Preparation method of a bioaugmentation flexible carrier and application thereof

Abstract

This invention discloses a method for preparing and applying a bio-enhanced flexible carrier. The aim is to obtain a bio-friendly carrier that can rapidly attach biofilms, support plant growth, and enhance the aquatic ecological structure, belonging to the field of water purification and ecological restoration. The steps are as follows: First, bio-based materials such as loofah sponges and hemp nets are immersed in a composite calcium cross-linked chitosan solution of a certain concentration for reaction. Then, sodium hydroxide solution is added to adjust the pH to 6.8-8.0, allowing the composite calcium cross-linked chitosan to form a cationic film on the surface of the bio-based material. After drying, the unadhered chitosan on the outer layer is rinsed off with water, and dried again to obtain the flexible carrier. Submerged plants are then attached to the flexible carrier, and specific bacterial species can be selected and attached to the flexible carrier according to the water quality characteristics. Finally, the carrier is bound into an ellipsoidal packing material (in series), which is the bio-enhanced flexible carrier. The bio-enhanced flexible carrier prepared by this invention is environmentally friendly, inexpensive, has a fast biofilm attachment rate, and significantly removes pollutants, thus promoting the ecological health of aquatic bodies.

Description

Technical Field

[0001] This invention is applicable to the fields of water purification and aquatic ecosystem restoration, specifically relating to the preparation and application of a bio-enhanced flexible carrier. Background Technology

[0002] my country's unique topography and diverse climate have resulted in a large number and wide distribution of small rivers, lakes, and reservoirs. These water bodies have slow flow rates and are easily disturbed by external factors, with most being slow-flowing water bodies. Therefore, the effective removal of pollutants from slow-flowing water bodies and the restoration of their aquatic ecological structures are of great significance to the ecological construction of my country's water environment.

[0003] Currently, artificial aquatic plants and ecological floating islands have been widely recognized and applied for in-situ treatment of slow-flowing water bodies. Among them, artificial aquatic plants, as a biofilm technology, use some corrosion-resistant materials and utilize microorganisms to attach and grow on the surface of the carrier to form a biofilm. Through the metabolic activities of microorganisms, pollutants are absorbed and transformed. Ecological floating islands utilize the principle of soilless cultivation. Not only can aquatic plants planted on the carrier remove pollutants, but also plant roots can provide a living environment for microorganisms to form a biofilm to purify water quality. However, the above-mentioned remediation technologies also have some problems: (1) Commonly used carrier materials such as carbon fiber often generate a large amount of waste during production. Basalt fiber has high manufacturing costs and is heavy, making it inconvenient to transport and install. Polyethylene, polyvinyl chloride and other high molecular polymers have poor hydrophilicity, resulting in a long biofilm formation period and difficulty in degradation, which can easily cause secondary pollution. (3) Biofilms formed on conventional carriers often have reduced activity due to a lack of sufficient carbon sources. (2) Ecological floating islands rely only on the action of plant roots and their microorganisms, which mainly have a purifying effect on the upper water body. The increase in biomass and water quality purification of deep water bodies need to be strengthened.

[0004] Therefore, exploring efficient and low-consumption water ecological restoration technologies to restore slow-flowing water bodies to their proper ecological functions as soon as possible is a key technical problem that urgently needs to be solved. Hemp and loofah sponges, as bio-based materials, are abundant renewable resources worldwide, environmentally friendly, and inexpensive. Loofah sponges possess a unique network structure and good biocompatibility, providing favorable conditions for plant anchorage and microbial attachment. Simultaneously, bio-based materials can also serve as slow-release carbon sources, promoting rapid microbial attachment and growth, and accelerating biofilm formation. However, while hemp and loofah sponges appear to be ideal carrier materials, they also have drawbacks such as poor corrosion resistance. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing an environmentally friendly, rapidly biofilm-forming, plant-supporting, and aquatic ecological-enhancing flexible carrier.

[0006] This invention proposes a method for preparing and applying a bio-reinforced flexible carrier. First, bio-based materials such as loofah sponges and hemp netting are immersed in a composite calcium-crosslinked chitosan solution of a certain concentration for reaction. Then, sodium hydroxide alkali solution is added to adjust the pH to 6.8-8.0, causing the composite calcium-crosslinked chitosan to form a cationic film on the surface of the bio-based materials. After drying, the unadhered chitosan on the outer layer is rinsed off with water, and after drying again, a flexible carrier is obtained. Submerged plants are planted on the flexible carrier, and specific bacterial species can be selected and attached to the flexible carrier according to the water quality characteristics. Finally, the carrier is bound into an ellipsoidal packing material (in series), which is the bio-reinforced flexible carrier.

[0007] Step 1: Preparation of a flexible carrier

[0008] The bio-based material is immersed in a composite calcium cross-linked chitosan solution and reacted for a certain period of time. Sodium hydroxide alkaline solution is added to adjust the pH to 6.8-8.0 and the mixture is left to stand for a period of time to allow the composite calcium cross-linked chitosan to form a cationic film on the surface of the bio-based material. After drying, the outer layer of unadhered chitosan is rinsed off with water and dried again to obtain a flexible carrier.

[0009] In the technical implementation of this invention, the bio-based material is a plant fiber material such as loofah sponge or hemp net.

[0010] In the technical embodiment of the present invention, the method for preparing the composite calcium cross-linked chitosan solution is as follows: chitosan is slowly added to an acetic acid solution and stirred to dissolve. After the added chitosan is completely dissolved, calcium chloride is added, and the mixture is stirred again until completely dissolved to obtain the composite calcium cross-linked chitosan solution. The acetic acid solution is a 1-2% dilute acetic acid solution, and the mass ratio of chitosan to calcium chloride is 3:1-8:1. The composite calcium cross-linked chitosan solution contains 0.2-1.5% chitosan.

[0011] In the technical embodiments of the present invention, the reaction time of the bio-based material immersed in the composite calcium cross-linked chitosan solution is 3-5 h; the concentration of the sodium oxide alkaline solution is 2 mol / L; the standing time is 15-60 min; and the drying temperature is 30-70℃.

[0012] Step 2: Preparation of a bio-enhanced flexible carrier

[0013] Submerged plants are planted on a flexible carrier, and specific bacterial species can be selected and attached to the flexible carrier according to the water quality characteristics. Finally, they are tied into an ellipsoidal packing material (in series), which is a bio-enhanced flexible carrier.

[0014] In the technical implementation of the present invention, the submerged plants are seeds, spores or seedlings of submerged plants such as Hydrilla verticillata, Ceratophyllum demersum, Vallisneria natans, Potamogeton malaianus, Potamogeton crispus, and Myriophyllum spicatum; the submerged plants are fixed by wrapping the spores or roots of the submerged plants in the holes of a flexible carrier, or by fixing the seeds of the submerged plants in a flexible carrier, so that the roots of the plants can grow out through the holes.

[0015] Furthermore, in the technical embodiments of the present invention, the bacterial strains are conventional water treatment strains such as denitrification and phosphorus removal strains; the bacterial strain loading is carried out by placing a flexible carrier in a composite bacterial culture solution composed of one or more bacterial strains and culturing it for 3-6 days. During this period, continuous aeration is maintained to control the DO concentration in the culture solution to 2-4 mg / L, and ammonia nitrogen and nitrate nitrogen are added daily. When a large amount of light yellow deposits form on the surface of the flexible carrier, the bacterial strain loading can be considered successful. Finally, the carrier is rinsed with slow water; the culture solution mainly contains appropriate amounts of carbon, nitrogen, phosphorus, and essential trace elements.

[0016] Compared with existing water treatment carrier devices, the bio-enhanced flexible carrier of the present invention has the following advantages:

[0017] 1. The flexible carrier used in this invention is composed of bio-based materials such as hemp and loofah sponge, which are environmentally friendly and inexpensive, possessing a unique network structure, large specific surface area, and good biocompatibility. Furthermore, through cationic coating modification, it can both improve the biofilm formation rate and extend the carrier's service life. Even if the flexible carrier breaks down, it can still purify water as an independent unit, without causing secondary pollution.

[0018] 2. The flexible carrier used in this invention can serve as a solid slow-release carbon source, adapting to the characteristics of low carbon-nitrogen ratio in slow-flowing water bodies. The carbon source it decomposes can promote the growth and reproduction of microorganisms in the system, improve biological activity, and enhance the denitrification effect.

[0019] 3. In this invention, specific bacterial species can be attached to a flexible carrier according to the water quality characteristics, which can enhance the removal effect of pollutants and create favorable conditions for the formation of biofilm on the carrier and the growth of submerged plants, thereby promoting the structural integrity of the aquatic ecosystem.

[0020] 4. In this invention, when the carrier is placed in sewage, the submerged plants, bacteria, etc. that are colonized or attached can form a stable biological community with the "native" microorganisms and algae that quickly attach to the raw water, thereby exerting a combined removal effect of bacteria-algae-plants and enhancing the purification effect. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the bio-enhanced flexible carrier in the embodiment.

[0023] Figure 2 To assess the removal efficiency of various pollutants by bio-enhanced flexible carriers.

[0024] In the diagram: 1- Submerged plant; 2- Bioreinforced flexible carrier structural unit; 3- Flexible carrier with submerged plant attached; 4, 5- Flexible carrier with attached microbial strains. Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0026] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to. Example

[0030] The preparation and application of a bio-enhanced flexible carrier includes the following steps:

[0031] (1) The jute net is made of jute fiber rope with a mesh size of 4 mm. After washing the mature and peeled dried loofah sponge, take it out and dry it.

[0032] (2) Weigh 10 g of chitosan and add it to 2000 mL of 1% acetic acid. Stir electromagnetically for 3 h to completely dissolve it. Then add 4 g of CaCl2 and stir thoroughly to dissolve. Immerse the washed hemp mesh and loofah sponge in the chitosan solution and soak for 40 min. Add 2 M NaOH solution to adjust the pH to 7.5. Stir gently to allow the chitosan on the loofah sponge and hemp mesh to gradually solidify. After 20 min, remove and dry at 35℃. Wash with ultrapure water until neutral and dry for later use to obtain a flexible carrier.

[0033] (3) Add 16 mg of nitrifying bacteria and denitrifying bacteria, along with nutrient solution, to 800 mL of simulated wastewater. After thorough stirring and standing for 30 min, place the flexible carrier loofah sponge into the compound bacterial culture solution, stir evenly, and then place it in a 25℃ constant temperature water bath. Cover with plastic wrap and continuously aerate, controlling the DO concentration of the culture solution to 2 mg / L. Add 6 mL of ammonium chloride (30 mg / L) and sodium nitrite (50 mg / L) daily. After several days, if a large amount of light yellow deposits form on the surface of the loofah sponge, it can be considered that the attachment was successful. Remove and wash away the culture solution and easily detached bacteria with water. The simulated wastewater is Class V water quality with high nitrogen content, with a TN content of approximately 9 mg / L, an NH3-N content of approximately 5 mg / L, and other trace elements added.

[0034] (4) Finally, a flexible carrier loofah sponge containing submerged plants and two compound bacteria is surrounded into a cylinder by a flexible carrier hemp net, and then bound into an ellipsoidal packing material (connected in series). According to the different light requirements, the flexible carrier with submerged plants is placed on the upper layer, and the flexible carrier with compound bacteria is placed on the lower layer, thus obtaining the bio-enhanced flexible carrier for high nitrogen-containing water bodies.

[0035] (5) 10 L of simulated wastewater was injected into a transparent plexiglass column with a diameter of 0.13 m and a height of 1 m. The simulated wastewater was of Class V or worse quality with high nitrogen content, containing approximately 9 mg / L of TN and approximately 5 mg / L of NH3-N, and other trace elements were added. The prepared bio-enhanced flexible carrier was then placed into the plexiglass column, and samples were taken for analysis.

[0036] The nitrogen removal effect of the bio-enhanced flexible carrier prepared in the above embodiments is as follows: Figure 2 As shown, the removal efficiency of each pollutant tends to stabilize after about 20 days, with the removal rate of TN reaching about 84% and the removal rate of ammonia nitrogen reaching about 93%.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a bioaugmentation flexible carrier, characterized by, Includes the following steps: S1: Immerse the bio-based material in a composite calcium cross-linked chitosan solution, react for a certain time, add sodium hydroxide solution to adjust the pH to 6.8-8.0 and let it stand for a period of time to allow the composite calcium cross-linked chitosan to form a cationic film on the surface of the bio-based material. After drying, rinse off the outer layer of unadhered chitosan with water, and dry again to obtain a flexible carrier. The composite calcium cross-linked chitosan solution is prepared by slowly adding chitosan to an acetic acid solution and stirring to dissolve it. After the added chitosan is completely dissolved, add calcium chloride and stir again until completely dissolved to obtain a composite calcium cross-linked chitosan solution. The acetic acid solution is a 1-2% dilute acetic acid solution, and the mass ratio of chitosan to calcium chloride is 3:1-8:

1. The composite calcium cross-linked chitosan solution contains 0.2-1.5% chitosan. S2: Plant submerged plants on the flexible carrier prepared in S1, and select specific bacterial species to attach to the flexible carrier according to the water quality characteristics. Finally, after binding, it is shaped into an ellipsoidal tandem structure, which is the bio-enhanced flexible carrier.

2. The production method according to claim 1, characterized by, In step S1, the bio-based material is loofah sponge or hemp net.

3. The preparation method according to claim 1, characterized in that, In step S1, the reaction time for immersing the bio-based material in the composite calcium cross-linked chitosan solution is 3-5 h; the concentration of the sodium hydroxide solution is 2 mol / L; the standing time is 15-60 min; and the drying temperature is 30-70℃.

4. The preparation method according to claim 1, characterized in that, In step S2, the submerged plant is *Hydrilla verticillata*, *Ceratophyllum demersum*, *Vallisneria natans*, *Potamogeton malaianus*, or *Potamogeton crispus*. The submerged plant is planted by wrapping the buds or seedling roots of the submerged plant in the holes of a flexible carrier, or by fixing the seeds of the submerged plant in a flexible carrier, so that the roots of the submerged plant can grow out through the holes.

5. The preparation method according to claim 1, characterized in that, In step S2, the bacterial strain is a conventional water treatment strain for denitrification and phosphorus removal; the strain is loaded by placing a flexible carrier into a compound bacterial culture medium composed of one or more strains and culturing it for 3-6 days. During this period, continuous aeration is maintained to control the DO concentration in the culture medium at 2-4 mg / L, and ammonia nitrogen and nitrate nitrogen are added daily. When a light yellow deposit forms on the surface of the flexible carrier, the strain loading is considered successful. Finally, the carrier is rinsed with water; the compound bacterial culture medium contains carbon, nitrogen, phosphorus, and essential trace elements.

6. A bio-enhanced flexible carrier prepared according to the preparation method described in claims 1-5.

7. A method for ecological restoration of slow-flowing water bodies, using the bio-enhanced flexible carrier described in claim 6 for ecological restoration of slow-flowing water bodies.

Images