Method for cooperatively treating cosmetic wastewater based on aerobic granular sludge-MBR-micro-nano ozone

Abstract

The invention discloses a method for cooperatively treating cosmetic wastewater based on aerobic granular sludge-MBR-micro-nano ozone, and belongs to the field of water treatment. According to the method, an aerobic granular sludge coupled MBR / micro-nano ozone oxidation combined process is constructed to treat the plastic cosmetic wastewater, the characteristics of AGS, MBR and micro-nano ozone disinfection processes are combined, and the method has the advantages of excellent synchronous nitrogen and phosphorus removal efficiency, high impact load resistance, membrane pollution reduction, good sterilization effect, no secondary pollution, energy utilization efficiency improvement and the like. The problems of incomplete removal of refractory organic matters, incomplete disinfection, secondary pollution, high operation cost and the like in the cosmetic wastewater treatment process can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for treating cosmetic wastewater based on aerobic granular sludge-MBR-micro-nano ozone cooperation, belonging to the field of water treatment. BACKGROUND

[0002] Cosmetic wastewater is mainly derived from cosmetic factories, beauty salons, medical cosmetic institutions, and mortuary cosmetic rooms, etc. Its water quality characteristics are significantly different from ordinary domestic sewage or industrial wastewater. It has the characteristics of high organic matter, potential toxicity, and large pH fluctuation. This type of wastewater is mainly composed of organic pollutants (whitening active ingredients, surfactants, oils and emulsifiers, preservatives, etc.), inorganic pollutants (heavy metals, salicylic acid, etc.), suspended solids (SS), microbial pollutants (pathogenic bacteria, biofilm residues), and other additives (silicone oil). It mainly contains three types of pollutants that need to be focused on: (1) nitrogen and phosphorus pollutants; (2) microbial pollutants; (3) persistent and difficult-to-degrade special pollutants such as cosmetics and preservatives, which mainly include benzophenone-3, arbutin, kojic acid, tranexamic acid, and 4-methoxysalicylic acid potassium. Although the concentration of this type of wastewater is low, the organic matter concentration of the influent is low, and the pretreatment process and ordinary activated sludge process are difficult to effectively remove it. Due to their biological toxicity, environmental persistence, and biological accumulation, they have significant environmental and health risks, and can have toxic effects on subsequent treatment processes, and even cause biochemical treatment processes to fail.

[0003] Patent CN 116813075 A discloses a method for treating cosmetic wastewater by cultivating aerobic granular sludge and domesticating AGS under low carbon-nitrogen ratio conditions. However, the present application found that although the above-mentioned patent has achieved certain excellent results in treating cosmetic wastewater, the treatment effect is still not ideal due to the presence of arbutin and kojic acid in cosmetic wastewater.

[0004] At the same time, for cosmetic and preservative difficult-to-degrade pollutants, the existing technology generally uses electro-Fenton-based advanced oxidation technology for removal, but electro-Fenton technology has the disadvantages of high reagent dosage and high sludge yield, which increases the difficulty and operating cost of the process.

[0005] Therefore, there is an urgent need to develop a biological-physicochemical combined process that can stably and efficiently treat cosmetic wastewater to improve treatment efficiency and reduce treatment cost. SUMMARY

[0006] TECHNICAL PROBLEM

[0007] At present, the treatment of cosmetic wastewater is mostly combined process of "pretreatment + biological treatment + advanced oxidation disinfection", such as "coagulation + biological contact oxidation + activated carbon adsorption", "Fenton oxidation + MBR + ultraviolet disinfection", etc. However, cosmetic wastewater contains complex pollutants such as arbutin, formaldehyde, heavy metals (such as mercury and arsenic), organic solvents, pathogenic microorganisms (bacteria and viruses), etc. Therefore, the existing technology has many problems in treating such wastewater, such as inhibition of biological treatment by high-toxicity organic matter, incomplete removal of refractory organic matter, incomplete disinfection, secondary pollution, and high operation cost.

[0008] Technical scheme

[0009] To solve the above technical problems, the present application provides a method for treating cosmetic wastewater based on aerobic granular sludge-MBR-micro-nano ozone. Aerobic granular sludge has good settling performance, high biomass, rich microbial diversity, strong impact load capacity, excellent denitrification performance, and is not prone to sludge bulking, etc. In recent years, research and application of aerobic granular sludge have increased. It is found that the combination of aerobic granular sludge and membrane process (AGS-MBR) for treating cosmetic wastewater can achieve excellent nitrogen and phosphorus removal performance. The use of aerobic granular sludge can improve the impact resistance, strengthen the biological treatment, and reduce the membrane pollution. Subsequently, the micro-nano aeration technology is coupled with ozone disinfection to oxidize and disinfect the effluent of the AGS-MBR process, which can achieve good sterilization effect, no secondary pollution, and improve the energy utilization efficiency. Based on the above analysis, the AGS-MBR-micro-nano ozone oxidation process can be used to treat cosmetic wastewater.

[0010] The present application provides a method for treating cosmetic wastewater, which uses AGS-MBR reaction device; the AGS-MBR reaction device is composed of an aerobic granular sludge reactor and an MBR reactor, which are separately placed and connected by a pipeline connecting the effluent outlet of the aerobic granular sludge reactor and the influent inlet of the MBR reactor;

[0011] The aerobic granular sludge reactor is a cylindrical sequencing batch reactor, and an aeration device is arranged at the bottom of the reactor, which uses a common aeration head; the MBR reactor is an integrated MBR reactor, and the membrane assembly selects polyvinylidene fluoride (PVDF) hollow fiber microfiltration membrane;

[0012] The method comprises the following steps:

[0013] (1) Inoculate sludge into the sequencing batch reactor, and start to run the reactor, the running cycle is 3-7 min of influent, 200-205 min of aeration, 10-20 min of sedimentation, 3-7 min of effluent, 5-15 min of idling, and 50-60% of effluent ratio, the influent uses simulated wastewater, wherein NH4 + -N concentration is 50-60 mg / L, PO4 3- -P concentration is 10-15 mg / L, and COD concentration is 800-1100 mg / L, and the aerobic granular sludge is obtained after 30-35 days of culture;

[0014] (2) Then, the wastewater is introduced into the sequencing batch reactor, and the reactor is run, the running cycle is 3-7 min of influent, 200-205 min of aeration, 10-20 min of sedimentation, 3-7 min of effluent, 5-15 min of idling, and 50-60% of effluent ratio, the effluent is introduced into the MBR reactor, wherein the membrane assembly is run in the intermittent negative pressure suction effluent mode, 6-8 min of suction and 1-2 min of stop suction;

[0015] (3) Finally, the effluent of the MBR reactor is subjected to micro-nano ozone disinfection treatment; the micro-nano ozone is generated by a micro-nano aerator, the particle size of the micro-nano ozone bubbles is 1-100 μm, and the volume of the micro-nano ozone to the volume of the effluent of the MBR reactor is 1:9.

[0016] Further, the sludge is the activated sludge in the aerobic tank of the A / O process. 2 / O process aerobic tank.

[0017] Further, the MLSS of the inoculated sludge is 4-5 g / L.

[0018] Further, the volume of the inoculated sludge is 40-50% of the effective volume of the sequencing batch reactor.

[0019] Further, the wastewater is the wastewater containing cosmetic products; specifically, the wastewater containing benzophenone-3, arbutin, kojic acid, tranexamic acid and 4-methoxysalicylic acid potassium.

[0020] Further, the bubble particle size in the aeration process is 1-3 mm, and the aeration amount is 1-3 L / min.

[0021] Further, the particle size of the aerobic granular sludge is 0.3-0.6 mm.

[0022] Beneficial effects

[0023] (1) The present application combines the characteristics of AGS, MBR, micro-nano ozone disinfection three processes, has excellent simultaneous denitrification and phosphorus removal efficiency, strong anti-shock load capacity, reduces membrane pollution, good sterilization effect, no secondary pollution, improves energy utilization efficiency and other advantages. Can effectively solve the problems of incomplete removal of refractory organic matter, incomplete disinfection, secondary pollution and high operation cost in the process of whole cosmetic wastewater treatment.

[0024] (2) In the process of the present application, AGS-MBR shows excellent COD, nitrogen and phosphorus removal efficiency, the average removal efficiency of COD is between 99.34±0.37%, the average removal rate of ammonia nitrogen reaches 99.55±0.41%, AGS-MBR shows excellent removal efficiency, the average removal rate of phosphorus reaches 95.83±1.76%, and AGS-MBR also has good membrane pollution control capacity. Compared with micro-aeration, the O3 escape rate is significantly reduced under micro-nano aeration mode, and the existence form of MNBs can also accelerate the decomposition of O3, which helps to improve the mass transfer efficiency. In addition, O3-MNBs also show stronger disinfection effect than O3-MBs of the same concentration. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is AGS-MBR reaction device diagram; wherein, 1, water distribution tank; 2, peristaltic pump; 3, water outlet electromagnetic valve; 4, membrane separation device; 5, riser; 6, downcomer; 7, aeration pump; 8, gas flow meter; 9, aeration head; 10, sampling port; 11, microcomputer time control switch; 12, constant temperature water tank; 13, constant temperature water circulating pump; 14, constant temperature circulating water insulation layer; 15, PH / dissolved oxygen measuring instrument (model ph / oxi 340i); 16, pH probe; 17, DO probe.

[0026] Figure 2 It is a micro-nano ozone device connection schematic diagram.

[0027] Figure 3 It is the removal efficiency of pollutants when AGS-MBR is stably operated; wherein, Figure 3 (a) is the removal efficiency of COD, Figure 3 (b) is the removal efficiency of NH4 + -N, Figure 3 (c) is the removal efficiency of PO4 3- -P.

[0028] Figure 4 It is the degradation law and removal effect of Arbutin and Kojic Acid by AGS-MBR combined process; wherein, Figure 4 (a) is the degradation law and removal effect of Arbutin, Figure 4(b) is the degradation law and removal effect of Kojic Acid.

[0029] Figure 5 is the removal efficiency of AGS to pollutants; wherein, Figure 5 a is the removal efficiency of COD, Figure 5 b is the removal efficiency of NH4 + -N, Figure 5 c is the removal efficiency of PO4 3- -P.

[0030] Figure 6 is the degradation law and removal effect of AGS process to Arbutin and Kojic Acid; wherein, Figure 6 (a) is the degradation law and removal effect of Arbutin, Figure 6 (b) is the degradation law and removal effect of Kojic Acid.

[0031] Figure 7 is the disinfection effect of O3-MNBs solution; Figure 7 (a) is the inactivation effect on E. coli, Figure 7 (b) is the O3 decay curve.

[0032] Figure 8 is the gas dispersion experiment reactor of O3-MNBs.

[0033] Figure 9 is the mechanism of micro-nano ozone bubble solution generating ·OH.

[0034] Figure 10 is the dispersion degree of O3 under two aeration modes; Figure 10 (a) is the gas phase concentration 16.11 mg / L, Figure 10 (b) is the gas phase concentration 60.60 mg / L.

[0035] Figure 11 is the O3 dissolution and decay curve under two aeration modes.

[0036] Figure 12 is the ·OH concentration under two aeration modes. DETAILED DESCRIPTION

[0037] The AGS-MBR reaction device in the application is shown in the schematic diagram as Figure 1 shown. The AGS-MBR reaction device is composed of an aerobic granular sludge reactor and an MBR reactor, which are coupled in a split type, are separately arranged and are connected through a pipeline.

[0038] The aerobic granular sludge reactor adopts a cylindrical sequencing batch reactor (SBR) with an effective volume of 4 L. An aeration head 9 is arranged at the bottom of the reactor, and an aeration pump 7 is used to aerate the ascending pipe 5 inside the reactor. The diameter of the bubbles generated is about 2 mm. A gas flow meter 8 is arranged on the pipeline connecting the aeration pump 7 and the aeration head 9, and the aeration amount is controlled to be 1-3 L / min. The ascending pipe 5 is arranged inside the descending pipe 6, and a pH probe 16 and a DO probe 17 are arranged at the top of the descending pipe 6. The probes are connected to a PH / dissolved oxygen meter 15 through a circuit. A constant-temperature circulating water insulation layer 14 is arranged outside the reactor. The bottom of the constant-temperature circulating water insulation layer 14 is provided with a water inlet, and the top is provided with a water outlet. A constant-temperature water tank 12 is used to input constant-temperature water into the insulation layer through the water inlet by a constant-temperature water circulating pump 13, and the constant-temperature water output from the water outlet is returned to the constant-temperature water tank 12 for heating.

[0039] A pipeline connected to a membrane separation device 4 is arranged in the middle of the aerobic granular sludge reactor, and a water outlet electromagnetic valve 3 is arranged on the pipeline. The membrane separation device 4 adopts an integrated MBR, and the membrane assembly is selected from polyvinylidene fluoride (PVDF) hollow fiber microfiltration membranes.

[0040] The influent enters the sequencing batch reactor through a peristaltic pump 2, and inoculated sludge is arranged in the sequencing batch reactor. The inoculated sludge is taken from a wastewater treatment plant A in Wuxi 2 The activated sludge in the aerobic tank of the O process is used as the inoculated sludge, the MLSS of the inoculated sludge is 5.0 g / L, the inoculated sludge volume is 2 L, and then a time control switch is used to control the state of each stage of the reactor. One operation cycle is 4 h, including 5 min of influent, 205 min of aeration, 15 min of sedimentation, 5 min of effluent, and 10 min of idling. The effluent ratio is 60%. The influent is artificial simulated wastewater, and the concentrations of NH4 + -N, PO4 3- -P and COD in the simulated wastewater are 56.70±3.84, 13.21±0.83, and 948.82±96.66 mg / L, respectively. After 30 days of cultivation of the reactor, completely granulated aerobic granular sludge can be obtained, and the obtained sludge has a round and regular shape, and the average particle size is 0.3-0.6 mm.

[0041] After the wastewater treatment starts, the influent enters the sequencing batch reactor through the peristaltic pump 2. Under the cycle mode of influent-aeration-idling- effluent, the aerobic granular sludge removes most of the organic matter and nitrogen and phosphorus in the wastewater, and then the SBR effluent enters the MBR reactor for further filtration and purification of water quality. The intermittent negative pressure suction effluent mode is used in the MBR reactor, and the suction time is 8 min and the stop suction time is 2 min.

[0042] The effluent of the MBR reactor enters the micro-nano ozone (O3-MNBs) aeration device for disinfection treatment. The micro-nano ozone aeration device is as shown in Figure 2As shown, ozone and effluent enter the micro-nano aerator pipeline, where they are fully mixed at the maximum gas-liquid ratio to produce an O3-MNBs mother liquor for disinfection. When the micro-nano aeration unit aerates the mother liquor, the air intake is controlled by a mass flow meter, and the ozone generator is set to 50%.

[0043] Example 1: Operation and decontamination performance of AGS-MBR section

[0044] After initial treatment of the influent by cultivating mature AGS in a sequencing batch reactor (SBR), the SBR effluent was filtered through a membrane assembly. The split AGS-MBR system independently controls the operating conditions in both reactors, which facilitates the cultivation and stabilization of AGS. When the reactor's mixed liquor DO is 4 mg / L and the influent C / N ratio is 10-15, the AGS-MBR demonstrates excellent simultaneous nitrogen, phosphorus, and organic matter removal. Therefore, based on analysis of influencing factors from previous experiments, adjustments were made and long-term operation trials were conducted under optimal operating conditions. The influent water quality is shown in Table 1.

[0045] Table 1 Raw water quality at each stage

[0046]

[0047] The removal effect of organic matter by AGS-MBR combination process, such as Figure 3 As shown in (a), during the 120-day operation, the average COD concentration of the influent varied between 844.47±30.01 mg / L. Through the interception effect of the bioreactor and membrane components, the COD concentration of the effluent during the stable operation period was always below 20 mg / L, between 5.59±4.93 mg / L, and the average COD removal efficiency was between 99.34±0.37%, indicating that the AGS-MBR device has an excellent COD removal effect. Figure 3 (a) As can be seen, the AG-MBR maintained a very stable organic matter removal efficiency over the 120-day operation period. Furthermore, the membrane tank retention rate reached 92.92 ± 5.42% during stable operation. Therefore, COD removal in the AGS-MBR is achieved by the microorganisms in the aerobic granular sludge and the enhanced organic matter retention and filtration by the membrane.

[0048] AGS-MBR can show excellent ammonia nitrogen removal efficiency through biodegradation. Figure 3(b) shows that although the ammonia nitrogen concentration of raw water fluctuated in the range of 55-65 mg / L (average 56.97 ± 4.05 mg / L), the ammonia nitrogen concentration in the AGS-MBR effluent was only 0.25 ± 0.23 mg / L, and the average removal rate of ammonia nitrogen by AGS-MBR reached 99.55 ± 0.41%. Through mechanism analysis, it is considered that the AGS-MBR system realizes the denitrification process through multiple pathways, and the efficient denitrification performance is the result of the combined action of the denitrification and short-range nitrification of microorganisms in the aerobic granular sludge, simultaneous nitrification and denitrification, and certain membrane filtration.

[0049] After a period of cultivation and acclimation, it can be seen from the results that the AGS-MBR shows excellent phosphorus removal efficiency. As shown in Figure 3 (c), although the PO4 3- -P concentration of raw water fluctuated in the range of 9-13 mg / L (average 11.75 ± 0.96 mg / L), the PO4 3- -P concentration in the AGS-MBR effluent was only 0.49 ± 0.22 mg / L, and the average removal rate of PO4 3- -P by AGS-MBR reached 95.83 ± 1.76%. Analysis shows that in addition to the assimilation during microbial growth, the phosphorus removal in the system is mainly achieved through the following pathways: phosphorus removal by aerobic phosphorus accumulating bacteria, phosphorus removal by denitrifying phosphorus accumulating bacteria, EPS adsorption, and phosphorus interception by the membrane. And because the membrane replaces the secondary sedimentation tank, it reduces the risk of collapse of the entire denitrification and phosphorus removal system due to sludge bulking, and enhances the stability of the system.

[0050] Example 2: Treatment effect of AGS-MBR on arbutin and kojic acid

[0051] Arbutin and kojic acid are the main whitening active ingredients in cosmetic surgery. Arbutin is easily soluble in water, difficult to biodegrade, and high concentration can inhibit microorganisms. It is easily hydrolyzed into hydroquinone (carcinogenic and sensitizing) under acidic or high temperature conditions. Kojic acid is easily soluble in water and ethanol, sensitive to light and heat, and strongly acidic (pH 3-4), and needs to be treated after neutralization.

[0052] 5 mg / L Arbutin and 10 mg / L Kojic Acid were added to the AGS-MBR combined process to explore the removal effect of the AGS-MBR combined process on new pollutants. Figure 4 The degradation law and removal effect of AGS-MBR combined process on Arbutin and Kojic Acid are shown. Arbutin is a hydrophilic high molecular organic substance, which is difficult to adsorb on AGS, resulting in poor removal effect in the early stage, such as Figure 4(a) shows. But with the increase of stress time and the MBR membrane can intercept the undegraded arbutin and its intermediates, the removal rate of arbutin gradually increased from the initial 16% to 84% and remained stable, indicating that the process of the application has a higher removal rate of arbutin. From Figure 4 (b) can be seen that the removal effect of Kojic Acid is poor in the early stage, which may be due to the inhibition of Kojic Acid on the activity of related functional microorganisms. But long-term drug stress makes the removal rate of Kojic Acid gradually increase from the initial 10% to 80% and remain stable, indicating that the process of the application also has good removal effect on Kojic Acid.

[0053] Comparative Example 1

[0054] In order to compare the removal effect of AGS and AGS-MBR combined process on conventional pollutants and new pollutants, the same aerobic granular sludge under the same cultivation mode was used to treat the same water quality (without adding arbutin and kojic acid) in Example 2. The removal effect of AGS process on COD is shown in Figure 5 a, the removal rate of COD is low in the early stage of reactor operation, and maintains at about 80%. With the continuous growth of sludge biomass, the removal rate of COD gradually increases, and the removal rate can reach more than 85%. When the system is stably operated, the COD removal rate can be stably maintained at about 85%, and the effluent COD is lower than 50 mg / L, but it is significantly lower than the removal efficiency of AGS-MBR combined process on COD (99.34±0.37%). The removal effect of AGS process on NH4 + -N is shown in Figure 5 b, the removal rate of ammonia nitrogen maintains at about 60% and has large fluctuation in the early stage of reactor operation, and the ammonia nitrogen removal efficiency is low. With the increase of biomass, the removal rate of ammonia nitrogen gradually increases, and finally can reach about 90%. The effluent ammonia nitrogen concentration maintains at about 5 mg / L. Compared with the stable growth of COD removal rate, the ammonia nitrogen removal rate has large fluctuation in the growth process, but it is slightly lower than the average removal rate of AGS-MBR combined process on ammonia nitrogen (99.55±0.41%). The removal effect of AGS process on PO4 3- -P is shown in Figure 5 c, the phosphorus removal effect is poor in the early stage, and the phosphorus removal efficiency gradually improves after the reactor is operated for 30 days, and the removal rate can reach more than 50%. With the strict control of SRT in the reactor during the operation process, the reactor is regularly discharged, and the removal effect of phosphate is further improved, which can be close to 80%. But it is still significantly lower than the removal effect of AGS-MBR combined process on PO4 3-The average removal rate of -P was (95.83±1.76%). It can be seen that compared with the single AGS process, the AGS-MBR combined process has significant advantages in removing conventional pollutants in wastewater.

[0055] Comparative Example 2

[0056] 5 mg / L Arbutin and 10 mg / L Kojic Acid were added to the AGS process in Comparative Example 1 to explore the removal effect of AGS on refractory pollutants and compare it with the AGS-MBR combined process. Figure 6 The figure shows the degradation patterns and removal efficiency of arbutin and kojic acid using the AGS process. As can be seen, the AGS process achieves maximum removal rates of 66% and 69%, respectively, lower than those achieved by the AGS-MBR combined process, and the removal efficiency is relatively unstable. This demonstrates that the AGS-MBR combined process significantly outperforms AGS alone in terms of both removal efficiency and stability for both conventional and emerging pollutants.

[0057] Example 3: Operation and disinfection effect of micro-nano ozone

[0058] The micro-nano aeration technology is coupled with O3 disinfection to form O3-MNBs. The O3-MNBs experimental device is as follows: Figure 2 During the experiment, ozone and experimental water were mixed and introduced into the micro-nano aerator pipeline. The mixture was then thoroughly mixed at the maximum gas-liquid ratio (1:9) to prepare the O3-MNBs mother solution. The micro-nano aeration system maintained the same air flow rate as the microporous aeration system, maintaining a stable 100 mL / min. The ozone generator was set to 50%. During the disinfection experiments, the O3-MNBs mother solution was diluted in a gradient to produce solutions with varying O3 concentrations.

[0059] In order to verify the actual oxidation effect of O3 under micro-nano aeration mode, Escherichia coli (E. coli) was used as the research object. The inactivation ability results were shown in Table 1. Figure 7 (a). As shown in the figure, when no O3 is dissolved, MNBs still have a certain inactivation ability, and can inactivate up to 1.25lg. After 10 minutes, the inactivation ability of MNBs is about half of that after 30 minutes. Compared with the O3 solution with a concentration of 0 mg / L, the inactivation rate of O3-MNBs with different concentrations is significantly different. In the experiment, the higher the O3 concentration is within the range of 0.5-2.5 mg / L, the higher the O3 concentration is. 3- The faster the MNBs respond to E. coli inactivation, the better the sterilization effect. As shown in the figure, when the O3 concentration is 2.5mg / L, the micro-nano aeration method can quickly inactivate 9log 10High concentration of bacteria solution (CFU / mL) was completely sterilized in 1 min, and the reaction was rapid.

[0060] The consumption of O3 in the disinfection process is shown in Figure 7 (b). O3 in O3-MNBs showed a significant faster consumption in the disinfection process, because the continuous pressurization of MNBs in the shrinkage process could continuously enhance the mass transfer efficiency at the gas-liquid interface, promote the decomposition of O3 to produce ·OH, and have a remarkable effect on inactivating microorganisms and removing organic pollutants. The O3 in 1.0 mg / L O3-MNBs solution decayed rapidly, and the O3 depletion rate was consistent with the rate of complete inactivation of E. coli, indicating that the form of O3-MNBs could more fully exert the oxidative disinfection capacity of O3. In 0.5 mg / L O3-MNBs solution, the faster sterilization response speed at the initial stage of disinfection was also related to the high mass transfer and consumption of O3. The pressurization and shrinkage of micro-nano bubbles in the solution would produce ·OH, and had a synergistic effect with O3 decomposition, accelerating the disinfection process. The half-life of O3 in each group was not more than 5 min, and the O3 concentration in the solution was lower, which was reduced to 0 mg / L faster. Because the initial dosage of the same bacterial concentration was not enough for the oxidation of cells, the residual disinfectant concentration at the initial stage of disinfection was already greatly reduced, and the initial O3 concentration was not enough to inactivate all microorganisms. The "Outdoor Water Supply Design Standard" stipulates that the dosage of O3 for disinfection should be 1-2 mg / L. O3 in O3-MBs solution was consumed slowly, and ·OH was produced less. Even if O3 in O3-MNBs was depleted, ·OH could still be produced significantly, and this strong oxidizing substance was particularly important for ensuring the continuous disinfection capacity.

[0061] Example 4: Optimization of ozone micro-nano bubble characteristics

[0062] The closed reactor (O3-MNBs) designed and customized for micro-nano bubble aeration is as follows Figure 8The reactor top and the tank body were connected by hex head bolts, flanges and butterfly nuts. The inner diameter and height of the cylindrical tank body were 100 mm, and the wall thickness was 10 mm. The reactor top gas outlet was fixed with an elbow pagoda, connected with a Φ8x10 mm polytetrafluoroethylene hose. Its top had another hole sealed with a four-part double outer thread joint, the upper end of which was connected with the water inlet pipe of the micro-nano aerator, and the lower end was connected with a variable diameter pagoda to extend the polytetrafluoroethylene pipe; a hole was sealed with a four-part outer upper and inner lower thread joint, the upper end of which was connected with the water outlet pipe of the micro-nano aerator, and the lower end was connected with the micro-nano aerator. The water outlet was connected with the micro-nano aerator. The gas inlet amount of O3-MNBs was controlled by a mass flowmeter at 50 mL / min, the gas inlet amount of the ozone generator was 100 mL / min, and the ozone generator was adjusted to 10% and 50% in the low and high gas inlet amount groups, respectively. The reactor tank was filled with 2.5 L of water. By measuring the O3 concentration in the tail gas absorption bottle, the residual BKI absorption liquid volume in the bottle was calculated, and the cumulative O3 emission amount was calculated. Then, by comparing the cumulative gas inlet amount, the O3 emission rate was calculated.

[0063] When the O3 gas inlet amount of the reactor was controlled at 0.81 mg / min, the calculated cumulative O3 emission amount of O3-MNBs was less than 0.01 mg, and the BKI solution was not obviously oxidized within 30 min by naked eye observation, and the solution remained transparent. By adjusting the ozone generator shift, the gas inlet and outlet amount of the ozone generator remained unchanged, and when the gas inlet amount of the ozone generator was stable at 3.03 mg / min, the O3 generation concentration at the outlet of the ozone generator increased from 16.11 mg / L to 60.60 mg / L. After 5 min, the cumulative emission amount caused by micro-nano aeration was still less than 0.03 mg, and after 10 min, O3-MNBs showed visible O3 emission, with an emission rate of 7.16%, indicating that micro-nano aeration had good effect in preventing O3 emission. In addition, 5 mg / min O3 was uniformly added to O3-MNBs within 10 min, and no aeration measures were taken for the subsequent 30 min, and continuous stirring was found. Micro-nano aeration allowed O3 to dissolve quickly into water, which may be due to the fact that micro-nano bubbles remained in water for a long time, gradually shrinking, increasing the specific surface area, and increasing the water surface tension, thereby allowing more gas to pass through the bubble interface and dissolve into water.

[0064] The initiation step of O3 in acidic and alkaline solutions to generate ·OH is different, and formula (1) briefly describes the general initiation reaction process. Nohemi et al. found that the cumulative ·OH generated by the combination of H2O2 and O3 and ultrasonic treatment was almost twice that of H2O2 alone by detecting the product of ·OH and terephthalic acid, hydroxyl terephthalic acid. The ability of O3 to generate ·OH is outstanding.

[0065] 3O3+H2O→4O2+2HO· (1)

[0066] Figure 9 Four mechanisms of ·OH production in O3-MNBs solution are described as follows:

[0067] (1) During the mass transfer of MNBs wrapped with O3 molecules, O3 escapes from the bubble and reacts with water to produce ·OH, as shown in equation (1);

[0068] (2) O3 molecules in the solution directly react with water to produce ·OH according to equation (1);

[0069] (3) When MNBs shrink, the internal pressure increases to the limit and the bubble bursts (the dashed line represents the outline before the bubble bursts), the gas-liquid interface disappears, and at the same time, the ultra-high chemical energy is released instantaneously, triggering the production of ·OH; Figure 9

[0070] (4) During the shrinking process of MNBs, O3 molecules are adsorbed, and the bursting of MNBs and the decomposition reaction of O3 are synergistically promoted to produce a large amount of ·OH.

[0071] Comparative Example 3

[0072] Figure 10 The degree of O3 loss in the micro-nano aeration (O3-MNBs) and ordinary aeration (O3-MBs) modes is shown. When the O3 concentration of the reactor is low, the O3 dispersion in the O3-MNBs and O3-MBs modes is shown in Figure 10 (a), and the O3 input is 0.81 mg / min. The cumulative dispersion of O3 in the O3-MNBs group is less than 0.01 mg, and the BKI solution is observed to be transparent within 30 min. In the O3-MBs group, the BKI solution in the tail gas absorption bottle starts to discolor significantly at 2 min, and a large amount of yellow I2 is generated, indicating that O3 is lost seriously. The cumulative dispersion of O3 is 0.04 mg at 2.5 min, the loss reaches 0.38 mg O3 at 5 min, the dispersion rate is 9.42%, and the cumulative loss of O3 is 35.19% at 15 min, and the cumulative dispersion is 4.25 mg. By comparing the ordinary aeration disc and the micro-nano bubble, it is found that the dispersion rate of the latter is only 0.8% at 70 min, while the dispersion rate of the ordinary aeration disc reaches 70% when 10 mg / L O3 is added at 32.91 mg / min into 700 L water. Therefore, the micro-nano aeration method has better effect in preventing O3 dispersion.

[0073] ​To investigate the effect of O3 dosage concentration on the escape rate, the air inlet and outlet of the ozone generator were controlled to be constant, and the O3 generation concentration at the outlet of the ozone generator was increased from 16.11 mg / L to 60.60 mg / L when the O3 amount of the air inlet of the escape experiment reactor was stable at 3.03 mg / min. The O3 escape conditions are shown in Figure 10 Fig. 2(a) and (b). Under the ordinary micro-porous aeration mode, the solution in the tail gas absorption bottle began to turn yellow at about 2 min. After 5 min, the cumulative escape amount of the O3-MBs group exceeded 1.93 mg, and the escape rate was 12.76%, while the cumulative escape amount caused by the micro-nano aeration mode was still less than 0.03 mg. Subsequently, the O3 escape phenomenon was observed in the O3-MNBs group, and the escape rate was 7.16% at 10 min. The escape rate of the O3-MBs group was about 22.49% at this time. The escape rate of the O3-MNBs group reached 23.81% at 15 min, but it was still 12.55% lower than that of the O3-MBs group at 15 min, and the cumulative escape amount was 5.71 mg less. Figure 10 (a) and (b) show that as the O3 dosage concentration increases, O3 will also escape significantly under the micro-nano aeration mode. However, the effect of the micro-nano aeration mode in preventing O3 escape loss is still better than that of the micro-porous aeration mode.

[0074] To investigate the O3 dissolution and decay characteristics under the micro-nano aeration and micro-porous aeration modes, 5 mg / min O3 was uniformly added to the O3-MNBs group and the O3-MBs group within 10 min, and no aeration measures were taken for the subsequent 30 min with continuous stirring. The O3 dissolution and decay curves under the micro-nano aeration and micro-porous aeration modes are shown in Figure 11 Fig. 3(a) and (b). As shown in the figure, the O3 concentration of the O3-MNBs (1.68 mg / L) was about twice that of the O3-MBs (0.81 mg / L) at 1 min of aeration. The O3 dissolution concentration of the O3-MNBs was 7.75 mg / L when the aeration was stopped, which was 1.41 mg / L higher than that under the micro-porous aeration mode, and the cumulative loss of O3 added within 10 min was 18.07 mg less. The half-life of O3 in pure water is 8-20 min. After stopping aeration, the O3 concentration of the O3-MNBs group was lower than that of the O3-MBs group within 5 min, indicating that the accelerated decomposition of O3 may be caused by the form of micro-nano bubbles. After 10 min of micro-nano aeration with high-purity air and 1 day of degassing, O3 was introduced into the O3-MNBs group under the micro-porous aeration mode, Figure 11 ​The results of Air-MNBs / O3-MBs group show that the micro-porous aeration cannot promote the dissolution of O3 when there are micro-nano bubbles in the water, which means that the dissolution rate is less than the decomposition rate of O3 at this time, further verifying the guess that micro-nano bubbles promote the decomposition of O3. The O3 dissolution amount of O3-MNBs group is much higher than that of Air-MNBs / O3-MBs group when the normal micro-nano aeration is used, because the dissolution rate promoted by the micro-nano aeration is higher than the decomposition rate, and the self-pressurization characteristics of the micro-nano bubbles during the shrinkage process make the mass transfer process continue through the micro-nano bubbles even if the gas content in the water has reached the supersaturation condition, which helps to maintain efficient mass transfer.

[0075] After adding excess 4-HBA, the ·OH produced by O3 in the solution is immediately captured by 4-HBA, and part of O3 is also consumed by 4-HBA and its hydroxylated product 3,4-dHBA, resulting in a lower O3 dissolution concentration than that during normal dissolution during the aeration process, as shown by the dashed line in FIG. 6. However, the O3 concentration of the O3-MNBs / 4-HBA group at the end of aeration is still higher than that of the O3-MBs / 4-HBA group, indicating that the dissolution rate of O3 is still higher than the decomposition and consumption rate at this time, and the dissolution is better than the micro-porous aeration method. Figure 6

[0076] Figure 12 It is shown that the ·OH production ability is different under the two aeration methods, and it is known from the figure that micro-nano aeration has obvious advantages. Within 10 min of O3 input, the ·OH production rate of the O3-MBs group is 7.61 μM / min (R 2 ≈0.997), and that of the O3-MNBs group is 75% higher, reaching 13.25 μM / min (R 2 ≈0.952), and the highest concentration is 108.36 μM. This is not only due to the higher O3 dissolution concentration brought by the micro-nano aeration method, but also possibly due to the increase in internal pressure during the gradual shrinkage of the micro-nano bubbles, reaching the limit and causing the violent change of the disappearance of the gas-liquid interface, which makes the accumulated chemical energy of the gathered high-concentration positive and negative ions release at once, triggering the generation of a large amount of ·OH. The results of the Air-MNBs group also verify this hypothesis, and the micro-nano aeration method still produces ·OH in water when only high-purity air is added, with a production rate of 0.14 μM / min (R 2 ≈0.970), which confirms that micro-nano bubbles can also produce ·OH obviously without relying on the decomposition of O3. In addition, the ·OH production rate of the O3-MNBs group is about 1.7 times that of the sum of the Air-MNBs group and the O3-MBs group, indicating that the micro-nano bubble burst and the O3 decomposition reaction also have a synergistic mechanism for producing ·OH.

[0077] ​After 10 min of aeration, the O3-MNBs group still had ·OH generation (0.64 μΜ / min, R 2 ≈0.928). The burst of micro-nano bubbles in the Air-MNBs group also continued to trigger the generation of ·OH (0.13 μΜ / min, R 2 ≈0.992), which was close to the ·OH generation rate when it was aerated, indicating that the burst of micro-nano bubbles still had a strong effect on the generation of ·OH without an external gas source. Therefore, based on the characteristics of micro-nano bubbles generating free radicals, O3-MNBs had a persistent oxidative disinfection capacity, which was more advantageous than ultraviolet disinfection.

[0078] and the change in O3 concentration after 20 min of stirring Figure 11 At this time, the O3 concentration of the O3-MNBs / 4-HBA group was close to that of the O3-MBs / 4-HBA group, but the ·OH generation rate of the O3-MNBs / 4-HBA group was higher than that of the O3-MBs / 4-HBA group Figure 12 It can be seen that the difference in the ·OH generation rate between the two groups was greater than the ·OH generation rate of the Air-MNBs group, further indicating that without an external gas source, micro-nano bubbles still had the phenomenon of promoting the generation of ·OH by combining with O3 decomposition. In contrast, the O3-MBs group almost did not generate ·OH after no longer adding O3, which was due to its large diameter, according to the Stokes equation, the rising speed in water was too fast, so the residence time was short, there was no process of bubble shrinkage and internal pressurization, so it lacked the role of bubble rupture alone to trigger the generation of ·OH and promote the generation of ·OH by O3 decomposition.

[0079] The above provided examples are not intended to limit the scope encompassed by the present application, and the described steps are not intended to limit the execution order thereof. Those skilled in the art make obvious improvements to the present application in combination with existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. A method for treating cosmetic wastewater, characterized in that: The method is carried out using an AGS-MBR reactor; the AGS-MBR reactor consists of an aerobic granular sludge reactor and an MBR reactor, which are placed separately and the water outlet of the aerobic granular sludge reactor is connected to the water inlet of the MBR reactor through a pipeline; The aerobic granular sludge reactor is a cylindrical sequencing batch reactor, with an aeration device at the bottom of the reactor, and the aeration device adopts a common aeration head; the MBR reactor is an integrated MBR reactor, wherein the membrane component adopts a hollow fiber microfiltration membrane of polyvinylidene fluoride; The method comprises the following steps: (1) Sludge was inoculated into the sequencing batch reactor and the reactor was started. The operation cycle was 3-7 minutes of water inlet, 200-205 minutes of aeration, 10-20 minutes of sedimentation, 3-7 minutes of drainage, and 5-15 minutes of idle time. The drainage ratio was 50-60%. The inlet water used was simulated wastewater, of which NH4 + -N concentration is 50~60mg / L, PO4 3- -P concentration is 10-15 mg / L, COD concentration is 800-1100 mg / L, and aerobic granular sludge is obtained after 30-35 days of cultivation; (2) Then, wastewater is introduced into the sequencing batch reactor, and the reactor is operated with an operation cycle of 3-7 minutes of water inlet, 200-205 minutes of aeration, 10-20 minutes of sedimentation, 3-7 minutes of drainage, 5-15 minutes of idle time, and a drainage ratio of 50-60%. The effluent is introduced into the MBR reactor, wherein the membrane module is operated by intermittent negative pressure suction water outlet mode, suction for 6-8 minutes, and stop suction for 1-2 minutes; (3) Finally, the effluent from the MBR reactor is disinfected with micro-nano ozone; the micro-nano ozone is generated by a micro-nano aerator; the volume of the micro-nano ozone and the volume of the effluent from the MBR reactor are 1:

9.

2. The method according to claim 1, wherein Sludge from sewage plant A 2 / O process aerobic tank activated sludge.

3. The method according to claim 1, wherein The MLSS of the inoculated sludge is 4-5 g / L; the sludge inoculation volume is 40-50% of the effective volume of the sequencing batch reactor.

4. The method according to claim 1, wherein The particle size of aerobic granular sludge is 0.3-0.6mm.

5. The method according to claim 1, wherein The sewage is wastewater containing cosmetics.

6. The method according to claim 1, wherein During the aeration process, the bubble particle size is 1 to 3 mm, and the aeration volume is 1 to 3 L / min.

7. The method according to claim 1, wherein The particle size of micro-nano ozone bubbles is 1 to 100 μm.

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