Treatment method and treatment device for wastewater generated in co-production of propylene oxide and methyl tert-butyl ether

Abstract

The invention belongs to the technical field of microbial electrochemistry, and particularly relates to a treatment method and a treatment device for wastewater generated in co-production of propylene oxide and methyl tert-butyl ether. The treatment method for the wastewater generated by co-production of the epoxypropane and the methyl tert-butyl ether comprises the following steps: carrying out anaerobic biological treatment on the wastewater generated by co-production of the epoxypropane and the methyl tert-butyl ether and a microbial synergist, and applying voltage in the anaerobic biological treatment process; the microbial synergist comprises lactic acid, dipotassium phosphate, ammonium chloride, magnesium chloride, calcium chloride, zinc sulfate, sodium bicarbonate, ferrous sulfate, fulvic acid, manganese chloride, EDTA-2Na and trace elements, and the trace elements comprise boric acid, copper sulfate, sodium molybdate, nickel chloride and cobalt chloride. By regulating and controlling the components of the microbial synergist and utilizing the electrochemical technology and the synergistic effect of the microbial synergist and anaerobic reaction, the growth environment of microorganisms is optimized, the pollutant degradation rate and the methane content in the anaerobic digestion process are increased, and the wastewater treatment efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial electrochemistry, and particularly relates to a method and a device for treating wastewater produced by co-producing propylene oxide and methyl tert-butyl ether. Background Art

[0002] The wastewater generated during the co-production of propylene oxide and methyl tert-butyl ether belongs to petrochemical wastewater, which has strong biodegradability resistance. It usually contains high concentrations of organic pollutants and toxic chemical substances, posing a serious threat to the ecological environment. Traditional physicochemical treatment methods, such as adsorption, precipitation, and chemical oxidation, although can remove some pollutants in the wastewater to a certain extent, these methods generally have defects such as high treatment cost, complex operation, and secondary pollution, and are difficult to meet the requirements of sustainable development of modern industry. In addition, a large amount of chemical reagents are used in the chemical oxidation process, which not only increases the cost but also may bring new environmental pollution. Therefore, there is an urgent need for a green, efficient, and sustainable wastewater treatment method.

[0003] In this context, anaerobic biological treatment technology has gradually become a powerful means for treating the wastewater produced by co-producing propylene oxide and methyl tert-butyl ether due to its good organic pollutant removal effect and low operating cost. However, there are various substances in the wastewater produced by co-producing propylene oxide and methyl tert-butyl ether that have toxic inhibitory effects on anaerobic microorganisms, such as petroleum-based, phenolic, ketonic, and ether compounds. These components significantly reduce the metabolic activity of anaerobic microorganisms, resulting in low efficiency of traditional anaerobic treatment. Therefore, it is difficult to achieve efficient purification of this type of wastewater solely by relying on conventional anaerobic biological treatment methods.

[0004] In recent years, the electric field-assisted anaerobic treatment technology, as an innovative treatment method, has received extensive attention because it can effectively improve the microbial activity. The applied electric field can enhance the permeability of the microbial cell membrane and promote the transport of substrates and nutrients, thereby improving the metabolic ability of anaerobic microorganisms. At the same time, appropriate electric field conditions can accelerate the redox reaction of organic matter in the wastewater and improve the purification efficiency of the wastewater. This technology shows broad application prospects in the treatment of highly toxic and difficult-to-degrade organic wastewater.

[0005] The Chinese patent application with the publication number CN113023875A, published on June 25, 2021, discloses a bioelectrochemical device with an internal rotating electrode for treating refractory wastewater, including an anaerobic reactor, an anode and a cathode respectively arranged in the anaerobic reactor, and a reference electrode arranged between the anode and the cathode. The anode and the cathode are respectively rotatably arranged relative to the anaerobic reactor, and the rotation directions of the anode and the cathode are the same. This device can effectively improve the disadvantages such as the accumulation of volatile fatty acids and the long start-up time in the anaerobic system, and at the same time promote the synergistic effect between electrochemically active bacteria and traditional anaerobic bacteria, realizing the efficient removal of refractory organic matter. The COD content in the refractory wastewater is 2500 ± 200 mg / L, and the BOD5 content is 300 ± 50 mg / L.

[0006] However, the above device only aims at the treatment of high-COD wastewater and does not disclose the treatment of propylene oxide co-producing methyl tert-butyl ether wastewater containing high concentrations of organic pollutants and toxic chemicals. The anaerobic treatment efficiency of this type of wastewater is still relatively low. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for treating propylene oxide co-producing methyl tert-butyl ether wastewater to solve the problem of relatively low existing anaerobic treatment efficiency.

[0008] The second purpose of the present invention is to provide a treatment device for propylene oxide co-producing methyl tert-butyl ether wastewater to solve the problem of relatively low treatment efficiency of the existing treatment device.

[0009] In order to solve the above technical problems, the technical solution of the method for treating propylene oxide co-producing methyl tert-butyl ether wastewater of the present invention is as follows:

[0010] A method for treating propylene oxide co-producing methyl tert-butyl ether wastewater includes the following steps: performing anaerobic biological treatment on propylene oxide co-producing methyl tert-butyl ether wastewater and a microbial synergist, and applying a voltage during the anaerobic biological treatment process; the microbial synergist includes lactic acid, dipotassium hydrogen phosphate, ammonium chloride, magnesium chloride, calcium chloride, zinc sulfate, sodium bicarbonate, ferrous sulfate, fulvic acid, manganese chloride, EDTA-2Na, and trace elements, and the trace elements include boric acid, copper sulfate, sodium molybdate, nickel chloride, and cobalt chloride.

[0011] The present invention is an improvement on the prior art, and provides a method for treating wastewater from the co-production of propylene oxide and methyl tert-butyl ether. By regulating the components of the microbial synergist, the activity of microorganisms in the system is enhanced, thereby improving the stability and treatment efficiency of wastewater treatment. The synergistic effect of electrochemical technology, microbial synergist and anaerobic reaction is utilized to optimize the growth environment of microorganisms, significantly increasing the pollutant degradation rate during anaerobic digestion and enhancing the methane content of biogas. Compared with the traditional anaerobic digestion method, the electrochemical enhanced anaerobic reactor can efficiently and stably complete the treatment of high-concentration methyl tert-butyl ether wastewater, improving the overall wastewater treatment efficiency.

[0012] The treatment method provided by the present invention does not rely on chemical agents and can effectively reduce the environmental burden during the treatment process. The organic pollutants in the wastewater are degraded through microbial metabolism, and the generated methane can be used for energy recovery, further reducing the demand for external energy, which meets the requirements of green and environmental sustainable development.

[0013] To further improve the anaerobic treatment efficiency, preferably, the microbial synergist includes the following components: lactic acid 2 - 2.5 g / L, dipotassium hydrogen phosphate 0.2 - 0.255 g / L, ammonium chloride 0.15 - 0.2 g / L, magnesium chloride hexahydrate 0.08 - 0.1 g / L, calcium chloride dihydrate 0.02 - 0.05 g / L, zinc sulfate heptahydrate 0.001 - 0.005 g / L, sodium bicarbonate 0.02 - 0.05 g / L, ferrous sulfate heptahydrate 0.005 - 0.010 g / L, fulvic acid 0.02 - 0.05 g / L, manganese chloride tetrahydrate 0.002 - 0.005 g / L, trace element solution 1 - 5 mL / L, EDTA-2Na 0.05 - 0.10 g / L and water; the trace element solution includes the following components: boric acid 0.1 - 0.15 g / L, copper sulfate pentahydrate 0.03 - 0.05 g / L, sodium molybdate 0.005 - 0.010 g / L, nickel chloride hexahydrate 0.004 - 0.005 g / L, cobalt chloride hexahydrate 0.003 - 0.005 g / L and water; the pH of the microbial synergist is 6.5 - 7.5.

[0014] To further improve the anaerobic treatment efficiency, preferably, the volume ratio of the wastewater from the co-production of propylene oxide and methyl tert-butyl ether to the microbial synergist during the anaerobic biological treatment process is (10 - 12):1.

[0015] By regulating key parameters such as pH value, oxidation-reduction potential (ORP), dissolved oxygen concentration, etc., the long-term stable operation of anaerobic reaction in a complex wastewater environment is ensured, while maintaining efficient pollutant degradation and methane generation.

[0016] Preferably, the voltage is applied in four stages during the anaerobic biological treatment process. The voltage applied in the first stage is 0.7 - 0.8V, the voltage applied in the second stage is 0.9 - 1.0V, the voltage applied in the third stage is 1.1 - 1.2V, and the voltage applied in the fourth stage is 1.3 - 1.4V.

[0017] Preferably, the pH during the anaerobic biological treatment process is 6.5 - 7.5, the temperature is 35 - 37°C, and the dissolved oxygen concentration is less than 0.1 mg / L.

[0018] To further improve the stability of the anaerobic reaction, preferably, microbial domestication is carried out before the anaerobic biological treatment. The microbial domestication includes the following steps: under the condition of applying voltage, the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist with a volume ratio of (4 - 5):1 are subjected to anaerobic biological treatment until the current drops below 10% of the highest current in the reaction system, and then the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist are updated for anaerobic biological treatment until the current is stable.

[0019] The technical solution of the treatment device for the wastewater from the co-production of propylene oxide and methyl tert-butyl ether of the present invention is as follows:

[0020] A treatment device for the wastewater from the co-production of propylene oxide and methyl tert-butyl ether includes an anaerobic biological treatment reactor. An anode plate and a cathode plate extending towards the top of the anaerobic biological treatment reactor are provided on the bottom wall of the anaerobic biological treatment reactor, and the anode plate and the cathode plate are arranged at intervals.

[0021] In the treatment device for the wastewater from the co-production of propylene oxide and methyl tert-butyl ether provided by the present invention, the anode plate and the cathode plate arranged at intervals on the bottom wall of the anaerobic biological treatment reactor can provide a large specific surface area in the arrangement mode of the anode and cathode plates, making the voltage distribution more uniform, avoiding too high or too low local voltage. The electrochemical technology, the microbial synergist and the anaerobic reaction play a synergistic role, which can significantly improve the pollutant degradation rate in the two-phase anaerobic digestion process and increase the methane content of the biogas.

[0022] To further improve the synergistic effect of electrochemistry and anaerobic reaction, preferably, when the length, width and height of the inner cavity of the anaerobic biological treatment reactor are L, W and H respectively, the length of the anode plate and the cathode plate is The width is The height is The distance between the anode plate and the cathode plate is

[0023] Preferably, a three-phase separation device is provided on the upper side of the anode plate and the cathode plate in the anaerobic biological treatment reactor. The anaerobic biological treatment reactor adopts an optimized three-phase separation device, anode and cathode plates to achieve efficient gas, liquid and solid separation, maintain the stability of the reactor, reduce the complexity of operation and maintenance, and adapt to different wastewater treatment requirements through high-precision voltage regulation, showing excellent applicability and economic benefits.

[0024] To further improve the resource utilization rate, preferably, a circulating liquid outlet is provided on the side wall below the three-phase separation device of the anaerobic biological treatment reactor, and a circulating liquid inlet is provided on the side wall close to the bottom wall of the anaerobic biological treatment reactor. The circulating liquid outlet and the circulating liquid inlet are connected through a reflux pipe, and a circulating pump is provided on the reflux pipe. After the reaction area below the anaerobic biological treatment reactor undergoes anaerobic biological treatment, the concentration of pollutants in the solution above is reduced compared to that above. By using this circulation device, the toxic substances and pollutants in the solution above the reactor can be diluted, the inhibitory effect on microorganisms can be reduced, the anti-load capacity of the reactor can be enhanced, and the mixing of mud and water can be strengthened.

[0025] To further accelerate the efficiency of anaerobic biological reactions, preferably, the anaerobic biological treatment reactor is provided with a stirring device for stirring the materials in the anaerobic biological treatment reactor. The stirring device is used to fully mix the substrate and anaerobic sludge to ensure uniform distribution of the materials in the reactor and maintain temperature uniformity.

[0026] To further facilitate the collection of the gas and liquid generated by anaerobic biological reactions, preferably, a gas collector is provided at the top of the anaerobic biological treatment reactor for collecting the gas separated by the three-phase separation device, and a liquid outlet is provided on the side wall of the anaerobic biological treatment reactor close to the top of the three-phase separation device.

[0027] To achieve real-time monitoring of the pH and oxidation-reduction potential in the reaction system for further regulation of anaerobic biological reactions, preferably, a pH / ORP composite probe is provided between the anode plate and the cathode plate arranged at intervals for monitoring the system pH and oxidation-reduction potential during the anaerobic biological reaction process. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the treatment device for propylene oxide co-producing methyl tert-butyl ether wastewater in Embodiment 1 of the present invention;

[0029] Figure 2 is Figure 1 a top view of;

[0030] Figure 3 It is a change diagram of the current fluctuating periodically after microbial domestication in the treatment method of Embodiment 2 of the present invention;

[0031] Figure 4Graphs of COD concentration and voltage changes at different treatment stages;

[0032] Figure 5 Graphs of COD removal rate and volumetric loading changes at different treatment stages;

[0033] Figure 6 Graph of effluent pH changes at different treatment stages;

[0034] Figure 7 Graph of effluent VFAs concentration changes at different treatment stages;

[0035] In the attached drawings: 1. Anaerobic biological treatment reactor 1; 2. Anode plate; 3. Cathode plate; 4. Three-phase separation device; 5. Motor; 6. Discharge port; 7. Stirring shaft; 8. Stirring paddle; 9. pH / ORP composite probe; 10. Controller; 11. Sludge area; 12. Anode plate holder; 13. Bottom wall; 14. Constant voltage DC power supply; 15. Gas collector; 16. Inlet; 17. Outlet; 18. Recirculating liquid outlet; 19. Recirculating liquid inlet; 20. Recirculation pump; 21. Cathode plate holder. Detailed implementation mode

[0036] The technical concept of the method for treating propylene oxide co-produced methyl tert-butyl ether wastewater of the present invention is as follows:

[0037] The microbial synergist (nutrient for microorganisms) is compounded by inorganic substances, organic substances and various additives. By using the organic biochemical reactions of each component, through the colloid chemical process, chemical reaction process and microbial oxidation process, the microbial activity and decomposition ability are enhanced, the rapid propagation and domestication of microorganisms are promoted, the number of microbial populations is increased, and at the same time, the stability and balance of the microbial population system can be maintained, and the high efficiency, stability and shock resistance of the sewage treatment system can be maintained.

[0038] The existing methods for treating refractory wastewater and bioelectrochemical devices carry out anaerobic reactions under voltage conditions to promote the synergistic effect between electrochemically active bacteria and traditional anaerobic bacteria, and set the anode and cathode to be able to rotate relative to the anaerobic reactor respectively. The swirling state brought by the rotation can shorten the film formation time of electrochemically active bacteria and promote the enrichment of electrochemically active bacteria, realizing the co-removal of refractory pollutants at the anode and cathode.

[0039] However, the present invention significantly improves the pollutant degradation rate in the anaerobic digestion process by applying voltage during the anaerobic biological treatment process and regulating the composition of the microbial synergist, and using the synergistic effect of electrochemistry technology, microbial synergist and anaerobic reaction.

[0040] The treatment method of wastewater co - producing propylene oxide and methyl tert - butyl ether of the present invention includes the following steps: microbial domestication is carried out before anaerobic biological treatment. Anaerobic biological treatment is carried out on the wastewater co - producing propylene oxide and methyl tert - butyl ether and microbial synergist with a volume ratio of (10 - 12):1. During the anaerobic biological treatment process, a voltage of 0.7 - 1.4V is applied; the pH during the anaerobic biological treatment process is 6.5 - 7.5, the temperature is 35 - 37°C, and the dissolved oxygen concentration is lower than 0.1mg / L.

[0041] In a specific embodiment, the microbial domestication includes the following steps: Under the condition of applying a constant voltage, anaerobic biological treatment is carried out on the wastewater co - producing propylene oxide and methyl tert - butyl ether and microbial synergist with a volume ratio of (4 - 5):1. When the current drops below 10% of the highest current in the reaction system, more than half of the volume of the wastewater co - producing propylene oxide and methyl tert - butyl ether and microbial synergist is replaced for anaerobic biological treatment, and the current rebounds until the current shows periodic fluctuations.

[0042] In a specific embodiment, the initial bacterial source during anaerobic biological treatment comes from anaerobic sludge in the activated sludge system of an industrial sewage treatment plant. This sludge is rich in microbial populations and has a high organic matter degradation ability; before use, the activated sludge is washed, filtered, and precipitated to remove inorganic impurities, particulate matter, suspended impurities, and dissolved impurities; after washing, the water is filtered out with a sieve.

[0043] In a specific embodiment, the anaerobic biological treatment is carried out in an anaerobic bioreactor. A mixed solution formed by the wastewater co - producing propylene oxide and methyl tert - butyl ether and microbial synergist and anaerobic sludge is added to the anaerobic bioreactor for anaerobic biological treatment, and a voltage is applied during the anaerobic biological treatment process; the addition amount of anaerobic sludge accounts for 30% - 40% of the volume of the anaerobic biological treatment reactor, and the addition amount of anaerobic sludge and the mixed solution is 60 - 70% of the volume of the anaerobic biological treatment reactor.

[0044] It can be understood that the pH of the microbial synergist is adjusted to 6.5 - 7.5. When it is added to the anaerobic reaction system together with the wastewater, the pH of the system will change, and then the pH is adjusted again to make the pH during the anaerobic biological treatment process 6.5 - 7.5.

[0045] The present invention is described in detail below in conjunction with specific embodiments, but the implementation manners of the present invention are not limited thereto. Obviously, the following embodiments are only a part of the examples of the present invention. For those skilled in the art, without creative labor, other similar implementation schemes can be obtained, which should all be regarded as the protection scope of the present invention.

[0046] I. Specific embodiment of the treatment device for wastewater co - producing propylene oxide and methyl tert - butyl ether of the present invention

[0047] Example 1

[0048] The treatment device for the wastewater co - produced with propylene oxide and methyl tert - butyl ether in this example, as shown in Figure 1 and Figure 2 , includes an anaerobic biological treatment reactor 1. The length of the inner cavity of the anaerobic biological treatment reactor 1 is 12 cm, the width is 8 cm, and the height is 8 cm. The bottom wall 13 of the anaerobic biological treatment reactor 1 is provided with an anode plate 2 and a cathode plate 3 which are opposite to each other. Specifically, the bottom wall 13 of the anaerobic biological treatment reactor 1 is provided with an anode plate holder 12 and a cathode plate holder 21. The anode plate holder 12 and the cathode plate holder 21 are respectively installed with the anode plate 2 and the cathode plate 3. The length of the anode plate 2 and the cathode plate 3 is 2 cm, the width is 5 cm, and the height is 5 cm. The distance between the anode plate 2 and the cathode plate 3 is 3 cm. It should be noted that the lengths and widths of the anaerobic biological treatment reactor 1, the anode plate, and the cathode plate are defined in terms of the length (horizontal) and width (vertical) directions in Figure 2 , and the height is defined in terms of the height (vertical) direction in Figure 1 .

[0049] The anode plate holder 12 and the cathode plate holder 21 are respectively connected to the positive and negative electrodes of a constant - voltage DC power supply 14 to form a closed loop, providing a voltage to form an electric field in the reactor. The anode plate 2 is made of a graphite plate, and the cathode plate 3 is made of a titanium plate. The voltage range of the constant - voltage DC power supply 14 is 0 V to 5 V, and the voltage adjustment accuracy is 0.01 V.

[0050] The anaerobic biological treatment reactor 1 is provided with a three - phase separation device 4 on the upper side of the anode plate 2 and the cathode plate 3 for effectively separating gas, liquid, and solid sludge. A gas collector 15 is provided above the three - phase separation device 4 for collecting the separated gas. The anaerobic biological treatment reactor 1 is provided with a liquid outlet 17 on the side wall at the upper part of the three - phase separation device 4 for discharging the separated liquid. The separated solid sludge precipitates back into the anaerobic biological treatment reactor 1 to continue the anaerobic biological reaction.

[0051] The anaerobic biological treatment reactor 1 is provided with a stirring device. The stirring device includes a motor 5 arranged at the top of the anaerobic biological treatment reactor 1 and a stirring shaft 7 connected to the motor 5. The stirring shaft 7 passes through the three - phase separation device 4 and extends into the interior of the anaerobic biological treatment reactor 1. The part of the stirring shaft 7 located inside the anaerobic biological treatment reactor 1 is evenly provided with stirring paddles 8. The bottom of the stirring shaft 7 extends into the sludge area 11 to fully mix the substrate and anaerobic sludge, ensuring uniform distribution of the materials in the reactor and maintaining temperature uniformity. It should be noted that the sludge area 11 refers to the position where the muddy water mixture formed by the mixture of anaerobic sludge, wastewater, and microbial synergist mainly undergoes anaerobic biological reaction, rather than referring to the interface of the sludge.

[0052] The anaerobic biological treatment reactor 1 is provided with a circulating liquid inlet 19 on the side wall near the bottom wall 13, and a circulating liquid outlet 18 on the side wall near the bottom of the three-phase separation device. The circulating liquid inlet 19 and the circulating liquid outlet 18 are connected through a reflux pipe, and a circulating pump 20 is provided on the reflux pipe, which is used to reflux the sludge mixture in the upper part of the anaerobic biological treatment reactor 1 to the lower part. The circulating liquid inlet 19, the circulating pump 20 and the circulating liquid outlet 18 constitute the internal solution circulation in the anaerobic biological treatment reactor 1.

[0053] Inside the anaerobic biological treatment reactor 1, a pH / ORP composite probe 9 is provided at a position between the anode plate 2 and the cathode plate 3. The pH / ORP composite probe 9 is connected to a controller 10. The pH / ORP composite probe 9 is used to detect the changes in pH and ORP in the anaerobic biological treatment reactor 1 in real time and feed them back to the controller 10. The controller 10 controls the start and stop of the circulating pump 20. It can be understood that the controller 10 can also control the rotation speed of the circulating pump 20 to control the flow rate of the circulating liquid.

[0054] The bottom side wall of the anaerobic biological treatment reactor 1 is provided with a discharge port 6 and a liquid inlet 16. The liquid inlet 16 is located above the discharge port 6, and the discharge port 6 is used to discharge sludge.

[0055] II. Specific embodiments of the method for treating wastewater from co-production of propylene oxide and methyl tert-butyl ether according to the present invention

[0056] Example 2

[0057] The method for treating wastewater from co-production of propylene oxide and methyl tert-butyl ether in this example is carried out in the treatment device of Example 1. The specific method is as follows:

[0058] Before the processing device is officially started, microbial domestication is carried out: in an anaerobic environment, a constant voltage of 0.7 V is applied between the anode plate 2 and the cathode plate 3 by using the constant voltage DC power supply 14. A mixed solution formed by the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist in a volume ratio of 4:1 is added to the anaerobic biological treatment reactor 1, and anaerobic sludge is added. The addition amount of the anaerobic sludge accounts for 30% of the volume of the anaerobic biological treatment reactor 1. The addition amount of the anaerobic sludge and the mixed solution is 70% of the volume of the anaerobic biological treatment reactor 1, so that the microorganisms in the anaerobic sludge conduct current with the electrodes. When the current between the anode plate 2 and the cathode plate 3 in the anaerobic biological treatment reactor 1 drops below 10% of the maximum current, a mixed solution formed by the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist in an equal proportion is used to replace half of the volume of the mixed solution in the reactor to continue to promote the growth and enrichment of microorganisms, and the current increases. As the anaerobic biological reaction proceeds, the current gradually decreases. When it drops below 10% of the maximum current, a mixed solution formed by the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist in an equal proportion is used to replace half of the volume of the mixed solution in the reactor again. Repeat the above operation until the current shows periodic fluctuations. The current shows periodic fluctuations as Figure 3 shown; during domestication, the motor 5, the three-phase separation device 4, the pH / ORP composite probe 9, and the circulation pump 20 are all turned on, and the rotation speed of the circulation pump 20 is 40 rpm.

[0059] The microbial synergist is composed of the following components: lactic acid 2.3470 g / L, dipotassium hydrogen phosphate 0.2290 g / L, ammonium chloride 0.1660 / L, magnesium chloride hexahydrate 0.0895 g / L, calcium chloride dihydrate 0.0251 g / L, zinc sulfate heptahydrate 0.0011 g / L, sodium bicarbonate 0.0260 g / L, ferrous sulfate heptahydrate 0.0062 g / L, fulvic acid 0.0285 g / L, manganese chloride tetrahydrate 0.0023 g / L, trace element solution 1 mL / L, EDTA-2Na 0.05 g / L and water; the trace element solution is composed of the following components: boric acid 0.144 g / L, copper sulfate pentahydrate 0.0368 g / L, sodium molybdate 0.0055 g / L, nickel chloride hexahydrate 0.0040 g / L, cobalt chloride hexahydrate 0.0032 g / L and water; the pH of the microbial synergist is 6.5 - 7.5, which is the optimal growth range for anaerobic microorganisms and can also ensure the activity of the EDTA chelating agent.

[0060] The preparation method of the microbial synergist is as follows: Dissolve lactic acid, dipotassium hydrogen phosphate, ammonium chloride, magnesium chloride hexahydrate, calcium chloride dihydrate, sodium bicarbonate, ferrous sulfate heptahydrate, fulvic acid, manganese chloride tetrahydrate, zinc sulfate heptahydrate, and trace element solution in appropriate deionized water in sequence according to the above component composition to ensure complete dissolution; then add EDTA-2Na to the dissolved basic components and stir evenly to ensure its complete dissolution; finally, adjust the pH of the solution to between 6.5 and 7.5.

[0061] After the microbial domestication is completed, start the treatment device, and continuously introduce the mixed solution of propylene oxide co-producing methyl tert-butyl ether wastewater and the microbial synergist from the liquid inlet 16 of the anaerobic biological treatment reactor 1 at a volume ratio of 10:1. The influent COD concentration is 2500 - 4000 mg / L, and the petroleum substances concentration is 90 - 120 mg / L; use anaerobic sludge as the inoculum source.

[0062] Keep the hydraulic retention time in the anaerobic biological treatment reactor 1 at 3 days, the pH value between 6.5 and 7.5, the temperature controlled at 35 - 37 °C, and the dissolved oxygen concentration controlled below 0.1 mg / L.

[0063] The treatment device operates for 65 days in total. The experiment is divided into four stages. The voltage applied in the first stage is 0.7 V, the voltage applied in the second stage is 0.9 V, the voltage applied in the third stage is 1.1 V, and the voltage applied in the fourth stage is 1.3 V. During the anaerobic biological treatment process, the pH / ORP composite probe 9 continuously detects the pH and ORP changes in the anaerobic biological treatment reactor 1 and feeds them back to the controller 10. When the pH is not within the set range, the system pH is adjusted to 6.5 - 7.5 by adding acid or base externally. When the ORP is not within the set range, the ORP is controlled to be in a stable state by controlling the influent flow rate, etc.; when the treatment device starts to operate, the controller 10 controls the opening of the circulation pump 20, and the rotation speed of the circulation pump 20 is 40 rpm. The treatment method of the propylene oxide co-producing methyl tert-butyl ether wastewater in this example is denoted as R1.

[0064] III. Comparative Example

[0065] Comparative Example 1

[0066] The treatment method of the propylene oxide co-producing methyl tert-butyl ether wastewater in this comparative example is basically the same as that in Example 2, except that no voltage is applied during the microbial domestication process and the subsequent start-up process of the treatment device. The treatment method in this comparative example is denoted as R2.

[0067] Comparative Example 2

[0068] The treatment method of the propylene oxide co-producing methyl tert-butyl ether wastewater in this comparative example is carried out in the treatment device of Example 1. The specific method is as follows:

[0069] Before the formal start of the processing device, microbial domestication was carried out, and the domestication method was the same as that in Example 2. The microbial synergist in this comparative example consisted of the following components: 0.94 g / L glucose, 0.01 g / L yeast powder, 0.064 g / L HCl, 0.022 g / L KH2PO4, 0.05 g / L NaCl, 0.1 g / L EDTA-2Na, 0.075 g / L NaHCO3, 0.025 g / L MgSO4·7H2O, 0.025 g / L FeSO4·7H2O, 0.025 g / L CaCl2, 0.018 g / L FeSO4·7H2O, 0.009 g / L H3BO3, 0.16 g / L CuSO4·7H2O, 0.62 g / L MnCl2·4H2O, 0.27 g / L ZnSO4·5H2O, 0.12 g / L NiCl2·6H2O.

[0070] After domestication, a mixed solution of propylene oxide co-producing methyl tert-butyl ether wastewater and the microbial synergist in the comparative example was continuously introduced from the liquid inlet 16 of the anaerobic biological treatment reactor 1 at a volume ratio of 10:1, and the influent COD concentration was 2500 - 4000 mg / L; anaerobic sludge was used as the inoculum source. The hydraulic retention time in the anaerobic biological treatment reactor 1 was maintained at 3 days, the pH value was maintained between 6.5 and 7.5, the temperature was controlled at 35 - 37 °C, and the dissolved oxygen concentration was controlled below 0.1 mg / L.

[0071] The reactor operated stably for 30 d, and the applied voltage was 1.3 V. The results showed that when the influent concentration was 4000 mg / L, the highest COD removal rate was only 52.5%.

[0072] IV. Experimental Examples

[0073] To evaluate the treatment effect of the treatment method for propylene oxide co-producing methyl tert-butyl ether wastewater of the present invention, the following key indicators were regularly monitored: COD concentration, petroleum substances concentration, pH value, dissolved oxygen concentration, and VFAs concentration. At the same time, the gas composition and gas production rate collected by the gas collector 15 in the anaerobic biological treatment reactor 1 were regularly measured to investigate the methane production capacity.

[0074] In the process of treating propylene oxide co-producing methyl tert-butyl ether production wastewater with a COD concentration of 2500 - 4000 mg / L, R1 showed significantly better COD removal effect than R2. The COD concentration and voltage changes in the four stages are as Figure 4 shown, where COD in is the influent COD concentration, and COD ef is the effluent COD concentration.

[0075] According to Figure 4 The calculated COD removal rate and volume load are as Figure 5 shown. From Figure 5 it can be seen that the highest COD removal rate of R1 reaches 74.05%, and the average COD removal rate is 61.89%, which is much higher than the highest COD removal rate of 52.5% in Comparative Example 2. In contrast, the highest COD removal rate of R2 is 64.99%, and the average COD removal rate is 55.39%. During the treatment period, the volume load gradually increases from 0.3 KgCOD / m 3 / d to 1.2 KgCOD / m 3 / d.

[0076] The pH changes of the effluent treated by the treatment methods of Example 2 and Comparative Example 1 at different stages are as Figure 6 shown. From Figure 6 it can be seen that the pH value of R1 is slightly higher than that of R2. The changes in the VFAs concentration of the effluent at different stages are as Figure 7 shown. From 20 to 65 d, the VFAs concentration in the effluent of the R1 system is lower than that of the R2 system, further indicating that under the action of electrochemistry, the conversion of VFAs to methane in the R1 system has been significantly improved.

[0077] The average concentration of petroleum substances in the effluent of R1 is 7.8 mg / L, which is lower than 10 mg / L and meets the first-level discharge requirements of the Comprehensive Wastewater Discharge Standard. The average concentration of petroleum substances in the effluent of R2 is 12.8 mg / L. By monitoring the gas composition and gas production rate in the gas collection system, the average methane production of R1 is 345 mL / d / mL, which is significantly higher than the gas production rate in R2 (220 mL / d / mL), indicating that electrochemistry stimulation significantly increases the methane production in the anaerobic reactor.

[0078] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the protection scope of the present invention. For ordinary technical staff in the technical field, simple modifications or equivalent replacements of the technical solution of the present invention all belong to the protection scope of the present invention.

Claims

1. A treatment method for wastewater co-produced in propylene oxide and methyl tert-butyl ether production, characterized in that, It includes the following steps: Anaerobic biological treatment is carried out on the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and a microbial synergist, and a voltage is applied during the anaerobic biological treatment process; the microbial synergist includes lactic acid, dipotassium hydrogen phosphate, ammonium chloride, magnesium chloride, calcium chloride, zinc sulfate, sodium bicarbonate, ferrous sulfate, fulvic acid, manganese chloride, EDTA-2Na and trace elements, and the trace elements include boric acid, copper sulfate, sodium molybdate, nickel chloride and cobalt chloride.

2. The treatment method of wastewater produced by co-producing propylene oxide and methyl tert-butyl ether according to claim 1, characterized in that, The microbial synergist includes the following components: 2 - 2.5 g / L of lactic acid, 0.2 - 0.255 g / L of dipotassium hydrogen phosphate, 0.15 - 0.2 g / L of ammonium chloride, 0.08 - 0.1 g / L of magnesium chloride hexahydrate, 0.02 - 0.05 g / L of calcium chloride dihydrate, 0.001 - 0.005 g / L of zinc sulfate heptahydrate, 0.02 - 0.05 g / L of sodium bicarbonate, 0.005 - 0.010 g / L of ferrous sulfate heptahydrate, 0.02 - 0.05 g / L of fulvic acid, 0.002 - 0.005 g / L of manganese chloride tetrahydrate, 1 - 5 mL / L of trace element solution, 0.05 - 0.10 g / L of EDTA-2Na and water; the trace element solution includes the following components: 0.1 - 0.15 g / L of boric acid, 0.03 - 0.05 g / L of copper sulfate pentahydrate, 0.005 - 0.010 g / L of sodium molybdate, 0.004 - 0.005 g / L of nickel chloride hexahydrate, 0.003 - 0.005 g / L of cobalt chloride hexahydrate and water; the pH of the microbial synergist is 6.5 - 7.

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3. The method for treating wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 1 or 2, characterized in that, During the anaerobic biological treatment process, the volume ratio of the wastewater from the co-production of propylene oxide and methyl tert-butyl ether to the microbial synergist is (10 - 12):

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4. The method for treating wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 1, characterized in that, During the anaerobic biological treatment process, the voltage is applied in four stages. The voltage applied in the first stage is 0.7 - 0.8 V, the voltage applied in the second stage is 0.9 - 1.0 V, the voltage applied in the third stage is 1.1 - 1.2 V, and the voltage applied in the fourth stage is 1.3 - 1.4 V.

5. The treatment method of wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 1, wherein, The pH during the anaerobic biological treatment process is 6.5 - 7.5, the temperature is 35 - 37 °C, and the dissolved oxygen concentration is lower than 0.1 mg / L.

6. The treatment method of wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 1, characterized in that, Microbial domestication is carried out before the anaerobic biological treatment. The microbial domestication includes the following steps: Under the condition of applying voltage, anaerobic biological treatment is carried out on the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist with a volume ratio of (4 - 5):1 until the current drops below 10% of the highest current in the reaction system, and then the wastewater from the co-production of propylene oxide and methyl tert-butyl ether and the microbial synergist are updated for anaerobic biological treatment until the current is stable.

7. A treatment device for wastewater from the co-production of propylene oxide and methyl tert-butyl ether, characterized in that, It includes an anaerobic biological treatment reactor. The bottom wall of the anaerobic biological treatment reactor is provided with an anode plate and a cathode plate extending towards the top of the anaerobic biological treatment reactor, and the anode plate and the cathode plate are arranged at intervals.

8. The treatment device for the wastewater produced by the co-production of propylene oxide and methyl tert-butyl ether according to claim 7, wherein, When the length, width, and height of the inner cavity of the anaerobic biological treatment reactor are L, W, and H respectively, the length of the anode plate and the cathode plate is The width is The height is The distance between the anode plate and the cathode plate is 9. The treatment device for wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 7, characterized in that, A three-phase separation device is arranged on the upper side of the anaerobic biological treatment reactor where the anode plate and the cathode plate are located.

10. The treatment device for wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 7, wherein, The anaerobic biological treatment reactor is provided with a circulating liquid outlet on the side wall below the three-phase separation device, and a circulating liquid inlet on the side wall near the bottom wall. The circulating liquid outlet and the circulating liquid inlet are connected through a reflux pipe, and a circulating pump is provided on the reflux pipe.

11. The treatment device for wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 7, characterized in that, The anaerobic biological treatment reactor is provided with a stirring device for stirring the materials in the anaerobic biological treatment reactor.

12. The treatment device for wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 11, wherein A gas collector is provided at the top of the anaerobic biological treatment reactor for collecting the gas separated by the three-phase separation device. The anaerobic biological treatment reactor is provided with a liquid outlet on the side wall near the top of the three-phase separation device.

13. The treatment device for wastewater from the co-production of propylene oxide and methyl tert-butyl ether according to claim 7, wherein, A pH / ORP composite probe is provided between the anode plate and the cathode plate arranged at intervals for monitoring the system pH and oxidation-reduction potential during the anaerobic biological reaction process.

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