsorption treatment on the primary adsorption effluent to obtain secondary adsorption effluent, wherein the adsorbent used in the secondary adsorption treatment is silica gel;

[0010] 4) performing membrane separation on the secondary adsorption effluent by using a nanofiltration membrane to obtain effluent.

[0011] Optionally, the filtering material is a glass fiber filter membrane, and the pore size of the glass fiber filter membrane is 0.45 μm.

[0012] Optionally, the temperature of the primary adsorption treatment is 15-60 °C, and the time is 5-30 min.

[0013] Optionally, the activated carbon accounts for 0.1-10% of the mass of the pretreated petrochemical wastewater.

[0014] Optionally, the temperature of the secondary adsorption treatment is 15-60 °C, and the time is 5-30 min.

[0015] Optionally, the silica gel accounts for 0.1-20% of the mass of the primary adsorption effluent.

[0016] Optionally, the nanofiltration membrane is a polyamide nanofiltration membrane, the pore size of the nanofiltration membrane is 0.2-1 nm, and the pressure of the membrane separation is 0.08-1.2 MPa.

[0017] Optionally, the method further comprises:

[0018] after the activated carbon and the silica gel saturated with adsorption are regenerated, the activated carbon and the silica gel are used for the primary adsorption treatment and the secondary adsorption treatment, respectively, wherein the regeneration temperature of the activated carbon is 300-600 °C, and the regeneration temperature of the silica gel is 80-220 °C.

[0019] Optionally, the method further comprises:

[0020] the concentrated water obtained by the membrane separation is used as petrochemical wastewater, and steps 1) to 4) are performed again; and

[0021] when the effluent obtained by the membrane separation does not meet the discharge requirements, the effluent is repeatedly subjected to steps 1) to 4).

[0022] The application also provides a system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupling membrane process, which is used for implementing the method and comprises a filtering unit, a first adsorption unit, a second adsorption unit, a nanofiltration unit, a water outlet tank, a water quality detection unit, an activated carbon regeneration unit and a silica gel regeneration unit,

[0023] The filtering unit is used for filtering petrochemical wastewater, and an input end of the filtering unit is connected with a water inlet end of the petrochemical wastewater.

[0024] An input end of the first adsorption unit is connected with an output end of the filtering unit, the first adsorption unit is provided with activated carbon, and the first adsorption unit is provided with a first water outlet end and a first adsorbent output end.

[0025] An input end of the second adsorption unit is connected with the first water outlet end of the first adsorption unit, the second adsorption unit is provided with silica gel, and the second adsorption unit is provided with a second water outlet end and a second adsorbent output end.

[0026] An input end of the nanofiltration unit is connected with the second water outlet end of the second adsorption unit, the nanofiltration unit is provided with a membrane assembly of nanofiltration membranes, and the nanofiltration unit is provided with a first output end and a second output end, the first output end is connected with the input end of the filtering unit, and the first output end is used for conveying the concentrated water intercepted to the filtering unit, and the second output end is used for outputting the filtered water.

[0027] An input end of the water outlet tank is connected with the second output end of the nanofiltration unit, and the water outlet tank is used for storing the filtered water, the water outlet tank is provided with a circulating water outlet end and a drainage end, and the circulating water outlet end is connected with the input end of the filtering unit.

[0028] The water quality detection unit is arranged in the water outlet tank and is used for detecting the water quality of the filtered water.

[0029] An input end of the activated carbon regeneration unit is connected with the first adsorbent output end of the first adsorption unit, and an output end of the activated carbon regeneration unit is connected with the input end of the first adsorption unit.

[0030] An input end of the silica gel regeneration unit is connected with the second adsorbent output end of the second adsorption unit, and an output end of the silica gel regeneration unit is connected with the input end of the second adsorption unit.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] The application provides a method and system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled membrane process. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The figure is a process flow diagram for deep treatment of petrochemical wastewater in the embodiment of the application.

[0034] Figure 2 The figure is a graph showing the change of TOC content in petrochemical wastewater of Example 1 with treatment time.

[0035] Figure 3 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Example 1.

[0036] Figure 4 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Example 2.

[0037] Figure 5 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Example 3.

[0038] Figure 6 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Example 4.

[0039] Figure 7 The figure is a graph showing the change of TOC content in petrochemical wastewater in the 5-cycle treatment process of the application.

[0040] Figure 8 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Comparative Example 1.

[0041] Figure 9 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Comparative Example 2.

[0042] Figure 10 The figure is a graph showing the change of TOC content in petrochemical wastewater in the treatment process of Comparative Example 3.

[0043] Figure 11The graph of the change of the TOC content of the petrochemical wastewater in the treatment process of the present application comparative example 4. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present application will now be described in detail, which should be considered to be illustrative of the application and not as limiting the application. It will be appreciated that the detailed description is intended to be merely illustrative of certain aspects of the application, and the application should not be limited to the specific embodiments described.

[0045] It should be understood that the terms used herein are merely descriptive, but are not intended to limit the application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range of values and any other stated value or stated range of values is also included within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0047] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples herein. The specification and examples given should be considered exemplary only.

[0048] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean "including but not limited to".

[0049] The raw materials used in the present application can be obtained commercially or prepared by the prior art.

[0050] As used herein, "room temperature" means 25±2°C, unless otherwise specified.

[0051] The present application provides a method for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled membrane process, comprising the following steps:

[0052] 1) filtering the petrochemical wastewater to obtain pretreated petrochemical wastewater;

[0053] 2) performing primary adsorption treatment on the pretreated petrochemical wastewater to obtain primary adsorption effluent, wherein the adsorbent used in the primary adsorption treatment is activated carbon;

[0054] 3) performing secondary adsorption treatment on the primary adsorption effluent to obtain secondary adsorption effluent, wherein the adsorbent used in the secondary adsorption treatment is silica gel;

[0055] 4) performing membrane separation on the secondary adsorption effluent by using a nanofiltration membrane to obtain effluent.

[0056] The pretreated petrochemical wastewater is obtained by filtering the petrochemical wastewater.

[0057] In the embodiments of the present application, the filtering material is a glass fiber filter membrane, and the membrane pore size is 0.45 μm. The petrochemical wastewater is filtered by using the filtering material to remove part of the solid substances and suspended particles in the wastewater.

[0058] The pretreated petrochemical wastewater is obtained by filtering the petrochemical wastewater.

[0059] In the embodiments of the present application, the activated carbon is a bituminous coal activated carbon from Shanxi Province, the pore size distribution range of the activated carbon is 0.5-150 nm, the average pore size is 2.12 nm, the large pore (> 50 nm) pore volume is 0.09 cm 3 / g, and the micropore volume is 0.62 cm / g. In the present application, the activated carbon containing large pores can better adsorb and remove the hydrophobic organic substances in the petrochemical wastewater.

[0060] In some embodiments of the present application, the temperature of the primary adsorption treatment is 15-60 °C, preferably 20-50 °C, and further preferably 30-40 °C, and the time is 5-30 min, preferably 10-25 min, and further preferably 15-20 min.

[0061] In the present application, after the primary adsorption treatment is completed, solid-liquid separation is performed. The present application does not limit the mode of solid-liquid separation, and in the embodiments of the present application, the primary adsorption effluent and the activated carbon are separated by filtration.

[0062] In some embodiments of the present application, the activated carbon accounts for 0.1-10% of the mass of the pretreated petrochemical wastewater, preferably 0.8-8%, and further preferably 1.2-2%.

[0063] The pretreated petrochemical wastewater is obtained by filtering the petrochemical wastewater.

[0064] In the embodiments of the present application, the silica gel is an industrial-grade silica gel, and the specific CAS number is 112926-00-8. The pore size distribution range of the silica gel is 0.5-50 nm, the average pore size is 2.51 nm, the mesopore (2-50 nm) pore volume is 0.37 cm 3 In the present application, the silica gel can adsorb and remove the hydrophilic organic matter in the petrochemical wastewater.

[0065] In some embodiments of the present application, the temperature of the secondary adsorption treatment is 15-60 DEG C, preferably 20-50 DEG C, and further preferably 30-40 DEG C. The time is 5-30 min, preferably 10-25 min, and further preferably 15-20 min.

[0066] In the present application, after the secondary adsorption treatment is completed, solid-liquid separation is performed. The present application does not limit the solid-liquid separation method, and in the embodiments of the present application, the secondary adsorption effluent and the silica gel are separated by filtration.

[0067] In some embodiments of the present application, the silica gel accounts for 0.1-20% of the mass of the primary adsorption effluent, preferably 1.2-10%, and further preferably 2-5%.

[0068] In some embodiments of the present application, the activated carbon and the silica gel after adsorption saturation are regenerated and then used for the primary adsorption treatment and the secondary adsorption treatment, respectively. The regeneration temperature of the activated carbon is 300-600 DEG C, preferably 400-500 DEG C, and the time is 1 h. The regeneration temperature of the silica gel is 80-220 DEG C, preferably 100-150 DEG C, and further preferably 120-130 DEG C, and the time is 4 h.

[0069] After the secondary adsorption effluent is obtained, the secondary adsorption effluent is subjected to membrane separation by a nanofiltration membrane to obtain the effluent.

[0070] The present application does not have special limitations on the type of nanofiltration membrane, and the nanofiltration membrane can be used to deeply remove the residual macromolecular pollutants in the petrochemical wastewater. In some embodiments of the present application, the nanofiltration membrane is a polyamide nanofiltration membrane, and the pore size of the nanofiltration membrane is 0.2-1 nm, preferably 0.2-0.6 nm, and further preferably 0.2-0.45 nm.

[0071] In some embodiments of the present application, the pressure of the membrane separation is 0.08-1.2 MPa, preferably 0.2-1 MPa, and further preferably 0.4-0.8 MPa.

[0072] In some embodiments of the present application, the concentrated water obtained by the membrane separation is used as the petrochemical wastewater, and steps 1)-4) are performed again.

[0073] When the membrane separation effluent water does not meet the discharge requirements, repeat steps 1) to 4).

[0074] The application also provides a system for deep treatment of petrochemical wastewater based on hierarchical adsorption coupled membrane process, for implementing the above method, comprising a filtration unit, a first adsorption unit, a second adsorption unit, a nanofiltration unit, a water tank, a water quality detection unit, an activated carbon regeneration unit and a silica gel regeneration unit,

[0075] The filtration unit is used for filtering petrochemical wastewater, and an input end thereof is connected with a petrochemical wastewater inlet end.

[0076] An input end of the first adsorption unit is connected with an output end of the filtration unit, the first adsorption unit is provided with activated carbon, and the first adsorption unit is provided with a first effluent end and a first adsorbent output end.

[0077] An input end of the second adsorption unit is connected with the first effluent end of the first adsorption unit, the second adsorption unit is provided with silica gel, and the second adsorption unit is provided with a second effluent end and a second adsorbent output end.

[0078] An input end of the nanofiltration unit is connected with the second effluent end of the second adsorption unit, the nanofiltration unit is provided with a membrane assembly of nanofiltration membranes, and the nanofiltration unit is provided with a first output end and a second output end, the first output end is connected with the input end of the filtration unit, and the first output end is used for conveying the concentrated water intercepted to the filtration unit, and the second output end is used for outputting the nanofiltration water.

[0079] An input end of the effluent tank is connected with the second output end of the nanofiltration unit, and the effluent tank is used for storing the nanofiltration water, the effluent tank is provided with a circulating effluent end and a drainage end, and the circulating effluent end is connected with the input end of the filtration unit.

[0080] The water quality detection unit is arranged in the effluent tank and is used for detecting the water quality of the water.

[0081] An input end of the activated carbon regeneration unit is connected with the first adsorbent output end of the first adsorption unit, and an output end of the activated carbon regeneration unit is connected with the input end of the first adsorption unit.

[0082] An input end of the silica gel regeneration unit is connected with the second adsorbent output end of the second adsorption unit, and an output end of the silica gel regeneration unit is connected with the input end of the second adsorption unit.

[0083] In the embodiment of the application, the water quality detector is used for detecting the water quality, the water quality detection is detecting the TOC of the sewage by the water quality detector, the effluent water is discharged after passing the detection, and the first adsorption treatment is performed again and the subsequent treatment method is repeated when the detection fails.

[0084] The technical solutions provided by the present application are described in detail below in combination with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0085] The following examples all use Figure 1 The system shown in the figure is used for deep treatment of petrochemical wastewater, specifically: the system comprises a filtering unit, a first-stage adsorption unit, a second-stage adsorption unit, a nanofiltration unit, a water outlet tank, a water quality detection unit, an activated carbon regeneration unit, and a silica gel regeneration unit,

[0086] The filtering unit is used for filtering petrochemical wastewater, and its input end is connected with the water inlet end of the petrochemical wastewater.

[0087] The first-stage adsorption unit is connected with the output end of the filtering unit, and the first-stage adsorption unit is provided with a first-stage water outlet end and a first-stage adsorbent output end.

[0088] The second-stage adsorption unit is connected with the first-stage water outlet end of the first-stage adsorption unit, and the second-stage adsorption unit is provided with a second-stage water outlet end and a second-stage adsorbent output end.

[0089] The nanofiltration unit is connected with the second-stage water outlet end of the second-stage adsorption unit, and the nanofiltration unit is provided with a first output end and a second output end, the first output end is connected with the input end of the filtering unit, and the first output end is used for conveying the concentrated water intercepted to the filtering unit, and the second output end is used for outputting the filtered water.

[0090] The input end of the water outlet tank is connected with the second output end of the nanofiltration unit, and the water outlet tank is used for storing the filtered water, and the water outlet tank is provided with a circulating water outlet end and a drainage end, and the circulating water outlet end is connected with the input end of the filtering unit.

[0091] The water quality detection unit is arranged in the water outlet tank and is used for detecting the water quality of the filtered water.

[0092] The input end of the activated carbon regeneration unit is connected with the first-stage adsorbent output end of the first-stage adsorption unit, and the activated carbon regeneration unit is used for conveying the saturated activated carbon in the first-stage adsorption unit to the activated carbon regeneration unit, and the output end of the activated carbon regeneration unit is connected with the input end of the first-stage adsorption unit, and the activated carbon regeneration unit is used for conveying the regenerated activated carbon to the first-stage adsorption unit for recycling.

[0093] The input end of the silica gel regeneration unit is connected with the second-stage adsorbent output end of the second-stage adsorption unit, and the silica gel regeneration unit is used for conveying the saturated silica gel in the second-stage adsorption unit to the silica gel regeneration unit, and the output end of the silica gel regeneration unit is connected with the input end of the second-stage adsorption unit, and the silica gel regeneration unit is used for conveying the regenerated silica gel to the second-stage adsorption unit for recycling.

[0094] Example 1

[0095] according to Figure 1 The process flow shown demonstrates the deep treatment of petrochemical wastewater. Under conditions of 25°C and pH 7, the TOC content in the petrochemical wastewater is 175 ppm.

[0096] 1) Petrochemical wastewater was filtered through a glass fiber membrane with a pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content in the effluent of the pretreated petrochemical wastewater was 150 ppm.

[0097] 2) The pretreated petrochemical wastewater is transported to a facility equipped with an average pore size of 2.12 nm and macropores (>50 nm) with a pore volume of 0.09 cm³. 3 In the primary adsorption unit of / g bituminous activated carbon, the bituminous activated carbon accounts for 1.2% of the mass of the pretreated petrochemical wastewater. The adsorption is carried out at 25℃ for 0.5h to complete the primary adsorption treatment. Then, the bituminous activated carbon after primary adsorption treatment and the primary adsorption effluent are filtered and separated to obtain the primary adsorption effluent and the adsorption saturated bituminous activated carbon.

[0098] 3) The effluent from the first-stage adsorption is transported to a device with an average pore size of 2.51 nm and a mesopore volume of 0.37 cm³. 3 In the secondary adsorption unit of silica gel with CAS model 112926-00-8, silica gel accounts for 2% of the mass of the effluent from the primary adsorption. Adsorption is carried out at 25℃ for 0.5h to complete the secondary adsorption treatment. Then, the silica gel after secondary adsorption treatment and the effluent from the secondary adsorption are filtered and separated to obtain the effluent from the secondary adsorption and the silica gel saturated by adsorption.

[0099] 4) The secondary adsorption effluent is passed through a polyamide nanofiltration membrane with a pore size of 0.45 nm and separated under a pressure of 0.8 MPa. After membrane separation, nanofiltration effluent and concentrate are obtained. The nanofiltration effluent is sent to the effluent tank and the concentrate is sent to the pretreatment tank.

[0100] The TOC content of the water in the outlet tank was measured to be 18 ppm using a water quality analyzer, which complies with the "Emission Standard of Pollutants for Petrochemical Industry" (GB 31571-2015, including the 2024 amendment). The water was then discharged from the outlet by a drainage pump.

[0101] Figure 2 The graph shows the change in TOC content in petrochemical wastewater as a function of treatment time in Example 1. It can be seen that the petrochemical wastewater can reach primary adsorption equilibrium after 10 to 30 minutes, secondary adsorption equilibrium after 30 minutes, and nanofiltration treatment efficiency remains stable after 4 hours.

[0102] Figure 3is a graph of the content change of TOC in the petrochemical wastewater treatment process of Example 1. As can be seen, after the petrochemical wastewater is pretreated, primary adsorbed, secondary adsorbed and nanofiltration treated, the water permeation flux of the polyamide nanofiltration membrane is 13.48 L·m -2 ·h -1 ·bar -1 , the TOC content of the petrochemical wastewater is reduced from the initial 175 ppm to 18 ppm, the pollutants in the petrochemical wastewater can be removed, and the petrochemical wastewater can be deeply treated.

[0103] Example 2

[0104] Under the condition of 25℃ and pH 3, the TOC content in the petrochemical wastewater is 173 ppm:

[0105] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 141 ppm.

[0106] 2) The pretreated petrochemical wastewater is transported to a primary adsorption unit filled with bituminous coal activated carbon with an average pore size of 2.12 nm, a large pore (> 50 nm) pore volume of 0.09 cm 3 / g, and the bituminous coal activated carbon accounts for 1.2% of the mass of the pretreated petrochemical wastewater. The primary adsorption treatment is completed at 25℃ for 0.5h, then the bituminous coal activated carbon after primary adsorption treatment and the primary adsorption effluent are filtered and separated to obtain the primary adsorption effluent.

[0107] 3) The primary adsorption effluent is transported to a secondary adsorption unit filled with silica gel with an average pore size of 2.51 nm, a mesopore (2-50 nm) pore volume of 0.37 cm 3 / g, and the CAS model number is 112926-00-8. The silica gel accounts for 2% of the mass of the primary adsorption effluent. After the silica gel is saturated, the secondary adsorption treatment is completed at 25℃ for 0.5h, then the silica gel after secondary adsorption treatment and the secondary adsorption effluent are filtered and separated to obtain the secondary adsorption effluent and the saturated silica gel.

[0108] 4) The secondary adsorption effluent is separated by membrane separation through a polyamide nanofiltration membrane with a pore size of 0.2 nm under a pressure of 0.8 MPa, and the nanofiltration effluent and the concentrated water are obtained after membrane separation. The nanofiltration effluent is transported to the effluent tank, and the concentrated water is transported to the pretreatment tank.

[0109] The TOC content of the effluent in the effluent tank is detected by a water quality detector to be 7 ppm, which meets the “Petroleum Chemical Industry Pollutant Discharge Standard” (GB 31571-2015, including the 2024 amendment), and is discharged from the effluent end by a drainage pump.

[0110] Figure 4is a graph of the content change of TOC in the petrochemical wastewater treatment process of Example 2. It can be seen that, after the petrochemical wastewater is pretreated, primary adsorption, secondary adsorption and nanofiltration treatment, the water permeation flux of the polyamide nanofiltration membrane is 2.76 L·m -2 ·h -1 ·bar -1 , the TOC content of the petrochemical wastewater is reduced from 173 ppm to 7 ppm, the pollutants in the petrochemical wastewater can be removed, and the petrochemical wastewater can be deeply treated.

[0111] Example 3

[0112] The TOC content of the petrochemical wastewater is 178 ppm at 15℃ and pH 3;

[0113] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a membrane pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 150 ppm.

[0114] 2) The pretreated petrochemical wastewater is transported to a primary adsorption unit containing bituminous coal activated carbon with an average pore size of 2.12 nm, a large pore (> 50 nm) pore volume of 0.09 cm 3 / g, and the bituminous coal activated carbon accounts for 1.2% of the mass of the pretreated petrochemical wastewater. The primary adsorption treatment is completed at 15℃ for 0.5 h, and then the activated carbon after primary adsorption treatment and the primary adsorption effluent are filtered and separated to obtain the primary adsorption effluent.

[0115] 3) The primary adsorption effluent is transported to a secondary adsorption unit containing silica gel with an average pore size of 2.51 nm, a mesopore (2-50 nm) pore volume of 0.37 cm 3 / g, and the CAS model number is 112926-00-8. The silica gel accounts for 2% of the mass of the primary adsorption effluent. The secondary adsorption treatment is completed at 15℃ for 0.5 h, and then the silica gel after secondary adsorption treatment and the secondary adsorption effluent are filtered and separated to obtain the secondary adsorption effluent.

[0116] 4) The secondary adsorption effluent is separated by membrane separation through a polyamide nanofiltration membrane with a pore size of 0.25 nm under a pressure of 0.8 MPa. The nanofiltration effluent and the concentrated water are obtained after membrane separation. The nanofiltration effluent is transported to the effluent tank, and the concentrated water is transported to the pretreatment tank.

[0117] The TOC content of the effluent in the effluent tank is detected by a water quality detector to be 12 ppm, which meets the “Petroleum Chemical Industry Pollutant Discharge Standard” (GB 31571-2015, including the 2024 amendment), and is discharged from the effluent end by a drainage pump.

[0118] Figure 5is a graph of the content change of TOC in the petrochemical wastewater treatment process of Example 3. It can be seen that, after the petrochemical wastewater is pretreated, primary adsorbed, secondary adsorbed and nanofiltrated, the water permeation flux of the polyamide nanofiltration membrane is 3.54 L·m -2 ·h -1 ·bar -1 , the TOC content of the petrochemical wastewater is reduced from the initial 178 ppm to 12 ppm, the pollutants in the petrochemical wastewater can be removed, and the petrochemical wastewater can be deeply treated.

[0119] Example 4

[0120] The TOC content of the petrochemical wastewater is 105 ppm at 25℃ and pH 7.

[0121] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 101 ppm.

[0122] 2) The pretreated petrochemical wastewater is transported to a primary adsorption unit containing a mixture of bituminous coal activated carbon with an average pore size of 2.12 nm, a large pore (> 50 nm) pore volume of 0.09 cm 3 / g, and the bituminous coal activated carbon accounts for 0.8% of the mass of the pretreated petrochemical wastewater. The primary adsorption treatment is completed at 25℃ for 0.5 h, and then the bituminous coal activated carbon after primary adsorption treatment and the primary adsorption effluent are filtered and separated to obtain the primary adsorption effluent.

[0123] 3) The primary adsorption effluent is transported to a secondary adsorption unit containing silica gel with an average pore size of 2.51 nm, a mesopore (2-50 nm) pore volume of 0.37 cm 3 / g, and the CAS model number is 112926-00-8. The silica gel accounts for 1.2% of the mass of the primary adsorption effluent. The secondary adsorption treatment is completed at 25℃ for 0.5 h, and then the silica gel after secondary adsorption treatment and the secondary adsorption effluent are filtered and separated to obtain the secondary adsorption effluent.

[0124] 4) The secondary adsorption effluent is separated by membrane separation through a polyamide nanofiltration membrane with a pore size of 0.22 nm under a pressure of 0.8 MPa. The nanofiltration effluent and the concentrated water are obtained after membrane separation. The nanofiltration effluent is transported to the effluent tank, and the concentrated water is transported to the pretreatment tank.

[0125] The TOC content of the effluent in the effluent tank is detected by a water quality detector to be 10 ppm, which meets the “Petroleum Chemical Industry Pollutant Discharge Standard” (GB 31571-2015, including the 2024 amendment), and is discharged from the effluent end by a drainage pump.

[0126] Figure 6This is a graph showing the change in TOC content during the petrochemical wastewater treatment process in Example 4. It can be seen that after pretreatment, primary adsorption, secondary adsorption, and nanofiltration, the water permeability flux of the polyamide nanofiltration membrane is 3.02 L·m³. -2 ·h -1 ·bar -1 The TOC content of petrochemical wastewater was reduced from an initial 105 ppm to 10 ppm, which can remove pollutants from petrochemical wastewater and achieve deep treatment of petrochemical wastewater.

[0127] Example 5

[0128] The saturated bituminous activated carbon from Example 1 is transported to the activated carbon regeneration unit and regenerated at 600°C for 1 hour to obtain regenerated bituminous activated carbon. The regenerated bituminous activated carbon is then transported to the primary adsorption unit.

[0129] The silica gel saturated with adsorption in Example 1 was transported to the silica gel regeneration unit and regenerated at 120°C for 4 hours to obtain regenerated silica gel, which was then transported to the secondary adsorption unit.

[0130] The nanofiltration membrane used in Example 1 was reversed and backwashed with effluent at 25°C for 1 hour to obtain a regenerated nanofiltration membrane, which was then placed into the nanofiltration unit.

[0131] Example 6

[0132] The only difference from Example 1 is that the primary adsorption unit is filled with the regenerated bituminous activated carbon of Example 5; the secondary adsorption unit is filled with the regenerated silica gel of Example 5; and the nanofiltration unit is filled with the regenerated nanofiltration membrane of Example 5.

[0133] After the petrochemical wastewater treatment in Example 6 is completed, the saturated regenerated bituminous activated carbon, regenerated silica gel, and regenerated nanofiltration membrane are regenerated. After the regeneration treatment is completed, they are returned to the primary adsorption unit, secondary adsorption unit, and nanofiltration unit, respectively, and the petrochemical wastewater is treated according to the steps in Example 1. The process is repeated 3 times based on Example 6.

[0134] Figure 7 This is a graph showing the change in TOC content during the five cycles of petrochemical wastewater treatment. It can be seen that after pretreatment with material regeneration, primary adsorption, secondary adsorption, and nanofiltration, the TOC content of the petrochemical wastewater can still be reduced from the initial 175 ppm to below 20 ppm. This effectively removes pollutants from the petrochemical wastewater, achieving deep treatment of the wastewater and complying with the "Emission Standard of Pollutants for Petrochemical Industry" (GB 31571-2015, including the 2024 amendment).

[0135] The TOC content of the primary adsorption effluent obtained after the bituminous coal activated carbon is adsorbed and saturated and the TOC content of the primary adsorption effluent obtained after the regenerated bituminous coal activated carbon is adsorbed and saturated are tested, the initial adsorption capacity of the bituminous coal activated carbon is calculated by the calculation formula of the adsorption capacity, is 5.6 mg / g, after 5 times of cyclic regeneration and use, the adsorption capacity is still stable at 5.3 mg / g, which shows that the bituminous coal activated carbon in the scheme has the reproducibility and can be cyclically used.

[0136] The TOC content of the secondary adsorption effluent obtained after the silica gel is adsorbed and saturated and the TOC content of the secondary adsorption effluent obtained after the regenerated silica gel is adsorbed and saturated are tested, the initial adsorption capacity of the silica gel is calculated by the calculation formula of the adsorption capacity, is 2.6 mg / g, after 5 times of cyclic regeneration and use, the adsorption capacity is still stable at 2.4 mg / g, which shows that the silica gel in the scheme has the reproducibility and can be cyclically used.

[0137] The TOC content of the nanofiltration effluent obtained after the nanofiltration membrane is separated and the TOC content of the nanofiltration effluent obtained after the regenerated nanofiltration membrane is separated are tested, the initial separation efficiency of the nanofiltration membrane is calculated, is 39.3%, after 5 times of cyclic regeneration and use, the separation efficiency is still stable at 37.1%, which shows that the nanofiltration membrane has the reproducibility and can be cyclically used.

[0138] Comparative Example 1

[0139] The TOC content of the petrochemical wastewater is 175 ppm under the condition that the temperature is 15 ℃ and the pH is 3;

[0140] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a membrane pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 148 ppm.

[0141] 2) The pretreated petrochemical wastewater is transported to a primary adsorption unit provided with bituminous coal activated carbon with an average pore size of 2.12 nm, a large pore (> 50 nm) pore volume of 0.09 cm 3 / g, the bituminous coal activated carbon accounts for 0.8% of the mass of the pretreated petrochemical wastewater, and the primary adsorption treatment is completed under the condition that the adsorption is carried out at 25 ℃ for 0.5 h, then the bituminous coal activated carbon after the primary adsorption treatment and the primary adsorption effluent are filtered and separated to obtain the primary adsorption effluent.

[0142] 3) The primary adsorption effluent is transported to a secondary adsorption unit provided with silica gel with an average pore size of 2.51 nm, a mesopore (2-50 nm) pore volume of 0.37 cm 3 / g, the silica gel accounts for 1.2% of the mass of the primary adsorption effluent, and the secondary adsorption treatment is completed at 25°C for 0.5h, then the silica gel after the secondary adsorption treatment and the secondary adsorption effluent are filtered and separated to obtain the secondary adsorption effluent. The water quality detector is used to detect the TOC content of the secondary adsorption effluent, and the TOC content is 29ppm.

[0143] Figure 8 Figure 1 is a graph of the change in the TOC content in the petrochemical wastewater treatment process of Comparative Example 1, and it can be seen that the TOC content of the petrochemical wastewater is reduced from the initial 175ppm to 29ppm after the petrochemical wastewater is pretreated, subjected to primary adsorption and secondary adsorption, which does not meet the “Discharge Standard of Pollutants in Petroleum Chemical Industry” (GB 31571-2015, including the 2024 amendment).

[0144] Comparative Example 2

[0145] The TOC content of the petrochemical wastewater is 175ppm at 15°C and pH 3.

[0146] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a membrane pore size of 0.45μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 148ppm.

[0147] 2) The pretreated petrochemical wastewater is transported to an adsorption unit containing bituminous coal activated carbon with an average pore size of 2.12nm, a large pore (>50nm) pore volume of 0.09cm 3 / g, the bituminous coal activated carbon accounts for 0.8% of the mass of the pretreated petrochemical wastewater, and the adsorption treatment is completed at 25°C for 0.5h, then the bituminous coal activated carbon after the adsorption treatment and the adsorption effluent are filtered and separated to obtain the primary adsorption effluent.

[0148] 3) The adsorption effluent is subjected to membrane separation through a polyamide nanofiltration membrane with a pore size of 0.2nm at a pressure of 0.8MPa, and the nanofiltration effluent and the concentrated water are obtained after the membrane separation, and the nanofiltration effluent is transported to the effluent tank, and the concentrated water is transported to the pretreatment tank.

[0149] The water quality detector is used to detect the TOC content of the nanofiltration effluent, and the TOC content is 25ppm.

[0150] Figure 9 Figure 2 is a graph of the change in the TOC content in the petrochemical wastewater treatment process of Comparative Example 2, and it can be seen that the TOC content of the petrochemical wastewater is reduced from the initial 175ppm to 25ppm after the petrochemical wastewater is pretreated, subjected to primary adsorption and nanofiltration treatment, and the water permeation flux of the polyamide nanofiltration membrane is 1.54L·m -2 ·h -1 ·bar -1, the TOC content of the petrochemical wastewater is reduced from the initial 175 ppm to 25 ppm, which does not meet the "Pollutant Discharge Standard for Petroleum Chemical Industry" (GB31571-2015, including the 2024 amendment).

[0151] Comparative Example 3

[0152] The TOC content of the petrochemical wastewater is 175 ppm at 15°C and pH 3;

[0153] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a membrane pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 148 ppm.

[0154] 2) The pretreated petrochemical wastewater is transported to an adsorption unit containing silica gel with an average pore size of 2.51 nm and a mesopore (2-50 nm) pore volume of 0.37 cm 3 / g, CAS No. 112926-00-8, the silica gel accounts for 1.2% of the mass of the pretreated petrochemical wastewater, and the adsorption treatment is completed at 25°C for 0.5 h, then the adsorbed silica gel and the adsorbed effluent are separated by filtration to obtain the adsorbed effluent.

[0155] 3) The adsorbed effluent is separated by membrane separation through a polyamide nanofiltration membrane with a pore size of 0.2 nm at a pressure of 0.8 MPa, and the nanofiltration effluent and the concentrated water are obtained after membrane separation, the nanofiltration effluent is transported to the effluent tank, and the concentrated water is transported to the pretreatment tank.

[0156] The TOC content of the nanofiltration effluent is detected by a water quality detector and is 21 ppm.

[0157] Figure 10 is the TOC content change graph during the treatment of the petrochemical wastewater in Comparative Example 3, it can be seen that after the pretreatment, secondary adsorption and nanofiltration treatment of the petrochemical wastewater, the water permeation flux of the polyamide nanofiltration membrane is 2.58 L·m -2 ·h -1 ·bar -1 The TOC content of the petrochemical wastewater is reduced from the initial 175 ppm to 21 ppm, which does not meet the "Pollutant Discharge Standard for Petroleum Chemical Industry" (GB31571-2015, including the 2024 amendment).

[0158] Comparative Example 4

[0159] The TOC content of the petrochemical wastewater is 175 ppm at 15°C and pH 3;

[0160] 1) The petrochemical wastewater is filtered through a glass fiber filter membrane with a membrane pore size of 0.45 μm to obtain pretreated petrochemical wastewater. The TOC content of the pretreated petrochemical wastewater effluent is 148 ppm.

[0161] 2) The pretreated petrochemical wastewater is subjected to membrane separation through a polyamide nanofiltration membrane with a pore size of 0.2 nm at a pressure of 0.8 MPa, and after the membrane separation, nanofiltration effluent and concentrated water are obtained, the nanofiltration effluent is transported to an effluent tank, and a water quality detector is used to detect the TOC content of the nanofiltration effluent, which is 42 ppm.

[0162] Figure 11 is a graph showing the change in the TOC content in the process of treating the petrochemical wastewater of Comparative Example 4, and it can be seen that after the pretreatment and nanofiltration treatment of the petrochemical wastewater, the water permeation flux of the polyamide nanofiltration membrane is 0.98 L·m -2 ·h -1 ·bar -1 , and the TOC content of the petrochemical wastewater is reduced from the initial 175 ppm to 42 ppm, which does not meet the Discharge Standard of Pollutants in Petroleum Chemical Industry (GB 31571-2015, including the 2024 amendment).

[0163] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A method for deep treatment of petrochemical wastewater based on a staged adsorption-coupled membrane process, characterized in that, Includes the following steps: 1) The petrochemical wastewater is filtered to obtain pretreated petrochemical wastewater; 2) The pretreated petrochemical wastewater is subjected to primary adsorption treatment to obtain primary adsorbed effluent, wherein the adsorbent used in the primary adsorption treatment is activated carbon. 3) The primary adsorbed water is subjected to secondary adsorption treatment to obtain secondary adsorbed water, wherein the adsorbent used in the secondary adsorption treatment is silica gel; 4) The effluent from the secondary adsorption process is passed through a nanofiltration membrane for membrane separation to obtain the effluent; The activated carbon is bituminous coal activated carbon, with a pore size distribution range of 0.5–150 nm, an average pore size of 2.12 nm, and a macropore volume >50 nm of 0.09 cm³. 3 / g; The silicone is industrial-grade silicone, specifically CAS number 112926-00-8. The silicone has a pore size distribution range of 0.5–50 nm, an average pore size of 2.51 nm, and a mesopore volume of 0.37 cm³ for pores ranging from 2 to 50 nm. 3 / g.

2. The method according to claim 1, characterized in that, The filtration material is a glass fiber filter membrane with a pore size of 0.45 μm.

3. The method according to claim 1, characterized in that, The temperature of the primary adsorption treatment is 15–60°C, and the time is 5–30 min.

4. The method according to claim 3, characterized in that, The activated carbon accounts for 0.1% to 10% of the mass of the pretreated petrochemical wastewater.

5. The method according to claim 1, characterized in that, The secondary adsorption treatment is carried out at a temperature of 15–60°C for a time of 5–30 min.

6. The method according to claim 5, characterized in that, The silica gel comprises 0.1% to 20% of the mass of the effluent from the first-stage adsorption.

7. The method according to claim 1, characterized in that, The nanofiltration membrane is a polyamide nanofiltration membrane with a pore size of 0.2–1 nm; the membrane separation pressure is 0.08–1.2 MPa.

8. The method according to any one of claims 1 and 3 to 6, characterized in that, The method further includes: After the activated carbon and silica gel are saturated with adsorption, they are regenerated and used for primary adsorption treatment and secondary adsorption treatment, respectively. The regeneration temperature of the activated carbon is 300-600℃ and the regeneration temperature of the silica gel is 80-220℃.

9. The method according to claim 1, characterized in that, The method further includes: The concentrated water obtained from membrane separation is used as petrochemical wastewater, and steps 1) to 4) are repeated; and If the water obtained from the membrane separation does not meet the discharge requirements, steps 1) to 4) are repeated.

10. A system for deep treatment of petrochemical wastewater based on a staged adsorption-coupled membrane process, used to implement the method according to any one of claims 1 to 9, characterized in that, It includes a filtration unit, a primary adsorption unit, a secondary adsorption unit, a nanofiltration unit, an outlet tank, a water quality testing unit, an activated carbon regeneration unit, and a silica gel regeneration unit. The filtration unit is used to filter petrochemical wastewater, and its input end is connected to the petrochemical wastewater inlet end. The input end of the primary adsorption unit is connected to the output end of the filtration unit. The primary adsorption unit is filled with activated carbon and is provided with a primary water outlet and a primary adsorbent output. The input end of the secondary adsorption unit is connected to the primary water outlet end of the primary adsorption unit. The secondary adsorption unit is filled with silica gel and is provided with a secondary water outlet end and a secondary adsorbent output end. The input end of the nanofiltration unit is connected to the secondary outlet end of the secondary adsorption unit. The nanofiltration unit contains a membrane module with a nanofiltration membrane. The nanofiltration unit is provided with a first output end and a second output end. The first output end is connected to the input end of the filtration unit and is used to transport the intercepted concentrated water to the filtration unit. The second output end is used to output the purified water after nanofiltration. The input end of the water outlet tank is connected to the second output end of the nanofiltration unit and is used to store the purified water after nanofiltration. The water outlet tank is provided with a circulating water outlet and a drain end, and the circulating water outlet is connected to the input end of the filtration unit. The water quality detection unit is installed in the water outlet tank and is used to detect the water quality of the purified water; The input end of the activated carbon regeneration unit is connected to the output end of the primary adsorbent of the primary adsorption unit, and the output end of the activated carbon regeneration unit is connected to the input end of the primary adsorption unit. The input end of the silica gel regeneration unit is connected to the output end of the secondary adsorbent of the secondary adsorption unit, and the output end of the silica gel regeneration unit is connected to the input end of the secondary adsorption unit.

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