CN102220134B - Water retaining SAP (Super Absorbent Polymer)-mixed soil prepared by using biogass fermentative residues and preparation method thereof - Google Patents

Abstract

The invention provides a method for preparing water-retaining mixed agent soil from biogas fermentation residues, by mixing biogas residues, sawdust, bone meal, and soil for crushing, adding swollen water-retaining agents to the mixture, and adding biogas slurry to stir evenly , after 20-30 days of anaerobic fermentation at normal temperature, the water-retaining mixed soil prepared from the residue of biogas fermentation is obtained. The preparation method is fast, simple and low in cost, and realizes the comprehensive utilization, resource utilization, reduction and harmlessness of the biogas fermentation residue. The obtained water-retaining mixed soil has the following characteristics: it can quickly absorb rainwater and irrigation water and store them to ensure the water required for normal plant growth; ensure that the soil remains moist for a long time; it has light load, low bulk density and large porosity; comprehensive nutrients, It has both slow-acting and quick-acting nutrients; it can maintain its stability and high efficiency under various plants and different climatic conditions; it saves fertilizers and pesticides; it is non-toxic, harmless, has no side effects, and does not cause any pollution to the environment.

Description

Water-retaining mixed soil prepared from biogas fermentation residue and method thereof

technology neighborhood

The invention relates to a high-efficiency composite water-retaining mixed agent soil for greening soil and stone slopes, in particular to a water-retaining mixed agent soil prepared from biogas fermentation residues and a method thereof.

Background technique

With the growth of population and the continuous deterioration of ecological environment, the land resources available for human use are decreasing day by day. In recent years, due to the reclamation of wasteland, the destruction of forests, the predatory development of mineral resources, and the high-speed development of transportation, energy, communications and other industries, a large area of land surface has been disturbed, resulting in land destruction and new soil erosion, and the area of soil erosion has increased. reduce. Experts predict that if no attention is paid, the increasing soil erosion will inevitably affect the sustainable development of social economy and directly threaten the ecological security of the country. The vigorous development of highway construction has caused the amount of water and soil loss to account for a large proportion of the total amount of water and soil loss. At present, it has become one of the most serious national soil and water losses in my country. The degree of damage is worrying. Decreased soil fertility, silt deposits, and weakened flood control capabilities. Facing such a severe situation, how to take effective measures to reduce the degree of soil erosion and promote the rational use of existing land resources is imminent.

Using biogas fermentation residues, especially biogas residue and biogas slurry, to prepare slope greening and water-retaining mixed soil is an effective way to solve the above problems. Biogas fermentation residue biogas residue and biogas slurry are used as the main raw materials for preparation, and its sources are very extensive, which can be used for the comprehensive development and utilization of biogas residue and biogas slurry, and realize the "three transformations" of solid waste (recycling, reduction, and harmlessness) provide an effective way. In our country, biogas digesters are being constructed and applied on a large scale in rural areas and other areas. But what follows is that more and more biogas fermentation residues are produced. If they are not effectively comprehensively utilized and resourced, the biogas fermentation residues will become solid waste and cause harm to the environment. Biogas fermentation residues have been determined to be rich in humic acid, organic matter, total nitrogen, phosphorus, total potassium and available nitrogen, phosphorus, potassium and other components required for crop growth and development. The anaerobic fermentation biogas production process consumes carbon and hydrogen in the fermentation raw materials, that is, 1 C atom and 4 H atoms combine to form a CH ₄ molecule, so the nitrogen, phosphorus, and potassium residues of biogas fermentation are beneficial to plants. The nutrients for growth are not lost. At the same time, after anaerobic fermentation treatment, nitrogen, phosphorus, potassium and other components exist in a more usable form for absorption. For example, the amount of ammonium nitrogen (that is, available nitrogen) is more than doubled. It is more conducive to the needs of crops for nitrogen nutrition, and the total nitrogen loss is only 1.1%. Therefore, using biogas slurry and residue as raw materials, the composite mixed soil prepared has higher nutrients than ordinary soil.

Contents of the invention

The purpose of the present invention is to provide a kind of compound soil with high efficiency and high water retention and low cost, which has both slow and fast nutritional components, fertilizer retention, water retention, light load, not easy to harden, and low cost, which can prevent soil erosion and beautify the environment. Through the following technologies The plan is realized.

A method for preparing water-retaining mixed soil with biogas fermentation residue, through the following steps:

Mix biogas residue, sawdust, bone meal, and soil, grind them, then add swollen water-retaining agent to the mixture, then add biogas slurry and stir evenly, and place it in normal temperature for anaerobic fermentation for 20 to 30 days to obtain biogas fermentation residue Prepared water-retaining mixture soil.

The water-retaining agent is a starch-grafted acrylic acid-type water-retaining agent.

The biogas residue, sawdust, bone meal, soil, and water-retaining agent are mixed according to the following mass percentages: 35% biogas residue, 18% sawdust, 5.5% bone meal, 40% soil, and 1.5% water-retaining agent.

The biogas slurry added is 300mL per kilogram of mixture.

The crushed particle size is less than 3mm.

The biogas residue is a solid-phase air-dried residue of biogas fermentation that has produced gas for more than 60 days.

The raw material for the biogas fermentation is human and livestock manure and/or crop straw.

Another object of the present invention is to provide a water-retaining soil mixture prepared from biogas fermentation residue, which is the water-retaining soil mixture obtained by the above method.

Biogas residue, one of the raw materials used in the present invention, has comprehensive nutritional components, including organic matter, total nitrogen, total phosphorus, total potassium, rate nitrogen, available phosphorus, and available potassium. The fiber organic matter of biogas residue has large porosity, many pores, strong ion exchange and strong water absorption capacity. Sawdust can loosen the soil, increase ventilation, water permeability and water retention. At the same time, it has strong thermal insulation and can reduce the temperature difference between day and night of the mixed soil, so it can be used to promote the growth of plants. The application of water-retaining agent can not only fully absorb irrigation water or natural rainfall, prevent water leakage and loss, improve water use efficiency, but also promote the formation of soil aggregates, improve soil pore structure, prevent fertilizers, pesticides and soil erosion, and improve effective use of fertilizers. The biogas slurry is rich in trace elements, humic acid, amino acids, plant growth hormones, and antibiotics, which can promote plant growth and strengthen plant resistance to diseases and insect pests. It is mixed with dry substrate and anaerobically fermented to increase the nutrients in the water-retaining mixture soil. .

Adding an appropriate amount of starch-grafted acrylic water-retaining agent to the mixed soil aims to strengthen the moisturizing effect of the compound mixed soil. The starch-grafted type is a high-molecular polymer with high water absorption. It contains a large number of strong water-absorbing groups with specific structures. The parameters have been improved, and it is mainly used for water storage and moisture conservation in afforestation land. It has a long service life, excellent properties such as water absorption rate and water absorption speed, and low cost. In order to ensure the growth of green plants such as green grass and flowers planted on the mixed soil, an appropriate amount of bone meal is also added to the mixed soil to increase the ratio of calcium and phosphorus in the soil. Bone meal is a white powder, which can be used as base fertilizer and applied after fermentation to improve fertilizer efficiency. The present invention also improves the utilization degree of nutrients in the biogas slurry and biogas residue by the crops by anaerobic fermentation of the water-retaining mixed agent soil, according to the effective components such as nitrogen, phosphorus, and potassium required by the material and the required content of the mixed agent soil. The required porosity and density can be adjusted by adding appropriate biogas slurry to prepare a composite high-efficiency water-retaining mixed soil.

The invention provides a composite high-efficiency water-retaining mixed soil, which uses biogas fermentation residue biogas residue and biogas slurry as main raw materials and is suitable for slope greening. It is characterized by good water retention effect, low water and soil loss, and comprehensive nutritional components. The stable release of effective nutrients and low cost are especially suitable for slope greening on high-efficiency roads and other places, and can also be used as substrate soil for roofs, gardens or potted plants. The use of mixed soil for greening can beautify the landscape environment of the side slopes of the expressway and other places, improve the quality of the ecological environment, and have both ecological effects, economic effects and social effects. The present invention has the following advantages:

1. The cost is low, and the present high-efficiency water-retaining compound soil mix uses waste as most of the raw materials, and the manufacturing process is simple and the investment is small.

2. It can quickly absorb rainwater and irrigation water and store it, and release it slowly when plants need it, which can not only ensure the water needed for normal growth of plants, but also prevent water from being wasted due to evaporation, leakage, and loss, ensuring The soil keeps moist for a long time, and can absorb and release water repeatedly, and slowly supply it to plants.

3. Nutrients are comprehensive, with both slow-acting and quick-acting nutrients.

4. Improve soil structure (aggregate structure, water permeability, air permeability). Repeated shrinkage and imbibition creates a large number of pores in the soil, improves the air permeability and water permeability of the soil, improves the rhizosphere environment, and also enhances the activities of rhizosphere microorganisms, and accelerates the decomposition of organic minerals around the rhizosphere. It is conducive to root absorption, promotes the growth and development of roots and plants, improves the soil matrix, and prevents soil compaction and salinization.

5. It has a wide range of applications, and can maintain its stability and high efficiency under different climatic conditions, dust suppression and corrosion protection. It can be used for greening and potted flower plants on slopes, roofs and courtyards.

6. If the fertilizer is mixed with it, the fertilizer can be stored and released slowly while storing rainwater and irrigation water, reducing the fertilizer and waste caused by evaporation and leakage, thereby improving the utilization rate of the fertilizer.

7. The preparation materials used are all harmless substances, which do not produce toxic and side effects on planted crops, and the use process has no pollution to the environment.

Description of drawings

Fig. 1 is the comparison of soil moisture evaporation between water-retaining mixture soil and common soil quality;

Fig. 2 is the soil water evaporation rate comparison of water-retaining mixture soil and common soil quality;

Figure 3 is a comparison of soil water and soil loss between water-retaining mixture soil and ordinary soil.

Detailed ways

Example 1

Mix 3.5kg of biogas residue, 1.8kg of sawdust, 0.55kg of bone meal, and 4kg of soil, and crush them until the particle size is less than 3mm. Dry matter, then take 0.15 kg of starch-grafted acrylic acid type water-retaining agent to be swollen, add it to the mixture, then add 3000 mL of biogas slurry and stir evenly, and place it in normal temperature for 20 days after anaerobic fermentation to obtain a water-retaining mixture prepared from biogas fermentation residue earth.

The mass percentage of each component in the obtained water-retaining mixed agent soil is as follows: 35% biogas residue, 18% sawdust, 5.5% bone meal, 40% soil, 1.5% starch-grafted acrylic water-retaining agent, and 3000mL biogas slurry.

Example 2

Mix 3.5kg of biogas residue, 1.8kg of sawdust, 0.55kg of bone meal, and 4kg of soil, and crush until the particle size is less than 3mm. The biogas residue is the solid-phase air-dried residue of biogas fermentation of human and animal manure that has produced gas for more than 60 days, and then Take 0.15 kg of starch-grafted acrylic acid-type water-retaining agent and add it to the mixture after swelling, then add 3000 mL of biogas slurry and stir evenly. After 30 days of anaerobic fermentation at room temperature, a water-retaining mixture soil prepared from biogas fermentation residues is obtained.

The mass percentage of each component in the obtained water-retaining mixed agent soil is as follows: 35% biogas residue, 18% sawdust, 5.5% bone meal, 40% soil, 1.5% starch-grafted acrylic water-retaining agent, and 3000mL biogas slurry.

Example 3

Mix 3.5kg of biogas residue, 1.8kg of sawdust, 0.55kg of bone meal, and 4kg of soil, and crush until the particle size is less than 3mm. The biogas residue is the solid-phase air-dried residue of biogas fermentation of crop straw that has produced gas for more than 60 days, and then Take 0.15 kg of starch-grafted acrylic acid type water-retaining agent and add it to the mixture after swelling, then add 3000 mL of biogas slurry and stir evenly, and place it in room temperature for anaerobic fermentation for 25 days to obtain a water-retaining mixture soil prepared from biogas fermentation residues.

The mass percentage of each component in the obtained water-retaining mixed agent soil is as follows: 35% biogas residue, 18% sawdust, 5.5% bone meal, 40% soil, 1.5% starch-grafted acrylic water-retaining agent, and 3000mL biogas slurry.

The compound fertilizer-preserving mixed agent soil that adopts embodiment 1 gained carries out physical and chemical characteristic parameter analysis, see table 1:

Table 1 Analysis of physical and chemical characteristic parameters of slope greening and water-retaining mixture soil

Dry the mixed soil in the shade, remove thick roots and small stones, analyze its specific gravity, bulk density, porosity and pH value, and compare it with the corresponding indicators of ordinary soil samples. The results show that the pH of the mixed soil does not change significantly due to the addition of water-retaining agent and biogas residue. After adding water-retaining agent, biogas slurry, biogas residue and other effective components to the mixed soil, the bulk density decreased slightly, while the specific gravity and porosity increased significantly. The main reason for the increase in porosity is that the biogas residue contains cellulose, hemicellulose and lignin, which can increase the porosity of the mixed soil, thus effectively improving the physical and chemical properties of the soil.

The slope greening and water-retaining mixed soil obtained in Example 2 was used for plant growth analysis and mixed soil composition analysis, as shown in Table 2.

Table 2 Analysis of nutrient components of slope greening water retention

The measurement results showed that the content of nutrient components in the mixture soil was higher than that of the control common soil soil sample. Aster was selected as the test plant to investigate the growth of crops in the slope greening and water-retaining mixed soil, and the common soil was used as the reference soil sample to compare the seed germination rate, average plant height, and Crown diameter, number of leaves, average leaf length and average leaf width and other indicators. Three months after planting, the content of each nutrient component in the mixed soil was determined. After comparative analysis, the seed germination rate, average plant height, crown diameter, average leaf length, average leaf width, and number of leaves of aster in the mixed soil were 36.54%, 4.43 cm, 0.73 cm, 1.03 cm, 0.22 cm and 3 pieces. From the comparison of the growth of aster in mixed soil and ordinary soil, it can be seen that the water-retaining mixed soil for slope greening is beneficial to the growth of crops due to the improvement of soil physical and chemical indicators. Compared with ordinary soil soil, the content of organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus and available potassium nitrogen in the mixed soil is significantly increased, and available phosphorus, available nitrogen and available potassium are extremely needed for crop growth Nutrients, so the mixed soil is more conducive to the growth of crops.

The comparative analysis of soil water evaporation and water evaporation rate between the slope greening and water-retaining mixed soil obtained in Example 3 and common soil quality soil is shown in Fig. 1 and Fig. 2 .

The results showed that the water evaporation of the two soils showed a trend of first increasing and then decreasing with the prolongation of the drought stress time. In the first three days of drought stress, the water evaporation of the two soils increased rapidly. After that, the water evaporation of the two soil samples The water evaporation all began to show a downward trend. During this period, the water evaporation of the two soils was significantly different. The water evaporation of the control was significantly higher than that of the soil treated with the water-retaining agent. The ordinary soil without adding the water-retaining agent lost a total of 44.87g/ cm ² , while the soil added with water-retaining agent lost a total of 33.642 g/cm ² of water, which was 14.19% lower than the water evaporation rate of the control soil sample, indicating that the application of water-retaining agent can effectively inhibit the evaporation of soil water. The reduction of water loss and the reduction of water evaporation rate show that the slope greening water-retaining mixture soil has a stronger water-retaining capacity than ordinary soil.

The slope greening and water-retaining mixed soil obtained in Example 3 and the ordinary soil were used to analyze the amount of soil loss, and the specific results are shown in Figure 3. the

Cover the mixed soil on the slope with a slope of 40° to make an artificial simulated slope, measure the amount of soil loss after each rainfall, and compare it with ordinary soil. The results showed that the average soil loss of the mixed soil decreased by 68.40 g/m ² , which indicated that the slope greening and water-retaining mixed soil could effectively reduce the amount of water and soil loss.

Claims (7)

1. A method for preparing water-retaining mixed agent soil with biogas fermentation residue, is characterized in that through the following steps: Mix biogas residue, sawdust, bone meal, and soil, grind them, then add swollen water-retaining agent to the mixture, then add biogas slurry and stir evenly, and place it in normal temperature for anaerobic fermentation for 20 to 30 days to obtain biogas fermentation residue Prepared water-retaining mixed agent soil; wherein, biogas residue, sawdust, bone meal, soil, and water-retaining agent dry agent are mixed according to the following mass percentages: biogas residue 35%, sawdust 18%, bone meal 5.5%, soil 40%, water-retaining agent 1.5%. 2. The method according to claim 1, characterized in that: the water retaining agent is a starch grafted acrylic acid type water retaining agent. 3. The method according to claim 1 or 2, characterized in that: the added biogas slurry is 300 mL per kilogram of the mixture of biogas residue, sawdust, bone meal, soil, and water-retaining agent. 4. The method according to claim 1 or 2, characterized in that: the particle size of the pulverization is less than 3mm. 5. The method according to claim 1 or 2, characterized in that: the biogas residue is a solid-phase air-dried residue of biogas fermentation that has produced gas for more than 60 days. 6. The method according to claim 5, characterized in that: the raw materials for the biogas fermentation are human and livestock manure and/or crop straw. 7. A water-retaining mixed soil obtained by any one of the methods of claims 1-6.

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