An Enhanced Treatment Method for Rainy Season Overflow Wastewater Based on Transition Metal Modified Microsand

Abstract

This invention belongs to the field of rapid overflow sewage treatment technology, and relates to a method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand. The method includes: adding rainy season overflow sewage and coagulant to a coagulation tank for mixing and stirring to obtain water body I; transferring water body I to a dosing tank, adding a coagulant aid and stirring, then adding a metal-based supported catalytic-loading medium material and mixing and stirring to obtain water body II; transferring water body II to a flocculation tank for slow stirring, adding an oxidant and stirring to obtain water body III; transferring water body III to a sedimentation tank for sedimentation treatment to obtain supernatant and precipitated sludge containing the metal-based supported catalytic-loading medium material; and recovering the obtained precipitated sludge through magnetic separation and reusing it in the dosing tank for reuse. The catalytic-loading medium of this invention can remove particulate pollutants from overflow sewage in a short time, while also removing dissolved organic matter and ammonia nitrogen, and has the advantages of being economical and efficient.

Description

Technical Field

[0001] This invention relates to the field of rapid treatment technology for overflow sewage during the rainy season, and in particular to an enhanced treatment method for overflow sewage during the rainy season based on transition metal modified microsand. Background Technology

[0002] Due to intensifying global climate change, extreme weather events, particularly torrential rains, are increasing in intensity and frequency worldwide. When the flow rate into combined sewer systems exceeds the maximum capacity of the drainage pipes, untreated mixed sewage, industrial wastewater, and rainwater are discharged into surface water bodies through overflow wells or pumping stations, causing black and smelly water bodies during rainy days. Separate sewer systems can solve this problem, but sewage and rainwater pipes in these systems are often not completely separated. Due to the mixing of sewage and rainwater, sewage containing large amounts of pollutants is mixed with rainwater and discharged into receiving water bodies without treatment. This phenomenon not only affects water quality but can also cause urban flooding, threatening residents' lives and urban safety. Therefore, developing rapid and efficient measures for treating rainwater overflows is of great significance to the ecological environment and human health.

[0003] Given the suddenness and high pollution load of sewage overflows during rainy days, the measures taken should allow for the rapid passage of large volumes of overflowing sewage while also achieving good treatment results. Loaded flocculation is a highly efficient coagulation and sedimentation process based on physicochemical processes. It involves adding a high-density loading medium to a chemically unstable colloidal particle suspension. Under the action of polymers, the loading medium combines with the micro-flocculations to form large-sized, dense loaded flocs with good settling properties, achieving sedimentation in a short time. Quartz sand, with its high density and hardness, is often chosen as a loading medium for loaded flocculation; however, its density and adsorption capacity are limited, hindering the potential for further improvements in treatment efficiency and effectiveness in water treatment. Magnetic particles have also been used as loading media, but their high addition cost and power consumption limit their practical application in water treatment.

[0004] Flocculation primarily removes particulate pollutants from water, but its effectiveness in removing dissolved pollutants is relatively poor. Chemical oxidation, on the other hand, can rapidly and efficiently remove dissolved pollutants from water through oxidation. Therefore, a synergistic coagulation-oxidation approach is employed to remove multi-source, multi-type, and multi-state pollutants from overflow wastewater. Studies have shown that metal-based catalysts such as iron, copper, and nickel can activate oxidants to generate highly reactive species, thereby rapidly oxidizing and degrading pollutants.

[0005] Based on this, we consider loading mono / bimetallic catalytic materials onto quartz sand to treat dissolved pollutants in overflow wastewater that are difficult to remove during the coagulation process using catalytic oxidants (sodium hypochlorite, potassium ferrate, etc.), thereby improving oxidation reaction efficiency, enhancing oxidation capacity, and improving treatment effect. This allows for the rapid treatment of overflow wastewater while simultaneously removing dissolved organic matter and ammonia nitrogen. Summary of the Invention

[0006] To address the technical problems of existing overflow sewage treatment methods, such as the large land area required, long time consumption, and poor removal effect of dissolved organic matter, the present invention provides an enhanced treatment method for overflow sewage during the rainy season based on transition metal modified microsand.

[0007] The purpose of this invention is to provide a method for enhanced treatment of rainwater overflow wastewater based on transition metal modified microsand, comprising the following steps:

[0008] The overflow sewage during the rainy season and the coagulant were added to the coagulation tank and mixed to obtain water body I;

[0009] Water body I is transported to a dosing tank, coagulant is added and stirred, then metal-based supported catalyst-loading medium material is added, and the mixture is stirred to obtain water body II;

[0010] Water body II is transported to a flocculation tank and slowly stirred. An oxidant is added and stirred to obtain water body III.

[0011] The water body III is transported to a sedimentation tank for sedimentation treatment to obtain supernatant water and precipitated sludge containing metal-based supported catalyst-loading medium material; the obtained precipitated sludge is recovered by magnetic separation and reused in the addition tank to achieve reuse;

[0012] In some embodiments of the present invention, the metal-based supported catalyst-loading medium material is prepared by the following method:

[0013] S1: Soak the quartz sand in an acid solution, clean and dry it for later use;

[0014] S2: Add quartz sand to the metal salt solution, sonicate, then stir for the first time for 5-6 hours, adjust the solution to alkaline, and continue stirring for the second time to obtain the reaction mixture;

[0015] S3: The resulting reaction mixture is aged, then solid-liquid separation is performed and the solid phase is taken. The obtained solid phase is calcined to obtain a metal-based supported catalyst-loading medium material.

[0016] In some embodiments of the present invention, the coagulant is selected from one or more of aluminum sulfate, ferric chloride, polyferric sulfate, and polyaluminum chloride;

[0017] The dosage of the coagulant is 2.5-5.5 mg / L;

[0018] The coagulant is selected from polyacrylamide and / or starch-based polymers, wherein the polyacrylamide is anionic polyacrylamide, cationic polyacrylamide, or nonionic polyacrylamide, and the weight-average molecular weight is 14,000,000-16,000,000 Da.

[0019] The dosage of the coagulant is 0.5-1.2 mg / L.

[0020] In some embodiments of the present invention, the dosage of the metal-based supported catalyst-loading medium material is 3-5 g / L.

[0021] In some embodiments of the present invention, in step S1, the acid in the acid solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and oxalic acid;

[0022] The concentration of the acid solution is 5-10 wt%;

[0023] Soaking time is 12-24 hours.

[0024] In some embodiments of the present invention, in step S2, the metal in the metal salt is selected from one or more of iron, copper, and nickel;

[0025] The salt in the metal salt is selected from one or more of nitrates, sulfates and chlorides;

[0026] The concentration of the metal salt solution is 0.1-0.5M.

[0027] In some embodiments of the present invention, in step S2, the frequency of ultrasound is 40-50Hz, the ultrasound time is 20-30min, and the temperature is 25-35℃.

[0028] The first stirring time is 5-6 hours, and the temperature is 50-60℃;

[0029] The second stirring time is 20-30 minutes, and the temperature is 50-60℃.

[0030] In some embodiments of the present invention, in step S3, the aging temperature is 50-65°C and the aging time is 12-24 hours.

[0031] In some embodiments of the present invention, in step S3, the calcination temperature is 400-600°C and the calcination time is 2-5 hours.

[0032] In some embodiments of the present invention, the oxidant includes potassium ferrate and sodium hypochlorite, wherein the molar concentration ratio of potassium ferrate and sodium hypochlorite is (0.05-0.07):(0.5-0.7).

[0033] The technical solution of the present invention has the following advantages compared with the prior art:

[0034] (1) The method provided by the present invention uses quartz sand loaded with catalyst as the catalyst-loading medium. The quartz sand used is naturally formed quartz ore, which has a large output and low price. In addition, the synthesized transition metal modified micro sand is magnetic and can be magnetically recycled. The price is lower than that of magnetic types on the market.

[0035] (2) The transition metal modified microsand used in the method provided by this invention exhibits a dual synergistic mechanism in overflow sewage treatment. As a highly efficient flocculation core, it significantly increases the collision frequency between particles, promotes floc formation and rapid growth, and gets rid of the dependence of traditional coagulation and sedimentation on long retention time. It completes the reaction and clarification within 5 minutes, meeting the characteristics of overflow sewage with fast inflow and large fluctuations in water quality and quantity, requiring rapid treatment. The loaded transition metal, with its variable valence state, accelerates the decomposition of oxidants and electron transfer, and efficiently generates highly active species such as hydroxyl radicals and atomic oxygen. In the micro-interface area of ​​the loaded floc, through the synergistic effect of "adsorption-catalysis-oxidation", it achieves in-situ degradation of dissolved pollutants (organic matter and ammonia nitrogen), and can realize the synergistic treatment of multiple types of pollutants in overflow sewage.

[0036] (3) The method provided by this invention uses coagulation followed by oxidation. The metal-based supported catalyst-loading medium material continues to exert its catalytic effect after being encapsulated by flocs. The loose and porous structure of the flocs ensures the free diffusion of oxidants (such as sodium hypochlorite and potassium ferrate) and dissolved pollutants. At the same time, the flocs can adsorb and enrich organic matter in the water, forming a local high-concentration microenvironment around the microsand, which is conducive to the oxidation and mineralization of organic matter. Compared with oxidation followed by coagulation, it has a better removal effect on dissolved organic matter. Attached Figure Description

[0037] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0038] Figure 1 This is a process flow diagram of the catalytic-loading medium enhanced treatment of overflow wastewater in an embodiment of the present invention;

[0039] Figure 2 This invention relates to the molecular weight distribution of organic matter in overflow wastewater after coagulation-oxidation treatment using different metal-based supported catalyst-loading media materials in this embodiment of the invention. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0041] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0042] In this invention, "M" represents mol / L and "mM" represents mmol / L.

[0043] As mentioned above, a first aspect of the present invention provides a method for enhanced treatment of rainy season overflow wastewater based on transition metal modified microsand, the method comprising the following steps:

[0044] The overflow sewage during the rainy season and the coagulant were added to the coagulation tank and mixed to obtain water body I;

[0045] Water body I is transported to a dosing tank, coagulant is added and stirred, then metal-based supported catalyst-loading medium material is added, and the mixture is stirred to obtain water body II;

[0046] Water body II is transported to a flocculation tank and slowly stirred. An oxidant is added and stirred to obtain water body III.

[0047] The water body III is transported to a sedimentation tank for sedimentation treatment to obtain supernatant water and precipitated sludge containing metal-based supported catalyst-loaded media material; the obtained precipitated sludge is then recovered through magnetic separation and reused in a flocculation tank for repeated use.

[0048] The metal-based supported catalyst-loading medium material is obtained by a method including the following steps:

[0049] S1: Soak the quartz sand in an acid solution, clean and dry it for later use;

[0050] S2: Add quartz sand to the metal salt solution, sonicate, then stir for the first time for 5-6 hours, adjust the solution to alkaline, and continue stirring for the second time to obtain the reaction mixture;

[0051] S3: The resulting reaction mixture is aged, then solid-liquid separation is performed and the solid phase is taken. The obtained solid phase is calcined to obtain a metal-based supported catalyst-loading medium material.

[0052] The specific preparation method is as follows:

[0053] S1: Soak 100g of quartz sand in 500mL of 10% hydrochloric acid for 12-24h, then rinse it with ultrapure water until the pH of the rinsing water is close to neutral. Then dry the quartz sand in an oven at 100-105℃ for 3h and store it for later use.

[0054] S2: Dissolve the metal salt in ultrapure water to prepare a 0.1M metal salt solution, add quartz sand, stir at 50℃ for 6 hours, add alkaline solution dropwise to adjust the pH of the solution to alkaline (at this time, the temperature needs to be kept constant), and stir for 20-30 minutes.

[0055] S3: After aging in a water bath at 65℃ for 6-12 hours, solid-liquid separation is performed, and the solid phase is then dried and ground sequentially.

[0056] S4: The dried material was calcined in a muffle furnace at 450°C for 3 hours to obtain the catalyst-loading medium material.

[0057] In this invention, the metal-based supported catalytic-loading medium material is an important component for treating overflow sewage. It can not only catalyze oxidants, but also act as a loading medium during coagulation, increasing floc particle size and settling velocity. It can remove dissolved organic matter and ammonia nitrogen from overflow sewage in a short time (within 1 minute) through coagulation and oxidation.

[0058] Preferably, in step S1, the solid-liquid ratio of the quartz sand to hydrochloric acid is (1:3)-(1:6) (mass-volume ratio, g / mL), that is, 100g of quartz sand is placed in 500mL of 10wt% hydrochloric acid.

[0059] More preferably, in step S1, the average particle diameter of the quartz sand is 74-120 μm.

[0060] More preferably, in step S1, the drying process is carried out in an oven, and the drying conditions are: temperature 100-105℃ and time 3-5h.

[0061] Preferably, in step S2, the metal salt in the metal salt solution is selected from one or more of ferric nitrate nonahydrate, copper nitrate trihydrate, and nickel nitrate hexahydrate;

[0062] More preferably, in step S2, the metal salt solution is a 0.1M copper nitrate solution, a 0.1M nickel nitrate solution, a 0.1M ferric nitrate solution, a 0.1M mixed solution of copper nitrate and nickel nitrate, a 0.1M mixed solution of copper nitrate and ferric nitrate, and a 0.1M mixed solution of nickel nitrate and ferric nitrate. The mixed solution refers to a total metal ion concentration of 0.1M and a single metal ion concentration of 0.05M.

[0063] In a preferred embodiment, in step S2, the temperature of the metal salt solution is controlled to be around 50-60°C.

[0064] More preferably, in step S2, the alkaline adjusting agent solution for adjusting the solution to alkalinity is a 1-2M sodium hydroxide solution and / or 10-25% ammonia solution.

[0065] Preferably, in step S3, solid-liquid separation is performed by vacuum filtration, and the filter membrane is a 0.45 μm polyethersulfone filter membrane.

[0066] More preferably, step S3 further includes drying the obtained solid phase in an oven, wherein the drying process is carried out at a temperature of 100-105°C for 5-6 hours.

[0067] Preferably, in step S3, the dried material is placed in a crucible for calcination at a temperature of 400-600°C for 2-5 hours, with a heating rate of 5-10°C per minute.

[0068] The present invention does not have any particular requirements regarding the grinding method; exemplarily, the grinding process is performed using a mortar and pestle. Further details of the present invention will not be elaborated upon here, and those skilled in the art should not construe this as a limitation of the invention.

[0069] Preferably, the coagulant is aluminum sulfate octadechydrate.

[0070] More preferably, the dosage of aluminum sulfate is 2.5-5.5 mg / L (calculated as aluminum).

[0071] Preferably, the mixing conditions for the overflow sewage and coagulant during the rainy season are: a stirring speed of 300-600 s. -1 The time is 1-2 minutes.

[0072] Preferably, the coagulant is selected from anionic polyacrylamide with a weight-average molecular weight of 14,000,000-16,000,000 Da.

[0073] Preferably, the dosage of polyacrylamide is 0.5-1.2 mg / L.

[0074] More preferably, in step (2), the stirring conditions must at least satisfy: a rotation speed of 300-600 s. -1 The time is 5-15 seconds.

[0075] In a preferred embodiment, the dosage of the metal-based supported catalyst-loading medium material is 3-5 g / L.

[0076] Preferably, in step (3), the oxidant is 0.05-0.07mM potassium ferrate and 0.5-0.7mM sodium hypochlorite, with both potassium ferrate and sodium hypochlorite being added as oxidants simultaneously.

[0077] More preferably, the stirring conditions during the preparation of water body III meet the following requirements: rotation speed of 165-275 s. -1 The duration is 60s-180s.

[0078] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the raw materials are all commercially available products.

[0079] In the following examples, unless otherwise specified, the polyethersulfone filter membrane has a specification of Φ50mm and an average pore size of 0.45μm.

[0080] Example 1

[0081] This embodiment combines Figure 1 A method for enhanced treatment of rainwater overflow wastewater based on transition metal modified microsand is provided, comprising the following steps:

[0082] (1) The overflow sewage (flow rate of 70m) 3 The mixture is transported to the coagulation tank at a rate of / h, and 4 mg / L aluminum sulfate (calculated as aluminum) is added to it. The mixture is then reacted at 600s. -1 Stirring for 60 seconds under the specified conditions yields water body I.

[0083] The overflow wastewater is first treated as follows: it is passed through a coarse screen with a mesh size of 50 mm and a fine screen with a mesh size of 10 mm in sequence to remove visible debris such as floating matter. The overflow wastewater contains dissolved organic matter, which includes humic substances, proteins, lipids, etc., and the concentration of the dissolved organic matter is 24.37 mg / L. The ammonia nitrogen concentration in the overflow wastewater is 11.95 mg / L.

[0084] (2) Transport the water body I described in step (1) to the dosing tank, add 1 mg / L 15,000,000 Da polyacrylamide to the dosing tank, and react it at 600 s. -1 Stirring for 10 seconds under the specified conditions, then adding 3 g / L of iron-based supported catalyst-loading medium material to the addition tank, and stirring for 600 seconds. -1 Under the specified conditions, stirring for 10 seconds yielded water body II.

[0085] The iron-based supported catalyst-loading medium material is prepared by the following method:

[0086] S1: Soak 100g of quartz sand in 500mL of 10wt% hydrochloric acid for 24h, then rinse it with ultrapure water until the pH of the rinsing water is close to neutral, and then dry the quartz sand in an oven at 100℃ for 3h and store it for later use.

[0087] S2: Dissolve ferric nitrate nonahydrate in ultrapure water to prepare a 400 mL 0.1 M metal salt solution, add 100 g quartz sand, stir at 50 °C for 6 h, add alkaline solution dropwise to adjust the pH of the solution to alkaline (the temperature must be kept constant at this time), and stir for 30 min.

[0088] S3: After aging in a water bath at 65℃ for 12 hours, solid-liquid separation was performed. The solid phase was then dried in an oven at 100℃ and ground until the particle size was 80-150μm.

[0089] S4: The dried material was placed in a muffle furnace and calcined at 450°C for 3 hours to obtain an iron-based supported catalyst-loading medium material.

[0090] (3) The water body II is transported to the flocculation tank and precipitated for 200 seconds. -1 Under the specified conditions, stir for 60 seconds, then add 0.6 mM sodium hypochlorite and 0.054 mM potassium ferrate to the flocculation tank, and stir for 200 seconds. -1 Stirring under these conditions for 60 seconds yields water body III.

[0091] (4) The water body III is transported to a sedimentation tank for static sedimentation treatment for 1 minute, so that the flocs and iron-based supported catalyst-loaded sludge settle to the bottom and obtain supernatant water.

[0092] (5) The precipitated iron-based supported catalytic-loaded sludge enters the magnetic separator, where the magnetic loading medium is effectively separated and recovered through the action of a magnetic field. The recovered medium is then pumped back to the addition tank for reuse.

[0093] Example 2

[0094] The method of Example 1 was followed, except that in step (2), 3 g / L of copper-based supported catalyst-loading medium was added. In the preparation of the copper-based supported catalyst-loading medium, the metal salt used was a 0.1 M copper nitrate trihydrate solution. The remaining steps and parameters were the same as in Example 1.

[0095] Example 3

[0096] The method of Example 1 was followed, except that in step (2), 3 g / L of nickel-based supported catalyst-loading medium was added. The metal salt used in the preparation of the nickel-based supported catalyst-loading medium was a 0.1 M nickel nitrate hexahydrate solution. The remaining steps and parameters were the same as in Example 1.

[0097] Example 4

[0098] The method of Example 1 was followed, except that in step (2), 3 g / L of iron-copper based bimetallic supported catalyst-loading medium was added. In the preparation of the iron-copper based supported catalyst-loading medium, the metal salts selected were ferric nitrate nonahydrate and copper nitrate trihydrate, the total concentration of metal ions was 0.1 M, and the concentrations of iron and copper ions were 0.05 M, respectively. The remaining steps and parameters were the same as in Example 1.

[0099] Example 5

[0100] The method of Example 1 was followed, except that in step (2), 3 g / L of iron-nickel based bimetallic supported catalyst-loading medium was added. In the preparation of the iron-nickel based supported catalyst-loading medium, the metal salts selected were ferric nitrate nonahydrate and nickel nitrate hexahydrate, the total concentration of metal ions was 0.1 M, and the concentrations of iron and nickel ions were 0.05 M, respectively. The remaining steps and parameters were the same as in Example 1.

[0101] Example 6

[0102] The method of Example 1 was followed, except that in step (2), 3 g / L of copper-nickel based bimetallic supported catalyst-loading medium was added. In the preparation of the copper-nickel based supported catalyst-loading medium, copper nitrate trihydrate and nickel nitrate hexahydrate were selected as the metal salts. The total concentration of metal ions was 0.1 M, and the concentrations of copper and nickel ions were 0.05 M, respectively. The remaining steps and parameters were the same as in Example 1.

[0103] Comparative Example 1

[0104] The procedure was carried out according to the method of Example 1, except that in step (2), 3 g / L of unmodified quartz sand was added, and the remaining steps and parameters were the same as in Example 1.

[0105] Comparative Example 2

[0106] This comparative example provides a method for treating overflow wastewater by prior oxidation followed by coagulation, the method comprising the following steps:

[0107] (1) The overflow sewage (flow rate of 70m) 3 The solution is transported to the oxidation tank at a rate of / h, and 0.6 mM sodium hypochlorite and 0.054 mM potassium ferrate (calculated as Fe(VI)) are added to it. The solution is then reacted at 600s. -1 Stirring for 60 seconds under the specified conditions yields water body I.

[0108] The overflow wastewater is first treated as follows: it is passed through a coarse screen with a mesh size of 50 mm and a fine screen with a mesh size of 10 mm in sequence to remove visible debris such as floating matter. The overflow wastewater contains dissolved organic matter, which includes humic substances, proteins, lipids, etc., and the concentration of the dissolved organic matter is 24.37 mg / L. The ammonia nitrogen concentration in the overflow wastewater is 11.95 mg / L.

[0109] (2) The water body I is transported to the coagulation tank and 4 mg / L aluminum sulfate (calculated as aluminum) is added to it. The mixture is then stirred for 600 seconds. -1 Stirring for 60 seconds under the specified conditions yields water body II.

[0110] (3) The water body II is transported to the dosing tank, and 1 mg / L 15,000,000 Da polyacrylamide is added to the dosing tank, and the solution is dissolved in water for 600 seconds. -1 Stirring for 10 seconds under the specified conditions, then adding 3 g / L of iron-based supported catalyst-loading medium material (preparation method as in Example 1) to the addition tank, and stirring for 600 seconds. -1 Under the specified conditions, stirring for 10 seconds yielded water body III;

[0111] (4) The water body III is transported to the flocculation tank and flocculated for 200 seconds. -1 Stirring for 60 seconds under the specified conditions yielded water body IV;

[0112] (5) The water body IV is transported to a sedimentation tank (containing supernatant and iron-based supported catalyst-loaded medium sludge) for static sedimentation treatment for 1 minute, so that the flocs and iron-based supported catalyst-loaded medium sludge settle to the bottom and supernatant is obtained;

[0113] (6) The precipitated iron-based supported catalytic-loaded sludge enters the magnetic separator, where the magnetic loading medium is effectively separated and recovered through the action of a magnetic field. The recovered medium is then pumped back to the addition tank for reuse.

[0114] Comparative Example 3

[0115] The procedure was carried out according to Comparative Example 2, except that in step (3), 3 g / L of copper-based supported catalyst-loading medium was added, and the remaining steps and parameters were the same as in Comparative Example 2.

[0116] Comparative Example 4

[0117] The procedure was carried out according to Comparative Example 2, except that in step (3), 3 g / L of nickel-based supported catalyst-loading medium was added, and the remaining steps and parameters were the same as in Comparative Example 2.

[0118] Comparative Example 5

[0119] The method was carried out in accordance with Comparative Example 2, except that in step (3), 3 g / L of iron-copper based bimetallic supported catalyst-loading medium was added. The remaining steps and parameters were the same as in Comparative Example 2.

[0120] Comparative Example 6

[0121] The method was carried out in accordance with Comparative Example 2, except that in step (3), 3 g / L of iron-nickel based bimetallic supported catalyst-loading medium was added. The remaining steps and parameters were the same as in Comparative Example 2.

[0122] Comparative Example 7

[0123] The procedure was carried out according to Comparative Example 2, except that in step (3), 3 g / L of copper-nickel based bimetallic supported catalyst-loading medium was added. The remaining steps and parameters were the same as in Comparative Example 2.

[0124] Table 1

[0125]

[0126] As can be seen from the results in Table 1, compared with coagulation oxidation without the use of modified microsand (Comparative Example 1), the method of this embodiment can remove dissolved organic matter and ammonia nitrogen in a short time. Specifically, in Comparative Example 1, the removal rate of dissolved organic matter was negative, which may be due to the desorption of organic matter on suspended particles caused by oxidation, resulting in an increase in dissolved organic matter after treatment.

[0127] Based on the results in Table 1, overall, the coagulation followed by oxidation (Examples 1-6) showed higher removal rates of soluble organic matter and ammonia nitrogen than the oxidation followed by coagulation (Comparative Examples 2-7).

[0128] Combination Figure 2 The removal of organic matter with different molecular weights from overflow wastewater by different catalytic-loading media was compared. The peak area ratios of organic matter with molecular weights between 0.1 kDa and 1.0 kDa after treatment with iron, copper, nickel, iron-copper, iron-nickel, and copper-nickel-based supported catalytic-loading media were 1:1.13:1.48:2.33:1.82:1.66. Compared with the use of bimetallic supported catalytic-loading media (Examples 4-6), the single-metal supported catalytic-loading media (Examples 1-3) showed better control of small molecule organic matter.

[0129] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for enhanced treatment of rainwater overflow wastewater based on transition metal modified microsand, characterized in that, Includes the following steps: The overflow sewage during the rainy season and the coagulant were added to the coagulation tank and mixed to obtain water body I; Water body I is transported to a dosing tank, coagulant is added and stirred, then metal-based supported catalyst-loading medium material is added, and the mixture is stirred to obtain water body II; Water body II is transported to a flocculation tank and stirred. An oxidant is added and stirred to obtain water body III. The water body III is transported to a sedimentation tank for sedimentation treatment to obtain supernatant water and precipitated sludge containing metal-based supported catalyst-loading medium material; the obtained precipitated sludge is recovered by magnetic separation, and the metal-based supported catalyst-loading medium material is reused in the addition tank to achieve reuse; The metal-based supported catalyst-loading medium material was prepared by the following method: S1: Soak the quartz sand in an acid solution, clean and dry it for later use; S2: Add quartz sand to the metal salt solution, sonicate, then stir for the first time for 5-6 hours, adjust the solution to alkaline, and continue stirring for the second time to obtain the reaction mixture; S3: The resulting reaction mixture is aged, then solid-liquid separation is performed and the solid phase is collected. The obtained solid phase is calcined to obtain a metal-based supported catalyst-loading medium material; In step S2, the concentration of the metal salt solution is 0.1M; The metal salt is selected from any two of iron, copper and nickel; the concentration ratio of any two metal ions is 1:

1. The salt in the metal salt is selected from one or more of nitrates, sulfates and chlorides; In step S3, the calcination temperature is 400-600℃, the calcination time is 2-5h, and the heating rate is 5-10℃ per minute.

2. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, The coagulant is selected from one or more of aluminum sulfate, ferric chloride, polyferric sulfate, and polyaluminum chloride; The dosage of the coagulant is 2.5-5.5 mg / L.

3. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, The coagulant is selected from polyacrylamide and / or starch-based polymers; The dosage of the coagulant is 0.5-1.2 mg / L.

4. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, The dosage of the metal-based supported catalyst-loading medium material is 3-5 g / L.

5. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, In step S1, the acid in the acid solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, and oxalic acid. The concentration of the acid solution is 5-10 wt%; Soaking time is 12-24 hours.

6. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, In step S2, the frequency of ultrasound is 40-50Hz, the ultrasound time is 20-30min, and the temperature is 25-35℃. The first stirring time is 5-6 hours, and the temperature is 50-60℃; The second stirring time is 20-30 minutes, and the temperature is 50-60℃.

7. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, In step S3, the aging temperature is 50-65℃ and the aging time is 12-24h.

8. The method for enhanced treatment of rainy season overflow sewage based on transition metal modified microsand according to claim 1, characterized in that, The oxidant includes potassium ferrate and sodium hypochlorite, and the molar concentration ratio of potassium ferrate and sodium hypochlorite is (0.05-0.07):(0.5-0.7).

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