LU502897B1

LU502897B1 - Slow-release compound flocculant for reducing acidity of mine water

Info

Publication number: LU502897B1
Application number: LU502897A
Authority: LU
Inventors: Jinjing Lu
Original assignee: The College Of Resources And Environment Shanxi Agricultural Univ; Institute Of Eco Environment And Industrial Technology Shanxi Agricultural Univ
Priority date: 2022-10-13
Filing date: 2022-10-13
Publication date: 2023-04-18

Abstract

The invention provides a slow-release compound flocculant for reducing the acidity of mine water, consisting of 87-95wt% of inorganic compound flocculant and 5-13wt% of soluble coating on the inorganic compound flocculant, wherein the inorganic compound flocculant consists of microbial carbon source, coagulant aid and adsorbent; the soluble coating is a culture medium mixed with microbial inoculum, wherein the microbial inoculum is a mixed inoculum composed of Desulfovibrio, colourless sulphur bacteria and Gluconobacter. According to the invention, the characteristics of inorganic and biological flocculants are integrated, the dosing mode of the medicament is improved, and the multi-step dissolution and slow release process increases the action efficiency of various flocculants and improves the medicament efficiency.

Description

SLOW-RELEASE COMPOUND FLOCCULANT FOR REDUCING 17008807

ACIDITY OF MINE WATER

TECHNICAL FIELD

The invention relates to a water treatment agent, in particular to a flocculant for acid mine water treatment.

BACKGROUND

The mine water whose pH value is less than 5.5 is called acid mine water, which is the main water pollutant produced in the process of coal mining and one of the factors that cause the deterioration of water ecological environment in mining area.

Oxidation of coal sulphide and ferrous ion are the main causes of mine water turning sour.

At present, the main treatment methods of acid mine water include neutralization, constructed wetland, sulphide precipitation and microbial method. Neutralization method neutralizes hydrogen ions in wastewater by adding limestone or lime, which has the disadvantages of high cost and more calcium sulphate residues generated by the reaction, which is easy to cause secondary pollution. Constructed wetland method uses plants and soil in wetland system to adsorb and filter metal ions in acid wastewater. This method is simple to operate and easy to manage, but it covers a large area, the treatment process is easily affected by the environment, and the residual H2S after treatment will cause air pollution. Sulphide precipitation method selectively precipitates metal ions in waste water by adding sulphide, which has some problems, such as high treatment cost, and environmental pollution under aerobic conditions.

Microbial method uses sulphate reducing bacteria (SRB) to reduce sulphate in acid mine water into sulphide under anaerobic conditions, and the generated sulphide reacts with heavy metals in wastewater to generate insoluble metal sulphide. The desulfurization and iron removal of mine water by microbial method has the characteristics of mild reaction conditions, low cost, low energy consumption, and no secondary pollution, so it has been widely concerned.

Flocculation process is an indispensable key link in wastewater treatment at 502897 home and abroad. The quality of flocculation effect determines the operation status of the follow-up process, the final effluent quality and treatment cost, and the choice of flocculant has important technical and economic value for improving the water quality of Takaizumi and reducing the cost of water production. At present, the widely used chemical flocculants show certain ecological insecurity in the process of production and use, and cause secondary pollution to the environment. Therefore, the domestic and foreign eyes are gradually turning to the biological field.

Microbial flocculant (MBF) is a kind of metabolic product produced by microorganisms and secreted out of cells, which has flocculation activity. It is an efficient, nontoxic and inexpensive water treatment agent with biodegradability and safety.

The research on microbial flocculants abroad has been extensive, while the domestic research is still in the stage of strain screening, which mainly has some disadvantages, such as high cost, single treatment function, difficult activity preservation and difficult industrialization. In view of the limitations of microbial flocculants, the development of low-cost and high-efficiency Compound bioflocculant (CBF) with various components has become a new research direction of microbial flocculants. This kind of microbial flocculants can complement each other's advantages and enhance their efficiency.

CN101671074A discloses a neutralizer for acid mine water treatment in

Zhaotong area and its preparation method. It takes Permian Maokou dolomitic limestone in Zhaotong area, Yunnan province as the main component of mine water treatment, which is easy to obtain, but it does not integrate other microbial methods with higher environmental protection. CN101935621B discloses a genetic engineering bacterium of Thiobacillusferrooxidans and its application. CYC] gene of the electron transfer chain protein of Thiobacillusferrooxidans is introduced into

Thiobacillusferrooxidans by transgenic method to improve its ability to oxidize Fe” ions, and its application in treating acidic mine water is mentioned. However, its function is relatively simple, and it does not cooperate with other inorganic methods to treat mine water synchronously. CN103466842A discloses an acid mine water 17008807 treatment method, which uses a three-stage treatment device with a drop to treat mine water. Cheap materials such as fly ash and fruit shells are used as filter materials, which can effectively solve the acid mine water pollution problem in mining areas.

However, the investment cost of this method is large and the operation steps are relatively cumbersome. At present, limestone flocculant is widely used to treat acid mine water, but the flocs of ferric hydroxide and ferrous hydroxide produced in the treatment process are coated on the surface of lime particles, which greatly reduces the neutralization efficiency. The pH value of the treated mine water is difficult to meet the national discharge requirements, and the removal effect of iron is low, and there are more precipitates, which is easy to cause secondary pollution.

SUMMARY

The purpose of the invention is to provide a slow-release compound flocculant for reducing the acidity of mine water, which can improve the rate and efficiency of acid mine water treatment by microbial and inorganic compound flocculation.

The invention is to provide a slow-release compound flocculant for reducing the acidity of mine water, consisting of 87-95wt% of inorganic compound flocculant and 5-13wt% of soluble coating on the inorganic compound flocculant, wherein

The inorganic compound flocculant consists of 40-50 parts by mass of microbial carbon source, 20-35 parts by mass of coagulant aid and 3-10 parts by mass of adsorbent,

The soluble coating is a culture medium mixed with microbial inoculum, wherein the microbial inoculum is a mixed inoculum composed of Desulfovibrio, colourless sulphur bacteria and Gluconobacter, the total number of viable bacteria in each gram of coating is 6x10°-1x10! the ratio of viable bacteria among

Desulfovibrio, colourless sulphur bacteria and Gluconobacter is (1-1.5):(1-1.5):0.5, and the colourless sulphur bacteria is a mixed bacteria of Thiobacillusferrooxidans and Acidithiobacillus thiooxidans in the mass ratio of (0. 2-1):1.

In the inorganic compound flocculant, the microbial carbon source is one or a 17008807 mixture of several of fly ash, peat and glucose in any proportion.

The coagulant aid is a mixture of one or two of CaCl, and bone glue in any proportion.

The adsorbent is one or a mixture of several of activated carbon, zeolite, coal gangue and fruit shells in any proportion.

Further, a small amount of ferrous sulphate can also be added to the microbial carbon source. The addition of ferrous sulphate accounts for 0.04-0.2% of the total mass of microbial carbon source.

In the soluble coating of the invention, the culture medium is a mixed culture medium composed of one or more of starch, soluble cellulose and beef paste culture medium.

Preferably, the soluble coating of the present invention is composed of 7-10 parts by mass of culture medium and 0.8-3 parts by mass of microbial inoculum.

More preferably, the colourless sulphur bacteria described in the present invention is a mixed bacteria of Thiobacillusferrooxidans and Acidithiobacillus thiooxidans in the ratio of (0.2-1):1.

The slow-release compound flocculant prepared by the invention is spherical or nearly spherical particles with a particle size of 0.5-3.0 mm.

The slow-release compound flocculant of the invention can be prepared by coating inorganic compound flocculant with soluble coating by spraying compound, chemical crosslinking agent mixing, reagent coating and other methods.

The slow-release compound flocculant of the invention not only utilizes the desulfurization and Fe** removal effect of microbial method, but also combines the strong flocculation effect of inorganic compound flocculation and biological flocculation, so that the flocculation effect is developed to the greatest extent, and its action principle is as follows: when the slow-release compound flocculant enters the water body, the soluble coating on the surface layer is dissolved at first, and various microbial agents are advanced into the water body, and the microbial method is used for desulfurization and Fe?" removal. On the one hand, under the action of sulphate-reducing bacteria (Desulfovibrio), sulphate can be efficiently reduced to 502897 low-priced sulphide, that is, SO4’ is reduced to HS, and then thiooxidans in colourless sulphur bacteria oxidizes HS to elemental sulphur and removes it; on the other hand, the existence of Acidithiobacillus ferrooxidans can accelerate the 5 oxidation of Fe**, produce Fe**, and then hydrolyse to form Fe(OH); precipitate. Part of H,S can also form insoluble metal sulphide precipitate with Fe”, thus effectively removing acid-causing ions in mine water. Then the inorganic compound flocculant in the inner layer enters the water, and the microbial carbon source, inorganic coagulant aid and adsorbent are released. On the one hand, the carbon source maintains the metabolic needs of the aforementioned microorganisms. On the other hand, inorganic compound flocculants and metabolites of some microorganisms (Gluconobacter) can make the generated precipitate adsorb and flocculate, and separate from the water body; in addition, with the action of coagulant aid such as CaCl, and adsorbent, the generated precipitate can be quickly adsorbed. At the same time, with the continuous metabolism of microorganism Gluconobacter, the flocculation effect of its secretion on mine water is constantly strengthened. Combined with inorganic compound flocculant, the removal rate of suspended matter in mine water can reach more than 98%.

Therefore, the biological components and inorganic components in the slow-release compound flocculant act according to a certain sequence, thus giving full play to the working efficiency of various action processes.

The slow-release compound flocculant of the invention combines the characteristics of microbial method and inorganic compound flocculant, efficiently desulfurizes and removes iron from acidic mine water by microbial method, and simultaneously flocculates the generated sulphide precipitate and iron oxide precipitate by inorganic flocculation and biological flocculation, so as to reduce the acid-causing ions of mine water and achieve the purpose of reducing the acidity of mine water. The invention can not only give play to the characteristics of high environmental protection performance, mild reaction conditions, low cost and low energy consumption of microbial method, but also make use of the strong flocculation efficiency of biological and inorganic compound flocculants, overcome the 17008807 shortcomings of other general organic and inorganic chemical flocculants such as low floc strength, large dosage and much pollution, and greatly improve the speed and efficiency of mine water treatment.

The slow-release compound flocculant of the invention improves the action mode of the agents, and through slow-release treatment and step-by-step dissolution of flocculants with different components, each compound agent forms a circular action mode, i.e. precipitation-flocculation-adsorption, in the process of dissolution after dosing, which not only provides relatively independent action time of each agent, but also ensures the continuity of action time of each agent and the complementarity between effects and energy, so that each agent can give full play to its performance.

Through the process of multi-step dissolution and slow release, the action efficiency of various components is increased, and the efficacy of the medicament is improved.

The slow-release compound flocculant of the invention integrates the functions of sewage flocculation reaction, sedimentation, adsorption and the like, and the sequential action of the agents in time increases the overall efficiency of the compound agent, reduces the dosage, simplifies the dosing equipment, has simple and easy sewage treatment process, reduces the operation cost and reduces the secondary pollution.

DESCRIPTION OF THE INVENTION

Embodiment 1

Take 40 Kg peat, 10 Kg glucose, 30 Kg bone glue, 7 Kg activated carbon and 0.03 Kg ferrous sulphate, stir them evenly, add 20-28 L water, keep stirring for 20-30 min, granulate by disc or extrusion, and dry them to obtain inorganic compound flocculant with particle size of 0.2-2.5 mm;

Take 7.0 Kg of starch and 7.0 Kg of beef paste, add 1.0 Kg of Desulfovibrio, 1.0

Kg of colourless sulphur bacteria (including 0.4 Kg of Thiobacillusferrooxidans and 0.6 Kg of Acidithiobacillus thiooxidans) and 0.5 Kg of Gluconobacter, and mix them evenly (the number of viable bacteria of each agent is not less than 2x107-2x10%/g);

then add 30-40% of the total weight of sterile water, stir and ferment at 28-36°C for 502897 16-24 h to obtain bacterial liquid, where the total number of viable bacteria reaches 6x10°-1x10"//g;

Pour 14.5 Kg of the fermented mixed culture medium (water content 3.33 Kg) into 89 Kg of inorganic compound flocculant particles, fully stir for 1 h, and naturally cool and dry at room temperature to obtain slow-release compound flocculant particles with a particle size of 0.5-3.0 mm;

Take the mine wastewater discharged from a coal mine, and test it by conventional chemical analysis method, wherein the pH value is 3.0, the total Fe content is 250 mg/L, and the SO4” content is 760 mg/L, leave the wastewater in the regulating tank for 1 hour to balance the water quality and quantity, and preliminarily remove the larger suspended substances in the wastewater, such as coal dust, rock powder, clay and other fine particles, especially coal powder; after the wastewater with balanced water quality enters the coagulation tank, let it stand for 20 minutes, use the powder dosing device, add the slow-release compound flocculant particles of this embodiment at the dosage of 15 g/m’, and stir them mechanically; after settling in the inclined plate sedimentation tank, test the effluent water quality again; as a result, the pH value can be increased to 6.0 left and right, while the total Fe content is reduced to 10 mg/L and the SO4* content is reduced to less than 240 mg/L.

Embodiment 2

Take 35 Kg of fly ash, 15 Kg of glucose, 28 kg of CaCl,, 9 Kg of zeolite and 0 .05 Kg of ferrous sulphate, stir them evenly, add 20-28 L of water, stir for 20-30 min, granulate by disc or extrusion, and dry them to obtain the inorganic compound flocculant with particle size of 0.2-2.5 mm;

Take 5.0 Kg of starch, 2.0 Kg of soluble cellulose and 7.0 Kg of beef paste, add 1.0 Kg of Desulfovibrio, 1.0 Kg of colourless sulphur bacteria (including 0.5 Kg of thiobacillusferrooxidans and 0.5 Kg of Acidithiobacillus thiooxidans) and 0.6 Kg of

Gluconobacter, mix them evenly (the number of viable bacteria of each agent 1s not less than 2x107-2x10%), add 30-40% of the total weight of sterile water, stir and ferment at 28-36°C for 16-24 h, and make the bacterial liquid, wherein the total 502897 number of viable bacteria is 6x10°-1x10!!/g;

Pour 13 Kg of the fermented mixed culture medium (with water content of 3 Kg) into 90 Kg of inorganic compound flocculant granules, fully stir for 1 h, and naturally cool and dry at room temperature to obtain slow-release compound flocculant granules with particle size of 0.5-3.0 mm;

Take the mine wastewater discharged from a coal mine, and test it by conventional chemical analysis method, wherein the pH value is 3.0, the total Fe content is 250 mg/L, and the SO4” content is 760 mg/L, leave the wastewater in the regulating tank for 1 hour to balance the water quality and quantity, and preliminarily remove the larger suspended substances in the wastewater, such as coal dust, rock powder, clay and other fine particles, especially coal powder; after the wastewater with balanced water quality enters the coagulation tank, let it stand for 20 minutes, use the powder dosing device, add the slow-release compound flocculant particles of this embodiment at the dosage of 15 g/m°, and stir them mechanically; after settling in the inclined plate sedimentation tank, test the effluent water quality again; as a result, the pH value can be increased to 6.0 left and right, while the total Fe content is reduced to 15 mg/L and the SO4* content is reduced to less than 250 mg/L.

Embodiment 3

Take 15 Kg of fly ash, 15 Kg of peat, 20 Kg of glucose, 30 kg of CaCl; 30 Kg of coal gangue, 7 Kg of activated carbon and 0.04 Kg of ferrous sulphate, stir them evenly, add 20-28 L of water, keep stirring for 20-30 min, carry out disc or extrusion granulation, and dry them to obtain the inorganic compound flocculant with particle size of 0.2-2.5 mm

Take 6.0 Kg of starch, 2.0 Kg of soluble cellulose and 6.0 Kg of beef paste, add 1.0 Kg of Desulfovibrio, 1.0 Kg of colourless sulphur bacteria (including 0.3 Kg of thiobacillusferrooxidans and 0.7 Kg of Acidithiobacillus thiooxidans) and 0.3 Kg of

Gluconobacter, mix them evenly (the number of viable bacteria of each agent is not less than 2x107-2x10%), add 30-40% of the total weight of sterile water, stir and ferment at 28-36°C for 16-24 h, and make the bacterial liquid, wherein the total 502897 number of viable bacteria is 6x10°-1x10!!/g;

Pour 16 Kg of the fermented mixed culture medium (with water content of 3.7

Kg) into 88 Kg of inorganic compound flocculant granules, fully stir for 1 h, and naturally cool and dry at room temperature to obtain slow-release compound flocculant granules with particle size of 0.5-3.0 mm;

Take the mine wastewater discharged from a coal mine, and test it by conventional chemical analysis method, wherein the pH value is 3.0, the total Fe content is 250 mg/L, and the SO4” content is 760 mg/L, leave the wastewater in the regulating tank for 1 hour to balance the water quality and quantity, and preliminarily remove the larger suspended substances in the wastewater, such as coal dust, rock powder, clay and other fine particles, especially coal powder; after the wastewater with balanced water quality enters the coagulation tank, let it stand for 20 minutes, use the powder dosing device, add the slow-release compound flocculant particles of this embodiment at the dosage of 15 g/m°, and stir them mechanically; after settling in the inclined plate sedimentation tank, test the effluent water quality again; as a result, the pH value can be increased to 6.0 left and right, while the total Fe content is reduced to 16 mg/L and the SO4* content is reduced to less than 257 mg/L.

Claims

CLAIMS LU502897

1. À slow-release compound flocculant for reducing the acidity of mine water, comprising 87-95wt% of inorganic compound flocculant and 5-13wt% of soluble coating on the inorganic compound flocculant, wherein the inorganic compound flocculant comprising 40-50 parts by mass of microbial carbon source, 20-35 parts by mass of coagulant aid and 3-10 parts by mass of adsorbent, wherein the soluble coating is a culture medium mixed with microbial inoculum, wherein the microbial inoculum is a mixed inoculum comnprising Desulfovibrio, colourless sulphur bacteria and Gluconobacter, the total number of viable bacteria in each gram of coating is 6x10°-1x10"!, the ratio of viable bacteria among Desulfovibrio, colourless sulphur bacteria and Gluconobacter is (1-1.5):(1-1.5):0.5, and the colourless sulphur bacteria is a mixed bacteria of Thiobacillusferrooxidans and Thiobacillus acidophilus in the mass ratio of (0.2-1):1.

2. The slow-release compound flocculant according to claim 1, characterized in that the microbial carbon source is one or a mixture of fly ash, peat and glucose in any proportion.

3. The slow-release compound flocculant according to claim 2, characterized in that ferric sulphate is added into the microbial carbon source, and the added amount is

0.04-0.2% of the total mass of the microbial carbon source.

4. The slow-release compound flocculant according to claim 1, characterized in that the coagulant aid is a mixture of one or two of CaCl, and bone glue in any proportion.

5. The slow-release compound flocculant according to claim 1, characterized in that the adsorbent is one or a mixture of activated carbon, zeolite, coal gangue and fruit shell in any proportion.

6. The slow-release compound flocculant according to claim 1, characterized in that the culture medium is a mixed culture medium of one or more of starch, soluble cellulose and beef paste culture medium.

7. The slow-release compound flocculant according to claim 1, characterized in 17008807 that the soluble coating is composed of 7-10 parts by mass of culture medium and 1-4 parts by mass of microbial agents.

8. The slow-release compound flocculant according to claim 1, characterized in that the slow-release compound flocculant is spherical or nearly spherical particles with a particle size of 0.5-3.0 mm.