Biological treatment agent for mine heavy metal wastewater and preparation method of biological treatment agent

Abstract

The invention discloses a biological treatment agent for mine heavy metal wastewater and a preparation method of the biological treatment agent, and relates to the technical field of heavy metal wastewater treatment.The biological treatment agent is prepared by the steps that firstly, marine rhodotorula benthica and rhizopus nigricans are cultured through a liquid culture medium to obtain mixed bacterium suspension, and then the mixed bacterium suspension is adsorbed through modified coal gangue; and then carrying out sodium alginate-polyvinyl alcohol composite embedding and immobilization to obtain the product. The modified coal gangue serves as an adsorption carrier and is combined with sodium alginate and polyvinyl alcohol to prepare the composite immobilized microbial agent capable of stably exerting microbial activity, multiple heavy metals can be efficiently purified at the same time, meanwhile, COD and chromaticity in wastewater can be synchronously reduced, the comprehensive treatment effect is excellent, and the method is suitable for industrial production. The application prospect is good.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy metal wastewater treatment, and in particular relates to a biological treatment agent for mine heavy metal wastewater and a preparation method thereof. Background Art

[0002] Nonferrous metal mining and smelting operations in mines will result in the generation of heavy metal-contaminated wastewater. The content of arsenic and manganese in heavy metal-contaminated wastewater is relatively high. Discharging it into natural water bodies will cause harm to human health and the ecological environment. Therefore, scientific treatment methods are needed to achieve standard discharge and emission reduction of heavy metals in wastewater.

[0003] At present, the traditional treatment processes for heavy metal wastewater mainly include adsorption, chemical precipitation, ion exchange and electrolysis. The adsorption method uses adsorbents with high specific surface area or special functional groups to remove heavy metal ions in wastewater through physical or chemical adsorption. Adsorbents have strong adsorption capacity for a variety of metal ions. Traditional adsorbents mainly include activated carbon and clay minerals. The chemical precipitation method removes heavy metal ions by adding chemical reagents to react with wastewater to produce precipitation. The ion exchange method reduces the concentration of heavy metal ions by contacting the active groups on the ion exchange resin with the heavy metal ions in the wastewater to produce a reversible ion exchange reaction. The electrolysis method is that under the action of a DC electric field, the charged heavy metal ions in the wastewater migrate to the cathode and are reduced in the cathode. The generated metal elements are precipitated or adsorbed on the surface of the electrode to achieve the removal and recovery of heavy metals in the wastewater.

[0004] The above traditional processes for heavy metal contaminated wastewater have various defects and deficiencies, such as high operating costs, high energy consumption, and easy secondary pollution. At present, biological treatment methods can make up for the above deficiencies. Biological agents complex with heavy metals in wastewater to form stable heavy metal complexes. Since biological agents also have the function of efficient flocculants, when heavy metal complexes are hydrolyzed to form particles, they can quickly flocculate to form micelles, achieving efficient purification of multiple heavy metals at the same time.

[0005] As for biological treatment methods, there is currently a technical problem that biological agents are easily destroyed in wastewater environments, reducing the activity of microorganisms, and making it difficult to comprehensively improve the treatment effect. To this end, the present invention provides a new biological treatment agent for mine heavy metal wastewater and a preparation method thereof. Summary of the invention

[0006] The purpose of the present invention is to provide a biological treatment agent for mine heavy metal wastewater and a preparation method thereof in order to solve the above problems.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0008] As a first aspect of the present invention, the present invention provides a biological treatment agent for heavy metal wastewater in mines. The biological treatment agent is prepared by first culturing marine red yeast and black root mold in a liquid culture medium to obtain a mixed bacterial suspension, then adsorbing the mixed bacterial suspension on modified coal gangue, and then fixing it with a sodium alginate-polyvinyl alcohol composite encapsulation.

[0009] As a further optimization scheme of the present invention, the total inoculation amount of the marine red yeast and black root mold is 10-20% of the volume of the liquid culture medium, and the inoculation volume ratio of the marine red yeast to black root mold is (1-3):1.

[0010] As a further optimization scheme of the present invention, the added amount of the modified coal gangue is 5-10 g of modified coal gangue per 100 mL of the mixed bacterial suspension.

[0011] As a further optimization scheme of the present invention, the modified coal gangue is obtained by mixing coal gangue with a mixed solution of humic acid and ascorbic acid and shaking for 2-3 hours, and then naturally drying.

[0012] As a further optimization scheme of the present invention, the volume ratio of the coal gangue to the mixed solution of humic acid and ascorbic acid is 1:(2-6), and the mass ratio of humic acid to ascorbic acid is (4-6):1.

[0013] As a second aspect of the present invention, the present invention also provides a method for preparing a biological treatment agent for heavy metal wastewater in mines as described above, comprising the following steps:

[0014] (1) First, inoculate marine red yeast and black root mold into the liquid culture medium and mix them evenly. Then, culture the inoculated liquid culture medium at 20-30°C until the total number of viable bacteria in the liquid culture medium is not less than 5×10 8 CFU / mL, after washing with NaCl aqueous solution, the NaCl aqueous solution was added again to obtain a mixed bacterial suspension;

[0015] (2) First, the marine red yeast and black root mold in the mixed bacterial suspension are adsorbed by modified coal gangue to obtain a coal gangue-mixed bacterial suspension, and then a mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol is added to the coal gangue-mixed bacterial suspension, and after uniform mixing, a coal gangue composite bacterial mixed liquid is obtained, and the coal gangue composite bacterial mixed liquid is added to a calcium chloride solution for cross-linking, and then washed and dried.

[0016] As a further optimization scheme of the present invention, the volume ratio of the mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol to the coal gangue-mixed bacteria suspension is (1-2):1.

[0017] The beneficial effects of the present invention are:

[0018] The biological treatment agent provided by the present invention is prepared by first culturing marine red yeast and black root mold in a liquid culture medium to obtain a mixed bacterial suspension, then first adsorbing the mixed bacterial suspension on modified coal gangue, and then fixing it by sodium alginate-polyvinyl alcohol composite encapsulation. The present invention uses modified coal gangue as an adsorption carrier and combines it with sodium alginate and polyvinyl alcohol to prepare a composite immobilized bacterial agent that can stably exert microbial activity. It can achieve efficient purification of multiple heavy metals at the same time and can also simultaneously reduce COD (chemical oxygen demand) and chromaticity in wastewater, has excellent comprehensive treatment effect, and has good application prospects. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Technicians in this field can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0020] 1. Materials and Methods

[0021] The methods used in this example are conventional methods known to those skilled in the art unless otherwise specified, and the reagents and other materials used are commercially available products unless otherwise specified.

[0022] Marine red yeast (Rhodotorula sp.), from Shandong Yihao Biotechnology;

[0023] Rhizopus stolonifer, from Shanghai Institute of Microbiology;

[0024] Rhodotorula mucilaginosa, from Testo Biotechnology;

[0025] The liquid culture medium is a commercially available LB liquid culture medium, which is prepared by adding 10 g of trypsin, 5 g of yeast extract, and 10 g of NaCl to 950 ml of deionized water, shaking the container until the solute is dissolved, then adjusting the pH to 7.0 with 5 mol / L NaOH, and finally making up to 1 L with deionized water and sterilizing.

[0026] 2. Verification Test

[0027] 1. Preparation of biological treatment agents

[0028] 1.1. Preparation of mixed bacterial suspension

[0029] Inoculate the marine red yeast and black root mold into the prepared LB liquid culture medium and mix well. Cultivate the inoculated liquid culture medium at 20-30°C until the total number of viable bacteria in the liquid culture medium is not less than 5×108 CFU / mL, after washing with NaCl aqueous solution, re-adding NaCl aqueous solution can obtain a mixed bacterial suspension, the total inoculation amount of marine red yeast and black root mold is 10-20% of the volume of the liquid culture medium, and the inoculation volume ratio of the marine red yeast and black root mold is (3-1):1. In this embodiment, the total inoculation amount of marine red yeast and black root mold is preferably 20% of the volume of the liquid culture medium, and the inoculation volume ratio of the two is preferably 1:1 for subsequent effect verification.

[0030] 1.2. Immobilization treatment of mixed bacterial suspension

[0031] (1) Preparation of modified coal gangue

[0032] The gangue and the mixed solution of humic acid and ascorbic acid were mixed and shaken for 2 hours, and then naturally dried at 25° C. to obtain modified gangue. In this embodiment, the volume ratio of the gangue to the mixed solution of humic acid and ascorbic acid is preferably 1:5, and the mass ratio of humic acid to ascorbic acid is preferably 4:1.

[0033] (2) Preparation of mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol

[0034] Sodium alginate and polyvinyl alcohol are uniformly dissolved in a NaCl aqueous solution, and sterilized at 121° C. for 20 minutes to obtain a mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol. The mass concentration of the NaCl aqueous solution is 0.9% based on the total weight of distilled water used to prepare the NaCl aqueous solution. The sum of the masses of the NaCl aqueous solution used to prepare the mixed bacterial suspension and the NaCl aqueous solution used to prepare the mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol is 100%, the mass concentration of sodium alginate is 1-5%, and the mass concentration of polyvinyl alcohol is 1-3%. In this embodiment, the mass concentration of sodium alginate is preferably 5%, and the mass concentration of polyvinyl alcohol is preferably 3%.

[0035] (3) Immobilization treatment

[0036] First, the mixed bacterial suspension is adsorbed by modified coal gangue to obtain a coal gangue-mixed bacterial suspension. The amount of modified coal gangue added is 5-10 g per 100 mL of mixed bacterial suspension. In this embodiment, it is preferred to add 10 g per 100 mL of mixed bacterial suspension for subsequent effect verification.

[0037] Then, a mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol is added to the gangue-mixed bacterial suspension, and the mixture is evenly mixed to obtain a gangue composite bacterial mixture. The gangue composite bacterial mixture is added to a calcium chloride solution for cross-linking, and then washed and dried. The mass sum of the NaCl aqueous solution used to prepare the mixed bacterial suspension and the NaCl aqueous solution used to prepare the NaCl aqueous solution of sodium alginate and polyvinyl alcohol is 100%, and the mass concentration of the calcium chloride solution is 2%-4%. In this embodiment, the mass concentration of the calcium chloride solution is preferably 2%.

[0038] 1.3. Composition design of biological treatment agent

[0039] (1) In order to explore the effect of the composition of the mixed bacterial suspension in the biological treatment agent on the treatment effect of mine heavy metal wastewater, the bacterial composition of the mixed bacterial suspension was designed as follows:

[0040] Mixed bacterial suspension A: The bacterial species consist of marine red yeast and black root mold;

[0041] Mixed bacterial suspension B: The bacterial species are red yeast and black root mold;

[0042] Mixed bacterial suspension C: The bacterial species consisted only of marine red yeast;

[0043] Mixed bacterial suspension D: The bacterial species consisted only of Rhizopus nigrofusus;

[0044] Then, biotreatment agent A, biotreatment agent B, biotreatment agent C and biotreatment agent D are prepared according to the preparation method of the biotreatment agent disclosed in steps 1.1-1.2.

[0045] (2) To explore the effect of modified coal gangue in biological treatment agents on the treatment of heavy metal wastewater in mines

[0046] The mixed bacterial suspension A was adsorbed by unmodified coal gangue, activated carbon was used instead of coal gangue, and the modified activated carbon obtained by the same modification method was adsorbed by the mixed bacterial suspension A, and then biological treatment agents E and F were prepared according to step 1.2.

[0047] (3) To explore the effect of immobilized biological treatment agents on the treatment of heavy metal wastewater in mines

[0048] The mixed bacterial suspension A without immobilization treatment was used as the biological treatment agent G;

[0049] The mixed liquor of composite bacteria of coal gangue obtained only by adsorption treatment of modified coal gangue was used as biological treatment agent H.

[0050] 2. Biological agent method for treating mine wastewater

[0051] After the sampled ore dressing wastewater was regulated in the regulating tank for water quality and water quantity, it was divided into 8 treatment groups according to the same treatment volume, and added to the matching reaction tank and treated with the same amount of biological treatment agent AH (added at 0.5L / cm 3 , solid concentration is about 30%, density is 1.3kg / L) and then fully mixed into the hydrolysis reaction tank. Under the action of the aerator, lime milk and biological agents are added to the wastewater and fully mixed and hydrolyzed. Finally, it flows into the flocculation reaction tank, and large flocs are generated under the action of the coagulant polyacrylamids (PAM). The wastewater after the reaction enters the sedimentation tank for solid-liquid separation. The supernatant of the sedimentation tank is neutralized and adjusted in the clear water tank with sulfuric acid before being tested. The sedimentation tank sludge is pumped into the sludge thickening tank for further dehydration, and the thickening tank sludge is pumped into the filter press to generate filter cake, which is safely disposed of.

[0052] The typical water quality analysis of the sampled mineral processing wastewater before treatment is shown in Table 1.

[0053] Table 1 Typical water quality analysis of sampled mineral processing wastewater before treatment (unit: mg / L)

[0054]

[0055] 3. Water quality testing and analysis

[0056] (1) Detection of heavy metal content

[0057] Total arsenic (TAs) was detected by silver diethyldithiocarbamate spectrophotometry (GB7485-87), total manganese (TMn) was detected by flame atomic absorption spectrophotometry (GB11911-89), total chromium (TCr) was detected by potassium permanganate oxidation-diphenylcarbazide spectrophotometry (GB7466-87), and total zinc (TZn), total lead (TPb), total cadmium (TCd), etc. were detected by atomic absorption spectrophotometry (GB7475-87).

[0058] (2) Detection of total heavy metal removal rate

[0059] The calculation is based on the total heavy metal content before and after treatment, and the calculation formula is as follows:

[0060]

[0061] The results of heavy metal removal effects are shown in Table 2.

[0062] Table 2 Statistical table of heavy metal removal effects (unit: mg / L)

[0063]

[0064]

[0065] From Table 2 we can see that:

[0066] Compared with the use of biological treatment agent AD to treat mineral processing wastewater, biological treatment agent A has the best effect in removing heavy metals, with the highest total heavy metal removal rate of 94.13%. The effect of biological treatment agent B in removing heavy metals is not significantly different from that of biological treatment agent A, and its total heavy metal removal rate is 92.44%. Biological treatment agent CD uses single strains of marine red yeast and black root mold respectively, but the removal effect is not as good as the combination of the two, especially for the removal of total metal arsenic. The combination of marine red yeast and black root mold has a synergistic effect and can significantly reduce the total heavy metal arsenic content in wastewater.

[0067] Comparing the use of biological treatment agent A and biological treatment agent EF to treat mineral processing wastewater, the effect of biological treatment agent F in removing total heavy metals is the same as that of biological treatment agent A. It can be seen that the effect of activated carbon fixed mixed bacteria suspension and modified coal gangue fixed mixed bacteria suspension treated by the same modification method is equivalent.

[0068] Comparing the use of biological treatment agent A and biological treatment agent GH to treat mineral processing wastewater, biological treatment agent G has the worst effect in removing total heavy metals. It can be seen that the biological treatment agent that has not been immobilized is easily disturbed and damaged by the external environment during the treatment of mineral processing wastewater, resulting in reduced adsorption and degradation performance of heavy metals. After immobilization treatment, it can help microorganisms resist interference from the external environment, enhance microbial activity and degradation-related enzyme activity, and improve the competitiveness of biological treatment agents in wastewater environments, thereby improving the performance of adsorption and degradation of heavy metals.

[0069] (2) COD and color detection

[0070] COD was tested using the potassium dichromate method (GB11914-89), and chromaticity was tested using the dilution multiple method (GB11903-89). The test results are shown in Table 3.

[0071] Table 3 Statistical table of COD and chromaticity test results (unit: mg / L)

[0072]

[0073]

[0074] From Table 3 we can see that:

[0075] Comparing the use of biological treatment agent AD to treat mineral processing wastewater, biological treatment agent A has the best effect on reducing COD and chromaticity of mineral processing wastewater, while biological treatment agent B has the worst effect among biological treatment agents AD. It can be seen that marine red yeast is better than gum red yeast in reducing COD and chromaticity of mineral processing wastewater. In terms of reducing COD and chromaticity of mineral processing wastewater, the combination of marine red yeast and black root mold has a synergistic effect.

[0076] By comparing the use of biological treatment agent A and biological treatment agent EF to treat mineral processing wastewater, it can be seen that the modified coal gangue is better than modified activated carbon in reducing the COD and chromaticity of mineral processing wastewater, and the modified coal gangue is better than the unmodified coal gangue in reducing the COD and chromaticity of mineral processing wastewater.

[0077] By comparing the treatment of mineral processing wastewater with biological treatment agent A and biological treatment agent GH, it can be seen that the treatment of mineral processing wastewater with biological treatment agent that has not been immobilized is also not conducive to the reduction of COD and chromaticity of mineral processing wastewater.

[0078] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A biological treatment agent for heavy metal wastewater in mines, characterized in that: The biological treatment agent is obtained by first culturing marine red yeast and black root mold in a liquid culture medium to obtain a mixed bacterial suspension, then adsorbing the mixed bacterial suspension on modified coal gangue, and then embedding and fixing it with sodium alginate-polyvinyl alcohol composite.

2. A biological treatment agent for heavy metal wastewater in mines according to claim 1, characterized in that: The total inoculation amount of the marine red yeast and the black root mold is 10-20% of the volume of the liquid culture medium, and the inoculation volume ratio of the marine red yeast to the black root mold is (1-3):

1.

3. A biological treatment agent for heavy metal wastewater in mines according to claim 1, characterized in that: The modified coal gangue is added in an amount of 5-10 g of modified coal gangue per 100 mL of the mixed bacterial suspension.

4. A biological treatment agent for heavy metal wastewater in mines according to claim 1, characterized in that: The modified coal gangue is obtained by mixing coal gangue with a mixed solution of humic acid and ascorbic acid, shaking for 2-3 hours, and then naturally drying.

5. A biological treatment agent for heavy metal wastewater in mines according to claim 4, characterized in that: The volume ratio of the coal gangue to the mixed solution of humic acid and ascorbic acid is 1:(2-6), and the mass ratio of humic acid to ascorbic acid is (4-6):

1.

6. A method for preparing a biological treatment agent for mine heavy metal wastewater according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) First, inoculate marine red yeast and black root mold into the liquid culture medium and mix them evenly. Then, culture the inoculated liquid culture medium at 20-30°C until the total number of viable bacteria in the liquid culture medium is not less than 5×10 8 CFU / mL, after washing with NaCl aqueous solution, the NaCl aqueous solution was added again to obtain a mixed bacterial suspension; (2) First, the marine red yeast and black root mold in the mixed bacterial suspension are adsorbed by modified coal gangue to obtain a coal gangue-mixed bacterial suspension, and then a mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol is added to the coal gangue-mixed bacterial suspension, and after uniform mixing, a coal gangue composite bacterial mixed liquid is obtained, and the coal gangue composite bacterial mixed liquid is added to a calcium chloride solution for cross-linking, and then washed and dried.

7. The method for preparing a biological treatment agent for heavy metal wastewater in mines according to claim 6, characterized in that: The volume ratio of the mixed NaCl aqueous solution of sodium alginate and polyvinyl alcohol to the coal gangue-mixed bacteria suspension is (1-2):1.

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