Method for improving resistance to toxic impact of compound pollutants in nitrification process of activated sludge

Abstract

The invention discloses a method for improving resistance of activated sludge to toxic impact of composite pollutants in a nitrification process, and belongs to the technical field of multi-component composite polluted water treatment. The method comprises the following steps: respectively determining the semi-inhibitory concentration IC50 of Cu < 2 + >, CIP and nano plastic in the activated sludge nitrification process; according to the method, the concentration of bovine albumin remission liquid added into polluted wastewater is 0.5 IC50 under the background that the ammonia oxidation process and the nitrite oxidation process of PE-NPs and PBAT-NPs are IC50, and the shake-up time of bovine albumin and mixed pollutants is set to be 60-90 min. The method for relieving the toxic impact of the nano-plastic, heavy metal and antibiotic composite pollutants on the activated sludge nitrification process has the characteristics of rapidness, effectiveness, simplicity in operation, safety, harmlessness and suitability for popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-component composite polluted water treatment, and specifically relates to a method for improving the resistance of activated sludge nitrification process to the toxic impact of composite pollutants. Background Art

[0002] In the process of livestock and poultry breeding, heavy metal copper (Cu) is often used as a feed additive to improve the production performance of livestock and poultry and maintain the health of the body. However, since the intestines of livestock and poultry can usually only absorb a small part of heavy metal elements, the remaining 60-70% of heavy metals are excreted from the body of livestock and poultry with feces and urine. In addition, ciprofloxacin (CIP), as a third-generation quinolone antibacterial drug, has been added to feed in large quantities for a long time to enhance the resistance of livestock and poultry and improve the breeding efficiency of livestock and poultry due to its broad-spectrum antibacterial activity and good bactericidal effect. Only part of Cu and CIP will be absorbed by the body of livestock and poultry, and most of the drugs will be excreted in the form of feces and urine or remain in the livestock and poultry breeding water environment. In the breeding production process, plastic products are widely used in various links of livestock and poultry breeding because of their characteristics of easy installation, corrosion resistance, long service life, good waterproof performance, and good sealing performance, such as breeding fence partitions, breeding pads, feed storage and transportation containers, ventilation ducts, greenhouse construction, etc. However, plastic products are decomposed into nanoplastic particles with smaller particle size under the action of weathering, mechanical wear, photocatalytic degradation, and biodegradation, which are distributed in the livestock and poultry breeding environment. This results in composite pollution consisting of nanoplastic particles, antibiotics and heavy metals, which is particularly prominent in livestock and poultry breeding environments, and eventually enters livestock and poultry breeding wastewater through washing in the breeding environment and excretion after livestock and poultry ingestion, so that livestock and poultry breeding wastewater contains not only a large amount of organic matter and nitrogen and other pollutants, but also often contains nanoplastic particles, antibiotics and heavy metals at different concentrations. In actual production and life, in addition to livestock and poultry wastewater containing heavy metals, antibiotics and nanoplastics at the same time, the emission of harmful substances, drug residues, and improper use of plastic products during the production and processing process will cause heavy metals, antibiotics and nanoplastics to exist in the wastewater environment at the same time.

[0003] Activated sludge is one of the common methods for wastewater treatment. The presence of heavy metals, antibiotics and nanoplastic particles can cause toxic inhibition to the activated sludge nitrification process by inducing oxidative stress, destroying cell structure, changing microbial community structure, and inhibiting bacterial cell metabolism. In addition, nanoplastics have a carrier function and can adsorb Cu 2+ and CIP, and in Cu 2+ Under the action of nanoplastics, the adsorption of CIP may change, so Cu 2+ The toxic effects between CIP and nanoplastic particles are not simply superimposed, but may also result in a more toxic synergistic effect, thereby showing a stronger toxic inhibitory effect on the activated sludge nitrification process.

[0004] At present, most of the research on wastewater treatment focuses on the inhibition of activated sludge nitrification process by single heavy metals or antibiotics and binary combined pollution of heavy metals and antibiotics, but the establishment of a method to alleviate the inhibition of activated sludge nitrification process by ternary combined pollution composed of heavy metals, antibiotics and nanoplastics has not yet been involved. Therefore, it is necessary to develop a method to improve the activated sludge nitrification process to resist the combined toxic impact of nanoplastics, heavy metals and antibiotics, so as to alleviate the toxic effects of the combined effects of nanoplastics, heavy metals and antibiotics on the activated sludge nitrification process. Summary of the invention

[0005] In view of the above-mentioned deficiencies and defects of the prior art, the purpose of the present invention is to provide a method for improving the resistance of activated sludge nitrification process to the toxic impact of nanoplastics, heavy metals and antibiotics composite pollutants, and to solve the technical problem of poisoning in the activated sludge nitrification process caused by nanoplastics, heavy metals and antibiotics composite pollutants according to the different types of nanoplastics, thereby reducing the denitrification efficiency of the activated sludge process. The scheme has high treatment efficiency, simple operation, green environmental protection and no toxicity, and can be extended to the toxicity mitigation effect of the activated sludge treatment process of wastewater containing heavy metals, antibiotics, and nanoplastics.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for improving the resistance of activated sludge nitrification process to the toxic impact of composite pollutants is to add bovine albumin to the composite pollutant wastewater in the activated sludge nitrification process and oscillate and mix evenly;

[0008] The composite pollutant is a composite of nano plastics and any one or two of heavy metals and antibiotics.

[0009] Furthermore, in the method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants, the nanoplastic is biodegradable poly (butylene adipate / terephthalate) nanoplastic PBAT-NPs or non-biodegradable polyethylene nanoplastic PE-NPs.

[0010] Preferably, the composite pollutant is Cu 2+ +PE-NPs, Cu 2+ +PBAT-NPs, CIP+PE-NPs, CIP+PBAT-NPs, Cu 2+ +CIP+PE-NPs, Cu 2+ +One of the CIP+PBAT-NPs complexes.

[0011] Preferably, the particle sizes of the PBAT-NPs and PE-NPs are both 800 nm.

[0012] A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants as described in any one of the above, the specific steps of the method are as follows:

[0013] 1) Determine the half inhibition concentration (IC) of nanoplastics in the composite pollutants in the activated sludge nitrification process 50 , the activated sludge nitrification process includes an ammonia oxidation process and a nitrite oxidation process;

[0014] 2) According to the IC of nanoplastics in the ammonia oxidation process and nitrite oxidation process 50 , add bovine albumin mitigation solution to the wastewater with complex pollutants, and oscillate to mix evenly;

[0015] 3) The water sample treated in step 2) is placed in activated sludge for aeration treatment, and the supernatant separated after static sedimentation is the purified water.

[0016] Further, in the method for improving the resistance of activated sludge nitrification process to the toxic impact of composite pollutants, in step 2), in the ammonia oxidation process and the nitrite oxidation process, the concentration of bovine albumin mitigation solution added is 0.5IC in the ammonia oxidation process and the nitrite oxidation process, respectively. 50 .

[0017] Furthermore, in the method for improving the resistance of activated sludge nitrification process to the toxic impact of composite pollutants, in step 2), the volume ratio of the composite pollutant wastewater to the bovine albumin mitigation solution is 1:1.

[0018] Furthermore, in the method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants, in step 2), the oscillation speed is 300 rpm.

[0019] Furthermore, in the method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants, in step 2), the oscillation mixing time is 60 min-90 min in both the ammonia oxidation process and the nitrite oxidation process.

[0020] Preferably, in step 2), when the nanoplastic is PE-NPs, the oscillation mixing time is 90 min in both the ammonia oxidation process and the nitrite oxidation process; when the nanoplastic is PBAT-NPs, the oscillation mixing time is 60 min in both the ammonia oxidation process and the nitrite oxidation process.

[0021] The beneficial effects of the present invention are:

[0022] 1. The method of the present invention determines the half-inhibitory concentration of heavy metals, antibiotics and nanoplastic particles in the activated sludge nitrification process, and determines the concentration of bovine albumin mitigation solution based on this, and selects the appropriate contact time between nanoplastic particles and bovine albumin to ensure that bovine albumin can be fully adsorbed on the nanoplastic particles to form an ecological corona. Appropriate contact time and appropriate bovine albumin concentration allow bovine albumin to form a soft corona on the surface of nanoplastic particles. During this process, bovine albumin with high abundance in the environment is loosely and reversibly bound to nanoplastic particles, which makes the formed ecological corona exchange materials with the surrounding environment faster, and can adsorb more heavy metals and antibiotics in the environment to reduce the concentration of free pollutants in the environment, thereby achieving the effect of improving the activated sludge nitrification process to resist the combined toxic impact of nanoplastics, heavy metals and antibiotics.

[0023] 2. The method of the present invention is easy to operate, simple and easy to operate, has controllable reaction, is safe and harmless, and is suitable for promotion. It can be applied to the treatment of wastewater containing multiple composite pollutants, especially to the treatment of wastewater containing multiple composite pollutants containing plastic particles. The addition of bovine albumin mitigation solution promotes the formation of an ecological crown on the surface of nanoplastics, and the formed ecological crown can absorb more Cu in the environment. 2+ and CIP, by reducing the free concentration of pollutants in the environment to alleviate Cu 2+ The combined pollution of CIP and nano-plastics has a toxic effect on the nitrification process of activated sludge. At the same time, no other polluting substances are produced during the treatment process. It is healthier, more environmentally friendly and non-toxic, and is a green and environmentally friendly treatment method.

[0024] 3. The present invention provides a method for improving the resistance of activated sludge nitrification process to the combined toxic impact of nanoplastics, heavy metals and antibiotics, which can alleviate the toxic impact of ammonia oxidation rate in activated sludge nitrification process by 67.89%-89.73%, and alleviate the toxic impact of nitrite oxidation rate in activated sludge nitrification process by 57.43%-95.29%. By adjusting the appropriate concentration of bovine albumin and the appropriate compounding time with nanoplastic particles, Cu 2+ This method can be extended to alleviate the toxic effects of combined pollution of heavy metals, antibiotics and nanoplastic particles on the activated sludge treatment process of wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a graph showing the changes in the adsorption ratio of different concentrations of BSA mitigation solutions on PE-NPs.

[0026] Figure 2 This is a graph showing the changes in the adsorption ratio of different concentrations of BSA mitigation solution on PBAT-NPs.

[0027] Figure 3 The graph shows the change in the binding constant between bovine albumin and nanoplastics at different contact times with PE-NPs (a) and PBAT-NPs (b).

[0028] Figure 4 Cu in the activated sludge nitrification process after adding bovine albumin 2+ , CIP and nano-plastic composite pollutants on SAOR and SNOR inhibition efficiency diagram, where G1 represents the pollutant composition Cu 2+ + PE-NPs, G2 indicates the pollutant composition is CIP + PE-NPs, G3 indicates the pollutant composition is Cu 2+ +CIP+PE-NPs, G4 indicates that the pollutant composition is Cu 2+ +PBAT-NPs, G5 indicates the pollutant composition is CIP+PBAT-NPs, G6 indicates the pollutant composition is Cu 2+ +CIP+PBAT-NPs. DETAILED DESCRIPTION

[0029] The following examples are only for describing the preferred embodiments of the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, any improvements made without departing from the present invention should be within the scope of protection of the present invention.

[0030] The activated sludge used in the examples and comparative examples of the present invention was taken from an aeration tank of a sewage treatment plant in Shenyang. A conical flask with a size of 500 mL was selected, and 300 mL of activated sludge and 200 mL of composite polluted water sample were added to each flask.

[0031] Example 1

[0032] Determine Cu 2+ The half inhibition concentration (IC50) of CIP, PE-NPs and PBAT-NPs on the nitrification process of activated sludge process 50 ): Different concentrations of Cu were prepared by nutrient solution 2+ , CIP, PE-NPs and PBAT-NPs solutions, and the inhibition rate of activated sludge nitrification process was modeled by concentration gradient experiment. The SAOR inhibition rate and SNOR inhibition rate were used to determine the Cu 2+ The half inhibition concentration (IC ) of CIP and nanoplastic particles for ammonia oxidation and nitrite oxidation 50 ).

[0033] For the ammonia oxidation process: set the CH 3 The concentration of COONa is 440mg / L, NH 4 The concentration of Cl is 136 mg / L, KH 2 PO4 The concentration of Cu was 13 mg / L, and the nutrient solution was set 2+ The concentration gradient of the solution is 20, 40, 60, 80, 100 mg L -1 ; The concentration gradient of CIP solution was set to 2, 5, 10, 20, and 50 mg L -1 The concentration gradients of PBAT-NPs and PE-NPs solutions were set to 90, 120, 150, 180, and 210 mg L -1 .

[0034] For nitrite oxidation process: set CH 3 The concentration of COONa is 440mg / L, NaNO 2 The concentration is 178mg / L, KH 2 PO 4 The concentration of Cu was 13 mg / L, and the nutrient solution was set 2+ The concentration gradient of the solution is 20, 40, 60, 80, 100 mg L -1 ; The concentration gradient of CIP solution was set to 2, 5, 10, 20, and 50 mg L -1 The concentration gradients of PBAT-NPs and PE-NPs solutions were set to 90, 120, 150, 180, and 210 mg L -1 .

[0035] 300 mL of activated sludge was added to each conical flask, and Cu 2+ 200 mL of CIP, PE-NPs and PBAT-NPs solution were added and fully aerated for 90 min. After the aeration, water samples were taken for ammonia oxidation rate (SAOR) detection and nitrite oxidation rate (SNOR) detection. The water samples were tested in triplicate.

[0036] Cu 2+ The half-inhibitory concentrations of CIP, PE-NPs and PBAT-NPs in the ammonia oxidation process and nitrite oxidation process are shown in Table 1.

[0037] Table 1 Concentration-effect fitting results of single pollutants based on SAOR and SNOR

[0038]

[0039] Example 2

[0040] Determined to effectively alleviate Cu 2+ +PE-NPs, CIP+PE-NPs, Cu 2+ +CIP+PE-NPs, Cu 2++PBAT-NPs, CIP+PBAT-NPs, Cu 2+ The appropriate concentration of bovine albumin (BSA) for the toxicity of the +CIP+PBAT-NPs composite pollutant to the nitrification process of the activated sludge process. BSA was dissolved in PBS buffer to prepare BSA mitigation solution, and the appropriate concentration of BSA mitigation solution was determined by concentration gradient experiment, in which the IC values ​​of PE-NPs and PBAT-NPs in the ammonia oxidation process and nitrite oxidation process were used respectively. 50 The value is the background, and the concentration gradient of BSA mitigation solution is set to 0.1IC 50 、0.5IC 50 、1.0IC 50 、1.5IC 50 、2.0IC 50 The prepared BSA mitigation solution was mixed with the PE-NPs and PBAT-NPs suspensions at a volume ratio of 1:1 and shaken evenly. After shaking evenly, water samples were taken for UV detection. The samples were taken in triplicate and the adsorption ratios of PE-NPs and PBAT-NPs to BSA were calculated. The results are shown in Figure 1 shown.

[0041] Depend on Figure 1 It can be seen that BSA mitigation solution is at 0.5IC 50 The adsorption ratio of BSA to PE-NPs and PBAT-NPs was the highest at 0.5IC, and then the adsorption ratio decreased. It may be that the protein corona formed by BSA on the surface of PE-NPs and PBAT-NPs caused a desorption reaction of the adsorbed BSA due to the dynamic adsorption process, which led to a decrease in the adsorption ratio of PE-NPs and PBAT-NPs to BSA. Therefore, the optimal concentration of BSA mitigation solution is 0.5IC 50 .

[0042] Example 3

[0043] The appropriate contact time between bovine albumin solution and PE-NPs and PBAT-NPs was determined. PBAT-NPs and PE-NPs were placed in ammonia oxidation process and nitrite oxidation process at 1.0 IC 50 The concentration of BSA mitigation solution was set to 0.5IC of PBAT-NPs and PE-NPs in the ammonia oxidation process and nitrite oxidation process. 50The prepared PE-NPs and PBAT-NPs suspensions and BSA mitigation solution were added to a conical flask at a volume ratio of 1:1, and then the conical flask was placed on a shaker and mixed at 300 rpm for 30 min, 60 min, 90 min, 120 min and 180 min. After the mixing time was over, the mixed solution of BSA with PE-NPs and PBAT-NPs was taken for BSA and nanoplastic composite detection. The samples were taken in triplicate, and the results were as follows Figure 2 As shown. Figure 2 It can be seen that when the nanoplastic is PE-NPs, 90 minutes is the optimal treatment time, and when the nanoplastic is PBAT-NPs, 60 minutes is the optimal treatment time.

[0044] Example 4

[0045] The toxicity mitigation effect of BSA on the activated sludge nitrification process against the combined toxicity shock of nanoplastics, heavy metals and antibiotics. 2+ The content of PE-NPs was 1.0IC in SAOR and SNOR. 50 It is worth exploring Cu 2 + The inhibition of SAOR and SNOR by binary composite pollutants with PE-NPs; the contents of CIP and PE-NPs in wastewater samples were set to 1.0IC corresponding to SAOR and SNOR 50 The value was used to explore the inhibition of SAOR and SNOR by CIP and PE-NPs binary composite pollutants; Cu 2+ The content of PBAT-NPs was 1.0IC in SAOR and SNOR. 50 It is worth exploring Cu 2+ The inhibition of SAOR and SNOR by binary composite pollutants with PBAT-NPs; the contents of CIP and PBAT-NPs in wastewater samples were set to 1.0IC corresponding to SAOR and SNOR 50 The value was used to explore the inhibition of SAOR and SNOR by CIP and PBAT-NPs binary composite pollutants; Cu 2+ The contents of CIP and PE-NPs were 1.0IC in SAOR and SNOR. 50 It is worth exploring Cu 2 + , CIP and PE-NPs ternary composite pollutants inhibit SAOR and SNOR; Set Cu in wastewater samples 2+ The contents of CIP and PBAT-NPs were 1.0IC in SAOR and SNOR. 50 It is worth exploring Cu 2+, the inhibition of SAOR and SNOR by the ternary complex of CIP and PBAT-NPs.

[0046] According to the types of nanoplastics contained in the water sample, when the nanoplastics in the water sample are PE-NPs, the concentration of BSA mitigation solution is set to the IC concentration of PE-NPs in SAOR and SNOR. 50 0.5 times the concentration, specifically 203.69 mg L -1 and 120.69 mg L -1 It is used to alleviate the inhibition of SAOR and SNOR by the complex composed of PE-NPs and other pollutants; when the nanoplastics in the water sample are PBAT-NPs, the concentration of BSA mitigation solution is set to the IC value of PNAT-NPs in SAOR and SNOR. 50 0.5 times the concentration, specifically 64.41 mg L -1 and 117.21 mg L -1 Used to alleviate the inhibition of SAOR and SNOR by the complex formed by PBAT-NPs and other pollutants. Add the prepared wastewater sample and BSA mitigation solution into a conical flask at a volume ratio of 1:1, and place it on a shaker and shake it at a speed of 300rpm. Shake the prepared BSA mitigation solution and wastewater sample in the group containing PE-NPs for 90 minutes, and shake the prepared BSA mitigation solution and wastewater sample in the group containing PBAT-NPs for 60 minutes.

[0047] 200 mL of the treated water sample was placed in a 500 mL conical flask, and 300 mL of activated sludge was added. The aeration time was set to 90 min. After the aeration was completed, the supernatant was taken for SAOR and SNOR detection. The reaction samples were prepared in triplicate. At the same time, a composite wastewater sample without the addition of BSA mitigation solution was used as a comparative example.

[0048] Cu in activated sludge nitrification process after adding BSA 2+ The mitigation efficiency of CIP and nanoplastic composite pollutants on the inhibition rate of SAOR and SNOR is as follows Figure 3 shown.

[0049] In summary, the present invention determines Cu 2+ The half inhibition concentration of CIP and different types of nanoplastics on the nitrification process of activated sludge process and the determination of the appropriate concentration of BSA and the appropriate contact time with nanoplastics, and the effect of Cu 2+The toxicity recovery effect of CIP and nano-plastic composite polluted wastewater on the activated sludge nitrification process is obvious, among which the toxicity recovery efficiency of activated sludge SAOR reaches 67.89%-89.73%, and the toxicity recovery efficiency of activated sludge SNOR reaches 57.43%-95.29%, both of which have good recovery effects. Therefore, according to different specific needs, water plants can select different nano-plastics according to their different IC values ​​under SAOR and SNOR. 50 The value is used as the background to select a more suitable amount of bovine albumin, thereby specifically improving the denitrification efficiency of activated sludge under the influence of heavy metal, antibiotic and nano-plastic composite pollutants. This method has the characteristics of fast repair speed, significant toxicity mitigation effect, simple and convenient operation, large processing capacity, and easy to master. It provides an effective method to alleviate the toxicity of wastewater with composite pollution of heavy metals, antibiotics and nano-plastic particles on the nitrification process of activated sludge.

Claims

1. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants, characterized in that: The method comprises adding bovine albumin to the composite pollutant wastewater in the activated sludge nitrification process, and oscillating and mixing the wastewater evenly; the composite pollutant is a composite of nano plastics and any one or two of heavy metals and antibiotics.

2. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 1, characterized in that: The nanoplastic is biodegradable poly(butylene adipate / terephthalate) nanoplastic PBAT-NPs or non-biodegradable polyethylene nanoplastic PE-NPs.

3. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 2, characterized in that: The composite pollutant is Cu 2+ +PE-NPs, Cu 2+ +PBAT-NPs, CIP+PE-NPs, CIP+PBAT-NPs, Cu 2+ +CIP+PE-NPs, Cu 2+ +One of the CIP+PBAT-NPs complexes.

4. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 3, characterized in that: The particle sizes of the PBAT-NPs and PE-NPs are both 800 nm.

5. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to any one of claims 1 to 4, characterized in that: The specific steps of the method are as follows: 1) Determine the half inhibition concentration (IC) of nanoplastics in the composite pollutants in the activated sludge nitrification process 50 , the activated sludge nitrification process includes an ammonia oxidation process and a nitrite oxidation process; 2) According to the IC of nanoplastics in the ammonia oxidation process and nitrite oxidation process 50 , add bovine albumin mitigation solution to the wastewater with complex pollutants, and oscillate to mix evenly; 3) The water sample treated in step 2) is placed in activated sludge for aeration treatment, and the supernatant separated after static sedimentation is the purified water.

6. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 5, characterized in that: In step 2), during the ammonia oxidation process and the nitrite oxidation process, the concentration of the bovine albumin mitigation solution added is 0.5IC 50 .

7. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 5, characterized in that: In step 2), the volume ratio of the composite pollutant wastewater to the bovine albumin mitigation solution is 1:

1.

8. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 5, characterized in that: In step 2), the oscillation speed is 300 rpm.

9. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 5, characterized in that: In step 2), during the ammonia oxidation process and the nitrite oxidation process, the oscillation mixing time is 60 min-90 min.

10. A method for improving the resistance of activated sludge nitrification process to the toxic impact of complex pollutants according to claim 9, characterized in that: In step 2), when the nanoplastic is PE-NPs, the oscillation mixing time is 90 minutes in both the ammonia oxidation process and the nitrite oxidation process; when the nanoplastic is PBAT-NPs, the oscillation mixing time is 60 minutes in both the ammonia oxidation process and the nitrite oxidation process.

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