Biological coupling system of microalgae, TiO2, Ag and AgCl as well as construction method and application of biological coupling system

Abstract

The invention belongs to the technical field of microorganisms and catalytic degradation, and particularly relates to a biological coupling system of microalgae, TiO2, Ag and AgCl as well as a construction method and application of the biological coupling system. The invention provides a biological coupling system of microalgae, TiO2, Ag and AgCl, the biological coupling system comprises a microalgae carrier and nano particles, the nano particles are adhered to the surface of the microalgae carrier and / or wrapped in the microalgae carrier, and the nano particles are titanium dioxide with nano silver and silver chloride attached to the surface. The biological coupling system provided by the invention can quickly degrade phenolic compounds in wastewater, can completely degrade the phenolic compounds within 18 hours under the irradiation of natural light, and has a remarkable degradation effect on chlorine-containing phenolic compounds, and the degradation rate is close to 100%.

Description

Technical Field

[0001] The present invention belongs to the technical field of microorganisms and catalytic degradation, and particularly relates to a biological coupling system of microalgae with TiO 2 , Ag and AgCl, and a construction method and application thereof. Background Art

[0002] Phenolic compounds are derivatives from aromatic hydrocarbons and are usually used as active ingredients in herbicides, insecticides, drugs and dyes, as well as preservatives in wood processing in various industrial sectors. Phenolic compounds are aromatic organic compounds, many of which have acute toxicity, genotoxicity and endocrine disrupting effects. o-Cresol, as the most typical isomer among the three cresols, is the most common and more toxic. Discharged into natural water bodies without treatment, it will damage the ecological environment and endanger human life and health.

[0003] At present, there are various treatment methods for wastewater containing phenolic compounds. Among them, physical methods mainly include adsorption method, solution extraction method and liquid membrane method, but these methods cannot completely degrade phenolic compounds in wastewater; chemical methods usually include precipitation method, oxidation method, reduction method, neutralization method, electrolysis method and photocatalysis method, etc., but the treatment cost of this type of method is relatively high; biological treatment technologies mainly include activated sludge method, biological contact oxidation method and biological fluidized bed method, but their treatment effect is poor and the treatment time is relatively long. Moreover, the economy of these traditional wastewater treatment methods for phenolic compounds is poor, and secondary pollution is easily generated, which does not conform to the green development concept of wastewater treatment.

[0004] Although there is existing technology that uses the coupling of microalgae and nano-titanium dioxide to degrade phenol in wastewater, however, some wastewater generated in actual production often contains chlorinated phenolic compounds, such as o-chlorophenol, m-chlorophenol or p-chlorophenol. These chlorinated phenolic compounds have been regarded as priority pollutants by the World Health Organization and the US Environmental Protection Agency due to their characteristics of high toxicity, mutagenicity, carcinogenicity and persistence. Moreover, the physical and chemical properties of chlorophenols are very stable, and traditional biological, physical or chemical methods and the above-mentioned microalgae and nano-titanium dioxide coupling system capable of degrading phenol cannot degrade and eliminate them. Therefore, seeking low-carbon and economical phenol removal methods, especially for chlorinated phenolic compounds, has become an urgent and arduous task, which is of great significance for environmental protection and human health. Summary of the Invention

[0005] The purpose of the present invention is to provide a biological coupling system of microalgae with TiO 2 , Ag and AgCl, and a construction method and application thereof. This biological coupling system can rapidly degrade phenolic compounds in wastewater, and can completely degrade phenolic compounds under natural light irradiation within 20 h, and has a significant degradation effect on chlorinated phenolic compounds.

[0006] In view of this, in the first aspect of the present invention, a biological coupling system of microalgae with TiO 2 , Ag and AgCl is provided. The system includes a microalgae carrier and nanoparticles, and the nanoparticles are adhered to the surface of the microalgae carrier and / or wrapped inside the microalgae carrier. The nanoparticles include a titanium dioxide core and silver nanoparticles and silver chloride attached to the surface of the core.

[0007] The biological coupling system of microalgae with TiO 2 , Ag and AgCl provided by the present invention uses microalgae as a biological carrier, and then adheres nanoparticles to its surface and / or wraps the nanoparticles inside the microalgae carrier as it grows, thereby solving the problem of easy aggregation of nanoparticles. At the same time, the nanoparticles adhered to the surface of the microalgae will have a "protective" effect on the microalgae, enabling the microalgae to survive and grow in toxic wastewater, providing a carrier for the nanoparticles to attach to, and thus forming a positive cycle. In addition, the present invention uses titanium dioxide as the core and attaches silver nanoparticles and silver chloride to the surface of the core, enabling the coupling system to rapidly degrade phenolic compounds in wastewater, especially having excellent degradation effects on chlorinated phenolic compounds.

[0008] Combined with the first aspect, the particle size of the nanoparticles is 0.3 - 10 nm.

[0009] Combined with the first aspect, the microalgae includes at least one or several of 、 Tetradesmus obliquus, Chlorella vulgaris, Chlorella ellipsoidea or Chlorella protothecoides, preferably Chlorella ellipsoidea.

[0010] In the second aspect of the present invention, a method for constructing the above biological coupling system of microalgae with TiO 2 , Ag and AgCl is provided. The steps include:

[0011] S1. Take a microalgae culture solution, dissolve L-cysteine in the microalgae culture solution, add L-arginine, and stir evenly to obtain a microalgae solution.

[0012] S2. Add a buffer solution to the microalgae solution to adjust the pH value to 8.0 - 9.0, add dopamine hydrochloride and a titanium dioxide precursor bis(2-hydroxypropanoato)diammonium dihydroxytitanate(IV), stir for 15 - 60 min, and then add a silver nitrate solution and continue to stir for 15 - 60 min to obtain a biological coupling system of microalgae with TiO 2 , Ag and AgCl.

[0013] The biological coupling system of microalgae with TiO 2Method for constructing a biological coupling system of Ag and AgCl: Add L-cysteine and L-arginine with good biocompatibility to the microalgae culture solution and dissolve to obtain a microalgae solution; then add a buffer solution to the microalgae solution to make its pH value 8.0 - 9.0, add dopamine hydrochloride and titanium precursor diammonium bis(2-hydroxypropionate) dihydroxytitanium, so that the generated titanium dioxide is connected to the amino acids on the surface of the microalgae and adheres to the surface of the microalgae, and continue to add silver nitrate solution to form silver nanoparticles and silver chloride on the surface of the titanium dioxide.

[0014] The biological coupling system obtained by using the construction method provided by the present invention can form a benign cycle within itself. The nano-titanium dioxide particles with silver nanoparticles and silver chloride attached to the surface and the microalgae depend on each other, maximizing the overall effect of the biological coupling system. Among them, the presence of silver nanoparticles and silver chloride on the surface of the nanoparticles significantly improves the degradation rate of chlorinated phenolic compounds in wastewater by the biological coupling system, greatly expanding the application scope of the biological coupling system.

[0015] Preferably, the buffer solution used can be Tri-HCl buffer solution, phosphate buffer solution or other types of buffer solutions.

[0016] Combined with the second aspect, the reaction temperature is 20 - 30 °C. The reaction conditions of this construction method are at normal pressure, and the reaction temperature is close to room temperature, with mild reaction conditions, which is conducive to the normal growth and reproduction of microalgae.

[0017] Combined with the second aspect, the OD of the microalgae culture solution 680 is 0.1 - 2.0. For example, it can be 0.1 - 0.5, 0.5 - 1.0, or can also be 1.0 - 2.0.

[0018] Combined with the second aspect, 0.03 - 0.3 g of L-cysteine and 0.018 - 0.16 g of L-arginine are added to each liter of the microalgae culture solution, and 0.07 - 0.6 g of dopamine hydrochloride is added to each liter of the microalgae solution; the volume ratio of the buffer solution to the microalgae solution is 0.8 - 1.2:500, the volume ratio of the titanium dioxide precursor to the microalgae solution is 1:160 - 1500, and the volume ratio of the silver nitrate solution to the microalgae solution is 1:160 - 1500.

[0019] Preferably, the concentration of the silver nitrate solution is 0.1 mmol / L.

[0020] The third aspect of the present invention provides an application of a biological coupling system of microalgae and TiO 2 、Ag and AgCl or a biological coupling system constructed according to the above construction method in degrading wastewater containing phenolic compounds.

[0021] In combination with the third aspect, the phenolic compounds include o-cresol and chlorine-containing phenolic compounds.

[0022] Preferably, the chlorine-containing phenolic compounds can be o-chlorophenol, m-chlorophenol or p-chlorophenol.

[0023] The biological coupling system provided by the present invention not only solves the problem that microalgae are difficult to survive in high-concentration chemical reagents, but also combines the photocatalytic degradation effect of nanoparticles on organic pollutants and the decomposition effect of microalgae on pollutants, realizes the synergistic effect between biosynthesized nanoparticles and microalgae, thereby efficiently degrading phenolic compounds in wastewater, and also has a significant degradation effect on chlorine-containing phenolic compounds. Description of the Drawings

[0024] Figure 1 SEM spectrum of the biological coupling system of microalgae and TiO 2 , Ag and AgCl obtained in Example 1;

[0025] Figure 2 XPS spectrum of the biological coupling system of microalgae and TiO 2 , Ag and AgCl obtained in Example 1;

[0026] Figure 3 FESEM spectrum of the biological coupling system of microalgae and TiO 2 , Ag and AgCl obtained in Example 1;

[0027] Figure 4 Degradation effect diagrams of p-chlorophenol solutions for CK, Example 1, Comparative Examples 2-3;

[0028] Figure 5 Degradation effect diagrams of o-cresol solutions for Example 1, Comparative Examples 1-4. Detailed Embodiments

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] In the examples and comparative examples of the present invention, Chlorella ellipsoidea was purchased from the Freshwater Algae Culture Collection of the Chinese Academy of Sciences, and it is a dominant algal species for degrading p-chlorophenol obtained through screening together with Chlorella vulgaris, Chlorella pyrenoidosa and Chlorella ellipsoidea. Screening process: Four kinds of algae, namely Chlorella vulgaris, Chlorella ellipsoidea, Chlorella pyrenoidosa and Tetradesmus obliquus, were selected and first cultured in BG11 medium to obtain a microalgae concentrate. The microalgae concentrate and the p-chlorophenol solution were inoculated into 100 ml sterile Erlenmeyer flasks according to different volume ratios respectively, so that the OD of the microalgae680 = 1.0, and the concentration of the 4-chlorophenol solution to be degraded was made 100 mg / L. It was cultured in a light incubator with a light intensity of 4500 LX and a temperature of 30 °C, and the light condition was set as (light / dark cycle = 16 / 8 hours). The results showed that the degradation rates of Chlorella pyrenoidosa and Tetradesmus obliquus for 4-chlorophenol were slow, and the degradation rates of Chlorella vulgaris and Chlorella ellipsoidea for 4-chlorophenol were the fastest. Chlorella ellipsoidea was selected for the degradation experiment in this experiment.

[0031] The components of BG11 medium and the concentrations of each component are as follows: NaNO 3 1.5 g / L, K 2 HPO 4 0.004 g / L, MgSO 4 ·7H 2 O 0.075 g / L, CaCl 2 ·2H 2 O 0.036 g / L, citric acid 0.006 g / L, ammonium ferric citrate 0.006 g / L, 2Na-EDTA 0.001 g / L, Na 2 CO 3 0.02 g / L, H 3 BO 3 2.86 g / L, MnCl 2 ·4H 2 O 1.86 g / L, ZnSO 4 ·7H 2 O 0.22 g / L, Na 2 MoO 4 ·2H 2 O 0.39 g / L, CuSO 4 ·5H 2 O 0.08 g / L and Co(NO 3 ) 2 ·6H 2 O 0.05 g / L. The pH value was adjusted to 7.1 with 1 M NaOH solution or HCl solution.

[0032] The purity of the reagents used in the following examples and comparative examples of the present invention was all analytical pure.

[0033] Example 1

[0034] This example provides a biological coupling system of microalgae and TiO 2 , Ag and AgCl, and its construction method is as follows:

[0035] The activated algal solution was inoculated into a sterilized conical flask to OD 680= 1.0, a total of 100 mL, placed on a magnetic stirrer for stirring, and 0.01 g of L-cysteine was added. After stirring and dissolving, 0.0053 g of L-arginine was added. After continuous stirring and dissolving, 200 μL of Tris-HCl buffer solution (pH = 8.5) was added, the pH value was adjusted to 8.0 - 9.0, then 0.02 g of dopamine hydrochloride and 200 μL of 50 wt% diammonium bis(2-hydroxypropionate) titanate were added. After stirring for 15 min, 200 μL of 0.1 mM silver nitrate solution was added and stirred for another 15 min to obtain a biological coupling system of microalgae and TiO 2 , Ag and AgCl.

[0036] The microstructure of the particles in the obtained biological coupling system was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM), and the results are shown respectively as Figures 1 to 3 follows.

[0037] It can be seen from Figure 1 that the nanoparticles aggregated and adhered to the surface of the microalgae cells, indicating the successful synthesis of a biological coupling system of microalgae and TiO 2 , Ag and AgCl.

[0038] It can be observed from Figure 2 (a) that the XPS peaks of Ti 2p, Ag 3d and Cl 2p; in the high-resolution Ag 3d spectrum ( Figure 2 (b)), the characteristic peaks of Ag 3d 5 / 2 (367.54 eV) and Ag 3d 3 / 2 (373.40 eV) are related to metallic nano-Ag; the binding energy peaks of Ag 3d 5 / 2 (367.46 eV) and Ag 3d 3 / 2 (373.70 eV) correspond to Ag in silver chloride + . It can be observed from Figure 2 (c) that the two decomposed peaks in the Cl 2p spectrum are Cl 2p 3 / 2 (197.27 eV) and Cl 2p 1 / 2 (198.89 eV); the high-resolution Ti 2p ( Figure 2 (d)) shows the characteristic peaks of Ti 2p 1 / 2 (463.36 eV) and Ti 2p 3 / 2 (457.70 eV), indicating the existence of Ti 4+ valence state in titanium dioxide. Figure 2 It shows that the biological coupling system contains titanium dioxide and metallic nano-silver and silver chloride attached to the surface of titanium dioxide.

[0039] It can be seen from Figure 3 that in the obtained bio-coupling system, silver nanoparticles and silver chloride are uniformly dispersed and attached to the surface of titanium dioxide.

[0040] Example 2

[0041] This example provides a bio-coupling system of microalgae with TiO 2 , Ag and AgCl, and its construction method is as follows:

[0042] In a sterilized conical flask, add the activated algal solution to OD 680 = 2.0, a total of 100 mL, place it on a magnetic stirrer and stir, add 0.005 g L-cysteine, after stirring and dissolving, add 0.0020 g L-arginine, continue to stir and dissolve, then add 200 μL Tris-HCl buffer (pH = 8.5), adjust the pH value to 8.0 - 9.0, then add 0.01 g dopamine hydrochloride and 70 μL 50 wt% diammonium bis(2-hydroxypropionate) dihydroxotitanate, stir for 20 min, and then add 70 μL 0.1 mM silver nitrate solution and continue to stir for 25 min to obtain a bio-coupling system of microalgae with TiO 2 , Ag and AgCl.

[0043] Example 3

[0044] This example provides a bio-coupling system of microalgae with TiO 2 , Ag and AgCl, and its construction method is as follows:

[0045] In a sterilized conical flask, add the activated algal solution to OD 680 = 0.1, a total of 100 mL, place it on a magnetic stirrer and stir, add 0.03 g L-cysteine, after stirring and dissolving, add 0.016 g L-arginine, continue to stir and dissolve, then add 220 μL phosphate buffer (pH = 8.2), adjust the pH value to 8.0 - 9.0, then add 0.06 g dopamine hydrochloride and 600 μL 50 wt% diammonium bis(2-hydroxypropionate) dihydroxotitanate, stir for 55 min, and then add 600 μL 0.1 mM silver nitrate solution and continue to stir for 55 min to obtain a bio-coupling system of microalgae with TiO 2 , Ag and AgCl.

[0046] Comparative Example 1

[0047] This comparative example provides a bio-coupling system of microalgae with TiO 2 , and its construction method is as follows:

[0048] In a conical flask, add the activated algal solution to OD680 = 1.0, a total of 100 mL. Add 0.01 g of cysteine, stir to dissolve, then add 0.0053 g of arginine, continue to stir to dissolve, and then dropwise add 200 μL of 50 wt.% diammonium titanium bis(2-hydroxypropionate). After adding, stir for 15 min to obtain a biological coupling system of microalgae and TiO 2 and.

[0049] Comparative Example 2

[0050] This comparative example provides a pure microalgae biological system, in which the microalgae selected are Chlorella ellipsoidea.

[0051] Comparative Example 3

[0052] Heat the biological coupling system of microalgae and TiO 2 , Ag and AgCl obtained in Example 1 at 80 °C for 20 min to kill the microalgae in the system.

[0053] Comparative Example 4

[0054] Heat the biological coupling system of microalgae and TiO 2 obtained in Comparative Example 1 at 80 °C for 20 min to kill the microalgae in the system.

[0055] Test Example 1

[0056] Respectively, perform photocatalytic degradation tests on the biological systems obtained in Examples 1-3 and Comparative Examples 1-4 on the p-chlorophenol solution. At the same time, use a p-chlorophenol solution with a similar concentration as the blank control group, denoted as CK. Mix each biological system obtained in Examples 1-3 and Comparative Examples 1-4 with the p-chlorophenol solution and stir evenly to obtain a to-be-degraded solution system with a p-chlorophenol solution concentration of about 100 mg / L (the specific concentration of the p-chlorophenol solution is related to the addition amount of the biological system). Set the degradation temperature to 30 °C, the light intensity to 4500 LX, and the periodic light-dark ratio to 16:8. Use high-performance liquid chromatography to detect the p-chlorophenol concentration in the above blank control group and experimental group at different degradation times. Plot a curve with the degradation time as the abscissa and the detected p-chlorophenol solution concentration as the ordinate to obtain the trend diagram of the change in p-chlorophenol concentration over time during the photocatalytic degradation of each biological system. Among them, the photocatalytic degradation efficiency data of Examples 1-3 and Comparative Examples 1-4 are shown in Table 1; the concentration changes of p-chlorophenol during the photocatalytic degradation of the blank control group and the use of Examples 1 and Comparative Examples 2-3 on the p-chlorophenol solution with a concentration of about 100 mg / L are as Figure 4 shown.

[0057] Table 1 Degradation efficiency of the biological systems obtained in Examples 1-3 and Comparative Examples 1-4 on p-chlorophenol

[0058]

[0059] Combined with Table 1 and Figure 4 it can be seen that the biological system coupling only microalgae with titanium dioxide (Comparative Example 1) can hardly degrade p-chlorophenol, while the microalgae in the biological coupling system of microalgae with TiO 2 or microalgae with TiO 2 , Ag and AgCl are inactivated (corresponding to Comparative Example 4 and Comparative Example 3 respectively) or the individual microalgae (Comparative Example 2) have a low degradation efficiency for p-chlorophenol, and the degradation efficiency is not higher than 21%. However, for the biological coupling system of microalgae with TiO 2 provided by the present invention, Ag and AgCl, the degradation efficiency for p-chlorophenol can reach 22% when degrading for 33 h, up to 50% at most, and can achieve complete degradation at 66 h, and the lowest degradation efficiency is still higher than 30%. It shows that there is a synergistic effect between the microalgae in the biological coupling system of microalgae with TiO 2 provided by the present invention, Ag and AgCl and the titanium dioxide particles with silver nanoparticles and silver chloride attached to the surface. After coupling the two, the degradation efficiency for p-chlorophenol is greatly improved.

[0060] Test Example 2

[0061] The biological systems obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were respectively subjected to photocatalytic degradation tests on o-cresol solutions. Each biological system was mixed with the o-cresol solution and stirred evenly to obtain a to-be-degraded solution system with an o-cresol solution concentration of about 100 mg / L (the specific concentration of the o-cresol solution is related to the addition amount of the biological system). The degradation temperature was set at 30 °C, the light intensity was 4500 LX, and the periodic light-dark ratio was 16:8. The o-cresol solution was detected at different degradation times by high performance liquid chromatography, and the detected o-cresol concentration was denoted as C t , with the degradation time as the abscissa and the degradation efficiency (1 - C t / C 0 ) as the ordinate to plot a curve. Among them, the photocatalytic degradation efficiencies of Examples 1 to 3 and Comparative Examples 1 to 4 for o-cresol are shown in Table 2; the photocatalytic degradation efficiencies of Example 1 and Comparative Examples 1 to 4 for o-cresol are as Figure 5 shown.

[0062] Table 2 Degradation efficiencies of the biological systems obtained in Examples 1 to 3 and Comparative Examples 1 to 4 for o-cresol

[0063]

[0064]

[0065] Combined with Table 2 and Figure 5 it can be seen that for the microalgae with TiO 2The biodegradation efficiency of the biological coupling system of TiO₂, Ag and AgCl for o-cresol can reach up to 51% at the 12th hour, and o-cresol can be completely degraded within 18 hours at the fastest and within 28 hours at the slowest. However, after inactivating the microalgae in the coupling system (Comparative Examples 3-4) or using pure microalgae (Comparative Example 2), the degradation efficiency of o-cresol is greatly reduced, indicating that the microalgae provided in the present invention and TiO₂ 2 、Ag and AgCl biological coupling system can significantly improve the degradation efficiency of o-cresol. In addition, although the biological system in which microalgae are only coupled with titanium dioxide (Comparative Example 1) can basically completely degrade o-cresol at the 28th hour of degradation, its degradation rate is much lower than that of Example 1 of the present invention, and it can hardly degrade chlorinated phenolic compounds such as p-chlorophenol.

[0066] In summary, the biological coupling system of microalgae and TiO₂ 2 、Ag and AgCl provided by the present invention can not only rapidly degrade phenolic compounds, but also has an outstanding degradation effect on chlorinated phenolic compounds (100% complete degradation can be achieved within 18 hours at the fastest).

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A biological coupling system of microalgae, TiO2, Ag and AgCl, characterized in that: The invention comprises a microalgae carrier and nanoparticles. The nanoparticles are adhered to the surface of the microalgae carrier and / or wrapped inside the microalgae carrier. The nanoparticles comprise a titanium dioxide core body and nanosilver and silver chloride attached to the surface of the core body.

2. The biological coupling system of microalgae, TiO2, Ag and AgCl according to claim 1, characterized in that: The particle size of the nanoparticles is 0.3-10 nm.

3. The biological coupling system of microalgae, TiO2, Ag and AgCl according to any one of claims 1 to 2, characterized in that: The microalgae include at least one or more of Tetraselmis obliquus, Chlorella vulgaris, Chlorella ellipsoidea or Chlorella proteinaceous.

4. The method for constructing a biological coupling system of microalgae and TiO2, Ag and AgCl according to any one of claims 1 to 3, characterized in that the steps include: S1, taking a microalgae culture solution, dissolving L-cysteine ​​in the microalgae culture solution, adding L-arginine, and stirring and mixing to obtain a microalgae solution; S2. Add a buffer solution to the microalgae solution to adjust the pH value to 8.0-9.0, add dopamine hydrochloride and titanium dioxide precursor di(2-hydroxypropionic acid) diammonium dihydroxide, stir for 15-60 minutes, then add a silver nitrate solution and continue stirring for 15-60 minutes to obtain a bio-coupling system of microalgae, TiO2, Ag and AgCl.

5. The method for constructing a biological coupling system of microalgae and TiO2, Ag and AgCl according to claim 4, characterized in that: The reaction temperature is 20-30°C.

6. The method for constructing a biological coupling system of microalgae and TiO2, Ag and AgCl according to claim 4, characterized in that: The OD of the microalgae culture solution 680 It is 0.1~2.

0.

7. The method for constructing a biological coupling system of microalgae and TiO2, Ag and AgCl according to claim 4, characterized in that: 0.03-0.3 g L-cysteine ​​and 0.018-0.16 g L-arginine are added to each liter of the microalgae culture solution, and 0.07-0.6 g dopamine hydrochloride is added to each liter of the microalgae solution; the volume ratio of the buffer solution to the microalgae solution is 0.8-1.2:500, the volume ratio of the titanium dioxide precursor to the microalgae solution is 1:160-1500, and the volume ratio of the silver nitrate solution to the microalgae solution is 1:160-1500.

8. Use of the bio-coupling system of microalgae and TiO2, Ag and AgCl as claimed in any one of claims 1 to 3 or the bio-coupling system constructed according to the construction method of the bio-coupling system of microalgae and TiO2, Ag and AgCl as claimed in any one of claims 4 to 7 in degrading wastewater containing phenolic compounds.

9. The use according to claim 8, characterized in that The phenolic compounds include o-cresol and chlorine-containing phenolic compounds.

10. The use according to claim 9, characterized in that The chlorine-containing phenolic compounds include o-chlorophenol, m-chlorophenol and p-chlorophenol.

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