CN115448564A - Municipal sludge soil treatment method - Google Patents
Municipal sludge soil treatment method Download PDFInfo
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- CN115448564A CN115448564A CN202210965649.1A CN202210965649A CN115448564A CN 115448564 A CN115448564 A CN 115448564A CN 202210965649 A CN202210965649 A CN 202210965649A CN 115448564 A CN115448564 A CN 115448564A
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- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical class O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 2
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-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/10—Treatment of sludge; Devices therefor by pyrolysis
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
- C05F7/00—Fertilisers from waste water, sewage sludge, sea slime, ooze or similar masses
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Treatment Of Sludge (AREA)
- Fertilizers (AREA)
Abstract
The invention provides a municipal sludge soil treatment method, which comprises the following steps: A. pretreating sludge to be treated to obtain slurry sludge; B. sending the sludge in the slurry state into a hydrothermal reactor for hydrothermal reaction; the reaction temperature is 130-140 ℃, and the reaction time is 30-60 min; C. feeding the sludge after the hydrothermal reaction into a hydrothermal oxidation reactor, and introducing air to enable the sludge and oxygen to perform hydrothermal oxidation reaction; the oxidation temperature is 180-220 ℃, the oxygen concentration is 0.5-2 ppm, and the oxidation reaction time is 15-20 min; D. conveying the sludge after the hydrothermal oxidation reaction into a flash evaporation container for decompression flash evaporation; E. carrying out solid-liquid separation on the sludge discharged from the flash evaporation container to obtain dewatered sludge; F. crushing the dewatered sludge, and mixing a composite soil conditioner in a crushed product to obtain nutrient soil; the invention combines hydrothermal reaction and hydrothermal oxidation reaction, effectively reduces the content of refractory organic matters, promotes the generation of humus, and ensures the quality of the nutrient soil.
Description
Technical Field
The invention relates to the field of sludge treatment, in particular to a municipal sludge soil treatment method.
Background
With the development of urbanization and the expansion of the scale of sewage treatment plants, the yield of sludge consisting of microbial micelles, organic matters, inorganic particles and water generated in the sewage treatment process is gradually increased, and secondary pollution to the environment is easily caused. However, the sludge is considered as a potential and available energy resource due to the characteristics of high organic matter content, rich nutrient elements and the like. Therefore, the sludge treatment aims to realize reduction, stabilization and harmlessness of the sludge, encourage the recovery and utilization of resources in the sludge, and realize the treatment and utilization of the sludge on the premise of environmental protection, safety and economy.
The sludge soil formation is an important means for realizing resource saving and environmental protection, and the sludge is processed into a product with the property of ecological soil by conditioning technologies such as chemistry, physics, biology and the like, so that the product has the characteristics of water retention and fertilizer retention, has certain porosity and is suitable for soil microorganisms and plant growth. CN106587572B (sludge soil chemical treatment process of urban sewage plant and sludge prepared by the process and sludge application) adopts a chemical treatment method, and a composite oxidant and a composite dehydrating agent are added into sludge to realize sterilization and dehydration of the sludge, but the added agents in the method are mainly inorganic agents, the addition amount of the agents is 10-17% of dry basis, and the reduction of the sludge is not facilitated; in addition, the sludge treatment time is long, which is not beneficial to realizing the rapid recycling of the sludge; patent CN110463563B (a method for improving the soil of a mixture of industrial solid waste and sludge by using modified montmorillonite) provides a method for conditioning sludge to make the sludge into soil by using modified montmorillonite, phosphogypsum, carbide slag and the like, but the method is suitable for river and lake bottom sludge and cannot play a role in stabilizing organic matters for sewage plant sludge with high organic matter content; in addition, the method has long reaction time and is not beneficial to realizing the rapid recycling of the sludge.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a municipal sludge soil treatment method, which can quickly promote the disintegration and reduction of sludge and realize the stabilization of sludge so as to meet the subsequent production requirement of nutrient soil.
The invention is realized by the following technical scheme:
the invention provides a municipal sludge soil treatment method, which comprises the following steps:
A. sending sludge to be treated into a preprocessor for preprocessing so as to obtain slurried sludge; the water content of the slurried sludge is 85-90%, and the temperature of the slurried sludge is 80-90 ℃;
B. sending the slurried sludge into a hydrothermal reactor for hydrothermal reaction to obtain a hydrolysate; the temperature of the hydrothermal decomposition reaction is 130-140 ℃, and the reaction time is 30-60 min;
C. feeding the hydrolysate into a hydrothermal oxidation reactor, and introducing air to enable sludge and oxygen to perform low-oxygen hydrothermal reaction in the hydrothermal oxidation reactor to obtain a hydrothermal oxidation product; the oxidation temperature is 180-220 ℃, the oxidation pressure is 1.5 Mpa-5 MPa, the oxygen concentration is 0.5 ppm-2 ppm, and the oxidation reaction time is 15 min-20 min;
D. feeding the hydrothermal oxidation product into a flash evaporation container for decompression flash evaporation to obtain residual sludge;
E. carrying out solid-liquid separation on the excess sludge discharged from the flash evaporation container to obtain dewatered sludge;
F. and (3) crushing the dewatered sludge to obtain a crushed product with the particle size not larger than 1cm, and mixing the crushed product with a composite soil conditioner to obtain the nutrient soil.
In some embodiments of the invention, the composite soil conditioner comprises a water soluble biomass and a soil bulking agent; the adding amount of the water-soluble biomass accounts for 0.5-2% of the mass of the sludge to be mixed and dewatered; the water-soluble biomass is carboxymethyl cellulose, chitosan or galactomannan; the soil loosening agent accounts for 5-10% of the mass of the dewatered sludge to be mixed.
In some embodiments of the invention, the soil loosening agent is a mixture of wood chips and dried leaves, and the weight ratio of the wood chips to the dried leaves is 1:10 to 20.
In some embodiments of the invention, the liquid separated in step E is returned to the preheating reactor to be mixed with the sludge to be treated, the water content of the sludge is adjusted to 85% to 90%, and the sludge to be treated is preheated.
In some embodiments of the present invention, the flash vapor obtained by the reduced pressure flash evaporation in the step D is recycled to the preheating reactor to be mixed with the sludge to be treated, so as to preheat the sludge to be treated.
In some embodiments of the invention, the pretreatment in step a comprises stirring the sludge.
Compared with the prior art, the technical scheme of the invention has the following advantages:
according to the method, microbial cells in the sludge are broken through a hydrothermal reaction to release intracellular water, sludge flocs are destroyed, and organic matters in the sludge are dissolved out and partially hydrolyzed, so that macromolecular organic matters such as protein and compound carbohydrate are hydrolyzed to generate micromolecular organic matters such as reducing sugar, amino acid, organic acid and nitrite and polyphenol substances; because the hydrothermal reaction temperature is low, the dehydration polymerization of reducing sugar and amino acid is not facilitated to generate the organic matter which is difficult to degrade and is in the form of sugar aldehyde, the generation of the organic matter which is difficult to degrade and is in the form of sugar aldehyde is effectively reduced, and the concentration of the small molecular organic matter in the sludge is improved; on one hand, the arrangement of the low-oxygen hydrothermal reaction further oxidizes and degrades furfural refractory organic matters generated by the hydrothermal reaction so as to avoid influencing the growth of soil microorganisms and plants; on the other hand, the polyphenols are oxidized and condensed with nitrogen-containing compounds to generate humus beneficial to soil ecology, and meanwhile, perishable organic matters are oxidized and stabilized, so that the organic matter content of the sludge is ensured (namely, the sludge is ensured to contain enough nutrient substances); because oxidation reaction can release a large amount of heat, the device not only can supply heat for self reaction, save energy consumption of a system, but also can effectively kill harmful organisms such as viruses, germs, parasites and the like; the combination of the hydrothermal reaction and the low-oxygen hydrothermal reaction effectively improves the sludge dewatering effect, realizes sludge reduction and simultaneously ensures the stability of sludge nutrient substances;
through hydrothermal reaction and low-oxygen hydrothermal oxidation reaction, organic matters in the sludge are fully hydrolyzed and stabilized, the dehydration performance is greatly improved, the dehydrated sludge is dry, odorless, loose in structure and reduced in viscosity, the water-soluble biomass with viscosity and a soil loosening agent are used for adjusting the porosity and the mechanical properties among particles of the dehydrated sludge, the self-adjusting and self-adapting capabilities of the dehydrated sludge on humidity and temperature are improved, the dehydrated sludge becomes nutrient soil with good water and fertilizer retention effects, the microbial growth suitability and the ecological function, and the resource utilization of the sludge is realized.
Drawings
FIG. 1 is a process flow diagram of the municipal sludge soil treatment method of the invention.
Detailed Description
The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.
Before the present embodiments are further described, it is to be understood that the scope of the invention is not limited to the particular embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.
When numerical ranges are given in the examples, it is understood that both endpoints of each of the numerical ranges and any value therebetween can be selected unless the invention otherwise indicated. Unless otherwise defined, any methods, devices, and materials similar or equivalent to those described in embodiments of the invention, in addition to the specific methods, devices, and materials used in the invention, may be used in the practice of the invention in light of the knowledge of one skilled in the art and the description of the present invention.
As shown in figure 1, the municipal sludge soil treatment method comprises the following steps:
A. sending sludge to be treated into a preprocessor for preprocessing so as to obtain homogeneous slurried sludge; the water content of the slurried sludge is 85-90%, and the temperature of the slurried sludge is 80-90 ℃;
further, the pre-treatment step comprises sludge pre-heating and/or sludge agitation to slurry the sludge into a homogeneous fluid state (i.e., to obtain a homogeneous slurry-state sludge); the sludge is preheated by using the recovered hot steam and/or the separated hot filtrate so as to heat the sludge to 80-90 ℃.
B. B, feeding the sludge in the slurry state in the step A into a hydrothermal reactor for hydrothermal decomposition reaction; the temperature of the hydrothermal decomposition reaction is 130-140 ℃, and the reaction time is 30-60 min;
through hydrothermal reaction, organic matters in the sludge are dissolved out and partially hydrolyzed, macromolecular organic matters such as protein and complex carbohydrate are hydrolyzed to generate micromolecular organic matters such as reducing sugar, amino acid, organic acid and nitrite and polyphenol substances, and the content of free water is increased; meanwhile, the hydrolysis temperature is low, so that the method is not beneficial to the dehydration polymerization of reducing sugar and amino acid to generate the organic matter which is difficult to degrade and is in the glucal class, the generation of the organic matter which is difficult to degrade and is in the glucal class is effectively reduced, and the concentration of the small molecular organic matter in the sludge is improved.
C. B, conveying the sludge subjected to the hydrothermal reaction in the step B into a hydrothermal oxidation reactor, and introducing air to enable the sludge and oxygen to perform low-oxygen hydrothermal reaction in the hydrothermal oxidation reactor; the oxidation temperature is 180-220 ℃, the oxidation pressure is 1.5-5 MPa, the oxygen concentration is 0.5-2 ppm, and the oxidation reaction time is 15-20 min;
in the low-oxygen hydrothermal reaction, on one hand, furfural refractory organic matters generated by the hydrothermal reaction are further subjected to oxidative degradation so as to avoid influencing the growth of soil microorganisms and plants; on the other hand, the polyphenol substances are condensed with nitrogen-containing compounds after being oxidized to generate humus beneficial to soil ecology, so that the oxidation stability of organic matters is realized, and sufficient nutrient substances in solid products are ensured; in addition, a large amount of heat is released by the oxidation reaction, and the energy consumption of the system can be effectively reduced.
D. C, conveying the sludge subjected to the low-oxygen hydrothermal reaction in the step C into a flash evaporation container for reduced pressure flash evaporation;
the sludge is boiled and vaporized in the flash evaporation container rapidly to realize vapor-liquid separation, and the separated hot steam can be recycled to the preprocessor for sludge preheating.
E. Carrying out solid-liquid separation on the sludge discharged from the flash evaporation container to obtain dewatered sludge;
and various solid-liquid separation devices such as a plate-and-frame filter press, a centrifugal dehydrator, a spiral-stacked dehydrator, a belt dehydrator and the like can be adopted to perform solid-liquid separation on the sludge discharged from the flash evaporation container to obtain hot filtrate and dehydrated sludge with the water content not higher than 50%, one part of the hot filtrate can flow back to a preprocessor to perform sludge preheating and sludge water content blending, and the other part of the hot filtrate flows back to a sewage plant to be treated and then is discharged.
F. And crushing the dewatered sludge to obtain a crushed product with the particle size of not more than 1cm, and mixing the crushed product with a composite soil conditioner to obtain the nutrient soil.
The composite soil conditioner comprises a water-soluble biomass solution and a soil loosening agent; the adding amount of the water-soluble biomass accounts for 0.5-2% of the mass of the sludge to be mixed and dewatered; the water-soluble biomass is carboxymethyl cellulose, chitosan and/or galactomannan; the mass of the soil loosening agent accounts for 5% -10% of the mass of the dewatered sludge to be mixed, and the soil loosening agent is a mixture of sawdust and dried withered leaves, wherein the weight ratio of the sawdust to the dried withered leaves is 1:10 to 20.
It will be appreciated that when the water-soluble biomass is galactomannan, guar gum is preferably used for the galactomannan.
The following are descriptions of specific embodiments:
example one
A municipal sludge soil treatment method comprises the following steps:
A. 1kg of sewage plant dewatered sludge with the water content of 81 percent and the organic matter content of 47.2 percent is sent into a preprocessor to be mixed and stirred with water into sludge with the water content of 87 percent, then the mixed sludge is preheated and pulped through recycled flash steam to obtain pulped sludge, and the temperature of the pulped sludge is 90 ℃;
B. sending the slurried sludge into a hydrothermal reactor for hydrothermal reaction to obtain a hydrolysate; the reaction temperature is 130 ℃, and the reaction time is 30min; the hydrolysate contains a large amount of micromolecular water-soluble organic matters such as reducing sugar, various amino acids, organic acid and the like which are easy to be absorbed by plants, polyphenol substances and a small amount of organic matters which are difficult to degrade such as glucal;
C. feeding the hydrolysate into a hydrothermal oxidation reactor, and introducing air into the hydrothermal oxidation reactor to perform low-oxygen hydrothermal reaction to obtain a hydrothermal oxidation product; the oxygen concentration in the reactor is 1ppm, the reaction temperature is 180 ℃, the reaction pressure is 1.5Mpa, and the reaction time is 15min, so that the furfural refractory organic matters are further oxidized and degraded, and the polyphenols are oxidized and then condensed with nitrogen-containing compounds to generate humus beneficial to soil ecology;
D. feeding the hydrothermal oxidation product into a flash evaporation container for flash evaporation and pressure relief to obtain flash evaporation steam and excess sludge; the obtained flash steam flows back to a preprocessor to preheat sludge;
E. carrying out solid-liquid separation on the excess sludge through a solid-liquid separation device to obtain dewatered sludge; the obtained dewatered sludge weighs 0.25kg, the water content is 38 percent, and the total mass reduction rate of the sludge is 75 percent;
F. crushing the dewatered sludge to obtain a dry crushed product which has no obvious odor and is in a fine particle state; the particle size of the crushed product is uniform and is not more than 1cm; uniformly mixing 2.5g of carboxymethyl cellulose with the crushed dewatered sludge, spraying a small amount of water to completely fuse the mixture, and simultaneously adding 20g of sawdust and dried leaves mixture to obtain nutrient soil; wherein the mass ratio of the wood chips to the dried leaves is about 1:10; the organic matter content of the nutrient soil is 37%, the nutrient soil is dark brown, the structure is soft and light, the saturated water content is 58.9%, the EC value is 156mS/m, the water content is 39.2%, and the germination index of seeds is 98%.
Example two
A municipal sludge soil treatment method comprises the following steps: A. 1kg of sewage plant dewatered sludge with the water content of 85 percent and the organic matter content of 43.9 percent is sent into a preprocessor and stirred, and preheated and pulped through recovered flash steam to obtain pulped sludge, wherein the temperature of the pulped sludge is 90 ℃;
B. feeding the slurried sludge into a hydrothermal reactor for hydrothermal reaction to obtain a hydrolysate; the reaction temperature is 140 ℃, and the reaction time is 30min; the hydrolysate contains a large amount of micromolecular water-soluble organic matters such as reducing sugar, various amino acids, organic acid and the like which are easy to be absorbed by plants, polyphenol substances and a small amount of organic matters which are difficult to degrade in glucide;
C. feeding the hydrolysate into a hydrothermal oxidation reactor, and introducing air into the hydrothermal oxidation reactor to perform low-oxygen hydrothermal reaction to obtain a hydrothermal oxidation product; the oxygen concentration in the reactor is 1ppm, the reaction temperature is 200 ℃, the reaction pressure is 2Mpa, and the reaction time is 15min, so that the furfural refractory organic matters are further oxidized and degraded, and the polyphenol substances are oxidized and then condensed with nitrogen-containing compounds to generate humus beneficial to soil ecology;
D. feeding the hydrothermal oxidation product into a flash evaporation container for flash evaporation and pressure relief to obtain flash evaporation steam and excess sludge; the obtained flash steam flows back to a preprocessor to preheat sludge;
E. carrying out solid-liquid separation on the excess sludge through a solid-liquid separation device to obtain dewatered sludge; the obtained dewatered sludge weighs 0.19kg, the water content is 35 percent, and the mass total reduction rate of the sludge is 81 percent;
F. crushing the dewatered sludge to obtain a dry crushed product which has no obvious odor and is in a fine particle state, wherein the particle size of the crushed product is uniform and is not more than 1cm; uniformly mixing 2.85g of chitosan and crushed dewatered sludge, spraying a small amount of water to completely fuse the chitosan and the crushed dewatered sludge, and simultaneously adding 15g of sawdust and dried leaves mixture to obtain nutrient soil; wherein the mass ratio of the wood chips to the dried leaves is about 1:15; the organic matter content of the nutrient soil is 31%, the nutrient soil is dark brown, the structure is soft and light, the saturated water content is 62.1%, the EC value is 200mS/m, the water content is 35%, and the germination index of seeds is 110%.
EXAMPLE III
A municipal sludge soil treatment method comprises the following steps:
A. 5kg of sewage plant dewatered sludge with the water content of 85 percent and the organic matter content of 52 percent is conveyed into a preprocessor, stirred and preheated to pulp through recovered flash steam at the same time to obtain pulped sludge, and the temperature of the pulped sludge is 86 ℃;
B. sending the slurried sludge into a hydrothermal reactor for hydrothermal reaction to obtain a hydrolysate; the reaction temperature is 120 ℃, and the reaction time is 60min; the hydrolysate contains a large amount of micromolecular water-soluble organic matters such as reducing sugar, various amino acids, organic acid and the like which are easy to be absorbed by plants, polyphenol substances and a small amount of organic matters which are difficult to degrade in glucide;
C. feeding the hydrolysate into a hydrothermal oxidation reactor, and introducing air into the hydrothermal oxidation reactor to perform low-oxygen hydrothermal reaction to obtain a hydrothermal oxidation product; the oxygen concentration in the reactor is 2ppm, the reaction temperature is 200 ℃, the reaction pressure is 2.5Mpa, the reaction time is 20min, so as to further oxidize and degrade the difficultly degraded organic matters of furfural, and the polyphenols are oxidized and then condensed with nitrogen-containing compounds to generate humus beneficial to soil ecology;
D. feeding the hydrothermal oxidation product into a flash evaporation container for flash evaporation and pressure relief to obtain flash evaporation steam and excess sludge; the obtained flash steam flows back to a preprocessor to preheat sludge;
E. carrying out solid-liquid separation on the excess sludge through a solid-liquid separation device to obtain dewatered sludge; the obtained dewatered sludge weighs 1.1kg, the water content is 32 percent, and the total mass reduction rate of the sludge is 78 percent;
F. crushing the dewatered sludge to obtain a dry crushed product which has no obvious odor and is in a fine particle state, wherein the particle size of the crushed product is uniform and is not more than 1cm; fully mixing 15g of guar gum with the crushed dewatered sludge, spraying a small amount of water to fully fuse the guar gum and the crushed dewatered sludge, and simultaneously adding 60g of wood chips and dried leaves to obtain nutrient soil; wherein the mass ratio of the wood chips to the dried leaves is about 1:10; the organic matter content of the nutrient soil is 36.7%, the nutrient soil is dark brown, the structure is soft and light, the saturated water content is 68.9%, the EC value is 174mS/m, the water content is 31.2%, and the germination index of seeds is 107%.
In conclusion, the municipal sludge soil treatment method disclosed by the invention combines hydrothermal reaction and hydrothermal oxidation reaction, so that organic matters are fully hydrolyzed, the content of refractory organic matters is effectively reduced, the sludge dewatering performance is improved, the generation of humus is promoted, the stabilization of sludge is accelerated, the physical shape of dewatered sludge is further improved through soluble biomass and a soil conditioner, the dewatered sludge becomes nutrient soil with water and fertilizer retention effects, and the municipal sludge is recycled.
While the invention has been described in terms of preferred embodiments, it will be apparent to those skilled in the art that the techniques of the invention can be practiced with modification, or with appropriate modification and combination, of the techniques described herein without departing from the spirit, scope and spirit of the invention. It is expressly intended that all such similar substitutes and modifications which would be obvious to those skilled in the art are deemed to be within the spirit, scope and content of the invention.
Claims (6)
1. The municipal sludge soil treatment method is characterized by comprising the following steps:
A. sending sludge to be treated into a preprocessor for preprocessing so as to obtain slurried sludge; the water content of the slurried sludge is 85-90%, and the temperature of the slurried sludge is 80-90 ℃;
B. sending the slurried sludge into a hydrothermal reactor for hydrothermal reaction to obtain a hydrolysate; the temperature of the hydrothermal decomposition reaction is 130-140 ℃, and the reaction time is 30-60 min;
C. feeding the hydrolysate into a hydrothermal oxidation reactor, and introducing air to enable sludge and oxygen to perform low-oxygen hydrothermal reaction in the hydrothermal oxidation reactor to obtain a hydrothermal oxidation product; the oxidation temperature is 180-220 ℃, the oxidation pressure is 1.5-5 MPa, the oxygen concentration is 0.5-2 ppm, and the oxidation reaction time is 15-20 min;
D. feeding the hydrothermal oxidation product into a flash evaporation container for decompression flash evaporation to obtain residual sludge;
E. carrying out solid-liquid separation on the excess sludge discharged from the flash evaporation container to obtain dewatered sludge;
F. and crushing the dewatered sludge to obtain a crushed product with the particle size of not more than 1cm, and mixing the crushed product with a composite soil conditioner to obtain the nutrient soil.
2. The municipal sludge agrinization method according to claim 1, wherein the composite soil conditioner comprises water-soluble biomass and a soil loosening agent; the adding amount of the water-soluble biomass accounts for 0.5-2% of the mass of the sludge to be mixed and dewatered; the water-soluble biomass is carboxymethyl cellulose, chitosan or galactomannan; the soil loosening agent accounts for 5-10% of the mass of the dewatered sludge to be mixed.
3. The municipal sludge agroforestry treatment method according to claim 2, wherein the soil loosening agent is a mixture of wood chips and dried leaves, and the weight ratio of the wood chips to the dried leaves is 1:10 to 20.
4. The method of claim 1, wherein the separated liquid from step E is returned to the pre-heating reactor to mix with the sludge to be treated, adjust the water content of the sludge to 85% to 90%, and pre-heat the sludge to be treated.
5. The municipal sludge soil treatment method according to claim 1 or 4, wherein the flash steam obtained by the reduced pressure flash evaporation in the step D is recycled to the preheating reactor and mixed with the sludge to be treated to preheat the sludge to be treated.
6. The method for treating the soil of municipal sludge according to claim 1 or 4, wherein the pretreatment in step A comprises stirring the sludge.
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Application publication date: 20221209 |