Alginate-embedded biochar-strain compound as well as preparation method and application thereof

Abstract

The invention discloses an alginate-embedded biochar-strain compound as well as a preparation method and application thereof. The compound is prepared by adopting alginate-embedded biochar and saccharomycetes Mo which is resistant to antibiotics and has an ammonia nitrogen removal effect; wherein the saccharomycetes Mo is preserved in the China Center for Type Culture Collection on May 13, 2024, the preservation address is Wuhan University, Wuhan, China, and the preservation number is CCTCC NO: M 2024909. According to the alginate-embedded biochar-strain compound disclosed by the invention, the survival rate and the ammonia nitrogen removal rate of microorganisms can be improved, the pH application range can be expanded, and the tolerance to tetracycline can be enhanced.

Description

Technical Field

[0001] The invention relates to a strain complex, and in particular to an alginate-embedded biochar-strain complex and a preparation method and application thereof. Background Art

[0002] At present, biological methods for removing ammonia nitrogen are mainly based on biological denitrification processes such as ammonia oxidation and nitrification / denitrification. However, nitrogen-containing gas substances such as N2 and N2O will be produced in these processes, which will cause nitrogen loss and even increase greenhouse gas (N2O) emissions.

[0003] Ammonia assimilation to remove ammonia nitrogen from wastewater is to convert ammonia nitrogen in wastewater into microbial substances, and the generated bacteria can also be converted into other protein products, thus avoiding the problem of nitrogen loss and greenhouse gas emissions. However, there are still few studies on the removal of ammonia nitrogen from aquaculture wastewater by ammonia assimilation, and most of them focus on the exploration of bacteria. The research on the use of fungi to remove ammonia nitrogen from aquaculture wastewater needs to be deepened. On the other hand, the microorganisms used in the microbial method may be affected by other coexisting pollutants, such as antibiotics, in the process of removing pollutants. In the process of aquaculture, in order to prevent or inhibit aquatic biological diseases, a large amount of antibiotics are put into the aquaculture system. 30% to 90% of antibiotics cannot be effectively metabolized by aquatic organisms, which leads to the presence of a large amount of antibiotics in the water. The presence of antibiotics may inhibit the activity of microorganisms and the removal effect of ammonia nitrogen. In addition, free microorganisms may face problems such as competition from indigenous microorganisms and low degradation efficiency in the process of treating ammonia nitrogen. How to improve the efficiency of microbial treatment is another difficult problem currently faced. Summary of the invention

[0004] The purpose of the present invention is to provide an alginate-embedded biochar-strain complex and a preparation method and application thereof, which solves the problems of free microorganisms facing competition from indigenous microorganisms and low removal efficiency during actual wastewater treatment, can improve the survival rate of microorganisms and ammonia nitrogen removal rate, and can expand the pH application range and enhance tolerance to tetracycline.

[0005] In order to achieve the above-mentioned purpose, the present invention provides an alginate-embedded biochar-strain complex, which is prepared by using alginate to embed biochar and a yeast (Naganishia diffluens) Mo that is resistant to antibiotics and has the effect of removing ammonia nitrogen; wherein the yeast Mo has been deposited in the China Center for Type Culture Collection on May 13, 2024, and the deposit address is Wuhan University, Wuhan, China, and the deposit number is CCTCCNO: M 2024909.

[0006] Preferably, the alginate is solidified by calcium ion cross-linking.

[0007] Preferably, the biochar is selected from straw biochar.

[0008] Another object of the present invention is to provide a method for preparing the alginate-encapsulated biochar-strain complex, which comprises: stirring a sodium alginate aqueous solution, biochar and a bacterial solution of the yeast Mo to obtain a composite solution; dripping the composite solution drop by drop into a calcium ion aqueous solution for cross-linking and curing to obtain an alginate-encapsulated biochar-strain complex.

[0009] Preferably, the biochar is ground and passed through a 60-mesh sieve, and then the obtained biochar is rinsed with deionized water until it is neutral and dried.

[0010] Preferably, the yeast Mo is inoculated in LB liquid medium and cultured, then centrifuged to collect the cells, washed with physiological saline, and then physiological saline is added to the cells to disperse them into OD 600 The bacterial solution is 1.0.

[0011] Preferably, the concentration of the sodium alginate aqueous solution is 2%; or / and, the calcium ion aqueous solution is a CaCl2 aqueous solution; the concentration of the CaCl2 aqueous solution is 4%; or / and, the dosage ratio of the sodium alginate aqueous solution, biochar and the yeast Mo liquid is 1L:5g; or / and, the dosage ratio of the sodium alginate aqueous solution and the yeast Mo liquid is 10:1.

[0012] Preferably, after the cross-linking and curing is completed, the composite is filtered out, rinsed with deionized water, and dried at 30°C.

[0013] Another object of the present invention is to provide the use of the alginate-embedded biochar-strain complex in the removal of ammonia nitrogen.

[0014] Preferably, the dosage of the alginate-embedded biochar-strain complex is 8 g / L; or / and, the alginate-embedded biochar-strain complex can be used in an environment of pH 5 to 9; or / and, the alginate-embedded biochar-strain complex can tolerate 20 mg / L tetracycline; or / and, the alginate-embedded biochar-strain complex can be regenerated and reused.

[0015] The alginate-embedded biochar-strain complex of the present invention and its preparation method and application solve the problems that free microorganisms may face competition from indigenous microorganisms and low removal efficiency during actual wastewater treatment, and have the following advantages:

[0016] The present invention selects a laboratory-preserved yeast strain that has antibiotic (tetracycline) tolerance and can remove ammonia nitrogen through ammonia assimilation as one of the main parts of the complex, and selects straw biochar-loaded strains. Biochar can serve as a nutrient source and shelter for the strain, thereby having a chance to improve the survival rate of the strain. Sodium alginate is selected to embed biochar and strains to prepare a complex to improve the recyclability of the complex. The present invention has a good ammonia nitrogen removal effect and a high recovery rate, and can be applied to ammonia nitrogen treatment of aquaculture wastewater.

[0017] The ammonia nitrogen removal mechanism of the strain Mo of the present invention is ammonia assimilation, and no nitrate nitrogen and nitrite nitrogen are produced during the ammonia nitrogen removal process, and there is no nitrogen loss of gaseous nitrogen. In addition, the whole genome data of the strain Mo shows that Mo is resistant to antibiotics such as tetracyclines, salicylates, oxazolidinones, nitroimidazoles and mupirocin. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Physical pictures of the alginate-embedded biochar-strain complex prepared in Example 1 of the present invention; (a) the complex before drying; (b) the complex after drying.

[0019] Figure 2 These are the experimental results of the ammonia nitrogen removal efficiency of the alginate embedding material in Experimental Example 1 of the present invention.

[0020] Figure 3 These are the experimental results of the dosage of the biochar-strain complex embedded with sodium alginate in Experimental Example 2 of the present invention.

[0021] Figure 4 This is the result of investigating the ammonia nitrogen removal performance of the biochar-bacteria complex embedded in sodium alginate in Experimental Example 3 of the present invention.

[0022] Figure 5 These are the results of the effect of different pH values ​​on the ammonia nitrogen removal effect of the biochar-strain complex embedded in sodium alginate in Experimental Example 4 of the present invention.

[0023] Figure 6 These are the results of the effects of different tetracycline concentrations on the ammonia nitrogen removal effect of the biochar-strain complex embedded in sodium alginate in Experimental Example 5 of the present invention.

[0024] Figure 7 These are the regeneration experimental results of the biochar-strain complex embedded with sodium alginate in Experimental Example 6 of the present invention.

[0025] Figure 8 This is the actual application result of the biochar-strain complex embedded with sodium alginate in wastewater in Experimental Example 7 of the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that if the specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased from the market.

[0028] The present invention is based on a strain of yeast Mo that is resistant to antibiotics and has the effect of removing ammonia nitrogen, which was previously preserved by the inventor. It was deposited in the China Center for Type Culture Collection on May 13, 2024. The preservation address is Wuhan University, Wuhan, China. The taxonomic name is Naganishia diffluens and the preservation number is CCTCC NO: M2024909. Through whole-genome functional gene analysis, it is known that the yeast Mo can remove ammonia nitrogen by ammonia assimilation in the presence of antibiotics (tetracycline). However, free microorganisms may face problems such as competition from indigenous microorganisms and low degradation efficiency in the actual wastewater treatment process. Therefore, the present invention uses microbial immobilization technology to immobilize the strain in order to improve the survival rate of the microorganisms and the ammonia nitrogen removal rate.

[0029] The present invention uses biochar (taking straw biochar as an example) to fix the strain. Compared with other carrier materials, biochar has the advantages of high carbon content, large cation exchange capacity, high porosity, strong stability and rich surface functional groups. Alginate has multiple advantages such as good biocompatibility, high stability, environmentally friendly degradability and high safety. Therefore, alginate is used to embed biochar and strains to prepare a composite, in order to improve the recovery rate and reuse rate of biochar and strains.

[0030] The following is a detailed description of an alginate-embedded biochar-strain complex provided by the present invention and its preparation method and application through embodiments and experimental examples.

[0031] Example 1

[0032] An alginate-embedded biochar-strain complex, the preparation method of which comprises:

[0033] The purchased straw biochar was ground and passed through a 60-mesh sieve. The obtained biochar was then rinsed with deionized water until neutral and dried for later use.

[0034] The strain Mo was inoculated into LB basic liquid medium, and the culture temperature was set to 25°C and the culture time was 18 hours. After the culture was completed, the culture medium was centrifuged to collect the bacteria, and washed three times with 0.85% saline. Then, the saline was added to the bacteria to disperse them into OD 600 The bacterial solution is 1.0 (1.17×10 7 CFU / mL). Among them, LB basic liquid culture medium: each liter of culture medium contains 25g LB broth.

[0035] Prepare a 2% (w / w) sodium alginate aqueous solution (heat to dissolve), and after the solution cools to room temperature, add 5g / L of biochar and 10% (v / v) bacterial solution, respectively, and continue to stir evenly. Finally, use a syringe to drip the composite solution drop by drop into a 4% (w / w) CaCl2 aqueous solution for cross-linking and curing. After cross-linking for 1 hour, filter out the composite, rinse three times with deionized water, and place in an oven at 30°C for drying to obtain the final sodium alginate-encapsulated biochar-bacterial complex, see Figure 1 .

[0036] Comparative Example 1

[0037] A sodium alginate-embedded biochar composite, the preparation method of which comprises:

[0038] The purchased straw biochar was ground and passed through a 60-mesh sieve. The obtained biochar was then rinsed with deionized water until neutral and dried for later use.

[0039] Prepare a 2% sodium alginate aqueous solution (heat to dissolve), and after the solution cools to room temperature, add 5g / L of biochar and continue to stir evenly. Finally, use a syringe to drip the composite solution drop by drop into a 4% CaCl2 aqueous solution for cross-linking and curing. After cross-linking for 1 hour, filter out the composite, rinse three times with deionized water, and place in an oven at 30°C for drying to obtain the final sodium alginate-encapsulated biochar composite.

[0040] Comparative Example 2

[0041] A sodium alginate-embedded bacterial strain complex, the preparation method of which comprises:

[0042] The strain Mo was inoculated into LB liquid medium, and the culture temperature was set to 25°C for 18 hours. After the culture was completed, the culture medium was centrifuged to collect the bacteria, and washed three times with 0.85% saline. Then, saline was added to the bacteria to disperse them into OD 600 The bacterial solution is 1.0 (1.17×10 7 CFU / mL).

[0043] Prepare a 2% sodium alginate aqueous solution (heat to dissolve), and after the solution cools to room temperature, add 10% (v / v) bacterial solution to it and continue stirring evenly. Finally, use a syringe to drip the composite solution drop by drop into a 4% CaCl2 aqueous solution for cross-linking and curing. After cross-linking for 1 hour, filter out the complex, rinse it three times with deionized water, and place it in a 30°C oven for drying, and then obtain a sodium alginate-embedded strain complex.

[0044] Experimental Example 1 Experiment on the removal efficiency of ammonia nitrogen by alginate embedding material

[0045] The removal efficiency of ammonia nitrogen by sodium alginate, biochar, the sodium alginate-embedded biochar composite prepared in Comparative Example 1, the sodium alginate-embedded strain prepared in Comparative Example 2, and the sodium alginate-embedded biochar-strain composite prepared in Example 1 was compared as follows:

[0046] Simulated aquaculture wastewater: each liter of solution contains 250.0 mg C6H 12 O6, 38.2mg NH4Cl, 9.0mg KH2PO4, 100.0mg MgSO4·7H2O, 60.0mg CaCl2 and 5.0mg tetracycline. 12 O6 and NH4Cl can be adjusted according to actual concentration needs.

[0047] 50 mL of simulated aquaculture wastewater was placed in a 100 mL conical flask, the tetracycline concentration was 5 mg / L, the temperature was set to 25 °C, the pH was set to 7, and the dosage of each material was 8 g / L. Then the experiment was carried out at a speed of 150 r / min for 24 hours. After the cultivation, the mass concentration of ammonia nitrogen in the water sample was measured for comparison.

[0048] The results are as follows Figure 2 As shown in the figure, the removal rates of ammonia nitrogen by sodium alginate, biochar and biochar embedded in sodium alginate were all less than 50% after 24 hours of treatment. However, the removal rates of ammonia nitrogen by the sodium alginate-embedded strain and the sodium alginate-embedded biochar-strain complex were 92.5% and 93.3%, respectively. In addition, compared with the sodium alginate-embedded strain without biochar, the addition of biochar increased the strength of the complex, and the addition of biochar can provide the strain with nutrients such as carbon and nitrogen, as well as rich attachment sites and living environment, which is conducive to the long-term preservation and transportation of the complex.

[0049] Experimental Example 2 Experiment on the dosage of biochar-bacterial complex embedded with sodium alginate

[0050] A 100 mL conical flask was filled with 50 mL of simulated aquaculture wastewater (same as Experimental Example 1), the tetracycline concentration was 5 mg / L, the temperature was set to 25 ° C, the pH was set to 7, and the dosage of the sodium alginate-embedded biochar-strain complex prepared in Example 1 was set to 2, 5, 8, 10, 15, and 20 g / L. Then, the experiment was carried out at a speed of 150 r / min for 24 h. After the cultivation was completed, samples were taken to determine the mass concentrations of ammonia nitrogen and total nitrogen in the water samples.

[0051] The experimental results of compound dosage are as follows Figure 3 When the compound dosage is 8g / L, the removal rate of ammonia nitrogen by the compound can reach 91.02%. The compound dosage above 8g / L will not significantly increase the removal rate of ammonia nitrogen.

[0052] Experimental Example 3 Study on the ammonia nitrogen removal performance of biochar-bacterial complex embedded in sodium alginate

[0053] In 250 mL of simulated aquaculture wastewater, the ammonia nitrogen concentration was set to 10 mg / L, the tetracycline concentration was 5 mg / L, the dosage of the sodium alginate-embedded biochar-strain complex prepared in Example 1 was 8 g / L, the experimental temperature was set to 25°C, the pH was set to 7, and the shaking speed was 150 r / min. Then, samples were taken and filtered at 0, 2, 4, 8, 12, and 24 hours to determine the mass concentrations of ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and total nitrogen.

[0054] The removal characteristics of the composite for ammonia nitrogen are shown in Figure 4 As shown. The removal of ammonia nitrogen by the composite showed a rapid downward trend in the first 8 hours, and reached a maximum ammonia nitrogen removal rate of 93.31% at 24 hours. The change trend of total nitrogen concentration was roughly the same as that of ammonia nitrogen. At 32 hours, the concentrations of ammonia nitrogen and total nitrogen rebounded slightly, which may be due to the increase in the concentrations of ammonia nitrogen and total nitrogen caused by the lysis of the bacteria after the death of the bacteria. There was no accumulation of nitrate nitrogen and nitrite nitrogen throughout the process, indicating that the composite would not cause other forms of nitrogen pollution.

[0055] Experimental Example 4 Effect of different pH on ammonia nitrogen removal effect of biochar-bacterial complex embedded in sodium alginate

[0056] Free strains: 50 mL of simulated aquaculture wastewater (same as Experimental Example 1) was placed in a 100 mL conical flask, the tetracycline concentration was 5 mg / L, the pH was set to 5, 6, 7, 8 and 9 respectively, the bacterial inoculation amount was 2%, the experimental temperature was 25°C, and the speed was 150 r / min for 12 hours (the free strain had the highest ammonia nitrogen removal rate at this time). After the culture was completed, samples were taken to determine the mass concentration of ammonia nitrogen in the water sample.

[0057] Composite: 50 mL of simulated aquaculture wastewater (same as in Experimental Example 1) was placed in a 100 mL conical flask, the tetracycline concentration was 5 mg / L, the pH was set to 5, 6, 7, 8, and 9, respectively, the dosage of the sodium alginate-embedded biochar-strain composite prepared in Example 1 was 8 g / L, the experimental temperature was 25°C, and the rotation speed was 150 r / min for 24 h. After the culture was completed, the mass concentration of ammonia nitrogen in the water sample was measured.

[0058] Comparison of the removal effects of free strains and complexes on ammonia nitrogen removal under different pH conditions. Figure 5 As shown in the figure. The optimal pH range for free strain Mo in the process of removing ammonia nitrogen is 6 to 8. Compared with the free strain, the tolerance range of the complex to pH is expanded. Even under the conditions of pH 5 and 9, the removal rate of ammonia nitrogen by the strain can still reach more than 80%, which increases the application potential of the complex in actual wastewater treatment.

[0059] Experimental Example 5 Effect of different tetracycline concentrations on ammonia nitrogen removal efficiency of alginate-embedded biochar-bacterial complex

[0060] Free strains: 50 mL of simulated aquaculture wastewater (same as Experimental Example 1) was placed in a 100 mL conical flask, the tetracycline concentration was set to 0, 2, 5, 8, 10, 15, 20 mg / L, the pH was set to 7, the bacterial inoculation amount was 2%, the experimental temperature was 25 ° C, and the speed was 150 r / min for 12 hours. After the culture was completed, the mass concentration of ammonia nitrogen in the water sample was measured.

[0061] Composite: 50 mL of simulated aquaculture wastewater (same as in Experimental Example 1) was placed in a 100 mL conical flask, the tetracycline concentrations were set to 0, 2, 5, 8, 10, 15, and 20 mg / L, the pH was set to 7, the dosage of the sodium alginate-embedded biochar-strain composite prepared in Example 1 was 8 g / L, the experimental temperature was 25°C, and the rotation speed was 150 r / min for 24 h. After the culture was completed, samples were taken to determine the mass concentration of ammonia nitrogen in the water sample.

[0062] The removal effects of free strains and complexes on ammonia nitrogen removal under different tetracycline concentrations were compared. Figure 6 As shown. When the tetracycline concentration is below 5 mg / L, there is no significant change in the removal rate of ammonia nitrogen by the complex and free strains. When the tetracycline concentration increases from 5 mg / L to 20 mg / L, the removal rate of ammonia nitrogen by the complex decreases slightly. However, when the tetracycline concentration is 20 mg / L, the removal rate of ammonia nitrogen by the free strain is 72.4%, while the removal rate of ammonia nitrogen by the complex can still reach 84.3%. Therefore, it can be seen that compared with the free strain, the complex has a stronger tolerance to tetracycline concentration.

[0063] Experimental Example 6 Regeneration experiment of biochar-bacterial strain complex embedded in sodium alginate

[0064] 50 mL of simulated aquaculture wastewater (same as Experimental Example 1) was placed in a 100 mL conical flask, the tetracycline concentration was 5 mg / L, the temperature was set to 25 ° C, the pH was set to 7, and the dosage of the sodium alginate-embedded biochar-strain complex prepared in Example 1 was set to 8 g / L, and then the experiment was carried out at a speed of 150 r / min for 24 hours. After the culture was completed, the mass concentration of ammonia nitrogen in the water sample was measured. The used complex was then washed three times with deionized water to remove the bacteria and ammonia nitrogen attached to the surface, and then dried for regeneration experiments, and the number of regenerations was set to 5 times.

[0065] The results of the regeneration experiment are as follows Figure 7 The results show that the composite can be regenerated, and after 5 regenerations, the removal rate of ammonia nitrogen by the composite can still reach 92.37%. The composite improves the utilization rate of biochar and strain Mo.

[0066] Experimental Example 7 Practical application of sodium alginate-encapsulated biochar-bacterial strain complex in wastewater

[0067] Actual aquaculture water: Samples were collected from a carp breeding site in Guangdong Province. The initial concentrations of ammonia nitrogen, total nitrogen, nitrate nitrogen and nitrite nitrogen in the samples were 2.07, 3.68, 0.99 and 0.14 mg / L, respectively.

[0068] Actual ammonia nitrogen removal from aquaculture wastewater: 50 mL of aquaculture wastewater was placed in a 100 mL conical flask, and the dosage of the sodium alginate-embedded biochar-bacteria complex prepared in Example 1 was set to 8 g / L, and then the experiment was carried out at a speed of 150 r / min for 24 hours. After the cultivation was completed, samples were taken to determine the mass concentrations of ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and total nitrogen in the water sample.

[0069] The experimental results are as follows Figure 8 As shown, the composite has an effective removal rate for ammonia nitrogen in actual wastewater (2.07 mg / L to 0.11 mg / L), and has a certain removal capacity for nitrate nitrogen and nitrite nitrogen.

[0070] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. An alginate-embedded biochar-bacterial strain complex, characterized in that: The composite is prepared by using alginate to embed biochar and yeast (Naganishia diffluens) Mo which is resistant to antibiotics and has the effect of removing ammonia nitrogen; wherein the yeast Mo has been deposited in the China Center for Type Culture Collection on May 13, 2024, with the deposit address being Wuhan University, Wuhan, China, and the deposit number being CCTCC NO: M 2024909.

2. The alginate-embedded biochar-bacterial strain complex according to claim 1, characterized in that: The alginate is solidified by calcium ion cross-linking.

3. The alginate-embedded biochar-bacterial strain complex according to claim 1, characterized in that: The biochar is selected from straw biochar.

4. The method for preparing the alginate-embedded biochar-bacterial strain complex according to any one of claims 1 to 3, characterized in that: The preparation method comprises: The sodium alginate aqueous solution, biochar and the yeast Mo liquid are stirred uniformly to obtain a composite solution; The composite solution is dripped dropwise into a calcium ion aqueous solution for cross-linking and solidification to obtain an alginate-embedded biochar-strain composite.

5. The preparation method according to claim 4, characterized in that: The biochar was ground and passed through a 60-mesh sieve, and then the obtained biochar was rinsed with deionized water until it was neutral and dried.

6. The preparation method according to claim 4, characterized in that: The yeast Mo was inoculated in LB liquid medium and cultured, then centrifuged to collect the cells, washed with physiological saline, and then physiological saline was added to the cells to disperse them into OD 600 The bacterial solution is 1.

0.

7. The preparation method according to claim 4 or 6, characterized in that: The concentration of the sodium alginate aqueous solution is 2%; Or / and, the calcium ion aqueous solution is a CaCl2 aqueous solution; the concentration of the CaCl2 aqueous solution is 4%; Or / and, the dosage ratio of the sodium alginate aqueous solution to the biochar is 1L:5g; Or / and, the dosage ratio of the sodium alginate aqueous solution to the yeast Mo liquid is 10:

1.

8. The preparation method according to claim 4, characterized in that: After the cross-linking and curing is completed, the composite is filtered out, rinsed with deionized water, and dried at 30°C.

9. Use of the alginate-embedded biochar-strain complex as described in any one of claims 1 to 3 in the removal of ammonia nitrogen.

10. The use according to claim 9, characterized in that: The dosage of the alginate-embedded biochar-bacterial strain complex is 8 g / L; Or / and, the alginate-embedded biochar-bacterial strain complex can be used in an environment with a pH of 5 to 9; Or / and, the alginate-embedded biochar-bacterial strain complex can tolerate 20 mg / L tetracycline; Or / and, the alginate-embedded biochar-strain complex can be regenerated and reused.

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