A method for promoting polyphosphorus bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics

Abstract

The application discloses a method for promoting phosphorus removal in wastewater by using biodegradable microplastics, and belongs to the technical field of wastewater treatment. The method comprises the following steps: after mixed culture of phosphorus accumulating organisms (PAOs) and pretreated biodegradable microplastics, the mixture is loaded into a container and then is put into wastewater to realize phosphorus removal in wastewater; wherein, the biodegradable microplastics include one or both of polylactic acid (PLA) and polyhydroxyalkanoate (PHA). The biodegradable microplastics can provide additional carbon source for the phosphorus accumulating organisms, and can enhance the activity of the phosphorus accumulating organisms. The biodegradable microplastics are more easily attached by microorganisms, and the addition of the biodegradable microplastics can provide more attachment sites for the phosphorus accumulating organisms. By adjusting the type and particle size of the added biodegradable microplastics, the phosphorus removal capacity of the phosphorus accumulating organisms can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wastewater treatment, and particularly relates to a method for reducing phosphorus in wastewater by using biodegradable microplastics to promote polyphosphorus bacteria. BACKGROUND

[0002] Phosphorus is the main factor of water eutrophication, so it is particularly important to remove phosphorus from water bodies to prevent water eutrophication. At present, most existing sewage treatment plants use biological phosphorus removal technology, which is mainly dominated by polyphosphorus bacteria. By taking advantage of the characteristics of polyphosphorus bacteria that can absorb excess phosphorus under aerobic conditions, the phosphorus in wastewater can be removed. However, in actual situations, the phosphorus absorption capacity of polyphosphorus bacteria is affected by various factors, making it difficult to meet the discharge standards of phosphorus in effluent. SUMMARY

[0003] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0004] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0005] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art and provide a method for reducing phosphorus in wastewater by using biodegradable microplastics to promote polyphosphorus bacteria.

[0006] To solve the above technical problems, the present application provides the following technical solutions: including,

[0007] The polyphosphorus bacteria (PAOs) are mixed and cultured with the pretreated biodegradable microplastics, then loaded into a container and discharged into wastewater to reduce the phosphorus in the wastewater.

[0008] The biodegradable microplastics include one or both of polylactic acid (PLA) and polyhydroxyalkanoate (PHA).

[0009] As a preferred embodiment of the method for reducing phosphorus in wastewater by using biodegradable microplastics to promote polyphosphorus bacteria, the polyphosphorus bacteria are one of Acinetobacter lwoffi and Accumulibacter.

[0010] As a preferred embodiment of the method for reducing phosphorus in wastewater by using biodegradable microplastics to promote polyphosphorus bacteria, the pretreatment is washing with sterilized water.

[0011] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, the biodegradable microplastics have a particle size of 1-3 mm and are in the form of round particles.

[0012] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, the mixed culture is carried out in an enrichment medium.

[0013] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, the enrichment medium comprises glucose, protein peptone, yeast powder, Na-glutamate, KH2PO4, (NH4)2SO4, and MgSO4·7H2O.

[0014] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, the culture is carried out on a shaker at 25-40°C and 120-180 r / min.

[0015] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, the culture is carried out for 3-5 days.

[0016] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, 0.5-1.5 g of biodegradable microplastics are added per 1×10 6

[0017] As a preferred scheme of the method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics, the container is a stainless steel ball with holes on the surface, and the hole diameter is 0.5-1.2 mm.

[0018] The present application has the following beneficial effects:

[0019] The phosphorus-accumulating ability of the phosphorus-accumulating bacteria is easily affected by the content of organic matter in wastewater. The biodegradable microplastics can provide additional carbon source for the phosphorus-accumulating bacteria and enhance the activity of the phosphorus-accumulating bacteria. The biodegradable microplastics are more easily attached by microorganisms. The addition of biodegradable microplastics can provide more attachment sites for the phosphorus-accumulating bacteria. By adjusting the type and particle size of the added biodegradable microplastics, the phosphorus-accumulating ability of the phosphorus-accumulating bacteria can be effectively improved. Compared with only adding the phosphorus-accumulating bacteria, the phosphorus removal rate is increased by 74.1% when the particle size of the polyhydroxyalkanoate PHA is 1 mm, effectively ensuring that the treated wastewater meets the phosphorus discharge standard. BRIEF DESCRIPTION OF DRAWINGS

[0020] ​In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings. Among them:

[0021] Figure 1 Phosphorus removal rate of microplastics with a particle size of 1 mm combined with phosphorus accumulating bacteria.

[0022] Figure 2 Phosphorus removal rate of microplastics with a particle size of 3 mm combined with phosphorus accumulating bacteria.

[0023] Figure 3 Culture medium schematic diagram of microplastics with a particle size of 1 mm combined with phosphorus accumulating bacteria.

[0024] Figure 4 Culture medium schematic diagram of microplastics with a particle size of 3 mm combined with phosphorus accumulating bacteria. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with the description of the embodiments.

[0026] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0027] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or alternative to other embodiments.

[0028] Preparation of enrichment medium:

[0029] 1) The raw materials are weighed according to the following formula: glucose 0.5g, peptone 0.5g, yeast powder 0.5g, Na-glutamate 0.5g, KH2PO40.5g, (NH4)2SO40.1g, MgSO4·7H2O 0.1g;

[0030] 2) Put the weighed raw materials into ultrapure water and stir until completely dissolved, then add ultrapure water to 1000mL, so that the PH is equal to 7.0;

[0031] 3) High pressure sterilization at 121℃ high temperature for 20 min to obtain the enrichment medium.

[0032] The calculation method of phosphorus removal rate is as follows:

[0033] The total phosphorus content in water is determined by ammonium molybdate spectrophotometry (GB11893-89), and the phosphorus removal rate is calculated.

[0034] Phosphorus removal rate = (A TP -B TP ) / A Tp * 100%; wherein, A TP is the total phosphorus content of the influent, B TP is the total phosphorus content of the effluent.

[0035] The phosphorus-accumulating small-month bacteria used in the application are purchased from Beijing Beinaelieliang Biotechnology Research Institute, and the number is BNCC337414.

[0036] The Acinetobacter lwoffii used in the application is purchased from Beijing Beinaelieliang Biotechnology Research Institute, and the number is BNCC139088.

[0037] The stainless steel ball used in the application has a diameter of 9 cm, and the pore size of the surface is 0.8 mm.

[0038] The total phosphorus content in the bioreactor of Changzhou Wunan Sewage Treatment Plant selected in the application is 10-15 mg / L, and the reactor runs normally after the stainless steel ball is put in.

[0039] The raw materials used in the application are commercially available in the art unless otherwise specified.

[0040] Example 1

[0041] The embodiment provides a method for promoting phosphorus-accumulating bacteria to reduce phosphorus elements in wastewater by using biodegradable microplastics.

[0042] 1) Select polyhydroxyalkanoic acid PHA with a particle size of 1 mm, and the particles are round, and wash 3 times with sterilized water;

[0043] 2) Take 10 6 phosphorus-accumulating small-month bacteria and 1 gram of polyhydroxyalkanoic acid PHA with a particle size of 1 mm, and add them to the enrichment medium, and culture at 30℃, 150r / min on a shaking table for 5 days, then fill the stainless steel ball;

[0044] 3) Put the stainless steel ball into the bioreactor of Changzhou Wunan Sewage Treatment Plant;

[0045] 4) Determine the total phosphorus content in the bioreactor, and calculate the phosphorus removal rate.

[0046] Example 2

[0047] The difference between this embodiment and embodiment 1 is that polyhydroxyalkanoate PHA is replaced by polylactic acid PLA, specifically:

[0048] 1) polylactic acid PLA with a particle size of 1 mm is selected, the particles are round, and the particles are washed with sterile water for 3 times;

[0049] 2) 10 6 accumulative phosphorus small months are mixed with 1 gram of polylactic acid PLA with a particle size of 1 mm and added to the enrichment medium, and after being cultured at 30°C and 150 r / min on a shaking table for 5 days, the stainless steel balls are filled;

[0050] 3) the stainless steel balls are put into the bioreactor of Changzhou Wunan sewage treatment plant;

[0051] 4) the total phosphorus content in the bioreactor is measured, and the phosphorus removal rate is calculated.

[0052] Embodiment 3

[0053] The difference between this embodiment and embodiment 1 is that polyhydroxyalkanoate PHA is replaced by polylactic acid PLA with a particle size of 3 mm, specifically:

[0054] 1) polylactic acid PLA with a particle size of 1 mm is selected, the particles are round, and the particles are washed with sterile water for 3 times;

[0055] 2) 10 6 accumulative phosphorus small months are mixed with 1 gram of polylactic acid PLA with a particle size of 3 mm and added to the enrichment medium, and after being cultured at 30°C and 150 r / min on a shaking table for 5 days, the stainless steel balls are filled;

[0056] 3) the stainless steel balls are put into the bioreactor of Changzhou Wunan sewage treatment plant;

[0057] 4) the total phosphorus content in the bioreactor is measured, and the phosphorus removal rate is calculated.

[0058] Embodiment 4

[0059] The difference between this embodiment and embodiment 1 is that the particle size of polyhydroxyalkanoate PHA is adjusted to 3 mm, specifically:

[0060] 1) polyhydroxyalkanoate PHA with a particle size of 3 mm is selected, the particles are round, and the particles are washed with sterile water for 3 times;

[0061] 2) 10 6 accumulative phosphorus small months are mixed with 1 gram of polyhydroxyalkanoate PHA with a particle size of 3 mm and added to the enrichment medium, and after being cultured at 30°C and 150 r / min on a shaking table for 5 days, the stainless steel balls are filled;

[0062] 3) Put the stainless steel balls into the bioreactor of Changzhou Wunan Sewage Treatment Plant;

[0063] 4) Measure the total phosphorus content in the bioreactor and calculate the phosphorus removal rate.

[0064] Example 5

[0065] This example is used to explore the influence of changing the type of bacteria on the phosphorus removal rate, specifically:

[0066] The phosphorus-accumulating Microcystis used in Examples 1-4 is replaced by Acinetobacter lwoffi.

[0067] Examples 1-5 are at least 5 groups of parallel tests, and the phosphorus removal rates of Examples 1-5 are recorded respectively, and the results are shown in Table 1.

[0068] Table 1

[0069]

[0070] According to the results in Table 1, it can be seen that the phosphorus removal rates achieved by the examples of the present application are very high, because biodegradable microplastics can provide additional carbon source for polyphosphorus bacteria, enhance their activity, and thus promote the progress of phosphorus removal. Especially when the particle size of polyhydroxyalkanoic acid PHA is 1 mm, the phosphorus removal rate can be as high as 62.3%. At the same time, biodegradable microplastics themselves have large specific surface area and pore structure, which is conducive to the attachment and growth of polyphosphorus bacteria, further improving the phosphorus removal efficiency. The phosphorus removal rate of Microcystis is better than that of Acinetobacter lwoffi, because Microcystis has higher activity and efficiency in the process of phosphorus removal. It can use polyphosphate compounds as endogenous carbon source, and convert them into inorganic phosphate through biochemical reaction, so as to realize the effect of phosphorus removal.

[0071] Comparative Example 1

[0072] Comparative Example 1 is based on Example 1, and the difference between Comparative Example 1 and Example 1 is that no polyhydroxyalkanoic acid PHA is added, specifically:

[0073] 1) Take 10 6 Microcystis and add them to the enrichment medium, and then fill them with stainless steel balls after culturing at 30°C and 150 r / min on a shaking table for 5 days;

[0074] 2) Put the stainless steel balls into the bioreactor of Changzhou Wunan Sewage Treatment Plant;

[0075] 3) Measure the total phosphorus content in the bioreactor and calculate the phosphorus removal rate.

[0076] Comparative Example 2

[0077] Comparative Example 2 is based on Example 1, and the difference between Comparative Example 2 and Example 1 is that polylactic acid PLA with a particle size of 5 mm is used, specifically:

[0078] 1) polylactic acid PLA with a particle size of 5 mm is selected, and the particles are round, and are washed with sterile water for 3 times;

[0079] 2) 10 6 accumulative phosphorus small months are mixed with 1 gram of polylactic acid PLA with a particle size of 5 mm and added to the enrichment medium, and after being cultured at 30°C and 150 r / min on a shaker for 5 days, they are filled with stainless steel balls;

[0080] 3) the stainless steel balls are put into the bioreactor of Changzhou Wunan Sewage Treatment Plant;

[0081] 4) the total phosphorus content in the bioreactor is measured, and the phosphorus removal rate is calculated.

[0082] Comparative Example 3

[0083] Comparative Example 3 is based on Example 1, and the difference between Comparative Example 3 and Example 1 is that the particle size of polyhydroxyalkanoate PHA is adjusted to 5 mm, specifically:

[0084] 1) polyhydroxyalkanoate PHA with a particle size of 5 mm is selected, and the particles are round, and are washed with sterile water for 3 times;

[0085] 2) 10 6 accumulative phosphorus small months are mixed with 1 gram of polyhydroxyalkanoate PHA with a particle size of 5 mm and added to the enrichment medium, and after being cultured at 30°C and 150 r / min on a shaker for 5 days, they are filled with stainless steel balls;

[0086] 3) the stainless steel balls are put into the bioreactor of Changzhou Wunan Sewage Treatment Plant;

[0087] 4) the total phosphorus content in the bioreactor is measured, and the phosphorus removal rate is calculated.

[0088] Comparative Example 4

[0089] Comparative Example 4 is used to explore the influence of changing the type of bacteria on the phosphorus removal rate, specifically:

[0090] The accumulative phosphorus small months used in Comparative Examples 2-3 are replaced with Acinetobacter lwoffi.

[0091] The phosphorus removal rates of Comparative Examples 1-4 are recorded and compared with Example 1, and the results are shown in Table 2.

[0092] Table 2

[0093]

[0094]

[0095] As can be seen from Table 2, compared with only adding phosphorus-accumulating small-month bacteria, the phosphorus removal rate is increased by 74.1% when the polyhydroxyalkanoate (PHA) with a particle size of 1 mm is added. This is because PHA, as a biodegradable plastic, has a large specific surface area, which can provide more attachment sites for polyphosphorus bacteria. In addition, small-particle-size microplastics are more easily utilized and decomposed by polyphosphorus bacteria, providing additional carbon sources, thereby enhancing the activity of polyphosphorus bacteria and promoting the phosphorus removal process. At the same time, PHA itself has a large specific surface area and pore structure, which is conducive to the attachment and growth of phosphorus-accumulating small-month bacteria, further improving the phosphorus removal efficiency. Compared with only adding phosphorus-accumulating small-month bacteria, when Acinetobacter lwoffi is used and polylactic acid (PLA) with a particle size of 5 mm is added, the phosphorus removal rate is decreased by 25%. This is because Acinetobacter lwoffi is not suitable for utilizing polylactic acid (PLA) as a carbon source for phosphorus removal. In addition, the 5 mm particle size of polylactic acid (PLA) has certain limitations for the attachment and utilization of Acinetobacter lwoffi, thereby leading to a decrease in the phosphorus removal rate. Therefore, the addition of PHA can improve the phosphorus removal efficiency of phosphorus-accumulating small-month bacteria and reduce pollutant emissions, which is of great significance for environmental protection.

[0096] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A method for promoting the reduction of phosphorus in wastewater by polyphosphorus bacteria using biodegradable microplastics, characterized by: Comprising, After the polyphosphorus bacteria are mixed with the pretreated biodegradable microplastics, they are loaded into a container and put into wastewater to reduce phosphorus elements in the wastewater; The biodegradable microplastics include one or both of polylactic acid (PLA) and polyhydroxyalkanoate (PHA); The polyphosphorus bacteria are one of Accumulibacter and Acinetobacter lwoffii; The pretreatment is washing with sterilized water; The biodegradable microplastics have a particle size of 1-3 mm and present as round particles; The mixed culture is in an enrichment medium; The enrichment medium includes glucose, protein peptone, yeast powder, Na-glutamate, KH2PO4, (NH4)2SO4, and MgSO4·7H2O; The culture is carried out on a shaker at 25-40 DEG C and 120-180 r / min; The culture time is 3-5 days; Each 1 x 10 6 Polyphosphorus bacteria need to add 0.5-1.5g biodegradable microplastics; The container is a stainless steel ball with holes on the surface, and the hole diameter is 0.5-1.2 mm.

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