Method for combined microbial treatment of heavy metal wastewater

Abstract

The application discloses a method for treating heavy metal sewage by using microorganisms, and adopts a microorganism-containing treatment agent to treat the heavy metal sewage, wherein the microorganism-containing treatment agent comprises a microorganism preparation and an adsorbent, the microorganism preparation is a zooglea preparation, and the adsorbent is bentonite-based adsorbent particles. The method can remove heavy metal ions in the sewage, reduce the heavy metal pollution degree of the sewage, and shorten the treatment time, thereby improving the sewage treatment efficiency.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for the combined treatment of heavy metal wastewater using microorganisms. Background Technology

[0002] Wastewater contains various harmful chemicals such as heavy metals, organic pollutants, bacteria, and suspended solids. Direct discharge without treatment will severely impact aquatic ecosystems. Biological treatment technologies are widely used in wastewater treatment due to their cost-effectiveness and environmental friendliness. Among these, Bdellovibrio bacterium, smaller than bacteria, can pass through bacterial filters, acting similarly to bacteriophages. However, it is not a virus; it is a type of bacteria that can "eat" bacteria, a type of Gram-negative bacterium that parasitizes other bacteria and causes their lysis. This bacterium can quickly eliminate bacteria of the genera *Salmonella*, *Shigella*, *Proteus*, *Pseudomonas*, *Escherichia*, *Erwinia*, and *Vibrio*, thus eliminating pathogens and controlling or reducing their pollution of environmental water sources. Because Bdellovibrio can lyse multiple bacteria and has a unique lifestyle with ecological advantages, it is considered one of the biological agents of natural purification and has been developed and applied as a novel microecological agent in the field of microecological research. Summary of the Invention

[0003] To address this issue, the present invention provides a method for the combined microbial treatment of heavy metal wastewater. The method employs a microbial treatment agent to treat heavy metal wastewater, wherein the microbial treatment agent comprises a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0004] (1) Inoculate the Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension onto LB medium and culture at 32±2℃ for 50-100h. After culture, pick a single spot and immerse it in sterile water, centrifuge, and then inoculate it into agar medium for continuous subculturing for 3-5 generations to activate it. When phage plaques appear, pick the phage plaques into sterile water, centrifuge to separate them, and take the supernatant to remove Escherichia coli with a bacterial filter to obtain Bdellovibrio agent;

[0005] (2) Prepare an aqueous solution of sodium carbonate and an aqueous solution of fulvic acid; add bentonite to the aqueous solution of sodium carbonate under stirring; after the addition is completed, heat the solution in a water bath to 60±5℃ and stir for more than 30 minutes; after stirring, separate the solid and liquid phases; wash the solid phase with deionized water more than 3 times and dry it to obtain a pretreated powder; add the pretreated powder to the aqueous solution of fulvic acid; after the addition is completed, stir for more than 30 minutes; then add hexadecyltrimethylammonium bromide to the solution under stirring; after the addition is completed, continue stirring for more than 5 hours; then separate the solid and liquid phases; wash the solid phase with deionized water more than 3 times and dry it to obtain fulvic acid modified particles;

[0006] (3) Add the fulvic acid modified particles to deionized water and stir under ultrasonic conditions for more than 20 minutes to obtain a suspension; stir the suspension and then add glyphosate to the suspension while stirring. After the addition is completed, adjust the pH of the suspension to 10-11 with sodium hydroxide solution and then stir for more than 8 hours; after stirring, separate the solid and liquid phases, wash the solid phase with deionized water more than 3 times, and dry it to obtain bentonite-based adsorption particles.

[0007] (4) Add the Bdellovibrio agent to the wastewater, heat it to 35±3℃ and stir for more than 20 minutes, then add the bentonite-based adsorbent particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 to 2 hours to complete the treatment of heavy metal wastewater.

[0008] Further, in step (1), the LB medium contains 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder is sterile distilled water.

[0009] Further, in step (2), the concentration of sodium carbonate in the aqueous solution is 2-3 g / 100 mL, and the solvent is water; the concentration of fulvic acid in the aqueous solution is 0.8-1.4 g / 100 mL, and the solvent is water; the mass ratio of bentonite added to the aqueous solution of sodium carbonate is bentonite:sodium carbonate aqueous solution = 1:50-100; the mass ratio of pretreated powder added to the aqueous solution of fulvic acid is pretreated powder:hydrated solution of fulvic acid = 1:100; the mass ratio of hexadecyltrimethylammonium bromide added to the mass ratio of the added pretreated powder is hexadecyltrimethylammonium bromide:pretreated powder = 3-4:1.

[0010] Further, in step (3), the mass ratio of the fulvic acid modified particles to deionized water is fulvic acid modified particles: deionized water = 1:1000; the mass ratio of the added glyphosate to the added fulvic acid modified particles is glyphosate: fulvic acid modified particles = 1~2:1.

[0011] Furthermore, in step (3), the concentration of the solute in the sodium hydroxide solution is 1.5–2 mol / L, and the solvent is water.

[0012] Further, in step (4), the mass ratio of the added Bdellovibrio agent and bentonite-based adsorbent particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorbent particles: wastewater = 2-2.5g: 0.2-0.3g: 500mL.

[0013] The beneficial effects of this invention are as follows: the method described in this invention can effectively remove heavy metal ions from wastewater, reducing the degree of heavy metal pollution in wastewater; and the treatment time is significantly shortened, improving wastewater treatment efficiency. This invention significantly improves the removal rate of heavy metals by introducing microbial agents into traditional adsorbent treatment processes. This is mainly because wastewater inevitably contains a large number of bacteria and other microorganisms. Traditional adsorbents cannot effectively prevent the adhesion of bacteria to the adsorbent surface, often resulting in a large number of adsorption sites on the surface of traditional adsorbents being covered by bacteria or other microorganisms, making their adsorption effect on heavy metals poor. This invention introduces a bactericidal agent, Bdellovibrio, which significantly reduces the adsorption of bacteria and other microorganisms on the adsorbent surface, thereby improving the adsorption and removal effect of the adsorbent on heavy metal ions. Furthermore, this invention improves and optimizes the preparation method of traditional bentonite-based adsorbents by introducing fulvic acid groups onto the bentonite surface and simultaneously modifying it with glyphosate grafting, thereby improving the adsorption and chelation effect of the adsorbent on heavy metal ions, macroscopically manifested as an improvement in the removal rate of heavy metal ions in wastewater. Detailed Implementation

[0014] The present invention will be further described below with reference to the embodiments.

[0015] Example 1

[0016] A method for combined microbial treatment of heavy metal wastewater involves using a microbial treatment agent to treat the wastewater. The microbial treatment agent includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0017] (1) Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension were inoculated onto LB medium. The LB medium contained 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder was sterile distilled water. The medium was incubated at 32±2℃ for 80 h. After incubation, single spots were picked, immersed in sterile water, centrifuged, and then inoculated into agar medium for four consecutive passages to activate the phage plaques. The agar medium contained 0.3% beef extract, 1% peptone, 0.5% sodium chloride, 2% agar, and the remainder was sterile distilled water. The phage plaques were picked into sterile water, centrifuged, and the supernatant was used to remove Escherichia coli using a bacterial filter to obtain the Bdellovibrio agent.

[0018] (2) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 2 g / 100 mL and the solvent is water; prepare an aqueous solution of fulvic acid, wherein the concentration of fulvic acid in the aqueous solution is 0.8 g / 100 mL and the solvent is water; add bentonite to the aqueous solution of sodium carbonate under stirring, wherein the mass ratio of bentonite added to the aqueous solution of sodium carbonate is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain a pre-solidified solution. The pretreated powder is added to an aqueous solution of fulvic acid at a mass ratio of pretreated powder to aqueous solution of fulvic acid of 1:100. After addition, the mixture is stirred for 30 min. Then, hexadecyltrimethylammonium bromide is added to the solution while stirring, at a mass ratio of hexadecyltrimethylammonium bromide to pretreated powder of 3:1. After addition, stirring is continued for 5 h. Then, solid-liquid separation is performed. The solid phase is washed three times with deionized water and dried at 60 °C for 3 h to obtain fulvic acid modified particles.

[0019] (3) The fulvic acid modified particles were added to deionized water at a mass ratio of fulvic acid modified particles to deionized water of 1:1000. The mixture was stirred for 20 minutes under ultrasonic conditions to obtain a suspension. The suspension was stirred, and then glyphosate was added to the suspension while stirring. The mass ratio of glyphosate added to fulvic acid modified particles was 1:1. After the addition was completed, the pH of the suspension was adjusted to 10 with sodium hydroxide solution, and then stirred for 8 hours. The concentration of solute in the sodium hydroxide solution was 1.5 mol / L, and the solvent was water. After stirring, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain bentonite-based adsorbent particles.

[0020] (4) Add the Bdellovibrio agent to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 20 min, then add the bentonite-based adsorbent particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 h to complete the heavy metal wastewater treatment. The mass ratio of the added Bdellovibrio agent and bentonite-based adsorbent particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorbent particles: wastewater = 2 g: 0.2 g: 500 mL.

[0021] Example 2

[0022] A method for combined microbial treatment of heavy metal wastewater involves using a microbial treatment agent to treat the wastewater. The microbial treatment agent includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0023] (1) Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension were inoculated onto LB medium. The LB medium contained 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder was sterile distilled water. The medium was incubated at 32±2℃ for 80 h. After incubation, single spots were picked, immersed in sterile water, centrifuged, and then inoculated into agar medium for four consecutive passages to activate the phage plaques. The agar medium contained 0.3% beef extract, 1% peptone, 0.5% sodium chloride, 2% agar, and the remainder was sterile distilled water. The phage plaques were picked into sterile water, centrifuged, and the supernatant was used to remove Escherichia coli using a bacterial filter to obtain the Bdellovibrio agent.

[0024] (2) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 2 g / 100 mL and the solvent is water; prepare an aqueous solution of fulvic acid, wherein the concentration of fulvic acid in the aqueous solution is 1 g / 100 mL and the solvent is water; add bentonite to the aqueous solution of sodium carbonate under stirring, wherein the mass ratio of bentonite added to the aqueous solution of sodium carbonate is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain the pretreated solution. The pretreated powder is added to an aqueous solution of fulvic acid at a mass ratio of 1:100. After addition, the mixture is stirred for 30 minutes. Then, hexadecyltrimethylammonium bromide is added to the solution while stirring, at a mass ratio of 3:1. After addition, stirring is continued for 5 hours. Then, solid-liquid separation is performed. The solid phase is washed three times with deionized water and dried at 60°C for 3 hours to obtain fulvic acid-modified particles.

[0025] (3) The fulvic acid modified particles were added to deionized water at a mass ratio of fulvic acid modified particles to deionized water of 1:1000. The mixture was stirred for 20 minutes under ultrasonic conditions to obtain a suspension. The suspension was stirred, and then glyphosate was added to the suspension while stirring. The mass ratio of glyphosate added to fulvic acid modified particles was 1:1. After the addition was completed, the pH of the suspension was adjusted to 10 with sodium hydroxide solution, and then stirred for 8 hours. The concentration of solute in the sodium hydroxide solution was 1.5 mol / L, and the solvent was water. After stirring, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain bentonite-based adsorbent particles.

[0026] (4) Add the Bdellovibrio agent to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 20 min, then add the bentonite-based adsorbent particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 h to complete the heavy metal wastewater treatment. The mass ratio of the added Bdellovibrio agent and bentonite-based adsorbent particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorbent particles: wastewater = 2.2 g: 0.2 g: 500 mL.

[0027] Example 3

[0028] A method for combined microbial treatment of heavy metal wastewater involves using a microbial treatment agent to treat the wastewater. The microbial treatment agent includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0029] (1) Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension were inoculated onto LB medium. The LB medium contained 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder was sterile distilled water. The medium was incubated at 32±2℃ for 80 h. After incubation, single spots were picked, immersed in sterile water, centrifuged, and then inoculated into agar medium for four consecutive passages to activate the phage plaques. The agar medium contained 0.3% beef extract, 1% peptone, 0.5% sodium chloride, 2% agar, and the remainder was sterile distilled water. The phage plaques were picked into sterile water, centrifuged, and the supernatant was used to remove Escherichia coli using a bacterial filter to obtain the Bdellovibrio agent.

[0030] (2) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 3 g / 100 mL and the solvent is water; prepare an aqueous solution of fulvic acid, wherein the concentration of fulvic acid in the aqueous solution is 1.2 g / 100 mL and the solvent is water; add bentonite to the aqueous solution of sodium carbonate under stirring, wherein the mass ratio of bentonite added to the aqueous solution of sodium carbonate is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain a pre-solidified solution. The pretreated powder is added to an aqueous solution of fulvic acid at a mass ratio of pretreated powder to aqueous solution of fulvic acid of 1:100. After addition, the mixture is stirred for 30 min. Then, hexadecyltrimethylammonium bromide is added to the solution while stirring, at a mass ratio of hexadecyltrimethylammonium bromide to pretreated powder of 4:1. After addition, stirring is continued for 5 h. Then, solid-liquid separation is performed. The solid phase is washed three times with deionized water and dried at 60 °C for 3 h to obtain fulvic acid-modified particles.

[0031] (3) The fulvic acid modified particles were added to deionized water at a mass ratio of fulvic acid modified particles to deionized water of 1:1000. The mixture was stirred for 20 minutes under ultrasonic conditions to obtain a suspension. The suspension was stirred, and then glyphosate was added to the suspension while stirring. The mass ratio of glyphosate added to fulvic acid modified particles was 2:1. After the addition was completed, the pH of the suspension was adjusted to 10 with sodium hydroxide solution, and then stirred for 8 hours. The concentration of solute in the sodium hydroxide solution was 1.5 mol / L, and the solvent was water. After stirring, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain bentonite-based adsorbent particles.

[0032] (4) Add the Bdellovibrio agent to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 20 min, then add the bentonite-based adsorption particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 h to complete the heavy metal wastewater treatment. The mass ratio of the added Bdellovibrio agent and bentonite-based adsorption particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorption particles: wastewater = 2.4 g: 0.3 g: 500 mL.

[0033] Example 4

[0034] A method for combined microbial treatment of heavy metal wastewater involves using a microbial treatment agent to treat the wastewater. The microbial treatment agent includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0035] (1) Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension were inoculated onto LB medium. The LB medium contained 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder was sterile distilled water. The medium was incubated at 32±2℃ for 80 h. After incubation, single spots were picked, immersed in sterile water, centrifuged, and then inoculated into agar medium for four consecutive passages to activate the phage plaques. The agar medium contained 0.3% beef extract, 1% peptone, 0.5% sodium chloride, 2% agar, and the remainder was sterile distilled water. The phage plaques were picked into sterile water, centrifuged, and the supernatant was used to remove Escherichia coli using a bacterial filter to obtain the Bdellovibrio agent.

[0036] (2) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 3 g / 100 mL and the solvent is water; prepare an aqueous solution of fulvic acid, wherein the concentration of fulvic acid in the aqueous solution is 1.4 g / 100 mL and the solvent is water; add bentonite to the aqueous solution of sodium carbonate under stirring, wherein the mass ratio of bentonite added to the aqueous solution of sodium carbonate is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain a pre-solidified solution. The pretreated powder is added to an aqueous solution of fulvic acid at a mass ratio of pretreated powder to aqueous solution of fulvic acid of 1:100. After addition, the mixture is stirred for 30 min. Then, hexadecyltrimethylammonium bromide is added to the solution while stirring, at a mass ratio of hexadecyltrimethylammonium bromide to pretreated powder of 4:1. After addition, stirring is continued for 5 h. Then, solid-liquid separation is performed. The solid phase is washed three times with deionized water and dried at 60 °C for 3 h to obtain fulvic acid-modified particles.

[0037] (3) The fulvic acid modified particles were added to deionized water at a mass ratio of fulvic acid modified particles to deionized water of 1:1000. The mixture was stirred for 20 minutes under ultrasonic conditions to obtain a suspension. The suspension was stirred, and then glyphosate was added to the suspension while stirring. The mass ratio of glyphosate added to fulvic acid modified particles was 2:1. After the addition was completed, the pH of the suspension was adjusted to 10 with sodium hydroxide solution, and then stirred for 8 hours. The concentration of solute in the sodium hydroxide solution was 1.5 mol / L, and the solvent was water. After stirring, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain bentonite-based adsorbent particles.

[0038] (4) Add the Bdellovibrio agent to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 20 min, then add the bentonite-based adsorption particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 h to complete the heavy metal wastewater treatment. The mass ratio of the added Bdellovibrio agent and bentonite-based adsorption particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorption particles: wastewater = 2.5 g: 0.3 g: 500 mL.

[0039] Comparative Example 1

[0040] A method for combined microbial treatment of heavy metal wastewater involves using a microbial treatment agent to treat the wastewater. The microbial treatment agent includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0041] (1) Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension were inoculated onto LB medium. The LB medium contained 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder was sterile distilled water. The medium was incubated at 32±2℃ for 80 h. After incubation, single spots were picked, immersed in sterile water, centrifuged, and then inoculated into agar medium for four consecutive passages to activate the phage plaques. The agar medium contained 0.3% beef extract, 1% peptone, 0.5% sodium chloride, 2% agar, and the remainder was sterile distilled water. The phage plaques were picked into sterile water, centrifuged, and the supernatant was used to remove Escherichia coli using a bacterial filter to obtain the Bdellovibrio agent.

[0042] (2) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 2 g / 100 mL, and the solvent is water; add bentonite to the aqueous solution of sodium carbonate while stirring, wherein the mass ratio of bentonite to sodium carbonate aqueous solution is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, and after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain a pretreated powder; add deionized water to the pretreated powder. In water, the mass ratio of pretreated powder to deionized water was 1:100. After the addition was completed, the mixture was stirred for 30 minutes. Then, hexadecyltrimethylammonium bromide was added to the solution while stirring. The mass ratio of the added hexadecyltrimethylammonium bromide to the added pretreated powder was 3:1. After the addition was completed, the mixture was stirred for another 5 hours. Then, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain the post-treated particles of this comparative example.

[0043] (3) The post-processed particles were added to deionized water at a mass ratio of 1:1000. The mixture was stirred for 20 minutes under ultrasonic conditions to obtain a suspension. The suspension was stirred, and then glyphosate was added to the suspension while stirring. The mass ratio of glyphosate added to the post-processed particles was 1:1. After the addition was completed, the pH of the suspension was adjusted to 10 with sodium hydroxide solution, and then stirred for 8 hours. The concentration of solute in the sodium hydroxide solution was 1.5 mol / L, and the solvent was water. After stirring, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain bentonite-based adsorbent particles.

[0044] (4) Add the Bdellovibrio agent to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 20 min, then add the bentonite-based adsorbent particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 h to complete the heavy metal wastewater treatment. The mass ratio of the added Bdellovibrio agent and bentonite-based adsorbent particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorbent particles: wastewater = 2.2 g: 0.2 g: 500 mL.

[0045] Comparative Example 2

[0046] A method for combined microbial treatment of heavy metal wastewater involves using a microbial treatment agent to treat the wastewater. The microbial treatment agent includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles. The treatment steps include:

[0047] (1) Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension were inoculated onto LB medium. The LB medium contained 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder was sterile distilled water. The medium was incubated at 32±2℃ for 80 h. After incubation, single spots were picked, immersed in sterile water, centrifuged, and then inoculated into agar medium for four consecutive passages to activate the phage plaques. The agar medium contained 0.3% beef extract, 1% peptone, 0.5% sodium chloride, 2% agar, and the remainder was sterile distilled water. The phage plaques were picked into sterile water, centrifuged, and the supernatant was used to remove Escherichia coli using a bacterial filter to obtain the Bdellovibrio agent.

[0048] (2) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 2 g / 100 mL and the solvent is water; prepare an aqueous solution of fulvic acid, wherein the concentration of fulvic acid in the aqueous solution is 1 g / 100 mL and the solvent is water; add bentonite to the aqueous solution of sodium carbonate under stirring, wherein the mass ratio of bentonite added to the aqueous solution of sodium carbonate is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain a pretreated powder. The pretreated powder was added to the aqueous solution of fulvic acid, with a mass ratio of pretreated powder to aqueous solution of fulvic acid of 1:100. After addition, the mixture was stirred for 30 minutes. Then, hexadecyltrimethylammonium bromide was added to the solution while stirring, with a mass ratio of hexadecyltrimethylammonium bromide to pretreated powder of 3:1. After addition, stirring was continued for 5 hours. Then, solid-liquid separation was performed. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain the bentonite-based adsorbent particles of this comparative example.

[0049] (3) Add the Bdellovibrio agent to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 20 min, then add the bentonite-based adsorption particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 h to complete the heavy metal wastewater treatment. The mass ratio of the added Bdellovibrio agent and bentonite-based adsorption particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorption particles: wastewater = 2.2 g: 0.2 g: 500 mL.

[0050] Blank control group

[0051] A method for treating heavy metal wastewater uses bentonite-based adsorption particles, and the treatment steps include:

[0052] (1) Prepare an aqueous solution of sodium carbonate, wherein the concentration of sodium carbonate in the aqueous solution is 2 g / 100 mL and the solvent is water; prepare an aqueous solution of fulvic acid, wherein the concentration of fulvic acid in the aqueous solution is 1 g / 100 mL and the solvent is water; add bentonite to the aqueous solution of sodium carbonate under stirring, wherein the mass ratio of bentonite added to the aqueous solution of sodium carbonate is 1:50; after the addition is completed, heat the solution in a water bath to 60°C, keep it warm and stir for 30 min, after stirring, separate the solid and liquid phases, wash the solid phase three times with deionized water, and dry it at 60°C for 3 h to obtain the pretreated solution. The pretreated powder is added to an aqueous solution of fulvic acid at a mass ratio of 1:100. After addition, the mixture is stirred for 30 minutes. Then, hexadecyltrimethylammonium bromide is added to the solution while stirring, at a mass ratio of 3:1. After addition, stirring is continued for 5 hours. Then, solid-liquid separation is performed. The solid phase is washed three times with deionized water and dried at 60°C for 3 hours to obtain fulvic acid-modified particles.

[0053] (2) The fulvic acid modified particles were added to deionized water at a mass ratio of fulvic acid modified particles to deionized water of 1:1000. The mixture was stirred for 20 minutes under ultrasonic conditions to obtain a suspension. The suspension was stirred, and then glyphosate was added to the suspension while stirring. The mass ratio of glyphosate added to fulvic acid modified particles was 1:1. After the addition was completed, the pH of the suspension was adjusted to 10 with sodium hydroxide solution, and then stirred for 8 hours. The concentration of solute in the sodium hydroxide solution was 1.5 mol / L, and the solvent was water. After stirring, the solid and liquid phases were separated. The solid phase was washed three times with deionized water and dried at 60°C for 3 hours to obtain bentonite-based adsorbent particles.

[0054] (3) Add the bentonite-based adsorbent particles to the test wastewater (copper ion concentration of 150 mg / L, pH of 5), heat to 35±3℃ and stir for 1 hour and 20 minutes to complete the heavy metal wastewater treatment; the ratio of the added mass of the bentonite-based adsorbent particles to the volume of the wastewater is bentonite-based adsorbent particles: wastewater = 0.2 g: 500 mL.

[0055] Example 5

[0056] The removal rates of copper ions after wastewater treatment in the above embodiments and comparative examples are shown in Table 1. Removal rate = (copper ion concentration before treatment - copper ion concentration after treatment) / copper ion concentration before treatment × 100%.

[0057] As shown in Table 1, the method described in this invention can effectively remove heavy metal ions from wastewater, reducing the degree of heavy metal pollution; and the treatment time is significantly shortened, improving wastewater treatment efficiency. Comparison of Example 2 and various comparative examples shows that introducing microbial agents into traditional adsorbent treatment processes can significantly improve the removal rate of heavy metals. This is mainly because wastewater inevitably contains a large number of bacteria and other microorganisms. Traditional adsorbents cannot effectively prevent bacterial adhesion to the adsorbent surface, often resulting in a large number of adsorption sites on the surface of traditional adsorbents being covered by bacteria or other microorganisms, leading to poor adsorption of heavy metals. This invention introduces a bactericidal agent, Bdellovibrio, which significantly reduces the adsorption of bacteria and other microorganisms on the adsorbent surface, thereby improving the adsorption and removal effect of heavy metal ions. Furthermore, this invention improves and optimizes the preparation method of traditional bentonite-based adsorbents by introducing fulvic acid groups onto the bentonite surface and simultaneously modifying it with glyphosate grafting, thereby improving the adsorption and chelation of heavy metal ions by the adsorbent, macroscopically manifested as an improvement in the removal rate of heavy metal ions in wastewater.

[0058] Table 1

[0059] experimental group Copper ion removal rate Example 1 94.6％ Example 2 95.5％ Example 3 96.1％ Example 4 96.3％ Comparative Example 1 87.0％ Comparative Example 2 81.9％ Blank control group 72.4％

[0060] The technical solutions provided by the present invention have been described in detail above. For those skilled in the art, there will be changes in specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for combined microbial treatment of heavy metal wastewater, characterized in that, The treatment of heavy metal wastewater employs a microbial treatment agent, which includes a microbial preparation and an adsorbent, wherein the microbial preparation is a Bdellovibrio agent; and the adsorbent is bentonite-based adsorbent particles; the treatment steps include: (1) Inoculate the Bdellovibrio bacterial suspension and Escherichia coli bacterial suspension onto LB medium and culture at 32±2℃ for 50-100h. After culture, pick a single spot and immerse it in sterile water, centrifuge, and then inoculate it into agar medium for continuous subculturing for 3-5 generations to activate it. When phage plaques appear, pick the phage plaques into sterile water, centrifuge to separate them, and take the supernatant to remove Escherichia coli with a bacterial filter to obtain Bdellovibrio agent; (2) Prepare an aqueous solution of sodium carbonate and an aqueous solution of fulvic acid; add bentonite to the aqueous solution of sodium carbonate under stirring; after the addition is completed, heat the solution in a water bath to 60±5℃ and stir for more than 30 minutes; after stirring, separate the solid and liquid phases; wash the solid phase with deionized water more than 3 times and dry it to obtain a pretreated powder; add the pretreated powder to the aqueous solution of fulvic acid; after the addition is completed, stir for more than 30 minutes; then add hexadecyltrimethylammonium bromide to the solution under stirring; after the addition is completed, continue stirring for more than 5 hours; then separate the solid and liquid phases; wash the solid phase with deionized water more than 3 times and dry it to obtain fulvic acid modified particles; (3) Add the fulvic acid modified particles to deionized water and stir under ultrasonic conditions for more than 20 minutes to obtain a suspension; stir the suspension and then add glyphosate to the suspension while stirring. After the addition is completed, adjust the pH of the suspension to 10-11 with sodium hydroxide solution and then stir for more than 8 hours; after stirring, separate the solid and liquid phases, wash the solid phase with deionized water more than 3 times, and dry it to obtain bentonite-based adsorption particles. (4) Add the Bdellovibrio agent to the wastewater, heat it to 35±3℃ and stir for more than 20 minutes, then add the bentonite-based adsorbent particles while stirring. After the addition is completed, continue stirring at 35±3℃ for 1 to 2 hours to complete the treatment of heavy metal wastewater.

2. The method for combined microbial treatment of heavy metal wastewater according to claim 1, characterized in that, In step (1), the LB medium contains 0.5% peptone, 0.15% yeast extract, 0.25% sodium chloride, 0.4% agar, and the remainder is sterile distilled water.

3. The method for combined microbial treatment of heavy metal wastewater according to claim 1, characterized in that, In step (2), the concentration of sodium carbonate in the aqueous solution is 2-3 g / 100 mL, and the solvent is water; the concentration of fulvic acid in the aqueous solution is 0.8-1.4 g / 100 mL, and the solvent is water; the mass ratio of bentonite added to the aqueous solution of sodium carbonate is bentonite:sodium carbonate aqueous solution = 1:50-100; the mass ratio of pretreated powder added to the aqueous solution of fulvic acid is pretreated powder:fulvic acid aqueous solution = 1:100; the mass ratio of hexadecyltrimethylammonium bromide added to the mass ratio of the added pretreated powder is hexadecyltrimethylammonium bromide:pretreated powder = 3-4:

1.

4. The method for combined microbial treatment of heavy metal wastewater according to claim 1, characterized in that, In step (3), the mass ratio of the fulvic acid modified particles to deionized water is fulvic acid modified particles: deionized water = 1:1000; the mass ratio of the added glyphosate to the added fulvic acid modified particles is glyphosate: fulvic acid modified particles = 1~2:

1.

5. The method for combined microbial treatment of heavy metal wastewater according to claim 1, characterized in that, In step (3), the concentration of the solute in the sodium hydroxide solution is 1.5–2 mol / L, and the solvent is water.

6. The method for combined microbial treatment of heavy metal wastewater according to claim 1, characterized in that, In step (4), the mass ratio of the added Bdellovibrio agent and bentonite-based adsorption particles to the volume of the wastewater is Bdellovibrio agent: bentonite-based adsorption particles: wastewater = 2-2.5g: 0.2-0.3g: 500mL.