阅读说明：本技术 低成本的微生物絮凝剂制备方法及其在含铜重金属废水处理中的应用 (Preparation method of low-cost microbial flocculant and application of microbial flocculant in treatment of copper-containing heavy metal wastewater ) 是由 虞磊 华景秋 徐庆涛 何涛 张锐 于 2019-11-20 设计创作，主要内容包括：本发明公开了一种低成本的微生物絮凝剂制备方法,其步骤包括：将Bacillus菌种在盐水发酵培养基中培养；取盐水发酵培养基离心,得到上清液,上清液加NaCl进行沉淀,并收集沉淀；沉淀溶于纯水后透析,冷冻干燥,制得粉末状微生物絮凝剂。还公开了上述微生物絮凝剂在含铜重金属废水处理中的应用。本发明的有益效果：本发明的微生物絮凝剂无需在接种和扩大培养中进行高温灭菌处理,方法操作简单,可显著节省微生物絮凝剂的生产成本,生产的微生物絮凝剂对含铜的重金属废水能起到好的吸附去除作用。(The invention discloses a preparation method of a low-cost microbial flocculant, which comprises the following steps: culturing Bacillus strain in a saline fermentation culture medium; centrifuging a saline fermentation culture medium to obtain a supernatant, adding NaCl into the supernatant for precipitation, and collecting the precipitate; dissolving the precipitate in pure water, dialyzing, and freeze-drying to obtain powdered microbial flocculant. Also discloses application of the microbial flocculant in treatment of copper-containing heavy metal wastewater. The invention has the beneficial effects that: the microbial flocculant provided by the invention does not need high-temperature sterilization treatment in inoculation and amplification culture, the method is simple to operate, the production cost of the microbial flocculant can be obviously saved, and the produced microbial flocculant can well adsorb and remove copper-containing heavy metal wastewater.)

1. A low-cost preparation method of a microbial flocculant comprises the following steps:

(1) inoculating Bacillus sp strain into a seed culture medium, and culturing to obtain a seed solution;

(2) inoculating the seed liquid into a saline fermentation culture medium for culturing for 58-120 h;

(3) adjusting pH of a saline fermentation medium to be alkaline, performing ultrasonic treatment and centrifugation, collecting supernatant, adding saturated NaCl solution into the supernatant, and collecting precipitate;

(4) dissolving the precipitate in pure water, dialyzing, and freeze-drying to obtain powdered microbial flocculant;

wherein the concentration of sodium chloride in the saline fermentation medium is 50-150g/L, the Bacillus sp.

2. The method of claim 1 for preparing a low cost microbial flocculant, wherein the method comprises the steps of: the pH value of the saline fermentation medium is 7, and the mixture ratio is as follows: 10-20g/L of sucrose, 2g/L of yeast extract, 1g/L of urea, 2g/L of monopotassium phosphate, 2g/L of dipotassium phosphate, 50-150g/L of sodium chloride, 0.2g/L of magnesium sulfate heptahydrate and 1% V/V of SL-6 trace element solution.

3. The method of claim 2 for the preparation of a low cost microbial flocculant, wherein: the seed culture medium comprises the following components in percentage by weight: 10g/L of glucose, 1g/L of yeast extract, 1g/L of urea, 2g/L of monopotassium phosphate, 50-150g/L of sodium chloride, 0.2g/L of magnesium sulfate heptahydrate and SL-61%.

4. A low cost microbial flocculant preparation method according to claim 1, 2 or 3, characterized in that: and (3) adding a saturated NaCl solution into the supernatant in the step (2), stirring, standing for more than 8 hours, and then centrifuging to collect precipitates.

5. The method of claim 4 for preparing a low cost microbial flocculant, wherein the method comprises the steps of: in the step (3), a semi-permeable membrane with a molecular weight of 14kD is used for dialysis, and the dialysis time is more than 24 hours.

6. A microbial flocculant produced by the low-cost microbial flocculant preparation method of any one of claims 1 to 5.

7. The use of a microbial flocculant according to claim 6 in the treatment of copper-containing heavy metal wastewater, wherein the concentration of copper ions in the wastewater is in the range of 20 to 60 mg/L.

8. The use of claim 7, comprising the steps of: adding a microbial flocculant into copper-containing heavy metal wastewater, and stirring for treatment at the temperature of 4-45 ℃.

Technical Field

The invention relates to a preparation method of a low-cost microbial flocculant and application of the microbial flocculant in treatment of copper-containing heavy metal wastewater, belonging to the technical field of industrial wastewater treatment.

Background

As a waste water pretreatment medicament used earlier, chemical flocculants mainly comprise inorganic flocculants and organic polymeric flocculants, and the effect of flocculating the waste water by jointly adding the inorganic flocculants and the organic flocculants is obvious, but the chemical flocculants are not easy to degrade in the environment, have large residues, are easy to cause secondary pollution to the environment, have neurotoxicity and seriously threaten the health of human bodies. Meanwhile, the filter cloth of the plate-and-frame filter press is blocked due to the large use of the chemical flocculant in the sludge dewatering, and the subsequent treatment cost is increased due to the fact that the filter cloth is not easy to clean and treat. Compared with the chemical flocculating agent on the market, the microbial flocculating agent is a biological high molecular organic matter secreted to the outside of the body in the microbial growth process, and the main components are polysaccharide and protein. The flocculant can be automatically degraded in natural environment, has no residue and no secondary pollution, and is a novel environment-friendly flocculant.

In recent years, research on microbial flocculants has focused mainly on the optimization and application of culture conditions; for example, paracillin et al in patent CN110129375A improve the flocculation of microbial flocculants by optimizing the fermentation time and the extraction method of the flocculant; for example, patent CN108793426A issued to waiter et al discloses the application of a microbial flocculant mixture in combination with a natural polymer modified flocculant in the treatment of industrial and municipal wastewater; the cost control aspect is rarely reported, and the method can effectively block other strains in an inoculation link according to the strain performance, avoid the sterilization process of a seed culture medium and an expanded culture medium, and save energy loss generated by using steam, high pressure and the like, so the method has an obvious effect on the cost control aspect; meanwhile, the microbial flocculant cultured by the method has rich surface functional groups and has good purification effect on inorganic and organic pollutants such as heavy metals, dyes and the like in water.

Disclosure of Invention

In order to overcome the defects of the prior production technology, the invention provides a preparation method of a microbial flocculant.

The technical scheme adopted by the invention is as follows: the preparation method of the low-cost microbial flocculant comprises the following steps:

(1) inoculating Bacillus sp strain into a seed culture medium, and culturing to obtain a seed solution;

(2) inoculating the seed liquid into a saline fermentation culture medium for culturing for 58-120 h;

(3) adjusting pH of a saline fermentation medium to be alkaline, performing ultrasonic treatment and centrifugation, collecting supernatant, adding saturated NaCl solution into the supernatant, and collecting precipitate;

(4) dissolving the precipitate in pure water, dialyzing, and freeze-drying to obtain powdered microbial flocculant;

wherein, the concentration of sodium chloride in the saline fermentation medium is 50-150g/L, the bacterial colony of Bacillus sp. Year 2015, 2 months and 11 days. Address of the depository: no. 6 building of No. 24 Hotel Xianqiao west way in the rising area of Beijing.

The seed culture medium in the step (1): 10g/L of glucose, 1g/L of yeast extract, 1g/L of urea, 2g/L of monopotassium phosphate, 50-150g/L of sodium chloride, 0.2g/L of heptahydrate and magnesium sulfate and SL-61% (V/V).

The saline fermentation medium in the step (2) comprises 20g/L of sucrose, 2g/L of yeast extract, 1g/L of urea, 2g/L of monopotassium phosphate, 2g/L of dipotassium phosphate, 50-150g/L of sodium chloride, 0.2g/L of heptahydrate and magnesium sulfate and SL-61% (V/V).

And (3) adding a saturated NaCl solution into the supernatant in the step (2), stirring, standing for more than 8 hours, and then centrifuging to collect precipitates.

In the step (3), a semi-permeable membrane with the molecular weight of 14kD is used for dialysis, and the dialysis time is more than 24 hours.

The invention also discloses the microbial flocculant prepared by the low-cost microbial flocculant preparation method.

And the application of the microbial flocculant in the treatment of copper-containing heavy metal wastewater, wherein the concentration range of heavy metal in the wastewater is 20-60 mg/L.

The application steps include: adding a microbial flocculant into copper-containing heavy metal wastewater, and stirring for treatment at the temperature of 4-45 ℃.

The invention has the beneficial effects that: by utilizing the characteristic that the Bacillus sp strain can grow under the high salt concentration of more than 5 percent, the sterilization process in the two processes is reduced and the production cost is saved by adjusting the sodium chloride concentration in the seed culture medium and the fermentation culture medium to be more than 5 percent in the process of producing the flocculant. The method has the advantages that the yield of the flocculant is high, and 1g of the flocculant is produced in 1L of culture medium. The microbial flocculant produced by the invention has good flocculation effect and wide application range, and has the flocculation rate of more than 90 percent on kaolin suspension under the condition that the pH value is 2-10. The microbial flocculant contains 54.95% of polysaccharide and 21.53% of protein, and plays a main role in the flocculation process, the polysaccharide component has the flocculation effect of being maintained at about 90% after being treated at the high temperature of 100 ℃ for 10 minutes. The microbial flocculant cultured by the method has rich surface functional groups, has good adsorption effect on heavy metals in water, and can be used for treating high-concentration Cu of 20-60mg/L by using 100mg/L flocculant²⁺The removal rate is more than 35%.

Drawings

FIG. 1 is a graph showing the growth of Bacillus bacteria at different salt concentrations.

The right part of the graph 2 is a comparison graph of the flocculation effect of adding 0.3ml of 0.1mol/L ferric chloride solution, 0.3ml of 0.1mol/L ferric chloride solution and 0.6mg of flocculant and adding 0.6mg of flocculant to 50ml of 3g/L kaolin suspension respectively.

FIG. 3 is an SEM image of a flocculating agent and an electron energy loss spectrum mapping image of the flocculating agent after copper ions are adsorbed by the flocculating agent.

FIG. 4 is a graph showing sequencing results of a bacterial liquid cultured in a saline fermentation medium having a salt concentration of 50 g/L.

FIG. 5 is a diagram showing the alignment of the sequencing sequence Blast of the bacterial liquid cultured in the saline fermentation medium with 50g/L salt concentration.

FIG. 6 is a graph showing the effect of the composition and components of the flocculant on flocculation.

Detailed Description