Acrylic fiber wastewater treatment process combining biological adsorption-Fe / C micro-electrolysis coupling anaerobic digestion
Through the combined bioadsorption-Fe/C microelectrolytic coupling anaerobic digestion process, the mixture of acrylic wastewater and glycol wastewater is treated, and the problems of high toxicity and poor biochemical properties of acrylic wastewater are solved, efficient removal and resource utilization are achieved, and treatment costs are reduced. It is suitable for water treatment needs under the background of "dual carbon".
Patent Information
- Application Number
- CN202311415498.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-30
- Publication Date
- 2025-05-02
AI Technical Summary
Acrylic wastewater is highly toxic, poor biochemical properties and many suspended oligomers. It is difficult to efficiently treat existing biological treatment processes, and some treatment methods have secondary pollution and high cost problems.
Using a combined biosorption-Fe/C microelectrolytic coupled anaerobic digestion process, the acrylic wastewater is mixed with ethylene glycol wastewater, adjusted the pH and entered the Fe/C microelectrolytic anaerobic fluidized bed for treatment, combined with the aerobic biochemical system, the efficient treatment of acrylic wastewater is finally achieved.
Effectively remove highly toxic substances and difficult-to-degrade oligomers in acrylic wastewater, improve the biochemical properties of wastewater, achieve a polyacrylonitrile removal rate of more than 90%, reduce treatment costs, and meet the low-carbon and low-consumption requirements under the background of "dual carbon".
Abstract
Description
Technical Field
[0001] The invention relates to an acrylic wastewater treatment process combining biological adsorption-Fe / C micro-electrolysis coupled with anaerobic digestion, and belongs to the field of water treatment science and technology. Background Art
[0002] Acrylic fiber, as a textile fiber that is sun-resistant, wear-resistant, insect-resistant, warm, and has a good feel, is widely used in clothing, toys, decoration, and industry, and is highly favored. In 2018, the world's acrylic fiber production reached 1,342kt / year. With the continuous development of emerging downstream industries of acrylic fibers such as carbon fiber, the demand for acrylic fibers will continue to increase in the future.
[0003] However, while acrylic fiber meets the needs of textile production, it also brings a series of environmental pollution problems. For example, acrylic fiber is spun from polyacrylonitrile-based precursors. During its production process, a large amount of highly toxic wastewater will be generated. If it is not properly treated, it will inevitably cause harm to the environment. Common acrylic wastewater has the following characteristics:
[0004] 1. Poor biodegradability: The B / C ratio of acrylic wastewater is usually between 0.1-0.2, which is difficult to biodegrade;
[0005] 2. High toxicity of wastewater: Acrylic wastewater contains more than 100 kinds of complex pollutants, including organic substances such as aldehydes, phenols and nitriles. Most of these organic substances are highly toxic substances, especially the main pollutant acrylonitrile, which has acute neurotoxicity, mutagenicity, carcinogenicity and teratogenicity. As early as 1979, it was set as a priority controlled pollutant by the United States Environmental Protection Agency (USEPA);
[0006] 3. There are many suspended pollutants and short-chain polymer pollutants: Due to the light texture of acrylic fiber, some unfilamented short-chain polymers and suspended matter are brought into acrylic wastewater. They are difficult to settle during the biological treatment process and are easy to wrap around fillers and sludge, resulting in a decrease in treatment effect.
[0007] At present, the main methods for treating acrylic wastewater include physical and chemical methods, biochemical methods, and chemical methods. Among them, the biochemical method is the most widely used wastewater treatment technology. However, due to its characteristics of difficult biodegradation, high concentration, and high toxicity, it is difficult for biological treatment processes to efficiently treat acrylic wastewater. Some companies use other physical and chemical methods, which temporarily alleviate the pressure of subsequent biochemical treatment, but often cause secondary pollution or face high treatment costs. Therefore, it is necessary to develop an efficient, economical, low-carbon and low-consumption comprehensive treatment process for acrylic wastewater. Summary of the invention
[0008] The purpose of the present invention is to solve the deficiencies in the prior art, introduce ethylene glycol wastewater into acrylic wastewater, and combine biological adsorption-Fe / C micro-electrolysis coupled anaerobic digestion to effectively deal with the difficult problems of acrylic wastewater with high suspended oligomers, high toxicity and poor biodegradability, while realizing comprehensive treatment of the two wastewaters and achieving standard discharge.
[0009] The invention relates to a process for treating acrylic wastewater by combining biological adsorption-Fe / C micro-electrolysis coupled with anaerobic digestion, which solves the problems of high oligomer content, high toxicity and poor biodegradability of acrylic wastewater. The process can be widely used in wastewater treatment and belongs to the field of water treatment science and technology.
[0010] To achieve the purpose of the present invention, the present invention provides a process for treating acrylic fiber wastewater by combining biological adsorption-Fe / C micro-electrolysis coupled with anaerobic digestion, comprising the following treatment steps:
[0011] (1): Discharge the acrylic fiber wastewater into the regulating tank I and adjust the pH to acidic, preferably to pH=3;
[0012] (2): discharging the acidic acrylic wastewater into a sequencing batch reactor, and mixing and adsorbing the wastewater with the sludge in the sequencing batch reactor;
[0013] (3): The acrylic wastewater treated in step (2) is discharged into regulating tank II, mixed with ethylene glycol wastewater and adjusted to a neutral pH, and then sent to a Fe / C micro-electrolysis anaerobic fluidized bed for degradation. The effluent of the Fe / C micro-electrolysis anaerobic fluidized bed is sent to an aerobic biochemical system for biological treatment, and discharged after precipitation in a secondary sedimentation tank. The acrylic wastewater in step (1) is produced by a one-step wet process of sodium thiocyanate, including but not limited to polymerization, spinning, solvent recovery and other processes.
[0014] In the step (2), the sludge dosage is 15 g / L-45 g / L, the adsorption is carried out at room temperature (25° C.), the adsorption time is 30-60 min, and the stirring rate is 100 rpm-500 rpm.
[0015] In the step (3), the mixing ratio of ethylene glycol wastewater to acrylic fiber wastewater is 1:1, and the pH is adjusted between 7.0 and 8.0; the Fe / C micro-electrolysis anaerobic fluidized bed is inoculated with anaerobic granular sludge, and the dosage of the anaerobic granular sludge is 2-3 VSS g / L (VSS, Volatile Suspended Solids).
[0016] The Fe / C micro-electrolysis anaerobic fluidized bed in step (3) uses waste iron slag and activated carbon as fillers, with a particle size of 150-300 mesh and a concentration of 0.1-0.3 kg / m 3 .
[0017] The inlet and outlet mode of the Fe / C micro-electrolysis anaerobic fluidized bed in step (3) is bottom-in and top-out, the rising flow rate is 1.0-1.2 m / h, and a 50-mesh wire mesh is arranged at the outlet weir to prevent particle loss; the hydraulic retention time of the anaerobic biological treatment is at least 24 hours, and the hydraulic retention time can be extended by circulating the outlet water and connecting multiple reactors in series.
[0018] The filler is placed in a Fe / C micro-electrolysis anaerobic fluidized bed. By controlling the rising flow rate of the anaerobic fluidized bed and the flow rate of the upper effluent weir, the retention and fluidization uniformity of the filler in the anaerobic reactor are achieved. The Fe / C micro-electrolysis principle is used to crack the unadsorbed oligomers in the wastewater to improve the biodegradability of the wastewater.
[0019] The hydraulic retention time of the aerobic biochemical system in step (3) is at least 12 hours.
[0020] The present invention adopts a reasonable distribution and confluence mechanism for acrylic wastewater that is difficult to degrade and highly toxic. The acrylic wastewater containing polymers is adsorbed and mixed with ethylene glycol wastewater to enter the Fe / C micro-electrolysis anaerobic fluidized bed for treatment. The sludge after adsorption can be dehydrated and used as fuel, solving the problem of difficult degradation of polymers and energy recovery. The ethylene glycol wastewater in the petrochemical processing technology has strong biodegradability, and this type of wastewater can be used to adjust the biodegradability of the Fe / C micro-electrolysis anaerobic fluidized bed, avoiding the inability of sludge to maintain a sufficiently high concentration due to too low organic substrate, which affects the effluent water quality.
[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0022] (1) The present invention achieves efficient treatment of acrylic wastewater, solving the difficult problem of high toxicity and poor biodegradability of acrylic wastewater.
[0023] (2) The present invention realizes the recycling of excess sludge at a low cost, and can remove more than 90% of pollutants such as polyacrylonitrile after adsorption-anaerobic biological treatment.
[0024] (3) The present invention does not need to change the original sewage treatment method, but can transform the treatment process of the sewage treatment plant at a low cost, significantly reduce the difficulty of existing sewage system treatment, enhance the efficiency of microbial wastewater treatment, and achieve standard discharge of acrylic wastewater.
[0025] The process is simple to operate, has low energy consumption, and produces little sludge, which meets the requirements for the treatment of highly toxic and high-concentration wastewater under the background of "dual carbon". It not only has good treatment capacity for one-step wet acrylic wastewater, but also can utilize the remaining sludge to achieve "waste treatment with waste", and realize the comprehensive treatment of two wastewaters at the same time. The combined biological adsorption-Fe / C micro-electrolysis coupled anaerobic digestion treatment method strengthens anaerobic biological treatment by adding waste iron slag and activated carbon, and strengthens the direct electron transfer between pollutants and microbial colonies. In addition to having a certain removal capacity for acrylic wastewater, it also has a certain effect on wastewater with similar high COD, high toxicity, and high molecular weight polymers as acrylic wastewater. It has potential wide application value and broad application prospects in the field of water treatment. DETAILED DESCRIPTION
[0026] In order to make the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are clearly and completely described with preferred embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0027] The acrylic fiber wastewater treatment system in the embodiment of the present invention includes a sequencing batch reactor, a Fe / C micro-electrolysis anaerobic fluidized bed and an aerobic biochemical system.
[0028] Sequencing batch reactor: In the sequencing batch reactor, sludge microorganisms rapidly multiply in the aerobic environment created by the aeration of the system, and consume and degrade organic matter, ammonia, nitrogen and other pollutants in the acrylic fiber wastewater. The above-mentioned consumption and degradation process is called the mixed adsorption of wastewater and sludge. After the mixed adsorption, it enters the precipitation stage, and the sludge settles to the bottom of the sequencing batch reactor, and the treated effluent is discharged to the regulating tank II. The sludge dosage is 15g / L-45g / L, the adsorption is carried out at room temperature (25°C), the adsorption time is 30-60min, and the stirring rate is 100rpm-500rpm. The adsorbed sludge is desorbed and regenerated by slow stirring, and the regeneration time is 5h. The regenerated sludge can be converted into fuel through dehydration to realize resource utilization, and the liquid produced by sludge dehydration is passed into the anaerobic system for anaerobic digestion. Specifically, the above-mentioned sludge is taken from the residual sludge in the second sedimentation tank of the sewage treatment plant. Fe / C micro-electrolysis anaerobic fluidized bed: Fe / C micro-electrolysis anaerobic fluidized bed has the function of Fe / C micro-electrolysis coupled with anaerobic digestion, with waste iron slag and activated carbon as fillers, the particle size is 150-300 mesh, and the concentration is 0.1-0.3kg / m 3; The inlet and outlet mode of the Fe / C micro-electrolysis anaerobic fluidized bed is bottom-in-top-out, with an ascending flow rate of 1.0-1.2 m / h. A 50-mesh wire mesh is arranged at the outlet weir to prevent the loss of particles. By controlling the ascending flow rate of the anaerobic fluidized bed and the upper outlet weir flow rate, the retention and fluidization uniformity of the filler in the fluidized bed are achieved; at the same time, the Fe / C micro-electrolysis anaerobic fluidized bed is inoculated with anaerobic granular sludge, and the dosage of the anaerobic granular sludge is 2-3 g / L. During the use of the fluidized bed, the granular sludge is in a suspended state due to the ascending flow rate. The hydraulic retention time of anaerobic biological treatment is not less than 24 hours, and the hydraulic retention time can be extended by effluent circulation and multiple reactors in series. The Fe / C micro-electrolysis anaerobic fluidized bed uses the Fe / C micro-electrolysis principle to crack the unadsorbed oligomers in the wastewater and improve the biodegradability of the wastewater; at the same time, the granular sludge rich in anaerobic bacteria is used to remove COD and difficult-to-degrade organic pollutants.
[0029] Aerobic biochemical system: Through the participation of aerobic bacteria, COD, ammonia nitrogen and total phosphorus in wastewater can be greatly removed.
[0030] Example 1
[0031] The treatment target is the one-step wet acrylic wastewater from a certain acrylic fiber factory. The untreated one-step wet acrylic wastewater from the factory has a COD of 507.136 mg / L, an acrylonitrile concentration of 50 mg / L, and SCN - The concentration is 99.51 mg / L, the Mw is 1180 g / mol, and the Mn is 926 g / mol.
[0032] The acrylic wastewater is first discharged into the regulating tank I and adjusted to pH=3, and then the acrylic wastewater adjusted to acidity is discharged into the sequencing batch reactor for biosorption.
[0033] The biological adsorption conditions were as follows: sludge dosage was 15 g / L, adsorption was carried out at room temperature (25°C), adsorption time was 30 min, stirring speed was 250 rpm. The COD removal rate was 60%, and the polyacrylonitrile removal rate was 60%.
[0034] The acrylic wastewater after the above biological adsorption is discharged into the regulating tank II, mixed with the ethylene glycol wastewater produced from the petrochemical processing technology in a 1:1 ratio, and the pH is adjusted to 7.0-8.0. Then it is sent to the Fe / C micro-electrolysis anaerobic fluidized bed. After 24 hours of anaerobic digestion, the COD removal rate is 75%, the effluent acrylonitrile concentration is 3 mg / L, and the effluent SCN - The concentration was 9 mg / L and the removal rate of polyacrylonitrile was 96%.
[0035] The hydraulic retention time of the aerobic biochemical system is 24 hours. After sedimentation in the secondary sedimentation tank, the effluent can meet the discharge standards.
[0036] The above-mentioned ethylene glycol wastewater produced from the petrochemical process has a COD of 1030 mg / L, an NH3 concentration of 120 mg / L, and a SS - The concentration is 170mg / L.
[0037] Example 2
[0038] The treatment target is the one-step wet acrylic wastewater from a certain acrylic fiber factory. The untreated one-step wet acrylic wastewater from the factory has a COD of 209.12 mg / L, an acrylonitrile concentration of 50 mg / L, and SCN - The concentration is 12.8659 mg / L, the Mw is 976 g / mol, and the Mn is 872 g / mol.
[0039] The acrylic wastewater is first discharged into the regulating tank I and adjusted to pH=3, and then the acrylic wastewater adjusted to acidity is discharged into the sequencing batch reactor for biosorption.
[0040] The biological adsorption conditions were as follows: the sludge dosage was 45 g / L, the adsorption was carried out at room temperature (25°C), the adsorption time was 30 min, and the stirring rate was 500 rpm. The COD removal rate was 70%, and the polyacrylonitrile removal rate was 60%.
[0041] The acrylic wastewater after the above biological adsorption was discharged into the regulating tank II, mixed with the ethylene glycol wastewater produced from the petrochemical processing technology in a 1:1 ratio, and the pH was adjusted to 7.0-8.0. Then it was sent to the Fe / C micro-electrolysis anaerobic fluidized bed. After anaerobic digestion for 24 hours, the COD removal rate was 78%, the effluent acrylonitrile concentration was 4 mg / L, and the effluent SCN - The concentration was 8 mg / L and the removal rate of polyacrylonitrile was 97%.
[0042] The hydraulic retention time of the aerobic biochemical system is 12 hours. After sedimentation in the secondary sedimentation tank, the effluent can meet the discharge standards.
[0043] The above-mentioned ethylene glycol wastewater produced from the petrochemical process has a COD of 1030 mg / L, an NH3 concentration of 120 mg / L, and a SS - The concentration is 170mg / L.
[0044] Example 3
[0045] The treatment target is the one-step wet acrylic wastewater from a certain acrylic fiber factory. The untreated one-step wet acrylic wastewater from the factory has a COD of 615.104 mg / L, an acrylonitrile concentration of 50 mg / L, and SCN - The concentration is between 0-100 mg / L, the Mw is 1395 g / mol, and the Mn is 1216 g / mol.
[0046] The acrylic wastewater is first discharged into the regulating tank I and adjusted to pH=3, and then the acrylic wastewater adjusted to acidity is discharged into the sequencing batch reactor for biosorption.
[0047] The biological adsorption conditions were as follows: the sludge dosage was 15 g / L, the adsorption was carried out at room temperature (25°C), the adsorption time was 60 min, and the stirring rate was 100 rpm. The COD removal rate was 62%, and the polyacrylonitrile removal rate was 63%.
[0048] The acrylic wastewater after the above biological adsorption was discharged into the regulating tank II, mixed with the ethylene glycol wastewater from the petrochemical processing technology in a 1:1 ratio, and the pH was adjusted to 7.0-8.0. Then it was sent to the Fe / C micro-electrolysis anaerobic fluidized bed. After 24 hours of anaerobic digestion, the COD removal rate was 72%, the effluent acrylonitrile concentration was 2 mg / L, and the effluent SCN - The concentration was 5 mg / L and the removal rate of polyacrylonitrile was 98%.
[0049] The hydraulic retention time of the aerobic biochemical system is 24 hours. After sedimentation in the secondary sedimentation tank, the effluent can meet the discharge standards.
[0050] The above-mentioned ethylene glycol wastewater produced from the petrochemical process has a COD of 1030 mg / L, an NH3 concentration of 120 mg / L, and a SS - The concentration is 170mg / L.
Claims
1. A process for treating acrylic fiber wastewater by combining biological adsorption-Fe / C micro-electrolysis coupled with anaerobic digestion, comprising the following treatment steps: (1): Discharge the acrylic fiber wastewater into regulating tank I and adjust the pH to acidic; (2): discharging the acidic acrylic wastewater into a sequencing batch reactor, and mixing and adsorbing the wastewater with the sludge in the sequencing batch reactor; (3): The acrylic fiber wastewater treated in step (2) is discharged into regulating tank II, mixed with ethylene glycol wastewater and adjusted to a neutral pH, and then sent to a Fe / C micro-electrolysis anaerobic fluidized bed for degradation. The effluent from the Fe / C micro-electrolysis anaerobic fluidized bed is sent to an aerobic biochemical system for biological treatment and discharged after sedimentation in a secondary sedimentation tank.
2. The wastewater treatment process according to claim 1, characterized in that: In the step (1), the pH is adjusted to 3; in the step (2), the sludge dosage is 15 g / L-45 g / L, the adsorption is carried out at room temperature (25° C.), the adsorption time is 30-60 min, and the stirring rate is 100 rpm-500 rpm.
3. The wastewater treatment process according to claim 2, characterized in that: In the step (3), the mixing ratio of ethylene glycol wastewater to acrylic fiber wastewater is 1:1, and the pH is adjusted between 7.0 and 8.0; the Fe / C micro-electrolysis anaerobic fluidized bed is inoculated with anaerobic granular sludge, and the dosage of the anaerobic granular sludge is 2-3 g / L.
4. The wastewater treatment process according to claim 3, characterized in that: The Fe / C micro-electrolysis anaerobic fluidized bed in step (3) uses waste iron slag and activated carbon as fillers, with a particle size of 150-300 mesh and a concentration of 0.1-0.3 kg / m 3 .
5. The wastewater treatment process according to claim 4, characterized in that: The inlet and outlet mode of the Fe / C micro-electrolysis anaerobic fluidized bed in step (3) is bottom-in and top-out, the rising flow rate is 1.0-1.2 m / h, and a 50-mesh wire mesh is arranged at the outlet weir; the hydraulic retention time of the anaerobic biological treatment is at least 24 hours.
6. The wastewater treatment process according to claim 5, characterized in that: The hydraulic retention time of the aerobic biochemical system in step (3) is at least 12 hours.