Arsenic-containing sludge solidification resource reutilization method

Abstract

The invention relates to an arsenic-containing sludge solidification resource reutilization method which comprises the following steps: S1, sludge pretreatment: drying, crushing and sieving arsenic-containing sludge to obtain sludge powder; s2, charging and mixing: mixing the sludge powder, the nano clay and the ardealite, and adding water for dispersion; s3, acidification: dropwise adding dilute sulphuric acid into the dispersion liquid, and carrying out solid-liquid separation for later use; s4, heat treatment: pyrolyzing the separated solids in a nitrogen atmosphere to obtain a nano-modified sludge-based material; s5, zinc oxide modification treatment: respectively preparing a nano-modified sludge-based material and a zinc oxide nanoparticle ethanol dispersion liquid, mixing, performing ultrasonic treatment, centrifuging and drying to obtain a nano-modified sludge-based reinforcing material; s6, sewage treatment: mixing the nano-modified sludge-based reinforcing material with the sewage with the heavy metal content exceeding the standard in proportion, and centrifuging after full reaction to obtain water with the heavy metal content reaching the standard. The method has the advantages that arsenic in the sludge is effectively fixed, the treated sludge can be effectively used for sewage treatment, and the purpose of treating pollution with waste is achieved.

Description

Technical Field

[0001] The invention relates to the field of harmless treatment of sludge, and in particular to a method for solidifying and recycling arsenic-containing sludge. Background Art

[0002] Silt, as a common waste, mainly comes from the bottom sediments of water bodies such as rivers, lakes, and ponds. These silts often contain a large amount of heavy metals and other pollutants, such as arsenic. Arsenic is a toxic element, and long-term contact or ingestion can cause serious harm to human health. Once the benthic and water environmental parameters change, the bound arsenic in the sediment can release more mobile and bioavailable arsenic ions through dissolution, biodegradation, desorption, etc., seriously affecting the health of the aquatic ecosystem. Therefore, fixing the active arsenic in the silt into a stable arsenic that is difficult to migrate and is not bioavailable is one of the effective ways to solve arsenic pollution. How to effectively solidify heavy metal arsenic in silt has become an important research topic in the field of environmental protection.

[0003] Traditional methods for treating arsenic-containing sludge include landfilling and incineration, which occupy a large area and have low resource utilization, and are not in line with the trend of green development in the future. Therefore, for the harmless treatment of arsenic-containing sludge, stabilization / solidification treatment technology is currently mainly used. Researching and developing new sludge solidification and resource treatment technologies to achieve "waste treatment" is of great significance to protecting the ecological environment and human health. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for solidifying and recycling arsenic-containing sludge, aiming to overcome the many shortcomings of traditional methods for treating arsenic-containing sludge.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: a method for solidifying and recycling arsenic-containing sludge, which comprises the following steps:

[0006] S1. Sludge pretreatment: The arsenic-containing sludge is taken out from the oxidation pond and placed in a drying device. After drying to constant weight, it is taken out, crushed and sieved. The sieved powder is the pretreated sludge powder, which is sealed and stored in a dry environment for standby use;

[0007] S2. Adding and mixing: After mixing the sludge powder, nanoclay and phosphogypsum in proportion, adding water and stirring to obtain a dispersion;

[0008] S3. Acidification: Add dilute sulfuric acid to the dispersion, adjust the pH of the dispersion to 5-6, stir for 0.5-2h, separate the solid and liquid, and retain the separated solid for later use;

[0009] S4. Heat treatment: placing the separated solid in a heating device, heating it under a nitrogen atmosphere to pyrolyze it, and obtaining a nano-modified sludge-based material;

[0010] S5. zinc oxide modification treatment: preparing a nano-modified sludge-based material ethanol dispersion and a zinc oxide nanoparticle ethanol dispersion respectively, and then mixing the two dispersions and continuing ultrasonic dispersion treatment, after sufficient dispersion, centrifugation and drying, to obtain a nano-modified sludge-based reinforcement material;

[0011] S6. Wastewater treatment: Mix the nano-modified sludge-based reinforcement material with wastewater with excessive heavy metal content in proportion, stir to fully react, and then centrifuge. The separated solid material is used to treat the next batch of wastewater with excessive heavy metal content and recycled. The separated liquid is the water with standard heavy metal content.

[0012] On the basis of the above technical solutions, the present invention can also have the following further specific options.

[0013] Specifically, the drying temperature in S1 is controlled to be 100-105° C., the dried material is crushed using a crusher, and a 60-mesh sieve is used for screening.

[0014] Specifically, the sludge powder, nanoclay and phosphogypsum in S2 are mixed in a weight ratio of 3:0.5-1:0.8-1.2.

[0015] Specifically, the sludge powder, nanoclay and phosphogypsum in S2 are mixed and then fully ground and mixed using a grinding device.

[0016] Specifically, the mass fraction of the sludge powder in the dispersion obtained in S2 is 6.5-10.5%.

[0017] Specifically, the concentration of the dilute sulfuric acid added in S3 is 1-2 mol / L.

[0018] Specifically, in S4, the heating rate is controlled at 8-12°C / min, and after heating to 500°C, it is maintained for 2-3 hours and then naturally cooled to room temperature.

[0019] Specifically, the solid content of the nano-modified sludge-based material ethanol dispersion in S5 is 10-15wt%, and the solid content of the zinc oxide nanoparticle ethanol dispersion is 3-6wt%.

[0020] Specifically, the nano-modified sludge-based material ethanol dispersion and the zinc oxide nanoparticle ethanol dispersion in S5 are mixed in a weight ratio of 3.2-6.4:1.

[0021] Specifically, the nano-modified sludge-based reinforcing material is mixed with sewage with excessive heavy metal content in a weight ratio of 0.005-0.015:1, and the mixture is reacted under stirring conditions for 10-15 hours.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a new direction for the resource application of arsenic-containing sludge solidification. After the arsenic-containing sludge is dried and crushed, nano-clay and phosphogypsum are mixed and acidified, and then pyrolysis is performed in an anaerobic environment to prepare a nano-modified sludge-based material. Nano-clay is used to increase its specific surface area. Pyrolysis and phosphogypsum can change the form of arsenic, so that arsenic mainly exists in an oxidizable state and an RNU residue state, thereby reducing its mobility and bioavailability, and significantly reducing potential ecological risks. Subsequently, the sludge-based material is modified with zinc oxide nanoparticles to obtain a nano-modified sludge-based reinforced material, which has a strong electron transfer ability and adsorption ability, can form a complex with heavy metal ions to achieve adsorption, and promotes the re-stabilization of heavy metals.

[0024] Adding the nano-modified sludge-based reinforcement material to sewage can reduce the mobility and bioavailability of heavy metals. The nano-modified sludge-based reinforcement material has a higher ash content, can produce a higher cation exchange capacity, and is more conducive to the adsorption of heavy metals. The method provided by the present invention has simple steps and is expected to realize the resource recovery of arsenic-containing sludge and achieve "waste treatment". DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below in conjunction with specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] To avoid redundant description, the pharmaceutical raw materials used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0027] Example 1

[0028] A method for solidifying and recycling arsenic-containing sludge, comprising the following steps:

[0029] S1. Sludge pretreatment: The arsenic-containing sludge is taken out from the oxidation pond and placed in a drying device (blast drying oven), the temperature is set to 100°C, and after drying to constant weight, it is taken out, crushed using a crusher and passed through a 60-mesh sieve. The powder after sieving is the pretreated sludge powder, which is sealed and stored in a dry environment for standby use;

[0030] S2. Adding and mixing: Mix the sludge powder, nanoclay and phosphogypsum in a weight ratio of 3:1:0.8, first use a grinding device to fully grind and mix, then add water and stir to obtain a dispersion, the mass fraction of the sludge powder in the dispersion is 6.5%;

[0031] S3. Acidification: dilute sulfuric acid was added dropwise to the dispersion, the concentration of dilute sulfuric acid was 2 mol / L, the pH of the dispersion was adjusted to 5, stirred for 0.5 h, solid-liquid separation was performed, and the separated solid was retained for standby use;

[0032] S4. Heat treatment: The separated solid was placed in a heating device, heated under a nitrogen atmosphere, and pyrolyzed. The heating rate in S4 was controlled at 10 ° C / min, heated to 500 ° C and maintained for 2h pyrolysis, and then naturally cooled to room temperature to obtain a nano-modified sludge-based material;

[0033] S5. Zinc oxide modification treatment: prepare nano-modified sludge-based material ethanol dispersion and zinc oxide nanoparticle ethanol dispersion respectively, the solid content of the nano-modified sludge-based material ethanol dispersion in S5 is 10wt%, and the solid content of the zinc oxide nanoparticle ethanol dispersion is 6wt%, then mix the two dispersions and continue ultrasonic dispersion treatment, the nano-modified sludge-based material ethanol dispersion and the zinc oxide nanoparticle ethanol dispersion are mixed in a weight ratio of 6.4:1, after fully dispersed, centrifugally separated and dried to obtain the nano-modified sludge-based reinforcement material;

[0034] S6. Wastewater treatment: Mix the nano-modified sludge-based reinforcement material with wastewater with excessive heavy metal content in a weight ratio of 0.005:1. After mixing, react under stirring conditions for 15 hours, and centrifuge. The separated solid material is used to treat the next batch of wastewater with excessive heavy metal content and recycled. The separated liquid is the water with standard heavy metal content.

[0035] Example 2

[0036] A method for solidifying and recycling arsenic-containing sludge, comprising the following steps:

[0037] S1. Sludge pretreatment: The arsenic-containing sludge is taken out from the oxidation pond and placed in a drying device (blast drying oven) at a temperature of 102°C. After drying to constant weight, the sludge is taken out and crushed using a crusher and passed through a 60-mesh sieve. The powder after sieving is the pretreated sludge powder, which is sealed and stored in a dry environment for standby use;

[0038] S2. Adding and mixing: Mix the sludge powder, nanoclay and phosphogypsum in a weight ratio of 3:0.8:0.9, first use a grinding device to fully grind and mix, then add water and stir to obtain a dispersion, the mass fraction of the sludge powder in the dispersion is 8.5%;

[0039] S3. Acidification: dilute sulfuric acid was added dropwise to the dispersion, the concentration of the dilute sulfuric acid was 2 mol / L, the pH of the dispersion was adjusted to 5, stirred for 1 h, solid-liquid separation was performed, and the separated solid was retained for standby use;

[0040] S4. Heat treatment: The separated solid was placed in a heating device, heated under a nitrogen atmosphere, and pyrolyzed. The heating rate in S4 was controlled at 8 ° C / min, heated to 500 ° C and maintained for 2 h of pyrolysis, and then naturally cooled to room temperature to obtain a nano-modified sludge-based material;

[0041] S5. Zinc oxide modification treatment: prepare nano-modified sludge-based material ethanol dispersion and zinc oxide nanoparticle ethanol dispersion respectively, the solid content of the nano-modified sludge-based material ethanol dispersion in S5 is 12wt%, and the solid content of the zinc oxide nanoparticle ethanol dispersion is 5wt%, then mix the two dispersions and continue ultrasonic dispersion treatment, the nano-modified sludge-based material ethanol dispersion and the zinc oxide nanoparticle ethanol dispersion are mixed in a weight ratio of 5:1, after sufficient dispersion, centrifugal separation, and drying, to obtain the nano-modified sludge-based reinforcement material;

[0042] S6. Wastewater treatment: Mix the nano-modified sludge-based reinforcement material with wastewater with excessive heavy metal content in a weight ratio of 0.008:1. After mixing, react under stirring conditions for 13 hours, and centrifuge. The separated solid material is used to treat the next batch of wastewater with excessive heavy metal content and recycled. The separated liquid is the water with standard heavy metal content.

[0043] Example 3

[0044] A method for solidifying and recycling arsenic-containing sludge, comprising the following steps:

[0045] S1. Sludge pretreatment: The arsenic-containing sludge is taken out from the oxidation pond and placed in a drying device (blast drying oven) at a temperature of 104°C. After drying to constant weight, the sludge is taken out and crushed using a crusher and passed through a 60-mesh sieve. The powder after sieving is the pretreated sludge powder, which is sealed and stored in a dry environment for standby use;

[0046] S2. Adding and mixing: Mix the sludge powder, nanoclay and phosphogypsum in a weight ratio of 3:0.6:1.1, first grind and mix them thoroughly using a grinding device, then add water and stir to obtain a dispersion, wherein the mass fraction of the sludge powder in the dispersion is 9.5%;

[0047] S3. Acidification: dilute sulfuric acid was added dropwise to the dispersion, the concentration of the dilute sulfuric acid was 1 mol / L, the pH of the dispersion was adjusted to 6, stirred for 1.5 h, solid-liquid separation was performed, and the separated solid was retained for standby use;

[0048] S4. Heat treatment: The separated solid was placed in a heating device, heated under a nitrogen atmosphere, and pyrolyzed. The heating rate in S4 was controlled at 9 ° C / min, heated to 500 ° C and maintained for 3h pyrolysis, and then naturally cooled to room temperature to obtain a nano-modified sludge-based material;

[0049] S5. Zinc oxide modification treatment: prepare nano-modified sludge-based material ethanol dispersion and zinc oxide nanoparticle ethanol dispersion respectively, the solid content of the nano-modified sludge-based material ethanol dispersion in S5 is 14wt%, and the solid content of the zinc oxide nanoparticle ethanol dispersion is 4wt%, then mix the two dispersions and continue ultrasonic dispersion treatment, the nano-modified sludge-based material ethanol dispersion and the zinc oxide nanoparticle ethanol dispersion are mixed in a weight ratio of 4:1, after sufficient dispersion, centrifugal separation, and drying, to obtain the nano-modified sludge-based reinforcement material;

[0050] S6. Wastewater treatment: Mix the nano-modified sludge-based reinforcement material with the wastewater with excessive heavy metal content in a weight ratio of 0.012:1. After mixing, react under stirring conditions for 11 hours, and centrifuge. The separated solid material is used to treat the next batch of wastewater with excessive heavy metal content and recycled. The separated liquid is the water with standard heavy metal content.

[0051] Example 4

[0052] A method for solidifying and recycling arsenic-containing sludge, comprising the following steps:

[0053] S1. Sludge pretreatment: The arsenic-containing sludge is taken out from the oxidation pond and placed in a drying device (blast drying oven) at a temperature of 105°C. After drying to constant weight, the sludge is taken out and crushed using a crusher and passed through a 60-mesh sieve. The powder after sieving is the pretreated sludge powder, which is sealed and stored in a dry environment for standby use;

[0054] S2. Adding and mixing: Mix the sludge powder, nanoclay and phosphogypsum in a weight ratio of 3:0.5:1.2, first grind and mix them thoroughly using a grinding device, then add water and stir to obtain a dispersion, wherein the mass fraction of the sludge powder in the dispersion is 10.5%;

[0055] S3. Acidification: dilute sulfuric acid was added dropwise to the dispersion, the concentration of the dilute sulfuric acid was 1 mol / L, the pH of the dispersion was adjusted to 6, stirred for 2 h, solid-liquid separation was performed, and the separated solid was retained for standby use;

[0056] S4. Heat treatment: The separated solid was placed in a heating device, heated under a nitrogen atmosphere, and pyrolyzed. The heating rate in S4 was controlled at 12 ° C / min, heated to 500 ° C and maintained for 3 h of pyrolysis, and then naturally cooled to room temperature to obtain a nano-modified sludge-based material;

[0057] S5. Zinc oxide modification treatment: prepare nano-modified sludge-based material ethanol dispersion and zinc oxide nanoparticle ethanol dispersion respectively, the solid content of the nano-modified sludge-based material ethanol dispersion in S5 is 15wt%, and the solid content of the zinc oxide nanoparticle ethanol dispersion is 3wt%, then mix the two dispersions and continue ultrasonic dispersion treatment, the nano-modified sludge-based material ethanol dispersion and the zinc oxide nanoparticle ethanol dispersion are mixed in a weight ratio of 3.2:1, after fully dispersed, centrifugally separated and dried to obtain the nano-modified sludge-based reinforcement material;

[0058] S6. Wastewater treatment: Mix the nano-modified sludge-based reinforcement material with wastewater with excessive heavy metal content in a weight ratio of 0.015:1. After mixing, react under stirring conditions for 10 hours, and centrifuge. The separated solid material is used to treat the next batch of wastewater with excessive heavy metal content and recycled. The separated liquid is the water with standard heavy metal content.

[0059] After testing, it was found that the method provided by the present invention can very effectively solidify the arsenic element in arsenic-containing sludge, and the obtained nano-modified sludge-based reinforcing material can be effectively adsorbed and removed from the sewage after being put into the sewage with excessive heavy metal content in proportion, thereby achieving the effect of treating pollution with waste.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for solidifying and recycling arsenic-containing sludge, characterized in that: The steps include: S1. Sludge pretreatment: The arsenic-containing sludge is taken out from the oxidation pond and placed in a drying device. After drying to constant weight, it is taken out, crushed and sieved. The sieved powder is the pretreated sludge powder, which is sealed and stored in a dry environment for standby use; S2. Adding and mixing: After mixing the sludge powder, nanoclay and phosphogypsum in proportion, adding water and stirring to obtain a dispersion; S3. Acidification: Add dilute sulfuric acid to the dispersion, adjust the pH of the dispersion to 5-6, stir for 0.5-2h, separate the solid and liquid, and retain the separated solid for later use; S4. Heat treatment: placing the separated solid in a heating device, heating it under a nitrogen atmosphere to pyrolyze it, and obtaining a nano-modified sludge-based material; S5. zinc oxide modification treatment: preparing a nano-modified sludge-based material ethanol dispersion and a zinc oxide nanoparticle ethanol dispersion respectively, and then mixing the two dispersions and continuing ultrasonic dispersion treatment, after sufficient dispersion, centrifugation and drying, to obtain a nano-modified sludge-based reinforcement material; S6. Wastewater treatment: Mix the nano-modified sludge-based reinforcement material with wastewater with excessive heavy metal content in proportion, stir to fully react, and then centrifuge. The separated solid material is used to treat the next batch of wastewater with excessive heavy metal content and recycled. The separated liquid is the water with standard heavy metal content.

2. The method for solidifying and recycling arsenic-containing sludge according to claim 1, characterized in that: The drying temperature in S1 is controlled at 100-105°C, and the dried material is crushed using a crusher and sieved using a 60-mesh screen.

3. The method for solidifying and recycling arsenic-containing sludge according to claim 1, characterized in that: The sludge powder, nanoclay and phosphogypsum in S2 are mixed in a weight ratio of 3:0.5-1:0.8-1.

2.

4. The method for solidifying and recycling arsenic-containing sludge according to claim 3 is characterized in that: After the sludge powder, nanoclay and phosphogypsum in S2 are mixed, they are first ground and mixed thoroughly using a grinding device.

5. The method for solidifying and recycling arsenic-containing sludge according to claim 3 is characterized in that: The mass fraction of the sludge powder in the dispersion obtained by S2 is 6.5-10.5%.

6. The method for solidifying and recycling arsenic-containing sludge according to claim 1, characterized in that: The concentration of the dilute sulfuric acid added dropwise in S3 is 1-2 mol / L.

7. The method for solidifying and recycling arsenic-containing sludge according to claim 1, characterized in that: In S4, the heating rate is controlled at 8-12°C / min, and after heating to 500°C, it is maintained for 2-3h and then naturally cooled to room temperature.

8. The method for solidifying and recycling arsenic-containing sludge according to claim 1, characterized in that: The solid content of the nano-modified sludge-based material ethanol dispersion in S5 is 10-15wt%, and the solid content of the zinc oxide nanoparticle ethanol dispersion is 3-6wt%.

9. The method for solidifying and recycling arsenic-containing sludge according to claim 8, characterized in that: In S5, the nano-modified sludge-based material ethanol dispersion and the zinc oxide nanoparticle ethanol dispersion are mixed in a weight ratio of 3.2-6.4:

1.

10. The method for solidifying and recycling arsenic-containing sludge according to any one of claims 1 to 9, characterized in that: The nano-modified sludge-based reinforcing material is mixed with sewage with excessive heavy metal content in a weight ratio of 0.005-0.015:1, and reacted for 10-15 hours under stirring conditions after mixing.