A wastewater treatment process and apparatus for tail gas scrubbing tower in the recycling process of waste polyester textiles.

Abstract

This invention discloses a wastewater treatment device and process. The device includes a homogenization tank, an anaerobic reactor, an MBR reactor, a pH adjustment tank, a Fenton reactor, a membrane tank, and an effluent tank connected sequentially by pipelines. The homogenization tank is used for homogenization and mixing with nutrients; the anaerobic reactor is used for anaerobic reactions; the MBR reactor is used for biochemical reactions to remove organic matter and total nitrogen; the pH adjustment tank is used to adjust the pH value; the effluent from the pH adjustment tank is mixed with iron salts and enters the Fenton reactor; the return water from the membrane tank is mixed with H2O2 and then enters the Fenton reactor, where it undergoes Fenton catalytic oxidation; the effluent from the Fenton reactor enters the membrane tank; alkali solution is added to the membrane tank under aeration conditions, and iron sludge is retained by the membrane module and returned to the Fenton reactor with the return water from the membrane tank. The device and process of this invention are designed for wastewater generated during the depolymerization process of waste polyester, and can achieve highly efficient removal of pollutants such as characteristic organic matter, ammonia nitrogen, total nitrogen, and antimony metal.

Description

Technical Field

[0001] This invention belongs to the field of chemical and environmental protection technology. Specifically, it relates to a treatment device for wastewater from a waste polyester textile recycling process tail gas scrubbing tower and a treatment process for wastewater from a waste polyester textile recycling process tail gas scrubbing tower. More specifically, it relates to a treatment device for wastewater from a waste polyester recycling depolymerization process and a treatment process for wastewater from a waste polyester recycling depolymerization process. Background Technology

[0002] The exhaust gases generated during the depolymerization process of waste polyester textiles must be treated by an exhaust gas scrubbing tower to meet emission standards. The wastewater from this scrubbing tower contains high concentrations of organic matter generated during polyester depolymerization, and its composition is complex. Because waste polyester also contains small amounts of impurities such as spandex, the degradation of spandex introduces nitrogenous pollutants into the wastewater system, resulting in high concentrations of ammonia nitrogen and total nitrogen. Furthermore, some heavy metals from the original heavy metal catalysts in the waste polyester enter the wastewater from the exhaust gas scrubbing tower during the depolymerization process, causing a series of problems for wastewater treatment.

[0003] CN109879545A discloses a process and method for treating high-salt, high-concentration organic wastewater, which treats TNT wastewater, MNT wastewater and DNT wastewater through "pretreatment (acid precipitation tank + micro-electrolysis tank + coagulation sedimentation tank) + vacuum distillation + biochemical treatment (GF / G-BAF process)". However, this process has a long flow and high power consumption.

[0004] CN210559871U discloses a polyester decolorization wastewater treatment device, which includes a dilution tank, a coarse filter tank, a fine filter tank, a distillation tank, a recovery tank, a clear water tank, and pipelines. The dilution tank, coarse filter tank, fine filter tank, and distillation tank are connected sequentially through a water supply pipeline. A pressure boosting pump is installed in the middle of the water supply pipeline. The distillation tank discharges the recovered liquid to the recovery tank through the recovery pipeline. The distillation tank discharges water vapor through a gas supply pipe, which is then condensed and fed into the clear water tank. This device can remove residues, pigments, and salts from the wastewater and separate and recover water from glycerol and oleic acid glycerides in the wastewater. However, this process is difficult to guarantee that the wastewater meets the discharge standards and cannot effectively remove pollutants such as heavy metals.

[0005] Currently, there is no treatment process specifically for pollutants generated during the depolymerization and recycling of waste polyester. Related processes for treating high-concentration organic wastewater also cannot specifically remove the characteristic pollutants generated during the wastewater recycling and depolymerization process. Therefore, this invention studies the wastewater generated during the wastewater recycling and depolymerization process and develops a process and apparatus for the efficient removal of characteristic pollutants from the wastewater. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention provides a novel wastewater treatment device and process for a tail gas scrubbing tower during the recycling of waste polyester textiles. This device and process can efficiently remove pollutants such as characteristic organic matter, ammonia nitrogen, total nitrogen, and antimony metal from the wastewater generated during the depolymerization process of waste polyester recycling.

[0007] The first aspect of this invention provides a wastewater treatment device, comprising a homogenizing tank, an anaerobic reactor, an MBR reactor, a pH adjustment tank, a Fenton reactor, a membrane tank, and an effluent tank connected sequentially by pipelines. The homogenizing tank is used for homogenization and mixing with nutrients. The anaerobic reactor is used for anaerobic reactions to remove organic matter from the wastewater and decompose recalcitrant organic matter into smaller organic molecules. The MBR reactor is used for biochemical reactions to remove organic matter and total nitrogen from the wastewater. The pH adjustment tank is used to adjust the pH value. The effluent from the pH adjustment tank is mixed with iron salts and enters the Fenton reactor. The return water from the membrane tank is mixed with H2O2 and then enters the Fenton reactor. The Fenton reactor is used for Fenton catalytic oxidation. The effluent from the Fenton reactor enters the membrane tank. Alkali solution is added to the membrane tank under aeration conditions. Iron sludge is retained by the membrane module and returned to the Fenton reactor with the return water from the membrane tank. The effluent from the membrane tank enters the effluent tank.

[0008] According to some embodiments of the apparatus of the present invention, in order to reduce the adverse effects of fluctuations in production process conditions on wastewater treatment, the waste polyester regeneration depolymerization wastewater is first sent to a homogenization tank for pH adjustment and regulation of nutrient salt content such as N and P.

[0009] According to some embodiments of the apparatus described in this invention, the anaerobic reactor may be a UASB reactor, an IC reactor, or an EGSB reactor, etc.

[0010] According to some embodiments of the apparatus of the present invention, the sludge inoculated in the anaerobic reactor is anaerobic granular sludge.

[0011] According to some embodiments of the apparatus of the present invention, modified polyurethane packing is added to the reaction zone of the MBR reactor, wherein the surface of the packing is aerobic and the interior is oxygen-deficient.

[0012] According to some embodiments of the apparatus of the present invention, the specific surface area of ​​the modified polyurethane filler is 20,000-30,000 m². 2 / m 3 .

[0013] According to some embodiments of the device of the present invention, preferably, the preparation method of the modified polyurethane filler includes: subjecting the polyurethane filler to surface oxidation treatment with an oxidant (to increase its roughness); dispersing the obtained oxidized polyurethane filler, biomass activated carbon powder and cationic water treatment agent uniformly under ultrasonic conditions for 30-60 min, and then drying at a constant temperature of 90-110℃; stirring and impregnating the dried polyurethane filler in a modified coating agent for 30-60 min, and then curing it in a constant temperature oven at 105-120℃.

[0014] According to some embodiments of the apparatus of the present invention, preferably, the oxidant is potassium permanganate, concentrated sulfuric acid, concentrated nitric acid, etc.

[0015] According to some embodiments of the device described in this invention, preferably, the activated carbon is biomass activated carbon.

[0016] According to some embodiments of the device of the present invention, preferably, a cationic water treatment agent is prepared under the conditions of triethylamine as solvent, pyridine as catalyst, and epichlorohydrin as etherifying agent, which activates biomass activated carbon powder and effectively combines it with polyurethane filler, thereby improving the adsorption capacity of the filler for organic matter and nitrate.

[0017] According to some embodiments of the apparatus of the present invention, preferably, the modified coating agent comprises carboxylated chitosan, sodium carboxymethyl cellulose, acrylic acid, silicone wetting agent, water, and optionally low-density polyolefin microparticles. Preferably, based on 100 parts by weight of the modified coating agent, the solution comprises 5-10 parts by weight of carboxylated chitosan, 0-10 parts by weight of low-density polyolefin microparticles, 0.2-1 parts by weight of sodium carboxymethyl cellulose, 1-10 parts by weight of acrylic acid, 0.2-1 parts by weight of silicone wetting agent, and 68-93.6 parts by weight of tap water.

[0018] According to some embodiments of the apparatus of the present invention, a microfiltration membrane is provided in the MBR reactor, preferably, the membrane pore size is 0.1-0.5 μm.

[0019] According to some embodiments of the apparatus of the present invention, iron salt and H2O2 are added separately to avoid ineffective waste of oxidant. By controlling the H2O2 metering pump, H2O2 is gradually and continuously added to the reaction system, which effectively maintains a stable and high hydrogen peroxide concentration in the system, ensures the continuous and effective generation of ·OH, ensures a high chemical reaction rate, and effectively reduces the ineffective decomposition of H2O2, thereby reducing the amount of H2O2 required.

[0020] In some embodiments of the apparatus according to the present invention, the catalyst in the Fenton reactor is an iron salt.

[0021] According to some embodiments of the device described in this invention, the alkali solution in the alkali solution tank is introduced into the membrane tank by an alkali solution metering pump for pH adjustment.

[0022] According to some embodiments of the apparatus described in this invention, in the membrane tank, the membrane module is an ultrafiltration membrane with a pore size of 0.05-0.2 μm. The membrane module used for sludge-water separation is an ultrafiltration membrane, which can be a flat sheet membrane, hollow fiber membrane, ceramic membrane, etc., and the aeration device is located directly below the membrane module. After Fenton treatment, the effluent enters the membrane tank. Under the conditions of strong aeration and appropriate alkaline pH in the membrane tank, the ultrafiltration membrane can effectively retain iron sludge and large molecular colloidal pollutants, ensuring that the effluent meets discharge standards or is reused.

[0023] According to some embodiments of the apparatus described in this invention, the wastewater treatment device is used for treating wastewater from the depolymerization process of waste polyester regeneration, wherein the wastewater has a pH of 7-9, a COD of 50,000-800,000 mg / L, a TN of 100-800 mg / L, an ammonia nitrogen concentration of 100-800 mg / L, and an antimony concentration of 1-10 mg / L. The main organic pollutants in the wastewater include benzene compounds, methanol, esters, and antimony metal.

[0024] According to some specific embodiments of the device described in this invention, the wastewater treatment device mainly includes, in sequence, a homogenization tank 1, an anaerobic reactor 2, an MBR reactor 3, a pH adjustment tank 4, a Fenton reactor 5, a membrane tank 6, and an effluent tank 7. Wastewater is fed into the homogenization tank 1, which is equipped with a stirring device. The effluent from the homogenization tank 1 is connected to the bottom inlet of the anaerobic reactor 2 via a pipeline. The effluent from the anaerobic reactor 2 is connected to the inlet of the MBR reactor 3 via a pipeline. The effluent from the MBR reactor 3 is connected to the inlet of the pH adjustment tank 4 via a pipeline. The effluent from the pH adjustment tank 4 is then mixed with iron salts (Fe... 2+ The metering pump outlet is connected via a pipeline, and the mixture enters the bottom inlet of Fenton reactor 5. The effluent from Fenton reactor 5 is connected to the inlet of membrane tank 6 via a pipeline, and the return effluent from membrane tank 6 is connected to the outlet of H2O2 metering pump via a pipeline. The mixture enters the bottom return port of Fenton reactor 5. The permeate pump connected to membrane tank 6 discharges compliant effluent into effluent tank 7, where it is either discharged externally or reused.

[0025] The second aspect of this invention provides a treatment process for wastewater from a tail gas scrubbing tower in the recycling process of waste polyester textiles, comprising: passing the wastewater sequentially through a homogenizing tank, an anaerobic reactor, an MBR reactor, a pH adjustment tank, a Fenton reactor, a membrane tank, and an effluent tank, wherein: homogenization and mixing with nutrients are performed in the homogenizing tank; an anaerobic reaction is carried out in the anaerobic reactor to remove organic matter from the wastewater and decompose recalcitrant organic matter into smaller organic molecules; a biochemical reaction for removing organic matter and total nitrogen is carried out in the MBR reactor to remove organic matter and total nitrogen from the wastewater; the pH value is adjusted in the pH adjustment tank; the effluent from the pH adjustment tank is mixed with iron salts and enters the Fenton reactor, and the return water from the membrane tank is mixed with H2O2 and then enters the Fenton reactor, where a Fenton catalytic oxidation reaction is carried out, and the effluent from the Fenton reactor enters the membrane tank; in the membrane tank, an alkaline solution is added under aeration conditions, and the iron sludge is retained by the membrane module and returned to the Fenton reactor with the return water from the membrane tank, and the effluent from the membrane tank enters the effluent tank.

[0026] According to some embodiments of the process described in this invention, the pH is adjusted to 7-8 in the homogenization tank. The acid used to adjust the pH can be HCl or HNO3; the alkali used to adjust the pH can be NaOH.

[0027] According to some embodiments of the process described in this invention, N nutrient salts and / or P nutrient salts are added to the homogenization tank to ensure the N and P trace element requirements of subsequent biochemical treatment.

[0028] In some embodiments of the process described in this invention, the nitrogen nutrient is urea.

[0029] According to some embodiments of the process described in this invention, the amount added, calculated as N, is 90-100 mg / L.

[0030] In some embodiments of the process described in this invention, the P nutrient salt is potassium dihydrogen phosphate.

[0031] According to some embodiments of the process described in this invention, the amount added is 3-5 mg / L, calculated as P.

[0032] According to some embodiments of the process described in this invention, the hydraulic retention time in the homogenizing tank is 1-5 hours.

[0033] According to some embodiments of the process described in this invention, the COD volumetric loading in the anaerobic reactor is 2-20 kg / m³. 3 d. The homogenized wastewater is sent to an anaerobic reactor for efficient anaerobic reaction to effectively remove organic matter from the wastewater and decompose recalcitrant macromolecular organic matter into smaller molecular organic matter. The COD volumetric loading rate in the anaerobic reactor is 2-20 kg / m³. 3•d, the effluent recirculation ratio is set according to the concentration and treatment load, the hydraulic retention time is 10-25h, and the generated methane can be recycled.

[0034] According to some embodiments of the process described in this invention, the hydraulic retention time in the anaerobic reactor is 10-25 h.

[0035] According to some embodiments of the process described in this invention, the temperature of the anaerobic reactor is 20-35℃. The effluent from the anaerobic reaction is sent to the MBR reactor, which can efficiently remove organic matter from the wastewater. Modified polyurethane packing is added to the reaction zone; the surface of the packing is aerobic, while the interior is anoxic, enabling simultaneous removal of total nitrogen and ammonia nitrogen and helping to prevent membrane fouling. The hydraulic retention time of the reactor is 12-24 hours.

[0036] According to some embodiments of the process described in this invention, modified polyurethane packing is added to the reaction zone of the MBR reactor, preferably at a volume ratio of 10-30%.

[0037] According to some embodiments of the process described in this invention, preferably, the preparation method of the modified polyurethane filler includes: subjecting the polyurethane filler to surface oxidation treatment with an oxidant (to increase its roughness); dispersing the obtained oxidized polyurethane filler, biomass activated carbon powder, and cationic water treatment agent uniformly under ultrasonic conditions for 30-60 min, and then drying at a constant temperature of 90-110℃; stirring and impregnating the dried polyurethane filler in a modified coating agent for 30-60 min, and then curing it in a constant temperature oven at 105-120℃.

[0038] According to some embodiments of the process described in this invention, preferably, the oxidant is potassium permanganate, concentrated sulfuric acid, concentrated nitric acid, etc.

[0039] According to some embodiments of the process described in this invention, preferably, the activated carbon is biomass activated carbon.

[0040] According to some embodiments of the apparatus of the present invention, preferably, a cationic water treatment agent is prepared under conditions of triethylamine as solvent, pyridine as catalyst, and epichlorohydrin as etherifying agent. This activates biomass activated carbon powder and effectively combines it with polyurethane filler, thereby improving the adsorption capacity of the filler for organic matter and nitrate. The preparation conditions include a temperature of 30-50°C and a time of 0.5-1 h. Specifically, for example, but not limited to, the cationic water treatment agent is prepared under conditions of 80 parts by weight of triethylamine as solvent, 10 parts by weight of pyridine as catalyst, and 10 parts by weight of epichlorohydrin as etherifying agent.

[0041] According to some embodiments of the process described in this invention, preferably, the modified coating agent comprises carboxylated chitosan, sodium carboxymethyl cellulose, acrylic acid, silicone wetting agent, water, and optionally low-density polyolefin microparticles. Preferably, based on 100 parts by weight of the modified coating agent, the solution comprises 5-10 parts by weight of carboxylated chitosan, 0-10 parts by weight of low-density polyolefin microparticles, 0.2-1 parts by weight of sodium carboxymethyl cellulose, 1-10 parts by weight of acrylic acid, 0.2-1 parts by weight of silicone wetting agent, and 68-93.6 parts by weight of tap water.

[0042] According to some embodiments of the process described in this invention, a microfiltration membrane with a pore size of 0.1-0.5 μm is provided in the MBR reactor for mud-water separation.

[0043] According to some embodiments of the process described in this invention, the pH is adjusted to 2-4.5 in a pH adjustment tank.

[0044] According to some embodiments of the process described in this invention, the acid used to adjust the pH is H2SO4, more preferably 8-12% by weight of H2SO4, and even more preferably 10% by weight of H2SO4.

[0045] According to some embodiments of the process described in this invention, the H2O2 concentration is 25-30% by weight, preferably 27.5% by weight.

[0046] According to some embodiments of the process described in this invention, H2O2 is added at a rate of 0.5-6 g per liter of wastewater. Under acidic conditions, iron salts can be used as catalysts to generate highly active hydroxyl radicals (·OH), which initiate and propagate a series of chain reactions, rapidly oxidizing and decomposing organic pollutants in the wastewater into carbon dioxide and water.

[0047] According to some embodiments of the process described in this invention, the iron salt concentration in the Fenton reactor, calculated as iron, is controlled at 40-400 mg per liter of wastewater.

[0048] In some embodiments of the process described in this invention, the iron salt is FeSO4.

[0049] According to some embodiments of the process described in this invention, the hydraulic retention time of the Fenton reactor is 0.5-2 hours.

[0050] According to some embodiments of the process described in this invention, the pH value in the membrane tank is adjusted to a slightly alkaline state, preferably to 7-9. NaOH is preferred as the alkali. The alkali solution in the alkali tank is introduced into the membrane tank via an alkali metering pump for pH adjustment. Heavy metals such as antimony in the wastewater can precipitate with the iron sludge. After the iron sludge is intercepted by the membrane module, it returns to the bottom reflux port of the Fenton reactor with the reflux liquid to continue the Fenton catalytic oxidation reaction. Fe salt is added as needed.

[0051] According to some embodiments of the process described in this invention, the effluent from the membrane tank is discharged through a permeate pump and enters an effluent tank for discharge or reuse after meeting standards.

[0052] According to some embodiments of the process described in this invention, the wastewater treatment device is used to treat wastewater from the depolymerization process of waste polyester regeneration, wherein the wastewater has a pH of 7-9, a COD of 50,000-800,000 mg / L, a TN of 100-800 mg / L, an ammonia nitrogen concentration of 100-800 mg / L, and an antimony concentration of 1-10 mg / L. The main organic pollutants in the wastewater include benzene compounds, methanol, esters, and antimony metal.

[0053] According to some specific embodiments of the process described in this invention, wastewater from the depolymerization of recycled polyester enters a homogenization tank through an inlet pipe for homogenization and mixing with nutrients. After homogenization, the wastewater is sent to an anaerobic reactor for anaerobic reaction to remove organic matter and decompose recalcitrant organic matter into smaller organic molecules. The effluent from the anaerobic reactor enters an MBR reactor for biochemical reactions to remove organic matter and total nitrogen, thus removing organic matter and total nitrogen from the wastewater. The effluent from the MBR reactor is further pH-adjusted by adding iron salts (Fe). 2+ The return water from the membrane tank is mixed with the H2O2 return water and then enters the Fenton reactor for catalytic oxidation. The effluent from the Fenton reactor enters the membrane tank and is neutralized by adding alkali solution (pH to 7-9) under aeration conditions. The neutralized iron sludge is retained by the membrane module and returned to the bottom of the Fenton reactor with the return water. The effluent meets the standards for discharge or reuse.

[0054] The beneficial effects of this invention are:

[0055] (1) This invention is designed for wastewater from the depolymerization process of waste polyester recycling, and can achieve efficient removal of heavy metal pollutants such as organic matter, ammonia nitrogen, total nitrogen, and antimony.

[0056] (2) The MBR reactor of this invention uses modified polyurethane packing, which has a large specific surface area, good hydrophilicity, high roughness, and is easy to attach to a biofilm.

[0057] (3) In the MBR reactor of the present invention, the packing surface is aerobic and the interior is hypoxic, which can achieve the simultaneous removal of total nitrogen and ammonia nitrogen and reduce the fouling of microfiltration membrane.

[0058] (4) In this invention, the iron sludge from the membrane tank is returned to the Fenton reactor to maintain a high iron sludge concentration in the entire system. After being mixed with the incoming water, it undergoes Fenton catalytic oxidation reaction, thereby effectively reducing the amount of catalyst added, improving oxidation efficiency, and reducing operating costs and the amount of iron sludge generated.

[0059] (5) Using the waste textile recycling process tail gas scrubbing tower device and process of the present invention, wastewater is fed into an anaerobic reactor after homogenization and conditioning for anaerobic reaction to remove organic matter and decompose recalcitrant organic matter into small molecule organic matter. After anaerobic treatment, the wastewater enters an MBR reactor using modified polyurethane packing. The packing has a large specific surface area, good hydrophilicity, and is easy to attach to a membrane, which can simultaneously remove total nitrogen and ammonia nitrogen and reduce microfiltration membrane fouling. The membrane Fenton oxidation process effectively removes organic matter and heavy metal pollutants such as antimony from the wastewater, which can effectively reduce the amount of catalyst added and improve oxidation efficiency.

[0060] (6) The membrane Fenton oxidation of the present invention can effectively reduce the amount of catalyst added, improve the oxidation efficiency, reduce the amount of iron sludge produced, and reduce the operating cost. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the wastewater treatment device for the tail gas scrubbing tower in the waste polyester textile recycling process provided in Embodiment 1 of the present invention.

[0062] Explanation of reference numerals in the attached figures

[0063] 1. Homogenizing tank; 2. Anaerobic reactor; 3. MBR reactor; 4. pH adjustment tank; 5. Fenton reactor; 6. Membrane tank; 7. Effluent tank. Detailed Implementation

[0064] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0065] The testing method and equipment used in this invention are as follows:

[0066]

Example 1

[0067] Adopting such Figure 1The wastewater treatment device shown is a tail gas scrubbing tower for the waste polyester textile recycling process. This device consists of a homogenization tank 1, an anaerobic reactor 2, an MBR reactor 3, a pH adjustment tank 4, a Fenton reactor 5, a membrane tank 6, and an effluent tank 7, connected sequentially by pipelines. The homogenization tank 1 is used for homogenization and mixing with nutrients; the anaerobic reactor 2 is used for anaerobic reactions to remove organic matter from the wastewater and decompose recalcitrant organic matter into smaller organic molecules; the MBR reactor 3 is used for removing organic matter and total nitrogen. The biochemical reaction removes organic matter and total nitrogen from the wastewater; the pH adjustment tank 4 is used to adjust the pH value; the effluent from the pH adjustment tank is mixed with iron salt and enters the Fenton reactor 5, the return water from the membrane tank is mixed with H2O2 and then enters the Fenton reactor 5, the Fenton reactor 5 is used to carry out the Fenton catalytic oxidation reaction, the effluent from the Fenton reactor 5 enters the membrane tank 6; alkaline solution is added to the membrane tank 6 under aeration conditions, the iron sludge is intercepted by the membrane module and returned to the Fenton reactor 5 with the return water from the membrane tank, and the effluent from the membrane tank enters the effluent tank 7.

[0068] The sludge inoculated into the anaerobic reactor is anaerobic granular sludge. Modified polyurethane packing is added to the reaction zone of the MBR reactor. Alkali solution from the alkali tank is pumped into the membrane tank for pH adjustment via an alkali metering pump.

[0069]

Example 2

[0070] Wastewater was treated using the wastewater treatment device described in Example 1. The wastewater was depolymerization wastewater from waste polyester regeneration, with a pH of 8.2, COD of 8300 mg / L, TN of 450 mg / L, ammonia nitrogen of 330 mg / L, and antimony concentration of 3.3 mg / L. The reactor process parameters were as follows:

[0071] (1) Waste polyester regeneration depolymerization wastewater is sent to a homogenization tank, acid is added to adjust the pH to 7.5, the concentration of urea (as N) is 94 mg / L, the concentration of potassium dihydrogen phosphate (as P) is 3.8 mg / L, and the hydraulic retention time is 1 h.

[0072] (2) The homogenized wastewater is sent to an anaerobic reactor to effectively remove organic matter from the wastewater. The sludge inoculated in the anaerobic reactor is anaerobic granular sludge. The temperature in the anaerobic reactor is 28℃, the hydraulic retention time is 10h, and the COD volumetric loading rate is 6kg / m³. 3 The methane produced can be recycled.

[0073] (3) The effluent from the anaerobic reactor is sent to the MBR reactor, which is equipped with a microfiltration membrane with a pore size of 0.1-0.5 μm for mud-water separation. The modified polyurethane packing is added at a ratio of 12% by volume, with a specific surface area of ​​20,000 m². 2 / m 3The polyurethane filler was first surface-oxidized with potassium permanganate solution to increase its roughness. After oxidation, 50g of the polyurethane filler and 8g of biomass activated carbon powder were immersed in a cationic water treatment agent (80 parts by weight of triethylamine, 10 parts by weight of pyridine, 10 parts by weight of epichlorohydrin, 40℃, 1 hour to prepare the cationic water treatment agent). The mixture was then ultrasonically dispersed for 30 minutes, followed by drying at a constant temperature of 110℃. The dried polyurethane filler was then stirred and impregnated in a modified coating agent for 40 minutes, and cured in a constant temperature oven at 105℃. The modified coating agent, by weight (100 parts), contained 5.4 parts by weight of carboxylated chitosan, 1 part by weight of low-density polyolefin microparticles, 0.4 parts by weight of sodium carboxymethyl cellulose, 2 parts by weight of acrylic acid, 0.3 parts by weight of silicone wetting agent, and 90.9 parts by weight of tap water.

[0074] (4) The effluent from the MBR reactor is sent to the pH adjustment tank to adjust the pH to 2. The iron salt concentration is controlled at 80 mg (Fe) per liter of wastewater. The amount of H2O2 is added at 2 g per liter of wastewater. The hydraulic retention time of the Fenton reactor is 0.7 h.

[0075] (5) The effluent from the Fenton reactor enters the membrane tank, and NaOH solution is added to adjust the pH to 7. The pore size of the ultrafiltration membrane is 0.05-0.2μm. After the iron sludge is intercepted by the membrane module, it returns to the bottom of the Fenton reactor with the reflux liquid to continue the catalytic reaction. The effluent from the membrane tank is discharged through the product water pump and enters the effluent tank for discharge or reuse after meeting the standards.

[0076] Specifically, after the above treatment steps, the effluent COD is 79 mg / L, the effluent ammonia nitrogen is 4.5 mg / L, the total nitrogen is 28.3 mg / L, and the antimony concentration is 0.23 mg / L, which meets the discharge standards.

[0077]

Example 3

[0078] Wastewater was treated using the wastewater treatment device described in Example 1. The wastewater was depolymerization wastewater from waste polyester recycling, with a pH of 8.0, COD of 42000 mg / L, TN of 480 mg / L, ammonia nitrogen of 440 mg / L, and antimony concentration of 5.6 mg / L. The reactor process parameters were as follows:

[0079] (1) Waste polyester regeneration depolymerization wastewater is sent to a homogenization tank for water quality adjustment. The concentration of urea (as N) is 92 mg / L, the concentration of potassium dihydrogen phosphate (as P) is 3.2 mg / L, and the hydraulic retention time is 1.5 h.

[0080] (2) The homogenized wastewater is sent to an anaerobic reactor to effectively remove organic matter from the wastewater. The sludge inoculated in the anaerobic reactor is anaerobic granular sludge. The temperature in the anaerobic reactor is 30℃, the hydraulic retention time is 14h, and the COD volumetric loading rate is 9kg / m³. 3 The methane produced can be recycled.

[0081] (3) The effluent from the anaerobic reactor is sent to the MBR reactor, which is equipped with a microfiltration membrane with a pore size of 0.1-0.5 μm for mud-water separation. The modified polyurethane packing is added at a ratio of 15% by volume, with a specific surface area of ​​22000 m². 2 / m 3 The polyurethane filler was first surface-oxidized with concentrated sulfuric acid solution to increase its roughness. After oxidation, 60g of the polyurethane filler and 10g of biomass activated carbon powder were immersed in a cationic water treatment agent (the preparation method of the cationic water treatment agent is the same as in Example 2) and dispersed evenly under ultrasonic conditions for 40 minutes, followed by drying at a constant temperature of 100℃. The dried polyurethane filler was then stirred and impregnated in a modified coating agent for 45 minutes, and cured in a constant temperature oven at 110℃. The modified coating agent, by weight (100 parts), contained 6.5 parts carboxylated chitosan, 3 parts low-density polyolefin microparticles, 0.5 parts sodium carboxymethyl cellulose, 4 parts acrylic acid, 0.4 parts silicone wetting agent, and 85.6 parts tap water.

[0082] (4) The effluent from the MBR reactor is sent to the pH adjustment tank to adjust the pH to 2.4. The iron salt concentration is controlled at 190 mg (Fe) per liter of wastewater. The amount of H2O2 is added at 3.1 g per liter of wastewater. The hydraulic retention time of the Fenton reactor is 0.8 h.

[0083] (5) The effluent from the Fenton reactor enters the membrane tank, and NaOH solution is added to adjust the pH to 7.5. The pore size of the ultrafiltration membrane is 0.05-0.2μm. After the iron sludge is intercepted by the membrane module, it returns to the bottom of the Fenton reactor with the reflux liquid to continue the catalytic reaction. The effluent from the membrane tank is discharged through the product water pump and enters the effluent tank for discharge or reuse after meeting the standards.

[0084] Specifically, after the above treatment steps, the effluent COD is 75 mg / L, the effluent ammonia nitrogen is 4.2 mg / L, the total nitrogen is 29.6 mg / L, and the antimony concentration is 0.32 mg / L, which meets the discharge standards.

[0085]

Example 4

[0086] Wastewater was treated using the wastewater treatment device described in Example 1. The wastewater was depolymerization wastewater from recycled polyester, with a pH of 8.2, COD of 250,000 mg / L, TN of 590 mg / L, ammonia nitrogen of 550 mg / L, and antimony concentration of 7.3 mg / L. The reactor process parameters were as follows:

[0087] (1) Wastewater from the depolymerization of recycled polyester was sent to a homogenizing tank for water quality adjustment. The concentration of urea (as N) was 95 mg / L, the concentration of potassium dihydrogen phosphate (as P) was 4 mg / L, and the hydraulic retention time was 2 h.

[0088] (2) The homogenized wastewater is sent to an anaerobic reactor to effectively remove organic matter from the wastewater. The sludge inoculated in the anaerobic reactor is anaerobic granular sludge. The temperature in the anaerobic reactor is 32℃, the hydraulic retention time is 18h, and the COD volumetric loading rate is 13kg / m³. 3 The methane produced can be recycled.

[0089] (3) The effluent from the anaerobic reactor is sent to the MBR reactor, which is equipped with a microfiltration membrane with a pore size of 0.1-0.5 μm for mud-water separation. The modified polyurethane packing is added at a ratio of 20% by volume, with a specific surface area of ​​25,000 m². 2 / m 3 The polyurethane filler was first surface-oxidized with potassium permanganate solution to increase its roughness. After oxidation, 40g of the polyurethane filler and 7g of biomass activated carbon powder were immersed in a cationic water treatment agent (the preparation method of the cationic water treatment agent is the same as in Example 2) and dispersed evenly under ultrasonic conditions for 45 minutes, followed by drying at a constant temperature of 105℃. The dried polyurethane filler was then stirred and impregnated in a modified coating agent for 50 minutes, and cured in a constant temperature oven at 115℃. The modified coating agent, by weight (100 parts), contained 7.8 parts carboxylated chitosan, 5 parts low-density polyolefin microparticles, 0.6 parts sodium carboxymethyl cellulose, 6 parts acrylic acid, 0.6 parts silicone wetting agent, and 80 parts tap water.

[0090] (4) The effluent from the MBR reactor is sent to the pH adjustment tank to adjust the pH to 3. The iron salt concentration is controlled at 220 mg (Fe) per liter of wastewater. The amount of H2O2 is added at 3.5 g per liter of wastewater. The hydraulic retention time of the Fenton reactor is 1 hour.

[0091] (5) The effluent from the Fenton reactor enters the membrane tank, and NaOH solution is added to adjust the pH to 8. The pore size of the ultrafiltration membrane is 0.05-0.2μm. After the iron sludge is intercepted by the membrane module, it returns to the bottom of the Fenton reactor with the reflux liquid to continue the catalytic reaction. The effluent from the membrane tank is discharged through the product water pump and enters the effluent tank for discharge or reuse after meeting the standards.

[0092] Specifically, after the above treatment steps, the effluent COD is 78 mg / L, the effluent ammonia nitrogen is 4.4 mg / L, the total nitrogen is 27.8 mg / L, and the antimony concentration is 0.21 mg / L, which meets the discharge standards.

[0093]

Example 5

[0094] Wastewater was treated using the wastewater treatment device described in Example 1. The wastewater was depolymerization wastewater from recycled polyester, with a pH of 8.2, COD of 530,000 mg / L, TN of 640 mg / L, ammonia nitrogen of 620 mg / L, and antimony concentration of 8.4 mg / L. The reactor process parameters were as follows:

[0095] (1) Waste polyester regeneration depolymerization wastewater is sent to a homogenization tank for water quality adjustment. The concentration of urea (as N) is 96 mg / L, the concentration of potassium dihydrogen phosphate (as P) is 4.5 mg / L, and the hydraulic retention time is 2 h.

[0096] (2) The homogenized wastewater is sent to an anaerobic reactor to effectively remove organic matter from the wastewater. The sludge inoculated in the anaerobic reactor is anaerobic granular sludge. The temperature in the anaerobic reactor is 33℃, the hydraulic retention time is 20h, and the COD volumetric loading rate is 18kg / m³. 3 The methane produced can be recycled.

[0097] (3) The effluent from the anaerobic reactor is sent to the MBR reactor, which is equipped with a microfiltration membrane with a pore size of 0.1-0.5 μm for mud-water separation. The modified polyurethane packing is added at a ratio of 25% by volume, with a specific surface area of ​​27,000 m². 2 / m 3 The polyurethane filler was first surface-oxidized with potassium permanganate solution to increase its roughness. 70g of the oxidized polyurethane filler and 12g of biomass activated carbon powder were then immersed in a cationic water treatment agent (the preparation method of the cationic water treatment agent is the same as in Example 2) and dispersed evenly under ultrasonic conditions for 50 minutes, followed by drying at a constant temperature of 90°C. The dried polyurethane filler was then stirred and impregnated in a modified coating agent for 55 minutes, and cured in a constant temperature oven at 120°C. The modified coating agent, by weight (100 parts), contained 8.4 parts carboxylated chitosan, 7 parts low-density polyolefin microparticles, 0.8 parts sodium carboxymethyl cellulose, 7 parts acrylic acid, 0.8 parts silicone wetting agent, and 76 parts tap water.

[0098] (4) The effluent from the MBR reactor is sent to the pH adjustment tank to adjust the pH to 3.5. The iron salt concentration is controlled at 280 mg (Fe) per liter of wastewater. The amount of H2O2 is added at 4.9 g per liter of wastewater. The hydraulic retention time of the Fenton reactor is 1.5 h.

[0099] (5) The effluent from the Fenton reactor enters the membrane tank, and NaOH solution is added to adjust the pH to 8.5. The pore size of the ultrafiltration membrane is 0.05-0.2μm. After the iron sludge is intercepted by the membrane module, it returns to the bottom of the Fenton reactor with the reflux liquid to continue the catalytic reaction. The effluent from the membrane tank is discharged through the product water pump and enters the effluent tank for discharge or reuse after meeting the standards.

[0100] Specifically, after the above treatment steps, the effluent COD is 78 mg / L, the effluent ammonia nitrogen is 4.6 mg / L, the total nitrogen is 28.4 mg / L, and the antimony concentration is 0.13 mg / L, which meets the discharge standards.

[0101]

Example 6

[0102] Wastewater was treated using the wastewater treatment device described in Example 1. The wastewater was depolymerization wastewater from recycled polyester, with a pH of 8.8, COD of 780,000 mg / L, TN of 790 mg / L, ammonia nitrogen of 730 mg / L, and antimony concentration of 8.8 mg / L. The reactor process parameters were as follows:

[0103] (1) Wastewater from the depolymerization of recycled polyester is sent to a homogenization tank for water quality adjustment. The concentration of urea (as N) is 100 mg / L, the concentration of potassium dihydrogen phosphate (as P) is 5 mg / L, and the hydraulic retention time is 3 h.

[0104] (2) The homogenized wastewater is sent to an anaerobic reactor to effectively remove organic matter from the wastewater. The sludge inoculated in the anaerobic reactor is anaerobic granular sludge. The temperature in the anaerobic reactor is 35℃, the hydraulic retention time is 24h, and the COD volumetric loading rate is 20kg / m³. 3 The methane produced can be recycled.

[0105] (3) The effluent from the anaerobic reactor is sent to the MBR reactor, which is equipped with a microfiltration membrane with a pore size of 0.1-0.5 μm for mud-water separation. The modified polyurethane packing is added at a ratio of 25% by volume, with a specific surface area of ​​30,000 m². 2 / m 3 The polyurethane filler was first surface-oxidized with potassium permanganate solution to increase its roughness. After oxidation, 55g of the polyurethane filler and 9g of biomass activated carbon powder were immersed in a cationic water treatment agent (the preparation method of the cationic water treatment agent is the same as in Example 2) and dispersed evenly under ultrasonic conditions for 60 minutes, followed by drying at a constant temperature of 95°C. The dried polyurethane filler was then stirred and impregnated in a modified coating agent for 60 minutes, and cured in a constant temperature oven at 115°C. The modified coating agent, by weight (100 parts), contained 9.5 parts carboxylated chitosan, 9 parts low-density polyolefin microparticles, 0.9 parts sodium carboxymethyl cellulose, 9 parts acrylic acid, 0.9 parts silicone wetting agent, and 70.7 parts tap water.

[0106] (4) The effluent from the MBR reactor is sent to the pH adjustment tank to adjust the pH to 4.1. The iron salt concentration is controlled at 350 mg (Fe) per liter of wastewater, and the amount of H2O2 is added at 5.5 g per liter of wastewater. The hydraulic retention time of the Fenton reactor is 1.5 h.

[0107] (5) The effluent from the Fenton reactor enters the membrane tank, and NaOH solution is added to adjust the pH to 8.8. The pore size of the ultrafiltration membrane is 0.05-0.2μm. After the iron sludge is intercepted by the membrane module, it returns to the bottom of the Fenton reactor with the reflux liquid to continue the catalytic reaction. The effluent from the membrane tank is discharged through the product water pump and enters the effluent tank for discharge or reuse after meeting the standards.

[0108] Specifically, after the above treatment steps, the effluent COD is 76 mg / L, the effluent ammonia nitrogen is 4.7 mg / L, the total nitrogen is 28.9 mg / L, and the antimony concentration is 0.03 mg / L, which meets the discharge standards.

[0109] Comparative Example 1

[0110] The wastewater from the depolymerization process of polyester regeneration had a pH of 8.2, COD of 8300 mg / L, TN of 450 mg / L, ammonia nitrogen of 330 mg / L, and antimony concentration of 3.3 mg / L. It was treated using the same apparatus as in Example 1, but the MBR reactor used unmodified polyurethane packing.

[0111] Specifically, after the above treatment steps, the effluent COD is 150 mg / L, the effluent ammonia nitrogen is 25 mg / L, the total nitrogen is 50 mg / L, and the antimony concentration is 0.5 mg / L.

[0112] Comparative Example 2

[0113] The wastewater from the depolymerization process of the recycled polyester had a pH of 8.2, COD of 8300 mg / L, TN of 450 mg / L, ammonia nitrogen of 330 mg / L, and antimony concentration of 3.3 mg / L. It was treated using the same process as in Example 1, but without membrane modules in the membrane tank, the effluent could not be separated from the cement water, resulting in a significant increase in the subsequent consumption of Fenton oxidation oxidant.

[0114] Comparative Example 3

[0115] The wastewater from the depolymerization and regeneration of waste polyester had a pH of 8.2, COD of 8300 mg / L, TN of 450 mg / L, ammonia nitrogen of 330 mg / L, and antimony concentration of 3.3 mg / L. It was treated using the same apparatus as in Example 1, but without iron sludge recirculation, resulting in a 30% increase in iron salt consumption.

[0116] Comparative Example 4

[0117] The wastewater from the depolymerization of recycled polyester had a pH of 8.2, COD of 8300 mg / L, TN of 450 mg / L, ammonia nitrogen of 330 mg / L, and antimony concentration of 3.3 mg / L. It was treated using the same apparatus as in Example 1, but instead of a membrane tank after the Fenton reactor, it was treated as a conventional settling tank. Therefore, iron salts could not be effectively recycled, and antimony discharge could not meet standards, making the effluent unusable.

[0118] The above description is merely a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, based on the technical teachings provided by the present invention and as common knowledge in the field, other equivalent modifications and improvements can be made, and these should also be considered within the scope of protection of the present invention.

Claims

1. A wastewater treatment device for a tail gas scrubbing tower in the recycling process of waste polyester textiles, comprising a homogenization tank, an anaerobic reactor, an MBR reactor, a pH adjustment tank, a Fenton reactor, a membrane tank, and an effluent tank connected sequentially by pipelines, wherein, The homogenization tank is used for homogenization and mixing with nutrients; The anaerobic reactor is used to carry out anaerobic reactions to remove organic matter from wastewater and decompose recalcitrant organic matter into small molecule organic matter. The MBR reactor is used for biochemical reactions to remove organic matter and total nitrogen from wastewater. Modified polyurethane packing is added to the reaction zone of the MBR reactor; the packing surface is aerobic, while the interior is oxygen-deficient. The preparation method of the modified polyurethane packing includes: surface oxidation treatment of the polyurethane packing with an oxidant; uniform dispersion of the oxidized polyurethane packing, biomass activated carbon powder, and cationic water treatment agent under ultrasonic conditions for 30-60 minutes, followed by drying at a constant temperature of 90-110℃; stirring and impregnation of the dried polyurethane packing in a modified coating agent for 30-60 minutes, followed by curing in a constant temperature oven at 105-120℃; and preparation of the cationic water treatment agent using triethylamine as solvent, pyridine as catalyst, and epichlorohydrin as etherifying agent. The modified coating agent includes carboxylated chitosan, sodium carboxymethyl cellulose, acrylic acid, organosilicon wetting agent, water, and low-density polyolefin microparticles. The pH adjustment tank is used to adjust the pH value; The effluent from the pH adjustment tank is mixed with iron salt and enters the Fenton reactor. The return water from the membrane tank is mixed with H2O2 and then enters the Fenton reactor. The Fenton reactor is used to carry out the Fenton catalytic oxidation reaction. The effluent from the Fenton reactor enters the membrane tank. Alkali solution is added to the membrane tank under aeration conditions. Iron sludge is trapped by the membrane module and returned to the Fenton reactor with the return water from the membrane tank. The effluent from the membrane tank enters the effluent tank.

2. The apparatus according to claim 1, characterized in that, The oxidant is potassium permanganate, concentrated sulfuric acid, or concentrated nitric acid.

3. The apparatus according to claim 1, characterized in that, The modified coating agent comprises the following components in 100 parts by weight: 5-10 parts by weight of carboxylated chitosan, 1-10 parts by weight of low-density polyolefin microparticles, 0.2-1 parts by weight of sodium carboxymethyl cellulose, 1-10 parts by weight of acrylic acid, 0.2-1 parts by weight of organosilicon wetting agent, and 68-93.6 parts by weight of tap water.

4. The apparatus according to any one of claims 1-3, characterized in that, The sludge inoculated in the anaerobic reactor is anaerobic granular sludge.

5. The apparatus according to any one of claims 1-3, characterized in that, The modified polyurethane filler has a specific surface area of ​​20,000-30,000 m². 2 / m 3 ; and / or a microfiltration membrane with a pore size of 0.1-0.5 μm is provided in the MBR reactor.

6. The apparatus according to any one of claims 1-3, characterized in that, The catalyst in the Fenton reactor is an iron salt; and / or, the alkali solution in the alkali tank is introduced into the membrane tank by an alkali metering pump for pH adjustment; and / or, the membrane module is an ultrafiltration membrane with a pore size of 0.05-0.2 μm.

7. The apparatus according to any one of claims 1-3, characterized in that, The wastewater treatment device is used to treat wastewater from the waste polyester regeneration and depolymerization process, wherein the wastewater has a pH of 7-9, a COD of 50,000-800,000 mg / L, a TN of 100-800 mg / L, an ammonia nitrogen of 100-800 mg / L, and an antimony concentration of 1-10 mg / L.

8. A treatment process for a wastewater treatment device for a tail gas scrubbing tower in the waste polyester textile recycling process according to any one of claims 1-7, comprising: Wastewater is sequentially passed through a homogenization tank, an anaerobic reactor, an MBR reactor, a pH adjustment tank, a Fenton reactor, a membrane tank, and an effluent tank. In the homogenization tank, homogenization and mixing with nutrients are performed. In the anaerobic reactor, an anaerobic reaction occurs to remove organic matter from the wastewater and decompose recalcitrant organic matter into smaller molecules. In the MBR reactor, a biochemical reaction to remove organic matter and total nitrogen occurs, removing both organic matter and total nitrogen from the wastewater. The pH is adjusted in the pH adjustment tank. The effluent from the pH adjustment tank is mixed with iron salts and enters the Fenton reactor. The return water from the membrane tank is mixed with H2O2 and then enters the Fenton reactor, where a Fenton catalytic oxidation reaction occurs. The effluent from the Fenton reactor enters the membrane tank. In the membrane tank, alkaline solution is added under aeration conditions. Iron sludge is retained by the membrane modules and returned to the Fenton reactor with the return water from the membrane tank. The effluent from the membrane tank enters the effluent tank. Modified polyurethane packing material is added to the reaction zone of the MBR reactor. The surface of the packing material is aerobic, while the interior is oxygen-deficient.

9. The processing technology according to claim 8, characterized in that, The modified coating agent comprises the following components in 100 parts by weight: 5-10 parts by weight of carboxylated chitosan, 1-10 parts by weight of low-density polyolefin microparticles, 0.2-1 parts by weight of sodium carboxymethyl cellulose, 1-10 parts by weight of acrylic acid, 0.2-1 parts by weight of organosilicon wetting agent, and 68-93.6 parts by weight of tap water.

10. The processing method according to claim 8, characterized in that, In the homogenization tank, adjust the pH to 7-8 and add N nutrients and / or P nutrients.

11. The processing method according to claim 10, characterized in that, The nitrogen nutrient is urea; the amount added is 90-100 mg / L based on nitrogen; and / or the phosphorus nutrient is potassium dihydrogen phosphate; the amount added is 3-5 mg / L based on phosphorus; and / or the hydraulic retention time in the homogenizing tank is 1-5 h.

12. The processing method according to any one of claims 8-11, characterized in that, The COD volumetric loading rate in the anaerobic reactor is 2-20 kg / m³. 3 •d.

13. The processing method according to any one of claims 8-11, characterized in that, In the anaerobic reactor, the hydraulic retention time is 10-25 h; and / or, the temperature of the anaerobic reactor is 20-35 °C.

14. The processing method according to any one of claims 8-11, characterized in that, The modified polyurethane filler is added at a ratio of 10-30% by volume.

15. The processing method according to any one of claims 8-11, characterized in that, In the pH adjustment tank, adjust the pH to 2-4.

5.

16. The processing method according to claim 15, characterized in that, The acid used to adjust the pH is H2SO4.

17. The processing method according to any one of claims 8-11, characterized in that, The H2O2 concentration is 25-30% by weight; and / or, the amount of H2O2 added is 0.5-6g per liter of wastewater.

18. The processing method according to any one of claims 8-11, characterized in that, The iron salt concentration in the Fenton reactor, expressed as iron, is controlled at 40-400 mg per liter of wastewater.

19. The processing method according to claim 18, characterized in that, The iron salt is FeSO4; and / or, the hydraulic retention time of the Fenton reactor is 0.5-2 h.

20. The processing method according to any one of claims 8-11, characterized in that, The wastewater treatment process is used to treat wastewater from the depolymerization process of waste polyester regeneration, wherein the wastewater has a pH of 7-9, a COD of 50,000-800,000 mg / L, a TN of 100-800 mg / L, an ammonia nitrogen of 100-800 mg / L, and an antimony concentration of 1-10 mg / L.

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