Solid bacterial block for treating acid mine wastewater as well as preparation method and application of solid bacterial block

Abstract

The invention discloses a solid bacterial block for mine acid wastewater treatment and a preparation method and application thereof, and relates to the technical field of acid wastewater treatment. The solid bacterial block is prepared from the following components in parts by mass: 100 to 150 parts of a microbial agent, 50 to 100 parts of a nutritional component, 200 to 300 parts of a carrier and 50 to 100 parts of a binder. The microbial agent, the nutritional components, the carrier and the binder are mixed in proportion and compressed into blocks to form solid bacterial blocks. The solid bacterial block provided by the invention is high in activity, simple to use, long in lasting period and stable, can be directly put into an acid water reactor for use after a membrane is detached, and can efficiently remove heavy metals in the mine acid wastewater; the problems of poor acid water impact resistance, slow environmental adaptation, limited treatment efficiency, large packaging volume, high transportation cost and the like of a traditional liquid microbial agent are well solved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a solid bacterial block for treating acid mine wastewater, and a preparation method and application thereof. Background Art

[0002] Heavy metal pollution has become a major environmental problem facing my country. Mining activities are the main source of heavy metal pollution, which mainly releases pollution to the surrounding environment in the form of acid mine drainage (AMD), seriously affecting farmland soil quality, drinking water safety and residents' health.

[0003] Acid mine drainage usually has a low pH value, even below 2.0, and a high content of heavy metal ions, making it one of the main sources of mine pollution. In my country alone, the annual discharge of acid mine drainage reaches 3.6 billion tons, so there is a huge demand for treatment. The most commonly used treatment technology at present is the neutralization method, but it has problems such as severe scaling, huge sludge production, and high treatment costs, making it difficult for mining companies to apply and unbearable in the long term. The microbial method has the advantages of low investment cost, environmental friendliness, and low sludge volume, and is currently the most promising treatment technology. The microbial method mainly uses sulfate-reducing bacteria to treat acidic wastewater through biological sulfidation. This technology has the following disadvantages. On the one hand, the heavy metal ions and extreme acidity in acidic mine wastewater will limit the growth and reproduction of microorganisms. If the sulfate-reducing bacteria solution is directly added to the acidic mine wastewater, it will affect the impact resistance of the sulfate-reducing bacteria, reduce the activity of the sulfate-reducing bacteria, and lead to low efficiency in acid water treatment. On the other hand, traditional microbial agents are mainly liquid products, with high packaging costs and inconvenient transportation, which limit the practical application of microbial treatment methods. Summary of the invention

[0004] In view of the above problems, the present invention proposes a solid bacterial block for treating acid mine wastewater, and a preparation method and application thereof, which has high treatment efficiency and can effectively remove heavy metals in acid mine wastewater.

[0005] One of the purposes of the present invention is to provide a solid bacterial block for treating acid mine wastewater.

[0006] The technical solution adopted by the present invention is as follows: a solid bacterial block for treating acid mine wastewater is composed of 100-150 parts of microbial agents, 50-100 parts of nutrient components, 200-300 parts of carriers, and 50-100 parts of binders by mass.

[0007] The microbial agent is a preparation containing acidophilic sulfate-reducing bacteria.

[0008] Acidophilic sulfate-reducing bacteria can tolerate acidity down to pH 3.5.

[0009] The nutritional components include one or a combination of two or more of sugar residue, wheat bran, rice husk, livestock and poultry excrement, etc. In one embodiment, the nutritional components are sugar residue, wheat bran, rice husk and livestock and poultry excrement, wherein the mass ratio of sugar residue: wheat bran: rice husk: livestock and poultry excrement is 20-25:10-15:5-10:50-60.

[0010] The carrier includes one or a combination of two or more of grass fiber, wood fiber, bagasse, and corn stalks. In one embodiment, the carrier is grass fiber, wood fiber, bagasse, and corn stalks, wherein the mass ratio of grass fiber: wood fiber: bagasse: corn stalks is 40-50: 30-40: 5-10: 10-20.

[0011] The adhesive is a special adhesive for spraying.

[0012] The second object of the present invention is to provide a method for preparing the solid mushroom block.

[0013] The technical solution adopted by the present invention is as follows: A method for preparing a solid bacterial block for treating acid mine wastewater comprises the following steps:

[0014] (1) Preparation of microbial agents: enrich and culture acidophilic sulfate-reducing bacteria until the effective viable count is not less than 10 7 cfu / g, and then centrifuge and discard the supernatant to obtain a bacterial sludge mixture 1; then wash the bacterial sludge mixture 1 with 0.01M PBS buffer solution, centrifuge and remove the supernatant to obtain a bacterial sludge mixture 2; then mix the bacterial sludge mixture 2 with the nutrient solution in a ratio of 1:10 to 1:20 to obtain a microbial agent for use.

[0015] (2) Preparation of nutritional components: Prepare nutritional components by taking one or more of sugar residue, wheat bran, rice husk, livestock and poultry manure, etc. for later use.

[0016] (3) Preparing a carrier: Prepare a carrier from one or more of grass fiber, wood fiber, bagasse, and corn stalks for later use.

[0017] (4) Weigh 50 to 100 parts of nutrient components, 200 to 300 parts of carriers, 50 to 100 parts of binders, etc. as base materials, mix and stir them evenly, and weigh 100 to 150 parts of microbial agents for later use.

[0018] (5) The base material weighed in step (4) is mixed and stirred evenly, and then the microbial agent weighed in step (4) is added according to the mass ratio, and compressed and packaged to form a cylindrical bacterial block.

[0019] In step (1), the nutrient solution serves to maintain the carbon source, salts, and thickeners required for the growth of the bacterial agent. The composition includes 2 g / L of yeast extract, 1 g / L of glycerol, (NH 4 ) 2 SO 4 1.5 g / L, 2 g / L of sodium alginate, and the pH is adjusted to 4 - 5, which is suitable for the growth of acidophilic sulfate-reducing bacteria.

[0020] In step (1), the acid resistance of acidophilic sulfate-reducing bacteria can be as low as pH 3.5.

[0021] In step (1), the centrifugation conditions are: 8000 - 10000 rpm, 5 - 10 min.

[0022] In step (2), the sugar residue, wheat bran, rice husk, and livestock and poultry manure are formulated into the nutrient component according to the mass ratio of 20 - 25:10 - 15:5 - 10:50 - 60.

[0023] In step (3), the grass fiber, wood fiber, bagasse, and corn straw are formulated into the carrier according to the mass ratio of 40 - 50:30 - 40:5 - 10:10 - 20.

[0024] In step (5), the bacterial blocks are divided into three specifications: large, medium, and small. The size of the large-sized bacterial block is usually 40 cm in diameter × 50 cm in height, and the weight is 28 - 30 kg; the size of the medium-sized bacterial block is usually 30 cm in diameter × 40 cm in height, and the weight is 12 - 13 kg; the size of the small-sized bacterial block is usually 20 cm in diameter × 30 cm in height, and the weight is 4.0 - 4.5 kg. The specific specifications are determined according to the on-site use situation.

[0025] The third object of the present invention is to provide the application of the above solid bacterial block.

[0026] The technical solution adopted by the present invention is as follows: the application of the solid bacterial block for treating mine acid wastewater. The solid bacterial block is transported to the mine, and after removing the film, it is added to the mine acid wastewater sump or the acid wastewater treatment pool. The dosage of the bacterial block is 10 - 20 kg / m 3 , and to ensure the activity of the bacterial agent, it should be put into use within 1 month after the preparation of the bacterial block, and the treatment time is usually 10 - 15 d.

[0027] The bacterial blocks are arranged side by side in a single layer or stacked in a multi-layer "pin" shape and soaked in the acid wastewater, which can not only ensure the stability and firmness of the stacking of the bacterial blocks, but also utilize the gaps formed by the carriers such as grass fiber, wood fiber, bagasse, and corn straw to provide a buffer space for the bacterial agent, improve the impact resistance of the bacterial agent in the acid water, and contribute to the rapid growth and reproduction of the bacterial agent in the wastewater.

[0028] The bacterial block carriers prepared by the present invention are all composed of easily degradable agricultural wastes and can be used as microbial carbon sources. Therefore, when the bacterial blocks prepared by the present invention are used to treat acidic wastewater, the slag production is small and there is no pressure for later slag removal. The present invention can achieve harmless treatment of acidic mine wastewater.

[0029] (1) The solid bacterial block for treating acid mine wastewater provided by the present invention contains a dry powder bacterial agent, which has a higher concentration and stronger activity than the traditional liquid bacterial agent, and has a higher efficiency in removing heavy metals in acid mine wastewater. The pH can be raised from acidic to neutral, and the reduction of major heavy metals such as Pb, Zn, Cu, and Cd exceeds 90%.

[0030] (2) Compared with traditional liquid bacterial agents, the solid bacterial blocks provided by the present invention are smaller in size, more regular in shape, and easier to transport, thus greatly reducing storage and transportation costs.

[0031] (3) The solid mushroom block provided by the present invention has no odor, is easy to use and operate, does not require the addition of an additional carbon source, and has no slag cleaning pressure and secondary pollution, thereby greatly reducing the cost of treating acid mine wastewater. DETAILED DESCRIPTION

[0032] Embodiment 1

[0033] The implementation site is located in a polymetallic mine in Shaoguan, Guangdong. A concrete pool was built in a dump area as a reaction pool. The reaction pool is 5.4m long × 3.6m wide × 1.8m deep, with a bottom plate and pool wall thickness of 20cm and an effective capacity of 24m 3 The acid water comes from the drainage of the mine, is dark red, and has a pH as low as 3.1. The technology of the present invention is used to treat the wastewater from the mine in the treatment pool. The specific steps are as follows:

[0034] (1) Preparation of microbial agents: enrichment and culture of acidophilic sulfate-reducing bacteria. The acid resistance of acidophilic sulfate-reducing bacteria can be as low as pH 3.5. The effective viable count was tested to reach 3.5×10 7 cfu / g, centrifuge the bacterial solution at 10000rpm for 5min, discard the supernatant, and obtain bacterial sludge mixture 1; then wash the bacterial sludge mixture 1 with 0.01M PBS buffer solution, centrifuge it at 10000rpm for 5min, and discard the supernatant to obtain bacterial sludge mixture 2; then mix the bacterial sludge mixture 2 with the nutrient solution at a ratio of 1:20 to obtain a microbial agent for standby use. The nutrient solution ingredients are: yeast extract 2g / L, glycerol 1g / L, (NH 4 ) 2 SO 4 1.5g / L, sodium alginate 2g / L, pH 5.

[0035] (2) Prepare the nutrient component in reserve by mixing sugar residue, wheat bran, rice husk and livestock manure according to the mass ratio of 25﹕10﹕5﹕60.

[0036] (3) Prepare the carrier in reserve by mixing grass fiber, wood fiber, bagasse and corn straw according to the mass ratio of 45﹕40﹕5﹕10.

[0037] (4) Weigh 100 parts of the nutrient component, 300 parts of the carrier, 100 parts of the binder, etc. respectively by weight as the base material, and mix and stir them evenly. In addition, weigh 150 parts of the microbial inoculum in reserve.

[0038] (5) Mix and stir the base material weighed in step (4) evenly, add it to the bottom of the conveyor belt of the silage packing and wrapping machine, and add the microbial inoculum weighed in step (4) to the top of the conveyor belt according to the mass ratio. The base material and the microbial inoculum enter the packing machine for compression and packing to form a cylindrical bacterial block, and are hermetically packaged by the wrapping machine to form a separately wrapped bacterial block of small size for reserve.

[0039] Transport the prepared bacterial blocks to the test site, remove the film and put them into the acidic water pit by manual delivery. The dosage of the bacterial blocks is 15 kg / m 3 , and distribute them in areas, stacking them in a four-layer "pin" shape. A total of 80 small-sized bacterial blocks are put in.

[0040] After 10 days, take samples of the wastewater in the treatment pond for detection. According to the detection results, the water quality of the mine wastewater treated by the technology of the present invention has been significantly improved. The pH has risen from 3.1 to neutral, and the reduction amounts of the main heavy metals such as Pb, Zn, Cu, Cd, and As all exceed 90%. Table 1 shows the water quality detection results of the reaction pond after 10 days of treatment.

[0041] Table 1 Comparison of water quality of acidic wastewater from a certain mine in Shaoguan before and after treatment (unit: mg / L)

[0042] Detection indicators pH Pb Zn Cu Cd As Before treatment 3.1 0.8 150.2 22.3 0.81 0.68 After treatment 6.9 0.03 1.0 0.76 0.003 0.04

[0043] Example 2

[0044] The implementation site is located in a heavy metal mine in Shangrao, Jiangxi. Select an acidic water pit below a certain waste dump site as the test area. The acidic water pit is formed by the surface seepage water of the waste dump site. The surface area of the water pit is about 200 m 2 , and the average water depth is about 2.5 m. After detection, the average pH of the water quality of the water pit is 3.7, and the contents of lead, zinc, copper, and cadmium are 0.39 mg / L, 80 mg / L, 41.4 mg / L, and 0.11 mg / L respectively. Use the technology of the present invention to treat the wastewater in the acidic water pit. The specific steps are as follows:

[0045] (1) Prepare the microbial inoculum: Enrich and culture the acidophilic sulfate-reducing bacteria. After detection, the effective viable count reaches 1.2×107 cfu / g, centrifuge the bacterial liquid at 8000 rpm for 10 min, discard the supernatant to obtain bacterial sludge mixture 1; then wash bacterial sludge mixture 1 with 0.01M PBS buffer solution, centrifuge at 8000 rpm for 10 min and then discard the supernatant to obtain bacterial sludge mixture 2; then mix bacterial sludge mixture 2 with nutrient solution (yeast extract 2 g / L, glycerol 1 g / L, (NH 4 ) 2 SO 4 1.5 g / L, sodium alginate 2 g / L, pH 4) in a ratio of 1:10 to obtain the microbial inoculant for standby.

[0046] (2) Prepare the nutrient components by mixing sugar residue, wheat bran, rice husk and livestock manure in a mass ratio of 20﹕15﹕10﹕55 for standby.

[0047] (3) Prepare the carrier by mixing straw fiber, wood fiber, bagasse and corn straw in a mass ratio of 40﹕30﹕10﹕20 for standby.

[0048] (4) Weigh 50 parts of nutrient components, 200 parts of carrier, 50 parts of binder, etc. respectively as the base material and mix and stir evenly. In addition, weigh 100 parts of microbial concentrated bacterial slurry for standby.

[0049] (5) Mix and stir the base material weighed in step (4) evenly, add it to the bottom of the conveyor belt of the silage packing and wrapping machine, and add the concentrated bacterial slurry weighed in step (4) at the top of the conveyor belt according to the mass ratio. The base material and the concentrated bacterial slurry enter the packing machine for compression and packing to form cylindrical bacterial blocks, and are hermetically packaged by the wrapping machine to form separate bacterial block packages of three specifications: large, medium and small for standby.

[0050] Transport the prepared bacterial blocks to the test site, remove the film and put them into the acidic water pit manually + mechanically. The dosage of bacterial blocks is 10 kg / m 3 , distributed by area, stacked in a double-layer "pin" shape. A total of 100 large-sized bacterial blocks, 150 medium-sized bacterial blocks and 100 small-sized bacterial blocks are put in.

[0051] After 15 days, take samples of the wastewater in the treatment pool for detection. According to the detection results, the water quality of the mine wastewater treated by the present invention has been significantly improved. The pH has risen from 3.7 to neutral, and the reduction amounts of main heavy metals such as Pb, Zn, Cu, Cd, etc. all exceed 95%. Table 2 shows the water quality detection results of the acidic water pit after 15 days of treatment.

[0052] Table 2 Comparison of water quality of acidic wastewater from a certain mine in Shangrao before and after treatment (unit: mg / L)

[0053] Detection indicators pH Pb Zn Cu Cd Before treatment 3.7 0.39 80 41.4 0.11 After treatment 7.3 ND 0.33 0.55 0.002

[0054] Note: ND means not detected, the result is below the detection limit.

[0055] The above are only preferred embodiments of the present invention, and the patent protection scope of the present invention is not limited thereto. Any equivalent structural transformations made using the contents of the present invention specification, directly or indirectly used in other related technical fields, are also included in the protection scope of the present invention.

Claims

1. A solid bacterial block for treating acid mine wastewater, characterized in that: It is composed of 100 - 150 parts by mass of microbial inoculum, 50 - 100 parts of nutrient components, 200 - 300 parts of carrier, and 50 - 100 parts of binder.

2. The solid bacterial block for treating acid mine wastewater according to claim 1, characterized in that: The microbial inoculum is a preparation containing acidophilic sulfate-reducing bacteria; the nutrient components include one or more combinations of sugar residue, wheat bran, rice husk, livestock and poultry manure, etc.; the carrier includes one or more combinations of straw fiber, wood fiber, bagasse, corn straw, etc.

3. The solid bacterial block for treating acid mine wastewater according to claim 1, characterized in that: The nutrient components are sugar residue, wheat bran, rice husk and livestock and poultry manure. Among them, the mass ratio of sugar residue: wheat bran: rice husk: livestock and poultry manure is 20 - 25:10 - 15:5 - 10:50 - 60; the carrier is straw fiber, wood fiber, bagasse and corn straw. Among them, the mass ratio of straw fiber: wood fiber: bagasse: corn straw is 40 - 50:30 - 40:5 - 10:10 - 20.

4. A method for preparing a solid bacterial block for treating acid mine wastewater, characterized in that: It includes the following steps: (1) Preparation of microbial agents: enrich and culture acidophilic sulfate-reducing bacteria until the effective viable count is not less than 10 7 cfu / g, then centrifuged and discarded the supernatant to obtain a bacterial sludge mixture 1; then the bacterial sludge mixture 1 was washed with a 0.01M PBS buffer solution, centrifuged and discarded the supernatant to obtain a bacterial sludge mixture 2; then the bacterial sludge mixture 2 was mixed with a nutrient solution at a ratio of 1:10 to 1:20 to obtain a microbial agent; (2) Prepare the nutrient components: Take one or more of sugar residue, wheat bran, rice husk, livestock and poultry manure, etc. to prepare the nutrient components; (3) Prepare the carrier: Take one or more of straw fiber, wood fiber, bagasse, corn straw, etc. to prepare the carrier; (4) Weigh 50 - 100 parts of nutrient components, 200 - 300 parts of carrier, and 50 - 100 parts of binder by mass as the base material, and weigh another 100 - 150 parts of microbial inoculum; (5) Mix and stir the base material weighed in step (4) evenly, and then add the microbial inoculum weighed in step (4) according to the mass ratio, and compress and pack to form a cylindrical bacterial block.

5. The method for preparing the solid bacterial block for treating acid mine wastewater according to claim 4, characterized in that: In step (1), the composition of the nutrient solution includes 2 g / L of yeast extract, 1 g / L of glycerol, 1.5 g / L of (NH4)2SO4, and 2 g / L of sodium alginate, and it is adjusted to the suitable growth pH 4 - 5 of acidophilic sulfate-reducing bacteria.

6. The method for preparing the solid bacterial block for treating acid mine wastewater according to claim 4, characterized in that: In step (1), the acid resistance of acidophilic sulfate-reducing bacteria can be as low as pH 3.5; centrifugation conditions: 8000 - 10000 rpm, 5 - 10 min.

7. The method for preparing the solid bacterial block for treating acid mine wastewater according to claim 4, characterized in that: In step (2), the sugar residue, wheat bran, rice husk and livestock and poultry manure are prepared into nutrient components according to the mass ratio of 20 - 25:10 - 15:5 - 10:50 - 60; In step (3), the straw fiber, wood fiber, bagasse and corn straw are prepared into the carrier according to the mass ratio of 40 - 50:30 - 40:5 - 10:10 - 20.

8. The method for preparing the solid bacterial block for treating acid mine wastewater according to claim 4, characterized in that: In step (5), the solid bacterial blocks are divided into three specifications: large, medium and small. The large-size specification is 40 cm in diameter × 50 cm in height, and the weight is 28 - 30 kg; the medium-size specification is 30 cm in diameter × 40 cm in height, and the weight is 12 - 13 kg; the small-size specification is usually 20 cm in diameter × 30 cm in height, and the weight is 4.0 - 4.5 kg.

9. The use of the solid bacterial block for treating acid mine wastewater according to any one of claims 1 to 3, characterized in that: The solid bacterial block is transported to the mine, and after the membrane is removed, it is added to the mine acid wastewater accumulation pit or acid wastewater treatment pool. The solid bacterial block is added in an amount of 10-20 kg / m 3 The processing time is usually 10 to 15 days.

10. The use of solid bacterial blocks for treating acid mine wastewater according to claim 9, characterized in that: The solid bacterial blocks are put into use within 1 month after being prepared; the solid bacterial blocks are soaked in acidic wastewater in a single-layer side-by-side arrangement or a multi-layer "pin" shape stacking.