CN112239270B

CN112239270B - Novel material capable of being used as plant planting matrix, preparation method and application thereof

Info

Publication number: CN112239270B
Application number: CN202011036476.2A
Authority: CN
Inventors: 许晓光; 史宸菲; 李丛杨; 陈赟; 程一; 王国祥
Original assignee: Nanjing Normal University
Current assignee: Nanjing Normal University
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2022-09-13
Anticipated expiration: 2040-09-28
Also published as: CN112239270A

Abstract

The invention belongs to the field of river and lake pollution treatment, and particularly relates to a novel material capable of being used as a plant planting matrix, and a preparation method and application thereof. The blue algae and the bottom mud are mixed according to a certain proportion and then fermented, and the fermentation product is used as a raw material for preparing a novel material, and the prepared material has low C/N and can be used as a filler of a fine matrix layer or a planting matrix of soil plants after being mixed with soil. The invention is beneficial to the growth of microorganisms in the artificial wetland, the microorganisms can mineralize complex nitrogen-containing organic matters and convert the nitrogen-containing organic matters into inorganic nitrogen compounds which can be directly utilized by plants and microorganisms, thereby promoting the growth of the plants, and the invention can also recover a large amount of biomass energy from blue algae with the highest efficiency and can also carry out harmless treatment on bottom mud to the greatest extent.

Description

Novel material capable of being used as plant planting matrix, preparation method and application thereof

Technical Field

The invention belongs to the field of river and lake pollution treatment, and particularly relates to a novel material capable of being used as a plant planting matrix, and a preparation method and application thereof.

Background

The substrate cultivation technology has become a soilless cultivation technology with the widest application because of the advantages of safety, sanitation, high product quality, controllable plant growth and the like. When the plant cultivation substrate is selected, firstly, the material is easy to obtain, the price is low, the chemical characteristics are good, the nutrition is comprehensive, the water and fertilizer retention capacity is strong, and the requirements of the growth and development of the cultivated plant can be met for a long time; secondly, the matrix is required to have good physical properties, low density and good structure and permeability; the pH value of the substrate is moderate, and the optimum pH value of most plant culture substrates is adjusted to be 5.5-7.5; in addition, the substrate is required to be free of impurities, insect pests, germs and peculiar smell.

At present, most of plant culture media applied at home and abroad are mainly peat products. However, since peat fields are atmospheric carbon dioxide gathering systems which have great effects on reducing atmospheric carbon dioxide concentration and reducing greenhouse effect, excessive peat mining inevitably affects global climate change. In addition, peat swamps are important ecological wetlands, and the exploitation of peat tends to destroy the ecological environment of biological species on which the species live. In order to avoid the deterioration of the whole ecology, many countries have started to limit the use of peat development, the price of peat-based plant culture media is high, and the development of peat substitutes or the direct use of other organic materials as culture media has become the future development direction.

The biochar is a highly aromatic infusible solid substance generated by pyrolyzing and carbonizing a biomass material under the condition of complete or partial oxygen deficiency, has super strong fertilizer retention capacity, and can reduce the loss of nutrients; also contains some nutrient elements required by plant growth, and also has promoting effect on plant growth. In addition, the biochar is used as a plant planting matrix and plays an important role in removing nitrogen and phosphorus in water, organic pollutants, beautifying the environment and the like. Therefore, the biochar as the substrate has good application prospect and significance in soilless culture agriculture.

The invention patent with the application number of CN 106630156A and the publication number of 2017, 5 and 10 discloses a system for strengthening the sewage treatment effect of an artificial wetland, which comprises a water inlet system, a water inlet biochar filter tank, a wetland substrate, wetland plants and a water outlet system, wherein activated biochar is filled in the biochar filter tank, the wetland plants are planted on the wetland substrate, and the wetland substrate consists of the artificial wetland substrate and the activated biochar; the preparation process of the activated charcoal comprises the following steps: 1) drying and crushing the harvested wetland plants in sequence; 2) sequentially drying and crushing the artificial wetland substrate; 3) fully mixing the crushed wetland plants and the artificial wetland substrate according to the mass ratio of 3-5:1 to obtain a mixture; 4) pyrolyzing the mixture at high temperature under an anoxic condition to obtain biochar; 5) and (3) activating the biochar by acid to obtain activated biochar. The biochar obtained in the prior art can be used as an adsorbent with good performance, can fix heavy metals in the environment, and can influence plant growth when the content of the heavy metals in the biochar is too high. Meanwhile, the preparation cost of the biochar is high, the economic benefit is poor after industrialization, and the application range is narrow.

Disclosure of Invention

1. Problems to be solved

Aiming at the problem of poor planting effect of the plant planting matrix in the prior art, the invention provides a novel material capable of being used as the plant planting matrix, the C/N of the novel material is low, the novel material is beneficial to the growth of microorganisms in the artificial wetland, the microorganisms can mineralize complex nitrogen-containing organic matters and convert the nitrogen-containing organic matters into inorganic nitrogen compounds which can be directly utilized by plants and microorganisms, the growth of the plants is further promoted, and the problem of poor planting effect of the planting matrix in the prior art is solved.

Furthermore, the invention provides a method for preparing plant planting matrix by using blue algae and bottom mud, which comprises the steps of mixing the blue algae and the bottom mud according to a certain proportion, fermenting, and taking a fermentation product as a raw material for preparing the novel material, so that a large amount of biomass energy can be recovered from the blue algae with the highest efficiency, simultaneously, the bottom mud can be subjected to harmless treatment to the greatest amount, and the yield of the prepared novel material is high.

Furthermore, the invention also provides an artificial wetland plant planting unit, the novel material of the invention is used as the filler of the fine matrix layer, the capacity of traditional filler for adsorbing pollutants can be exerted, and the artificial wetland plant planting unit can also be used as a slow release system of phosphate, can adsorb phosphate when the phosphorus content of a water body is high, slowly releases phosphorus when submerged plants grow and need the phosphate, and greatly ensures the stability of water ecology.

Furthermore, the invention can be mixed with soil to be used as a planting substrate of soil plants, is simple to use and low in raw material cost, and can provide nutrient substances for the plants and promote the growth of the plants.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention provides a novel material which can be used as a plant planting substrate and has a specific surface area of 5.8-18.0m ² In terms of a/g ratio of the mass content of C to the mass content of N is 3.9 to 16.

Preferably, the C content is 1% to 1.7%; the content of N is 0.1-0.3%.

The invention also provides a method for preparing the plant planting matrix by using the blue algae and the bottom mud, which comprises the steps of mixing and fermenting the blue algae and the bottom mud to obtain fermented mud, and firing the fermented mud to obtain the novel material; the total volatile solid content in the blue algae is m, the total volatile solid content in the bottom mud is n, and m: n is 1:4-4:1 in the mixture after the blue algae and the bottom mud are mixed.

Preferably, the bottom mud is modified bottom mud, the modification mode is to stir the bottom mud from bottom to top, and the bottom mud is pre-fermented for 7-10 days after stirring.

Preferably, the fermentation time of the mixed anaerobic fermentation of the blue algae and the bottom mud is 15-35 d.

Preferably, the firing temperature used when firing the fermentation sludge is 350 ℃ to 550 ℃.

Preferably, the yield of the novel material is greater than 90%.

Preferably, the substrate sludge is at least one of algae type substrate sludge and grass type substrate sludge.

The invention also provides an artificial wetland plant planting unit which comprises a plant layer, a thin matrix layer and at least one thick matrix layer which are arranged from top to bottom, wherein the novel material is used as a filler in the thin matrix layer.

The invention also provides an application of the novel material mixed with soil as a planting matrix of soil plants.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) the novel material can be used as a plant planting matrix, has low C/N, is beneficial to the growth of microorganisms, and can mineralize complex nitrogen-containing organic matters by the microorganisms to convert the complex nitrogen-containing organic matters into inorganic nitrogen compounds which can be directly utilized by plants and microorganisms; the low carbon-nitrogen ratio is particularly suitable for the growth of fungi, the fungi can promote the decomposition of cellulose, lignin, pectin and the like, and can finally decompose protein to release ammonia suitable for plants to promote the growth of the plants, thereby solving the problem of poor planting effect of the planting matrix in the prior art.

(2) The novel material used as the plant planting matrix has the N content of 0.1-0.3%, the low-N porous material is beneficial to the growth of gram-negative bacteria, and the gram-negative bacteria serving as dominant species in the constructed wetland can promote the decomposition of macromolecular substances and cooperate with the growth of plants.

(3) According to the method for preparing the plant planting substrate by using the blue algae and the bottom mud, the mixing ratio of the blue algae and the bottom mud is controlled to be 1:4-4:1(VS), fermentation is performed, and then fermented mud is used as a raw material for preparation, so that a large amount of biomass energy can be recovered from the blue algae at the highest efficiency, meanwhile, the bottom mud can be subjected to harmless treatment at the highest rate, and the problem of poor treatment effect of the polluted bottom mud and the blue algae is solved.

(4) According to the method for preparing the plant planting matrix by using the blue algae and the bottom mud, the used bottom mud is the modified bottom mud, the modified bottom mud has good chemical buffering capacity, the acidification of an anaerobic reaction system can be prevented, and the utilization degree of the blue algae and the bottom mud is maximized.

(5) According to the method for preparing the plant planting matrix by using the blue algae and the bottom mud, when the firing temperature is too low, the strength of the obtained product is low; when the firing temperature is too high, organic matters which are contained in the biogas residues and can be utilized by plants are excessively removed, and the obtained product has strong adsorption force and is easy to enrich heavy metals, thereby generating toxic action on the plants.

(6) The novel material is used as a substrate layer of aquatic plants planted in the artificial wetland, organic matters which are difficult to be biologically utilized in biogas residues can be further utilized by preparing the novel material by taking fermented biogas residues as a raw material, and the novel material becomes a tighter adsorption carrier of phosphorus-containing inorganic salts in the biogas residues, so that the capability of the traditional novel material for adsorbing pollutants can be exerted, meanwhile, the novel material can be used as a slow release system of phosphate, the phosphate is adsorbed when the water body has high phosphorus content, and the phosphorus is slowly released when the submerged plants grow and need the phosphate.

Drawings

FIG. 1 is a graph of the total nitrogen concentration of the overlying water during a release test of the present invention;

FIG. 2 is a graph showing the ammonia nitrogen concentration change of the supernatant water during the release test according to the present invention;

FIG. 3 is a schematic view of a release test apparatus of the present invention;

FIG. 4 is a schematic structural view of the device when the device is applied to a substrate layer of an artificial wetland;

in the figure:

100. an aquatic plant; 200. an upper substrate layer; 300. a lower matrix layer.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The invention is described in detail below with reference to specific exemplary embodiments. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description and drawings are to be regarded as illustrative rather than restrictive, and any such modifications and variations are intended to be included within the scope of the present invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.

Example 1

The invention provides a novel material which can be used as a plant planting substrate and has the specific surface area of 5.8-18.0m ² (iv)/g, and the ratio of the mass content of C to the mass content of N of the material is 3.9 to 16. Further explaining, the mass content of C is 1.0-1.7%; the mass content of N is 0.1-0.3%.

The novel material has low C/N, is beneficial to the growth of microorganisms, and the microorganisms can mineralize complex nitrogen-containing organic matters and convert the nitrogen-containing organic matters into inorganic nitrogen compounds which can be directly utilized by plants and microorganisms. The low carbon nitrogen ratio is particularly suitable for fungal growth, the fungi can promote the decomposition of cellulose, lignin, pectin and the like, and can finally decompose protein to release ammonia suitable for plants to promote the growth of the plants, thereby solving the problem of poor planting effect of the planting matrix in the prior art. Moreover, the low-N porous material is beneficial to the growth of gram-negative bacteria, and the gram-negative bacteria serving as dominant species in the constructed wetland can promote the decomposition of macromolecular substances and cooperate with the growth of plants.

The invention also provides a method for preparing the novel material by using the blue algae and the bottom mud, and the novel material is obtained by mixing and fermenting the blue algae and the bottom mud to obtain fermented mud residue and then firing the fermented mud residue. The bottom mud used by the invention is grass type bottom mud or algae type bottom mud, and both the bottom mud and the bottom mud contain extremely rich microbial communities and organic matters which are easy to utilize in the microbial growth process. The mass ratio of Volatile Solids (VS) in the grass-type bottom mud in the wet weight of the mixture is 2-3%. The grass type bottom mud is sediment in a water area with a clear water body and a large amount of aquatic plants growing, is mainly generated by aquatic plant decay and deposition, the total organic carbon content of the grass type bottom mud is 18.5-28.5mg/kg, and the mass ratio of short-chain organic matters in the total organic carbon is more than 22%. And in the algae-type sediment, the mass ratio of VS is more than 3%. The algae-type sediment is the sediment of a water area where a large amount of blue algae are accumulated and almost no waterweeds grow and is mainly generated by blue algae decay deposition, the total organic carbon content of the algae-type sediment is 16.5-18.5mg/kg, and the mass percentage of short-chain organic matters in the total organic carbon is more than 35%.

Before the bottom mud and the blue algae are mixed, the bottom mud is modified in a mode that the bottom mud is stirred from bottom to top, and after stirring, anaerobic fermentation is carried out for 7-10 days at the temperature of about 35 ℃. The natural laminar distribution of anaerobic microorganisms in the sediment can be changed by the stirring mode from top to bottom, so that the microorganisms in the sediment are uniformly distributed, and the synchronous implementation of the domestication process is facilitated. The pre-fermentation can also release part of the stable humus in the bottom mud, so that the bottom mud is favorable for combining the heavy metal released by the blue algae fermentation. Moreover, under the action of the humus reducing bacteria, partial humus in the bottom sediment is reduced, the process can synchronously stabilize free heavy metal existing in the bottom sediment, and the bioavailability of the heavy metal contained in the prepared novel material is reduced.

The preparation method comprises the following specific preparation steps:

s100, filtering and mixing the blue algae and the bottom mud to obtain an algae mud mixture, wherein the VS mixing ratio during mixing is that the blue algae is 1:4-4: 1;

s200, placing the algae mud mixture into a reactor, introducing nitrogen, sealing, reacting for 15-35d, and filtering to obtain fermentation mud residues and fermentation liquor;

s300, firing the fermentation sludge to obtain a novel material, wherein the firing temperature is 350-550 ℃, and the firing time is 1 h; because the organic matters in the sludge are decomposed basically by the pretreatment of the previous fermentation, the yield of the novel material prepared by the preparation method is more than 90 percent.

The invention also provides an application example of the novel material in the artificial wetland, and the novel material is used as a substrate of aquatic plants planted in the artificial wetland. The artificial wetland plant planting unit comprises a plant layer, a fine matrix layer and at least one coarse matrix layer which are arranged from top to bottom, wherein in the filler used by the fine matrix layer, the mass ratio of the novel material is at least 15%. It is worth mentioning that the fine matrix layer comprises a novel material layer and a sediment layer arranged from top to bottom, wherein the sediment layer may use at least one of soil, bottom mud or sludge. It is worth to say that the invention can be mixed with soil to be used as a planting substrate of soil plants, and the microbial abundance in the soil can be effectively improved.

In the embodiment, the blue algae and the bottom mud are mixed to prepare the novel material, the specific preparation steps are as follows,

s100, filtering the blue algae and the bottom mud, wherein the VS mixing ratio during mixing is that the blue algae: 1:4 of bottom mud; it is worth to be noted that when the ratio of the blue algae to the bottom mud VS is 1:4, the fermentation is balanced most quickly; the mixture has the highest SCOD removal rate, namely the highest bioenergy conversion efficiency;

s200, placing the algae mud mixture into a reactor, introducing nitrogen, sealing, reacting for 15d at 40 ℃, and filtering to obtain fermentation mud residues and fermentation liquor;

s300, firing the fermentation sludge to obtain a novel material, wherein the firing temperature is 350 ℃, the firing time is 1h, and the specific surface area and the pore volume of the prepared novel material are shown in Table 1, wherein C350 refers to the novel material prepared from the mixed fermentation product of the blue algae and the grass-type bottom sludge, and Z350 refers to the novel material prepared from the mixed fermentation product of the blue algae and the grass-type bottom sludge. The yield of the novel material and the elemental analysis are shown in table 2.

TABLE 1 specific surface area and pore volume of the novel materials

TABLE 2 yield and elemental analysis of novel materials

In this embodiment, emergent aquatic plants or submerged plants are planted in the plant purification units, as shown in fig. 4, the plant purification units in the artificial wetland comprise aquatic plants 100, an upper substrate layer 200 and a lower substrate layer 300, the upper substrate layer 200 generally consists of substrate particles with smaller particle size, and the mass of the novel material of the invention accounts for 35% of the total mass of the filler of the upper substrate layer 200. The lower matrix layer 300 is generally composed of particulate matter having a relatively large particle size, such as zeolite, ceramic particles, and the like.

Further, when the present invention is used for a nutrient release test, the apparatus is shown in fig. 3, and the apparatus is provided with the upper water, the novel material of the present invention and the bottom mud from top to bottom. As shown in figures 1 and 2, the total nitrogen and ammonia nitrogen contents in the column of the grass type sludge (C350) and the algae type sludge (Z350) which are fired at 350 ℃ are obviously higher than those in the blank columns (K1 and K2) without adding the novel material, the material releases part of nutrients, and pollutants in the bottom sludge can be slowly released into the water body to be utilized by plants.

Example 2

The basic content of this example is the same as example 1, except that the novel material was prepared in the following steps,

s100, filtering and mixing the blue algae and the bottom mud to obtain an algae mud mixture, wherein the VS mixing ratio during mixing is that of the blue algae: 1:1 of bottom mud;

s200, placing the algae mud mixture into a reactor, introducing nitrogen, sealing, reacting for 30d at 35 ℃, and filtering to obtain fermentation mud residues and fermentation liquor;

s300, firing the fermentation sludge to obtain the novel material, wherein the firing temperature is 500 ℃, the firing time is 1h, and the parameters of the prepared novel material are similar to those of example 1, but the nitrogen content in the overlying water is slightly lower than that of example 1, possibly caused by lower organic matter content in the material.

Example 3

The basic content of this example is the same as that of example 1, except that the blue algae and the bottom mud are filtered and mixed to obtain an algae mud mixture, and the VS mixing ratio during mixing is the blue algae: bottom mud is 4: 1; the parameters of the prepared novel material are similar to those of example 1, but the nitrogen content in the overlying water is slightly lower than that in example 1, which is probably caused by rapid decomposition of blue algae and low organic matter content in sludge.

Example 4

The basic content of this example is the same as example 1, except that the specific preparation steps of this example are as follows,

s100, filtering the blue algae and the bottom mud to obtain an algae mud mixture, wherein the VS mixing ratio during mixing is that of the blue algae: 1:4 of bottom mud;

s200, placing the algae mud mixture into a reactor, introducing nitrogen, sealing, reacting for 35d at 35 ℃, and filtering to obtain fermentation mud residues and fermentation liquor;

s300, firing the fermentation sludge to obtain the novel material, wherein the firing temperature is 550 ℃, the firing time is 1h, the specific surface area and the pore volume of the prepared novel material are shown in a table 3, and the yield and the element analysis of the novel material are shown in a table 4.

TABLE 3 specific surface area and pore volume of the novel materials

TABLE 4 yield of novel materials and elemental analysis

Further, when the present invention is used for a nutrient release test, as shown in fig. 1 and fig. 2, the total nitrogen and ammonia nitrogen content in the column of the grass-type sludge (C550) and the algae-type sludge (Z550) fired at 550 ℃ is similar to that of the blank column (K1, K2) without adding the new material, which may be because the firing temperature is high, the adsorption capacity of the obtained adsorption material is strong, so that the nitrogen in the bottom sludge is adsorbed in the new material, and therefore, the firing temperature needs to be controlled below 550 ℃ when firing the new material of the present invention.

More specifically, although exemplary embodiments of the invention have been described herein, the invention is not limited to these embodiments, but includes any and all embodiments modified, omitted, combined, e.g., between various embodiments, adapted and/or substituted, as would be recognized by those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly based the language employed in the claims and not limited to examples described in the foregoing detailed description or during the prosecution of the application, which examples are to be construed as non-exclusive. Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. The scope of the invention should, therefore, be determined only by the appended claims and their legal equivalents, rather than by the descriptions and examples given above.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. When a "mass, concentration, temperature, time, or other value or parameter is expressed as a range, preferred range, or as a range defined by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, a range of 1 to 50 should be understood to include any number, combination of numbers, or subranges selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, and all fractional values between the above integers, e.g., 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, specifically consider "nested sub-ranges" that extend from any endpoint within the range. For example, nested sub-ranges of exemplary ranges 1-50 may include 1-10, 1-20, 1-30, and 1-40 in one direction, or 50-40, 50-30, 50-20, and 50-10 in another direction. "

Claims

1. A method for preparing plant planting matrix by using blue algae and bottom mud is characterized by comprising the following steps: mixing blue algae and bottom mud for fermentation to obtain fermentation sludge, and firing the fermentation sludge to obtain a planting matrix; the total volatile solid content in the blue algae is m, the total volatile solid content in the bottom mud is n, and m: n is 1:4-4:1 in a mixture formed by mixing the blue algae and the bottom mud; the firing temperature used when firing the fermentation sludge is 350-550 ℃;

the specific surface area of the planting substrate is 5.8-18.0m ² The planting substrate comprises a planting substrate body, wherein the planting substrate body comprises a C content and an N content, the C content and the N content are in a ratio of 3.9-16, 1.0-1.7% and 0.1-0.3%, respectively.

2. The method for preparing the plant planting substrate by utilizing the blue algae and the bottom mud as claimed in claim 1, wherein the method comprises the following steps: the bottom mud is modified bottom mud, the modification mode is that the bottom mud is stirred from bottom to top, and the bottom mud is pre-fermented for 7-10 days after being stirred.

3. The method for preparing the plant planting substrate by utilizing the blue algae and the bottom mud as claimed in claim 1, wherein the method comprises the following steps: the fermentation time of the mixed anaerobic fermentation of the blue algae and the bottom mud is 15-35 d.

4. The method for preparing the plant planting substrate by utilizing the blue algae and the bottom mud as claimed in claim 1, wherein the method comprises the following steps: the yield of the planting substrate is more than 90%.

5. The method for preparing the plant planting substrate by using the blue algae and the bottom mud as claimed in claim 1, wherein the method comprises the following steps: the bottom mud is at least one of algae type bottom mud and grass type bottom mud.

6. The utility model provides an artificial wetland plant species plants unit, includes plant layer, thin matrix layer and at least one thick matrix layer that from top to bottom sets up, its characterized in that: the filler used in the fine matrix layer includes the planting matrix prepared by the preparation method of any one of claims 1 to 5.

7. Use of a planting base prepared by the method according to any one of claims 1 to 5 as a planting base for soil plants after mixing with soil.