WO2021003789A1

WO2021003789A1 - Resource utilization method of sludge pyrolysis biochar

Info

Publication number: WO2021003789A1
Application number: PCT/CN2019/099328
Authority: WO
Inventors: 汪印; 李智伟
Original assignee: 中国科学院城市环境研究所
Priority date: 2019-07-09
Filing date: 2019-08-06
Publication date: 2021-01-14
Also published as: CN110255845A; CN110255845B

Abstract

A resource utilization method of sludge pyrolysis biochar, comprising: S1. performing extraction on sludge pyrolysis biochar by using an extraction agent I, an extraction agent II and an extraction agent III successively to obtain an extracted liquid and solid residue III; S2. concentrating the extracted liquid, and then performing ion exchange resin separation to obtain different metal ions and phosphate ions; S3. using magnesium ions and phosphate ions obtained in step S2 and an additionally added ammonium source as raw materials to prepare struvite, and carrying out washing, drying, water vapor activation and metal ion loading modification on the solid residue III in order to obtain a functional adsorption material.

Description

Resource utilization method of sludge pyrolysis biochar

Technical field

The invention belongs to the field of sludge pyrolysis charcoal treatment, and specifically relates to a resource utilization method of sludge pyrolysis charcoal.

Background technique

With the improvement of the service level of municipal facilities in modern cities, the amount of urban sludge produced gradually increases. Among many sludge resource utilization methods, sludge pyrolysis has the advantages of rapid treatment, thorough harmless treatment, good stability of treated sludge and energy recovery, etc., which has attracted increasing attention. Whether the content of heavy metals in biochar obtained from sludge pyrolysis meets the standard and its existence form greatly affects the further application of sludge pyrolysis biochar. Related studies have shown that heavy metals in sludge pyrolysis carbon will be enriched during the pyrolysis process. Although pyrolysis itself has a stabilizing effect on heavy metals in sludge, there are many existing technologies that use methods such as adding curing agents to stabilize heavy metals, but for the application of sludge pyrolysis biochar, heavy metals are limited Very strict. If the sludge pyrolysis biochar is applied to the soil rashly, under the action of the microorganisms in the soil in the future, the long-term soil environment change process may cause the heavy metals in the sludge pyrolysis biochar to change from stable to unstable State transformation. Therefore, if the total amount of heavy metals in the sludge pyrolysis biochar is not reduced to below the relevant national standards, it is just a fixation and stabilization, which will pose a long-term potential pollution risk to the environment.

At the same time, sludge pyrolysis biochar enriches metals during the pyrolysis process. After testing, in addition to a large amount of common metals such as aluminum and iron brought by flocculants, there are also precious metals such as gold and silver, especially in The sludge pyrolysis activated carbon made from industrial sludge is therefore very important to extract the metals from the sludge pyrolysis activated carbon.

Current research is mainly focused on the extraction and recovery of heavy metals, phosphorus and other elements in sludge. There has not yet been a report on the extraction and recovery of heavy metals, phosphorus and other elements in sludge pyrolysis activated carbon.

Summary of the invention

The present invention aims to provide a new resource utilization method of sludge pyrolysis biochar to realize the resource utilization of sludge pyrolysis biochar. The method can solve the bottleneck of heavy metal limitation in the application of sludge pyrolysis biochar. At the same time, the resources of general metals, phosphorus and other elements in sludge biochar are fully utilized.

Specifically, the present invention provides a resource utilization method of sludge pyrolysis biochar, which includes the following steps:

S1. Extraction: The sludge pyrolysis biochar is subjected to the first extraction with extractant I to obtain the first extract and solid residue I, and then the obtained solid residue I is subjected to the second extraction with extractant II. After leaching, the second leaching liquid and solid residue II are obtained, and then the solid residue II is subjected to the third leaching using extractant III to obtain the third leaching liquid and solid residue III; The extractant I is selected from at least one solution of citric acid, EDTA and sodium hydroxide, the extractant II is an inorganic acid solution, and the extractant III is a mixed solution of phosphoric acid and hydrogen peroxide;

S2, separation of metal ions and phosphate ions: the first, second, and third extracts are concentrated and then separated by ion exchange resin to obtain different metal ions and Phosphate ion

S3. Preparation of struvite and functional adsorption materials:

Using the magnesium ion and phosphate ion obtained in step S2 and the additionally added ammonium source as raw materials to prepare struvite;

The solid residue III is washed with water and then dried, and at least part of the dried product is activated by steam, and then the metal ions obtained in step S2 are used for load modification to obtain a functional adsorption material.

Further, in step S1, the conditions of the first extraction, the second extraction and the third extraction each independently include an extraction temperature of 25 to 95°C, an extraction time of 1h to 10d, and a solid The liquid ratio is (5～40)g:1L.

Further, the first extraction, the second extraction and the third extraction are all performed under ultrasonic conditions, and the ultrasonic frequency is 20-65 kHz.

Further, in step S1, the molar concentration of the extractant I and the extractant II is 0.01-5 mol/L, the molar concentration of phosphoric acid in the extractant III is 0.01-5 mol/L and the volume concentration of hydrogen peroxide It is 2-20%.

Further, the extractant II is selected from at least one of sulfuric acid, nitric acid and hydrochloric acid.

Further, in step S2, the ion exchange resin used in the ion exchange resin separation is selected from at least one of strongly acidic ion exchange resin, weakly acidic ion exchange resin, weakly basic ion exchange resin and chelating ion exchange resin .

Further, the resource utilization method of sludge pyrolysis biochar provided by the present invention further includes, after the ion exchange resin is separated, acidifying and regenerating the saturated adsorbed ion exchange resin, and the obtained heavy metal ion-containing eluent is used After the replacement of waste aluminum, alloy metal particles are made, and the obtained aluminum-containing solution is added as an auxiliary flocculant to the second settling tank of the sewage treatment plant.

Further, in step S3, in the process of preparing struvite, the amount of the magnesium ion, phosphate ion and the additional ammonium source added is such that the molar ratio of magnesium ion, phosphorus ion and ammonium ion is (1 to 1.8) :(0.8～1.5):(3.5～4.5).

Further, in step S3, in the washing process, the solid-liquid ratio is (5-40) kg: 1 m ³ .

Further, in step S3, the water vapor activation conditions include an activation temperature of 700-900° C., an amount of water vapor of 1 to 5 mL/min, and an activation time of 10 to 30 minutes.

Further, in step S3, the mode of load modification is co-precipitation modification.

Further, in step S3, the method further includes using the remaining part of the dried product as fertilizer.

The method provided by the present invention can effectively separate and recycle metal ions and phosphate ions in sludge pyrolysis biochar, wherein magnesium ions and phosphate ions are used to prepare struvite, and the final leaching residue can be used as fertilizer Or it can be made into a functional adsorption material to realize the resource utilization of sludge pyrolysis biochar.

Description of the drawings

Fig. 1 is a schematic diagram of a specific process of the resource utilization method of sludge pyrolysis biochar provided by the present invention.

Detailed ways

In the present invention, the sludge pyrolysis biochar refers to biochar made by pyrolysis using sludge as a raw material. The sludge pyrolysis biochar contains metal cations such as magnesium, lead, manganese, copper, zinc, calcium, iron, chromium, aluminum, and anions such as phosphate.

In the present invention, in step S1, the sludge pyrolysis biochar is subjected to staged leaching to realize the recovery of metal cations and phosphate anions. Among them, the first leaching is mainly used to recover phosphate, magnesium, lead, and manganese plasma, the second leaching is mainly used to recover metal cations such as copper, zinc, calcium, and iron, and the third leaching is mainly used For the recovery of chromium, iron, aluminum and other metal cations. The extractant I used in the first leaching is selected from at least one solution of citric acid, EDTA and sodium hydroxide, and the extractant II used in the second leaching is an inorganic acid solution. The leaching agent III used in the third leaching is a mixed solution of phosphoric acid and hydrogen peroxide. Wherein, the extractant II is preferably at least one selected from sulfuric acid, nitric acid and hydrochloric acid. In addition, the molar concentration of the extractant I and the extractant II is preferably 0.01-5 mol/L. The molar concentration of phosphoric acid in the extractant III is preferably 0.01-5 mol/L and the volume concentration of hydrogen peroxide is preferably 2-20%.

In the present invention, the conditions of the three leaching are not particularly limited, as long as the metal cation can be fully extracted. According to a preferred embodiment of the present invention, the conditions of the first extraction, the second extraction and the third extraction each independently include an extraction temperature of 25-95°C and an extraction time of 1h~ 10d, the solid-liquid ratio is (5-40)g:1L. In addition, in order to be more conducive to the dissolution of metal cations and phosphate ions, the first extraction, the second extraction and the third extraction are all preferably performed under ultrasonic conditions, and the ultrasonic frequency is preferably 20-65 kHz .

In the present invention, in step S2, the concentration conditions are such that the volume of the extract is reduced to (1/5 to 1/3) of the original solution. The leachate obtained from the three extractions is concentrated and then separated by ion exchange resin, and the mixed ions contained in each leachate are separated again by the difference in retention time, and a single ion is obtained at different retention times. For example, the extractant II mainly contains metal ions such as copper, zinc, calcium, and iron. After being separated by the ion exchange resin, these metal ions can be washed from the ion exchange resin column due to the difference in retention time. To achieve separation. In the same way, the phosphate and metal ions contained in the extractant I and the extractant III can also be separated. The type of ion exchange resin used for ion exchange resin separation after concentrating the leaching solution obtained by three extractions can be the same or different. For example, they can be independently selected from strong acid ion exchange resin, weak acid ion exchange resin, and weak acid ion exchange resin. At least one of the basic ion exchange resin and the chelating ion exchange resin should be specifically selected according to the types of metal cations contained therein, as long as the mixed metal ions contained in each can be separated into single metal ions.

According to a preferred embodiment of the present invention, the resource utilization method of sludge pyrolysis biochar provided by the present invention further includes, after the ion exchange resin is separated, acidifying and regenerating the saturated adsorbed ion exchange resin, and the obtained containing The eluent of heavy metal ions is replaced with waste aluminum to make alloy metal particles, and the obtained aluminum-containing solution is added as an auxiliary flocculant to the secondary sedimentation tank of the sewage treatment plant. The type of acid used in the acidification regeneration treatment should be selected according to the type of heavy metal ions adsorbed in the ion exchange resin, and the heavy metal ions can be eluted from the ion exchange resin column.

In the present invention, in step S3, during the process of preparing struvite (magnesium ammonium phosphate), magnesium ions and phosphate ions extracted from sludge pyrolysis activated carbon are used as raw materials. In this process, additional ammonium It may also require additional magnesium sources (in the case of insufficient magnesium sources recovered). Among them, the amount of each raw material is preferably such that the molar ratio of magnesium ion, phosphorous ion and ammonium ion is (1 to 1.8): (0.8 to 1.5): (3.5 to 4.5). The specific preparation process of the struvite is well known to those skilled in the art, and will not be repeated here.

In the present invention, in step S3, the washing conditions generally include that the solid-to-liquid ratio may be (5-40) kg: 1 m ³ , and the number of washing times may be 2 to 4 times. After the washing, sedimentation and separation, solid drying, and drying products are used to prepare functional adsorption materials, or a part is used to prepare functional adsorption materials and the remaining part is used as fertilizer for garden flowers. In the preparation process of the functional adsorption material, the dried product needs to be activated by water vapor first, and then the metal ion (for example, at least one of iron ion, calcium ion, magnesium ion, and aluminum ion) obtained in step S2 is used. Load modification. Wherein, the water vapor activation conditions include that the activation temperature is preferably 700 to 900° C., the amount of water vapor is preferably 1 to 5 mL/min, and the activation time is preferably 10 to 30 minutes. In addition, the loading modification method is co-precipitation modification. Specifically, the solid residue III after steam activation and the metal ions obtained in step S2 (at least one of iron, calcium, magnesium, and aluminum) A) is dissolved in a solvent, and then the pH value of the system is adjusted to alkaline so that the above metal ions are precipitated on the surface of the solid residue III, and then the functional adsorption material can be obtained by drying. The functional adsorption material can be used to adsorb phosphorus element in phosphorus-containing wastewater.

According to a specific embodiment of the present invention, as shown in FIG. 1, the resource utilization method of sludge pyrolysis biochar includes using a composite leaching agent for grading leaching (in the classification During the leaching process, the best leaching process conditions can be continuously optimized), centrifugal filtration is used to separate the leaching solid (solid residue Ⅲ) and the leaching liquid phase (first extract, second extract) And the third leaching solution); after leaching, the liquid phase is concentrated and then separated by ion exchange resin to obtain different metal ions and phosphate ions. The magnesium ions and phosphate ions obtained are prepared with additional ammonium salt. Struvite; after the ion exchange resin is separated, the saturated adsorbed ion exchange resin is acidified and regenerated, the regenerated resin is reused, and the eluate containing heavy metal ions obtained from the acidification of the resin is replaced with waste aluminum to make alloy metal particles. The alloy metal particles can be further smelted using conventional procedures, and the resulting aluminum-containing solution can be used as an auxiliary flocculant to be added to the secondary sedimentation tank of a sewage treatment plant, and the eluate without heavy metal ions obtained from resin acidification can be used as a leaching agent. It is used to the extraction step; after the extraction, a part of the solid is washed and used as fertilizer for flowers and landscaping, and the other part is activated and modified into an adsorption material.

The present invention will be described in detail below through examples.

Example 1

S1. Extraction: The sludge pyrolysis biochar is extracted with extractant I (a citric acid aqueous solution with a concentration of 0.01mol/L) at a temperature of 25°C, a solid-to-liquid ratio of 40g:1L, and an ultrasonic frequency of 65kHz for 10 days. Centrifugal separation, the first extract and solid residue I are obtained, and then the obtained solid residue I is extracted with extractant II (aqueous sulfuric acid solution with a concentration of 5mol/L) at a temperature of 75°C, a solid-liquid ratio of 5g:1L, and ultrasonic frequency After leaching for 1 hour at 20kHz and centrifugal separation, the second leaching liquid and solid residue II are obtained, and then the solid residue II is used as extractant III (a mixed solution of phosphoric acid and hydrogen peroxide, wherein the molar concentration of phosphoric acid is 0.01 mol/L and the volume concentration of hydrogen peroxide is 2%) at a temperature of 40°C, a solid-liquid ratio of 5g:1L, and an ultrasonic frequency of 65kHz for 10 days of extraction, centrifugal separation to obtain the third extract and solid residue III.

S2. Separation of metal ions and phosphate ions: After the first extract is concentrated to a quarter of the original volume, it is separated by weakly acidic ion exchange resin. The eluent is acetic acid solution, and the retention time Different sequentially obtain phosphate ion, magnesium ion and a small amount of lead ion and manganese ion. The second extraction solution is concentrated and separated by strong acid ion exchange resin, wherein the eluent is a hydrochloric acid solution, and copper ions, zinc ions, calcium ions and iron ions are sequentially obtained by using different retention times. The third extract was concentrated to a quarter of the original volume and then separated by weakly basic ion exchange resin. Among them, the eluent was an aqueous ammonia solution, and chromium ions and a small amount of iron ions and Aluminum ion.

S3. Preparation of struvite and functional adsorption materials:

The magnesium ion and phosphate ion obtained in step S2 and the additional ammonium source are used as raw materials to prepare struvite, wherein the amount of each substance is such that the molar ratio of magnesium ion, phosphorus ion and ammonium ion is 1:0.8:3.5.

The solid residue III was washed three times with water solvent under the condition of solid-liquid ratio of 5kg:1m ³ , sedimentation and separation, solid drying, and then a part of the dried product was directly used as flower fertilizer, and the remaining part was activated by steam (water vapor The activation conditions include a temperature of 800°C, a water vapor consumption of 2 mL/min, and an activation time of 20 min), and then the iron ions obtained in step S2 are used for load modification to obtain a functional adsorption material, which can be used to adsorb phosphorus-containing wastewater Element of phosphorus.

Example 2

S1. Extraction: The sludge pyrolysis biochar is extracted with extractant I (sodium hydroxide aqueous solution with a concentration of 5mol/L) at a temperature of 95℃, a solid-to-liquid ratio of 20g:1L, and an ultrasonic frequency of 65kHz for 1h. Centrifugal separation, the first extract and solid residue I are obtained, and then the obtained solid residue I is extracted with extractant II (aqueous nitric acid solution with a concentration of 0.01 mol/L) at a temperature of 25°C, a solid-to-liquid ratio of 40g:1L, ultrasonic Leaching for 10 days at a frequency of 65kHz, centrifugal separation, to obtain the second extract and solid residue II, and then use the solid residue II with extractant III (a mixed solution of phosphoric acid and hydrogen peroxide, where the molar concentration of phosphoric acid is 5mol/L and the volume concentration of hydrogen peroxide is 20%) at a temperature of 75°C, a solid-liquid ratio of 40g:1L, and an ultrasonic frequency of 20kHz for 1 hour, centrifugal separation, to obtain the third extract and solid residue III.

S2. Separation of metal ions and phosphate ions: After the first extract is concentrated to one third of the original volume, it is separated with a strong acid ion exchange resin. The eluent is a hydrochloric acid solution, and the retention time is Different order to obtain phosphate ion and magnesium ion. The second leaching solution was concentrated to a quarter of the original volume and then separated by a weakly acidic ion exchange resin. Among them, the eluent was an acetic acid solution, and the difference in retention time was used to sequentially obtain copper ions, zinc ions, calcium ions and Iron ion. The third leaching solution is concentrated to one-fifth of the original volume and then separated by a strong alkaline ion exchange resin, where the eluent is sodium hydroxide solution, and chromium ions and aluminum ions are sequentially obtained by using the difference in retention time.

S3. Preparation of struvite and functional adsorption materials:

The magnesium ion and phosphate ion obtained in step S2 and the additional ammonium source are used as raw materials to prepare struvite, wherein the amount of each substance is such that the molar ratio of magnesium ion, phosphorus ion and ammonium ion is 1.8:1.5:4.5.

The solid residue III was washed three times with a water solvent under the condition of a solid-liquid ratio of 20kg: 1m ³ , sedimentation and separation, solid drying, and then a part of the dried product was directly used as flower fertilizer, and the remaining part was activated by steam (water vapor The activation conditions include a temperature of 900°C, a water vapor dosage of 5 mL/min, and an activation time of 10 min), and then the calcium ions obtained in step S2 are used for load modification to obtain a functional adsorbent, which can be used to adsorb phosphorus-containing wastewater Element of phosphorus.

Example 3

S1. Extraction: The sludge pyrolysis biochar is extracted with extractant I (a 2mol/L EDTA aqueous solution) at a temperature of 40℃, a solid-to-liquid ratio of 20g:1L, and an ultrasonic frequency of 40kHz for 5 days, and centrifuged. , Get the first leaching liquid and solid residue I, and then use leaching agent II (hydrochloric acid solution with a concentration of 2mol/L) to obtain the solid residue I at a temperature of 25℃, a solid-liquid ratio of 20g:1L, and an ultrasonic frequency of 40kHz. After leaching for 5 days and centrifugal separation, the second leaching liquid and solid residue II are obtained, and then the solid residue II is used as extractant III (a mixed solution of phosphoric acid and hydrogen peroxide, wherein the molar concentration of phosphoric acid is 2 mol/L And the volume concentration of hydrogen peroxide is 10%). It is leached for 5 days at a temperature of 35°C, a solid-liquid ratio of 20g:1L, and an ultrasonic frequency of 40kHz, and centrifuged to obtain the third leaching solution and solid residue III.

S2. Separation of metal ions and phosphate ions: After the first extract is concentrated to a quarter of the original volume, it is separated with a weakly acidic ion exchange resin. The eluent is an acetic acid solution and the retention time Different sequentially obtain phosphate ion, magnesium ion and a small amount of lead ion and manganese ion. The second extract is concentrated to one-fifth of the original volume and separated by chelating ion exchange resin. The eluent is a hydrochloric acid solution, and the difference in retention time is used to obtain copper ions, zinc ions, and calcium ions. And iron ions. After the third leaching solution is concentrated to a quarter of the original volume, it is separated with a weakly basic ion exchange resin, where the eluent is an aqueous ammonia solution, and chromium ions and a small amount of aluminum ions are sequentially obtained by the difference in retention time.

S3. Preparation of struvite and functional adsorption materials:

The magnesium ion and phosphate ion obtained in step S2 and the additional ammonium source are used as raw materials to prepare struvite, wherein the amount of each substance is such that the molar ratio of magnesium ion, phosphorus ion and ammonium ion is 1.5:1.2:4.

The solid residue Ⅲ solid-liquid ratio of the solvent is ethanol 40kg: 1M washed 3 times under ^three conditions, sedimentation separation, and drying the solid, after drying the product was used directly as a part of fertilizers, and the remainder by steam activation (water vapor The activation conditions include a temperature of 900°C, a water vapor amount of 5ml/min, and an activation time of 20min), and then the aluminum ions obtained in step S2 are used for load modification to obtain a functional adsorption material, which can be used to adsorb phosphorus-containing wastewater Element of phosphorus.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art will not depart from the principle and purpose of the present invention. Under the circumstances, changes, modifications, substitutions and modifications can be made to the above-mentioned embodiments within the scope of the present invention.

Claims

A resource utilization method of sludge pyrolysis biochar is characterized in that the method includes the following steps:

S1. Extraction: The sludge pyrolysis biochar is subjected to the first extraction with extractant I to obtain the first extract and solid residue I, and then the obtained solid residue I is subjected to the second extraction with extractant II. After leaching, the second leaching liquid and solid residue II are obtained, and then the solid residue II is subjected to the third leaching using extractant III to obtain the third leaching liquid and solid residue III; The extractant I is selected from at least one solution of citric acid, EDTA and sodium hydroxide, the extractant II is an inorganic acid solution, and the extractant III is a mixed solution of phosphoric acid and hydrogen peroxide;

S2, separation of metal ions and phosphate ions: the first, second, and third extracts are concentrated and then separated by ion exchange resin to obtain different metal ions and Phosphate ion

S3. Preparation of struvite and functional adsorption materials:

Using the magnesium ion and phosphate ion obtained in step S2 and the additionally added ammonium source as raw materials to prepare struvite;

The solid residue III is washed with water and then dried, and at least part of the dried product is activated by steam, and then the metal ions obtained in step S2 are used for load modification to obtain a functional adsorption material.
The resource utilization method of sludge pyrolysis biochar according to claim 1, characterized in that, in step S1, the conditions of the first extraction, the second extraction and the third extraction are independent of each other The ground includes extraction temperature of 25～95℃, extraction time of 1h～10d, solid-liquid ratio of (5～40)g:1L; the first extraction, second extraction and third extraction The extraction was carried out under ultrasonic conditions, and the ultrasonic frequency was 20-65 kHz.
The resource utilization method of sludge pyrolysis biochar according to claim 1, wherein in step S1, the molar concentration of the extractant I and the extractant II is 0.01-5 mol/L, and The molar concentration of phosphoric acid in the extractant III is 0.01-5 mol/L and the volume concentration of hydrogen peroxide is 2-20%; the extractant II is selected from at least one of sulfuric acid, nitric acid and hydrochloric acid.
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, characterized in that, in step S2, the ion exchange resin used for separation of the ion exchange resin is selected from strongly acidic ion exchange At least one of resin, weakly acidic ion exchange resin, weakly basic ion exchange resin and chelating ion exchange resin.
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, characterized in that, the method further comprises after the ion exchange resin is separated, performing saturated adsorption on the ion exchange resin After acidification regeneration treatment, the obtained eluate containing heavy metal ions is replaced with waste aluminum to make alloy metal particles, and the obtained aluminum-containing solution is added as an auxiliary flocculant to the secondary settling tank of the sewage treatment plant.
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, wherein in step S3, in the process of preparing struvite, the magnesium ion and phosphate ion And the amount of the additional ammonium source added makes the molar ratio of magnesium ion, phosphorus ion and ammonium ion (1～1.8):(0.8～1.5):(3.5～4.5).
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, wherein in step S3, in the washing process, the solid-to-liquid ratio is (5-40) kg :1m 3 .
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, wherein in step S3, the water vapor activation conditions include an activation temperature of 700 to 900°C, water The amount of steam is 1-5mL/min, and the activation time is 10-30min.
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, characterized in that, in step S3, the method of loading modification is co-precipitation modification.
The resource utilization method of sludge pyrolysis biochar according to any one of claims 1 to 3, characterized in that, in step S3, the method further comprises using the remaining part of the dried product as fertilizer.