Method for quickly forming biological membrane for aquaculture water treatment system

Abstract

The invention provides a method for quickly forming a biological membrane for an aquaculture water treatment system. The method specifically comprises the following steps: step 1, selecting a biological membrane carrier; 2, preparing a certain amount of fulvic acid solution; 3, soaking the biofilm carrier in a fulvic acid solution for a period of time; step 4, when the step 3 is executed, aerating for a period of time, and then standing for anaerobic treatment for a period of time; 5, replacing a part of water after settling is completed; 6, after water is changed, fulvic acid is supplemented to reach the preset concentration; and 7, after standing for a period of time, forming a biological membrane on the surface of the biological membrane carrier. The enhanced bio-membrane reactor prepared by the method can remarkably shorten the membrane forming time and improve the water quality restoration effect, and has huge economic value and practical benefit.

Description

Technical Field

[0001] The invention relates to the field of aquaculture water treatment, and in particular to a method for rapid formation of a biofilm in an aquaculture water treatment system. Background Art

[0002] In the field of aquaculture, with the continuous development and expansion of the industry, a large amount of tail water is generated. Before discharging these tail waters into the external environment, it is crucial to effectively treat them. At present, biological methods, as a common and important treatment method, have significant advantages. First of all, biological methods have shown excellent efficiency in treating wastewater. By fully mobilizing the metabolic function of microorganisms, they can accurately and efficiently treat various pollutants in wastewater. For example, for pollutants such as organic matter and heavy metals, microorganisms can convert them into harmless or low-toxic substances, greatly reducing the pollution hazards caused by these pollutants to the environment. Not only that, biological methods for treating wastewater also fully reflect the characteristics of environmental friendliness. This treatment method not only removes pollutants, but also avoids the secondary pollution problems that may be caused by the use of chemical agents, and effectively protects the balance and stability of the ecological environment. More importantly, biological methods realize the recycling of resources, which is highly consistent with the strategic requirements of sustainable development. It enables useful substances in wastewater to be converted and utilized again, providing a feasible way for resource conservation and reuse. Among many biological treatment technologies, biofilm-based treatment technology has been widely used due to its unique advantages. Biofilm is a complex biological system composed of microorganisms and their secreted extracellular polymers. It has an extremely high surface area, which means that it can provide more adsorption and reaction sites, making the adsorption and degradation of pollutants more rapid and efficient. At the same time, the high biological activity of biofilms further enhances its ability to treat pollutants. Compared with the traditional activated sludge method, biofilm treatment technology has shown many advantages. In terms of treatment efficiency, it can remove pollutants in wastewater more quickly and thoroughly, ensuring that the treated water quality reaches higher standards. In terms of energy consumption, the energy input required for biofilm treatment technology is relatively low, which helps to reduce treatment costs and energy consumption. In addition, in terms of sludge production, the amount of sludge produced by biofilm treatment technology is significantly reduced, reducing the burden and cost of subsequent sludge treatment. In summary, biofilm-based treatment technology has shown broad application prospects and huge development potential in the field of wastewater treatment, which is of great significance for solving the problem of aquaculture tailwater treatment.

[0003] As an important method for treating organic wastewater, the principle of biofilm method is to achieve biodegradation of organic and inorganic substances in wastewater by microorganisms attached and grown on the surface of specific solids, that is, biofilm. In this process, the microorganisms contained in the biofilm play a key role. Through their own metabolic activities, they convert pollutants in wastewater into harmless or low-hazard substances. The rapid and stable formation of biofilm is a prerequisite for ensuring the successful start-up and full operation of the biofilm process. However, in actual application, problems such as long biofilm formation time, loose structure, and easy detachment have always plagued treatment efficiency and operating costs. Therefore, it is particularly important to study how to effectively promote biofilm formation. This is of great significance for significantly improving the effect of wastewater treatment, reducing treatment costs, and improving the stability and reliability of the treatment system. It not only helps to promote the wider application of biofilm method in the field of sewage treatment, but also provides strong technical support for solving the increasingly serious water pollution problem. Summary of the invention

[0004] The core purpose of the present invention is to provide an innovative and efficient method for rapid formation of biofilm in an aquaculture water treatment system, aiming to effectively and efficiently realize the rapid formation of biofilm on a carrier, thereby improving the overall effect and efficiency of aquaculture water treatment.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a method for rapid formation of biofilm in an aquaculture water treatment system, which specifically includes the following steps:

[0006] Step 1: Selecting a biofilm carrier;

[0007] Step 2, preparing a certain amount of fulvic acid solution;

[0008] Step 3: Completely immerse the selected biofilm carrier in the prepared fulvic acid solution for a period of time.

[0009] Step 4: When executing step 3, first perform aeration operation for a period of time, and then let it stand anaerobic for a period of time;

[0010] Step 5: Replace part of the water after sedimentation is complete; this step is to remove possible impurities and metabolites, optimize the treatment environment, and create purer and more favorable conditions for the further growth and development of the biofilm. When replacing water, it is necessary to control the amount and speed of water replacement to avoid excessive impact and damage to the established microbial community and biofilm structure.

[0011] Step 6: After changing the water, add fulvic acid to a predetermined concentration;

[0012] Step 7: After a period of time, a biofilm is formed on the surface of the biofilm carrier.

[0013] Preferably, the biofilm carrier adopts K5 biofilm reactor filler.

[0014] Preferably, the concentration of fulvic acid is 20 mg / L to 1500 mg / L.

[0015] Preferably, the concentration of fulvic acid is 500 mg / L to 1500 mg / L.

[0016] Preferably, in step 4, the aeration time is controlled to be 10 hours, and the anaerobic standing time is 2 hours.

[0017] The present invention also provides a water treatment method for aquaculture, which specifically comprises the following steps:

[0018] Step a, filtering the aquaculture water to be treated, and removing solid particles and impurities in the water through a filter screen or a filter medium;

[0019] Step b, precipitating the filtered aquaculture water;

[0020] Step c, placing the precipitated aquaculture water into a biofilm reactor, and using the above-mentioned method for rapid biofilm formation to form biofilm in the biofilm reactor;

[0021] Step d: After a period of reaction, the microorganisms on the biofilm decompose the substances in the aquaculture water to achieve water treatment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The method proposed in the present invention cleverly and innovatively uses fulvic acid to achieve efficient biofilm formation on a carrier. Fulvic acid, as a naturally occurring organic substance, has rich functional groups and complex molecular structures, and can interact with microorganisms and carrier surfaces in a variety of ways. Through glycolysis and tricarboxylic acid (TCA) cycle pathways, fulvic acid can significantly promote carbon source metabolism, which means that microorganisms can more effectively utilize carbon sources, produce more energy and metabolic intermediates, and provide a powerful driving force for their growth, reproduction, and biofilm formation. In this process, more available nicotinamide adenine dinucleotide (NADH) will be produced. These NADHs, as direct electron donors, play a key role in the heterotrophic denitrification process. They provide necessary electrons for denitrifying microorganisms and promote the conversion of nitrogen from nitrates or nitrites to nitrogen gas, thereby effectively reducing the content of nitrogen pollutants in water. In addition, fulvic acid can also stimulate the release of AHL (acyl homoserine lactone) in the aqueous phase and the biological phase. AHL is a quorum sensing signal molecule, and the increase in its release can improve the quorum sensing level between microorganisms, which enables better information exchange and synergy between microorganisms, thereby forming biofilms in a more orderly and efficient manner, and improving the overall performance and stability of the biofilm. Through the above series of mechanisms of action, the method of the present invention can not only significantly shorten the biofilm time and reduce the startup cycle of the water treatment system, but also greatly improve the efficiency and effect of water quality repair, which is extremely important for solving the water pollution problems faced in the aquaculture process and ensuring the health and sustainable development of the breeding environment. It has extremely important practical significance and application value.

[0024] The principle of fulvic acid accelerating biofilm formation is mainly in the following aspects:

[0025] Fulvic acid has good complexing and chelating ability, and can combine with metal ions in water to provide microorganisms with necessary trace elements and promote their growth and reproduction. For example, fulvic acid combines with iron ions to provide sufficient nutrition for microorganisms such as iron bacteria, enabling them to colonize and grow faster on the surface of the carrier, thereby accelerating the formation of biofilm.

[0026] Fulvic acid can improve the chemical environment of water, regulate pH and redox potential, and create suitable living conditions for microorganisms. For example, in an acidic environment, fulvic acid can buffer changes in pH, allowing microorganisms to grow and metabolize in a relatively stable environment, accelerating the formation of biofilms.

[0027] Fulvic acid can also enhance signal transmission and communication between microorganisms and promote the synergistic effect of microbial communities. For example, fulvic acid (FA) can promote carbon source metabolism through glycolysis and tricarboxylic acid (TCA) cycle pathways, produce more available nicotinamide adenine dinucleotide (NADH), and NADH acts as a direct electron donor to provide electrons for heterotrophic denitrification. Fulvic acid can also stimulate the release of AHL in the water phase and biological phase, improve quorum sensing, and thus enhance denitrification performance and biofilm formation. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly explain the embodiments of the present invention or the technical solutions in the prior art, the drawings necessary for the embodiments or the prior art descriptions are briefly introduced below. It is worth noting that the drawings described below are only part of the embodiments of the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work. Among them:

[0028] Figure 1 It is the state diagram of different fulvic acid concentrations in the carrier in the experimental example;

[0029] Figure 2 is the biofilm thickness of the reactor at different fulvic acid concentrations in the experimental case;

[0030] Figure 3 These are the water quality index data after treatment of reactor water generated at different fulvic acid concentrations in the experimental example. DETAILED DESCRIPTION In order to make the above-mentioned purposes, features and advantages of the present application clearer and easier to understand, the specific implementation methods of the present application will be described in detail below in conjunction with the accompanying drawings. It should be clear that the specific embodiments described herein are only used to explain the present application and are not limitations on the present application. In addition, it should be specifically noted that, for ease of description, only part of the structure related to the present application is shown in the accompanying drawings, not all. According to the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present application.

[0031] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0032] Embodiment 1

[0033] A method for rapidly forming a biofilm in an aquaculture water treatment system, comprising the following steps:

[0034] Step 1. Select the biofilm carrier and use the K5 reactor filler as the biofilm carrier; in this step, many factors need to be considered comprehensively, including but not limited to the material properties, physical structure and surface chemical properties of the carrier. The K5 reactor filler used is made of high molecular polyethylene, which has excellent chemical stability. It will not decompose, swell or deteriorate in the case of long-term contact with water and various chemicals, and can maintain the integrity of its structure and performance. High molecular polyethylene also has good corrosion resistance and can resist the erosion of common acids, alkalis, salts and other chemicals in sewage, extending the service life of the filler. In addition, the size of the K5 reactor filler is usually (Dx H) 25x 8mm, and its bulk density is 110kg / m 3 , specific surface area ≥600m 2 / m 3 . The larger specific surface area provides ample space for the attachment and growth of microorganisms, increases the contact opportunities between microorganisms and pollutants in sewage, and is beneficial to improving the efficiency of sewage treatment. It is worth noting that the surface of the K5 reactor filler carries a weak negative charge. This charge distribution is conducive to attracting positively charged microbial cells and promoting the attachment and growth of microorganisms on the filler surface. The surface of K5 usually contains functional groups such as hydroxyl and carboxyl. Hydroxyl can form hydrogen bonds with proteins and other substances on the surface of microbial cells, enhancing the binding force between microorganisms and fillers; carboxyl can react with metal ions in sewage to form complexes, which helps to remove certain heavy metal ions in sewage, and also provides certain nutrients for the growth of microorganisms.

[0035] Step 2: Prepare a certain amount of fulvic acid (FA) solution with a fulvic acid concentration of 500 mg / L; deionized water or purified water is preferred as the solvent to avoid interference of impurities on the properties of the solution. The preparation is carried out at room temperature (20-25°C) to ensure the stability of the chemical properties of fulvic acid. It is preferred to use a magnetic stirrer or mechanical stirrer for uniform stirring and ensure that fulvic acid is fully dissolved in the solvent. And the preparation container must be strictly cleaned and disinfected before use to prevent residual substances from affecting the concentration and properties of the solution. To ensure that the concentration and properties of the solution meet the requirements of subsequent processing.

[0036] Step 3, soaking the biofilm carrier in a fulvic acid solution for 12 hours;

[0037] Step 4: When executing step 3, aerate for 10 hours, and then let it settle under anaerobic conditions for 2 hours;

[0038] Step 5: After sedimentation is complete, replace 80% of the water;

[0039] Step 6: After changing the water, add fulvic acid to the set concentration;

[0040] Step 7: Place the solution for more than 7 days and control the solution temperature at 25-28°C to form a biofilm on the surface of the biofilm carrier. In this step, the formation of the biofilm needs to be closely monitored, including parameters such as its thickness, density, microbial community structure and activity. By evaluating these parameters, the progress and quality of biofilm formation can be judged, and necessary adjustment measures can be taken in time to ensure that the biofilm formation process meets expectations. Specifically, for the thickness of the biofilm, when it grows too slowly, it is necessary to check the nutrients, aeration volume and fulvic acid concentration. You can add trace metal element solution, increase the aerator power or increase the amount of fulvic acid supplement; when it is too fast or too thick, reduce the fulvic acid concentration, adjust the aeration strategy or increase the frequency and amount of water changes. When the biofilm density is low, evaluate the microbial inoculation amount, extend the aeration time, and ensure that the nutrient ratio is appropriate; when the density is high, reduce the inoculation amount, adjust the pH value or increase the anaerobic static sedimentation time. In terms of microbial community structure, the proportion of key functional microorganisms is low, and the conditions required for growth are supplemented; non-target microorganisms over-reproduce, check nutrients, use selective inhibitors or fine-tune the temperature. When the microbial activity is low, adjust the temperature, pH value, dissolved oxygen, supplement nutrients, and pre-treat the biofilm carrier; when the activity is too high, reduce the fulvic acid concentration, increase the anaerobic standing time, etc.

[0041] In step 2, the concentration of fulvic acid can be 20 mg / L to 1500 mg / L, preferably 500 mg / L to 1500 mg / L.

[0042] The fulvic acid is one of the humic substances with a size of 3500Da, which is mainly composed of elements such as carbon, hydrogen, oxygen and nitrogen, and is composed of lignite, sap and peat, as well as non-biological organic matter in soil and water ecosystems.

[0043] The solution in step 2 is an aqueous solution.

[0044] In step seven, the temperature of the solution is 25-28°C.

[0045] When in use, the obtained biofilm reactor is placed in the aquaculture water that needs to be treated, and the microorganisms in the biofilm reactor decompose organic and inorganic substances in the aquaculture water.

[0046] Embodiment 2

[0047] A water treatment method for aquaculture, specifically comprising the following steps:

[0048] Step a, filtering the aquaculture water to be treated, and removing solid particles and impurities in the water through a filter screen or a filter medium;

[0049] Step b, precipitating the filtered aquaculture water;

[0050] Step c, placing the precipitated aquaculture water into a biofilm reactor, and using the above-mentioned method for rapid biofilm formation to form biofilm in the biofilm reactor;

[0051] Step d: After a period of reaction, the microorganisms on the biofilm decompose the substances in the aquaculture water to achieve water treatment.

[0052] The specific steps of microbial decomposition of aquaculture water substances are as follows: First, there is the stage of microbial attachment and adaptation, in which the surface of the carrier adapts to water temperature, pH value, dissolved oxygen, etc., and secretes sticky substances for stable attachment. Then, in the early stage of organic matter decomposition, microorganisms secrete extracellular enzymes to decompose suspended macromolecular organic matter into small molecules, and ammonia oxidizing bacteria and other substances transform dissolved organic matter. Then, in the material transformation and removal stage, the biofilm matures, microorganisms use small molecule nutrients to grow and reproduce, denitrifying bacteria and other substances transform harmful substances, and microorganisms assimilate phosphorus. Finally, it reaches the stage of stable operation and dynamic balance, forming a complex ecosystem, and new and old microorganisms alternate to maintain the stability of the system. In practice, it still needs to be adjusted and optimized according to factors such as breeding density.

[0053] Experimental example

[0054] In this experiment, 10 SBBRs with a volume of 1 L were established to simulate the aquaculture water treatment system. The reactors included 10 groups (R0 to R9). The biofilm carrier material used in all reaction systems was high-density polyethylene, with a size of 10×25 mm, a specific surface area of ​​>500 m2 / m3, and a carrier filling volume of 40%. Fulvic acid (FA) (purchased from Maglin, purity 95%) was added at concentrations of 0, 20, 40, 50, 80, 100, 500, 1000, 1200 and 1500 mg / L, corresponding to R0, R1, R2, R3, R4, R5, R6, R7, R8 and R9 groups, respectively, see Figure 1 The operation cycle is 12h, including 10h of aeration and 2h of static anaerobic. After the sedimentation is completed, 80% of the water is replaced. After the water is replaced, FA is supplemented to the set concentration. The reactor is operated at 25-28℃ for 40 days. In order to better monitor the changes in the concentration of various pollutants during the experiment, the experimental water is the original wastewater from aquaculture (Channa argus pond, 300L, 10 tails). The indicators of the wastewater are as follows: COD is 100±3mg / L, TN is 107.9±0.7mg / L, TP is 27.1±0.3mg / L, NO3--N is 56.76±0.63mg / L, NO2--N is 0.27±0.15mg / L, NH4+-N is 34.53±0.1mg / L, and C / N is 1.8±0.03 (low C / N). The reactor was operated at 25-28°C for 40 days, the biofilm maturation time was shortened by 50-90%, and the water quality remediation efficiency was increased by 50%-80%, achieving good economic and ecological benefits.

[0055] from Figure 2 It can be seen that after 40 days of operation, the biofilm thickness of the other groups was 2.14, 3.33, .7, 6.67, 7.53, 7.62, 18.1, 27.4, and 31.55 times that of the control group, respectively. This shows that different concentrations of fulvic acid have a significant effect on the growth and thickness of the biofilm, greatly promoting the formation and growth of the biofilm.

[0056] from Figure 3 It can be seen that the TNRR are 12.51%, 12.50%, 12.33%, 14.60%, 2.41%, 12.02%, 27.62%, 57.90%, 55.70% and 63.48%, respectively, which are 0.999629491, 0.985550202, 1.167098924, 0.192663949, 0.961096701, 2.208595773, 4.62912189, 4.45350129 and 5.075213034 times that of the control group. Starting from 500 mg / L, the efficiency increases by 54.7%, 78.4%, 77.55% and 80.3%, respectively. It shows that when the concentration of fulvic acid is greater than 40 mg / L, it has a certain promoting effect on the removal of total nitrogen, especially when the concentration of fulvic acid is greater than 500 mg / L, it can significantly improve the removal rate of total nitrogen.

[0057] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for rapid formation of biofilm in an aquaculture water treatment system, characterized in that: The specific steps include: Step 1: Selecting a biofilm carrier; Step 2, preparing a certain amount of fulvic acid solution; Step 3, completely immersing the biofilm carrier in the fulvic acid solution for a certain period of time; Step 4: When executing step 3, first aerate for a period of time, and then let it settle for a period of time in an anaerobic environment; Step 5: Replace part of the water after sedimentation is completed; Step 6: After changing the water, add fulvic acid to a predetermined concentration; Step 7: After being placed for a period of time, a biofilm is formed on the surface of the biofilm carrier.

2. The method according to claim 1, characterized in that The biofilm carrier used is K5 biofilm reactor filler.

3. The method according to claim 1, characterized in that The fulvic acid is one of the humic substances with a size of <3500Da, mainly composed of carbon, hydrogen, oxygen and nitrogen, and is derived from lignite, tree sap and peat, as well as non-biological organic matter in soil and water ecosystems, which ensure the quality and characteristics of fulvic acid.

4. The method according to claim 1, characterized in that: The concentration of the fulvic acid is 20 mg / L to 1500 mg / L.

5. The method according to claim 1, characterized in that The concentration of the fulvic acid is 500 mg / L to 1500 mg / L.

6. The method according to claim 1, characterized in that In step 4, the aeration time is 10 hours and the static anaerobic time is 2 hours.

7. A water treatment method for aquaculture, comprising the following steps: Step a, filtering the aquaculture water to be treated, and removing solid particles and impurities in the water through a filter screen or a filter medium; Step b, precipitating the filtered aquaculture water; Step c, placing the precipitated aquaculture water into a biofilm reactor, and forming biofilm in the biofilm reactor using the method for rapid biofilm formation according to any one of claims 1 to 6; Step d: After a period of reaction, the microorganisms on the biofilm decompose the substances in the aquaculture water to achieve water treatment.

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