A composite film and a preparation method and application thereof

Abstract

The present application relates to a kind of composite film and its preparation method and application.A kind of composite film, including water-impermeable layer and porous carrier layer;The porous carrier layer covers the surface of the water-impermeable layer;The porous carrier layer is mainly prepared from the following weight ratio of raw materials: polyethylene 40-70 parts, paraffin wax 15-40 parts, beneficial bacteria freeze-dried bacteria powder 0.5-6 parts.The composite film of the present application, water-impermeable layer can provide solid bottom layer for porous carrier layer, so that it is not easy to disintegrate in water, and can separate porous carrier layer and bottom mud, prevent pond water leakage, save water resources;At the same time, by making porous carrier layer contain beneficial bacteria, the content of beneficial bacteria in water body is guaranteed, the purification effect is more remarkable, and the water quality purification time is more persistent, does not need to frequently supplement strain, saves labor and breeding cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water purification, in particular to a composite membrane and a preparation method and application thereof. BACKGROUND

[0002] In order to meet the increasing demand of residents for aquatic products, the intensive aquaculture in China has developed rapidly. However, the intensive aquaculture exceeds the ecological regulation capacity of the aquaculture water body, and the organic matter such as residual feed, feces and carcasses at the bottom of the pond accumulates and is converted into toxins such as ammonia nitrogen, nitrite and hydrogen sulfide, which often causes diseases and even death of aquatic animals, leading to failure of aquaculture and seriously affecting the sustainable, healthy and steady development of the aquaculture industry. Therefore, improving the environment at the bottom of the pond and purifying the water quality are of great significance to improve the aquaculture environment and maintain the sustainability of the aquaculture.

[0003] There are various beneficial bacteria in nature, such as Bacillus subtilis, Bacillus licheniformis, lactic acid bacteria, yeast and Rhodopseudomonas palustris, which have the effects of improving the aquaculture environment and promoting the growth and development of aquatic animals. If two or more than two beneficial bacteria without antagonistic effect are mixed to form a composite bacteria, each strain has a more obvious effect through functional synergistic complementation compared with a single strain. The composite bacteria have multiple functions such as purifying the aquaculture water quality, inhibiting harmful pathogens, enhancing the immunity of animals and reducing the stress response.

[0004] The immobilized microorganism technology is a new type of biological engineering technology that uses physical or chemical means to confine free microorganisms in a specific area, so that they can be densely concentrated with high biological activity and can be used continuously. Due to its advantages such as easy separation and no harm to organisms, it has been widely used in enzyme catalysis, biological fermentation and other fields. The porous carrier contains rich microporous structure and has large specific surface area, which can adsorb a large amount of beneficial bacteria on the surface and inside of the carrier, and the suspended solid particles in the water body can also be gathered on the surface of the carrier. With the accumulation of suspended solid particles and the continuous growth and enrichment of beneficial bacteria, it is beneficial to the growth and reproduction of composite bacteria, forming a high-density biological catalyst, which can greatly increase the concentration of microorganisms at the bottom of the pond, thereby decomposing the organic matter such as residual feed, feces and carcasses at the bottom of the pond, removing toxins such as ammonia nitrogen, nitrite and hydrogen sulfide in the water body, maintaining the purification of the aquaculture water body for a long time, preventing the chronic harm of toxic substances such as ammonia nitrogen, nitrite and hydrogen sulfide to aquatic animals, and improving the success rate of aquaculture.

[0005] However, the existing microbial preparations are in the form of liquid, powder and solid particles, which need to be pretreated by manual labor before being poured or mixed with materials in the whole pond, which is time-consuming and labor-intensive. Moreover, the water purification effect is maintained for a short time, and the beneficial bacteria content in the aquaculture water body needs to be supplemented regularly and frequently to maintain good water purification effect.

[0006] Therefore, it is urgent to develop a breeding water body probiotic supplement method which can effectively purify water quality, has long-lasting purification effect and is convenient and efficient. SUMMARY

[0007] Therefore, it is necessary to provide a composite film in view of the problems of time-consuming and laborious, short maintenance time of purification effect of the existing microbial preparation form in the application of aquaculture water purification.

[0008] A composite film comprises a water-impermeable layer and a porous carrier layer; the porous carrier layer covers the surface of the water-impermeable layer.

[0009] The porous carrier layer is mainly prepared from the following raw materials in parts by weight: polyethylene 40-70 parts, paraffin 15-40 parts, and beneficial bacteria freeze-dried bacteria powder 0.5-6 parts.

[0010] The water-impermeable layer can provide a solid bottom layer for the porous carrier layer, so that the porous carrier layer is not easy to disintegrate in water, and the porous carrier layer can be separated from the bottom mud to prevent pond water leakage and save water resources. At the same time, the porous carrier layer contains beneficial bacteria, which ensures the content of beneficial bacteria in the water body, the purification effect is more significant, and the water quality purification time is more persistent, so that the labor and breeding cost are saved.

[0011] In one embodiment, the porous carrier layer further comprises the following raw materials in parts by weight: polyvinyl alcohol 0-18 parts, pore-forming agent 0-14 parts, auxiliary agent 0-5 parts, and acidic crosslinking agent 65-95 parts. The crosslinking reaction between polyvinyl alcohol and the acidic crosslinking agent can improve the porosity of the porous carrier.

[0012] In one embodiment, the water-impermeable layer is a geomembrane; the polyethylene is low-density polyethylene; the pore-forming agent is at least one of crude oil and calcium carbonate; the auxiliary agent is polyquaternary ammonium salt-10; and the acidic crosslinking agent is at least one of maleic acid, citric acid, boric acid, oxalic acid, trimellitic anhydride, 1.6 adipic acid, and phthalic anhydride.

[0013] It is found in the research that crude oil itself contains gasoline components of different distillation ranges. At a suitable temperature, gasoline volatilizes to form a large number of pores, and crude oil itself contains a large amount of trace elements, which is conducive to the growth and reproduction of beneficial bacteria. A large amount of carbon dioxide is generated after the reaction of calcium carbonate and the acidic crosslinking agent, which can improve the porosity of the porous carrier. Polyquaternary ammonium salt-10 as an auxiliary agent can improve the hydrophilic property of the surface of the porous carrier, which is more conducive to microbial biofilm formation.

[0014] In one embodiment, the geomembrane is a high-density polyethylene geomembrane.

[0015] The porous carrier layer is prepared from the following raw materials in parts by weight: low-density polyethylene 45-65 parts, paraffin 17-35 parts, polyvinyl alcohol 2-16 parts, crude oil 4-6 parts, calcium carbonate 1.5-5 parts, polyquaternary ammonium salt-10 2-5 parts, and beneficial bacteria freeze-dried bacteria powder 1-6 parts, and boric acid 70-90. Compared with traditional porous materials (such as activated carbon, activated alumina, polyethylene, ceramic, zeolite, and the like), the composite film of the present application can more effectively immobilize the beneficial bacteria.

[0016] In one embodiment, the beneficial bacteria freeze-dried bacteria powder comprises at least one of Bacillus subtilis freeze-dried bacteria powder, Bacillus licheniformis freeze-dried bacteria powder, and Enterococcus faecalis freeze-dried bacteria powder.

[0017] The number of viable bacteria in the beneficial bacteria freeze-dried bacteria powder is 1.0-4.0 x 10 11 cfu / g.

[0018] In one embodiment, the number of viable bacteria in the beneficial bacteria freeze-dried bacteria powder is 2.0-4.0 x 10 11 cfu / g.

[0019] The Bacillus subtilis freeze-dried bacteria powder contains 50-70 wt% of Bacillus subtilis, the Bacillus licheniformis freeze-dried bacteria powder contains 25-35 wt% of Bacillus licheniformis, and the Enterococcus faecalis freeze-dried bacteria powder contains 5-15 wt% of Enterococcus faecalis.

[0020] In one embodiment, the water-impermeable layer has a thickness of 0.2-5.0 mm, the porous carrier layer has a thickness of 0.2-10.0 mm, the porous carrier has a pore size of 4-10 μm, a specific surface area of 100-200 m 2 / g, and a porosity of 80-90%; and the water-impermeable layer and the porous carrier layer are integrally bonded by high-impact polystyrene glue.

[0021] It has been found in research that, in the pore size distribution of a carrier for immobilizing microorganisms, generally 70% of the pore sizes should be greater than the minimum size of the microorganisms and less than 5 times the maximum size of the microorganisms. The pore size of the porous carrier layer in the composite film of the present application meets the growth requirements of the composite beneficial bacteria, and provides a good growth attachment surface for the growth of the beneficial bacteria. The higher porosity and larger specific surface area provide more space for the growth and reproduction of the beneficial bacteria in the interior of the porous carrier.

[0022] In one embodiment, the melting point of the paraffin is 55-70°C.

[0023] In one embodiment, the melting point of the paraffin is 60-65°C.

[0024] The application further provides a preparation method of the composite film, comprising the following steps:

[0025] Preparation of the molten component: weighing raw materials, mixing, heating, and obtaining the molten component;

[0026] Adding beneficial bacteria: adding the freeze-dried bacteria powder of the beneficial bacteria into the molten component to obtain the molten component containing the beneficial bacteria;

[0027] Preparation of the composite film: covering the molten component containing the beneficial bacteria on the water-impermeable layer to obtain the composite film.

[0028] In one of the embodiments, the step of preparing the molten component is specifically as follows: weighing raw materials, mixing, adding into a furnace, heating to 110-120 DEG C, stirring uniformly, continuously heating until no oil gas is distilled, and obtaining the molten component;

[0029] The step of adding the beneficial bacteria is specifically as follows: cooling the obtained molten component to 70 DEG C, adding the freeze-dried bacteria powder of the beneficial bacteria, and stirring to obtain the molten component containing the beneficial bacteria;

[0030] The step of preparing the composite film is specifically as follows: laying the water-impermeable layer on the composite film substrate, spraying glue on the water-impermeable layer, pouring the molten component containing the beneficial bacteria, adding the acidic crosslinking agent into the molten component containing the beneficial bacteria to generate crosslinking reaction, and taking out the composite film after immobilization to obtain the composite film.

[0031] The application further provides application of the composite film in water purification and / or aquaculture.

[0032] Compared with the prior art, the application has the following beneficial effects:

[0033] The composite film of the present application can provide a solid bottom layer for the porous carrier layer, so that the porous carrier layer is not easy to disintegrate in water, and can be separated from the bottom mud to prevent pond water leakage and save water resources; meanwhile, the porous carrier layer contains beneficial bacteria, so that the bacterial content of the water body is ensured, the purification effect is more remarkable, the water quality purification time is more persistent, and the labor is saved without frequent replenishment of bacterial strains; the cross-linking reaction between polyvinyl alcohol and the acidic cross-linking agent can improve the porosity of the porous carrier. Crude oil itself contains gasoline components of different distillation ranges, and at a suitable temperature, gasoline volatilization can form a large number of pores, and crude oil itself contains a large amount of trace elements, which is conducive to the growth and reproduction of beneficial bacteria; a large amount of carbon dioxide is generated after the reaction of calcium carbonate and the acidic cross-linking agent, which can improve the porosity of the porous carrier; the use of polyquaternium-10 as an additive can improve the hydrophilic property of the surface of the porous carrier, and is more conducive to microbial biofilm formation. Compared with traditional porous materials (such as activated carbon, activated alumina, polyethylene, ceramics, zeolite and the like), the composite film of the present application can more effectively immobilize beneficial bacteria. The pore size of the porous carrier layer in the composite film of the present application meets the growth needs of the contained composite beneficial bacteria, and provides a good growth and adhesion surface for the contained beneficial bacteria. The higher porosity and larger specific surface area can provide more space for the growth and reproduction of beneficial bacteria in the interior of the porous carrier.

[0034] The composite film of the present application contains beneficial bacteria in the porous carrier layer, which can provide beneficial bacteria for the aquaculture water body for a long time, increase the content of beneficial bacteria in the water body, quickly decompose the organic matter at the bottom of the pond, quickly reduce toxic substances such as ammonia nitrogen, nitrite and hydrogen sulfide, maintain the purification of the aquaculture water body for a long time, prevent the chronic harm of toxic substances such as ammonia nitrogen, nitrite and hydrogen sulfide to aquatic animals, and can also reduce manual operation, material consumption and aquaculture cost, and improve the success rate of aquaculture.

[0035] The preparation method of the composite film of the present application is simple and easy to implement, and is suitable for large-scale promotion. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present application, the present application will be described more fully below. The present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0038] The reagents used in the following examples, unless otherwise specified, are commercially available; the methods used in the following examples, unless otherwise specified, are routinely achievable.

[0039] Example 1

[0040] Preparation of the composite film (thickness of the water-impermeable layer: 0.2 mm, thickness of the porous carrier layer: 0.2 mm).

[0041] Raw materials and proportions: low-density polyethylene 63 parts, paraffin wax with a melting point of 62°C 34 parts, polyvinyl alcohol 2 parts, beneficial bacteria freeze-dried bacteria powder 1 part, boric acid 80 parts; high-density polyethylene geomembrane with a thickness of 0.2 mm.

[0042] Preparation method:

[0043] Preparation of the beneficial bacteria freeze-dried bacteria powder: Bacillus subtilis, Bacillus licheniformis, and Enterococcus faecalis selected from pond mud were used as the bacterial source, and enrichment culture was performed according to a conventional method. After enrichment, the bacterial suspension was concentrated and freeze-dried to obtain freeze-dried bacteria powder containing 60 wt% of Bacillus subtilis, freeze-dried bacteria powder containing 30 wt% of Bacillus licheniformis, and freeze-dried bacteria powder containing 10 wt% of Enterococcus faecalis. The three kinds of freeze-dried bacteria powder obtained above were mixed to obtain beneficial bacteria freeze-dried bacteria powder containing 3.0 x 10 11 cfu / g of effective viable bacteria;

[0044] Preparation of the molten component: the raw materials low-density polyethylene and paraffin wax were weighed according to the above proportions, mixed, and then added to a melting furnace. After heating to 110°C, stirring was performed at 120 rpm for 10 minutes. The temperature was continuously maintained at 110°C until no more oil gas was distilled out, and the molten component was obtained.

[0045] Addition of the beneficial bacteria: the molten component above was cooled to 70°C, and the beneficial bacteria freeze-dried bacteria powder weighed according to the above proportions was added. Stirring was performed at 180 rpm for 1 minute to obtain the molten component containing the beneficial bacteria.

[0046] Preparation of the composite film: the high-density polyethylene geomembrane was evenly laid on the composite film substrate, and high-impact polystyrene glue was sprayed on the high-density polyethylene geomembrane. The molten component containing the beneficial bacteria above was immediately poured onto the high-impact polystyrene glue, and the thickness was 0.2 mm.

[0047] A saturated boric acid solution prepared using the above proportions of boric acid was added to the molten component containing the beneficial bacteria, and the pH was adjusted to 8 after standing for 1 h. Crosslinking was performed for 4 h. After immobilization was completed, the composite film was taken out, and the residual substances on the surface of the composite film were washed clean. The composite film was dried in a clean environment to obtain the product.

[0048] Example 2

[0049] Preparation of the composite membrane (thickness of the water-impermeable layer: 3.0 mm, thickness of the porous carrier layer: 5.0 mm).

[0050] Raw materials and proportions: 55 parts of low-density polyethylene, 25 parts of paraffin wax with a melting point of 62°C, 8 parts of polyvinyl alcohol, 5 parts of crude oil, 1.5 parts of calcium carbonate, 3 parts of polyquaternary ammonium salt-10, and 3 parts of beneficial bacteria powder, 90 parts of boric acid; high-density polyethylene geomembrane with a thickness of 3.0 mm.

[0051] Preparation method:

[0052] Preparation of the beneficial bacteria freeze-dried bacteria powder: Bacillus subtilis, Bacillus licheniformis, and Enterococcus faecalis were used as the bacterial source, which were screened from pond mud. According to the conventional method, the bacteria were respectively enriched and cultured, and the bacterial suspension obtained after enrichment was concentrated and freeze-dried to obtain a freeze-dried bacteria powder containing 60 wt% of Bacillus subtilis, a freeze-dried bacteria powder containing 30 wt% of Bacillus licheniformis, and a freeze-dried bacteria powder containing 10 wt% of Enterococcus faecalis. The three freeze-dried bacteria powders were mixed to obtain a freeze-dried bacteria powder containing 3.0 x 10 11 cfu / g of beneficial bacteria;

[0053] Preparation of the molten component: the raw materials, i.e., low-density polyethylene, paraffin wax, polyvinyl alcohol, crude oil, calcium carbonate, and polyquaternary ammonium salt-10, were weighed according to the above-mentioned proportions, mixed, and then added to a melting furnace. The mixture was heated to 120°C and stirred at 200 rpm for 60 minutes. The heating was continued (so that the temperature was maintained at 120°C) until no oil gas was distilled out, and the molten component was obtained.

[0054] Addition of the beneficial bacteria: the molten component was cooled to 70°C, and the freeze-dried bacteria powder weighed according to the above-mentioned proportions was added. The mixture was stirred at 240 rpm for 3 minutes.

[0055] Preparation of the composite membrane: the high-density polyethylene geomembrane was evenly laid on the composite membrane substrate, and high-impact polystyrene glue was sprayed on the high-density polyethylene geomembrane. The molten component containing the beneficial bacteria was immediately poured onto the high-impact polystyrene glue, and the thickness of the composite membrane was 5.0 mm.

[0056] A saturated boric acid solution prepared by using the boric acid according to the above-mentioned proportions was added to the molten component containing the beneficial bacteria, and the mixture was allowed to stand for 4 hours. The pH value was adjusted to 10, and the mixture was crosslinked for 24 hours. After the immobilization was completed, the composite membrane was taken out, and the residual substances on the surface of the composite membrane were washed off. The composite membrane was dried in a clean environment, and the composite membrane was obtained.

[0057] Example 3

[0058] Preparation of the composite membrane (thickness of the water-impermeable layer: 5.0 mm, thickness of the porous carrier layer: 10.0 mm).

[0059] Raw materials and proportions: 47 parts of low-density polyethylene, 17 parts of paraffin wax with a melting point of 62℃, 16 parts of polyvinyl alcohol, 5 parts of crude oil, 4 parts of calcium carbonate, 5 parts of polyquaternary ammonium salt-10, 6 parts of beneficial bacteria powder, and 70 parts of boric acid; a high-density polyethylene geomembrane with a thickness of 5.0 mm.

[0060] Preparation method:

[0061] Preparation of beneficial bacteria freeze-dried bacteria powder: Bacillus subtilis, Bacillus licheniformis, and Enterococcus faecalis screened from pond mud were used as the bacterial source. According to the conventional method, the bacteria were enriched and cultured, and the bacterial suspension obtained after enrichment was concentrated and freeze-dried to obtain freeze-dried bacteria powder containing 60wt% of Bacillus subtilis, freeze-dried bacteria powder containing 30wt% of Bacillus licheniformis, and freeze-dried bacteria powder containing 10wt% of Enterococcus faecalis. The three kinds of freeze-dried bacteria powder obtained above were mixed to obtain beneficial bacteria freeze-dried bacteria powder containing 3.0×10 11 cfu / g of effective viable bacteria;

[0062] Preparation of molten ingredients: The raw materials, low-density polyethylene, paraffin wax, polyvinyl alcohol, crude oil, calcium carbonate, and polyquaternary ammonium salt-10, were weighed according to the above proportions, mixed, and then added to a melting furnace. The mixture was heated to 115℃ and stirred at 160rpm for 30 minutes. The temperature was maintained at 115℃ by continuous heating until no oil gas was distilled out, and the molten ingredients were obtained.

[0063] Addition of beneficial bacteria: The molten ingredients above were cooled to 70℃, and the beneficial bacteria freeze-dried bacteria powder weighed according to the above proportions was added. The mixture was stirred at 210rpm for 2 minutes.

[0064] Preparation of the composite membrane: The high-density polyethylene geomembrane was evenly laid on the composite membrane substrate, and high-impact polystyrene glue was sprayed on the high-density polyethylene geomembrane. The molten ingredients containing beneficial bacteria above were immediately poured onto the high-impact polystyrene glue, and the thickness was 10mm.

[0065] A saturated boric acid solution prepared with the above proportions of boric acid was added to the molten ingredients containing beneficial bacteria, and the mixture was allowed to stand for 2.5h. The pH was adjusted to 9, and the crosslinking was carried out for 14h. After the immobilization was completed, the composite membrane was taken out, and the residual substances on the surface of the composite membrane were washed off. The composite membrane was dried in a clean environment to obtain the final product.

[0066] Experimental Example 1

[0067] According to the conventional method, the pore size, specific surface area, and porosity of the porous carrier layer of the composite membrane prepared in Examples 1-3 were measured using a specific surface area and pore size analyzer and a porosity tester.

[0068] Measurement results:

[0069] (1) The pore size of the porous carrier of the composite film prepared in Example 1 is 6-8 μm, the specific surface area is 100 m2 / g, and the porosity is 80%; 2

[0070] (2) The pore size of the porous carrier of the composite film prepared in Example 2 is 4-10 μm, the specific surface area is 200 m2 / g, and the porosity is 90%; 2

[0071] (3) The pore size of the porous carrier of the composite film prepared in Example 3 is 5-9 μm, the specific surface area is 100 m2 / g, and the porosity is 85%; 2

[0072] Experimental Example 2

[0073] The application effects of the composite films prepared in Examples 1-3 were verified.

[0074] Experimental method: The composite films prepared in Examples 1-3 were respectively laid on the bottom of 2x2 mu of earth pond, 80,000 shrimp seedlings per mu were put in for cultivation, as experimental ponds; HDPE geomembrane (purchased from Guangzhou Xijia E-commerce Company) was laid as a blank control. In the cultivation process, the experimental ponds did not put beneficial bacteria freeze-dried bacteria powder; the blank control pond was sprayed with 50 g of beneficial bacteria freeze-dried bacteria powder with 3.0x10 11 cfu / g of effective viable bacteria number every 2 weeks. After 90 days, the water body bacillus, fecal enterococcus viable content and ammonia nitrogen, nitrite, hydrogen sulfide content were measured.

[0075] Experimental results: As shown in Tables 1, 2 and 3, the use of the composite film prepared in the application increases the content of bacillus and enterococcus faecalis in the pond water, reduces the toxic and harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide in the water body, and improves the survival rate and cultivation success rate of prawns, especially the composite film prepared in Example 2, the effect is better. It is proved that the composite film prepared in the application can more effectively prevent the chronic harm of toxic and harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide to aquatic organisms compared with the prior art, and can improve the survival rate and cultivation success rate of aquatic organisms.

[0076] Table 1 Application effect of the composite film prepared in Example 1

[0077] Experimental pond Blank pond Ammonia nitrogen 0.1 mg / L 2.5 mg / L Nitrite 0.05 mg / L 1.2 mg / L Hydrogen sulfide 0.001 mg / L 0.5 mg / L Bacillus 1.6 x 10 6 CFU / mL 1.1 x 10 4 CFU / mL Enterococcus faecalis 1.2 x 10 6 CFU / mL 1.3 x 10 4 CFU / mL Shrimp survival rate 88.0％ 52.0％

[0078] Table 2 Application effect of the composite film prepared in Example 2

[0079]

[0080]

[0081] ​​​Table 3 Application effects of the composite films prepared in Example 3

[0082] Experimental pond Blank pond Ammonia nitrogen 0.05 mg / L 2.5 mg / L Nitrite 0.005 mg / L 1.2 mg / L Hydrogen sulfide 0.004 mg / L 5 mg / L Bacillus 2.0 x 10 6 CFU / mL 1.1 x 10 4 CFU / mL Enterococcus faecalis 2.2 x 10 6 CFU / mL 1.3 x 10 4 CFU / mL Shrimp survival rate 90％ 52.0％

[0083] The technical features of the above-described embodiments can be combined in any manner. For the sake of brevity, not all possible combinations are described, but it should be understood that the scope of the present disclosure encompasses all such possible combinations.

[0084] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but should not be understood as a limitation on the scope of the patent. It should be pointed out that, for those skilled in the art, some modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a composite film, characterized by, The composite film comprises a water-impermeable layer and a porous carrier layer; the porous carrier layer covers the surface of the water-impermeable layer; The preparation method of the composite film comprises the following steps: Preparation of a molten component: 45-65 parts of low-density polyethylene, 17-35 parts of paraffin, 2-16 parts of polyvinyl alcohol, 4-6 parts of crude oil, 1.5-5 parts of calcium carbonate, and 2-5 parts of polyquaternary ammonium salt-10 are weighed and mixed, then added to a furnace, heated to 110-120℃, stirred uniformly, and continuously heated until no oil gas is distilled, to obtain a molten component; Adding beneficial bacteria: the molten component is cooled to 70℃, 1-6 parts of beneficial bacteria freeze-dried powder is added, and stirred to obtain a molten component containing beneficial bacteria; Preparation of a composite film: a water-impermeable layer is laid on a composite film substrate, glue is sprayed on the water-impermeable layer, and then the molten component containing beneficial bacteria is poured; 70-90 parts of boric acid is added to the molten component containing beneficial bacteria to undergo cross-linking reaction; after immobilization, the composite film is taken out, and the preparation of the composite film is completed; the water-impermeable layer is a high-density polyethylene geomembrane; the water-impermeable layer and the porous carrier layer are integrally bonded by high-impact polystyrene glue.

2. The production method according to claim 1, characterized by, The beneficial bacteria freeze-dried powder comprises at least one of Bacillus subtilis freeze-dried powder, Bacillus licheniformis freeze-dried powder, and Enterococcus faecalis freeze-dried powder; The effective viable bacteria number in the freeze-dried bacteria powder of the beneficial bacteria is 1.0-4.0×10 11 cfu / g.

3. The preparation method according to claim 2, characterized in that, The effective viable bacteria number in the freeze-dried bacteria powder of the beneficial bacteria is 2.0-4.0 x 10 11 cfu / g; The Bacillus subtilis freeze-dried powder contains 50-70wt% of Bacillus subtilis, the Bacillus licheniformis freeze-dried powder contains 25-35wt% of Bacillus licheniformis, and the Enterococcus faecalis freeze-dried powder contains 5-15wt% of Enterococcus faecalis.

4. The method of claim 1, wherein, The water-impermeable layer has a thickness of 0.2-5.0 mm; the porous carrier layer has a thickness of 0.2-10.0 mm; the porous carrier has a pore size of 4-10 μm, a specific surface area of 100-200 m 2 / g, and a porosity of 80-90%.

5. Application of the composite film prepared by the preparation method of any one of claims 1-4 in water purification and / or aquaculture.

Images