WO2020147303A1

WO2020147303A1 - Sludge-based dephosphoring material and preparation method therefor and treatment method for phosphorus-containing wastewater

Info

Publication number: WO2020147303A1
Application number: PCT/CN2019/098959
Authority: WO
Inventors: 汪印; 李智伟
Original assignee: 中国科学院城市环境研究所
Priority date: 2019-01-16
Filing date: 2019-08-02
Publication date: 2020-07-23
Also published as: CN109529756A

Abstract

A sludge-based dephosphorization material and a preparation method therefor and a treatment method for phosphorus-containing wastewater. The preparation method for a sludge-based dephosphorization material comprises: (1) air drying a dewatered sludge at a room temperature and under the condition of ventilation, and drying for 4-6h at 60-90℃ to obtain a dried sludge; (2) adding an oxidizing agent into the dried sludge, stirring for 2-4h, filtering, washing using water, and drying for 4-6h at 60-90℃ to obtain an oxidized sludge; (3) immersing the oxidized sludge into an inorganic metal salt solution, stirring for 2-4h, filtering, washing using water and drying for 4-6h at 60-90℃ to obtain a salt-immersed sludge; and (4) disposing the salt-immersed sludge into a pyrolyzing furnace for pyrolysis, cooling the obtained pyrolysed product and smashing.

Description

Sludge-based phosphorus removal material, preparation method thereof and phosphorus-containing sewage treatment method

Technical field

The invention belongs to the field of phosphorus-containing sewage treatment, and specifically relates to a sludge-based phosphorus removal material and a preparation method thereof and a method for treating phosphorus-containing sewage.

Background technique

As an essential nutrient element, phosphorus is an important nutrient element for the growth of animals and plants, and it is also a non-renewable resource. It is estimated that the world's phosphate rock reserves can only be maintained for about 50 years, and phosphorus will become a limiting factor for human and terrestrial life activities. However, excessive phosphorus entering the water environment will cause algae blooms and eutrophication of the water body, causing pollution to the environment. In recent years, China’s sewage phosphorus discharge standards have become more and more stringent. After 2006, the main standards of pollutant discharge standards for sewage treatment plants have been restricted from 1mg/L (A) and 1.5mg/L (B) to 0.5mg/L ( A) and 1mg/L (B).

Therefore, how to effectively remove phosphorus has attracted more and more attention. Some technologies for removing phosphorus from wastewater have been developed, including physical treatment (adsorption and membrane separation), chemical precipitation, and biotechnology. Among these technologies, adsorption technology is particularly suitable for dephosphorization treatment of low-phosphorus wastewater due to its high efficiency and low residual rate, and has gradually become a technology that has attracted much attention.

At the same time, in China, with the rapid economic development, the number of sewage treatment plants (WWTPs) has greatly increased, and the output of sewage sludge has also increased rapidly. According to reports, from 2007 to 2013, the amount of sludge produced increased by 13% per year. In 2013, 6.25 million tons of dry sludge was produced. Therefore, it is urgent to develop a method that can quickly treat sludge and utilize sludge products.

Summary of the invention

The invention aims to provide a new sludge-based phosphorus removal material, a preparation method thereof, and a treatment method of phosphorus-containing sewage.

Specifically, the present invention provides a method for preparing a sludge-based phosphorus removal material. The method includes the following steps:

(1) After the dewatered sludge is air-dried under room temperature and ventilation conditions, it is dried at 60-90°C for 4-6 hours to obtain dry sludge;

(2) Add an oxidant to the dried sludge obtained in step (1), stir for 2-4 hours, filter, wash with water, and then dry at 60-90°C for 4-6 hours to obtain oxidized sludge;

(3) Immerse the oxidized sludge obtained in step (2) in an inorganic metal salt solution, stir for 2-4 hours, filter, wash with water, and then dry at 60-90°C for 4-6 hours to obtain salt-leached sludge;

(4) The salt-leached sludge obtained in step (3) is placed in a pyrolysis furnace for pyrolysis, and then the resulting pyrolysis product is cooled and crushed to obtain a sludge-based phosphorus removal material.

The term "dewatered sludge" refers to the solid residue remaining after the wet sludge is dewatered by means of drainage, filtration, etc. The water content in the dewatered sludge is usually 5-40 wt%. The source of the sludge in the present invention is not particularly limited. It can be derived from activated sludge discharged from the secondary settling tank of a domestic sewage plant, physicochemical sludge discharged from a sedimentation tank or thickening tank of a water plant, and discharged from a thickening tank produced by industrial wastewater treatment. Physicochemical and biochemical mixed sludge, etc.

Preferably, the preparation method of the sludge-based phosphorus removal material provided by the present invention further includes step (1), pulverizing and sieving the dried sludge to control its particle size at 50-200 mesh.

Preferably, the oxidant is nitric acid solution and/or hydrogen peroxide.

Preferably, the concentration of the nitric acid solution is 0.05-5 mol/L.

Preferably, relative to 100 parts by weight of the dried sludge, the amount of the oxidant is 20-200 parts by weight.

Preferably, the metal in the inorganic metal salt solution is selected from at least one of iron, ferrous iron, aluminum and calcium. Specific examples of the inorganic metal salt solution include, but are not limited to: ferric chloride salt solution, ferric sulfate salt solution, ferrous chloride salt solution, ferrous sulfate salt solution, aluminum nitrate salt solution, calcium chloride salt solution At least one.

Preferably, the concentration of the inorganic metal salt solution is 0.01-1.0 mol/L.

Preferably, relative to 100 parts by weight of oxidized sludge, the amount of the inorganic metal salt solution is 100-300 parts by weight.

Preferably, the pyrolysis conditions include a pyrolysis temperature of 300-900°C, a pyrolysis temperature increase rate of 5-20°C/min, and a pyrolysis residence time of 0.5-4h.

The invention also provides a sludge-based phosphorus removal material prepared by the above method.

In addition, the present invention also provides a method for treating phosphorus-containing sewage, which includes using the above-mentioned sludge-based phosphorus removal material to perform phosphorus removal treatment on the phosphorus-containing sewage.

Preferably, the phosphorus content in the phosphorus-containing sewage is 1-500 mg/L.

Preferably, based on the phosphorus content in the phosphorus-containing sewage being 1 g, the amount of the sludge-based phosphorus removal material is 0.1-20 g.

Preferably, the dephosphorization treatment is performed under shaking conditions, and the conditions include a temperature of room temperature and a time of 2-10 h.

The invention uses dewatered sludge as a raw material substrate to prepare phosphorus removal materials, which can not only solve the problem of sludge treatment, but also realize the resource utilization of sludge, and at the same time enable the disposal of phosphorus in sewage to be well solved, achieving The environmental governance effect of "making waste and turning waste into treasure" is simple and low-cost. More importantly, the sludge-based phosphorus removal material prepared by the method provided by the present invention has a large adsorption capacity, high phosphorus removal efficiency, can be mass-produced, and is beneficial to the industrialization of the application.

BRIEF DESCRIPTION

Figure 1 is a scanning electron micrograph (SEM) of the sludge-based phosphorus removal material obtained in Example 1;

2 and 3 are diagrams of the phosphorus removal effect of the sludge-based phosphorus removal material obtained in Example 3.

detailed description

The embodiments of the present invention will be described in detail below. The examples of the embodiments are intended to explain the present invention, but should not be understood as limiting the present invention. If the specific technology or condition is not indicated in the embodiment, it shall be carried out according to the technology or condition described in the literature in the field or according to the product specification. The reagents or instruments used without the manufacturer's indication are all conventional products that are commercially available.

Example 1

(1) Dry the dewatered sludge (from a domestic sewage plant with a water content of 40% by weight) under room temperature and ventilation conditions, then dry it at 65°C for 6 hours, crush, and pass through a 200-mesh sieve to obtain dry sludge;

(2) Add a nitric acid solution with a concentration of 0.05 mol/L to the dried sludge obtained in step (1) (relative to 100 parts by weight of the dried sludge, the amount of nitric acid solution is 100 parts by weight), stir for 2 hours, and filter, Wash with deionized water several times, and then dry at 60°C for 4 hours to obtain oxidized sludge;

(3) Immerse the oxidized sludge obtained in step (2) in a ferric chloride salt solution with a concentration of 0.01 mol/L (relative to 100 parts by weight of oxidized sludge, the amount of ferric chloride salt solution is 100 parts by weight ), stirred for 2 hours, filtered, washed with deionized water several times, and then dried at 90°C for 4 hours to obtain salt-leached sludge;

(4) The salt-leached sludge obtained in step (3) is placed in a pyrolysis furnace for pyrolysis. The pyrolysis conditions include: pyrolysis temperature of 400℃, pyrolysis heating rate of 5℃/min, pyrolysis residence time After 0.5h, the resulting pyrolysis product is cooled and pulverized to obtain a sludge-based phosphorus removal material, denoted as CP-1. The scanning electron micrograph of the sludge-based phosphorus removal material CP-1 is shown in Figure 1. It can be seen from Figure 1 that after the above-mentioned steps, the surface of the sludge-based phosphorus removal material forms a large amount of amorphous containing metal ions. The flocs provide a material basis for further adsorption of phosphorus.

Put 0.1g of sludge-based phosphorus removal material CP-1 in a 200mL Erlenmeyer flask, and add 50mL of KH ₂ PO ₄ solution with a concentration of 10.0 mg/L. After shaking in a constant temperature shaking box for 4 hours at room temperature, the supernatant was taken to determine the phosphorus content. The phosphorus removal rates of the three parallel samples were 92.56%, 91.87%, and 92.66%, respectively.

Example 2

(1) Dry the dewatered sludge (from a sewage treatment plant in an industrial zone, with a water content of 5wt%) under room temperature and ventilation conditions, then dry it at 60°C for 5 hours, crush, and pass through a 200-mesh sieve to obtain dried sludge;

(2) Add a 2mol/L nitric acid solution to the dried sludge obtained in step (1) (with respect to 100 parts by weight of the dried sludge, the amount of nitric acid solution is 150 parts by weight), stir for 3h, filter, and Wash with deionized water several times, and then dry at 90°C for 6 hours to obtain oxidized sludge;

(3) Immerse the oxidized sludge obtained in step (2) in an aluminum nitrate salt solution with a concentration of 0.1 mol/L (with respect to 100 parts by weight of oxidized sludge, the amount of aluminum nitrate salt solution is 200 parts by weight), Stir for 4 hours, filter, wash with deionized water several times, and then dry at 60°C for 6 hours to obtain salt-leached sludge;

(4) Put the salt-leached sludge obtained in step (3) into a pyrolysis furnace for pyrolysis. The pyrolysis conditions include: pyrolysis temperature of 600°C, pyrolysis temperature rise rate of 10°C/min, and pyrolysis residence time It is 1 hour, and then the obtained pyrolysis product is cooled and pulverized to obtain a sludge-based phosphorus removal material, denoted as CP-2.

Put 0.1g of sludge-based phosphorus removal material CP-2 in a 200mL Erlenmeyer flask, and add 50mL of KH ₂ PO ₄ solution with a concentration of 10.0 mg/L. After shaking in a constant temperature shaking box for 4 hours at room temperature, the supernatant was taken to determine the phosphorus content. The phosphorus removal rates in the three parallel samples were 94.65%, 94.78%, and 93.89%, respectively.

Example 3

(1) Dry the dewatered sludge (from a water plant with a water content of 30wt%) under room temperature and ventilation conditions, then dry it at 90°C for 4 hours, crush, and pass through a 200-mesh sieve to obtain dried sludge;

(2) To the dried sludge obtained in step (1), add a 5mol/L nitric acid solution (with respect to 100 parts by weight of the dried sludge, the amount of nitric acid solution is 200 parts by weight), stir for 4h, filter, and use Wash with deionized water several times, and then dry at 80°C for 5 hours to obtain oxidized sludge;

(3) Immerse the oxidized sludge obtained in step (2) in a calcium chloride salt solution with a concentration of 1.0 mol/L (relative to 100 parts by weight of oxidized sludge, the amount of calcium chloride salt solution is 300 parts by weight ), stirred for 4 hours, filtered, washed with deionized water several times, and then dried at 90°C for 6 hours to obtain salt-leached sludge;

(4) Put the salt-leached sludge obtained in step (3) into a pyrolysis furnace for pyrolysis. The pyrolysis conditions include: pyrolysis temperature of 800°C, pyrolysis heating rate of 20°C/min, and pyrolysis residence time After 4 hours, the resulting pyrolysis product is cooled and pulverized to obtain a sludge-based phosphorus removal material, denoted as CP-3.

Put 0.1g of sludge-based phosphorus removal material CP-3 in a 200mL Erlenmeyer flask, and add 50mL of KH ₂ PO ₄ solution with a concentration of 10.0 mg/L. After shaking in a constant temperature shaking box for 4 hours at room temperature, the supernatant was taken to determine the phosphorus content. The phosphorus removal rates in the three parallel samples were determined to be 98.54%, 99.59%, and 99.65%, respectively.

Put 0.1g of sludge-based phosphorus removal material CP-3 into three 200mL conical flasks, and then add 50mL to the above three conical flasks with concentrations of 100.0mg/L, 200.0mg/L, and 500mg/L. L of KH ₂ PO ₄ solution. Shake in a constant temperature shaking box for 4 hours at room temperature, take the supernatant to determine the phosphorus content, and the phosphorus content in the three conical flasks was 88.92 mg/g, 185.90 mg/g, and 220.58 mg/g, respectively. The effect of the sludge-based phosphorus removal material CP-3 on phosphorus-containing wastewater treatment is shown in Figure 2. It can be seen from Figure 2 that with the increase of the initial phosphorus concentration in the phosphorus-containing wastewater, the adsorption capacity of the sludge-based phosphorus removal material on phosphorus gradually increases. When the concentration is 500 mg/L, the sludge-based phosphorus removal material has The adsorption capacity of phosphorus is about 230mg/g.

In addition, the above method is used to prepare the sludge-based phosphorus removal material. The difference is that the calcium chloride salt solution uses the same concentration and amount of ferric chloride salt solution, ferric sulfate salt solution, ferrous chloride salt solution, and sulfurous sulfate. Iron salt solution and aluminum nitrate salt solution were replaced, and sludge-based phosphorus removal materials MBC-1, MBC-2, MBC-3, MBC-4, MBC-5 were obtained respectively.

Put 0.1g of sludge-based phosphorus removal materials MBC-1, MBC-2, MBC-3, MBC-4, MBC-5 and MBC-6 (CP-3) into a 200mL Erlenmeyer flask, and add 50mL concentration It is 10.0mg/L KH ₂ PO ₄ solution. Shake in a constant temperature shaking box for 4 hours at room temperature, take the supernatant to determine the phosphorus content, and measure the phosphorus removal rate in three sets of parallel samples. The average value obtained is shown in Figure 3. It can be seen from Figure 3 that the sludge-based phosphorus removal material obtained by the method provided by the present invention has a removal rate of more than 95% for phosphorus in sewage, indicating that the sludge-based phosphorus removal material has a strong phosphorus removal rate. ability.

Comparative Example 1

The sludge-based phosphorus removal material was prepared according to the method of Example 1. The difference is that the step (2) is not included, but the dried sludge obtained in step (1) is directly treated with ferric chloride salt solution. The specific steps are as follows :

(1) After the dehydrated sludge is air-dried under room temperature and ventilation conditions, it is then dried at 65°C for 6 hours, crushed, and passed through a 200-mesh sieve to obtain dried sludge;

(2) Immerse the dried sludge obtained in step (1) in a ferric chloride salt solution with a concentration of 0.01 mol/L (relative to 100 parts by weight of dried sludge, the amount of ferric chloride salt solution is 100 parts by weight ), stirred for 2 hours, filtered, washed with deionized water several times, and then dried at 90°C for 4 hours to obtain salt-leached sludge;

(3) Put the salt-leached sludge obtained in step (2) into a pyrolysis furnace for pyrolysis. The pyrolysis conditions include: pyrolysis temperature of 400℃, pyrolysis temperature rise rate of 5℃/min, pyrolysis residence time It is 0.5h, and then the obtained pyrolysis product is cooled and crushed to obtain the reference sludge-based phosphorus removal material, which is recorded as DCP-1.

0.1g of reference sludge-based phosphorus removal material DCP-1 was placed in a 200mL conical flask, and 50mL of KH ₂ PO ₄ solution with a concentration of 10.0 mg/L was added. After shaking in a constant temperature shaking box for 4 hours at room temperature, the supernatant was taken to determine the phosphorus content. The phosphorus removal rates in the three parallel samples were 39.56%, 37.14%, and 38.54%.

Comparative Example 2

The sludge-based phosphorus removal material was prepared according to the method of Example 1, except that step (3) was not included, but the oxidized sludge obtained in step (2) was directly subjected to pyrolysis treatment. The specific steps are as follows:

(3) Put the oxidized sludge obtained in step (2) in a pyrolysis furnace for pyrolysis. The pyrolysis conditions include: pyrolysis temperature of 400℃, pyrolysis rate of 5℃/min, and pyrolysis residence time of 0.5 h. Afterwards, the obtained pyrolysis product is cooled and crushed to obtain a reference sludge-based phosphorus removal material, which is recorded as DCP-2.

Place 0.1g of reference sludge-based phosphorus removal material DCP-2 in a 200mL Erlenmeyer flask, and add 50mL of KH ₂ PO ₄ solution with a concentration of 10.0 mg/L. After shaking in a constant temperature shaking box for 4 hours at room temperature, the supernatant was taken to determine the phosphorus content. The phosphorus removal rates in the three parallel samples were measured to be 24.56%, 25.01%, and 24.87%, respectively.

It can be seen from the above results that the sludge-based phosphorus removal material obtained by the method provided by the present invention is used to treat phosphorus-containing sewage. For low-concentration phosphorus solutions, the removal efficiency is high, and for high-concentration phosphorus solutions, the adsorption capacity of the material is Large, that is, the sludge-based phosphorus removal material obtained by the method provided by the present invention has a good treatment effect for different levels of phosphorus-containing sewage systems.

The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the specific technical features described in the above specific embodiments can be combined in any suitable manner without contradictions. In order to avoid unnecessary repetition, the present invention does not describe various possible combinations.

In addition, various different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

A preparation method of sludge-based phosphorus removal material, characterized in that the method comprises the following steps:

(1) After the dewatered sludge is air-dried under room temperature and ventilation conditions, it is dried at 60-90°C for 4-6 hours to obtain dry sludge;

(2) Add an oxidant to the dried sludge obtained in step (1), stir for 2-4 hours, filter, wash with water, and then dry at 60-90°C for 4-6 hours to obtain oxidized sludge;

(3) Immerse the oxidized sludge obtained in step (2) in an inorganic metal salt solution, stir for 2-4 hours, filter, wash with water, and then dry at 60-90°C for 4-6 hours to obtain salt-leached sludge;

(4) The salt-leached sludge obtained in step (3) is placed in a pyrolysis furnace for pyrolysis, and then the resulting pyrolysis product is cooled and crushed to obtain a sludge-based phosphorus removal material.
The preparation method according to claim 1, characterized in that the method further comprises step (1), pulverizing and sieving the dried sludge, so as to control its particle size to 50-200 mesh.
The preparation method according to claim 1, wherein the oxidant is a nitric acid solution and/or hydrogen peroxide; the concentration of the nitric acid solution is 0.05-5 mol/L; relative to 100 parts by weight of the dry dirt Mud, the amount of the oxidant is 20-200 parts by weight.
The preparation method according to claim 1, wherein the metal in the inorganic metal salt solution is selected from at least one of iron, ferrous iron, aluminum and calcium; the concentration of the inorganic metal salt solution is 0.01- 1.0mol/L; relative to 100 parts by weight of oxidized sludge, the amount of the inorganic metal salt solution is 100-300 parts by weight.
The preparation method according to claim 1, wherein the pyrolysis conditions include a pyrolysis temperature of 300-900°C, a pyrolysis temperature rise rate of 5-20°C/min, and a pyrolysis residence time of 0.5-4h .
A sludge-based phosphorus removal material prepared by the method of any one of claims 1-5.
A method for treating phosphorus-containing sewage, the method comprising subjecting the phosphorus-containing sewage to a phosphorus removal material for phosphorus removal treatment, wherein the phosphorus removal material is the sludge-based phosphorus removal material according to claim 6.
The treatment method according to claim 7, wherein the phosphorus content in the phosphorus-containing sewage is 1-500 mg/L.
The treatment method according to claim 7, wherein the amount of the sludge-based phosphorus removal material is 0.1-20 g based on the phosphorus content in the phosphorus-containing sewage being 1 g.
The treatment method according to claim 7, wherein the phosphorus removal treatment is performed under shaking conditions, and the conditions include a temperature of room temperature and a time of 2-10 hours.