CN113896402A - Sludge dewatering method - Google Patents
Sludge dewatering method Download PDFInfo
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- CN113896402A CN113896402A CN202111177063.0A CN202111177063A CN113896402A CN 113896402 A CN113896402 A CN 113896402A CN 202111177063 A CN202111177063 A CN 202111177063A CN 113896402 A CN113896402 A CN 113896402A
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- 239000010802 sludge Substances 0.000 title claims abstract description 141
- 238000000034 method Methods 0.000 title claims abstract description 44
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 109
- 239000007800 oxidant agent Substances 0.000 claims abstract description 39
- 239000002253 acid Substances 0.000 claims abstract description 36
- 230000001590 oxidative effect Effects 0.000 claims abstract description 28
- 238000002156 mixing Methods 0.000 claims description 41
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 18
- 239000007788 liquid Substances 0.000 claims description 18
- 238000003756 stirring Methods 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 14
- 238000011085 pressure filtration Methods 0.000 claims description 10
- 238000000926 separation method Methods 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- 229910017604 nitric acid Inorganic materials 0.000 claims description 4
- 150000002978 peroxides Chemical class 0.000 claims description 3
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 3
- 230000018044 dehydration Effects 0.000 abstract description 18
- 238000006297 dehydration reaction Methods 0.000 abstract description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 20
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 17
- 208000005156 Dehydration Diseases 0.000 description 15
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 15
- 239000007787 solid Substances 0.000 description 12
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 9
- 238000001914 filtration Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 239000002245 particle Substances 0.000 description 7
- 238000009777 vacuum freeze-drying Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 238000005189 flocculation Methods 0.000 description 6
- 230000016615 flocculation Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 4
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011258 core-shell material Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 230000014509 gene expression Effects 0.000 description 2
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 150000003254 radicals Chemical class 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- -1 sulfate radical Chemical class 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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Classifications
-
- 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
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
- C02F11/143—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances
-
- 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
- C02F11/06—Treatment of sludge; Devices therefor by oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/02—Specific form of oxidant
- C02F2305/026—Fenton's reagent
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention belongs to the technical field of sludge treatment, and particularly relates to a sludge dewatering method. According to the invention, the original zero-valent iron and the acid solution are mixed and heated, so that the dehydration performance of the sludge can be improved, the sludge dehydration efficiency of the sludge and the oxidant can be improved, and the deep dehydration of the sludge can be realized.
Description
Technical Field
The invention belongs to the technical field of sludge treatment, and particularly relates to a sludge dewatering method.
Background
Sludge dewatering refers to a sludge treatment method for removing water from fluid primary sludge and concentrated sludge and converting the sludge into semi-solid or solid sludge blocks. Due to the characteristic of combination of water and sludge particles, mechanical removal has certain limitation, only sludge with 20-30% of solid content can be obtained, and the sludge still has fluidity and is high in treatment difficulty and cost.
The adoption of zero-valent iron combined with an oxidant for sludge dehydration is one of the novel methods at present, and is beneficial to destroying the structure of sludge, thereby achieving the dehydration effect. However, the dewatering efficiency of the process still remains to be improved.
Disclosure of Invention
The invention aims to provide a sludge dewatering method, and aims to solve the technical problem of low dewatering efficiency when the existing zero-valent iron is combined with an oxidant for sludge dewatering.
In order to achieve the above object, the present invention provides a sludge dewatering method, comprising the steps of:
providing raw zero-valent iron, an acid solution, an oxidant and sludge;
mixing and heating the original zero-valent iron and the acid solution, and performing solid-liquid separation to obtain modified zero-valent iron;
and mixing the modified zero-valent iron and the oxidant with the sludge, and dehydrating to obtain dehydrated sludge.
As a preferable embodiment of the method for dewatering stone sludge according to the present invention, the acid solution is at least one selected from dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.
As a preferable technical scheme of the sludge dewatering method, the concentration of the acid solution is 0.03-0.05 mol/L.
As a preferable technical scheme of the sludge dewatering method, in the step of mixing and heating the original zero-valent iron and the acid solution, the mass ratio of the zero-valent iron to the acid solution is 1 (8-10).
As a preferable technical scheme of the sludge dewatering method, the temperature of the mixing and heating treatment is 55-60 ℃, and the time is 10-30 min.
As a preferable technical scheme of the sludge dewatering method, the introduction flow rate of the gas carbon source is 0.5sccm-50 sccm.
As a preferable technical scheme of the sludge dewatering method, in the step of mixing the modified zero-valent iron and the oxidant with the sludge, the addition weight of the modified zero-valent iron accounts for 1-2 per mill of the dry weight of the sludge in the sludge.
As a preferable technical scheme of the sludge dewatering method, in the step of mixing the modified zero-valent iron and the oxidant with the sludge, the addition weight of the oxidant accounts for 0.4-0.5 per mill of the dry weight of the sludge in the sludge.
As a preferable technical scheme of the sludge dewatering method, in the step of mixing the modified zero-valent iron and the oxidant with the sludge, the stirring speed of the mixing treatment is 100rpm-150rpm, and the stirring time is 5min-10 min.
As a preferable technical scheme of the sludge dewatering method, the dewatering treatment is filter pressing for 10-20min under the condition of 4-5 MPa.
As a preferable embodiment of the sludge dewatering method of the present invention, the oxidizing agent is at least one selected from the group consisting of peroxides, persulfates, and permanganates.
The original zero-valent iron material has a core-shell structure, namely, the core is metallic iron, and a small amount of iron oxide is attached to the outer layer. The invention can react the iron oxide on the surface of the original zero-valent iron to generate Fe by mixing and heating the original zero-valent iron and the acid solution3+While the zero-valent iron core reacts with the acid solution to generate Fe2+To obtain the iron with different valence states (zero-valent iron and Fe)2+、Fe3+) The ferrite structure of (1). The modified zero-valent iron and oxidant are used for sludge dewatering, and on one hand, Fe generated by the reaction of iron oxide and acid solution3+And Fe generated by reaction of zero-valent iron core with acid solution2+All have flocculation effect, not only can change sludge particles into larger particles under the flocculation effect, but also can release Extracellular Polymeric Substances (EPS) in the sludge into liquid, thereby improving the sewageThe dewatering properties of the mud; on the other hand, Fe generated by reaction of zero-valent iron core with acid solution2+Is favorable for Fenton reaction with the oxidant and improves the sludge dewatering efficiency. Therefore, in the sludge dewatering method provided by the invention, the original zero-valent iron and the acid solution are mixed and heated, so that the dewatering performance of the sludge can be improved, the sludge dewatering efficiency of the sludge and the oxidant can be improved, and the deep dewatering of the sludge can be realized.
Drawings
Fig. 1 is a schematic diagram of a flow and a reaction mechanism of a sludge dewatering method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described, and the embodiments described below are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention. Those whose specific conditions are not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer; the reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the description of the present invention, the term "and/or" describing an association relationship of associated objects means that there may be three relationships, for example, a and/or B, may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the description of the present invention, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (a), b, or c", or "at least one (a), b, and c", may each represent: a. b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple respectively.
It should be understood that the weight of the related components mentioned in the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, it is within the scope of the disclosure that the content of the related components is scaled up or down according to the embodiments of the present invention. Specifically, the weight described in the embodiments of the present invention may be a unit of mass known in the chemical field such as μ g, mg, g, kg, etc.
In addition, unless the context clearly uses otherwise, an expression of a word in the singular is to be understood as including the plural of the word. The terms "comprises" or "comprising" are intended to specify the presence of stated features, quantities, steps, operations, elements, portions, or combinations thereof, but are not intended to preclude the presence or addition of one or more other features, quantities, steps, operations, elements, portions, or combinations thereof.
The embodiment of the invention provides a sludge dewatering method, which comprises the following steps:
s1, providing original zero-valent iron, an acid solution, an oxidant and sludge;
s2, mixing and heating the original zero-valent iron and an acid solution, and performing solid-liquid separation to obtain modified zero-valent iron;
and S3, mixing the modified zero-valent iron and the oxidant with the sludge, and dehydrating to obtain dehydrated sludge.
The existing theory holds that the spatial structure of extracellular polymeric substances is fixed EPS (B-EPS) and soluble EPS (S-EPS), wherein the fixed EPS is divided into a loosely adhered outer layer (LB-EPS) and a tightly adhered inner layer (TB-EPS). These extracellular polymers are composed of high molecular substances such as polysaccharides and proteins, and have high hydrophilic properties, so that it is difficult to completely separate solid from liquid in sludge. According to the embodiment of the invention, the original zero-valent iron and the acid solution are mixed and heated, so that the iron oxide on the surface of the original zero-valent iron can react to generate Fe3+While the zero-valent iron core reacts with the acid solution to generate Fe2+And obtaining the modified zero-valent iron. The modified zero-valent iron and oxidant are used for sludge dewatering, and on one hand, Fe generated by the reaction of iron oxide and acid solution3+And Fe generated by reaction of zero-valent iron core with acid solution2+The sludge has flocculation, so that not only can sludge particles become larger particles under the flocculation, but also Extracellular Polymeric Substances (EPS) in the sludge can be released into liquid, thereby improving the dehydration performance of the sludge; on the other hand, Fe generated by reaction of zero-valent iron core with acid solution2+Is favorable for Fenton reaction with the oxidant and improves the sludge dewatering efficiency. Therefore, the Fenton-like oxidation method provided by the embodiment of the invention is used for sludge dehydration treatment, and the original zero-valent iron and the acid solution are mixed and heated, so that the dehydration performance of the sludge can be improved, the sludge dehydration efficiency of the sludge and an oxidant can be greatly improved, and the deep dehydration of the sludge can be realized.
FIG. 1 shows the flow and reaction mechanism of the sludge dewatering method provided by the embodiment of the invention. Specifically, in S1, the original zero-valent iron (Pristine ZVI) has a core-shell structure, in which the core is metallic iron and the outer layer is coated with a layer of iron oxide.
The acid solution is used for modifying the original zero-valent iron in the embodiment of the invention, so that when the modified zero-valent iron is used together with the oxidant, the dehydration performance of the sludge is improved, and the dehydration efficiency of the sludge is improved. In some embodiments, the acid solution is selected from at least one of dilute sulfuric acid, dilute hydrochloric acid, dilute nitric acid, preferably dilute sulfuric acid, which is more prone to ferrous sulfate formation.
In some embodiments, a dilute sulfuric acid solution with a concentration of 0.03-0.05mol/L is selected to promote Fenton oxidation and provide electrons for sludge EPS removal.
The oxidant can react with zero-valent iron to generate Fenton-like oxidation reaction. The Fenton reaction is Fe2+Reacts with oxidant to generate a large amount of free radicals, and further initiates a series of free radical chain reactions. The oxidizing agent used in the embodiments of the present invention may be selected from oxidizing agents conventional in the art. In some embodiments, the oxidizing agent is selected from at least one of peroxides, persulfates, permanganates. These oxygen speciesThe oxidant has strong oxidizability and low cost, and is beneficial to reducing the cost of sludge dehydration and improving the dehydration efficiency.
In S2, the original zero-valent iron is modified by mixing and heating the original zero-valent iron with an acid solution (i.e., "hot acid treatment"), so that iron oxide on the surface of the original zero-valent iron reacts with the acid solution to generate Fe3+Reaction of zero-valent iron nuclei with acid solution to produce Fe2+. The obtained modified zero-valent iron (TAZVI) contains Fe0、Fe3+Fe2+. In some embodiments, in the step of mixing and heating the original zero-valent iron and the acid solution, the mass ratio of the zero-valent iron to the acid solution is 1 (8-10), and the sulfate energy and the Fe are maintained2+Ferrous sulfate is formed.
In some embodiments, when the original zero-valent iron and the acid solution are subjected to mixing and heating treatment, the temperature of the mixing and heating treatment is 55-60 ℃, the heating can improve the reaction efficiency, and accelerate the removal of the EPS sludge for 10-30 min.
And (3) mixing and heating the original zero-valent iron and an acid solution, and performing solid-liquid separation to obtain a solid which is modified zero-valent iron. The solid-liquid separation method can adopt the conventional method in the field, including but not limited to filtration, centrifugation and the like. In some embodiments, the solid-liquid separation further comprises a step of drying the modified zero-valent iron. In one embodiment, the modified zero-valent iron is vacuum freeze-dried at-60 ℃ for 24 hours, and the freeze-drying can avoid over-oxidation of the zero-valent iron.
In S3, in the process of mixing the modified zero-valent iron and the oxidant with the sludge, Fe in the modified zero-valent iron2+And Fe3+The flocculant has flocculation effect, not only can change sludge particles into larger particles under the flocculation effect, but also can release extracellular polymers in the sludge into liquid, thereby effectively reducing the content of the extracellular polymers in the sludge, improving the dehydration performance of the sludge and promoting the dehydration effect after the oxidant is added. At the same time, Fe2+Generating Fe by Fenton reaction with oxidant3+The mixture of the sludge and hydroxyl, sulfate radical or manganese dioxide acts on the sludge to realize the high-efficiency dehydration of the sludge. Fe2+The reaction formula of Fenton reaction with the oxidant is as follows:
Fe2++ oxidant (H)2O2、S2O8 2-、MnO4 -)→Fe3++(·OH、SO4 -、MnO2)
In some embodiments, the added weight of the modified zero valent iron is 1% o to 2% o of the dry weight of the sludge in the sludge.
In some embodiments, the added weight of the oxidizing agent is 0.4% o to 0.5% o of the dry weight of the sludge in the sludge.
In some embodiments, in the step of mixing the modified zero-valent iron and the oxidant with the sludge, the stirring speed of the mixing process is 100rpm to 150rpm, and the stirring time is 5min to 10 min.
In some embodiments, the dehydration treatment is ultra high pressure filter pressing for 10-20min under the condition of 4-5 MPa.
In order to make the above implementation details and operation of the present invention clearly understood by those skilled in the art and to make the progress of the sludge dewatering method obvious in the embodiments of the present invention, the above technical solution is illustrated by the following examples.
Example 1
The embodiment provides a sludge dewatering method, which comprises the following steps:
(11) mixing nano original zero-valent iron with 0.05M dilute sulfuric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(12) adding 1mg/g sludge dry weight modified zero-valent iron and 0.4mg/g sludge dry weight hydrogen peroxide into concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(13) and carrying out pressure filtration for 10min under the ultrahigh pressure of 5MPa to obtain the dewatered sludge with the water content of 45%.
Example 2
The embodiment provides a sludge dewatering method, which comprises the following steps:
(21) mixing nano original zero-valent iron with 0.05M dilute sulfuric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(22) adding 2mg/g of modified zero-valent iron and 0.5mg/g of hydrogen peroxide into the concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(23) and (4) carrying out pressure filtration for 10min under the ultrahigh pressure of 4MPa to obtain the dewatered sludge with the water content of 47%.
Example 3
The embodiment provides a sludge dewatering method, which comprises the following steps:
(31) mixing nano original zero-valent iron with 0.05M dilute sulfuric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(32) adding 2mg/g of modified zero-valent iron and 0.5mg/g of hydrogen peroxide into the concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(33) and carrying out pressure filtration for 10min under the ultrahigh pressure of 5MPa to obtain the dewatered sludge with the water content of 42%.
Example 4
The embodiment provides a sludge dewatering method, which comprises the following steps:
(41) mixing nano original zero-valent iron with 0.05M dilute sulfuric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(42) adding 2mg/g of modified zero-valent iron and 0.6mg/g of hydrogen peroxide into the concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(43) and carrying out pressure filtration for 10min under the ultrahigh pressure of 5MPa to obtain the dewatered sludge with the water content of 42%.
Example 5 (modified to comparative example or not)
The embodiment provides a sludge dewatering method, which comprises the following steps:
(51) mixing nano original zero-valent iron with 0.05M dilute hydrochloric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(52) adding 2mg/g of modified zero-valent iron and 0.5mg/g of hydrogen peroxide into the concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(53) and carrying out pressure filtration for 10min under the ultrahigh pressure of 5MPa to obtain the dewatered sludge with the water content of 50%.
Example 6 (modified to comparative example or not)
The embodiment provides a sludge dewatering method, which comprises the following steps:
(61) mixing nano original zero-valent iron with 0.05M dilute nitric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(62) adding 2mg/g of modified zero-valent iron and 0.5mg/g of hydrogen peroxide into the concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(63) and carrying out pressure filtration for 10min under the ultrahigh pressure of 5MPa to obtain the dewatered sludge with the water content of 48%.
Comparative example 1
The comparative example provides a sludge dewatering method comprising the steps of:
(71) adding 1mg/g sludge dry weight modified zero-valent iron and 0.4mg/g sludge dry weight hydrogen peroxide into concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(72) and (4) carrying out pressure filtration for 10min under the ultrahigh pressure of 4MPa to obtain the dewatered sludge with the water content of 55%.
Comparative example 2
(81) Mixing nano-original zero-valent iron with 0.05M citric acid solution according to a solid-to-liquid ratio of 1:9, shaking at 60 ℃ for 10min, filtering, and carrying out vacuum freeze drying on the obtained solid at-60 ℃ for 24h to obtain modified zero-valent iron;
(82) adding 1mg/g sludge dry weight modified zero-valent iron and 0.4mg/g sludge dry weight hydrogen peroxide into concentrated sludge with the water content of 96%, mixing, and stirring at 100rpm for 5 min;
(83) and (4) carrying out pressure filtration for 10min under the ultrahigh pressure of 4MPa to obtain the dewatered sludge with the water content of 56%.
Comparative example 3
(91) Adding 1mg/g of original zero-valent iron, 0.05M of citric acid solution and 0.4mg/g of hydrogen peroxide into concentrated sludge with the water content of 96%, wherein the mass ratio of the original zero-valent iron to the citric acid solution is 1:9, and stirring and reacting for 5min at 100 rpm;
(92) and (4) carrying out pressure filtration for 10min under the ultrahigh pressure of 4MPa to obtain the dewatered sludge with the water content of 55%.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The sludge dewatering method is characterized by comprising the following steps:
providing raw zero-valent iron, an acid solution, an oxidant and sludge;
mixing and heating the original zero-valent iron and the acid solution, and performing solid-liquid separation to obtain modified zero-valent iron;
and mixing the modified zero-valent iron and the oxidant with the sludge, and dehydrating to obtain dehydrated sludge.
2. The sludge dewatering method according to claim 1, wherein the acid solution is selected from at least one of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; and/or
The original zero-valent iron is nano original zero-valent iron.
3. The sludge dewatering method according to claim 1, wherein the acid solution has a concentration of 0.03-0.05 mol/L.
4. The sludge dewatering method according to claim 1, wherein in the step of subjecting the raw zero-valent iron and the acid solution to mixed heating treatment, the solid-liquid mass ratio of the zero-valent iron to the acid solution is 1 (8-10).
5. The sludge dewatering method according to claim 1, wherein the temperature of the mixing and heating treatment is 55-66 ℃ and the time is 10-30 min.
6. The sludge dewatering method according to claim 1, wherein in the step of mixing the modified zero-valent iron and the oxidizing agent with the sludge, the modified zero-valent iron is added in an amount of 1% o to 2% o by weight based on the dry weight of the sludge in the sludge.
7. The sludge dewatering method according to claim 1, wherein in the step of mixing the modified zero-valent iron and the oxidizing agent with the sludge, the oxidizing agent is added in an amount of 0.4 to 0.6% by weight based on the dry weight of the sludge in the sludge.
8. The sludge dewatering method according to any one of claims 1 to 7, wherein in the step of subjecting the modified zero-valent iron and the oxidizing agent to the mixing treatment with the sludge, the stirring speed of the mixing treatment is 100rpm to 150rpm, and the stirring time is 5min to 10 min.
9. The sludge dewatering method according to any one of claims 1 to 7, wherein the dewatering treatment is pressure filtration at 4MPa to 5MPa for 10 to 20 min.
10. The method for dewatering sludge according to any one of claims 1-7, wherein the oxidizing agent is selected from at least one of peroxides, persulfates, permanganates.
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