A method for advanced treatment of high-concentration refractory organic wastewater

Abstract

The present invention relates to a method for advanced treatment of high-concentration refractory organic wastewater. The method includes injecting the to-be-treated high-concentration refractory organic wastewater into a coagulation sedimentation tank, adding polyferric chloride and PAM, and then adjusting the pH to 9-10 with an alkali for flocculation sedimentation to remove fine suspended solids and calcium, magnesium and iron ions in the wastewater; mixing the supernatant with ozone water and discharging it into a contact oxidation tank, using a heterogeneous ozone catalyst in the contact oxidation tank for catalytic oxidation to remove COD and ammonia nitrogen pollutants, so that the sewage meets the discharge standard and a part of the qualified sewage is discharged; the remaining qualified sewage sequentially enters two-stage DTRO treatment units, the concentrated liquid generated by each stage of DTRO is discharged into the coagulation sedimentation tank, and the permeate passing through the two-stage DTRO treatment units enters an electrolytic cell; after the permeate enters the electrolytic cell, ozone is electrolyzed to form ozone water with a concentration of 18%-20% and discharged into the contact oxidation tank; the electrolytic cell consists of an anode chamber, a cathode chamber and a PEM membrane, and the anode electrode in the anode chamber is a nano-coated electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of treatment of refractory organic wastewater, and particularly to a method for advanced treatment of high-concentration refractory organic wastewater. Background Art

[0002] The problem of treating high-concentration organic wastewater is a recognized difficult problem in current world sewage treatment. The so-called high-concentration wastewater refers to some wastewater with high concentration, high salt content, and high recalcitrance. The water quality components are complex, the organic matter content is high, and the COD is generally above 10000 mg / L, and even up to tens of thousands to hundreds of thousands of milligrams per liter. And it generally contains toxic and harmful substances, has a very high salt content, and has strong acidity or alkalinity, and cannot be directly subjected to biochemical treatment.

[0003] This type of industrial wastewater is generally produced from industries such as the coking industry, pharmaceuticals, pesticides, petrochemical / oil industries, textile / dyeing industries, chemical industries, and paint industries. Such high-concentration organic wastewater causes great pollution to the environment and has a long-lasting impact. If not properly treated, it will not only damage the ecological environment but also harm humans themselves.

[0004] Therefore, there is an urgent need to provide a method for advanced treatment of high-concentration refractory organic wastewater to achieve the degradation of sewage. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for advanced treatment of high-concentration refractory organic wastewater.

[0006] To solve the above problems, the technical solution adopted by the present invention is:

[0007] A method for advanced treatment of high-concentration refractory organic wastewater, the method includes a startup stage and a circulation stage, and the startup stage is used to generate ozone water for the startup stage;

[0008] The circulation stage includes:

[0009] Step 1: Inject the high-concentration refractory organic wastewater to be treated into a coagulation sedimentation tank. After sequentially adding polyferric chloride and PAM in the coagulation sedimentation tank, adjust the pH to 9-10 with alkali for flocculation sedimentation to remove fine suspended solids and calcium, magnesium, and iron ions in the wastewater, and the supernatant enters the next process;

[0010] Step 2: Mix the supernatant with ozone water and then discharge it into a contact oxidation tank. Use the heterogeneous ozone catalyst in the contact oxidation tank for catalytic oxidation to remove COD and ammonia nitrogen pollutants, so that the sewage meets the discharge standard. 90%-95% of the up-to-standard sewage is discharged, and the remaining up-to-standard sewage enters the next process;

[0011] Step 3: The remaining qualified sewage enters the two-stage DTRO treatment unit in sequence. The concentrated liquid generated by each stage of DTRO is discharged into the coagulation sedimentation tank, and the permeate passing through the two-stage DTRO treatment unit enters the electrolytic cell.

[0012] Step 4: After the permeate enters the electrolytic cell, ozone is electrolyzed to form ozone water with a concentration of 18% - 20% and is discharged into the contact oxidation tank. The electrolytic cell consists of an anode chamber, a cathode chamber, and a PEM membrane, and the anode electrode in the anode chamber is a nano-coated electrode.

[0013] As an embodiment of the invention, in Step 1, the alkali used is sodium hydroxide; the dosage of polyferric chloride is 1000 - 2000 mg / L, the dosage of PAM is 1 - 2 mg / L, and sodium hydroxide is added to adjust the pH to 9 - 10.

[0014] As an embodiment of the invention, in Step 2, the heterogeneous ozone catalyst is composed of an aluminum-based ozone catalyst, a silicon-aluminum ozone catalyst, and a silicon-aluminum-titanium ozone catalyst mixed in a mass ratio of 1:3.5:0.5.

[0015] As an embodiment of the invention, in Step 2, the ozone amount value Q 臭氧 in the ozone water is obtained by using the following formula:

[0016] Q 臭氧 = [(inlet COD value - outlet COD value) × 3 + (inlet ammonia nitrogen value - outlet ammonia nitrogen value) × 5.33] × (1.24 - 1.45).

[0017] As an embodiment of the invention, in Step 3, after a reducing agent is added to the qualified sewage, it enters the two-stage DTRO treatment unit in sequence. The reducing agent is sodium bisulfite.

[0018] As an embodiment of the invention, the mass fraction of the reducing agent is 1.5%.

[0019] As an embodiment of the invention, the first-stage DTRO treatment unit consists of a sand filter, a high-pressure pump, a first-stage DTRO membrane column, an on-line booster pump, and supporting pipelines and valves; the permeate of the first-stage DTRO enters the second-stage DTRO system, and the second-stage DTRO treatment unit consists of a high-pressure pump, a second-stage DTRO membrane column, and supporting pipelines and valves;

[0020] The first-stage DTRO membrane column and the second-stage DTRO membrane column adopt the same DTRO membrane column structure, which both include: RO membrane sheets, flow guide discs, O-ring rubber gaskets, central tie rods, and membrane shells, and the RO membrane sheets are seawater desalination membranes, and the overall water production rate is controlled to be less than 50%.

[0021] As an embodiment of the invention, the anodic electrode is a titanium electrode coated with a nano iridium oxide coating on the surface, and the cathodic electrode in the cathode chamber is a titanium electrode;

[0022] Both the anodic electrode and the cathodic electrode are connected to a DC power supply through wires.

[0023] As an embodiment of the invention, the electrode spacing between the anodic electrode and the cathodic electrode is 1.2 cm, and the operating voltage of the DC power supply is 0 - 10 V.

[0024] As an embodiment of the invention, the startup stage includes:

[0025] Step S101: Inject the high-concentration and refractory organic wastewater to be treated into the coagulation sedimentation tank. After sequentially adding polyferric chloride and PAM in the coagulation sedimentation tank, adjust the pH to 9 - 10 with alkali for flocculation sedimentation to remove fine suspended solids and calcium, magnesium, and iron ions in the wastewater;

[0026] Step S102: The supernatant in Step S101 enters the two-stage DTRO treatment unit, and the permeate from the two-stage DTRO treatment unit is used as the water for the startup stage and enters the electrolytic cell;

[0027] Step S103: After the permeate enters the electrolytic cell, ozone is electrolyzed to form ozone water for the startup stage with a concentration of 18% - 20% and is discharged into the contact oxidation tank; the electrolytic cell consists of an anode chamber, a cathode chamber, and a PEM membrane, and the anodic electrode in the anode chamber is a nano-coated electrode.

[0028] The beneficial effects produced by adopting the above technical solution are as follows:

[0029] The deep treatment method for high-concentration and refractory organic wastewater provided by the present invention injects the high-concentration and refractory organic wastewater to be treated into the coagulation sedimentation tank. After sequentially adding polyferric chloride and PAM in the coagulation sedimentation tank, adjust the pH to 9 - 10 with alkali for flocculation sedimentation to remove fine suspended solids and calcium, magnesium, and iron ions in the wastewater; mix the supernatant with ozone water and discharge it into the contact oxidation tank, and use the heterogeneous ozone catalyst in the contact oxidation tank for catalytic oxidation to remove COD and ammonia nitrogen pollutants, so that the sewage reaches the discharge standard, and 90% - 95% of the qualified sewage is discharged; the remaining qualified sewage enters the two-stage DTRO treatment unit in sequence, and the concentrate generated by each stage of DTRO is discharged into the coagulation sedimentation tank, and the permeate from the two-stage DTRO treatment unit enters the electrolytic cell; after the permeate enters the electrolytic cell, ozone is electrolyzed to form ozone water with a concentration of 18% - 20% and is discharged into the contact oxidation tank; the electrolytic cell consists of an anode chamber, a cathode chamber, and a PEM membrane, and the anodic electrode in the anode chamber is a nano-coated electrode. It has the following beneficial effects:

[0030] (1)The equipment for the advanced treatment of high-concentration refractory organic wastewater only includes a coagulation sedimentation tank, a contact oxidation tank, a two-stage DTRO treatment unit, and an electrolytic cell. The equipment has a high degree of integration, and the degradation method is simple.

[0031] (2)Ozone is used as an oxidant, and its decomposition products are oxygen and water, which will not cause secondary pollution.

[0032] (3)The system is convenient to start and stop, has a short commissioning period, and can adjust operation parameters such as electrolytic voltage and ozone water volume according to water quality at any time.

[0033] (4)The energy utilization rate is high, and the ozone water concentration generated by the nano-coated electrode and PEM membrane electrolyzed water is high. Conventional electrolyzed water produces hydrogen and oxygen, and the ozone content obtained is very small. Using the PEM membrane, when direct current conducts the positive and negative poles of the PEM membrane, water is separated into hydrogen and oxygen elements in the form of proton exchange at the special anode solution interface. When the hydrogen element passes through the PEM membrane, energy exchange occurs, hydrogen is formed at the cathode and directly discharged from the solution interface. Oxygen molecules obtain energy due to the electron excitation generated by the high-density current at the anode interface and polymerize into ozone.

[0034] (5)The electrode has good corrosion resistance and a long service life. Description of the Drawings

[0035] Figure 1 is a schematic flow chart of an advanced treatment method for high-concentration refractory organic wastewater disclosed by the present invention. Detailed Embodiments

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be clearly and completely described below in conjunction with specific embodiments.

[0037] The embodiments of the present invention provide an advanced treatment method for high-concentration refractory organic wastewater, and the method includes:

[0038] Step 1: Inject the high-concentration refractory organic wastewater to be treated into the coagulation sedimentation tank. After sequentially adding polyferric chloride and PAM in the coagulation sedimentation tank, adjust the pH to 9-10 with alkali for flocculation sedimentation to remove fine suspended solids and calcium, magnesium, and iron ions in the wastewater, and the supernatant enters the next process;

[0039] In this step, the alkali used is sodium hydroxide; the dosage of polyferric chloride is 1000-2000 mg / L, the dosage of PAM is 1-2 mg / L, and sodium hydroxide is added to adjust the pH to 9-10. After flocculation sedimentation, the precipitated sludge is dehydrated and transported out, and the supernatant enters the next process.

[0040] Step 2: Mix the supernatant with ozone water and then discharge it into the contact oxidation tank. Use the heterogeneous ozone catalyst in the contact oxidation tank to catalytically oxidize and remove COD and ammonia nitrogen pollutants, so that the sewage meets the discharge standard. 90%-95% of the qualified sewage is discharged, and the remaining qualified sewage enters the next process;

[0041] To ensure the best catalytic oxidation effect, in the present invention, the heterogeneous ozone catalyst is composed of an aluminum-based ozone catalyst, a silicon-aluminum ozone catalyst, and a silicon-aluminum-titanium ozone catalyst mixed in a mass ratio of 1:3.5:0.5.

[0042] In addition, the present invention conducts catalytic oxidation on different influent water qualities and different effluent water qualities, and obtains the results shown in Table 1.

[0043] Table 1

[0044]

[0045] As can be seen from Table 1, the ozone dosage value is 1.24 - 1.45 times the theoretical ozone consumption. Therefore, in the present invention, the ozone amount value in the ozone water is obtained by the following formula: Q 臭氧 =[(influent COD value - effluent COD value) × 3 + (influent ammonia nitrogen value - effluent ammonia nitrogen value) × 5.33] × (1.24 - 1.45), where the influent COD value, effluent COD value, influent ammonia nitrogen value, and effluent ammonia nitrogen value are the influent water quality and effluent water quality of the contact oxidation tank.

[0046] For the sewage in this step to catalytically oxidize and remove COD and ammonia nitrogen pollutants, most of it is discharged, and a small part flows into the following process to generate ozone. The generated ozone is then returned to this step for repeated use. In this way, the purpose of saving energy can be achieved.

[0047] Step 3: The qualified sewage sequentially enters two-stage DTRO treatment units. The concentrate generated by each stage of DTRO is discharged into the coagulation sedimentation tank, and the permeate passing through the two-stage DTRO treatment units enters the electrolytic cell;

[0048] In this step, after adding a reducing agent to the qualified sewage, it sequentially enters two-stage DTRO treatment units. The reducing agent is sodium bisulfite, and the mass fraction of the reducing agent is 1.5%.

[0049] The first-stage DTRO treatment unit consists of a sand filter, a high-pressure pump, a first-stage DTRO membrane column, an on-line booster pump, and supporting pipelines and valves; the permeate of the first-stage DTRO enters the second-stage DTRO system. The second-stage DTRO treatment unit consists of a high-pressure pump, a second-stage DTRO membrane column, and supporting pipelines and valves;

[0050] The first-stage DTRO membrane column and the second-stage DTRO membrane column adopt the same DTRO membrane column structure, both including: RO membrane sheets, flow guide discs, O-ring rubber gaskets, central tie rods and membrane shells, and the RO membrane sheets are seawater desalination membranes. The overall water production rate is controlled to be lower than 50%, so as to ensure the water quality of the effluent.

[0051] Step 4: After the permeate enters the electrolytic cell, ozone is electrolyzed to form ozone water with a concentration of 18% - 20% and is discharged into the contact oxidation tank; the electrolytic cell consists of an anode chamber, a cathode chamber, and a PEM membrane, and the electrode anode in the anode chamber is a nano-coated electrode.

[0052] In this step, the electrode anode is a titanium electrode coated with a nano-iridium oxide coating on its surface, and the electrode cathode in the cathode chamber is a titanium electrode; both the electrode anode and the electrode cathode are connected to a DC power supply through wires.

[0053] Further, the electrode spacing between the electrode anode and the electrode cathode is 1.2 cm, and the operating voltage of the DC power supply is 0 - 10 V.

[0054] By changing the operating voltage of the DC power supply, the generation rate of ozone can be changed, and then the ozone content in the ozone water can be changed to form ozone water with a concentration of 18% - 20%; in addition, the ozone water obtained in this step will also flow back to the contact oxidation tank to catalytically oxidize and remove COD and ammonia nitrogen pollutants. The ozone amount in the ozone water in Step 2 can be jointly regulated by the ozone water flow rate and the ozone content in the ozone water, so that it meets the calculation formula of the aforementioned ozone amount Q 臭氧 to ensure that the sewage in the contact oxidation tank can reach the discharge standard.

[0055] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further elaborates on the invention with specific embodiments.

[0056] Example 1

[0057] The biochemical effluent of a sewage treatment station has a COD Cr = 1100 mg / L and NH₃-H = 60 mg / L. The advanced treatment method is as follows:

[0058] Step 1: Coagulation. Take the biochemical effluent, add polyferric chloride: 1000 mg / L, then add PAM: 1 mg / L, and then add sodium hydroxide: 2500 mg / L to adjust the pH to 9 - 10. After standing and sedimentation, the effluent has a COD Cr = 850 mg / L and NH₃-H = 50 mg / L.

[0059] Step 2: The biologically treated effluent undergoes flocculation and sedimentation and then enters the two-stage DTRO system as the water for the startup phase. The maximum water production of DTRO is 500 L / h. The produced water is temporarily stored in the water production tank.

[0060] Step 3: The DTRO-produced water enters the ozone water preparation unit. The voltage is set at 8 V, and the electrode spacing is 1.2 cm. Two electrode plates with dimensions of 5 cm × 5 cm and a thickness of 0.3 cm are used, and the PEM membrane has dimensions of 6 cm × 6 cm. The ozone water produced from the water is mixed with the sewage after coagulation and sedimentation and then enters the contact oxidation tank (wherein, the water for the startup phase in Step 2 during the startup phase is used to perform Step 3 to produce ozone water for the startup phase; during the circulation phase, Step 2 is not performed anymore).

[0061] Step 4: The catalyst in the contact oxidation tank is a composite heterogeneous ozone catalyst, which is composed of an aluminum-based ozone catalyst, a silicon-aluminum ozone catalyst, and a silicon-aluminum-titanium ozone catalyst. After being uniformly mixed in a mass ratio of 1:3.5:0.5, it is added to the ozone contact oxidation tank. The volume of the contact oxidation tank is 200 L, and the total volume of the catalyst is 100 L; the sewage after coagulation and sedimentation enters the contact oxidation tank at a flow rate of 100 L / h, and at the same time, ozone water is added. The concentration of the ozone water is 18%, and the flow rate is 2 L / h. The COD of the water produced after contact oxidation Cr = 40 mg / L, NH₃-H is not detected, and the pH drops to 6.5 - 7.5; the effluent meets the first-class A standard in "GB18918 - 2002" and can be directly discharged or reused.

[0062] Step 5: A part of the effluent after contact oxidation enters the DTRO unit to prepare the pure water required for electrolysis. The membrane concentrate is discharged to the front end of the pretreatment.

[0063] Example 2

[0064] The biologically treated effluent of a sewage treatment station has a COD Cr = 1300 mg / L and NH₃-H = 200 mg / L. Its advanced treatment method is as follows:

[0065] Step 1: Coagulation. For the biologically treated effluent, polyaluminum chloride is added at 2000 mg / L, then PAM is added at 2 mg / L, and then sodium hydroxide is added at 3000 mg / L to adjust the pH to 9 - 10. After standing and sedimentation, the effluent has a COD Cr = 910 mg / L and NH₃-H = 150 mg / L.

[0066] Step 2: The biologically treated effluent undergoes flocculation and sedimentation and then enters the two-stage DTRO system as the water for the startup phase. The maximum water production of DTRO is 500 L / h. The produced water is temporarily stored in the water production tank.

[0067] Step 3: The water produced by DTRO enters the ozone water preparation unit to obtain ozone water. Set the voltage to 10V and the electrode spacing to 1.2 cm. Two electrode plates with dimensions of 5 cm × 5 cm and a thickness of 0.3 cm are used, and the PEM membrane has dimensions of 6 cm × 6 cm. The ozone water is mixed with the sewage after coagulation and sedimentation and then enters the contact oxidation tank. (Among them, in the startup phase of Step 2, the water used in the startup phase is used to perform Step 3 to produce ozone water for the startup phase; in the circulation phase, Step 2 is no longer executed.)

[0068] Step 4: The catalyst in the contact oxidation tank is a composite heterogeneous ozone catalyst, which is composed of an aluminum-based ozone catalyst, a silicon-aluminum ozone catalyst, and a silicon-aluminum-titanium ozone catalyst. After mixing evenly according to a mass ratio of 1:3.5:0.5, it is added to the ozone contact oxidation tank. The volume of the contact oxidation tank is 200 L, and the total volume of the catalyst is 100 L. The sewage after coagulation and sedimentation in Step 1 enters the contact oxidation tank at a flow rate of 100 L / h, and at the same time, ozone water is added. The concentration of the ozone water is 18%, and the flow rate is 2.34 L / h. The COD of the water produced after contact oxidation Cr = 45 mg / L, NH3-H is not detected, and the pH drops to 6.5 - 7.5; the effluent meets the first-class A standard in "GB18918 - 2002" and can be directly discharged or reused.

[0069] Step 5: Part of the effluent after contact oxidation enters the DTRO unit to prepare the pure water required for electrolysis. The membrane concentrate is discharged to the front end of the pretreatment.

[0070] Example 3

[0071] The biochemical effluent of a sewage treatment plant has a COD Cr = 1000 mg / L and NH3-H = 500 mg / L. Its advanced treatment method is as follows

[0072] Step 1: Coagulation. Take the biochemical effluent, add anhydrous ferric chloride: 2000 mg / L, then add PAM: 2 mg / L, and then add sodium hydroxide: 3000 mg / L to adjust the pH to 9 - 10. After standing and sedimenting, the effluent COD Cr = 720 mg / L and NH3-H = 400 mg / L.

[0073] Step 2: The biochemical effluent enters the two-stage DTRO system after flocculation and sedimentation and is used as the water for the startup phase. The maximum water production of DTRO is 500 L / h. The produced water is temporarily stored in the water production tank.

[0074] Step 3: The DTRO-produced water enters the ozone water preparation unit. Set the voltage to 10 V and the electrode spacing to 1.2 cm. Two electrode plates with dimensions of 5 cm × 5 cm and a thickness of 0.3 cm are used, and the PEM membrane has dimensions of 6 cm × 6 cm. The ozone water produced from the water is mixed with the sewage after coagulation and sedimentation and then enters the contact oxidation tank. (Among them, in the startup stage of Step 2, the water used in the startup stage is used to execute Step 3 to produce ozone water for the startup stage; in the circulation stage, Step 2 is no longer executed.)

[0075] Step 4: The catalyst in the contact oxidation tank is a composite heterogeneous ozone catalyst, which is composed of an aluminum-based ozone catalyst, a silicon-aluminum ozone catalyst, and a silicon-aluminum-titanium ozone catalyst. After mixing evenly according to a mass ratio of 1:3.5:0.5, it is added to the ozone contact oxidation tank. The volume of the contact oxidation tank is 200 L, and the total volume of the catalyst is 100 L. The sewage after coagulation and sedimentation enters the contact oxidation tank at a flow rate of 100 L / h, and at the same time, ozone water is added. The concentration of the ozone water is 19%, and the flow rate is 3 L / h. The COD of the water produced after contact oxidation Cr = 38 mg / L, NH3-H is not detected, and the pH drops to 6.5 - 7.5; the effluent meets the first-class A standard in "GB18918-2002" and can be directly discharged or reused.

[0076] Step 5: Part of the effluent after contact oxidation enters the DTRO unit to prepare pure water required for electrolysis. The membrane concentrate is discharged to the front end of the pretreatment.

[0077] Example 4

[0078] The biochemical effluent of a sewage treatment plant has a COD Cr = 1000 mg / L and NH3-H = 500 mg / L. The advanced treatment method is as follows

[0079] Step 1: Coagulation. Take the biochemical effluent, add anhydrous ferric chloride: 2000 mg / L, then add PAM: 2 mg / L, and then add sodium hydroxide: 3000 mg / L to adjust the pH to 9 - 10. After standing and sedimentation, the COD of the effluent Cr = 720 mg / L and NH3-H = 400 mg / L.

[0080] Step 2: The biochemical effluent enters the two-stage DTRO system after flocculation and sedimentation and is used as the water for the startup stage. The maximum water production of DTRO is 500 L / h. The produced water is temporarily stored in the water production tank. (Among them, in the startup stage of Step 2, the water used in the startup stage is used to execute Step 3 to produce ozone water for the startup stage; in the circulation stage, Step 2 is no longer executed.)

[0081] Step 3: The DTRO-produced water enters the ozone water preparation unit, with a voltage of 10 V set and an electrode spacing of 1.2 cm. Two electrode plates with dimensions of 5 cm × 5 cm and a thickness of 0.3 cm are used, and the PEM membrane has dimensions of 6 cm × 6 cm. The ozone water produced from the water is mixed with the sewage after coagulation and sedimentation and then enters the contact oxidation tank.

[0082] Step 4: The catalyst in the contact oxidation tank is a composite heterogeneous ozone catalyst, which is composed of an aluminum-based ozone catalyst and a silicon-aluminum ozone catalyst. After being mixed evenly according to a mass ratio of 1:3.5, it is added to the ozone contact oxidation tank. The volume of the contact oxidation tank is 200 L, and the total volume of the catalyst is 100 L; the sewage after coagulation and sedimentation enters the contact oxidation tank at a flow rate of 100 L / h, and at the same time, ozone water is added. The concentration of the ozone water is 19%, and the flow rate is 3 L / h. The COD of the water produced after contact oxidation Cr = 60 mg / L, NH₃-H = 20 mg / L, and the pH drops to 7.5 - 8.0; the effluent does not meet the Class-A standard of "GB18918-2002".

[0083] Step 5: Part of the effluent after contact oxidation enters the DTRO unit to prepare the pure water required for electrolysis. The membrane concentrate is discharged to the front end of the pretreatment.

[0084] Example 5

[0085] The biochemical effluent of a sewage treatment station has a COD Cr = 1300 mg / L and NH₃-H = 200 mg / L, and its advanced treatment method is as follows

[0086] Step 1: Coagulation. For the biochemical effluent, polyferric chloride is added at 2000 mg / L, then PAM is added at 2 mg / L, and then sodium hydroxide is added at 3000 mg / L to adjust the pH to 9 - 10. After static sedimentation, the effluent has a COD Cr = 910 mg / L and NH₃-H = 150 mg / L.

[0087] Step 2: The biochemical effluent enters the two-stage DTRO system after flocculation and sedimentation and is used as the water for the startup stage. The maximum water production of DTRO is 500 L / h. The produced water is temporarily stored in the product water tank.

[0088] Step 3: The DTRO-produced water enters the ozone water preparation unit, with a voltage of 10 V set and an electrode spacing of 1.2 cm. Two electrode plates with dimensions of 5 cm × 5 cm and a thickness of 0.3 cm are used, and the PEM membrane has dimensions of 6 cm × 6 cm. The ozone water produced from the water is mixed with the sewage after coagulation and sedimentation and then enters the contact oxidation tank (wherein, the water for the startup stage in Step 2 during the startup stage is used to perform Step 3 to produce the ozone water for the startup stage; in the circulation stage, Step 2 is no longer executed).

[0089] Step 4: The catalyst in the contact oxidation tank is a composite heterogeneous ozone catalyst, which is composed of an aluminum-based ozone catalyst, a silica-aluminum ozone catalyst, and a silica-aluminum-titanium ozone catalyst. After being mixed evenly according to a mass ratio of 1:3.5:0.5, it is added to the ozone contact oxidation tank. The volume of the contact oxidation tank is 200 L, and the total volume of the catalyst is 100 L. The sewage after coagulation and sedimentation enters the contact oxidation tank at a flow rate of 100 L / h, and at the same time, ozone water is added. The concentration of the ozone water is 18%, and the flow rate is 1.78 L / h. After contact oxidation, the produced water has a COD Cr = 300 mg / L, NH3-H = 18 mg / L, and the pH drops to 7-8; the effluent does not meet the first-class A standard in "GB18918-2002".

[0090] Step 5: Part of the effluent after contact oxidation enters the DTRO unit to prepare the pure water required for electrolysis. The membrane concentrate is discharged to the front end of the pretreatment.

Claims

1. A method for deep treatment of high-concentration refractory organic wastewater, characterized in that: The equipment for deep treatment of high-concentration refractory organic wastewater includes a coagulation sedimentation tank, a contact oxidation tank, a two-stage DTRO treatment unit and an electrolytic tank, the contact oxidation tank has a volume of 200L, and the total volume of the heterogeneous ozone catalyst is 100L; the method includes a startup phase and a circulation phase, the startup phase is used to produce ozone water for the startup phase; The cycle stages include: Step 1: inject the high-concentration refractory organic wastewater to be treated into a coagulation sedimentation tank, add polyferric chloride and PAM in the coagulation sedimentation tank in sequence, adjust the pH to 9-10 with alkali for flocculation and sedimentation, remove fine suspended matter and calcium, magnesium and iron ions in the wastewater, and the supernatant enters the next process; Step 2: Mix the supernatant with ozone water and discharge it into a contact oxidation tank. Use the heterogeneous ozone catalyst in the contact oxidation tank to catalytically oxidize and remove COD and ammonia nitrogen pollutants, so that the sewage meets the discharge standards. 90%-95% of the sewage that meets the standards is discharged, and the remaining sewage that meets the standards enters the next process; Step 3: The remaining qualified sewage enters the two-stage DTRO treatment unit in turn, and the concentrated liquid produced by each stage of DTRO is discharged into the coagulation sedimentation tank, and the permeate of the two-stage DTRO treatment unit enters the electrolytic cell; Step 4: After the permeate enters the electrolytic cell, ozone is electrolyzed to form 18% to 20% ozone water which is discharged into the contact oxidation tank; the electrolytic cell is composed of an anode chamber, a cathode chamber, and a PEM membrane, and the anode electrode in the anode chamber is a nano-coated electrode; In step 2, the ozone value in ozone water is Q 臭氧 The following formula is used to obtain: Q 臭氧 =[(influent COD value - effluent COD value) × 3 + (influent ammonia nitrogen value - effluent ammonia nitrogen value) × 5.33] × (1.24 ~ 1.45); influent COD value, effluent COD value, influent ammonia nitrogen value, and effluent ammonia nitrogen value are all the influent water quality and effluent water quality of the contact oxidation tank; In step 4, the electrode anode is a titanium electrode coated with a nano-iridium oxide coating on the surface, the electrode cathode in the cathode chamber is a titanium electrode, and the electrode anode and the electrode cathode are both connected to a DC power supply through a wire; the electrode spacing between the electrode anode and the electrode cathode is 1.2 cm, and the operating voltage of the DC power supply is 0-10V; By changing the operating voltage of the DC power supply, the ozone generation rate is changed, and then the ozone content in the ozone water is changed to form 18%~20% ozone water; The ozone water obtained in step 4 will also flow back to the contact oxidation tank to catalytically oxidize and remove COD and ammonia nitrogen pollutants. The ozone amount in the ozone water in step 2 is jointly regulated by the ozone water flow rate and the ozone content in the ozone water so that it meets the ozone amount Q 臭氧 The calculation formula is used to ensure that the wastewater in the contact oxidation tank can meet the discharge standards.

2. A method for deep treatment of high-concentration refractory organic wastewater according to claim 1, characterized in that: In step 1, the alkali used is sodium hydroxide; the dosage of polyferric chloride is 1000-2000 mg / L, the dosage of PAM is 1-2 mg / L, and sodium hydroxide is added to adjust the pH to 9-10.

3. The method for deep treatment of high-concentration refractory organic wastewater according to claim 1, characterized in that: In step 2, the heterogeneous ozone catalyst is a mixture of an aluminum-based ozone catalyst, a silicon-aluminum ozone catalyst and a silicon-aluminum-titanium ozone catalyst in a mass ratio of 1:3.5:0.

5.

4. The method for deep treatment of high-concentration refractory organic wastewater according to claim 1, characterized in that: In step three, a reducing agent is added to the qualified wastewater and then enters a two-stage DTRO treatment unit in sequence, wherein the reducing agent is sodium bisulfite.

5. A method for deep treatment of high-concentration refractory organic wastewater according to claim 4, characterized in that: The mass fraction of the reducing agent is 1.5%.

6. The method for deep treatment of high-concentration refractory organic wastewater according to claim 1, characterized in that: In step 3, the first-stage DTRO treatment unit is composed of a sand filter, a high-pressure pump, a first-stage DTRO membrane column, an online booster pump, and supporting pipes and valves; the first-stage DTRO permeate enters the second-stage DTRO system, and the second-stage DTRO treatment unit is composed of a high-pressure pump, a second-stage DTRO membrane column, and supporting pipes and valves; The primary DTRO membrane column and the secondary DTRO membrane column adopt the same DTRO membrane column structure, both including: RO membrane, guide plate, O-type rubber gasket, central pull rod and membrane shell, and the RO membrane is a seawater desalination membrane, which controls the overall water production rate to be less than 50%.

7. The method for deep treatment of high-concentration refractory organic wastewater according to claim 1, characterized in that: The startup phase includes: Step S101, injecting the high-concentration refractory organic wastewater to be treated into a coagulation sedimentation tank, adding polyferric chloride and PAM in the coagulation sedimentation tank in sequence, and adjusting the pH to 9-10 with alkali for flocculation sedimentation to remove fine suspended matter and calcium, magnesium and iron ions in the wastewater; Step S102: The supernatant in step S101 enters a two-stage DTRO treatment unit, and the permeate from the two-stage DTRO treatment unit is used as water in the startup phase and enters the electrolytic cell; Step S103, after the permeate enters the electrolytic cell, ozone is electrolyzed to form 18% to 20% of ozone water for the startup phase, which is discharged into the contact oxidation tank; the electrolytic cell is composed of an anode chamber, a cathode chamber, and a PEM membrane, and the anode electrode in the anode chamber is a nano-coated electrode.

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