CN118993392A - Landfill leachate coagulation coupling advanced oxidation pretreatment system and method - Google Patents
Landfill leachate coagulation coupling advanced oxidation pretreatment system and method Download PDFInfo
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- 238000005345 coagulation Methods 0.000 title claims abstract description 86
- 230000015271 coagulation Effects 0.000 title claims abstract description 86
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 86
- 230000003647 oxidation Effects 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 35
- 230000008878 coupling Effects 0.000 title claims description 28
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- 239000007800 oxidant agent Substances 0.000 claims abstract description 20
- 230000001590 oxidative effect Effects 0.000 claims abstract description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 77
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- 239000006228 supernatant Substances 0.000 claims description 42
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- 229910052742 iron Inorganic materials 0.000 claims description 32
- 238000002156 mixing Methods 0.000 claims description 30
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- 229910001448 ferrous ion Inorganic materials 0.000 claims description 7
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- 125000002091 cationic group Chemical group 0.000 claims description 5
- 229920002401 polyacrylamide Polymers 0.000 claims description 5
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 4
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- 230000007062 hydrolysis Effects 0.000 claims description 4
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- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 4
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims description 4
- 238000002203 pretreatment Methods 0.000 claims description 4
- 230000009467 reduction Effects 0.000 claims description 4
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- 239000003344 environmental pollutant Substances 0.000 abstract description 10
- 231100000719 pollutant Toxicity 0.000 abstract description 10
- 238000011065 in-situ storage Methods 0.000 abstract description 5
- -1 Fe(II) ions Chemical class 0.000 abstract description 2
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- 238000009303 advanced oxidation process reaction Methods 0.000 description 8
- 230000001112 coagulating effect Effects 0.000 description 8
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- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 description 4
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 4
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 4
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 4
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
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- 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
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- DGEZNRSVGBDHLK-UHFFFAOYSA-N [1,10]phenanthroline Chemical compound C1=CN=C2C3=NC=CC=C3C=CC2=C1 DGEZNRSVGBDHLK-UHFFFAOYSA-N 0.000 description 1
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- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
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- 239000002440 industrial waste Substances 0.000 description 1
- YPJCVYYCWSFGRM-UHFFFAOYSA-H iron(3+);tricarbonate Chemical compound [Fe+3].[Fe+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O YPJCVYYCWSFGRM-UHFFFAOYSA-H 0.000 description 1
- 239000000463 material Substances 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
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- 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
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/122—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using filter presses
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/70—Treatment of water, waste water, or sewage by reduction
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/06—Contaminated groundwater or leachate
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/06—Controlling or monitoring parameters in water treatment pH
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
本发明涉及一种垃圾渗滤液混凝耦合高级氧化预处理系统及方法，包括：与垃圾渗滤液源相连通的预酸化单元；酸性混凝反应单元，所述酸性混凝反应单元位于所述预酸化单元的下游；一级沉淀单元，所述一级沉淀单元位于所述酸性混凝反应单元的下游；高级氧化反应单元，所述高级氧化反应单元位于所述一级沉淀单元的下游；二级沉淀单元，所述二级沉淀单元位于所述高级氧化反应单元的下游；污泥处理单元，所述污泥处理单元位于所述二级沉淀单元的下游。通过对垃圾渗滤液初始pH值的预酸化调节，可在高效混凝去除污染物质的同时，酸性环境条件下可激发其原位产生大量Fe(Ⅱ)离子，仅需要投加氧化剂引发高级氧化反应，深度去除剩余难降解污染物，提高可生化性。
The present invention relates to a landfill leachate coagulation-coupled advanced oxidation pretreatment system and method, comprising: a pre-acidification unit connected to a landfill leachate source; an acidic coagulation reaction unit, the acidic coagulation reaction unit being located downstream of the pre-acidification unit; a primary precipitation unit, the primary precipitation unit being located downstream of the acidic coagulation reaction unit; an advanced oxidation reaction unit, the advanced oxidation reaction unit being located downstream of the primary precipitation unit; a secondary precipitation unit, the secondary precipitation unit being located downstream of the advanced oxidation reaction unit; and a sludge treatment unit, the sludge treatment unit being located downstream of the secondary precipitation unit. By pre-acidification adjustment of the initial pH value of the landfill leachate, while the pollutants can be removed by efficient coagulation, a large amount of Fe(II) ions can be stimulated to be generated in situ under acidic environmental conditions, and only an oxidant needs to be added to initiate an advanced oxidation reaction, so that the remaining difficult-to-degrade pollutants can be deeply removed and the biodegradability can be improved.
Description
Technical Field
The invention relates to the technical field of landfill leachate treatment, in particular to a landfill leachate coagulation coupling advanced oxidation pretreatment system and method.
Background
When household waste, industrial waste, or other types of waste are transported to a landfill and deposited, the waste undergoes a series of physical, chemical, and biological processes in which the liquid components of the waste interact with an external source of water such as rainwater to form a complex liquid mixture, namely landfill leachate. These landfill leachate often appear dark grey or black brown with malodor, have complex and variable chemical compositions, and are usually rich in organic, inorganic salts, heavy metals and other harmful substances. In particular, organic components thereof, such as volatile fatty acids, phenolic compounds and other refractory substances, pose a serious threat to the environment. These organic contaminants not only increase the Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) of the leachate, but may also cause damage to the surrounding ecosystem through groundwater penetration and surface water diffusion. In addition, landfill leachate becomes longer in storage time, and organic pollutants contained in landfill leachate gradually change to be difficult to degrade and low in biochemistry, so that the landfill leachate brings more challenges for subsequent treatment.
At present, various garbage landfills in China apply a plurality of process methods such as an evaporation method, a double-film method, a chemical oxidation method, a biological method and the like to solve the problem of garbage leachate treatment. The evaporation method and the double-membrane method respectively utilize the principles of liquid evaporation and semi-permeable membrane separation, and separate the landfill leachate into concentrated solution with higher pollutant concentration and clean produced water by physical principles, and the good effluent quality is common in emergency disposal of the landfill leachate, but the defects of the method and the double-membrane method are that besides higher investment and operation cost, the method and the device are most important, the actual removal of pollutants cannot be realized, and a large amount of concentrated solution which is more difficult to treat is generated. Chemical oxidation, while relatively good at degrading contaminants using various reaction mechanisms, is limited in its high cost of reagents and reduced contaminant removal in the practical handling of percolates. In comparison, most of the landfill sites in China are matched with biochemical equipment, and the microbial degradation of various pollutants is still the main method for treating the landfill leachate at present, but is limited by the increasing yield and pollution load of the landfill leachate and the increasing deterioration of biodegradability, and the current treatment requirements of individual biochemical units are difficult to meet. Therefore, how to develop a biochemical process pretreatment system capable of greatly reducing the organic load, improving the biodegradability and stabilizing the biochemical process with low cost is a problem which needs to be solved urgently at present.
Disclosure of Invention
The first object of the present invention is to address the technical problems existing in the prior art: the utility model provides a landfill leachate coagulates coupling advanced oxidation pretreatment systems, including pre-acidification unit, acid coagulation reaction unit, one-level precipitation unit, advanced oxidation reaction unit, second grade precipitation unit and sludge treatment unit, through the pre-acidification regulation to landfill leachate initial pH value, can be in high-efficient coagulating removal pollutant while, can arouse its normal position under the acidic environment condition and produce a large amount of Fe (II) ions, only need throw the oxidant and initiate advanced oxidation reaction, the degree of depth gets rid of remaining difficult degradation pollutant, reduce pollution load, improve the biodegradability of leachate after handling, thereby realize improving subsequent biochemical technological effect.
The second object of the invention is: provides a landfill leachate coagulation coupling advanced oxidation pretreatment method.
In order to achieve the above purpose, the invention adopts the following technical scheme:
A landfill leachate coagulation coupled advanced oxidation pretreatment system, the system comprising: the pre-acidification unit is communicated with a landfill leachate source and is used for mixing the landfill leachate with an acidulant so as to adjust the pH value to be weak acid; an acidic coagulation reaction unit downstream of the pre-acidification unit for mixing the landfill leachate from the pre-acidification unit with an iron-based coagulant to effect hydrolytic coagulation and reductive conversion; a first-stage precipitation unit, which is positioned at the downstream of the acidic coagulation reaction unit and is used for mixing landfill leachate from the acidic coagulation reaction unit with a coagulant aid so as to perform primary sedimentation separation; a higher oxidation reaction unit downstream of the primary precipitation unit for mixing the supernatant from the primary precipitation unit with an oxidant for higher oxidation; a secondary precipitation unit downstream of the advanced oxidation reaction unit for mixing the solution from the advanced oxidation reaction unit with a regulator and a coagulant aid, respectively, to perform secondary sedimentation separation; the sludge treatment unit is used for dehydrating the sludge from the upstream primary sedimentation unit and the upstream secondary sedimentation unit and conveying the filtrate to the pre-acidification unit.
Further, the pre-acidification unit comprises a first tank body, a first administration port and a second administration port are arranged at the top of the first tank body, and a first stirrer is axially arranged in the first tank body.
Further, the acidic coagulation reaction unit comprises a second tank body, a third administration port is arranged at the top of the second tank body, and a second stirrer is axially arranged in the second tank body.
Further, the first-stage sedimentation unit comprises a first reaction tank and a first sedimentation tank in sequence, a first liquid inlet for receiving landfill leachate is arranged on the side portion of the first reaction tank, a fourth drug administration port is arranged on the top of the first reaction tank, a third stirrer is axially arranged in the first reaction tank, a first liquid outlet for discharging the landfill leachate is arranged on the side portion of the first sedimentation tank, and a first sludge outlet for discharging sludge is arranged on the bottom of the first sedimentation tank.
Further, the advanced oxidation reaction unit comprises a third tank body, a second liquid inlet for receiving landfill leachate and a second liquid outlet for discharging the landfill leachate are arranged on the side portion of the third tank body, a fifth dosing port is arranged on the top portion of the third tank body, and a plurality of fourth stirrers are arranged in the third tank body side by side.
Further, the second-stage sedimentation unit comprises a second reaction tank and a second sedimentation tank in sequence, a third liquid inlet for receiving landfill leachate is arranged on the side part of the second reaction tank, a sixth chemical dosing port and a seventh chemical dosing port are arranged on the top of the second reaction tank, a fifth stirrer is axially arranged in the second reaction tank, a third liquid outlet for discharging pretreated landfill leachate is arranged on the side part of the second sedimentation tank, and a second sludge outlet for discharging sludge is arranged on the bottom of the second sedimentation tank.
Further, the sludge treatment unit is a plate-and-frame filter press.
Further, the iron-based coagulant is one or more of ferric chloride, ferric sulfate or polymeric ferric sulfate; the acidulant is sodium hydroxide and sulfuric acid; the oxidant is hydrogen peroxide or persulfate; the regulator is sodium hydroxide; the coagulant aid is cationic polyacrylamide.
According to the advanced oxidation pretreatment method for landfill leachate coagulation coupling, the method comprises the following steps:
Providing a landfill leachate source to a pre-acidification unit, adding an acidulant into the pre-acidification unit, and mixing and stirring the landfill leachate source and the acidulant to adjust the pH to be weak acidity; introducing the acidified landfill leachate into an acidic coagulation reaction unit, putting an iron-based coagulant into the acidic coagulation reaction unit, and mixing and stirring the acidified landfill leachate and the iron-based coagulant to generate hydrolysis coagulation and reduction conversion; introducing the coagulated landfill leachate into a primary sedimentation unit, adding a coagulant aid into the primary sedimentation unit, mixing and stirring the coagulated landfill leachate and the coagulant aid, performing primary sedimentation, and separating supernatant and sludge by gravity; introducing the supernatant into a high-grade oxidation reaction unit, adding an oxidant into the first-grade precipitation unit, mixing and stirring the supernatant and the oxidant, and carrying out high-grade oxidation; introducing the solution after advanced oxidation into a secondary precipitation unit, adding a regulator and a coagulant aid into the secondary precipitation unit, mixing the solution with the regulator and the coagulant aid, performing secondary sedimentation, and separating pretreated water and sludge by gravity; and introducing the sludge of the first-stage precipitation unit and the second-stage precipitation unit into a sludge treatment unit for dehydration, and refluxing the dehydrated filtrate into the pre-acidification unit.
Further, the supernatant in the primary precipitation unit contains ferrous ions, the pH in the pre-acidification unit is 4.5-5.5, and the pH in the secondary precipitation unit is 6-9.
The invention has the following advantages:
According to the landfill leachate coagulation coupling advanced oxidation pretreatment system, the Fe (II) ions which can be used for exciting advanced oxidation reaction are generated in situ in the acid coagulation reaction unit on the basis of synchronously promoting the iron coagulation effect through the initial pH value pre-acidification adjustment, so that no additional catalyst is required to be added, and the medicament cost is saved. The oxidant is added into the advanced oxidation reaction unit to form a coupling advanced oxidation reaction, so that the pollutants which cannot be removed by coagulation are subjected to oxidative degradation, secondary coagulation removal is realized, and the pollution removal effect of a single coagulation process is improved. Finally, the organic pollution load in the landfill leachate is greatly reduced, the removal effect is achieved by more than 80%, the B/C ratio is improved, the biodegradability is good, and the method has important significance for improving the subsequent biochemical treatment process.
Drawings
FIG. 1 is a schematic flow chart of a landfill leachate coagulation coupling advanced oxidation pretreatment system.
FIG. 2 is a graph showing the COD removal rate of the supernatant after coagulating the landfill leachate under the condition of different initial pH values in the embodiment 1 of the present invention.
FIG. 3 is a graph showing the Fe (II) ion yield of the supernatant fluid after coagulating the landfill leachate under the condition of different initial pH values in example 1 of the present invention.
Fig. 4 is a graph showing COD removal rate in the coupling advanced oxidation process under different hydrogen peroxide addition conditions in example 2 of the present invention.
FIG. 5 is a graph showing COD removal rate of the coupling advanced oxidation process under different sodium persulfate addition conditions in example 3 of the present invention.
Wherein 1 is a pre-acidification unit, 101 is a first tank, 102 is a first administration port, 103 is a second administration port, 104 is a first stirrer, 2 is an acidic coagulation reaction unit, 201 is a second tank, 202 is a third administration port, 203 is a second stirrer, 3 is a first-stage precipitation unit, 301 is a first reaction tank, 301a is a first liquid inlet, 301b is a fourth administration port, 301c is a third stirrer, 302 is a first precipitation tank, 302a is a first liquid outlet, 302b is a first mud outlet, 4 is an advanced oxidation reaction unit, 401 is a third tank, 402 is a second liquid inlet, 403 is a second liquid outlet, 404 is a fifth administration port, 405 is a fourth stirrer, 5 is a second precipitation unit, 501 is a second reaction tank, 501a is a third liquid inlet, 501b is a sixth administration port, 501c is a seventh administration port, 501d is a fifth stirrer, 502 is a second precipitation tank, 502a third mud outlet, 502b is a third mud outlet, and 502 is a mud outlet, 6 is a mud outlet.
Detailed Description
The following description is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood that when an element, component, and/or section is referred to as being "connected to" another element, component, and/or section, it can be directly connected to the other element, component, and/or section or intervening elements may be present. It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, components, and/or sections, these elements, components, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component or section from another element, component or section. Accordingly, a first element, component or section discussed below could be termed a second element, component or section without departing from the teachings of the present invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be appreciated that for clarity of illustration, the drawings herein are not drawn to scale and that the same or like reference numerals indicate the same or like parts or portions. Furthermore, it should be understood that any of the embodiments described herein and the technical features they include can be combined with one another.
The invention will be described in further detail with reference to the drawings and the detailed description.
As shown in fig. 1, a landfill leachate coagulation coupling advanced oxidation pretreatment system comprises a pre-acidification unit 1, an acidic coagulation reaction unit 2, a primary precipitation unit 3, an advanced oxidation reaction unit 4, a secondary precipitation unit 5 and a sludge treatment unit 6 which are arranged in series.
As shown in fig. 1, a pre-acidification unit 1 is in communication with a landfill leachate source, the pre-acidification unit 1 being used to mix the landfill leachate with an acidulant to adjust the pH to be weakly acidic. The pre-acidification unit 1 comprises a first tank body 101, wherein a first administration port 102 and a second administration port 103 are arranged at the top of the first tank body 101, a first stirrer 104 is axially arranged in the first tank body 101, and a pH on-line monitor is further arranged at the top of the first tank body 101 and used for monitoring the pH after acidification. The acidulant is sodium hydroxide and sulfuric acid, and the first administration port 102 is connected with an external sodium hydroxide adding device through a pipeline, and the second administration port 103 is connected with an external sulfuric acid adding device through a pipeline. The input line of the landfill leachate source is provided with a transfer pump.
As shown in fig. 1, an acidic coagulation reaction unit 2 is located downstream of the pre-acidification unit 1 for mixing the landfill leachate from the pre-acidification unit 1 with an iron-based coagulant for hydrolytic coagulation and reductive conversion. The acid coagulation reaction unit 2 comprises a second tank 201, a third administration port 202 is arranged at the top of the second tank 201, a second stirrer 203 is axially arranged in the second tank 201, and the second tank 201 is made of acid-resistant and corrosion-resistant materials. The iron-based coagulant is one or more of ferric chloride, ferric sulfate or polymeric ferric sulfate, and the third administration port 202 is connected with an external iron-based coagulant administration device through a pipeline. A transfer pump is arranged on the pipeline between the acidic coagulation reaction unit 2 and the pre-acidification unit 1.
As shown in fig. 1, a primary precipitation unit 3 is located downstream of the acid coagulation reaction unit 2 for mixing the landfill leachate from the acid coagulation reaction unit 2 with a coagulant aid for primary sedimentation separation. The primary sedimentation unit 3 comprises a first reaction tank 301 and a first sedimentation tank 302 in sequence, wherein a first liquid inlet 301a for receiving landfill leachate is arranged on the side part of the first reaction tank 301, a fourth chemical dosing port 301b is arranged on the top of the first reaction tank 301, a third stirrer 301c is axially arranged in the first reaction tank 301, a first liquid outlet 302a for discharging landfill leachate is arranged on the side part of the first sedimentation tank 302, a first sludge outlet for discharging sludge is arranged on the bottom of the first sedimentation tank 302, and the sludge discharged by the first sludge outlet is conveyed to the sludge treatment unit 6 in a pumping mode. The coagulant aid is cationic polyacrylamide, and the fourth administration port 301b is connected with an external coagulant aid administration device through a pipeline. A delivery pump is arranged on a pipeline between the primary precipitation unit 3 and the acidic coagulation reaction unit 2.
As shown in fig. 1, a higher oxidation reaction unit 4 is located downstream of the primary precipitation unit 3, for mixing the supernatant liquid from the primary precipitation unit 3 with an oxidizing agent to perform higher oxidation. The advanced oxidation reaction unit 4 comprises a third tank 401, a second liquid inlet 402 for receiving landfill leachate and a second liquid outlet 403 for discharging the landfill leachate are arranged on the side part of the third tank 401, a fifth dosing port 404 is arranged on the top of the third tank 401, the fifth dosing port 404 is located close to the second liquid inlet 402, rapid mixing of an oxidant and supernatant is guaranteed, oxidation efficiency is improved, and a plurality of fourth stirrers 405 are arranged side by side in the third tank 401. The oxidant is hydrogen peroxide or persulfate, and the fifth administration port 404 is connected with an external coagulant aid adding device through a pipeline.
As shown in fig. 1, a secondary precipitation unit 5 is located downstream of the advanced oxidation reaction unit 4 for mixing the solution from the advanced oxidation reaction unit 4 with a regulator and a coagulant aid, respectively, for secondary sedimentation separation. The secondary sedimentation unit 5 comprises a second reaction tank 501 and a second sedimentation tank 502 in sequence, wherein a third liquid inlet 501a for receiving landfill leachate is arranged at the side part of the second reaction tank 501, a sixth chemical dosing port 501b and a seventh chemical dosing port 501c are arranged at the top part of the second reaction tank 501, a fifth stirrer 501d is axially arranged in the second reaction tank 501, a third liquid outlet 502a for discharging pretreated landfill leachate is arranged at the side part of the second sedimentation tank 502, a second sludge outlet 502b for discharging sludge is arranged at the bottom part of the second sedimentation tank 502, and the sludge discharged by the second sludge outlet 502b is conveyed to the sludge treatment unit 6 in a pumping mode. Wherein, the top of the second reaction tank 501 is further configured with an online pH monitor for monitoring the adjusted pH. The regulator is sodium hydroxide, and the coagulant aid is cationic polyacrylamide.
As shown in fig. 1, a sludge treatment unit 6, the sludge treatment unit 6 is used for dewatering sludge from the upstream primary precipitation unit 3 and the secondary precipitation unit 5 and for transporting the filtrate to the pre-acidification unit 1. The sludge treatment unit 6 is a plate-and-frame filter press, the plate-and-frame filter press receives sludge and then carries out mechanical dehydration, the filter-pressed sludge is recycled, and the generated filtrate is pumped into the pre-acidification unit 1 for treatment.
The action mechanism of the landfill leachate coagulation coupling advanced oxidation pretreatment system is as follows: the method is characterized in that anions such as carbonic acid/bicarbonate radical and the like in a water body are removed by adjusting the initial pH value of landfill leachate to reach a weak acidic condition of 4.5-5.5 in a pre-acidification unit 1, so that insoluble solid impurities such as ferric carbonate and the like generated by an iron-based coagulant are prevented from being influenced, the coagulation effect is reduced, and meanwhile, the acidic condition is favorable for the coagulation removal effect of humus organic matters. Adding an iron-based coagulant into the acidic coagulation reaction unit 2, wherein the iron-based coagulant is a coagulant mainly containing ferric iron such as ferric chloride, ferric sulfate or polymeric ferric sulfate, and the pH value is further reduced to about 3, and at the moment, ferric iron ions in the iron-based coagulant undergo two processes of hydrolysis coagulation and reduction conversion: part of ferric ions are hydrolyzed to form iron flocs, and electric double layer compression, adsorption electric neutralization, adsorption bridging, sediment net capturing and the like are carried out, so that organic matters are removed by precipitation; the other part of ferric ions are kept in an ionic state in an acidic environment, and are excited by an organic matter with reducing capability to be reduced in situ to ferrous ions, and the ferrous ions are dissolved in the coagulating supernatant, wherein the landfill leachate is subjected to anaerobic landfill for a period of time, and the landfill leachate is converted in property and is distinguished from an aerobic oxidation state and enters a reducing state, so that the reducing capability is obtained. The sludge-water separation is carried out by the first-stage precipitation unit 3, the supernatant fluid after the sludge-water separation is introduced into the advanced oxidation reaction unit 4, and oxidant (hydrogen peroxide, persulfate and the like) is added, under the catalysis of ferrous ions, fenton or Fenton-like advanced oxidation reaction is carried out, a large number of free radicals (OH, SO 4 - and the like) with strong oxidizing property are generated, and the pollutants which are difficult to degrade and biochemically remove are deeply oxidized and decomposed into CO 2、H2 O and small molecular organic matters. And finally, the pH value is adjusted back to be neutral through a secondary precipitation unit 5 to form new iron flocs, so that the secondary coagulation removal of residual organic matters which cannot be removed by coagulation originally is realized, and the pretreated landfill leachate is obtained.
According to the landfill leachate coagulation coupling advanced oxidation pretreatment method, the method comprises the following steps of:
Providing a landfill leachate source to a pre-acidification unit 1, adding an acidulant into the pre-acidification unit 1, and mixing and stirring the landfill leachate source and the acidulant to adjust the pH to be weak acid; specifically, the landfill leachate to be treated enters the first tank 101, sodium hydroxide and sulfuric acid are added into the landfill leachate through a dosing device, and the mixture is stirred uniformly and the pH is regulated to be within the weak acidity range of 4.5-5.5.
Introducing the acidified landfill leachate into an acidic coagulation reaction unit 2, putting an iron-based coagulant into the acidic coagulation reaction unit 2, mixing and stirring the acidified landfill leachate and the iron-based coagulant to generate hydrolysis coagulation and reduction conversion; specifically, the acidified landfill leachate enters the second tank 201, and a certain amount of iron-based coagulant is added into the landfill leachate through a dosing device, so that the landfill leachate is fully and uniformly stirred to perform a coagulation reaction.
Introducing the coagulated landfill leachate into a first-stage precipitation unit 3, adding a coagulant aid into the first-stage precipitation unit 3, mixing and stirring the coagulated landfill leachate and the coagulant aid, performing primary sedimentation, and separating supernatant and sludge by gravity; specifically, the solution to be coagulated uniformly enters a first reaction tank 301, coagulant aid is added into the coagulating solution through a dosing device, sludge particles become large after full stirring, then the sludge enters a first sedimentation tank 302, gravity sludge is naturally precipitated to the bottom of the first sedimentation tank, and supernatant overflows and is discharged;
Introducing the supernatant into a advanced oxidation reaction unit 4, putting an oxidant into a primary precipitation unit 3, mixing and stirring the supernatant and the oxidant, and performing advanced oxidation; specifically, the supernatant enters the third tank 401, the oxidant is added into the supernatant through the dosing device, and the mixture is fully mixed for reaction through multistage stirring.
Introducing the solution after advanced oxidation into a secondary precipitation unit 5, adding a regulator and a coagulant aid into the secondary precipitation unit 5, mixing the solution with the regulator and the coagulant aid, performing secondary sedimentation, and separating pretreated water and sludge by gravity; specifically, the solution after advanced oxidation reaction enters a second reaction tank 501, a regulator is added into the solution through a dosing device to regulate the pH value to be within a range of 6-9, a large amount of iron flocs are formed, a coagulant aid is added into the solution, the iron flocs are fully stirred and then are agglomerated, the mixture enters a second sedimentation tank 502, gravity sludge is naturally precipitated to the bottom of the mixture, and supernatant fluid is produced water through a pretreatment system and overflowed and discharged.
The sludge of the primary sedimentation unit 3 and the secondary sedimentation unit 5 is introduced into the sludge treatment unit 6 to be dehydrated, and the dehydrated filtrate is returned to the pre-acidification unit 1. Specifically, when the sludge precipitated at the bottoms of the first sedimentation tank 302 and the second sedimentation tank 502 reaches a certain amount, the sludge is pumped into a plate filter press by a sludge pump, the plate filter press is utilized for mechanical dehydration, the obtained filtrate flows back into the first tank 101, and the dehydrated sludge is utilized for subsequent recycling.
Wherein the supernatant in the primary precipitation unit 3 contains ferrous ions, the pH in the pre-acidification unit 1 is 4.5-5.5, and the pH in the secondary precipitation unit 5 is 6-9.
After the garbage percolate is initially regulated to a proper weak acidic pH value, an iron-based coagulant is added for acidic coagulation, a large amount of Fe (II) ions can be generated in situ by coagulating the supernatant while deodorizing and decoloring and removing most of humus organic matters, a certain amount of oxidant can be directly added under the condition of not regulating the pH value so as to further realize Fenton/Fenton-like and other advanced oxidation reactions, residual organic pollutants which cannot be flocculated, are difficult to degrade and have poor biochemistry are deeply removed from the supernatant, a materialization pretreatment process of coagulating and coupling advanced oxidation is realized, and the problems of high organic load, low biochemistry and poor biochemical effect of raw liquid in the existing biochemical treatment process of the garbage landfill are solved.
Example 1
Fig. 2 and 3 show the effect of the removal rate of COD from the supernatant and the generation of Fe (ii) ions after coagulation of the landfill leachate at different initial pH values, respectively.
The garbage leachate to be treated enters a pre-acidification unit 1, the initial pH value is regulated and controlled by controlling the adding amount of sodium hydroxide and sulfuric acid according to a pH online monitor, the pH values are respectively 7.5, 7.0, 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, 3.5 and 3.0, the garbage leachate with the initial value adjusted enters an acidic coagulation reaction unit 2, commercial polymeric ferric sulfate (the total iron mass fraction is 11.8%) with the volume ratio of 1% is added, the mixed solution after full stirring enters a first-stage precipitation unit 3, a cationic polyacrylamide coagulant aid is added into a first reaction tank 301, so that the coagulated sludge particles are enlarged and then enter a first precipitation tank 302 for precipitation, and the coagulating supernatant is obtained after mud-water separation. The coagulation supernatant was tested for COD value and Fe (II) ion concentration.
Wherein, the COD value test method is according to the dichromate method GB 11914-89; the Fe (II) ion concentration test method is based on the phenanthroline spectrophotometry HJ/T345-2007.
As shown in figure 2, under the condition of different initial pH values, the COD in the landfill leachate can be removed by adding the polymeric ferric sulfate with the volume ratio of 1%, and particularly, a good removal effect is achieved within the pH range of 4.5-5.5, and the removal rate is more than 65%. In the range of higher or lower pH value, the removal effect of COD is not ideal.
As shown in FIG. 3, by detecting the concentration of Fe (II) ions in the supernatant, ferrous ions can be detected in the supernatant, which means that ferric iron (derived from polymeric ferric sulfate) dissolved in the landfill leachate can be effectively converted into a divalent state through the coagulation process, and a higher yield of Fe (II) ions can be obtained under the condition that the initial pH value is 4.5-5.5, and the yield is more than 850 mg/L.
Example 2
Fig. 4 shows the effect of removal of COD by adding different ratios of hydrogen peroxide to landfill leachate advanced oxidation depth based on the supernatant of the first sedimentation tank 302 in example 1.
The initial value is pH=5, the adding amount of the coagulant polymeric ferric sulfate is 1% by volume, the supernatant produced in the first sedimentation tank 302 enters the advanced oxidation reaction unit 4, the commercial concentration of 30% hydrogen peroxide is directly added, the adding proportion is that the molar ratio of Fe (II) ions produced according to the supernatant is 1:0, 1:1, 1:2, 1:3, 1:4 and 1:5 respectively, and after full stirring reaction, the COD can be tested to obtain the mineralization rate of the organic matters. Then the solution enters a secondary sedimentation unit 5, the pH value range is regulated within 6-9 in a second reaction tank 501 to form a large amount of iron flocs, coagulant aid is added into the solution, the iron flocs are held after full stirring, the solution enters a second sedimentation tank 502, gravity sludge is naturally sedimented to the bottom of the second sedimentation tank, and the COD value of supernatant fluid is tested to obtain the COD total removal rate in the advanced oxidation process.
Wherein, the COD value test method is based on the dichromate method GB 11914-89.
As shown in FIG. 4, in the absence of added hydrogen peroxide, advanced oxidation reaction cannot occur, and mineralization and total removal are not obvious. After hydrogen peroxide is added, fenton advanced oxidation reaction can be carried out under the condition that Fe (II) exists, organic matters are further mineralized and removed, and the mineralization rate of the organic matters is gradually increased along with the increase of the adding amount of the hydrogen peroxide. After the reaction is completed, secondary iron flocs are formed by pH adjustment, and organic matters are further removed, so that the advanced oxidation process can be proved to partially change the organic matters, and the organic matters are removed through the coagulation process. In general, the Fenton advanced oxidation process formed by adding hydrogen peroxide can deeply remove the coagulation supernatant, the total removal rate is up to more than 25%, and the highest removal rate can be up to 40%. Through advanced oxidation and pH callback coagulation, the B/C ratio of landfill leachate is improved to more than 2.5 from original 0.05, the biodegradability is remarkably improved, and the method is beneficial to subsequent biochemical treatment.
Example 3
Fig. 5 shows the effect of adding different ratios of hydrogen peroxide on the advanced oxidation depth removal COD of landfill leachate based on the supernatant of the first sedimentation tank 302 in example 1.
The initial value is pH=5, the adding amount of the coagulant polymeric ferric sulfate is 1% by volume, the supernatant produced in the first sedimentation tank 302 enters the advanced oxidation reaction unit 4, the commercial sodium persulfate solution with the concentration of 1M is directly added, the adding proportion is that the molar ratio of Fe (II) ions produced according to the supernatant is 1:0, 1:1, 1:2, 1:3, 1:4 and 1:5 respectively, and after full stirring reaction, the COD can be tested to obtain the mineralization rate of the organic matters. Then the solution enters a secondary sedimentation unit 5, the pH value range is regulated within 6-9 in a second reaction tank 501 to form a large amount of iron flocs, coagulant aid is added into the solution, the iron flocs are held after full stirring, the solution enters a second sedimentation tank 502, gravity sludge is naturally sedimented to the bottom of the second sedimentation tank, and the COD value of supernatant fluid is tested to obtain the COD total removal rate in the advanced oxidation process.
Wherein, the COD value test method is based on the dichromate method GB 11914-89.
As shown in FIG. 5, in the absence of added hydrogen peroxide, advanced oxidation reaction cannot occur, and mineralization and total removal are not obvious. When sodium persulfate is added, fenton-like advanced oxidation reaction can be carried out under the condition that Fe (II) exists, organic matters are further mineralized and removed, and the mineralization rate of the organic matters is gradually increased along with the increase of the adding amount of the sodium persulfate. After the reaction is completed, secondary iron flocs are formed by pH adjustment, and organic matters are further removed, so that the advanced oxidation process can be proved to partially change the organic matters, and the organic matters are removed through the coagulation process. In general, the Fenton advanced oxidation process formed by adding hydrogen peroxide can deeply remove the coagulation supernatant, the total removal rate is up to more than 12%, and the highest removal rate can be up to 30%. Through advanced oxidation and pH callback coagulation, the B/C ratio of landfill leachate is improved to more than 2.0 from original 0.05, the biodegradability is remarkably improved, and the method is beneficial to subsequent biochemical treatment.
Comparative example 1
For comparison with the traditional advanced oxidation pretreatment, the initial value of the landfill leachate is adjusted to be 3 through pH, and ferrous sulfate and hydrogen peroxide are directly added into an advanced oxidation reaction unit 4, wherein the concentration of Fe (II) ions in a ferrous sulfate solution is 850mg/L, and the adding amount of the hydrogen peroxide is the molar ratio Fe (II): hydrogen peroxide = 1: and 4, after the reaction is fully stirred, the mixture enters a reaction zone of a sedimentation tank to adjust the pH value to 6-9, and after the mixture is fully and uniformly stirred, the mixture enters a second sedimentation tank 502 to be sedimented, and the COD value of the supernatant is tested to obtain the COD removal rate.
Wherein, the COD value test method is based on the dichromate method GB 11914-89.
Tests show that the total removal rate of the COD of the landfill leachate by the traditional Fenton advanced oxidation is only 10%, which is far lower than that of the coagulation coupling advanced oxidation pretreatment system of the invention, and meanwhile, the cost is slightly higher than that of the coagulation coupling advanced oxidation pretreatment system of the invention, and the B/C ratio is not obviously improved.
In general, the landfill leachate coagulation coupling advanced oxidation pretreatment system provided by the invention has the advantages that the Fe (II) ions which can be used for exciting advanced oxidation reaction are generated in situ in the acid coagulation reaction unit on the basis of synchronously promoting the iron coagulation effect through the pre-acidification adjustment of the initial pH value, no additional catalyst is needed, and the medicament cost is saved. The oxidant is added into the advanced oxidation reaction unit to form a coupling advanced oxidation reaction, so that the pollutants which cannot be removed by coagulation are subjected to oxidative degradation, secondary coagulation removal is realized, and the pollution removal effect of a single coagulation process is improved. Finally, the organic pollution load in the landfill leachate is greatly reduced, the removal effect is achieved by more than 80%, the B/C ratio is improved, the biodegradability is good, and the method has important significance for improving the subsequent biochemical treatment process.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.
Claims (10)
1. A landfill leachate coagulation coupling advanced oxidation pretreatment system, the system comprising: the pre-acidification unit is communicated with a landfill leachate source and is used for mixing the landfill leachate with an acidulant so as to adjust the pH value to be weak acid;
an acidic coagulation reaction unit downstream of the pre-acidification unit for mixing the landfill leachate from the pre-acidification unit with an iron-based coagulant to effect hydrolytic coagulation and reductive conversion;
The first-stage precipitation unit is positioned at the downstream of the acidic coagulation reaction unit and is used for mixing landfill leachate from the acidic coagulation reaction unit with a coagulant aid so as to perform primary sedimentation separation; a higher oxidation reaction unit downstream of the primary precipitation unit for mixing the supernatant from the primary precipitation unit with an oxidant for higher oxidation;
A secondary precipitation unit downstream of the advanced oxidation reaction unit for mixing the solution from the advanced oxidation reaction unit with a regulator and a coagulant aid, respectively, to perform secondary sedimentation separation;
And the sludge treatment unit is used for dehydrating the sludge from the upstream primary sedimentation unit and the upstream secondary sedimentation unit and conveying filtrate to the pre-acidification unit.
2. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the pre-acidification unit comprises a first tank body, a first administration port and a second administration port are arranged at the top of the first tank body, and a first stirrer is axially arranged in the first tank body.
3. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the acid coagulation reaction unit comprises a second tank body, a third administration port is arranged at the top of the second tank body, and a second stirrer is axially arranged inside the second tank body.
4. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the primary sedimentation unit comprises a first reaction tank and a first sedimentation tank in sequence, a first liquid inlet for receiving landfill leachate is arranged on the side portion of the first reaction tank, a fourth administration port is arranged on the top portion of the first reaction tank, a third stirrer is axially arranged in the first reaction tank, a first liquid outlet for discharging landfill leachate is arranged on the side portion of the first sedimentation tank, and a first sludge outlet for discharging sludge is arranged on the bottom portion of the first sedimentation tank.
5. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the advanced oxidation reaction unit comprises a third tank body, a second liquid inlet for receiving landfill leachate and a second liquid outlet for discharging landfill leachate are arranged on the side portion of the third tank body, a fifth administration port is arranged on the top portion of the third tank body, and a plurality of fourth stirrers are arranged in the third tank body side by side.
6. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the secondary sedimentation unit comprises a second reaction tank and a second sedimentation tank in sequence, a third liquid inlet for receiving landfill leachate is arranged on the side part of the second reaction tank, a sixth dosing port and a seventh dosing port are arranged on the top part of the second reaction tank, a fifth stirrer is axially arranged in the second reaction tank, a third liquid outlet for discharging the pretreated landfill leachate is arranged on the side part of the second sedimentation tank, and a second sludge outlet for discharging sludge is arranged on the bottom part of the second sedimentation tank.
7. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the sludge treatment unit is a plate-and-frame filter press.
8. The landfill leachate coagulation coupling advanced oxidation pretreatment system according to claim 1, wherein the iron-based coagulant is one or more of ferric chloride, ferric sulfate or polymeric ferric sulfate; the acidulant is sodium hydroxide and sulfuric acid; the oxidant is hydrogen peroxide or persulfate; the regulator is sodium hydroxide; the coagulant aid is cationic polyacrylamide.
9. A method of using a landfill leachate coagulation coupled advanced oxidation pretreatment system according to any of the preceding claims, comprising the steps of:
Providing a landfill leachate source to a pre-acidification unit, adding an acidulant into the pre-acidification unit, and mixing and stirring the landfill leachate source and the acidulant to adjust the pH to be weak acidity;
introducing the acidified landfill leachate into an acidic coagulation reaction unit, putting an iron-based coagulant into the acidic coagulation reaction unit, and mixing and stirring the acidified landfill leachate and the iron-based coagulant to generate hydrolysis coagulation and reduction conversion;
introducing the coagulated landfill leachate into a primary sedimentation unit, adding a coagulant aid into the primary sedimentation unit, mixing and stirring the coagulated landfill leachate and the coagulant aid, performing primary sedimentation, and separating supernatant and sludge by gravity;
introducing the supernatant into a high-grade oxidation reaction unit, adding an oxidant into the first-grade precipitation unit, mixing and stirring the supernatant and the oxidant, and carrying out high-grade oxidation;
Introducing the solution after advanced oxidation into a secondary precipitation unit, adding a regulator and a coagulant aid into the secondary precipitation unit, mixing the solution with the regulator and the coagulant aid, performing secondary sedimentation, and separating pretreated water and sludge by gravity;
and introducing the sludge of the first-stage precipitation unit and the second-stage precipitation unit into a sludge treatment unit for dehydration, and refluxing the dehydrated filtrate into the pre-acidification unit.
10. The landfill leachate coagulation coupling advanced oxidation pretreatment method according to claim 9, wherein supernatant fluid in the primary precipitation unit contains ferrous ions, the pH in the pre-acidification unit is 4.5-5.5, and the pH in the secondary precipitation unit is 6-9.
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