Method for removing pentachlorophenol in water by using modified charcoal-based immobilized microbial agent
By modifying the biochar-based immobilized bacterial agent to load PCP-degrading bacteria and combining it with sodium pyruvate as a carbon source, the problems of low efficiency and high cost of PCP removal in water in the existing technology were solved, and a high-efficiency, low-cost, and environmentally friendly PCP removal effect was achieved.
Patent Information
- Application Number
- CN202510793660.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-19
AI Technical Summary
When existing technologies are used to remove pentachlorophenol (PCP) from water, physical adsorption fails to achieve degradation, chemical oxidation is costly and easily produces toxic intermediates, and biological degradation is greatly affected by environmental conditions, making it difficult to effectively remove PCP from water.
A modified biochar-based immobilized bacterial agent was used, and modified biochar was used as a carrier to load PCP-degrading bacteria. PCP-degrading bacteria were obtained by acclimating activated sludge and immobilized on the modified biochar. Sodium pyruvate was used as a carbon source for degradation to form a modified biochar-based immobilized bacterial agent.
Efficient and low-cost PCP removal was achieved. The modified biochar provided a good microenvironment to protect the activity of degradation bacteria, and sodium pyruvate provided additional energy to improve the removal rate. It has the advantages of simple process, easy operation, and green environmental protection.
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Figure CN120664704A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of environmental bioremediation, and particularly relates to a method for removing pentachlorophenol in water by utilizing a modified biochar-based immobilized bacterial agent. Background Art
[0002] Pentachlorophenol (PCP) was once widely used as a snail-disinfecting pesticide in Chinese waters. Its stable chemical properties, while ensuring its high insecticide efficacy, also make it difficult to degrade naturally in the environment. To this day, PCP can still be detected in major rivers and lakes across my country. Reports indicate that PCP levels are highest in the Yangtze River basin, ranging from undetectable to 0.59 μg / L. PCP contamination in the Yangtze River basin stems both from PCP residues from long-term pesticide application in the basin provinces and from industrial wastewater discharge from PCP-using industries such as chemical production plants along the Yangtze River. With the exception of Hongze Lake, where no reports have been found, PCP residues have been detected in Poyang Lake, Dongting Lake, and Taihu Lake. Average PCP levels in these three lakes reach 3.76 μg / L. PCP levels in Dongting Lake are significantly higher than in other Chinese rivers and lakes, ranging from 0.005 to 103.7 μg / L. Therefore, how to deal with residual PCP in the water environment has gradually attracted the attention of researchers.
[0003] Currently, methods for removing PCP from water generally include physical adsorption, chemical oxidation, and biodegradation. Physical adsorption generally involves using an adsorbent to enrich pentachlorophenol in water, transferring pentachlorophenol from water to the adsorbent, without degrading and removing pentachlorophenol. Although chemical oxidation is efficient and fast, it is too expensive, residual oxidants require secondary treatment, and are prone to produce toxic intermediates such as polychlorobenzoquinone. Biodegradation has a low cost, can avoid secondary pollution, and reduces its harm to the environment, and has the advantage of being green and environmentally friendly. However, biodegradation is greatly affected by environmental conditions such as temperature and pH, and unsuitable environmental factors can reduce the activity of degrading bacteria. Therefore, finding a method for removing PCP from water using modified biochar-based immobilized bacterial agents with good treatment effects is of great practical significance for achieving effective removal of PCP from water bodies. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for removing pentachlorophenol in water by using a modified biochar-based immobilized bacterial agent, which has simple process, simple operation, low treatment cost and good removal rate.
[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions.
[0006] A method for removing pentachlorophenol in water using a modified biochar-based immobilized bacterial agent. The method comprises degrading pentachlorophenol-containing water using the modified biochar-based immobilized bacterial agent. The modified biochar-based immobilized bacterial agent uses modified biochar as a carrier, and PCP-degrading bacteria are loaded on the modified biochar. The PCP-degrading bacteria are obtained by acclimating activated sludge as a raw material and pentachlorophenol as a carbon source.
[0007] The above method is further improved, and the screening method for PCP-degrading bacteria comprises the following steps: acclimating the activated sludge in a pentachlorophenol-containing culture medium with a pentachlorophenol concentration of 5 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, and obtaining PCP-degrading bacteria through separation and purification; each cycle in the acclimation process is 14 days, the acclimation temperature is 30°C to 35°C, the pentachlorophenol-containing culture medium further comprises an inorganic salt culture medium, and the activated sludge is activated sludge from a municipal sewage treatment plant.
[0008] The above method is further improved, and the preparation method of the modified biochar-based immobilized bacterial agent comprises the following steps: (1) Activating and culturing PCP-degrading bacteria to obtain a bacterial suspension; (2) The bacterial suspension obtained in step (1) is mixed with the modified biochar and cultured to obtain a modified biochar-based immobilized bacterial agent.
[0009] The above method is further improved in that in step (2), the mass volume ratio of the modified biochar to the bacterial suspension is 0.2 g: 10 mL to 60 mL, and the OD600 of the bacterial suspension is 0.45 to 0.55.
[0010] The above method is further improved, in step (1), the temperature during the activation culture process is controlled at 30°C to 35°C, and the activation culture time is 72h to 96h; In step (2), the temperature during the culture process is controlled at 30°C to 35°C, and the culture time is 24h to 36h.
[0011] The above method is further improved, in step (2), the preparation method of the modified biochar comprises the following steps: (2.1) Pyrolyzing biomass materials to obtain biochar; (2.2) mixing the biochar obtained in step (2.1) and the potassium permanganate solution, and drying to obtain a mixture; (2.3) Pyrolyzing the mixture obtained in step (2.2) to obtain modified biochar.
[0012] The above method is further improved, in step (2.1), the biomass material is rice straw, the pyrolysis is carried out under an inert atmosphere or nitrogen, the heating rate during the pyrolysis process is 10°C / min, the pyrolysis temperature is 600°C, and the pyrolysis time is 4.5 hours; In step (2.2), the mass volume ratio of the biochar to the potassium permanganate solution is 2 g:100 mL, the concentration of the potassium permanganate solution is 0.025 M, and the mixing is performed under stirring for 2 h. In step (2.3), the pyrolysis is carried out under an inert atmosphere or nitrogen, the heating rate during the pyrolysis process is 10°C / min, the pyrolysis temperature is 600°C, and the pyrolysis time is 4.5 hours.
[0013] The above method is further improved, wherein the degradation treatment is specifically as follows: mixing the modified biochar-based immobilized bacterial agent with water containing pentachlorophenol, adding sodium pyruvate, and performing a degradation reaction to achieve degradation of pentachlorophenol in the water.
[0014] The above method is further improved in that the volume ratio of the modified biochar-based immobilized bacterial agent to the pentachlorophenol-containing water is 1:9, and the amount of sodium pyruvate added is 300mg-320mg per liter of pentachlorophenol-containing water.
[0015] The above method is further improved, wherein the initial concentration of pentachlorophenol in the pentachlorophenol-containing water is 5 mg / L to 120 mg / L, the initial pH value of the pentachlorophenol-containing water is 3 to 7, the pentachlorophenol-containing water also contains divalent cadmium, the concentration of divalent cadmium in the pentachlorophenol-containing water is ≤15 mg / L, the temperature of the degradation reaction is 30° C. to 35° C., and the time of the degradation reaction is ≥14 days.
[0016] Compared with the prior art, the advantages of the present invention are: In view of the shortcomings of existing PCP treatment technology in water, the present invention creatively proposes a method for removing pentachlorophenol in water using a modified biochar-based immobilized bacterial agent, and degrading PCP in water using a modified biochar-based immobilized bacterial agent, wherein the modified biochar-based immobilized bacterial agent includes a modified biochar carrier and loaded PCP-degrading bacteria. The method of the present invention, on the one hand, the PCP degrading bacteria used have good tolerance and biological activity, can degrade PCP into low-toxic or non-toxic metabolites, which is conducive to the removal of PCP; on the other hand, the modified biochar has a large specific surface area and strong adsorption capacity, which can promote PCP to migrate to the modified biochar. When the PCP degrading bacteria are fixed on the modified biochar, the PCP degrading bacteria can not only use PCP and biochar as carbon sources for value-added, but also make the PCP degrading bacteria gather at a high density in the modified biochar to maintain activity, thereby increasing the biomass and metabolic activity of the degrading bacteria. The modified biochar can also provide a sheltered microenvironment for the PCP degrading bacteria RB1, protecting it from the impact of external environmental factors, and maintaining the biological activity and tolerance of the PCP degrading bacteria, thereby increasing the concentration of microbial cells and the ability to resist environmental impact, and ultimately achieving good removal of pentachlorophenol. In addition, the method of the present invention, by adding sodium pyruvate, can provide additional energy for the PCP degrading bacteria, promote its further value-added and increase its metabolic activity, thereby improving the removal rate of PCP. The method of the present invention has the advantages of simple process, easy operation, low treatment cost, good removal rate, etc., has high practical value and good application prospect, and is a novel, green and environmentally friendly method for removing pentachlorophenol in water. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a phylogenetic tree diagram of the PCP-degrading bacteria RB1 in Example 1 of the present invention.
[0018] Figure 2 This is a scanning electron microscope image of the modified biochar-based immobilized bacterial agent in Example 1 of the present invention.
[0019] Figure 3 This is a diagram showing the removal effect of different concentrations of pentachlorophenol by the modified biochar-based immobilized bacterial agent and PCP-degrading bacteria in Example 1 of the present invention.
[0020] Figure 4 This is a diagram showing the removal effect of pentachlorophenol by different modified biochar-based immobilized bacterial agents in Example 2 of the present invention.
[0021] Figure 5 This is a diagram showing the removal effect of pentachlorophenol by PCP-degrading bacteria under different treatment conditions in Example 2 of the present invention.
[0022] Figure 6 This is a diagram showing the removal effect of pentachlorophenol by the modified biochar-based immobilized bacterial agent and PCP-degrading bacteria at different pH values in Example 3 of the present invention.
[0023] Figure 7 This is a diagram showing the removal effect of pentachlorophenol by the modified biochar-based immobilized bacterial agent and PCP-degrading bacteria in Example 4 of the present invention under the coexistence conditions of different concentrations of Cd(II). DETAILED DESCRIPTION
[0024] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby. The materials and instruments used in the following examples are all commercially available.
[0025] Example 1 A method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent of the present invention, specifically using the modified biochar-based immobilized bacterial agent to degrade water containing pentachlorophenol at different concentrations, comprising the following steps: According to the volume ratio of modified biochar-based immobilized bacterial agent to inorganic salt culture medium containing pentachlorophenol of 1:9, the modified biochar-based immobilized bacterial agent (A2) was added to 6 portions of inorganic salt culture medium containing pentachlorophenol, respectively. The concentrations of pentachlorophenol in the inorganic salt culture medium containing pentachlorophenol were 5 mg / L, 10 mg / L, 15 mg / L, 30 mg / L, 60 mg / L, and 120 mg / L, respectively. The initial pH value of the inorganic salt culture medium containing pentachlorophenol was 6. Sodium pyruvate was then added, and the amount of sodium pyruvate added was 300 mg per liter of inorganic salt culture medium containing pentachlorophenol. The degradation reaction was carried out at a rotation speed of 150 r / min and a temperature of 30°C for 14 days to complete the degradation of pentachlorophenol in water.
[0026] Control group 1: The modified biochar-based immobilized bacterial agent was replaced with a free bacterial agent, i.e., PCP-degrading bacteria, and sodium pyruvate was not added. Other conditions were the same.
[0027] Control group 2: The modified biochar-based immobilized bacterial agent was replaced with a free bacterial agent, i.e., PCP-degrading bacteria, and other conditions were the same.
[0028] After the cultivation is completed, samples are extracted and the PCP content is determined by high performance liquid chromatography (HPLC), and the removal rate of PCP by different bacterial agents is calculated. The results are as follows: Figure 3 shown.
[0029] In this embodiment, a modified biochar-based immobilized bacterial agent is used with the modified biochar as a carrier, and PCP-degrading bacteria are loaded on the modified biochar; wherein the PCP-degrading bacteria are obtained by acclimating activated sludge as raw material and pentachlorophenol as carbon source. In this embodiment, the preparation method of the modified biochar-based immobilized bacterial agent includes the following steps: (1) Screening of PCP-degrading bacteria and preparation of bacterial suspension (1.1) Screening of PCP-degrading bacteria 5 mL of activated sludge from a municipal sewage treatment plant was added to a conical flask containing 95 mL of inorganic salt culture medium. The bacteria were then acclimated in inorganic salt culture medium with PCP concentrations of 5 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, respectively. This acclimation was carried out in a constant temperature shaker at a speed of 150 r / min and a temperature of 30°C. Each acclimation cycle lasted two weeks to obtain a bacterial solution. An inorganic salt solid culture medium with a PCP concentration of 50 mg / L was prepared. The above bacterial solution was gradiently diluted in an ultra-clean workbench and evenly spread on the inorganic salt solid culture medium. The bacteria were then transferred to a constant temperature incubator at 30°C for cultivation. After colonies grew, the fastest-growing and largest single colony was picked and streaked onto the inorganic salt solid culture medium to obtain a single strain capable of degrading PCP. This PCP-degrading bacteria was isolated and purified, and stored in a test tube (i.e., slant culture medium) for future use.
[0030] The PCP degradation bacteria were subjected to degradation experiments to determine their degradation ability. The PCP degradation bacteria were named PCP degradation bacteria RB1, which belongs to Rhizobium Rhizobium spp.
[0031] In this step, the PCP-degrading bacteria RB1 were the free bacteria used in control group 1 and control group 2.
[0032] (1.2) Preparation of bacterial suspension In a clean bench, PCP-degrading bacteria stored in a test tube were picked with a sterile inoculating loop and inoculated into beef extract peptone medium containing PCP. The medium was then placed in a water bath constant temperature shaking box at a speed of 150 r / min and a temperature of 30°C for activation culture for 72 hours to obtain a bacterial solution. The bacterial solution was transferred to a 50 mL centrifuge tube and centrifuged to collect the bacteria. After washing twice with sterilized inorganic salt medium, it was prepared into a bacterial suspension with an OD600 of 0.5.
[0033] In the present invention, the beef extract peptone culture medium is formulated as follows: 5 g sodium chloride, 5 g beef extract, and 10 g peptone, which are dissolved and then diluted to a 1 L volumetric flask, and the pH is adjusted to 7.2.
[0034] In the present invention, the inorganic salt culture medium is prepared by the following method: S1. FeCl3·6H2O solution: Weigh 0.042 g of FeCl3·6H2O using an electronic balance, dissolve it in a 50 mL beaker with an appropriate amount of ultrapure water, and then dilute to a 100 mL volumetric flask. S2. Trace element solution: Use an electronic balance to accurately weigh 34.70 mg of (NH4)MoO2·7H2O, 44.70 mg of MnSO4·H2O, and 68.60 mg of ZnSO4·7H2O. Dissolve these in a 250 mL beaker with appropriate amount of ultrapure water and dilute to a 1 L volumetric flask. S3. Phosphate buffer: Use an electronic balance to weigh 5.00 g of NH4Cl, 8.70 g of KH2PO4, 19.72 g of K2HPO4, and 33.40 g of NaHPO4. Dissolve these in a 500 mL beaker with appropriate amount of ultrapure water and dilute to a 1 L volumetric flask. S4, MgSO4·7H2O solution: Weigh 0.46 g of MgSO4·7H2O using an electronic balance, dissolve it in a 50 mL beaker with an appropriate amount of ultrapure water, and then dilute to a 100 mL volumetric flask. S5. Separately pipette 1.0 mL of FeCl3·6H2O solution, 1.0 mL of trace element solution, 3.0 mL of MgSO4·7H2O solution, and 5.0 mL of phosphate buffer solution to make the volume to 1 L to obtain the inorganic salt culture medium.
[0035] (2) Preparation of modified biochar (2.1) Wash the rice straw with ultrapure water and dry it in an oven (60°C). After drying, crush it with a crusher to obtain rice straw powder. The rice straw powder is placed in a quartz boat and placed in a tube furnace for calcination. The tube furnace is set to 600°C and heated to 600°C at a heating rate of 10°C / min under nitrogen conditions. Pyrolysis is performed for 4.5 hours to obtain biochar. After natural cooling, the tube furnace is opened and the calcined biochar is removed. Grind it in an agate mortar and pass it through a 60-mesh sieve. Then, seal it in a sealed bag and store it in a desiccator for later use.
[0036] (2.2) Prepare a 0.025 M potassium permanganate solution at a ratio of 2 g biochar to potassium permanganate solution: 100 mL. Soak the biochar obtained in step (2.1) in a beaker containing the potassium permanganate solution. Place a magnetic stirrer in the beaker and stir for 2 hours. After stirring, filter the biochar and store it in a glass dish. Dry it in an oven (60°C). Grind the dried solid in an agate mortar to obtain a mixture.
[0037] (2.3) The mixture obtained in step (2.2) was placed in a quartz boat and fired in a tube furnace at 600°C. Under nitrogen conditions, the mixture was heated to 600°C at a heating rate of 10°C / min and pyrolyzed for 4.5 hours. After firing, the mixture was taken out, ground using an agate mortar and pestle, and re-sieved through a 60-mesh sieve to obtain modified biochar.
[0038] (3) Preparation of modified biochar-based immobilized bacterial agents The modified biochar obtained in step (2.3) was placed in a conical flask and sterilized in a high-pressure sterilizer (1.5 MPa, 121°C) for 30 minutes. After the conical flask was cooled to room temperature, the bacterial suspension obtained in step (1.2) was added to the conical flask containing the modified biochar according to the mass volume ratio of the modified biochar to the bacterial suspension of 0.2 g: 20 mL. The flask was placed in a water bath constant temperature shaking box at a speed of 150 r / min and a temperature of 30°C for shaking culture for 24 hours. The PCP-degrading bacteria RB1 was fixed on the surface and inside of the modified biochar by the adsorption effect of the modified biochar to obtain a modified biochar-based immobilized bacterial agent, which was recorded as A2.
[0039] Figure 1 This is a phylogenetic tree diagram of the PCP-degrading bacteria RB1 in Example 1 of the present invention. Figure 1 It can be seen that the strain was identified as Rhizobium Rhizobium genus, and named RB1, is a new microbial strain resource for PCP pollution remediation.
[0040] Figure 2 This is a scanning electron microscope image of the modified biochar-based immobilized bacterial agent in Example 1 of the present invention. Figure 2 It can be seen that PCP-degrading bacteria RB1 was successfully loaded onto the surface and pores of the modified biochar.
[0041] Figure 3 The figure shows the removal effect of different concentrations of pentachlorophenol by the modified biochar-based immobilized bacterial agent and PCP-degrading bacteria in Example 1 of the present invention. Figure 3 As shown, compared with control group 1 (free bacteria) and control group 2 (free bacteria + sodium pyruvate), the modified biochar-based immobilized bacteria agent of the present invention combined with sodium pyruvate demonstrated superior PCP removal efficiency, with the agent being more significantly affected by PCP concentration than both free bacteria and free bacteria + sodium pyruvate. Specifically, when the initial PCP concentration was between 5 mg / L and 30 mg / L, the PCP removal efficiency of the modified biochar-based immobilized bacteria agent combined with sodium pyruvate exceeded 40%. The addition of sodium pyruvate in the present method reduces byproduct interference, preventing the production of acidic intermediates (such as lactic acid) that could inhibit the activity of PCP-degrading bacteria. Furthermore, compared with other carbon sources, sodium pyruvate offers more balanced utilization and a more gradual energy release, extending the duration of the agent's action.
[0042] Example 2 A method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent of the present invention specifically comprises degrading pentachlorophenol-containing water using different modified biochar-based immobilized bacterial agents, comprising the following steps: According to the volume ratio of modified biochar-based immobilized bacterial agent to inorganic salt culture medium containing pentachlorophenol of 1:9, different modified biochar-based immobilized bacterial agents (A1, A2, A3, A4, A5, A6) were added to 6 portions of inorganic salt culture medium containing pentachlorophenol, respectively. The initial concentration of pentachlorophenol in the inorganic salt culture medium containing pentachlorophenol was 15 mg / L and the pH value was 6. Then, sodium pyruvate was added at an amount of 300 mg per liter of inorganic salt culture medium containing pentachlorophenol. The degradation reaction was carried out at a rotation speed of 150 r / min and a temperature of 30°C for 14 days to complete the degradation of pentachlorophenol in water.
[0043] Control group 1: The modified biochar-based immobilized bacterial agent was replaced with free bacteria, i.e., PCP-degrading bacteria, and sodium pyruvate was not added. Other conditions were the same.
[0044] Control group 2: The modified biochar-based immobilized bacterial agent was replaced with free bacteria, i.e. PCP-degrading bacteria, and other conditions were the same.
[0045] After the cultivation is completed, samples are extracted and the PCP content is determined by high performance liquid chromatography (HPLC), and the removal rate of PCP by different bacterial agents is calculated. The results are as follows: Figure 4 、 5 shown.
[0046] In this embodiment, the modified biochar-based immobilized bacterial agents (A1, A3, A4, A5, A6) used were prepared by a method that was substantially the same as the method for preparing the modified biochar-based immobilized bacterial agent (A2) in Example 1, with the only difference being that in step (3), the mass volume ratio of the modified biochar to the bacterial suspension was 0.2 g:10 mL, 0.2 g:30 mL, 0.2 g:40 mL, 0.2 g:50 mL, and 0.2 g:60 mL, respectively; the modified biochar-based immobilized bacterial agents obtained were designated A1, A3, A4, A5, and A6, respectively.
[0047] Figure 4 This is a graph showing the removal effect of pentachlorophenol by different modified biochar-based immobilized bacterial agents in Example 2 of the present invention. Figure 4It can be seen that the modified biochar-based immobilized bacterial agents (A1, A2, A3, A4, A5, and A6) of the present invention all have a certain removal effect on PCP. In particular, when the mass-to-volume ratio of modified biochar to bacterial suspension is 0.2 g:20 mL, the modified biochar-based immobilized bacterial agent (A2) has the best PCP removal effect. If the mass-to-volume ratio of modified biochar to bacterial suspension is too low, the modified biochar will provide insufficient attachment sites, and some bacteria will remain free, failing to demonstrate the advantages of immobilized microorganisms. If the mass-to-volume ratio of modified biochar to bacterial suspension is too high, the investment in the prepared modified biochar will increase, which will increase economic and experimental costs and will not achieve twice the result with half the effort. Therefore, selecting an appropriate mass-to-volume ratio of modified biochar to bacterial suspension is crucial for the preparation of modified biochar-based immobilized bacterial agents.
[0048] Figure 5 The figure shows the effect of PCP degradation bacteria on pentachlorophenol removal under different treatment conditions in Example 2 of the present invention. Figure 5 It can be seen that the addition of sodium pyruvate as an auxiliary carbon source significantly improved the PCP removal efficiency of free bacteria (PCP-degrading bacteria) compared to that of free bacteria (PCP-degrading bacteria) alone. After 14 days of incubation, the removal efficiency of pentachlorophenol by free bacteria (PCP-degrading bacteria) was only 16.18%, while the removal efficiency of free bacteria + sodium pyruvate reached 45.99%. This is because the addition of sodium pyruvate provides additional energy for the free bacteria (PCP-degrading bacteria), promoting the proliferation of the degrading bacteria and increasing their metabolic activity, thereby enhancing PCP removal. This also indirectly reflects the necessity of adding sodium pyruvate during the removal of PCP using modified biochar-based immobilized bacteria.
[0049] Example 3 A method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent of the present invention, specifically using a modified biochar-based immobilized bacterial agent to degrade pentachlorophenol-containing water bodies at different pH values, comprising the following steps: According to the volume ratio of the modified biochar-based immobilized bacterial agent to the inorganic salt culture medium containing pentachlorophenol of 1:9, the modified biochar-based immobilized bacterial agent (A2) prepared in Example 1 was added to 5 portions of inorganic salt culture medium containing pentachlorophenol with an initial concentration of 15 mg / L of pentachlorophenol, and the initial pH values of the inorganic salt culture medium containing pentachlorophenol were 3, 4, 5, 6, and 7, respectively; sodium pyruvate was then added in an amount of 300 mg per liter of inorganic salt culture medium containing pentachlorophenol, and the degradation reaction was carried out at a rotation speed of 150 r / min and a temperature of 30°C for 14 days to complete the degradation of pentachlorophenol in the water.
[0050] Control group 1: The modified biochar-based immobilized bacterial agent was replaced with free bacteria, i.e., PCP-degrading bacteria, and sodium pyruvate was not added. Other conditions were the same.
[0051] Control group 2: The modified biochar-based immobilized bacterial agent was replaced with free bacteria, i.e. PCP-degrading bacteria, and other conditions were the same.
[0052] After the cultivation is completed, samples are extracted and the PCP content is determined by high performance liquid chromatography (HPLC), and the removal rate of PCP by different bacterial agents is calculated. The results are as follows: Figure 6 shown.
[0053] Figure 6 The figure shows the removal effect of pentachlorophenol by the modified biochar-based immobilized bacterial agent and PCP-degrading bacteria at different pH values in Example 3 of the present invention. Figure 6 It can be seen that different pH values have a certain impact on the PCP removal efficiency of free bacteria, free bacteria + sodium pyruvate, and modified biochar-based immobilized bacteria + sodium pyruvate. At pH values of 3 to 7, the PCP removal efficiency of the modified biochar-based immobilized bacteria + sodium pyruvate remained above 40%. At pH 5, the modified biochar-based immobilized bacteria + sodium pyruvate achieved the best PCP removal efficiency, reaching 57%, maintaining its good removal efficiency compared to free bacteria and free bacteria + sodium pyruvate. This shows that the modified biochar-based immobilized bacteria of the present invention have the ability to withstand extreme environments and maintain activity over a wide pH range of 3 to 7, effectively removing PCP.
[0054] Example 4 A method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent of the present invention, specifically using a modified biochar-based immobilized bacterial agent to degrade pentachlorophenol-containing water under the coexistence of different concentrations of Cd(II), comprising the following steps: According to the volume ratio of the modified biochar-based immobilized bacterial agent to the inorganic salt culture medium containing pentachlorophenol being 1:9, the modified biochar-based immobilized bacterial agent (A2) prepared in Example 1 was added to 5 portions of the inorganic salt culture medium containing pentachlorophenol with an initial pentachlorophenol concentration of 15 mg / L and a pH of 6, and Cd(II) was added to adjust the Cd(II) concentrations in the inorganic salt culture medium containing pentachlorophenol to 0 mg / L, 3 mg / L, 5 mg / L, 10 mg / L, and 15 mg / L, respectively. Sodium pyruvate was then added in an amount of 300 mg per liter of the inorganic salt culture medium containing pentachlorophenol. The degradation reaction was carried out at a rotation speed of 150 r / min and a temperature of 30°C for 14 days to complete the degradation of pentachlorophenol in the water body.
[0055] Control group 1: The modified biochar-based immobilized bacterial agent was replaced with free bacteria, i.e., PCP-degrading bacteria, and sodium pyruvate was not added. Other conditions were the same.
[0056] Control group 2: The modified biochar-based immobilized bacterial agent was replaced with free bacteria, i.e. PCP-degrading bacteria, and other conditions were the same.
[0057] After the cultivation is completed, samples are extracted and the PCP content is determined by high performance liquid chromatography (HPLC), and the removal rate of PCP by different bacterial agents is calculated. The results are as follows: Figure 7 shown.
[0058] Figure 7 This is a graph showing the removal effect of pentachlorophenol by the modified biochar-based immobilized bacterial agent and PCP-degrading bacteria in Example 4 of the present invention under the coexistence of different concentrations of Cd(II). Figure 7 It can be seen that when Cd(Ⅱ) is present in water, the PCP removal efficiency of free bacteria, free bacteria + sodium pyruvate, and modified biochar-based immobilized bacteria + sodium pyruvate all has a certain impact. Compared with the absence of coexisting Cd(Ⅱ), the PCP removal efficiency of free bacteria and free bacteria + sodium pyruvate is improved when the Cd(Ⅱ) concentration is 3 mg / L to 15 mg / L, indicating that the PCP-degrading bacteria still maintain excellent activity under the coexistence of Cd(Ⅱ). Cd(Ⅱ) may stimulate the synthesis of microorganisms, enhance the activity of degradation enzymes, and promote PCP removal. The modified biochar-based immobilized bacterial agent of the present invention can still maintain effective removal of PCP when the Cd(II) concentration is 3 mg / L to 15 mg / L. In particular, when the Cd(II) concentration is 3 mg / L, the removal rate reaches 50%, which is the best removal effect. This shows that low concentrations of Cd(II) can stimulate the synthesis of microorganisms, upregulate the expression of dechlorinase genes, and provide support for the removal of PCP. However, when the Cd(II) concentration is 15 mg / L, the removal effect of the modified biochar-based immobilized bacterial agent + sodium pyruvate on PCP is reduced. This is because Cd(II) occupies the adsorption sites on the biochar and high concentrations of Cd(II) inhibit the activity of degrading bacteria, thereby affecting the removal effect of PCP.
[0059] In summary, the method of removing pentachlorophenol in water by using modified biochar-based immobilized bacterial agents of the present invention, on the one hand, compared with other bacterial agents, the PCP-degrading bacteria RB1 used in the present invention has good tolerance and biological activity, can degrade PCP into low-toxic or non-toxic metabolites, which is beneficial to the removal of PCP; on the other hand, the modified biochar has a large specific surface area and strong adsorption capacity, which can promote PCP to migrate to the modified biochar. When the PCP-degrading bacteria RB1 is fixed on the modified biochar, the PCP-degrading bacteria RB1 can not only use PCP and biochar as carbon sources, but also can effectively remove PCP from the water. The PCP-degrading bacteria RB1 are increased in value, and are concentrated in the modified biochar at a high density to maintain their activity, thereby increasing the biomass and metabolic activity of the degrading bacteria. The modified biochar can also provide a sheltered microenvironment for the PCP-degrading bacteria RB1, protecting it from the impact of external environmental factors, and maintaining the biological activity and tolerance of the PCP-degrading bacteria RB1, thereby increasing the concentration of microbial cells and their ability to resist environmental impacts. More importantly, by adding sodium pyruvate, additional energy can be provided for the PCP-degrading bacteria RB1, promoting its further value-added and increasing its metabolic activity, ultimately achieving good removal of pentachlorophenol in water. The method of the present invention has the advantages of simple process, easy operation, low processing cost, good removal rate, etc., high practical value, good application prospects, and is a novel, green and environmentally friendly method for removing pentachlorophenol in water.
[0060] The above description is only a preferred embodiment of the present invention and does not constitute any formal limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent, characterized in that: The method utilizes a modified biochar-based immobilized bacterial agent to degrade pentachlorophenol-containing water; the modified biochar-based immobilized bacterial agent uses modified biochar as a carrier, and the modified biochar is loaded with PCP-degrading bacteria; the PCP-degrading bacteria are obtained after acclimation using activated sludge as a raw material and pentachlorophenol as a carbon source.
2. The method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent according to claim 1, characterized in that: The method for screening PCP-degrading bacteria comprises the following steps: acclimating activated sludge in a pentachlorophenol-containing culture medium with pentachlorophenol concentrations of 5 mg / L, 15 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L, and obtaining PCP-degrading bacteria through separation and purification; each cycle in the acclimation process is 14 days, the acclimation temperature is 30° C. to 35° C., the pentachlorophenol-containing culture medium further comprises an inorganic salt culture medium, and the activated sludge is activated sludge from a municipal sewage treatment plant.
3. The method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent according to claim 2, characterized in that: The preparation method of the modified biochar-based immobilized bacterial agent comprises the following steps: (1) Activating and culturing PCP-degrading bacteria to obtain a bacterial suspension; (2) The bacterial suspension obtained in step (1) is mixed with the modified biochar and cultured to obtain a modified biochar-based immobilized bacterial agent.
4. The method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent according to claim 3, characterized in that: In step (2), the mass volume ratio of the modified biochar to the bacterial suspension is 0.2 g: 10 mL to 60 mL, and the OD600 of the bacterial suspension is 0.45 to 0.
55.
5. The method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent according to claim 3, characterized in that: In step (1), the temperature during the activation culture process is controlled at 30°C to 35°C, and the activation culture time is 72h to 96h; In step (2), the temperature during the culture process is controlled at 30°C to 35°C, and the culture time is 24h to 36h.
6. The method for removing pentachlorophenol in water using a modified biochar-based immobilized bacterial agent according to claim 3, characterized in that: In step (2), the method for preparing the modified biochar comprises the following steps: (2.1) Pyrolyzing biomass materials to obtain biochar; (2.2) mixing the biochar obtained in step (2.1) and the potassium permanganate solution, and drying to obtain a mixture; (2.3) Pyrolyzing the mixture obtained in step (2.2) to obtain modified biochar.
7. The method for removing pentachlorophenol in water using a modified biochar-based immobilized bacterial agent according to claim 6, characterized in that: In step (2.1), the biomass material is rice straw, the pyrolysis is carried out under an inert atmosphere or nitrogen, the heating rate during the pyrolysis process is 10°C / min, the pyrolysis temperature is 600°C, and the pyrolysis time is 4.5 hours; In step (2.2), the mass volume ratio of the biochar to the potassium permanganate solution is 2 g:100 mL, the concentration of the potassium permanganate solution is 0.025 M, and the mixing is performed under stirring for 2 h. In step (2.3), the pyrolysis is carried out under an inert atmosphere or nitrogen, the heating rate during the pyrolysis process is 10°C / min, the pyrolysis temperature is 600°C, and the pyrolysis time is 4.5 hours.
8. The method for removing pentachlorophenol from water using a modified biochar-based immobilized bacterial agent according to any one of claims 1 to 7, characterized in that: The degradation treatment specifically comprises: mixing the modified biochar-based immobilized bacterial agent with water containing pentachlorophenol, adding sodium pyruvate, and carrying out a degradation reaction to achieve degradation of the pentachlorophenol in the water.
9. The method for removing pentachlorophenol in water using a modified biochar-based immobilized bacterial agent according to claim 8, characterized in that: The volume ratio of the modified biochar-based immobilized bacterial agent to the pentachlorophenol-containing water body is 1:9, and the addition amount of the sodium pyruvate is 300 mg to 320 mg per liter of the pentachlorophenol-containing water body.
10. The method for removing pentachlorophenol in water using a modified biochar-based immobilized bacterial agent according to claim 9, characterized in that: The initial concentration of pentachlorophenol in the pentachlorophenol-containing water body is 5 mg / L to 120 mg / L, the initial pH value of the pentachlorophenol-containing water body is 3 to 7, the pentachlorophenol-containing water body further contains divalent cadmium, the concentration of divalent cadmium in the pentachlorophenol-containing water body is ≤15 mg / L, the temperature of the degradation reaction is 30° C. to 35° C., and the time of the degradation reaction is ≥14 days.