Wastewater treatment process for butadiene extraction

Abstract

The invention relates to the technical field of environmental protection, in particular to a wastewater treatment process for butadiene extraction. According to the wastewater treatment process disclosed by the invention, the biodegradability of the wastewater is improved by adopting ultrasonic-microelectrolysis combined pretreatment, and various pollutants in the wastewater are efficiently removed through a series of innovative means such as synergistic biological treatment, a novel sulfide treatment method, an optimized advanced oxidation process and integration of membrane separation and concentration technologies. The treated wastewater is discharged after reaching the standard, the water resource recovery rate is remarkably improved, meanwhile, the treatment cost is reduced, and good economic and environmental benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a wastewater treatment process for butadiene extraction. Background Art

[0002] As an important organic chemical raw material, butadiene is widely used in the fields of synthetic rubber, resin, etc. A large amount of wastewater is generated in the process of butadiene extraction. These wastewaters are complex in composition and contain a variety of pollutants such as butadiene, vinyl acetylene, ethyl acetylene, aromatic hydrocarbons, sulfides, phenols and nitrous acid. If they are directly discharged without effective treatment, they will cause serious pollution to the environment. However, there are many problems with the existing butadiene extraction wastewater treatment process. The traditional process has a poor removal effect on organic matter in butadiene extraction wastewater, especially some difficult-to-degrade organic matter. For example, the removal rate of aromatic hydrocarbons and difficult-to-degrade high-molecular organic compounds is low, resulting in the chemical oxygen demand (COD) in the treated wastewater still exceeding the standard and difficult to meet the discharge standard. The sulfide in the wastewater is highly corrosive and toxic. Traditional treatment methods such as simple precipitation or oxidation methods are difficult to completely remove the sulfide, and secondary pollution is easily generated during the treatment process, such as the generation of hydrogen sulfide gas that escapes into the air. Existing treatment processes often consume a large amount of chemicals and energy. For example, a large amount of oxidants are used in advanced oxidation processes, which not only increases the treatment cost, but also the excessive chemical residues may cause new harm to the environment. Some treatment processes require multiple treatment units to be connected in series, the operation process is cumbersome, and the equipment occupies a large area. This not only increases the construction cost, but also makes maintenance and management difficult in actual operation, and is prone to failure, affecting the stability of the treatment effect. After the butadiene extraction wastewater is treated, the proportion of recyclable water resources is low, and most of the treated water can only be discharged, resulting in a waste of water resources and not meeting the requirements of sustainable development. It is urgent to solve the many problems existing in the existing process, such as poor organic matter removal effect, difficult sulfide treatment, high cost, cumbersome process and low water resource recovery rate. Summary of the invention

[0003] The invention provides a wastewater treatment process for butadiene extraction, comprising the following steps: introducing butadiene extraction wastewater into an ultrasound-micro-electrolysis reactor for pretreatment, wherein the ultrasound frequency is 20-40kHz, the power is 300-500W, the micro-electrolysis electrode adopts an iron-carbon electrode, and the reaction time is 30-60 minutes; after the reaction is completed, a flocculant is added for flocculation precipitation, wherein the flocculant is polyacrylamide, and the addition amount is 5-10 mg / L.

[0004] Furthermore, the pretreated wastewater enters the anaerobic bioreactor for treatment, and the temperature in the anaerobic reactor is controlled to be 35-38° C., the pH value is 6.8-7.2, and the hydraulic retention time is 12-24 hours.

[0005] Furthermore, the wastewater after anaerobic treatment enters the aerobic bioreactor, and the aerobic reactor is inoculated with a domesticated composite microbial flora including:

[0006] Bacillus

[0007] Bacillus subtilis: 30%. The proteases and lipases it secretes can quickly decompose protein and fat macromolecules in wastewater and convert them into small molecules that can be easily used by other microorganisms, such as amino acids and fatty acids, thus reducing the burden on subsequent treatment links.

[0008] Bacillus licheniformis: 20%. It has a unique ability to degrade phenolic substances. Through its own metabolic pathway, it gradually oxidizes phenols in wastewater and eventually converts them into harmless carbon dioxide and water, significantly reducing the content of phenolic pollutants and improving the biodegradability of wastewater.

[0009] Pseudomonas

[0010] Pseudomonas aeruginosa: 20%. In an aerobic environment, it can use a variety of carbon and nitrogen sources as nutrients, and has high degradation activity for aromatic compounds in wastewater, such as benzene and toluene. Through a series of complex enzymatic reactions, it gradually converts aromatics into organic acids, and finally decomposes them into carbon dioxide and water.

[0011] Pseudomonas putida: 15%. Under aerobic conditions, it has a high affinity for sulfide and can quickly oxidize sulfide into sulfate, working synergistically with subsequent sulfide treatment units to further reduce the residual sulfide in wastewater and reduce its harm to the environment.

[0012] Nitrifying and denitrifying bacteria

[0013] Nitrite bacteria: account for 5%. The main function is to oxidize ammonia nitrogen in wastewater into nitrite, start the first step of nitrification reaction, and provide substrate for the subsequent action of nitrate bacteria.

[0014] Nitrate bacteria: 5%. Taking over the role of nitrite bacteria, further oxidizing nitrite into nitrate, effectively removing ammonia nitrogen pollutants in wastewater and reducing the risk of eutrophication of water bodies.

[0015] Paracoccus denitrifying: accounts for 5%. In an anaerobic environment, it uses organic matter in wastewater as a carbon source to reduce nitrates to nitrogen gas, achieving complete nitrogen removal and completing the entire denitrification process.

[0016] Control the dissolved oxygen to 2-4 mg / L, the pH to 7.0-7.5, and the hydraulic retention time to 8-12 hours.

[0017] Further, the wastewater after aerobic treatment enters a sulfide treatment unit, ferrous sulfate is added to the wastewater so that the molar ratio of iron ions to sulfides is 1.5-2.0, and iron sulfide precipitation is generated by reaction, and the reaction time is 20-30 minutes; the supernatant after precipitation enters a catalytic oxidation reactor, and a catalytic oxidation system with manganese dioxide as a catalyst is added, and the residual sulfide is oxidized to sulfate at a temperature of 40-50°C and a reaction time of 30-40 minutes.

[0018] Further, the wastewater after sulfide treatment enters a photocatalytic oxidation reactor, with silver-doped titanium dioxide as a photocatalyst, the dosage of the photocatalyst is 0.5-1.0 g / L, and a photocatalytic oxidation reaction is carried out under ultraviolet light, and the reaction time is 60-90 minutes.

[0019] Furthermore, the wastewater after photocatalytic oxidation is filtered and concentrated in turn through an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane, wherein the ultrafiltration membrane has a molecular weight cutoff of 10-50 kDa, the nanofiltration membrane has a molecular weight cutoff of 100-500 Da, and the reverse osmosis membrane has a desalination rate greater than 95%.

[0020] Furthermore, the membrane concentrate is distilled to recover the organic raw material of butadiene; the sludge generated in the wastewater treatment process is first subjected to biological drying treatment at a temperature of 30-35°C and a ventilation volume of 0.2-0.3m 3 / (kg·h), the drying time is 3-5 days, and then a chemical conditioner is added, wherein the chemical conditioner is polyaluminium chloride, and the dosage is 10-15mg / L, and dehydration treatment is carried out to reduce the moisture content of the sludge to below 60%.

[0021] Furthermore, sensors are installed in the pretreatment stage, anaerobic treatment stage, aerobic treatment stage, sulfide treatment stage, photocatalytic oxidation stage, filtration and concentration stage of wastewater treatment, respectively. The sensors include ammonia nitrogen sensors, temperature sensors, pH sensors, and dissolved oxygen sensors for real-time monitoring of water quality indicators, temperature, pH value, and dissolved oxygen parameters. The intelligent control system automatically adjusts the operating parameters of each treatment unit according to the monitoring data, including the flow rate of the pump, the air volume of the fan, and the dosage of the agent.

[0022] Furthermore, the wastewater treatment process treats butadiene extraction wastewater to obtain treated water, wherein the chemical oxygen demand (COD) of the treated water is lower than 50 mg / L, and the sulfide content is lower than the national emission standard.

[0023] Furthermore, the wastewater treatment process treats sludge recovered during butadiene extraction wastewater, wherein the moisture content of the sludge is less than 60%, and after biological drying and chemical conditioning, the volume and weight of the sludge are reduced by 50%-60% compared to before treatment.

[0024] Beneficial technical effects:

[0025] The organic matter removal effect is significant: through the synergistic effect of enhanced pretreatment, coordinated biological treatment and advanced oxidation technologies, the organic matter removal rate in wastewater reaches more than 95%, and the chemical oxygen demand (COD) can be reduced to below 50mg / L, meeting the national emission standards.

[0026] Complete removal of sulfides: By using the method of iron salt-sulfide co-precipitation combined with catalytic oxidation, the removal rate of sulfides reaches more than 99%, effectively avoiding the generation of secondary pollution such as hydrogen sulfide.

[0027] Reduce processing costs: The optimized processing technology reduces the use of chemical agents. At the same time, the intelligent control system achieves energy conservation and emission reduction, reduces energy consumption, and reduces processing costs by 30%-40% compared with traditional processes.

[0028] The constructed double-circulation anaerobic reaction system promotes rapid contact and transformation between substrate and microorganisms in the inner loop, and achieves deep degradation in the outer loop. This innovation greatly improves the degradation rate of aromatic hydrocarbons in the anaerobic treatment stage. When combined with the subsequent aerobic biological treatment step, it provides a more easily handled substrate for the aerobic stage, reduces the burden of aerobic treatment, and improves the overall organic matter removal efficiency. The microbial community construction technology that simulates the natural ecosystem is used to domesticate a composite microbial flora. These floras form a mutually beneficial symbiotic relationship and have the ability to synergistically remove a variety of pollutants under precisely controlled conditions of dissolved oxygen, pH value and hydraulic retention time. In response to the anaerobic biological treatment, the anaerobic treatment initially decomposes macromolecular organic matter, and the aerobic stage uses the composite flora to efficiently degrade the intermediate products and residual small molecular organic matter after anaerobic treatment, especially phenolic substances. The two-step method is used to synergistically treat sulfides. Ultrasonic assisted precipitation technology is introduced in the precipitation stage, and the ultrasonic cavitation effect is used to promote the agglomeration and sedimentation of iron sulfide particles, shorten the precipitation time and improve the efficiency; the catalytic oxidation stage uses a supported manganese dioxide catalyst and performs surface modification to increase the active sites. In line with the water quality conditions after aerobic biological treatment, after aerobic treatment, the sulfide concentration and composition in the wastewater are suitable for this two-step treatment, which improves the sulfide removal rate and effectively avoids secondary pollution, reducing the burden for subsequent advanced oxidation treatment. Titanium dioxide is doped and modified by sol-gel method combined with plasma treatment technology, and the silver doping concentration and distribution are precisely controlled to improve the efficiency of photogenerated carrier separation; and photocatalytic oxidation is coupled with electrochemical oxidation. In combination with the previous sulfide treatment step, after sulfide treatment, the residual refractory organic matter in the wastewater is suitable for this enhanced photocatalytic oxidation treatment, which further oxidizes and decomposes the residual refractory organic matter to ensure that the wastewater COD meets the discharge standards. The front and back steps of this process work together to enable photocatalytic oxidation to play a better role.

[0029] High water resource recovery rate: The integrated application of membrane separation and concentration technology has enabled the water resource recovery rate to reach 70%-80%, realizing the recycling of water resources, reducing the amount of fresh water used, and meeting the requirements of sustainable development.

[0030] Resource recycling: Recovering organic raw materials such as butadiene from wastewater through methods such as distillation not only reduces the emission of pollutants but also creates certain economic benefits.

[0031] Significant sludge reduction: The sludge treatment method that combines biological drying and chemical conditioning reduces the volume and weight of sludge by 50%-60%, reducing the sludge treatment cost and the impact on the environment.

[0032] Green and environmentally friendly: The use of green chemical agents reduces the residue and pollution of chemical agents to the environment, and the entire treatment process meets the requirements of green and environmental protection. DETAILED DESCRIPTION

[0033] Example 1

[0034] Preprocessing:

[0035] 1000L of butadiene extraction wastewater was introduced into the ultrasonic-micro-electrolysis reactor. The ultrasonic frequency was set to 30kHz, the power was set to 400W, the micro-electrolysis electrode was an iron-carbon electrode, and the reaction time was 45 minutes.

[0036] After the reaction, polyacrylamide (PAM) was added to the wastewater at a dosage of 8 mg / L for flocculation and precipitation for 30 minutes to remove suspended solids and some organic matter in the wastewater.

[0037] Biological treatment:

[0038] The pretreated wastewater enters the anaerobic bioreactor, and the temperature in the anaerobic reactor is controlled to be 36°C, the pH value is 7.0, and the hydraulic retention time is 18 hours.

[0039] The wastewater after anaerobic treatment enters the aerobic bioreactor and is inoculated with a domesticated composite microbial flora. The dissolved oxygen is controlled at 3 mg / L, the pH value is 7.2, and the hydraulic retention time is 10 hours.

[0040] Sulfide treatment:

[0041] The wastewater after aerobic treatment enters the sulfide treatment unit, and ferrous sulfate is added to make the molar ratio of iron ion to sulfide 1.8, and the reaction time is 25 minutes.

[0042] The supernatant after precipitation enters the catalytic oxidation reactor, and a catalytic oxidation system with manganese dioxide as a catalyst is added, the temperature is 45° C., and the reaction time is 35 minutes.

[0043] Advanced Oxidation Treatment:

[0044] The wastewater after sulfide treatment enters the photocatalytic oxidation reactor, with silver-doped titanium dioxide as the photocatalyst. The dosage of the photocatalyst is 0.8 g / L, and the reaction takes 75 minutes under ultraviolet light.

[0045] Membrane separation and concentration:

[0046] The wastewater after photocatalytic oxidation is filtered and concentrated by ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane in turn. The molecular weight cutoff of ultrafiltration membrane is 30kDa, the molecular weight cutoff of nanofiltration membrane is 300Da, and the desalination rate of reverse osmosis membrane is 96%.

[0047] The membrane concentrate enters the distillation unit to recover organic raw materials such as butadiene.

[0048] Sludge treatment:

[0049] The sludge generated during the wastewater treatment process is first subjected to biological drying treatment at a temperature of 32°C and a ventilation volume of 0.25m 3 / (kg·h) and the drying time was 4 days.

[0050] Then, polyaluminium chloride (PAC) was added at a dosage of 12 mg / L for dehydration treatment.

[0051] Intelligent Control:

[0052] Sensors are installed in each treatment unit to monitor water quality indicators, temperature, pH value, dissolved oxygen and other parameters in real time.

[0053] The intelligent control system automatically adjusts parameters such as pump flow, fan air volume, and dosage of reagents based on monitoring data.

[0054] Detailed modeling and solving algorithm method:

[0055] Data collection and preprocessing: High-precision sensors are installed in various links of wastewater treatment, such as ultrasound-microelectrolysis reactors, anaerobic bioreactors, aerobic bioreactors, sulfide treatment units, photocatalytic oxidation reactors, and membrane separation and concentration devices, to collect water quality indicators (such as COD, sulfide content, phenolic substance concentration, etc.), temperature, pH value, dissolved oxygen and other parameters in real time. The collected data is first denoised, and the sliding average filter algorithm is used to remove high-frequency noise in the data to ensure data stability. Then, through normalization, the parameters of different dimensions are converted into values ​​in the [0,1] interval to facilitate subsequent data analysis and model training.

[0056] Establish a dynamic model: Use the long short-term memory network (LSTM) in the deep learning algorithm to establish a dynamic model for each treatment unit. Taking the anaerobic bioreactor as an example, the collected temperature, pH value, hydraulic retention time, and influent water quality data are used as input. After training the LSTM network, the complex relationship and time series characteristics between the parameters are learned to establish a dynamic model of organic matter degradation and gas generation during anaerobic treatment. For aerobic bioreactors, the LSTM network is also used, combined with parameters such as dissolved oxygen and microbial flora concentration, to establish a dynamic model of pollutant removal during aerobic treatment. In this way, a dynamic model that can accurately reflect its operating status and treatment effect is established for each treatment unit.

[0057] Optimization control algorithm: The model predictive control (MPC) algorithm is used to optimize the operating parameters of each treatment unit. Taking the flow control of the pump as an example, according to the established dynamic model, the demand and effect of wastewater treatment in the future are predicted, and the optimal pump flow regulation scheme is calculated through the MPC algorithm to make the residence time and flow rate of wastewater in each treatment unit reach the optimal state to improve the treatment efficiency. For the air volume control of the fan, it is also based on the dynamic model and MPC algorithm. According to the dissolved oxygen demand in the aerobic bioreactor, the fan air volume is adjusted in real time to ensure the growth and metabolism of microorganisms in a suitable dissolved oxygen environment. In terms of the control of the dosage of the agent, according to the water quality monitoring data and the dynamic model, the MPC algorithm is used to accurately calculate the optimal dosage of agents such as ferrous sulfate and polyacrylamide, while ensuring the treatment effect, reducing the waste of agents and cost consumption.

[0058] Model update and optimization: As the wastewater treatment process continues, new data is continuously collected, and the established dynamic model is updated and optimized using online learning algorithms. For example, the stochastic gradient descent (SGD) algorithm is used to adjust the weights of the LSTM network in real time based on the newly collected data, so that the model can adapt to changes in wastewater quality and water volume, and always maintain accurate prediction and control capabilities for the treatment process. At the same time, the model is regularly evaluated and verified. By comparing the actual treatment effect with the model prediction results, problems in the model are discovered in a timely manner, and targeted optimization is performed to ensure the stability and reliability of the intelligent control system.

[0059] Example 2

[0060] Pretreatment: Take 1000L of butadiene extraction wastewater and introduce it into the ultrasonic-micro-electrolysis reactor. Set the ultrasonic frequency to 20kHz, the power to 300W, the micro-electrolysis electrode to use an iron-carbon electrode, and the reaction time to 30 minutes. After the reaction, add polyacrylamide (PAM) to the wastewater at a dosage of 5mg / L for flocculation and precipitation for 30 minutes to remove suspended matter and some organic matter in the wastewater.

[0061] Biological treatment: The pretreated wastewater enters the anaerobic bioreactor, and the temperature in the anaerobic reactor is controlled at 35°C, the pH value is 6.8, and the hydraulic retention time is 12 hours. The anaerobic wastewater enters the aerobic bioreactor, inoculated with domesticated composite microbial flora, and the dissolved oxygen is controlled at 2 mg / L, the pH value is 7.0, and the hydraulic retention time is 8 hours.

[0062] Sulfide treatment: The wastewater after aerobic treatment enters the sulfide treatment unit, and ferrous sulfate is added to make the molar ratio of iron ions to sulfide 1.5, and the reaction time is 20 minutes. The supernatant after precipitation enters the catalytic oxidation reactor, and a catalytic oxidation system with manganese dioxide as the catalyst is added, the temperature is 40°C, and the reaction time is 30 minutes.

[0063] Advanced oxidation treatment: The wastewater after sulfide treatment enters the photocatalytic oxidation reactor, with silver-doped titanium dioxide as the photocatalyst. The dosage of the photocatalyst is 0.5g / L, and the reaction takes place under ultraviolet light for 60 minutes.

[0064] Membrane separation and concentration: The wastewater after photocatalytic oxidation is filtered and concentrated through ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane in turn. The molecular weight cutoff of ultrafiltration membrane is 10kDa, the molecular weight cutoff of nanofiltration membrane is 100Da, and the desalination rate of reverse osmosis membrane is 95%. The membrane concentrate enters the distillation device to recover organic raw materials such as butadiene.

[0065] Sludge treatment: The sludge generated during the wastewater treatment process is first subjected to biological drying treatment at a temperature of 30°C and a ventilation volume of 0.2m 3 / (kg·h), the drying time was 3 days. Then polyaluminium chloride (PAC) was added at a dosage of 10 mg / L for dehydration treatment.

[0066] Intelligent control: Install sensors in each processing unit to monitor water quality indicators, temperature, pH value, dissolved oxygen and other parameters in real time. The intelligent control system automatically adjusts the pump flow, fan air volume, dosage of the agent and other parameters according to the monitoring data.

[0067] Example 3

[0068] Pretreatment: Take 1000L of butadiene extraction wastewater and introduce it into the ultrasonic-micro-electrolysis reactor. Set the ultrasonic frequency to 40kHz, the power to 500W, the micro-electrolysis electrode to use an iron-carbon electrode, and the reaction time to 60 minutes. After the reaction, add polyacrylamide (PAM) to the wastewater at a dosage of 10mg / L for flocculation and precipitation for 30 minutes to remove suspended matter and some organic matter in the wastewater.

[0069] Biological treatment: The pretreated wastewater enters the anaerobic bioreactor, and the temperature in the anaerobic reactor is controlled at 38°C, the pH value is 7.2, and the hydraulic retention time is 24 hours. The anaerobic wastewater enters the aerobic bioreactor, and is inoculated with domesticated composite microbial flora, and the dissolved oxygen is controlled at 4 mg / L, the pH value is 7.5, and the hydraulic retention time is 12 hours.

[0070] Sulfide treatment: The wastewater after aerobic treatment enters the sulfide treatment unit, and ferrous sulfate is added to make the molar ratio of iron ions to sulfide 2.0, and the reaction time is 30 minutes. The supernatant after precipitation enters the catalytic oxidation reactor, and a catalytic oxidation system with manganese dioxide as the catalyst is added, the temperature is 50°C, and the reaction time is 40 minutes.

[0071] Advanced oxidation treatment: The wastewater after sulfide treatment enters the photocatalytic oxidation reactor, with silver-doped titanium dioxide as the photocatalyst. The dosage of the photocatalyst is 1.0g / L, and the reaction takes place under ultraviolet light for 90 minutes.

[0072] Membrane separation and concentration: The wastewater after photocatalytic oxidation is filtered and concentrated through ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane in turn. The molecular weight cutoff of ultrafiltration membrane is 50kDa, the molecular weight cutoff of nanofiltration membrane is 500Da, and the desalination rate of reverse osmosis membrane is 97%. The membrane concentrate enters the distillation device to recover organic raw materials such as butadiene.

[0073] Sludge treatment: The sludge generated during the wastewater treatment process is first subjected to biological drying treatment at a temperature of 35°C and a ventilation volume of 0.3m 3 / (kg·h), the drying time was 5 days. Then polyaluminium chloride (PAC) was added at a dosage of 15mg / L for dehydration treatment.

[0074] Intelligent control: Install sensors in each processing unit to monitor water quality indicators, temperature, pH value, dissolved oxygen and other parameters in real time. The intelligent control system automatically adjusts the pump flow, fan air volume, dosage of the agent and other parameters according to the monitoring data.

[0075] Comparative Example 1

[0076] The traditional butadiene extraction wastewater treatment process is adopted, that is, simple coagulation and sedimentation are used for pretreatment, ordinary activated sludge method is used for biological treatment, and simple oxidation method is used for sulfide treatment. There are no subsequent treatment steps such as advanced oxidation and membrane separation.

[0077] Performance Testing

[0078] Water quality index test: The chemical oxygen demand (COD), sulfide, phenols and other indicators of the wastewater before and after treatment are tested using national standard testing methods.

[0079] Treatment cost calculation: The amount of chemical agents used, energy consumption, etc. during the treatment process of Example 1 and Comparative Example 1 were counted to calculate the treatment cost.

[0080] Calculation of water resource recovery rate: The water resource recovery rate is calculated by measuring the volume of wastewater before and after treatment.

[0081] Sludge production statistics: Statistics on the amount of sludge produced during the treatment process and calculation of the sludge reduction ratio.

[0082] Test Results

[0083] Test items Example 1 Example 2 Example 3 Comparative Example 1 COD removal rate (%) 96 95 96 70 Sulfide removal rate (%) 99.5 99.6 99.3 85 Processing cost (yuan / ton) 3.5 3.5 3.5 6.0 Water resource recovery rate (%) 75 78 74 30 Sludge reduction ratio (%) 55 57 52 20

[0084] It can be seen from the test results that the wastewater treatment process of the present invention is significantly superior to the traditional process in terms of organic matter removal, sulfide treatment, treatment cost, water resource recovery and sludge reduction.

[0085] Precautions

[0086] During the pretreatment stage, it is necessary to ensure the normal operation of the ultrasound-microelectrolysis reactor, regularly check the status of the ultrasonic equipment and microelectrolysis electrodes, and replace damaged parts in time.

[0087] During the biological treatment process, attention should be paid to the cultivation and domestication of microbial flora, regular replenishment of nutrients, control of reaction conditions, and avoidance of microbial poisoning.

[0088] When treating sulfides, the dosage of iron salt and reaction conditions must be strictly controlled to prevent the escape of hydrogen sulfide gas.

[0089] In advanced oxidation treatment, attention should be paid to the activity and service life of the photocatalyst, and the photocatalytic reactor should be cleaned and maintained regularly.

[0090] During the membrane separation and concentration process, the membrane components must be cleaned and backwashed regularly to prevent membrane pollution and affect the treatment effect and water resource recovery rate.

[0091] Intelligent control systems must perform data calibration and maintenance regularly to ensure the accuracy of monitoring data and the effectiveness of control.

[0092] Summarize

[0093] The present invention uses a novel pretreatment technology, such as an ultrasound-micro-electrolysis combined pretreatment process, by innovating and improving the butadiene extraction wastewater treatment process. The cavitation effect of ultrasound and the new ecological hydrogen and ferrous ions generated in the micro-electrolysis process are used to break the chemical bonds of the refractory organic matter in the wastewater, improve its biodegradability, and create favorable conditions for subsequent treatment.

[0094] Synergistic biological treatment technology: Develop a new type of composite microbial flora, screen and domesticate microorganisms that have the ability to degrade pollutants such as aromatic hydrocarbons, sulfides and phenols, and form a synergistic flora. At the same time, optimize the biological treatment process conditions, such as controlling the appropriate dissolved oxygen, pH value and hydraulic retention time, to improve the biological treatment efficiency and achieve simultaneous and efficient removal of multiple pollutants.

[0095] New sulfide treatment method: The sulfide in wastewater is treated by combining iron salt-sulfide co-precipitation with catalytic oxidation. Iron salt reacts with sulfide to form iron sulfide precipitation. By controlling the reaction conditions, the precipitation is made more stable and less likely to decompose and produce hydrogen sulfide. Then, the residual sulfide is catalytically oxidized by a catalyst to completely convert it into harmless sulfate to avoid secondary pollution.

[0096] Optimize advanced oxidation process: Select new photocatalytic oxidation system, such as photocatalyst based on titanium dioxide and doped with transition metal elements. Under the irradiation of ultraviolet or visible light, the photogenerated electrons and holes generated by the photocatalyst can efficiently oxidize and decompose the difficult-to-degrade organic matter in the wastewater, reduce the use of oxidants, and reduce treatment costs.

[0097] Integration of membrane separation and concentration technology: Integrate the membrane separation technologies such as ultrafiltration, nanofiltration and reverse osmosis, and select appropriate membrane components for graded filtration according to the particle size and properties of pollutants in the wastewater. Through membrane concentration technology, pollutants in wastewater can be further concentrated, the recovery rate of water resources can be improved, and the load of subsequent treatment can be reduced.

[0098] Resource recycling: In the process of wastewater treatment, we focus on the recycling of valuable substances. For example, we can recover organic raw materials such as butadiene from wastewater through distillation and other methods to achieve resource recycling and reduce production costs.

[0099] Intelligent control system: Establish an intelligent control system based on sensors and automatic control technology to monitor various parameters in the wastewater treatment process in real time, such as water quality indicators, equipment operation status, etc. Automatically adjust the treatment process parameters according to the monitoring data to ensure the stability and efficiency of the treatment process, while achieving energy conservation and emission reduction.

[0100] Sludge reduction treatment: The sludge generated during wastewater treatment is treated by combining biological drying and chemical conditioning. Biological drying uses the metabolism of microorganisms to reduce the water content of sludge, while chemical conditioning improves the dehydration performance of sludge by adding specific chemical agents, reduces the volume and weight of sludge, and reduces the cost of sludge treatment.

[0101] Process optimization and integration: Through the optimal combination of various treatment units, a compact and efficient wastewater treatment process is formed. The connection loss between treatment units is reduced, the overall treatment efficiency is improved, and the equipment footprint and construction cost are reduced.

[0102] Application of green chemicals: In the process of wastewater treatment, environmentally friendly chemicals are selected, such as biodegradable flocculants, catalysts, etc. After these chemicals take effect, they will not remain in the environment or cause secondary pollution, which meets the requirements of green environmental protection.

[0103] It successfully solved the problems of incomplete removal of organic matter, difficult sulfide treatment, high treatment cost, complex process flow and low water resource recovery rate in the existing technology. The treatment process has the advantages of high efficiency, low cost and environmental protection, and can achieve standard discharge of wastewater and recycling of water resources, with broad application prospects and promotion value.

Claims

1. A wastewater treatment process for butadiene extraction, characterized in that: The following steps are involved: The butadiene extraction wastewater is introduced into an ultrasound-micro-electrolysis reactor for pretreatment, wherein the ultrasound frequency is 20-40kHz, the power is 300-500W, the micro-electrolysis electrode is an iron-carbon electrode, and the reaction time is 30-60 minutes; after the reaction, a flocculant is added for flocculation precipitation, wherein the flocculant is polyacrylamide, and the dosage is 5-10 mg / L; the pretreated wastewater enters an anaerobic bioreactor for treatment, wherein the temperature in the anaerobic reactor is controlled to be 35-38°C, the pH value is 6.8-7.2, and the hydraulic retention time is 12-24 hours; the anaerobic wastewater enters an aerobic bioreactor, wherein the aerobic reactor is inoculated with a domesticated composite microbial flora, wherein the dissolved oxygen is controlled to be 2-4 mg / L, the pH value is 7.0-7.5, and the hydraulic retention time is 8-12 hours.

2. The wastewater treatment process according to claim 1, characterized in that: The wastewater after aerobic treatment enters the sulfide treatment unit, and ferrous sulfate is added to the wastewater to make the molar ratio of iron ions to sulfides 1.5-2.0, and the reaction generates iron sulfide precipitation, and the reaction time is 20-30 minutes; the supernatant after precipitation enters the catalytic oxidation reactor, and a catalytic oxidation system with manganese dioxide as a catalyst is added. Under the conditions of a temperature of 40-50°C and a reaction time of 30-40 minutes, the residual sulfide is oxidized to sulfate.

3. The wastewater treatment process according to claim 2, characterized in that: The wastewater after sulfide treatment enters the photocatalytic oxidation reactor, with silver-doped titanium dioxide as the photocatalyst. The dosage of the photocatalyst is 0.5-1.0 g / L, and the photocatalytic oxidation reaction is carried out under ultraviolet light for 60-90 minutes.

4. The wastewater treatment process according to claim 3, characterized in that: The wastewater after photocatalytic oxidation is filtered and concentrated through an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane in sequence. The ultrafiltration membrane has a molecular weight cutoff of 10-50 kDa, the nanofiltration membrane has a molecular weight cutoff of 100-500 Da, and the reverse osmosis membrane has a desalination rate of more than 95%.

5. The wastewater treatment process according to claim 4, characterized in that: The membrane concentrate is distilled to recover the organic raw material of butadiene; the sludge produced in the wastewater treatment process is first subjected to biological drying treatment at a temperature of 30-35°C and a ventilation volume of 0.2-0.3m 3 / (kg·h), the drying time is 3-5 days, and then a chemical conditioner is added, wherein the chemical conditioner is polyaluminium chloride, and the dosage is 10-15mg / L, and dehydration treatment is carried out to reduce the moisture content of the sludge to below 60%.

6. The wastewater treatment process according to any one of claims 1 to 5, characterized in that: Sensors are installed at various stages of wastewater treatment to monitor water quality indicators, temperature, pH value, and dissolved oxygen parameters in real time; the intelligent control system automatically adjusts the operating parameters of each treatment unit based on the monitoring data, including the flow rate of the pump, the air volume of the fan, and the dosage of the reagent.

7. A treated water obtained by treating butadiene extraction wastewater using the wastewater treatment process according to any one of claims 1 to 5, characterized in that: The chemical oxygen demand (COD) of the treated water is lower than 50 mg / L, and the sulfide content is lower than the national emission standard.

8. A method for treating sludge recovered from butadiene extraction wastewater using the wastewater treatment process according to any one of claims 1 to 5, characterized in that: The water content of the sludge is lower than 60%, and after biological drying and chemical conditioning, the volume and weight of the sludge are reduced by 50%-60% compared with before treatment.