Preparation method of high-efficiency bacteria-algae composite biofilm for mariculture circulating seawater

Abstract

The present application relates to the field of aquaculture circulating seawater purification, and particularly relates to a preparation method of an efficient bacteria-algae composite biofilm for aquaculture circulating seawater, comprising the following steps: (1) water preparation: adding aquaculture circulating water and adding nutrient salt in an aquaculture biochemical tank, and adjusting pH and permanganate index; (2) adding modified carrier filler: adding modified hydrophilic wavy arc surface material to a primary biochemical tank, and adding modified hydrophilic polyurethane sponge to a secondary biochemical tank; (3) biofilm formation: keeping seawater circulation in the primary biochemical tank, keeping seawater circulation and aeration in the secondary biochemical tank, and cultivating under illumination until biofilm formation is completed. The chemical oxidation carrier filler is used in the present application, the surface roughness is increased and the hydrophilic group is generated, the hydrophilicity is preliminarily improved, the graphene oxide is further used to improve the hydrophilicity, the microorganisms are beneficial to gather and adhere to the carrier filler to form a relatively firm biofilm, the biofilm formation time is greatly shortened, and the nitrogen content in the aquaculture circulating seawater can be stably and continuously degraded.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aquaculture circulating seawater purification technology, and particularly relates to a preparation method of a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater. BACKGROUND

[0002] In the circulating water aquaculture system, the cultivation and maturation of the biofilm of the biological filter is an important link for the effective operation of the whole system, and plays a key role in controlling the concentrations of organic matter, ammonia nitrogen and nitrite nitrogen in the whole system. The biofilm is generally formed by the attachment and growth of beneficial microorganisms such as ammonia-oxidizing bacteria, nitrite bacteria and nitrifying bacteria on the filler carrier. When the aquaculture circulating water flows through the biological filter, the pollutants are first filtered, intercepted and adsorbed, and then oxidized and decomposed by the biofilm on the surface of the biological carrier.

[0003] Currently, the commonly used carrier fillers include polypropylene sponge, polyethylene sponge, polyvinyl chloride sponge, polyurethane sponge, and PVC, PE, PP, etc. Due to the poor hydrophilicity of the above-mentioned sponges, the attachment and growth of microorganisms on the surface of the sponges are seriously affected, resulting in that the biofilm is not firm and easy to fall off, the biofilm formation time is long, and the degradation of ammonia nitrogen and nitrite nitrogen is unstable and the degradation efficiency is low. Therefore, the present application provides a preparation method of a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater. SUMMARY

[0004] (I) In view of the deficiencies of the prior art, the present application provides a preparation method of a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater, which overcomes the problem of poor hydrophilicity of the carrier filler in the prior art, greatly shortens the biofilm formation time, and stably and continuously degrades the nitrogen content in the aquaculture circulating seawater.

[0005] (II) To achieve the above-mentioned purposes, the present application is implemented by the following technical scheme: a preparation method of a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater, comprising the following steps,

[0006] (1) water preparation: adding aquaculture circulating water and adding nutrient salt in the aquaculture biochemical tank (including the first biochemical tank and the second biochemical tank), and adjusting the pH to 7.5-8.5 and the permanganate index to 10-40 mg / L, i.e. preparing the circulating seawater in the aquaculture biochemical tank, and then aerating and circulating for 1 day. The aquaculture biochemical tank can circulate water in the tank, has water inlet and outlet facilities, and the water exchange frequency is 2-10 times / day, and the shape is not limited; can be aerated to ensure that the dissolved oxygen in the water in the tank reaches 7.5 mg / L or more. The aquaculture circulating water includes nitrifying bacteria, EM bacteria and low-interest diatoms, and the total number of heterotrophic bacteria in the water is greater than 10,000 cfu / mL, and low-interest diatoms can be detected in the microscopic examination.

[0007] (2) Add modified carrier filler: add modified hydrophilic wave-shaped curved surface material to the primary biochemical tank of the breeding biochemical tank, so that it is immersed in circulating seawater and illuminated; add modified hydrophilic polyurethane sponge to the secondary biochemical tank of the breeding biochemical tank, so that it is suspended in circulating seawater for aeration and illumination.

[0008] (3) Biofilm formation: maintain seawater circulation in the primary biochemical tank and seawater circulation and aeration in the secondary biochemical tank, and give light on the water surface for cultivation until the biofilm formation is completed, thereby obtaining a high-efficiency bacteria-algae composite biofilm.

[0009] Preferably, in step (1), hydrochloric acid or sodium bicarbonate is used to adjust the pH, and glucose is used to adjust the permanganate index.

[0010] Preferably, in step (1), the nutrient salt is prepared according to the amount of breeding circulating water as follows: sodium chloride 15-20‰, potassium chloride 2-5‰, calcium chloride 300-400 mg / L, magnesium chloride 600-800 mg / L, potassium dihydrogen phosphate 5-20 mg / L, ferrous sulfate 5-20 mg / L, strontium chloride 1-2 mg / L, copper sulfate 0.01-0.5 mg / L, potassium silicate 0.1-2 mg / L, zinc sulfate 0.01-0.5 mg / L, sodium tetraborate 0.001-0.05 mg / L, sodium molybdate 0.001-0.05 mg / L, cobalt chloride 0.001-0.05 mg / L, potassium permanganate 0.001-0.05 mg / L, ammonium chloride 10-50 mg / L, and sodium nitrite 10-50 mg / L.

[0011] Preferably, in step (2), the modified hydrophilic polyurethane sponge accounts for 1 / 10-1 / 3 of the volume of the secondary biochemical tank.

[0012] Preferably, in step (2), the modified carrier filler includes modified hydrophilic wave-shaped curved surface material and modified hydrophilic polyurethane sponge, and the specific preparation process is as follows,

[0013] S1: Put the wave-shaped curved surface material and polyurethane sponge into an acidic potassium permanganate solution at 55℃ for 2h, then wash repeatedly with deionized water, and dry to obtain pretreated wave-shaped curved surface material and pretreated polyurethane sponge.

[0014] S2: Soak the pretreated wave-shaped curved surface material and pretreated polyurethane sponge in a graphene oxide dispersion solution for 1.5h, then dry to obtain modified hydrophilic wave-shaped curved surface material and modified hydrophilic polyurethane sponge.

[0015] Preferably, in step S1, the acidic potassium permanganate solution is composed of potassium permanganate, 98wt% sulfuric acid, and deionized water in a mass ratio of 1:1:12.

[0016] Preferably, in step S2, the concentration of the graphene oxide dispersion liquid is 5 mg / mL.

[0017] Preferably, in step (2), 10-80% of the modified hydrophilic polyurethane sponge is loaded into the corresponding non-closed polyurethane hollow suspended ball. It can freely move with the water flow in water, increasing the mobility of the modified hydrophilic polyurethane sponge in water.

[0018] Preferably, in step (3), the ammonia nitrogen and nitrite nitrogen concentrations in the water in the breeding biochemical tank are detected every day, and after 3-5 days of treatment, the ammonia nitrogen and nitrite nitrogen concentrations are less than 0.5 mg / L, and the biofilm is successfully formed.

[0019] Preferably, in step (3), the light intensity is 300-500 lx.

[0020] (Three) The present application provides a preparation method of a high-efficiency bacteria-algae composite biofilm for breeding circulating seawater, which has the following beneficial effects:

[0021] The present application first uses chemical oxidation wave-shaped curved surface material and polyurethane sponge to generate a large number of micro-cracks on the skeleton and surface thereof, increase the surface roughness, and generate hydrophilic groups such as C-O, C=O, and (C=O)-OH, thereby preliminarily improving the hydrophilicity of the wave-shaped curved surface material and the polyurethane sponge. Then, the hydrophilicity of the wave-shaped curved surface material and the polyurethane sponge is further improved by using graphene oxide, which is conducive to the aggregation and adhesion of microorganisms on the wave-shaped curved surface material and the polyurethane sponge to form a relatively firm biofilm. The graphene oxide is inserted into the micro-cracks, thereby improving the stability and greatly shortening the biofilm formation time, and stably and continuously degrading the nitrogen content in the breeding circulating seawater. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The present application provides a preparation flow chart of a high-efficiency bacteria-algae composite biofilm;

[0023] Figure 2 The present application provides a modified hydrophilic wave-shaped curved surface material and a modified hydrophilic polyurethane sponge diagram;

[0024] Figure 3 The present application provides a microscope diagram of a high-efficiency bacteria-algae composite biofilm;

[0025] Figure 4 The present application provides a biofilm formation schematic diagram of a high-efficiency bacteria-algae composite biofilm. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0027] Example 1

[0028] The preparation process of a modified carrier filler (modified hydrophilic wavy curved surface material and modified hydrophilic polyurethane sponge) is as follows:

[0029] S1: Soaking the wavy curved surface material and the polyurethane sponge in an acidic potassium permanganate solution at 55°C for 2 hours, removing them, and repeatedly washing them with deionized water. Drying them yields the pretreated wavy curved surface material and pretreated polyurethane sponge. The acidic potassium permanganate solution comprises potassium permanganate, 98 wt% sulfuric acid, and deionized water in a mass ratio of 1:1:12.

[0030] S2: Immersing the pretreated wavy arc-shaped surface material and the pretreated polyurethane sponge in a graphene oxide dispersion for 1.5 hours, taking them out and drying them to obtain a modified hydrophilic wavy arc-shaped surface material and a modified hydrophilic polyurethane sponge.

[0031] Example 2

[0032] A method for preparing a high-efficiency bacterial-algal composite biofilm for aquaculture circulating seawater comprises the following steps:

[0033] (1) Water preparation: Add aquaculture circulating water and nutrient salts to the aquaculture biochemical pond. At the same time, adjust the pH to 8.5 with hydrochloric acid or sodium bicarbonate and adjust the permanganate index to 40 mg / L with glucose, that is, prepare circulating seawater in the aquaculture biochemical pond, and then aerate and circulate for 1 day. The nutrient salts are prepared based on the amount of aquaculture circulating water, specifically as follows: sodium chloride 20‰, potassium chloride 5‰, calcium chloride 400 mg / L, magnesium chloride 800 mg / L, potassium dihydrogen phosphate 20 mg / L, ferrous sulfate 20 mg / L, strontium chloride 2 mg / L, copper sulfate 0.5 mg / L, potassium silicate 2 mg / L, zinc sulfate 0.5 mg / L, sodium tetraborate 0.05 mg / L, sodium molybdate 0.05 mg / L, cobalt chloride 0.05 mg / L, potassium permanganate 0.05 mg / L, ammonium chloride 50 mg / L, sodium nitrite 50 mg / L.

[0034] (2) Adding modified carrier fillers: Add modified hydrophilic wavy arc-shaped surface materials to the primary biochemical pool of the aquaculture biochemical pool, immerse them in circulating seawater and expose them to light; add modified hydrophilic polyurethane sponges to the secondary biochemical pool of the aquaculture biochemical pool, wherein 60% of the modified hydrophilic polyurethane sponges are loaded into corresponding non-closed polyurethane hollow suspended balls, and the modified hydrophilic polyurethane sponges occupy 1 / 3 of the volume of the aquaculture biochemical pool, so that they are all immersed and suspended in the circulating seawater for aeration and light.

[0035] (3) Hanging film: keep the seawater in the first biochemical pool circulating, the seawater in the second biochemical pool circulating and aeration, and give 500 lx light on the water surface to cultivate until the hanging film is completed, that is, the high-efficiency bacteria-algae composite biological membrane is obtained. The ammonia nitrogen and nitrite nitrogen concentrations in the water in the breeding biochemical pool are detected every day, and after 5 days of treatment, the ammonia nitrogen and nitrite nitrogen concentrations are both less than 0.5 mg / L, and the hanging film is successfully completed.

[0036] Verification: continue to add 50 mg / L of ammonium chloride to the water in the breeding biochemical pool according to the water volume, and measure the ammonia nitrogen and nitrite nitrogen every day. Within 3 days, the concentration is less than 0.5 mg / L, indicating that the hanging film has indeed been successfully completed.

[0037] In this embodiment, the modified carrier filler in Example 1 is used.

[0038] Example 3

[0039] A preparation method of a high-efficiency bacteria-algae composite biological membrane for breeding circulating seawater, comprising the following steps,

[0040] (1) Water preparation: add breeding circulating water and add nutrients to the breeding biochemical pool, and at the same time, adjust the pH to 7.5 with hydrochloric acid or sodium bicarbonate and adjust the permanganate index to 10 mg / L with glucose, that is, prepare the circulating seawater in the breeding biochemical pool, and then aerate and circulate for 1 day. The nutrients are prepared according to the amount of breeding circulating water as follows: sodium chloride 15 ‰, potassium chloride 2 ‰, calcium chloride 300 mg / L, magnesium chloride 600 mg / L, potassium dihydrogen phosphate 5 mg / L, ferrous sulfate 5 mg / L, strontium chloride 1 mg / L, copper sulfate 0.01 mg / L, potassium silicate 0.1 mg / L, zinc sulfate 0.01 mg / L, sodium tetraborate 0.001 mg / L, sodium molybdate 0.001 mg / L, cobalt chloride 0.001 mg / L, potassium permanganate 0.001 mg / L, ammonium chloride 10 mg / L, and sodium nitrite 10 mg / L.

[0041] (2) Add modified carrier filler: add modified hydrophilic wave-shaped curved surface material to the first biochemical pool of the breeding biochemical pool, so that it is immersed in the circulating seawater and illuminated; add modified hydrophilic polyurethane sponge to the second biochemical pool of the breeding biochemical pool, wherein 10% of the modified hydrophilic polyurethane sponge is packed into the corresponding non-closed polyurethane hollow suspended ball, and the modified hydrophilic polyurethane sponge accounts for 1 / 10 of the volume of the breeding biochemical pool, so that it is completely immersed and suspended in the circulating seawater for aeration and illumination.

[0042] (3) Hanging film: keep the seawater in the first biochemical pool circulating, the seawater in the second biochemical pool circulating and aeration, and give 300 lx light on the water surface to cultivate until the hanging film is completed, that is, the high-efficiency bacteria-algae composite biological membrane is obtained. The ammonia nitrogen and nitrite nitrogen concentrations in the water in the breeding biochemical pool are detected every day, and after 3 days of treatment, the ammonia nitrogen and nitrite nitrogen concentrations are both less than 0.5 mg / L, and the hanging film is successfully completed.

[0043] Verification: Continue to add 10 mg / L of ammonium chloride according to the water volume of the aquaculture biochemical pond, measure ammonia nitrogen and nitrite nitrogen every day, and within 3 days, the concentration will be less than 0.5 mg / L, indicating that the biofilm has been successfully formed.

[0044] In this embodiment, the modified carrier filler in Example 1 is used.

[0045] Comparative Example 1

[0046] A method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater is basically the same as Example 2, except that: a wavy arc surface material and a polyurethane sponge are used without hydrophilic modification.

[0047] During the biofilm formation process, after 14 days of treatment, the concentrations of ammonia nitrogen and nitrite nitrogen were both less than 0.5 mg / L, and biofilm formation was successful.

[0048] Comparative Example 2

[0049] A method for preparing an efficient bacterial-algal composite biofilm for aquaculture of circulating seawater is basically the same as Example 2, except that: the preparation process of the modified carrier filler is specifically to soak the wavy arc-shaped surface material and the polyurethane sponge in an acidic potassium permanganate solution at 55°C for 2 hours, take them out and repeatedly wash them with deionized water, and then dry them to obtain the modified hydrophilic wavy arc-shaped surface material and the modified hydrophilic polyurethane sponge.

[0050] During the biofilm formation process, after 10 days of treatment, the concentrations of ammonia nitrogen and nitrite nitrogen were both less than 0.5 mg / L, and biofilm formation was successful.

[0051] Comparative Example 3

[0052] A method for preparing an efficient bacterial-algal composite biofilm for aquaculture of circulating seawater is basically the same as Example 2, except that: the preparation process of the modified carrier filler is specifically to directly immerse the wavy arc-shaped surface material and the polyurethane sponge in a graphene oxide dispersion for 1.5 hours, take them out and dry them to obtain the modified hydrophilic wavy arc-shaped surface material and the modified hydrophilic polyurethane sponge.

[0053] During the biofilm formation process, after 10 days of treatment, the concentrations of ammonia nitrogen and nitrite nitrogen were both less than 0.5 mg / L, and biofilm formation was successful.

[0054] Detection

[0055] 1. Detect the concentrations of ammonia nitrogen and nitrite nitrogen in the aquaculture biochemical pond water every day. When the concentrations of both are less than 0.5 mg / L, it indicates that the biofilm formation is complete, and the number of days used can be calculated, as shown in the following table.

[0056] Table 1 Film forming days

[0057]

[0058] 2. The modified hydrophilic polyurethane sponges in Example 1 and Comparative Examples 1-3 were used as test objects, and the dynamic contact angles of the modified hydrophilic polyurethane sponges with distilled water were measured using a dynamic contact angle meter. The specific results are shown in the following table.

[0059] Table 2 Dynamic contact angle

[0060] Group Dynamic contact angle, ° Example 1 53.7 Comparative Example 1 75.6 Comparative Example 2 68.4 Comparative Example 3 65.9

[0061] The embodiments disclosed in the present invention are preferred embodiments, but are not limited to them. Ordinary technicians in this field can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. As long as they do not deviate from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A method for preparing a high-efficiency bacterial-algal composite biofilm for aquaculture circulating seawater, characterized in that: The following steps are included: (1) Water preparation: Add aquaculture circulating water and nutrient salts into the aquaculture biochemical pond, and adjust the pH to 7.5-8.5 and the permanganate index to 10-40 mg / L, that is, prepare circulating seawater in the aquaculture biochemical pond, and then aerate and circulate for 1 day; (2) Adding modified carrier fillers: Add modified hydrophilic wave arc surface materials to the first biochemical pool of the aquaculture biochemical pool, immerse it in the circulating seawater and expose it to light; add modified hydrophilic polyurethane sponge to the second biochemical pool of the aquaculture biochemical pool, suspend it in the circulating seawater for aeration and expose it to light; (3) Biofilm formation: Keep the seawater circulating in the primary biochemical pool and the seawater circulating and aerating in the secondary biochemical pool, and provide light cultivation on the water surface until the biofilm is formed, thus obtaining a high-efficiency bacterial-algal composite biofilm; In step (1), nutrient salts are prepared based on the amount of aquaculture circulating water, specifically as follows: sodium chloride 15-20‰, potassium chloride 2-5‰, calcium chloride 300-400mg / L, magnesium chloride 600-800mg / L, potassium dihydrogen phosphate 5-20mg / L, ferrous sulfate 5-20mg / L, strontium chloride 1-2mg / L, copper sulfate 0.01-0.5mg / L, potassium silicate 0.1-2mg / L, zinc sulfate 0.01-0.5mg / L, sodium tetraborate 0.001-0.05mg / L, sodium molybdate 0.001-0.05mg / L, cobalt chloride 0.001-0.05mg / L, potassium permanganate 0.001-0.05mg / L, ammonium chloride 10-50mg / L, sodium nitrite 10-50mg / L; In step (2), the modified carrier filler includes a modified hydrophilic wavy curved surface material and a modified hydrophilic polyurethane sponge. The specific preparation process is as follows: S1: Soaking the wavy curved surface material and the polyurethane sponge in an acidic potassium permanganate solution at 55° C. for 2 hours, taking them out and repeatedly washing them with deionized water, and drying them to obtain the pretreated wavy curved surface material and the pretreated polyurethane sponge; S2: Immersing the pretreated wavy arc-shaped surface material and the pretreated polyurethane sponge in a graphene oxide dispersion for 1.5 hours, taking them out and drying them to obtain a modified hydrophilic wavy arc-shaped surface material and a modified hydrophilic polyurethane sponge.

2. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step (1), hydrochloric acid or sodium bicarbonate is used to adjust the pH, and glucose is used to adjust the permanganate index.

3. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step (2), the modified hydrophilic polyurethane sponge occupies 1 / 10-1 / 3 of the volume of the secondary biochemical pool.

4. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step S1, the acidic potassium permanganate solution is composed of potassium permanganate, 98 wt % sulfuric acid and deionized water in a mass ratio of 1:1:

12.

5. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step S2, the concentration of the graphene oxide dispersion is 5 mg / mL.

6. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step (2), 10-80% of the modified hydrophilic polyurethane sponge is loaded into the corresponding non-closed polyurethane hollow suspension spheres.

7. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step (3), the concentrations of ammonia nitrogen and nitrite nitrogen in the water of the aquaculture biochemical pond are tested every day. After 3-5 days of treatment, the concentrations of ammonia nitrogen and nitrite nitrogen are both less than 0.5 mg / L, indicating successful biofilm formation.

8. The method for preparing a high-efficiency bacteria-algae composite biofilm for aquaculture circulating seawater according to claim 1, characterized in that: In step (3), the light intensity is 300-500 lx.

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