CN115650439A - Constructed wetland matrix prepared from water purification sludge and preparation method thereof - Google Patents

Abstract

The invention relates to an artificial wetland substrate prepared by utilizing water purification sludge and a method thereof, and belongs to the technical field of sludge reuse. The present invention takes the water purification sludge from the water supply plant as the original, firstly calcines and pre-treats it with acid leaching, then mixes and sinters it with bentonite to form a matrix matrix, collects blue-green algae and crushes them, adds ferric chloride and press-filters to obtain blue-green algae compressed The filtrate is finally compounded with the cyanobacteria press filtrate and the matrix matrix to finally prepare the artificial wetland matrix, which has excellent adsorption and permeability, and has broad application prospects.

Description

Constructed wetland matrix prepared from water purification sludge and preparation method thereof

technical field

The invention relates to an artificial wetland substrate prepared by utilizing water purification sludge and a method thereof, and belongs to the technical field of sludge reuse.

Background technique

At present, water resource shortage and water environment pollution are two important problems facing my country's water environment, especially for rural areas with weak economic strength and poor infrastructure construction, a large amount of untreated domestic sewage is directly discharged into various water bodies, causing serious pollution. Water ecological environment, sewage treatment is imminent. Constructed wetlands have the advantages of low investment, simple operation and management, and beautify the environment. They have broad application prospects in rural areas with weak economic strength in our country. The matrix is the skeleton of the constructed wetland, and its particle size distribution, porosity, chemical composition, etc. are a very important factor affecting the purification effect and service life of the wetland. The matrix not only directly removes pollutants through physical filtration, adsorption and precipitation, ion exchange, and chemical chelation reactions, but also provides carriers and nutrients for plants in wetlands, and provides an attachment surface for microorganisms, playing a role in the purification of constructed wetlands. play an irreplaceable role.

The sludge in the water supply plant comes from the sludge discharge of the water plant, which is mainly composed of the backwash drainage of the filter and the sludge discharge of the sedimentation tank or clarification tank. The urban water supply plant purifies the water source through a series of processes such as coagulation, sedimentation, filtration and disinfection, removes suspended matter, colloidal matter and other impurities in the raw water, and supplies water that meets the water quality requirements to users in the form of pipe network distribution. While producing a large amount of domestic water, a large amount of waste water and sludge will also be produced, and the sludge from the water supply plant is a kind of solid waste, which is generally treated by urban sewage plants, mud cake disposal, land disposal, and sanitary landfill This will increase the follow-up treatment process of the water supply plant and increase the cost of treatment. However, due to the low permeability coefficient of the sludge, it is not suitable to be directly used as the matrix of the constructed wetland. However, if the sludge from the water supply plant is used to produce ceramsite , and used as the substrate of artificial wetland to treat domestic sewage, realizing the harmless, resourceful and industrialized treatment of sludge from water supply plants, which is conducive to the protection of land resources and water resources, and reduces construction investment and operating costs. It has high use value in economic, social and environmental aspects.

In view of the above-mentioned defects, the designer is actively researching and innovating in order to create a constructed wetland matrix and its preparation method using purified water sludge to make it more industrially useful.

Contents of the invention

In order to solve the above-mentioned technical problems, the object of the present invention is to provide a constructed wetland substrate prepared from water purification sludge and a method thereof.

A kind of artificial wetland matrix prepared by utilizing water purification sludge of the present invention comprises matrix matrix and cyanobacteria press filtrate;

The cyanobacteria press filtrate is adjusted to pH 6.8-7.2 by sodium hydroxide;

The matrix matrix is made by compounding and sintering the bentonite after the water purification sludge from the water supply plant is calcined and acid leached for pretreatment.

Further, the water purification sludge of the water supply plant has a particle size of 30-90 μm, a silicon element content of 24-26%, an iron element mass content of 20-30%, an aluminum element mass content of 2-5%, and a calcium element mass content of The content is 0.5-1.0%.

Further, the cyanobacteria pressure filtration liquid is obtained by adding ferric chloride after the cyanobacteria crushing treatment.

A method for preparing a constructed wetland matrix prepared from purified water sludge, the specific preparation steps are:

Use sodium hydroxide to adjust the pH of the press-filtrate to 6.8-7.2, then mix the adjusted-pH press-filtrate with the matrix matrix at a mass ratio of 10:1, put it into an ultrasonic oscillator, and ultrasonically oscillate at a frequency of 30-40kHz for impregnation After 2-3 hours, filter and separate to obtain a filter cake, and vacuum freeze-dry to obtain the constructed wetland substrate. In the present invention, cyanobacteria are broken to form cyanobacteria mud, and the cyanobacteria mud is deeply dehydrated by hot pressure filtration, and ferric chloride is added to promote the flocculation between cyanobacteria cells, so there is a large amount of trivalent in the filtrate produced by the dehydration of cyanobacteria mud Iron ions, and ferric ions can be attached through charge neutralization and subsequent matrix matrix flocculation to improve the adsorption and removal effect on phosphorus, while heating the cyanobacteria mud will dissolve the extracellular capsular polysaccharides of cyanobacteria, forming a rich extracellular Press filtration of capsular polysaccharides, rheological mucus and protein; then use sodium hydroxide to adjust the pH of the press filter to a specific range to keep the extracellular capsular polysaccharides, rheological mucus and protein content in the press filter at a high value, iron ions The content is also at a high value, and then impregnated by ultrasonic vibration to make the press-filtrate loaded on the surface of the matrix matrix and in the internal void, because these extracellular polymers in the press-filtrate have a loose structure and fluidity, they can be loaded on the surface of the matrix matrix. Increase the distance between the matrix matrix and improve its permeability as a wetland matrix. In addition, these extracellular polymers have a flocculation and chelation effect, and have the effect of adsorbing and removing pollutants in wetland water quality.

Further, the preparation steps of the press filtrate are:

Take cyanobacteria and put them into a wall breaking machine to crush them to obtain cyanobacteria mud. Adjust the moisture content of cyanobacteria mud to 90% with water and put it into the reaction kettle. Stir at a speed of 200-300r/min. During the stirring process, add cyanobacteria mud to dry Weight 25% ferric chloride, raise the temperature of the reactor to 80° C., move it into a filter press device, and press filter at a pressure of 0.2 MPa to obtain a press filter liquid.

Further, the preparation steps of the matrix matrix are:

According to the mass ratio of 3:2, the pretreated water purification sludge and bentonite are mixed and put into a high-temperature calciner. Firstly, the temperature is raised to 550°C at a heating rate of 5°C/min, and the temperature is raised to 900-1150°C after calcination for 10 minutes. After heat preservation and calcination for 30-40 minutes, the matrix matrix is obtained. In the water purification sludge used in the present invention, the main constituent elements are Si, Al, Fe, so the phosphorus pollutants in the wetland water quality have strong adsorption capacity, and its main inorganic components are silicon dioxide, aluminum oxide and iron oxide. Mainly, it meets the raw material requirements for the preparation of ceramsite; the particle size of the water purification sludge is small, the plasticity is strong, and there is no need for drying and grinding, which saves production costs; in addition, the content of organic matter in the water purification sludge is high, and it contains a certain proportion of water. , organic matter volatilizes during high-temperature burning, which can play a pore-forming role, increase the porosity and specific surface area of the matrix, and then improve the adsorption and permeability of the matrix. At the same time, bentonite is used as an auxiliary material, and bentonite has good cementing ability , can be used as a binder to improve the strength of the final sintered matrix matrix;

Further, the preparation steps of the pretreated water purification sludge are:

Take the water purification sludge from the water supply plant, dry it, put it into a muffle furnace, and calcinate it at 400-450°C for 1-2 hours. The calcined water purification sludge and hydrochloric acid with a concentration of 2.5mol/L are mixed according to the solid-liquid ratio Mix and impregnate for 3 to 4 hours at a ratio of 1:1, filter and separate to obtain filter residue, and obtain pretreated water purification sludge after drying. The invention removes humic acid substances, some interfering metal ions and carbon components in the water purification sludge through high-temperature calcination and pickling treatment, and increases the pore diameter of the water purification sludge particles, thereby improving the water purification sludge Adsorption and permeability properties;

By means of the above solution, the present invention has at least the following advantages:

(1) the present invention at first by high-temperature calcination and pickling treatment, humic acid substances and some interfering metal ions and carbon components in the water purification sludge are removed, and the pore aperture of the water purification sludge particles is improved, thereby improving the Adsorption and permeability properties of water purification sludge;

(2) main constituent element is Si, Al, Fe in the water purification sludge that the present invention uses, therefore has stronger adsorption capacity to the phosphorus pollutant in wetland water quality, and its main inorganic component is silicon dioxide, aluminum oxide and Iron oxide is the main material, which meets the raw material requirements for the preparation of ceramsite; the particle size of the water purification sludge is small, the plasticity is strong, and there is no need for drying and grinding, which saves production costs; in addition, the content of organic matter in the water purification sludge is high, and contains certain Proportion of moisture, organic matter volatilizes during high-temperature burning, can play a role in pore formation, increase the porosity and specific surface area of the matrix, and then improve the adsorption and permeability of the matrix. At the same time, bentonite is used as an auxiliary material. Bentonite has better The cementing ability can be used as a binder to improve the strength of the final sintered matrix matrix;

(3) In the present invention, the cyanobacteria is broken to form cyanobacteria, and the cyanobacteria is dehydrated in depth by hot pressure filtration, and ferric chloride is added to promote flocculation between cyanobacteria cells. A large amount of ferric ions, and ferric ions can be attached through charge neutralization and subsequent matrix matrix flocculation to improve the adsorption and removal effect on phosphorus, while heating the cyanobacteria mud will dissolve the extracellular capsule polysaccharides of cyanobacteria, forming a rich Press filtrate containing extracellular capsular polysaccharides, rheological mucus and protein; then use sodium hydroxide to adjust the pH of the press filtrate to a specific range to keep the content of extracellular capsular polysaccharides, rheological mucus and protein in the press filtrate at a high value , the iron ion content is also at a high value, and then impregnated by ultrasonic vibration to make the press-filtrate load on the surface of the matrix matrix and in the internal voids, because these extracellular polymers in the press-filtrate have a loose structure and fluidity, they are loaded on the matrix matrix After the surface, the distance between the matrix and the matrix can be increased, and its permeability as a wetland matrix can be improved. In addition, these extracellular polymers have a flocculation and chelation effect, and can adsorb and remove pollutants in the wetland water quality.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention will be described in detail below.

Detailed ways

Below in conjunction with the examples, the specific implementation of the present invention will be further described in detail. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

(1) Take the water purification sludge from the water supply plant, dry it, put it into the muffle furnace, and calcinate it at 400-450°C for 1-2 hours, and press the calcined water purification sludge and hydrochloric acid with a concentration of 2.5mol/L The solid-liquid ratio is 1:1, mixed and impregnated for 3-4 hours, filtered and separated to obtain filter residue, and pretreated water purification sludge can be obtained after drying; the particle size of the water purification sludge is 30-90 μm, and the silicon content is 24-26 μm. %, the mass content of iron element is 20-30%, the mass content of aluminum element is 2-5%, and the content of calcium element is 0.5-1.0%; through high-temperature calcination and pickling treatment, the humic acid in the water purification sludge Substances and some interfering metal ions and carbon components are removed, and the pore size of the water purification sludge particles is increased, thereby improving the adsorption and permeability of the water purification sludge;

(2) Mix the above-mentioned pretreated water purification sludge and bentonite according to the mass ratio of 3:2 and put them into a high-temperature calciner, first raise the temperature to 550°C at a heating rate of 5°C/min, and then heat up to 900°C after calcining for 10 minutes. ~1150°C, heat preservation and calcination for 30 to 40 minutes to obtain the matrix matrix; the main constituent elements in the water purification sludge used in the present invention are Si, Al, and Fe, so it has a strong adsorption capacity for phosphorus pollutants in wetland water quality. The main inorganic components are silica, alumina and iron oxide, which meet the raw material requirements for the preparation of ceramsite; the particle size of water purification sludge is small, and the plasticity is strong, so it does not need to be dried and ground to save production costs; in addition, water purification The content of organic matter in the sludge is high, and contains a certain proportion of water. During the high-temperature burning process, the organic matter volatilizes, which can play a pore-forming role, increase the porosity and specific surface area of the matrix matrix, and then improve the adsorption and permeability of the matrix matrix. , while using bentonite as an auxiliary material, bentonite has good cementing ability and can be used as a binder to improve the strength of the matrix matrix obtained by final sintering;

(3) Take cyanobacteria and put them into a broken wall machine to obtain cyanobacteria mud after crushing. Use water to adjust the water content of cyanobacteria mud to 90% and put it into the reaction kettle. Stir at a speed of 200-300r/min. During the stirring process, add The ferric chloride of 25% of blue-green algae dry weight quality, after raising reaction kettle temperature to 80 ℃, moves in the filter press device, obtains press-filter with the pressure filtration of 0.2Mpa; Form blue-green algae mud after the broken wall of blue-green algae, and use The hot press filter method is used to dehydrate the cyanobacteria mud in depth, and ferric chloride is added to promote the flocculation between the cyanobacteria cells. Yes, there are a lot of ferric ions in the filtrate produced by the dehydration of the cyanobacteria mud, and the ferric ions can be neutralized by the charge. Flocculation and attachment with the subsequent matrix matrix improves the adsorption and removal effect on phosphorus, and heating the cyanobacteria mud will dissolve the extracellular capsular polysaccharides of cyanobacteria, forming a press filter rich in extracellular capsular polysaccharides, rheological mucus and protein;

(4) Use sodium hydroxide to adjust the pH of the above-mentioned filtrate to 6.8 to 7.2, and then mix the adjusted pH filtrate and the matrix matrix according to a mass ratio of 10:1 and then put them into an ultrasonic oscillator. The filter cake was obtained by filtering and separating by frequency ultrasonic oscillation for 2-3 hours, and the constructed wetland matrix was obtained after vacuum freeze-drying. First, use sodium hydroxide to adjust the pH of the press-filtrate to a specific range, keep the extracellular capsular polysaccharide, rheological mucus, and protein content in the press-filtrate at a high value, and the iron ion content is also at a high value, and then impregnate with ultrasonic vibration to make the press The filtrate is loaded on the surface of the matrix matrix and in the internal voids. Since the extracellular polymers in the filter press fluid have a loose structure and fluidity, they can increase the distance between the matrix matrix and improve its function as a wetland matrix after being loaded on the surface of the matrix matrix. In addition, these extracellular polymers have a flocculation and chelation effect, and have the effect of adsorbing and removing pollutants in wetland water quality.

Example 1

(1) Take the water purification sludge from the water supply plant and put it into the muffle furnace after drying, and calcinate it at 400°C for 1 hour. The calcined water purification sludge and hydrochloric acid with a concentration of 2.5mol/L are calculated as follows: 1:1 mixing and impregnation for 3 hours, filtration and separation to obtain filter residue, and pretreatment water purification sludge after drying;

(2) Mix the above-mentioned pretreated water purification sludge and bentonite according to the mass ratio of 3:2 and put them into a high-temperature calciner, first raise the temperature to 550°C at a heating rate of 5°C/min, and then heat up to 900°C after calcining for 10 minutes. ℃, heat preservation and calcination for 30 minutes to obtain the matrix matrix;

(3) Take the blue-green algae and put it into the broken wall machine to obtain the blue-green algae mud after crushing, adjust the moisture content of the blue-green algae mud to 90% with water and put it in the reaction kettle, stir at a speed of 200r/min, and add the blue-green algae mud during the stirring process Dry weight 25% ferric chloride, after raising the temperature of the reactor to 80°C, move it into the filter press device, and obtain the press filter liquid with a pressure filter of 0.2Mpa;

(4) Use sodium hydroxide to adjust the pH of the above-mentioned filtrate to 6.8, and then mix the adjusted pH filtrate and the matrix matrix at a mass ratio of 10:1, then put them into an ultrasonic oscillator, and impregnate them with ultrasonic vibration at a frequency of 30 kHz. After 2 hours, the filter cake was obtained by filtration and separation, and the constructed wetland substrate was obtained after vacuum freeze-drying.

Example 2

(1) Take the water purification sludge from the water supply plant and put it into the muffle furnace after drying, and calcinate it at 430°C for 2 hours. The calcined water purification sludge and hydrochloric acid with a concentration of 2.5mol/L are calculated according to the solid-to-liquid ratio. 1:1 mixing and impregnation for 4 hours, filtration and separation to obtain filter residue, and pretreatment water purification sludge after drying;

(2) Mix the above-mentioned pretreated water purification sludge and bentonite according to the mass ratio of 3:2 and put them into a high-temperature calciner, first raise the temperature to 550 °C at a heating rate of 5 °C/min, and then heat up to 1000 °C after calcining for 10 min. ℃, heat preservation and calcination for 35 minutes to obtain the matrix matrix;

(3) Take the blue-green algae and put it into the broken wall machine to obtain the blue-green algae mud after crushing, adjust the moisture content of the blue-green algae mud to 90% with water, put it into the reaction kettle, stir at a speed of 250r/min, and add the blue-green algae mud during the stirring process Dry weight 25% ferric chloride, after raising the temperature of the reactor to 80°C, move it into the filter press device, and obtain the press filter liquid with a pressure filter of 0.2Mpa;

(4) Use sodium hydroxide to adjust the pH of the above-mentioned filtrate to 7.0, and then mix the adjusted pH filtrate and the matrix matrix at a mass ratio of 10:1 and put them into an ultrasonic oscillator, and impregnate them with ultrasonic vibration at a frequency of 35 kHz. After 2 hours, the filter cake was obtained by filtration and separation, and the constructed wetland substrate was obtained after vacuum freeze-drying.

Example 3

(1) Take the water purification sludge from the water supply plant and put it into the muffle furnace after drying, and calcinate it at 450°C for 2 hours. The calcined water purification sludge and hydrochloric acid with a concentration of 2.5mol/L are calculated according to the solid-to-liquid ratio. 1:1 mixing and impregnation for 4 hours, filtration and separation to obtain filter residue, and pretreatment water purification sludge after drying;

(2) Mix the above-mentioned pretreated water purification sludge and bentonite according to the mass ratio of 3:2 and put them into a high-temperature calciner, first raise the temperature to 550°C at a heating rate of 5°C/min, and then heat up to 1150°C after calcining for 10 minutes. ℃, heat preservation and calcination for 40 minutes to obtain the matrix matrix;

(3) Take the blue-green algae and put it into the broken wall machine to obtain the blue-green algae mud after crushing, adjust the moisture content of the blue-green algae mud to 90% with water and put it into the reaction kettle, stir at a speed of 300r/min, and add the blue-green algae mud during the stirring process Dry weight 25% ferric chloride, after raising the temperature of the reactor to 80°C, move it into the filter press device, and obtain the press filter liquid with a pressure filter of 0.2Mpa;

(4) Use sodium hydroxide to adjust the pH of the above-mentioned filtrate to 7.2, then mix the adjusted pH filtrate and the matrix matrix at a mass ratio of 10:1, put them into an ultrasonic oscillator, and impregnate them with ultrasonic oscillation at a frequency of 40kHz After 3 hours, the filter cake was obtained by filtration and separation, and the constructed wetland matrix was obtained after vacuum freeze-drying.

Comparative example

Comparative example 1:

The preparation methods of Comparative Example 1 and Example 1 of the present invention are basically the same, only the difference is that the treatment of step (1) is not carried out, that is, the purified water sludge is not subjected to high-temperature pickling pretreatment, and the artificial wetland matrix is also made;

Comparative example 2:

The preparation method of comparative example 2 and the embodiment of the present invention 1 are basically the same, only difference is that the treatment of step (2) is not carried out, that is, directly use the pretreated sludge as the matrix matrix, and also make the constructed wetland matrix;

Comparative example 3:

The preparation methods of Comparative Example 3 and Example 1 of the present invention are basically the same, except that the treatment of steps (3) and (4) is not carried out, that is, the matrix matrix is directly used as the constructed wetland matrix, and the constructed wetland matrix is also made ;

Comparative example 4:

The preparation method of Comparative Example 4 is basically the same as that of Example 1 of the present invention, except that the pH range of the filter press liquid is not adjusted in step (4) to be not between 6.8 and 7.2, and the constructed wetland matrix is also made.

Detection method

Embodiment 1～3 of the present invention and comparative example 1～3 are carried out performance detection respectively, and detection result is as shown in table 1:

Detection method:

(1) Permeability test: use a 70-type (imitation of the base horse) permeameter (Nanjing Hydropower Instrument Factory) for measurement, the higher the permeability coefficient, the better the permeability;

(2) Adsorption performance test: put the constructed wetland matrix into simulated water with 1.32 mg/L total phosphorus and 76 mg/L COD, and test the adsorption removal rate of total phosphorus and COD in the water after 10 days. The higher the adsorption performance, the better;

Table 1 performance test results

It can be seen from the test data in the above table that the wetland matrix finally prepared in Examples 1 to 3 of the present invention has excellent adsorption performance and permeability, which proves that the technical solution of the present application is highly feasible;

Comparing Example 1 of the present invention with Comparative Example 1, because Comparative Example 1 did not carry out the treatment of step (1), that is, did not carry out high-temperature pickling pretreatment to the water purification sludge, it was also made into a constructed wetland matrix, resulting in the final The adsorption and permeability of the wetland matrix are all reduced, which proves that the present invention first removes humic acid substances, some interfering metal ions and carbon components in the water purification sludge through high-temperature calcination and pickling treatment , increase the pore size of the water purification sludge particles, thereby improving the adsorption and permeability of the water purification sludge;

Comparing Example 1 of the present invention with Comparative Example 2, because Comparative Example 2 did not carry out the treatment of step (2), that is, directly used the pretreated sludge as the matrix matrix, and also made the artificial wetland matrix, resulting in the final wetland matrix The adsorptivity and permeability all significantly reduce, thus can confirm that the main constituent element is Si, Al, Fe in the water purification sludge that the present invention uses, therefore has stronger adsorption capacity to the phosphorus pollutant in wetland water quality, and its The main inorganic components are silica, alumina and iron oxide, which meet the raw material requirements for the preparation of ceramsite; the particle size of water purification sludge is small, and the plasticity is strong, so it does not need to be dried and ground to save production costs; in addition, water purification The content of organic matter in the sludge is high, and contains a certain proportion of water. During the high-temperature burning process, the organic matter volatilizes, which can play a pore-forming role, increase the porosity and specific surface area of the matrix matrix, and then improve the adsorption and permeability of the matrix matrix. , while using bentonite as an auxiliary material, bentonite has good cementing ability and can be used as a binder to improve the strength of the matrix matrix obtained by final sintering;

Embodiment 1 of the present invention is compared with comparative example 3 and comparative example 4, because comparative example 3 does not carry out the processing of step (3) and (4), promptly directly uses matrix matrix directly as artificial wetland matrix, makes artificial wetland matrix equally For the wetland matrix, in the step (4) of Comparative Example 4, the pH range of the press-filtrate was adjusted not to be between 6.8 and 7.2, and the artificial wetland matrix was also made into a constructed wetland matrix, resulting in a significant decrease in the adsorption and permeability of the final wetland matrix, which can be confirmed In the present invention, cyanobacteria are broken to form cyanobacteria mud, and the cyanobacteria mud is deeply dehydrated by hot pressure filtration, and ferric chloride is added to promote the flocculation between cyanobacteria cells, so there is a large amount of trivalent in the filtrate produced by the dehydration of cyanobacteria mud Iron ions, and ferric ions can be attached through charge neutralization and subsequent matrix matrix flocculation to improve the adsorption and removal effect on phosphorus, while heating the cyanobacteria mud will dissolve the extracellular capsular polysaccharides of cyanobacteria, forming a rich extracellular Press filtration of capsular polysaccharides, rheological mucus and protein; then use sodium hydroxide to adjust the pH of the press filter to a specific range to keep the extracellular capsular polysaccharides, rheological mucus and protein content in the press filter at a high value, iron ions The content is also at a high value, and then impregnated by ultrasonic vibration to make the press-filtrate loaded on the surface of the matrix matrix and in the internal void, because these extracellular polymers in the press-filtrate have a loose structure and fluidity, they can be loaded on the surface of the matrix matrix. Increase the distance between the matrix matrix and improve its permeability as a wetland matrix. In addition, these extracellular polymers have a flocculation and chelation effect, and have the effect of adsorbing and removing pollutants in wetland water quality.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements can be made without departing from the technical principle of the present invention. and modifications, these improvements and modifications should also be considered as the protection scope of the present invention.

Claims (7)

1. A constructed wetland matrix prepared from purified water sludge, characterized in that: it comprises matrix matrix and cyanobacteria press filtrate; The cyanobacteria press filtrate is adjusted to pH 6.8-7.2 by sodium hydroxide; The matrix matrix is made by compounding and sintering the bentonite after the water purification sludge from the water supply plant is calcined and acid leached for pretreatment. 2. A constructed wetland substrate prepared from water purification sludge according to claim 1, characterized in that: the particle size of the water purification sludge from the water supply plant is 30-90 μm, and the silicon content is 24-26% The mass content of iron element is 20-30%, the mass content of aluminum element is 2-5%, and the content of calcium element is 0.5-1.0%. 3 . The constructed wetland substrate prepared from water purification sludge according to claim 1 , wherein the cyanobacteria press filter is obtained by adding ferric chloride after the cyanobacteria are crushed and processed. 4 . 4. a kind of preparation method of the constructed wetland matrix that utilizes water purification sludge to prepare as claimed in claim 1, is characterized in that concrete preparation step is: Use sodium hydroxide to adjust the pH of the press-filtrate to 6.8-7.2, then mix the adjusted-pH press-filtrate with the matrix matrix at a mass ratio of 10:1, put it into an ultrasonic oscillator, and ultrasonically oscillate at a frequency of 30-40kHz for impregnation After 2-3 hours, filter and separate to obtain a filter cake, and vacuum freeze-dry to obtain the constructed wetland matrix. 5. a kind of preparation method of the constructed wetland substrate that utilizes water purification sludge to prepare according to claim 4, is characterized in that: the preparation step of described press filtrate is: Take cyanobacteria and put them into a wall breaking machine to crush them to obtain cyanobacteria mud. Adjust the moisture content of cyanobacteria mud to 90% with water and put it into the reaction kettle. Stir at a speed of 200-300r/min. During the stirring process, add cyanobacteria mud to dry Weight 25% ferric chloride, raise the temperature of the reactor to 80° C., move it into a filter press device, and press filter at a pressure of 0.2 MPa to obtain a press filter liquid. 6. a kind of preparation method of the constructed wetland matrix that utilizes water purification sludge to prepare according to claim 4 is characterized in that: the preparation step of described matrix matrix is: According to the mass ratio of 3:2, the pretreated water purification sludge and bentonite are mixed and put into a high-temperature calciner. Firstly, the temperature is raised to 550°C at a heating rate of 5°C/min, and the temperature is raised to 900-1150°C after calcination for 10 minutes. After heat preservation and calcination for 30-40 minutes, the matrix matrix is obtained. 7. A kind of preparation method of the constructed wetland matrix that utilizes water purification sludge to prepare according to claim 6, is characterized in that: the preparation step of described pretreatment water purification sludge is: Take the water purification sludge from the water supply plant, dry it, put it into a muffle furnace, and calcinate it at 400-450°C for 1-2 hours. The calcined water purification sludge and hydrochloric acid with a concentration of 2.5mol/L are mixed according to the solid-liquid ratio Mix and impregnate for 3 to 4 hours at a ratio of 1:1, filter and separate to obtain filter residue, and obtain pretreated water purification sludge after drying.