Activated sludge suitable for polymer-containing sewage, preparation method thereof and sewage treatment method

Abstract

The invention provides activated sludge suitable for polymer-containing sewage, a preparation method of the activated sludge and a sewage treatment method. The preparation method comprises the following steps: sequentially carrying out first treatment, standing layering and supernate removal on a first sewage mixture by using initial activated sludge, completing one cycle in first incubation, carrying out one or more cycles in the first incubation until the COD removal rate of the initial activated sludge reaches 50-70%, obtaining the first activated sludge, and carrying out second incubation; the second incubation comprises the following steps: carrying out second treatment on the second sewage mixture by utilizing the first activated sludge, standing for layering and removing supernate, and completing primary circulation in the second incubation to obtain second activated sludge; the second incubation cycle is performed once or multiple times until the sewage COD removal rate of the second activated sludge reaches the highest level and is stable, and the activated sludge suitable for the polymer-containing sewage is obtained. The method can solve the problem that polymer-containing sewage with low polymer concentration is difficult to treat in the prior art, and is suitable for the field of sewage treatment.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and more particularly to an activated sludge adapted to polymer-containing sewage, a preparation method thereof, and a sewage treatment method. Background Art

[0002] At present, the average comprehensive water content of oil production fluids has exceeded 80%. A large amount of oily sewage is generated during the production process. The composition of this produced water is complex. In addition to natural impurities such as soluble salts, heavy metals, suspended emulsified oil, and solid particles, it also contains some chemical additives used to change the properties of the produced water, as well as acids, deoxidizers, lubricants, bactericides, scale inhibitors, etc. injected into the formation. In recent years, with the popularization and application of tertiary oil recovery technologies such as polymer flooding, the produced fluids also contain polymers, surfactants, and other chemicals. If the re-injection method is still used for treatment, it is easy to cause formation plugging, accelerate pipeline corrosion, and emissions will cause environmental pollution. Therefore, certain treatment must be carried out before re-injection or discharge. In water pollution control, the aerobic activated sludge method is a method with remarkable effects, and its promotion and application value is relatively high. It can remove pollutants more thoroughly than other methods.

[0003] The aerobic activated sludge method uses the existing activated sludge as the main part and aerobic bacteria to decompose the organic matter in the sewage, thereby achieving the treatment of pollutants. In the prior art, such existing activated sludge is usually obtained in a sludge pond and incubated briefly with oily sewage. When using this activated sludge to treat polymer-containing sewage, although it can reduce the polymer concentration in polymer-containing sewage with a high polymer concentration to a certain extent, the treatment effect on polymer-containing sewage with a polymer concentration less than 10 mg / L is not good, and there is still a low concentration of polymer residue at the outlet. Summary of the Invention

[0004] The main object of the present invention is to provide an activated sludge adapted to polymer-containing sewage, a preparation method thereof, and a sewage treatment method to solve the problem in the prior art that it is difficult to treat polymer-containing sewage with a low concentration of polymer.

[0005] To achieve the above object, according to the first aspect of the present invention, a method for preparing activated sludge adapted to polymer-containing sewage is provided. The preparation method includes: using the initial activated sludge to perform a first treatment, static layering, and supernatant removal on the first sewage mixture in sequence to complete one cycle in the first incubation; the cycle in the first incubation includes one or more times until the COD removal rate of the initial activated sludge reaches 50-70%, obtaining the first activated sludge, and starting the second incubation; the second incubation includes: using the first activated sludge to perform a second treatment, static layering, and supernatant removal on the second sewage mixture in sequence to complete one cycle in the second incubation, obtaining the second activated sludge; the second incubation cycle is performed one or more times until the sewage COD removal rate of the second activated sludge reaches the highest level and stabilizes, obtaining the activated sludge adapted to polymer-containing sewage; wherein, during the first treatment and the second treatment, aeration disturbance is continuously carried out; both the first sewage mixture and the second sewage mixture include oily sewage and polymer-containing sewage; the volume ratio of the polymer-containing sewage in the second sewage mixture is greater than the volume ratio of the polymer-containing sewage in the first sewage mixture; in the first incubation and the second incubation, the volume ratio of the polymer-containing sewage in the sewage mixture used for each cycle remains unchanged or increases.

[0006] Further, in the first incubation and the second incubation, the pH of the initial activated sludge, the first activated sludge, and the second activated sludge is 7-8.5, and the temperature is 20-30°C; preferably, in each cycle of the first incubation and the second incubation, nutrient components are added to the sludge; preferably, the nutrient components include a carbon source, a nitrogen source, and a phosphorus source; preferably, the carbon source includes sucrose; preferably, the nitrogen source and the phosphorus source are inorganic salts, and the inorganic salts include diamine phosphate and urea; preferably, in the nutrient components, the mass ratio of C element: N element: P element is 100:5:1.

[0007] Further, in the second incubation, the influent COD, the effluent COD, and the activated sludge concentration are monitored. When the COD removal rate reaches 90%, the second incubation ends, and the activated sludge adapted to polymer-containing sewage is obtained.

[0008] Furthermore, the polymer-containing sewage includes polymers, petroleum hydrocarbons, and solid particle suspensions; preferably, the concentration of polymers in the polymer-containing sewage is 100-200 mg / L, the concentration of petroleum hydrocarbons is 10-300 mg / L, and the concentration of solid particle suspensions is 30-2000 mg / L; preferably, the polymers include any one or more of the following: polyacrylamide, polyvinyl alcohol, polystyrene, or polyurethane; preferably, the oil-containing sewage includes petroleum hydrocarbons and solid particle suspensions; preferably, the concentration of petroleum hydrocarbons in the oil-containing sewage is 100-500 mg / L, and the solid particle suspension is 30-2000 mg / L; preferably, in the first sewage mixture, the volume ratio of the oil-containing sewage to the polymer-containing sewage is (5-1):1; preferably, in the second sewage mixture, the volume ratio of the oil-containing sewage to the polymer-containing sewage is (3-1):1; preferably, in the last cycle of the second incubation, the volume ratio of the oil-containing sewage to the polymer-containing sewage is 1:1.

[0009] Furthermore, the volume ratio of the activated sludge to the first sewage mixture is 1:(8-10); preferably, the volume ratio of the activated sludge to the second sewage mixture is 1:(8-10).

[0010] Furthermore, the aeration volume of the aeration disturbance is 1-5 mg / L, and the aeration time is 20-23 h; preferably, the dissolved oxygen in the first incubation is 1-2 mg / L; preferably, the dissolved oxygen in the second incubation is 3-4 mg / L.

[0011] Furthermore, the time of both the first incubation and the second incubation is 22-24 h, and the static separation time is 25-45 min; preferably, the number of cycles of the first incubation is 1-5 times; preferably, the number of cycles of the second incubation is 1-10 times; preferably, each cycle in the first incubation and the second incubation takes 1 day.

[0012] To achieve the above object, according to the second aspect of the present invention, there is provided an activated sludge adapted to polymer-containing sewage prepared by the preparation method of any one of the above-mentioned activated sludges adapted to polymer-containing sewage.

[0013] To achieve the above object, according to the third aspect of the present invention, there is provided a water treatment method, which includes treating the polymer-containing sewage to be treated with the activated sludge prepared by the preparation method of any one of the above-mentioned activated sludges adapted to polymer-containing sewage; the concentration of polymers in the polymer-containing sewage to be treated is 0.1-1000 mg / L.

[0014] Further, the sewage treatment method includes: mixing activated sludge with polymer-containing sewage to be treated at a volume ratio of 1:(1-10), performing continuous aeration and agitation, controlling the dissolved oxygen at 4-5 mg / L and the pH at 7-8, operating for one cycle, where one cycle is 2-10 days; preferably, after operating for one cycle, standing for layering and removing the supernatant, adding new polymer-containing sewage to be treated for sewage treatment, and the activated sludge is used for a total of 5 cycles in the sewage treatment method.

[0015] Applying the technical solution of the present invention, using the above preparation method of activated sludge adapted to polymer-containing sewage, through the first incubation and the second incubation, the removal ability of the activated sludge for polymers in the polymer-containing sewage can be gradually improved. By domestication of the sludge, activated sludge adapted to polymer-containing sewage is obtained, so as to realize the treatment of polymer-containing sewage with low concentration of polymers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0017] Figure 1 It shows a schematic flow chart of treating sewage according to an embodiment of the present invention.

[0018] Figure 2 It shows a schematic diagram of the change of the 30-minute sedimentation ratio (SV) of activated sludge with the domestication time during the domestication process of activated sludge according to Embodiment 1 of the present invention.

[0019] Figure 3 It shows a schematic diagram of the change of the concentration of activated sludge (MLSS) and pH with the domestication time during the domestication process of activated sludge according to Embodiment 1 of the present invention.

[0020] Figure 4 It shows a schematic diagram of the change of influent COD, effluent COD and COD removal rate with the domestication time during the domestication process of activated sludge according to Embodiment 1 of the present invention.

[0021] Figure 5 It shows a schematic diagram of the change of effluent COD according to Embodiment 2 of the present invention.

[0022] Figure 6 It shows a schematic diagram of the change of effluent polymer concentration according to Embodiment 2 of the present invention.

[0023] Figure 7 It shows a schematic diagram of the change of oil content in the effluent according to Embodiment 2 of the present invention.

[0024] Figure 8Shows a schematic diagram of the change in the effluent COD according to Embodiment 3 of the present invention.

[0025] Figure 9 Shows a schematic diagram of the change in the effluent polymer concentration according to Embodiment 3 of the present invention.

[0026] Figure 10 Shows a schematic diagram of the change in the oil content in the effluent according to Embodiment 3 of the present invention.

[0027] Figure 11 Shows a schematic diagram of the change in the suspended solids content in the effluent according to Embodiment 3 of the present invention. Detailed implementation manners

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0029] Term explanation:

[0030] COD: Abbreviation for Chemical Oxygen Demand, which is an index used to measure the content or concentration of organic pollutants in water in sewage treatment.

[0031] MLSS: In sewage treatment, MLSS (Mixed Liquor Suspended Solids) refers to the total mass of suspended biological solids in the activated sludge, including the microorganisms, suspended sludge particles and other tiny solid particles existing in the activated sludge, that is, it represents the concentration of the activated sludge.

[0032] SVI: Sludge Volume Index is a parameter used to evaluate the sedimentation performance of activated sludge.

[0033] As mentioned in the background art, the biological treatment method in the prior art can only treat the polymer sewage containing high-concentration polymers, but it is difficult to effectively remove the polymer water with low polymer concentration, and there are still low-concentration polymer residues at the effluent. Therefore, in the present application, the inventor attempts to provide a new activated sludge suitable for polymer-containing sewage and its preparation method to treat the polymer-containing sewage with low polymer concentration, and thus a series of protection schemes of the present application are proposed.

[0034] In the first typical embodiment of the present application, a preparation method of activated sludge adapted to polymer-containing sewage is provided. The preparation method includes: using the initial activated sludge to perform a first treatment, static layering, and removal of the supernatant on the first sewage mixture in sequence to complete one cycle in the first incubation; the cycle in the first incubation includes one or more times until the COD removal rate of the initial activated sludge reaches 50-70%, including but not limited to 50%, 60%, or 70%, to obtain the first activated sludge and start the second incubation; the second incubation includes: using the first activated sludge to perform a second treatment, static layering, and removal of the supernatant on the second sewage mixture in sequence to complete one cycle in the second incubation to obtain the second activated sludge; the second incubation cycle is carried out one or more times until the sewage COD removal rate of the second activated sludge reaches the highest level and stabilizes to obtain the activated sludge adapted to polymer-containing sewage; wherein, during the first treatment and the second treatment, aeration disturbance is continuously carried out; both the first sewage mixture and the second sewage mixture include oily sewage and polymer-containing sewage; the volume ratio of the polymer-containing sewage in the second sewage mixture is greater than the volume ratio of the polymer-containing sewage in the first sewage mixture; in the first incubation and the second incubation, the volume ratio of the polymer-containing sewage in the sewage mixture used for each cycle remains unchanged or increases.

[0035] In the prior art, the activated sludge in the biological treatment method is usually briefly incubated with oily sewage, but the activated sludge cannot be successfully domesticated, and the finally obtained activated sludge has low activity. Although using such activated sludge can reduce the polymer concentration of polymer-containing sewage with a high polymer concentration to a certain extent, due to the limitation of activity, the treatment effect on polymer-containing sewage with a low polymer concentration is not good, and there are still many residues at the water outlet, and the COD removal rate effect is poor. The present application incubates and domesticates the activated sludge with high-concentration polymer-containing sewage, that is, performs the above-mentioned first incubation and second incubation. The polymer in the high-concentration polymer-containing sewage is a polymer with high carbon and high nitrogen content, which can provide sufficient carbon source and nitrogen source for aerobic bacteria, and at the same time can purify the water quality after consuming and decomposing the polymer. Using it to incubate the activated sludge can effectively domesticate the activated sludge. This method can not only turn the polymer-containing sewage into a useful resource, but also provide more efficient activated sludge and a method for treating oligomer-containing sewage for sewage treatment, and can more thoroughly remove oligomers, oily substances, and residues in the sewage.

[0036] In a preferred embodiment, during the first incubation and the second incubation, the pH values of the initial activated sludge, the first activated sludge, and the second activated sludge are all 7 - 8.5, including but not limited to 7, 7.5, 8, or 8.5, and the temperature is 20 - 30 °C, including but not limited to 20 °C, 23 °C, 24 °C, 24.5 °C, 25 °C, 25.5 °C, 26 °C, 27 °C, 28 °C, 29 °C, or 30 °C; preferably, during each cycle of the first incubation and the second incubation, nutrient components are added to the sludge; preferably, the nutrient components include a carbon source, a nitrogen source, and a phosphorus source; preferably, the carbon source includes sucrose; preferably, the nitrogen source and the phosphorus source are inorganic salts, and the inorganic salts include diamine phosphate and urea; preferably, in the nutrient components, the mass ratio of C element : N element : P element is 100 : 5 : 1.

[0037] During the incubation (acclimation) of activated sludge, the pH value has a direct impact on the growth and activity of microorganisms. Different microorganisms have different tolerances to changes in pH value. The suitable pH range for the activated sludge in this application is 7 - 8.5. When within this range, the microorganisms in the activated sludge of this application can maintain good activity and growth status.

[0038] If the temperature during the incubation process is too high, it will affect the concentration of dissolved oxygen, causing its concentration to decrease, and it will also lead to a decrease in the activity of the microbial enzymes in the activated sludge; if the temperature is too low, although the concentration of dissolved oxygen increases, as mentioned above, too high a concentration of dissolved oxygen will also affect the incubation effect, and low temperature will also lead to a decrease in the activity of the microbial enzymes in the activated sludge. Therefore, too high or too low a temperature will result in a poor acclimation effect and a decrease in the activity of the activated sludge.

[0039] In a preferred embodiment, during the second incubation, the influent COD, effluent COD, and activated sludge concentration are monitored. When the COD removal rate reaches 90%, the second incubation ends, and activated sludge adapted to polymer-containing sewage is obtained.

[0040] During the second incubation, when the COD removal rate reaches 90% and remains stable, it proves that the acclimation of the activated sludge is successful, and activated sludge adapted to polymer-containing sewage is obtained, and the second incubation ends.

[0041] In a preferred embodiment, the polymer-containing sewage includes polymers, petroleum hydrocarbons, and solid particulate suspensions; preferably, the concentration of polymers in the polymer-containing sewage is 100-200 mg / L, the concentration of petroleum hydrocarbons is 10-300 mg / L, including but not limited to 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, or 300 mg / L, and the concentration of solid particulate suspensions is 30-2000 mg / L, including but not limited to 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, or 2000 mg / L; preferably, the polymers include one or more of, but are not limited to, polyacrylamide, polyvinyl alcohol, polystyrene, or polyurethane; preferably, the oil-containing sewage includes petroleum hydrocarbons and solid particulate suspensions; preferably, the concentration of petroleum hydrocarbons in the oil-containing sewage is 100-500 mg / L, including but not limited to 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, or 500 mg / L, and the solid particulate suspensions are 30-2000 mg / L, including but not limited to 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, or 2000 mg / L; preferably, the petroleum hydrocarbons include one or more of, but are not limited to, alkanes, alkenes, or aromatic hydrocarbons; preferably, in the first sewage mixture, the volume ratio of the oil-containing sewage to the polymer-containing sewage is (5-1):1, including but not limited to 5:1, 4:1, 3:1, 2:1, or 1:1; preferably, in the second sewage mixture, the volume ratio of the oil-containing sewage to the polymer-containing sewage is (3-1):1, including but not limited to 3:1, 2:1, or 1:1; preferably, in the last cycle of the second incubation, the volume ratio of the oil-containing sewage to the polymer-containing sewage is 1:1.

[0042] The polymers in the polymer-containing sewage refer to sewage containing various polymers generated from industrial production, chemical processing, wastewater treatment plants, or other production processes. Common polymers include, but are not limited to, polyacrylamide, polyvinyl alcohol, polystyrene, polyurethane, polymer gels, polymer particles, and polymer residues, etc. The petroleum hydrocarbons in the polymer-containing sewage and the oil-containing sewage refer to wastewater of petroleum derivatives, mainly hydrocarbons. In this application, using a sewage mixture composed of polymer-containing sewage and oil-containing sewage with a high concentration of polymers to incubate and domesticate activated sludge can improve the incubation efficiency, obtain the effect of domesticating the activated sludge to adapt to the polymer-containing sewage, and can effectively remove the polymer-containing sewage with a low polymer concentration.

[0043] During the incubation of the activated sludge in this application, continuously increasing the volume ratio of the polymer-containing sewage helps the microorganisms in the activated sludge to better adapt to and degrade the organic matter in the polymer-containing sewage in the wastewater, thereby improving the domestication efficiency.

[0044] In a preferred embodiment, the volume ratio of the activated sludge to the first sewage mixture is 1:(8 - 10); preferably, the volume ratio of the activated sludge to the second sewage mixture is 1:(8 - 10).

[0045] In a preferred embodiment, the aeration volume of the aeration disturbance is 1 - 5 mg / L, and the aeration time is 20 - 23 h; preferably, the dissolved oxygen in the first incubation is 1 - 2 mg / L; preferably, the dissolved oxygen in the second incubation is 3 - 4 mg / L.

[0046] In the first incubation, aeration can ensure the full mixing of the mud and water. In the middle and late stages of the cultivation of the activated sludge, that is, when the sewage COD removal rate of the activated sludge reaches 50 - 70%, the activated sludge is mature. At this time, the activity is enhanced, and the zoogloea flocs of the first activated sludge also become larger. However, if aeration continues at this time, the shear force generated by aeration will break up the zoogloea, which is not conducive to the formation of the zoogloea and will accelerate the aging of the sludge. Therefore, when the first activated sludge is mature, it is necessary to increase the dissolved oxygen content to carry out the second incubation, so that oxygen can penetrate into the interior of the flocs, enabling the microorganisms inside to absorb sufficient oxygen, and the flocs have good sedimentation and activity. However, if the concentration of the dissolved oxygen is too high, the microorganisms tend to use oxygen as an oxidant and prefer to choose the oxygenolysis method to degrade the organic matter rather than using aerobic respiration to degrade the organic matter. Therefore, if the dissolved oxygen content is too high during the incubation process, it will lead to a change in the metabolic pathway of the microorganisms in the activated sludge, thereby reducing the domestication efficiency of the activated sludge and the final activity of the activated sludge.

[0047] In a preferred embodiment, the time of both the first incubation and the second incubation is 22 - 24 h, and the time for static stratification is 25 - 45 min; preferably, the number of cycles of the first incubation is 1 - 5 times; preferably, the number of cycles of the second incubation is 1 - 10 times; preferably, each cycle in the first incubation and the second incubation takes 1 day.

[0048] Using parameters outside the parameter range of the preparation method of this application cannot achieve the incubation and domestication effect in this application, and activated sludge adapted to polymer-containing sewage in this application cannot be obtained.

[0049] In the second typical embodiment of this application, an activated sludge adapted to polymer-containing sewage is provided, and the activated sludge adapted to polymer-containing sewage is the sludge obtained by the preparation method of any of the above-mentioned activated sludges adapted to polymer-containing sewage.

[0050] In the third typical embodiment of the present application, a sewage treatment method is provided. The activated sludge adapted to polymer-containing sewage or the activated sludge obtained by the preparation method of any of the above-mentioned activated sludges adapted to polymer-containing sewage is used to treat the polymer-containing sewage to be treated; the polymer concentration in the polymer-containing sewage to be treated is 0.1-1000 mg / L, including but not limited to 0.1, 0.5, 10, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300, 400, 500, 600, 700, 800, 900 or 1000 mg / L.

[0051] In a preferred embodiment, the sewage treatment method includes: mixing the activated sludge and the polymer-containing sewage to be treated at a volume ratio of 1:(1-10), performing continuous aeration and agitation, controlling the dissolved oxygen at 4-5 mg / L, pH at 7-8, operating for 1 cycle, and 1 cycle is 2-10 days; preferably, after operating for 1 cycle, standing for stratification and removing the supernatant, adding new polymer-containing sewage to be treated for sewage treatment, and the activated sludge is used for a total of 5 cycles in the sewage treatment method.

[0052] The process schematic diagram of sewage treatment in the present application is as Figure 1 shown. First, it is necessary to pass through a sewage regulating tank to regulate the water quality and quantity of the sewage to be stable. At the same time, the baffle of the regulating tank can remove substances such as floating oil in the sewage. The bottom of the tank can collect and precipitate large particles that are easy to settle. According to the water quality conditions of the polymer-containing sewage, the pH value of the sewage is adjusted to 7-8 so that the microorganisms in the activated sludge can have a better growth state. The biological reaction tank adopts an aerobic treatment unit. The aerobic tank degrades the organic matter in the water significantly through the metabolism of heterotrophic bacteria. After treatment, the biological sludge passes through a sedimentation tank to complete the separation of mud and water. The supernatant is discharged up to standard, and a part of the precipitated biological sludge is refluxed to the aerobic tank, and a small part is discharged as excess sludge to achieve a cycle. During this process, the proportion of polymer-containing sewage in the supplemented mixed sewage is continuously increased, and the polymer-containing sewage is polymer-containing sewage with a high polymer concentration. After being domesticated for a certain number of days and reaching equilibrium in indicators, activated sludge adapted to polymer-containing sewage is obtained. Finally, the domesticated activated sludge adapted to polymer-containing sewage is used to continue treating the polymer-containing sewage with a low polymer concentration through this process.

[0053] The beneficial effects of the present application will be further explained in detail below with specific embodiments.

[0054] Example 1

[0055] 1. First Incubation: On the 1st day: Mix the activated sludge with the sewage mixture (oily sewage: polymer-containing sewage = 5:1, volume ratio) at a volume ratio of 1:10. Among them, the concentration of the polymer in the polymer-containing sewage is 150 mg / L, the concentration of petroleum hydrocarbons is 200 mg / L, and the concentration of solid particle suspended matter is 1000 mg / L; the concentration of petroleum hydrocarbons in the oily sewage is 300 mg / L, and the solid particle suspended matter is 1000 mg / L. Control the pH to be 7.5 ± 0.5, the temperature is controlled at 25 ± 3 °C, and the dissolved oxygen is between 1.5 ± 0.5 mg / L. Add sucrose, diammonium phosphate, and urea (the mass ratio of C:N:P is 100:5:1). Each 24 h is a treatment cycle. After aeration for 23 h, let it stand for stratification to drain the supernatant and supplement the mixed sewage (change the ratio of oily sewage: polymer-containing sewage to 4:1), sucrose, diammonium phosphate, and urea, and maintain the C:N:P ratio of 100:5:1. On the 3rd day, carry out the above-mentioned cyclic treatment cycle in step 1 in sequence. On the 4th, 5th, and 6th days, supplement the mixed sewage (change the ratio of oily sewage: polymer-containing sewage to 3:1), sucrose, diammonium phosphate, and urea every day, and also maintain the C:N:P ratio of 100:5:1; on the 5th day, when the COD removal rate of the activated sludge reaches 70%, the first incubation ends.

[0056] 2. Second Incubation: Start the second incubation from the 6th day, increase the dissolved oxygen to 3.5 ± 0.5 mg / L until the end. On the 7th, 8th, and 9th days, supplement the mixed sewage (change the ratio of oily sewage: polymer-containing sewage to 2:1), sucrose, diammonium phosphate, and urea every day, and also maintain the C:N:P ratio of 100:5:1. From the 10th to the 14th day, supplement the mixed sewage (change the ratio of oily sewage: polymer-containing sewage to 1:1), sucrose, diammonium phosphate, and urea every day, and also maintain the C:N:P ratio of 100:5:1. When the COD removal rate of the activated sludge reaches the highest level and remains at about 90%, stop the second incubation to obtain the activated sludge adapted to the polymer-containing sewage.

[0057] Determine the domestication effect after the incubation of the activated sludge adapted to the polymer-containing sewage by monitoring the 30-min SVI, the COD of the influent and effluent every day, and the MLSS (activated sludge concentration).

[0058] The 30-minute sedimentation ratio (Sludge Volume Index, SVI) is an important parameter used to evaluate the sedimentation performance of activated sludge. SVI is calculated by measuring the volume change of the sludge settling in the container within a certain period of time (usually 30 minutes) in the wastewater treatment system. The higher the SVI value, the worse the sedimentation performance of the activated sludge. If the SVI value is lower, it means that the sludge settles relatively better in water.

[0059] SVI = V / H, where V is the volume of the supernatant (unit: milliliters) and H is the total height after sludge sedimentation (supernatant + deposited sludge) (unit: mm).

[0060] The measuring method for COD of the influent and effluent is as follows:

[0061] COD (mg / L) = C × (V0 - V1) × 8000 / V;

[0062] In the formula: C ------ the molar concentration of the ammonium ferrous sulfate standard solution, mol / L;

[0063] V0 ------ the volume of the ammonium ferrous sulfate standard solution consumed in the blank titration, mL;

[0064] V1 ------ the volume of the ammonium ferrous sulfate standard solution consumed in the titration of the wastewater sample, mL;

[0065] V ------ the volume of the wastewater sample, mL.

[0066] The measuring method for MLSS is as follows:

[0067] 1) Dry the prepared quantitative filter paper in a forced-air drying oven at 103°C to 105°C for 2 h until constant weight, cool it in a desiccator for half an hour, and then weigh it, denoted as m1;

[0068] 2) Lay the filter paper flat on a suction filtration funnel, and pour all V liters of the sludge for which the sedimentation ratio has been measured onto the dried filter paper for filtration;

[0069] 3) After filtration, place the filter paper with the sludge on it in a forced-air drying oven at 103°C to 105°C for 2 h until constant weight, cool it in a desiccator for half an hour, and then weigh it, denoted as m2;

[0070] MLSS = (m2 - m1) / V, with the unit of mg / L.

[0071] In this embodiment, the variation of the 30-minute sedimentation ratio (SV) of the activated sludge with the domestication (incubation) time during the domestication (incubation) process of the activated sludge is as Figure 2 shown. When the dissolved oxygen was low from the 1st day to the 5th day, the sedimentation ratio was low. After the dissolved oxygen increased on the 6th day, the sedimentation ratio increased. After the 10th day, the 30-minute SV of the activated sludge reached the highest level and then tended to be stable.

[0072] In this embodiment, the variation of MLSS and pH with the domestication (incubation) time during the domestication process of the activated sludge is as Figure 3 shown. During the whole domestication (incubation) process, the pH value was relatively stable. After the 10th day, MLSS reached the highest level and then tended to be stable.

[0073] In this example, the variations of influent COD, effluent COD and COD removal rate during the activated sludge domestication (incubation) process with respect to the domestication (incubation) time are as follows Figure 4 shown. After the 10th day, the COD removal rate of the activated sludge reached the highest level and remained at about 90%, indicating that the cultivation and domestication (incubation) process of the sludge microorganisms was successful.

[0074] Example 2

[0075] Mix the activated sludge adapted to polymer-containing sewage with the polymer-containing sewage with a low polymer concentration to be treated at a volume ratio of 1:10, conduct continuous aeration and agitation, while controlling the dissolved oxygen at 4.5 ± 0.5 mg / L and pH at 7.5 ± 0.5. Add sucrose, diammonium phosphate and urea, and control the C:N:P ratio to be 100:5:1; the operating time of each cycle is 24 h; after 23 h of aeration, let it stand for stratification and drain the supernatant to complete one cycle. At the same time, supplement with new polymer-containing sewage, add sucrose, diammonium phosphate and urea, control the C:N:P ratio to be 100:5:1, and conduct the next cycle of operation. A total of 10 cycles are carried out for a total of 10 days. Monitor the indicators of the supernatant every two cycles. The oil content, polymer concentration, suspended solid content and COD value of the polymer-containing sewage with a small amount of residues in this example are shown in Table 1.

[0076] Table 1

[0077]

[0078] The variation of the effluent COD in this example is as follows Figure 5 shown. After 10 cycles of treatment, the effluent COD is 80.0 mg / L, and the removal rate is 72.7%, meeting the first-class standard discharge requirements of the Integrated Wastewater Discharge Standard GB8978-1996. The variation of the effluent polymer concentration is as follows Figure 6 shown. After 10 cycles of microbial degradation, the effluent polymer concentration drops from 2.9 mg / L to 1.0 mg / L, and the removal rate is 65.5%. The variation of the oil content in the effluent is as follows Figure 7 shown. After 10 cycles of microbial degradation, the oil content concentration in the effluent drops from 10.4 mg / L to 2.5 mg / L, and the removal rate is 76.0%. The suspended solid content in the influent is only 21.0 mg / L. After treatment, the suspended solid content in the effluent could not be detected due to its too low content, and this value can be regarded as zero.

[0079] The effluent COD is 80.0 mg / L, the polymer concentration is 1.0 mg / L, and the oil content is 2.5 mg / L. This biological treatment process has a better effect on treating the polymer-containing wastewater pretreated by the superhydrophobic sponge, the effluent water quality is stable, and the effluent water quality can meet the first-class standard discharge requirements of the Integrated Wastewater Discharge Standard GB8978-1996.

[0080] Example 3

[0081] Mix the activated sludge adapted to polymer-containing sewage with the raw polymer-containing sewage to be treated at a volume ratio of 1:10, conduct continuous aeration and agitation, and at the same time control the dissolved oxygen at 4.5 ± 0.5 mg / L and the pH at 4.5 ± 0.5. Add sucrose, diammonium phosphate and urea, and control the C:N:P ratio to be 100:5:1; the operating time for each cycle is 24 h; after 23 h of aeration, let it stand for stratification and drain the supernatant to complete one cycle. At the same time, supplement new polymer-containing sewage, and add sucrose, diammonium phosphate and urea when necessary, control the C:N:P ratio to be 100:5:1, and conduct the operation of the next cycle. A total of 5 cycles are carried out for 10 days. Monitor the indicators of the supernatant every two cycles. The oil content, polymer concentration, suspended solid content and COD value of the raw polymer-containing sewage in this example are shown in Table 2.

[0082] Table 2

[0083]

[0084] During the stable operation test of this example, the change of the effluent COD is as Figure 8 shown. After 10 cycles of treatment, the effluent COD is 300.0 mg / L, and the removal rate is 88.7%. The change of the effluent polymer concentration is as Figure 9 shown. After 10 cycles of microbial degradation, the effluent polymer concentration drops from 27.4 mg / L to 7.5 mg / L, and the removal rate is 72.6%. The change of the oil content in the effluent is as Figure 10 shown. After 10 cycles of microbial degradation, the oil content concentration in the effluent drops from 176.6 mg / L to 35.0 mg / L, and the removal rate is 80.2%.

[0085] The suspended solids in the raw polymer-containing sewage are mainly rock debris and clay particles. Since the polymer in the polymer-containing sewage is an anionic polymer and the soil surface is negatively charged, they repel each other and are difficult to aggregate and settle. In addition, the presence of the polymer in the water increases the viscosity of the water, making it difficult for the suspended solids in the water to settle.

[0086] The change of the suspended solid content in the effluent of this application is as Figure 11 shown. After microbial degradation, the suspended solid content in the effluent drops from 1670.0 mg / L to 58.8 mg / L. The degradation time has little effect on the suspended solid content, and the removal rate is 96.5%, which can meet the first-class standard discharge requirements of GB8978-1996 Comprehensive Wastewater Discharge Standard.

[0087] Example 4

[0088] The domestication method of the activated sludge is as in Example 1, with the only difference being that the temperature is 50 ± 5 °C to obtain the domesticated activated sludge.

[0089] The activated sludge in this example was used to treat polymer-containing wastewater, and the treatment method was the same as that in Example 2. The results were as follows: the COD removal rate was 78.3%, the polymer concentration removal rate was 68.1%, and the oil content removal rate was 70.9%. When the temperature is too high, the dissolved oxygen concentration decreases, and secondly, the activity of microbial enzymes in the activated sludge also decreases, thereby reducing the activity of the activated sludge.

[0090] Example 5

[0091] The domestication method of the activated sludge was as in Example 1, with the only difference being that the dissolved oxygen concentration in the first incubation and the second incubation was increased to 7 mg / L to obtain domesticated activated sludge.

[0092] The above-mentioned activated sludge was used to treat polymer-containing wastewater, and the treatment method was the same as that in Example 2. The COD removal rate was 75.4%, the polymer concentration removal rate was 65.8%, and the oil content removal rate was 67.7%. This is because when the dissolved oxygen concentration is too high, microorganisms tend to use oxygen as an oxidant and prefer to choose the oxygenolysis method for the degradation of organic matter rather than using the aerobic respiration process to degrade organic matter. Therefore, when the dissolved oxygen content is too high in this example, it leads to a change in the microbial metabolic pathway in the activated sludge, thereby reducing the activity of the activated sludge.

[0093] Comparative Example 1

[0094] The activated sludge was incubated by using the incubation means in the prior art, that is, the activated sludge was only incubated with oily wastewater, and the incubation conditions were as in Example 1 of this application. At the end of the incubation, the COD could only be maintained at about 60%, proving that the domestication of the activated sludge was unsuccessful.

[0095] The sludge obtained by domestication with the above-mentioned oily wastewater was used to treat polymer-containing wastewater with a small amount of residues, and the treatment method was the same as that in Example 2. The COD removal rate was 69.4%, the polymer concentration removal rate was 56.7%, and the oil content removal rate was 61.3%. The polymer-containing wastewater raw water was treated with the activated sludge after incubation in Comparative Example 1, and the treatment method was the same as that in Example 3. The COD removal rate was 48.1%, the polymer concentration removal rate was 51.5%, and the oil content removal rate was 47.8%.

[0096] From the above description, it can be seen that the above examples of the present invention achieved the following technical effects: The activated sludge adapted to polymer-containing wastewater prepared by this application has good treatment effects on low-concentration polymer solids, suspended solid particles, and oil content in the sludge to be treated. It not only found a utilization way for the polymer in the polymer-containing wastewater, saved the cost of supplementing carbon sources and nitrogen sources, but also solved the problems of low activity of the activated sludge in the sewage treatment plant, difficulty in efficiently treating polymer-containing wastewater with low polymer concentration, and other residues.

[0097] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of activated sludge adapted to polymer-containing sewage, characterized in that, The preparation method includes: Using the initial activated sludge to perform a first treatment, static stratification, and removal of the supernatant on the first sewage mixture in sequence to complete one cycle in the first incubation; The cycle in the first incubation includes one or more times until the COD removal rate of the initial activated sludge reaches 50-70%, obtaining the first activated sludge and starting the second incubation; The second incubation includes: using the first activated sludge to perform a second treatment, static stratification, and removal of the supernatant on the second sewage mixture in sequence to complete one cycle in the second incubation, obtaining the second activated sludge; The second incubation cycle is carried out one or more times until the sewage COD removal rate of the second activated sludge reaches the highest level and stabilizes, obtaining the activated sludge adapted to the polymer-containing sewage; Wherein, During the first treatment and the second treatment, aeration disturbance is continuously carried out; Both the first sewage mixture and the second sewage mixture include oily sewage and the polymer-containing sewage; The volume ratio of the polymer-containing sewage in the second sewage mixture is greater than the volume ratio of the polymer-containing sewage in the first sewage mixture; In the first incubation and the second incubation, the volume ratio of the polymer-containing sewage in the sewage mixture used for each cycle remains unchanged or increases.

2. The preparation method according to claim 1, characterized in that, In the first incubation and the second incubation, the pH of the initial activated sludge, the first activated sludge, and the second activated sludge is 7-8.5, and the temperature is 20-30°C; Preferably, in each cycle of the first incubation and the second incubation, nutrient components are added to the sludge; Preferably, the nutrient components include a carbon source, a nitrogen source, and a phosphorus source; Preferably, the carbon source includes sucrose; Preferably, the nitrogen source and the phosphorus source are inorganic salts, and the inorganic salts include diamine phosphate and urea; Preferably, in the nutrient components, the mass ratio of C element: N element: P element is 100:5:

1.

3. The preparation method according to claim 1, characterized in that, In the second incubation, the influent COD, the effluent COD, and the activated sludge concentration are monitored. When the COD removal rate reaches 90%, the second incubation ends, and the activated sludge adapted to the polymer-containing sewage is obtained.

4. The preparation method according to claim 1, characterized in that, The polymer-containing sewage includes polymers, petroleum hydrocarbons, and solid particle suspensions; Preferably, the concentration of the polymer in the polymer-containing sewage is 100-200 mg / L, the concentration of the petroleum hydrocarbon is 10-300 mg / L, and the concentration of the solid particle suspension is 30-2000 mg / L; Preferably, the polymer includes any one or more of the following: polyacrylamide, polyvinyl alcohol, polystyrene, or polyurethane; Preferably, the oily sewage includes the petroleum hydrocarbon and the solid particle suspension; Preferably, the concentration of the petroleum hydrocarbon in the oily sewage is 100-500 mg / L, and the solid particle suspension is 30-2000 mg / L; Preferably, in the first sewage mixture, the volume ratio of the oily sewage to the polymer-containing sewage is (5-1):1; Preferably, in the second sewage mixture, the volume ratio of the oily sewage to the polymer-containing sewage is (3-1):1; Preferably, in the last cycle of the second incubation, the volume ratio of the oily sewage to the polymer-containing sewage is 1:

1.

5. The preparation method according to claim 1, characterized in that, The volume ratio of the activated sludge to the first sewage mixture is 1:(8 - 10); Preferably, the volume ratio of the activated sludge to the second sewage mixture is 1:(8 - 10).

6. The preparation method according to claim 1, wherein The aeration volume of the aeration disturbance is 1 - 5 mg / L, and the aeration time is 20 - 23 h; Preferably, the dissolved oxygen in the first incubation is 1 - 2 mg / L; Preferably, the dissolved oxygen in the second incubation is 3 - 4 mg / L.

7. The preparation method according to claim 1, characterized in that, The time of both the first incubation and the second incubation is 22 - 24 h, and the time of static settling and stratification is 25 - 45 min; Preferably, the number of cycles of the first incubation is 1 - 5 times; Preferably, the number of cycles of the second incubation is 1 - 10 times; Preferably, each cycle in the first incubation and the second incubation takes 1 day.

8. The activated sludge adapted to polymer-containing sewage prepared by the method for preparing activated sludge adapted to polymer-containing sewage according to any one of claims 1 - 7.

9. A sewage treatment method, characterized in that, Using the activated sludge adapted to polymer-containing sewage according to claim 8, or the activated sludge prepared by the method for preparing activated sludge adapted to polymer-containing sewage according to any one of claims 1 - 7, to treat the polymer-containing sewage to be treated; The polymer concentration in the polymer-containing sewage to be treated is 0.1 - 100 mg / L.

10. The sewage treatment method according to claim 9, wherein The sewage treatment method includes: mixing the activated sludge and the polymer-containing sewage to be treated in a volume ratio of 1:(1 - 10), performing continuous aeration disturbance, controlling the dissolved oxygen at 4 - 5 mg / L, pH at 7 - 8, and operating for 1 cycle, and the 1 cycle is 2 - 10 days; Preferably, after operating for the 1 cycle, statically settle and stratify and remove the supernatant, add new polymer-containing sewage to be treated for sewage treatment, and the activated sludge is used for a total of 5 cycles in the sewage treatment method.

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