阅读说明：本技术 一种高寒高海拔地区湿污泥制备矿区土壤调理剂的方法 (Method for preparing mining area soil conditioner from wet sludge in alpine and high-altitude areas ) 是由 刘树根 陈越 瞿广飞 彭语欣 孔馨 金熠 于 2021-09-15 设计创作，主要内容包括：本发明公开了一种高寒高海拔地区湿污泥制备矿区土壤调理剂的方法,属于有机固体废物处理及资源化利用技术领域。所述方法步骤如下：待处理湿污泥与干化产物混合调配含水率,之后添加填充剂以及固氮改良剂,所得混合料进行生物干化处理；部分干化料加入重金属去除剂以及调整剂,之后于650-860℃条件下低氧热处理30-60 min；热处理产物经筛分处理后,筛下细微颗粒与干化处理后的另外一部分物料混合。本发明所制备的土壤调理剂在钝化重金属、保水保墒、增强土壤肥力、作物生长方面作用明显。(The invention discloses a method for preparing a mining area soil conditioner from wet sludge in a high-cold high-altitude area, and belongs to the technical field of organic solid waste treatment and resource utilization. The method comprises the following steps: mixing wet sludge to be treated with a drying product to adjust the water content, then adding a filler and a nitrogen fixation modifier, and carrying out biological drying treatment on the obtained mixture; adding a heavy metal remover and a regulator into part of the dried material, and then carrying out low-oxygen heat treatment for 30-60 min at the temperature of 650-860 ℃; after the heat treatment product is screened, undersize fine particles are mixed with the other part of the dried material. The soil conditioner prepared by the invention has obvious effects on passivating heavy metals, retaining water and moisture, enhancing soil fertility and growing crops.)

1. A method for preparing a mining area soil conditioner from wet sludge in a high-cold high-altitude area is characterized by comprising the following steps:

(1) adjusting the moisture content of wet sludge to be treated to 63-68% to obtain a pretreatment material, and mixing the pretreatment material with a filler to prepare a mixture;

(2) adding a nitrogen fixation modifier into the mixture obtained in the step (1), uniformly mixing, and then sending the mixture to a drum-type reactor for biological drying treatment;

(3) adding a heavy metal remover and a heat treatment regulator into part of the dried product obtained in the step (2), and then carrying out low-oxygen heat treatment;

(4) and (3) mixing the heat-treated product obtained in the step (3) with the dried product of the rest part obtained in the step (2), and using the obtained product for restoring and improving the soil of the mining area.

2. The method for preparing the soil conditioner for the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the filler in the step (1) is a mixture of ceramsite and highland barley straws, and the mass ratio of the filler to the pretreatment material is 1: (8-20).

3. The method for preparing the soil conditioner in the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the length of the highland barley straws in claim 2 is 3-6 cm, and the mass ratio of the highland barley straws to the ceramsite is 1: (1-2).

4. The method for preparing the soil conditioner in the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein iron trichloride salts are added in the step (2) as a nitrogen fixation modifier, and the mass ratio of the nitrogen fixation modifier to the mixture is 1 (30-50).

5. The method for preparing the soil conditioner of the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the air exhaust intensity of the biological drying reactor in the step (2) is 0.3-0.9min^-1 kg^-1The drum reactor takes 6-12 minutes to make one turn.

6. The method for preparing the soil conditioner for the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the heavy metal remover in the step (3) is CaCl₂、MgCl₂Any one or combination of the two, heavy metal remover and dried productThe mass ratio of (1): (70-100).

7. The method for preparing the mining area soil conditioner from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the heat treatment regulator is palygorskite mineral powder, and the mass ratio of the palygorskite mineral powder to the dried product is 1: (15-30).

8. The method for preparing the soil conditioner in the mining area from the wet sludge in the alpine and high-altitude areas as claimed in claim 1, wherein the temperature of the low-oxygen heat treatment in the step (3) is 650-.

9. The method for preparing the soil conditioner of the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the partial drying product obtained in the step (3) is 40-50% of the drying product obtained in the step (2).

10. The method for preparing the soil conditioner in the mining area from the wet sludge in the alpine and high-altitude areas according to claim 1, wherein the heat treatment product in the step (4) needs to be subjected to screening treatment, the obtained coarse particles are returned to the step (1) to be used as a filling agent, and the rest of undersize fine particles are mixed with the rest of the dried product in the step (2), and the screening treatment is carried out by using a vibrating screen with the screen hole diameter of 10 mm.

Technical Field

The invention belongs to the technical field of organic solid waste treatment and resource utilization, and particularly relates to a method for preparing a mining area soil conditioner from wet sludge in a high-cold high-altitude area.

Background

With the increasing population and the continuous promotion of urbanization process in China, the living standard of the China is continuously improved, and the sludge production is continuously increased. Calculated according to that 10000 tons of sewage generate 5 tons of sludge, the sludge yield in 2017 years in the high-cold high-altitude Lasa area reaches 8.23 multiplied by 10⁴t (water content 80%). Although the landfill is a typical mode of sludge disposal, the sludge has high moisture content, occupies the storage capacity during the landfill, has the problems of obvious collapse of a landfill operation area, and effectively solves the sludge routing problem, which is a difficult problem to be solved urgently by a sewage treatment plant.

The compost treatment of sludge for agriculture is one of the treatment and disposal methods. The sludge contains rich components such as nitrogen, phosphorus and organic matters, and can provide a good external environment for soil improvement and plant growth. However, when nutrient substances in the sludge are directly used for agriculture, the plant absorption and utilization rate is low, the sludge may contain harmful substances such as heavy metals, organic pollutants, pathogenic bacteria and the like, potential environmental risks exist, the health and the ecological environment of human beings are influenced, and sludge treatment products specified in China cannot enter a food chain.

The prior patent ZL201710530980.X discloses a method for producing a soil conditioner by using poultry and livestock manure, which comprises the steps of mixing and fermenting bacillus subtilis microbial bacteria and the like to prepare decomposed strains, then mixing the decomposed strains with water, adding chicken manure and pig manure compost to prepare composite microbial bacteria, uniformly mixing the composite microbial bacteria with leaf mold and green zeolite to prepare soil powder, and then putting the powder into a bucket for culturing to prepare the soil conditioner. Patent ZL201710787362.3 discloses a limestone mining area ecological restoration method, which uses lime pit slag as a base material, is supplemented with a small amount of loam, ecological organic fertilizer and the like, and is matched with alfalfa and lavender for planting, so that the purpose of mining area ecological restoration is achieved. Patent ZL202011085270.9 discloses a soil microorganism culture method for improving soil in alpine and high-altitude areas, which comprises the steps of mixing enriched and cultured microorganisms with a liquid culture medium, spraying the mixture into soil in alpine and high-altitude areas, turning the soil over, spraying straw pulp on the surface of the soil, enhancing the soil fertility and promoting the growth of crops.

Generally, the climate conditions in the alpine and high-altitude areas are severe, the ecological environment is fragile, the organic matter content in the soil in the mining area is obviously insufficient, the microbial population structure is single, the microbial quantity is obviously low, and the ecological environment restoration in the mining area is relatively more difficult. The method takes sludge to be treated urgently as a source, adds the special crop straws in the area for mixed composting treatment, improves the performance of the compost product by adding the ferric salt nitrogen fixation agent, the heavy metal remover, the heat treatment regulator and the like, has high humification degree and high nitrogen and phosphorus content of the obtained product, has good solidification effect on potential heavy metals, and can be widely applied to ecological environment restoration in mining areas.

Disclosure of Invention

The invention aims to provide a method for preparing a mining area soil conditioner by wet sludge in alpine and high-altitude areas, wherein the wet sludge generated by a sewage treatment plant in the area is pretreated, then a nitrogen fixation modifier is added, and biological drying treatment is carried out after uniform mixing; then adding a part of the dried product into a heavy metal remover and regulator palygorskite mineral powder for low-oxygen heat treatment; the obtained product is screened, and the fine material is mixed with the other part of the original dried product. The prepared soil conditioner meets the standards of 'sludge quality for soil improvement in sludge treatment in urban sewage treatment plants' GB/T24600-.

The object of the invention is achieved by the following steps:

(1) adjusting the moisture content of wet sludge to be treated to 63-68% to obtain a pretreatment material, and mixing the pretreatment material with a filler to prepare a mixture;

(2) adding a nitrogen fixation modifier into the mixture obtained in the step (1), uniformly mixing, and then sending the mixture to a drum-type reactor for biological drying treatment;

(3) adding a heavy metal remover and a heat treatment regulator into part of the dried product obtained in the step (2), and then carrying out low-oxygen heat treatment;

(4) and (3) mixing the heat-treated product obtained in the step (3) with the dried product of the rest part obtained in the step (2), and using the obtained product for restoring and improving the soil of the mining area.

Preferably, the filler in the step (1) is a mixture of ceramsite and highland barley straw, and the mass ratio of the filler to the pretreatment material is 1: (8-20), the light highland barley straws with certain strength are added into the pile body on the basis of the ceramsite, so that the filling effect is better.

Preferably, the length of the highland barley straws is 3-6 cm, and the mass ratio of the highland barley straws to the ceramsite is 1: (1-2).

Preferably, the nitrogen fixation modifier in the step (2) is ferric trichloride salt, and the mass ratio of the ferric trichloride salt to the pretreatment material is 1: (30-50); fe³⁺Can fix ammonium nitrogen to prevent nitrogen loss by combining with organic acid in compost materials; in addition, FeCl₃Has polymerization function, can be chelated with humic acid in the compost body to adsorb phosphorus, and improves the quality of compost products.

Preferably, the air exhaust intensity of the biological drying reactor in the step (2) is 0.3-0.9min^-1 kg^-1The drum reactor takes 6-12 minutes to make one turn.

Preferably, the heat treatment regulator is palygorskite mineral powder, and the mass ratio of the palygorskite mineral powder to the dried product is 1: (15-30); further, the mass ratio of the palygorskite mineral powder to the dried product is 1: (20-24); the addition of the palygorskite mineral powder obviously promotes the adsorption effect of the low-oxygen heat treatment product on heavy metals, and enhances the effect of passivating the metals when the palygorskite mineral powder is applied to an ore region.

Preferably, the heavy metal remover in the step (3) is CaCl₂、MgCl₂Any one or the combination of the two, the mass ratio of the heavy metal remover to the dried product is 1: (70-100); added CaCl₂Or MgCl₂Decomposing by oxygen to separate out chlorine, and then reacting heavy metal oxide with chlorine: MeO + Cl₂=MeCl₂+1/2O₂With MeCl₂And the heavy metal possibly existing in the raw material is removed when the raw material enters a gas phase at high temperature.

Preferably, the low-oxygen heat treatment temperature in the step (3) is 650-.

Furthermore, the low-oxygen heat treatment temperature in the step (3) is 750-.

Preferably, the part of the dried product obtained in the step (3) is 40-50% of the dried product obtained in the step (2).

Preferably, the heat-treated product in step (4) needs to be subjected to screening treatment, the obtained coarse particles are returned to step (1) as a filler, and the rest undersize fine particles are mixed with the rest of the dried product in step (2), wherein the screening treatment is performed by using a vibrating screen with the screen hole diameter of 10 mm.

The invention has the beneficial effects that:

1) the wet sludge is subjected to biological drying treatment, so that the pathogenic microorganisms can be effectively killed at high temperature, the moisture can be removed more obviously, the formed humus has obvious effects on the aspects of preserving moisture and soil fertility, and the heavy metal possibly existing in the process of improving the soil in the mining area can be solidified.

2) When the wet sludge is dried, ferric trichloride salt is added as a nitrogen fixing agent, the nitrogen content of the product is high, and the ferric trichloride salt can be chelated with humic acid to adsorb phosphorus, so that the quality of the compost product is improved.

3) Adding a heavy metal remover and a regulator in the low-temperature heat treatment process, converting heavy metal oxides into corresponding chlorides to enter tail gas, and removing a little heavy metal originally existing in the sludge; in addition, the regulator and the sludge form a carbon-containing magnesium, aluminum and silicon compound during low-oxygen heat treatment, and the passivation effect on heavy metals is obvious when the regulator and the sludge are used for restoring and improving the soil in a mining area.

Detailed Description

The present invention is described in detail with reference to the following specific examples, which are carried out on the premise of the technical solution of the present invention, and the detailed implementation manner and the specific operation process are given, but the protection scope of the present invention is not limited to the contents.

Example 1

Mixing dewatered sludge (water content of about 81%) and dried sludge (water content of about 22%) in urban sewage plant to prepare pretreatment material with water content of 65%, treating highland barley straw into 4 cm small segments, mixing with ceramsite by mass ratio to form filler, uniformly mixing the obtained filler and pretreatment material by 1/20 mass ratio, adding FeCl according to pretreatment material mass 1/40₃Then the mixture is sent to a drum-type biological drying device for treatment, the rotating speed of the drum is set to be 7 r/min, and the air extraction intensity of one side of the drying device is 0.3L min^-1 kg^-1。

After biological drying treatment, a dried product with the water content of 54 percent is obtained, and 50 percent of the dried product is taken to be subjected to low-oxygen heat treatment. Before heat treatment, CaCl is added into the dried product₂And palygorskite mineral powder, wherein the proportion of the palygorskite mineral powder to the dried material is respectively 1: 80. 1: 20. the mixed material is thermally treated in a reaction furnace at 700 ℃ for 50 min, the oxygen content in the tail gas at the outlet of the reaction furnace is monitored, and the air supply quantity at the inlet is adjusted by the level of 0.8 percent of the oxygen concentration in the tail gas.

And (3) uniformly mixing the heat-treated product with the other 50% of dried product to obtain the prepared soil conditioner, wherein the nitrogen content and the phosphorus content are respectively 2.1% and 5.5%, the lead content and the copper content in each kilogram of material are respectively 400 mg and 800 mg, other heavy metals are low to undetectable levels, and nutrient indexes and pollutant limit values meet the standards of 'sludge for treating sludge in urban sewage treatment plants' GB/T24600 plus 2009 for land improvement.

Example 2

Mixing dewatered sludge (water content of about 82%) and dried sludge (water content of about 21%) in urban sewage plant to prepare pretreatment material with water content of 64%, treating highland barley straw into small segments of 3 cm, mixing the small segments with ceramsite in equal mass ratio to form filler, uniformly mixing the obtained filler and the pretreatment material in 1/12 mass ratio, adding FeCl according to pretreatment material mass 1/35₃Then the mixture is sent to a drum-type biological drying device for treatment, the rotating speed of the drum is set to be 12 r/min, and the air extraction intensity of one side of the drying device is 0.7L min^-1 kg^-1。

After biological drying treatment, a dried product with the water content of 52 percent is obtained, and the dried product with the water content of 40 percent is taken to be subjected to low-oxygen heat treatment. Before heat treatment, CaCl is added into the dried product₂And palygorskite mineral powder, wherein the proportion of the palygorskite mineral powder to the dried material is respectively 1: 90. 1: 15. the mixed material is thermally treated in a reaction furnace at 800 ℃ for 30 min, and the air supply quantity at the inlet is adjusted according to the level of 0.6 percent of oxygen concentration in tail gas.

And (3) uniformly mixing the heat-treated product with the other 60% of dried product to obtain the prepared soil conditioner, wherein the nitrogen content and the phosphorus content are respectively 2.3% and 5.0%, the lead content and the copper content in each kilogram of material are respectively 360 mg and 730 mg, other heavy metals are low to the undetectable level, and the nutrient index and the pollutant limit value meet the standards of GB/T24600-.

Example 3

Mixing dewatered sludge (water content of about 83%) and dried sludge (water content of about 21%) in an urban sewage plant to prepare a pretreatment material with water content of 65%, processing highland barley straws into small segments of 5 cm, mixing the small segments with ceramsite according to a mass ratio of 1:2 to form a filler, uniformly mixing the obtained filler and the pretreatment material according to a mass ratio of 1/18, adding FeCl according to the mass of 1/45 of the pretreatment material₃Then the mixture is sent to a drum-type biological drying device for treatment, the rotating speed of the drum is set to be 10 r/min, and the air extraction intensity of one side of the drying device is 0.9L min^-1 kg^-1。

After biological drying treatment, a dried product with the water content of 53 percent is obtained, and the dried product with the water content of 50 percent is taken to be subjected to low-oxygen heat treatment. Before heat treatment, adding a heavy metal remover and palygorskite mineral powder into a dried product, wherein the ratio of the heavy metal remover to the palygorskite mineral powder to the dried product is 1: 70. 1: 25, wherein the heavy metal remover is CaCl₂、MgCl₂Mixing the components in equal mass. The mixed material is thermally treated in a reaction furnace at 860 ℃ for 30 min, and the air supply quantity at the inlet is adjusted according to the level of 0.4 percent of oxygen concentration in tail gas.

And (3) uniformly mixing the heat-treated product with the other 50% of dried product to obtain the prepared soil conditioner, wherein the nitrogen content and the phosphorus content are respectively 1.9% and 5.5%, the lead content and the copper content in each kilogram of material are respectively 350 mg and 720 mg, other heavy metals cannot be detected, and the nutrient index and the pollutant limit value meet the standards of GB/T24600-.

Example 4

Mixing dewatered sludge (the water content is about 83%) of an urban sewage plant with dried sludge (the water content is about 21%) to prepare a pretreatment material with the water content of 64%; processing the highland barley straws into 5 cm small sections, mixing the highland barley straws with ceramsite according to the mass ratio of 1:2 to form a filler, and mixing the filler and the pretreatment material in a ratio of 1: 15, adding FeCl according to the mass of 1/50 of the pretreated material₃Then the mixture is sent to a drum-type biological drying device for treatment, the rotating speed of the drum is set to be 10 r/min, and the air extraction intensity at one side of the drying device is 1L min^-1 kg^-1。

After biological drying treatment, a dried product with the water content of 51% is obtained, and 50% of the dried product is taken to be subjected to low-oxygen heat treatment. Before heat treatment, adding a heavy metal remover and palygorskite mineral powder into a dried product, wherein the ratio of the heavy metal remover to the palygorskite mineral powder to the dried product is 1: 95. 1: 25, wherein the heavy metal remover is CaCl₂、MgCl₂Mixing the components in equal mass. The mixed material is thermally treated in a reaction furnace at 860 ℃ for 30 min, and the air supply quantity at the inlet is adjusted according to the level of 0.4 percent of oxygen concentration in tail gas.

And (3) passing the heat-treated product through a vibrating screen with 10mm sieve pores, returning the part above the sieve to the pretreatment material as a filler, and uniformly mixing the part below the sieve with the other 50% of dried product to obtain the prepared soil conditioner, wherein the nitrogen content and the phosphorus content are respectively 2.5% and 6%, the lead content and the copper content in each kilogram of the material are respectively 290 mg and 650 mg, other heavy metals cannot be detected, and the nutrient index and the pollutant limit value meet the standards of GB/T24600 plus 2009.