Sewage treatment agent preparation method, sewage treatment method and sewage treatment device

Abstract

The invention discloses a sewage treatment agent preparation method and a sewage treatment method and device, and relates to the technical field of sewage treatment. The preparation method of the sewage treatment agent comprises the following steps: step 1, grinding steel slag until the particle size is 0.1-2.5 mm; 2, dilute sulphuric acid with the concentration of 5%-20% is added into the reaction tank according to the solid-to-liquid ratio of 1 kg: (8-15) L, and a reaction is conducted for 50-7 min under stirring at the temperature of 20-25 DEG C and the speed of 150-200 rpm. By adopting the technical scheme, ferrous sulfate and polyaluminum chloride are replaced by the steel slag, so that the steel slag is reutilized with high value, the addition of sewage treatment chemicals is reduced, and the output of sludge is reduced; indissolvable solid residues in the steel slag are dehydrated into calcium sulfate dihydrate, calcium silicate and amorphous silicon dioxide which can be used as building raw materials, secondary pollution caused by the building raw materials is avoided, and the value of the steel slag is fully exerted.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for preparing wastewater treatment agents, a wastewater treatment method, and an apparatus. Background Technology

[0002] Traditionally, steel slag is mainly reused in the building materials industry as a raw material for cement, concrete aggregates, and steel slag bricks. However, the amount of steel slag used is limited, with hundreds of millions of tons still stockpiled nationwide. Moreover, the added value of steel slag is low, and the iron and aluminum metal oxides in it are not fully utilized.

[0003] Currently, there is some research on the resource utilization of steel slag in the field of wastewater treatment. For example, patent CN101353201A uses steel slag as an adsorbent filler. However, the steel slag after utilization will form solid waste, which still needs to be treated separately, increasing the cost of use. For example, patent CN1262233A uses steel slag mixed with other substances and then crushed and ground to make a coagulant. However, after use, the insoluble substances in the steel slag will be converted into sludge for wastewater treatment. The amount of sludge is large, which will increase the treatment cost.

[0004] In addition, the traditional Fenton process in wastewater treatment has two major drawbacks: First, the cost of chemicals accounts for a high proportion (about 25-30 yuan / m³ for conventional processes); second, excessive iron salt addition leads to an increase in sludge production of more than 30%.

[0005] Therefore, for the resource utilization of steel slag, there is an urgent need for a new technology that uses steel slag as a wastewater treatment agent without generating secondary pollution and reducing sludge volume, so that the utilization of steel slag can play a greater economic and environmental role. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing a method for preparing wastewater treatment agents, a wastewater treatment method, and an apparatus. By replacing ferrous sulfate and polyaluminum chloride with steel slag, the high-value reuse of steel slag is achieved while reducing the amount of wastewater treatment agents added and the amount of sludge generated, thus achieving the goal of "treating waste with waste." At the same time, the insoluble solid residues in the steel slag are dehydrated into calcium sulfate dihydrate, calcium silicate, and amorphous silica, which can be used as building materials, avoiding secondary pollution and fully utilizing the value of steel slag.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing a wastewater treatment agent, comprising: In a first aspect, the present invention provides a method for preparing a wastewater treatment agent, characterized by comprising the following steps: Step 1: Grind the steel slag to a particle size of 0.1-2.5 mm; Step 2: Add 5%-20% dilute sulfuric acid to the reaction vessel at a solid-liquid ratio of 1kg:(8-15)L, and react for 50-70 minutes at 20-25℃ and 150-200rpm with stirring. Step 3: Allow the mixture to stand until the turbidity of the upper liquid is ≤10 NTU, then separate the Fe-containing liquid. 2+ / A1 3+ The supernatant and solid residue.

[0008] Optionally, the supernatant contains Fe 2+ Concentration ≥ 5 g / L, used as Fenton reaction reagent.

[0009] Optionally, the solid residue, after being dehydrated by pressure filtration, includes at least one of calcium sulfate dihydrate, calcium silicate, and amorphous silica, conforming to the GB / T 28634-2012 building materials standard.

[0010] Secondly, the present invention provides a wastewater treatment method based on the resource utilization of steel slag, characterized by comprising the following steps: (a) Acid dissolution treatment of steel slag: Steel slag is mixed with dilute sulfuric acid with a concentration of 5%-20% at a solid-liquid ratio of 1kg:(8-15)L and reacted at 20-25℃ and a stirring speed of 150-200rpm for 50-70min. After standing for 30min, the supernatant and solid residue are separated. (b) First-stage Fenton reaction: The supernatant and wastewater are introduced into the first-stage reaction tank at a volume ratio of (1-10):1000, 30% hydrogen peroxide solution is added, pH is controlled at 2.5-3.0, and the reaction time is 50-70 min; (c) Neutralization and precipitation: The effluent from the primary reaction tank is introduced into the secondary reaction tank, and a 10% sodium hydroxide solution is added to adjust the pH to 7.0-8.0; (d) Flocculation enhancement: The effluent from the secondary reaction tank is introduced into the tertiary reaction tank, and 0.05%-0.1% polyacrylamide solution is added to the tertiary reaction tank. The wastewater after the reaction is introduced into the sedimentation tank, and the effluent is discharged after the sludge and water are separated in the sedimentation tank.

[0011] Optionally, in step (a), the steel slag has a particle size of 0.1-2.5 mm and contains silicon dioxide and calcium oxide, with the total content of silicon dioxide and calcium oxide being ≥50 wt%.

[0012] Optionally, in step (b), the supernatant Fe 2+ The concentration is ≥5g / L, and the volume ratio of the supernatant to hydrogen peroxide is (1-5):1.

[0013] Optionally, the solid residue obtained in step (a), after being dehydrated by pressure filtration, shall include at least one of calcium sulfate dihydrate, calcium silicate, and amorphous silica, and shall have a 28-day compressive strength ≥20MPa, conforming to the GB / T 28634-2012 standard for recycled aggregates for construction.

[0014] Optionally, the supernatant is prepared by mixing it with 30% hydrogen peroxide at a volume ratio of (1-3):1, wherein Fe 2 + The molar ratio of H2O2 is (0.8-1.2):1.

[0015] Thirdly, the present invention provides a wastewater treatment agent preparation and wastewater treatment apparatus, comprising: a reaction tank, a filter press, a primary reaction tank, a secondary reaction tank, a tertiary reaction tank, and a sedimentation tank. A agent pump for extracting supernatant is installed between the reaction tank and the primary reaction tank, and a stirring device is installed in each of the reaction tank, the primary reaction tank, the secondary reaction tank, and the tertiary reaction tank. A filter cake pump for extracting solid residue is installed between the lower end of the reaction tank and the feed end of the filter press. The primary reaction tank, the secondary reaction tank, the tertiary reaction tank, and the sedimentation tank are also included.

[0016] Optionally, both the primary and secondary reaction tanks are equipped with online pH meters.

[0017] After adopting the above technical solution, the beneficial effects of the present invention are as follows: This invention replaces ferrous sulfate and polyaluminum chloride with steel slag, enabling the high-value reuse of steel slag while reducing the dosage of wastewater treatment agents and the amount of sludge generated, achieving the goal of "treating waste with waste." Simultaneously, the insoluble solid residues of silica and calcium oxide in the steel slag are further dehydrated using a filter press to form calcium sulfate dihydrate, calcium silicate, and amorphous silica, which can be used as building materials, avoiding secondary pollution and fully realizing the value of the steel slag.

[0018] Industrial waste residue is converted into a highly efficient water treatment agent through a low-temperature acid dissolution-gradient reaction process. This utilizes the Fe content in steel slag. 2+ / Al 3+ The controlled release achieves a Fenton-like reaction; simultaneously solving the problems of high reagent costs and large sludge production in traditional processes. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the main cross-sectional structure of the device of the present invention.

[0021] Explanation of reference numerals in the attached diagram: 1. Reaction tank; 2. Online pH meter; 3. Filter press; 4. Stirring device; 5. Reagent pump; 6. Filter residue pump; 7. Primary reaction tank; 8. Secondary reaction tank; 9. Tertiary reaction tank; 10. Sedimentation tank. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0024] This embodiment relates to a method for preparing a wastewater treatment agent, such as... Figure 1 As shown, it includes the following steps: Step 1: Grind the steel slag to a particle size of 0.1-2.5 mm; Step 2: Add 5%-20% dilute sulfuric acid to the reaction vessel at a solid-liquid ratio of 1kg:(8-15)L, and react for 50-70 minutes at 20-25℃ and 150-200rpm with stirring. Step 3: Allow the mixture to stand until the turbidity of the upper liquid is ≤10 NTU, then separate the Fe-containing liquid. 2+ / A1 3+ The supernatant and solid residue, Fe in the supernatant 2+ With a concentration ≥5g / L, it is used as a Fenton reaction reagent. After dehydration by pressure filtration, the solid residue contains at least one of calcium sulfate dihydrate, calcium silicate, and amorphous silica, conforming to the GB / T 28634-2012 building materials standard.

[0025] In this embodiment, the first step is to pretreat the steel slag. Steel slag from a steel plant's converter (chemical composition: FeO 32.5%, CaO 38.2%, SiO2 18.7%, with the remainder being Al2O3 and MgO) is taken, crushed by a jaw crusher, and then ground to a particle size of 0.1-2.5 mm (D90 ≤ 2.5 mm) by a ball mill. The second step is an acid dissolution reaction, carried out in an effective volume of 2 m³. 3100 kg of steel slag was added to a corrosion-resistant reaction vessel 1, and 10% dilute sulfuric acid (H2SO4 mass fraction, prepared by diluting 98% concentrated sulfuric acid) was added at a solid-liquid ratio of 1 kg:10 L. Stirring device 4 (180 rpm) was turned on. Stirring device 4 is existing technology. The reaction was carried out at 20℃ and normal pressure for 60 min. In the third step, after the reaction was completed, the mixture was allowed to stand for 30 min, and the supernatant (turbidity 8.2 NTU) and solid residue were separated. Supernatant parameters: ICP-OES analysis showed Fe... 2+ Concentration 6.2 g / L, Al 3+ The concentration is 1.8 g / L and the pH is 2.8, which meets the requirements of Fenton's reagent.

[0026] Solid residue treatment: The filter residue pump 6 transports the solid residue to the filter press 3, where it is dehydrated and the moisture content is ≤20%. XRD analysis shows that the main phases of the residue are calcium sulfate dihydrate (CaSO4·2H2O, content ≥65%), calcium silicate (CaSiO3, content ≥20%), and amorphous silica (content ≥10%). Its 28-day compressive strength reaches 22MPa, which meets the Class II material standard in GB / T 28634-2012 "Recycled Fine Aggregate for Concrete and Mortar".

[0027] In a wastewater treatment experiment, taking the wastewater from a lithium battery factory (COD=4780mg / L, pH=6.5, flow rate 1000L / h) as an example, Scheme 1 is the traditional process, and Scheme 2 is the process of this invention. It should be noted that the following schemes utilize a primary reaction tank 7, a secondary reaction tank 8, a tertiary reaction tank 9, and a sedimentation tank 10, which are connected sequentially with a liquid level difference. Each of these tanks has a water passage hole (not shown), and a solenoid valve (not shown) is installed in the water passage hole. A comparison of Scheme 1 and Scheme 2 is as follows: Option 1: Under normal temperature and pressure, turn on the stirring device 4 in each stage of the reaction tank for stirring. Flow wastewater into the first-stage reaction tank 7 at a flow rate of 1000 L / h. Add 6 L / h of 10% sulfuric acid to the first-stage reaction tank 7 to adjust the pH of the wastewater to 3.0. Then add 50 L / h of 5% ferrous sulfate solution, followed by 9 L / h of 30% hydrogen peroxide solution. The reaction residence time is 1 hour under normal temperature and pressure. After that, open the solenoid valve and introduce the wastewater into the second-stage reaction tank 8 through the water passage. Add 13.5 L / h of 10% sodium hydroxide solution to adjust the pH of the wastewater to 8.0. Then add 5 L / h of 5% polyaluminum chloride solution until fine flocs are produced. Then add 1 L / h of 0.1% polyacrylamide solution. After the reaction residence time is 30 minutes, open the solenoid valve and introduce the wastewater into the sedimentation tank 10 through the water passage for settling. The COD of the supernatant was measured to be 2995 mg / L (measured according to the national standard HJ828-2017). After 1 hour of reaction, the sludge from the sedimentation tank was taken and filtered through a filter paper with a pore size of 50 micrometers. The weight of the sludge was measured to be 802 g by drying.

[0028] Option 2: Under normal temperature and pressure, start the agitators in each stage of the reaction tank for stirring. Introduce wastewater into the primary reaction tank at a flow rate of 1000 L / h. Pump 10 L / h of steel slag supernatant into the primary reaction tank 7 via the reagent pump 5 connected to reaction tank 1, measuring the pH value to 2.75. Then, open the solenoid valve and introduce the wastewater into the secondary reaction tank 8 through the water passage. Add 9 L / h of 30% hydrogen peroxide solution. React for 1 hour under normal temperature and pressure. Afterward, add 5 L / h of 10% sodium hydroxide solution to adjust the wastewater pH to 7.0. The wastewater then flows into the tertiary reaction tank 9, where 1 L / h of 0.1% polyacrylamide solution is added. After the reaction has been held for 30 minutes, the solenoid valve is opened, and the wastewater is introduced into the sedimentation tank 10 through the water passage for settling. The supernatant is taken, and the COD is measured to be 2990 mg / L (measured according to the national standard HJ828-2017). After the reaction has been held for 1 hour, the sludge from the sedimentation tank is taken and filtered through a 50-micron pore size filter paper. The sludge weight is measured to be 593 g by the drying method.

[0029] This experiment calculates the cost of pharmaceuticals based on the following drug prices: 98% sulfuric acid - 1.96 yuan / kg; Ferrous sulfate - 1.0 yuan / kg; 30% hydrogen peroxide - 1.95 yuan / kg; Sodium hydroxide - 4.3 yuan / kg; Polyaluminum chloride - 1.75 yuan / kg; Polyacrylamide - 6.5 yuan / kg; Steel slag - 0.2 yuan / kg The processing effect is verified, as shown in the table below:

[0030] Conclusion: This embodiment realizes the high-value utilization of steel slag, significantly reducing operating costs and secondary pollution while ensuring treatment effect.

[0031] In another wastewater treatment experiment, taking the wastewater from a dyeing and printing factory (COD=2200mg / L, pH=6.5, flow rate 1000L / h) as an example, Scheme 3 is the traditional process, and Scheme 4 is the process of this invention. The comparison between Scheme 3 and Scheme 4 is as follows: Option 3: Under normal temperature and pressure, activate the stirring device 4 in each stage of the reaction tank for stirring. Introduce wastewater into the primary reaction tank 7 at a flow rate of 1000 L / h. Add 11.5 L / h of 10% sulfuric acid to the primary reaction tank 7 to adjust the pH of the wastewater to 3.0. Then add 45 L / h of 5% ferrous sulfate solution, followed by 7 L / h of 30% hydrogen peroxide solution. Maintain the reaction residence time at normal temperature and pressure for 1 hour. Afterward, open the solenoid valve and introduce the wastewater into the secondary reaction tank through the water passage. In tank 8, 10.5 L / h of 10% sodium hydroxide solution was added to adjust the pH of the wastewater to 8.0. Then, 3.5 L / h of 5% polyaluminum chloride solution was added until fine flocs formed. Next, 0.8 L / h of 0.1% polyacrylamide solution was added. After the reaction was allowed to proceed for 30 minutes, the solenoid valve was opened, and the wastewater was introduced into sedimentation tank 10 through the water passage for settling. The COD of the supernatant was measured to be 880 mg / L (measured according to the national standard HJ828-2017). After 1 hour of reaction, the sludge from the sedimentation tank was collected and filtered through 50-micron filter paper. The sludge weight was measured to be 636 g by drying.

[0032] Option 4: Under normal temperature and pressure, activate the stirring device 4 in each stage of the reaction tank for stirring. Introduce wastewater into the primary reaction tank 7 at a flow rate of 1000 L / h. Pump 8 L / h of steel slag supernatant into the primary reaction tank 7 via the reagent pump 5 connected to reaction tank 1, measuring a pH of 2.8. Then, open the solenoid valve and introduce the wastewater into the secondary reaction tank 8 through the water passage. Add 7 L / h of 30% hydrogen peroxide solution. React for 1 hour under normal temperature and pressure. Afterward, add 4.8 L / h of 10% sodium hydroxide solution to adjust the pH of the wastewater to 7.0. Then, open the solenoid valve and introduce the wastewater into the tertiary reaction tank 9 through the water passage. Add 0.8 L / h of 0.1% polyacrylamide solution. After a 30-minute reaction period, open the solenoid valve and introduce the wastewater into the sedimentation tank 10 through the water passage for settling. Take the supernatant; the measured COD is 873 mg / L. After 1 hour of reaction, sludge from the sedimentation tank was taken and filtered through filter paper with a pore size of 50 micrometers. The weight of the sludge was measured to be 475g by drying method.

[0033] The processing effect is verified, as shown in the table below:

[0034] Conclusion: This embodiment verifies the economic and environmental advantages of steel slag-based agents in the treatment of dyeing and printing wastewater, and simplifies the process (reducing the polyaluminum chloride addition step).

[0035] Industrial waste residue is converted into a highly efficient water treatment agent through a low-temperature acid dissolution-gradient reaction process. The core innovation of this invention lies in: (1) utilizing Fe in steel slag 2+ / Al 3+ (1) Controllable release achieves Fenton-like reaction; (2) Simultaneously solves the problems of high reagent cost and large sludge production in traditional processes. Experiments show that when treating lithium battery wastewater, reagent cost is reduced by 20.3% and sludge volume is reduced by 26.0%; when treating dyeing and printing wastewater, cost is reduced by 20.1% and sludge volume is reduced by 25.3%.

[0036] This invention also provides a wastewater treatment method based on the resource utilization of steel slag, comprising the following steps: (a) Acid dissolution treatment of steel slag: Steel slag is mixed with dilute sulfuric acid of 5%-20% concentration at a solid-liquid ratio of 1kg:(8-15)L and reacted at 20-25℃ and stirring speed of 150-200rpm for 50-70min. After standing for 30min, the supernatant and solid residue are separated. The steel slag has a particle size of 0.1-2.5mm and contains silicon dioxide and calcium oxide, with a total content of silicon dioxide and calcium oxide ≥50wt%. After dewatering by pressure filtration, the obtained solid residue contains at least one of calcium sulfate dihydrate, calcium silicate, and amorphous silicon dioxide. The compressive strength after 28 days is ≥20MPa, which meets the GB / T 28634-2012 standard for recycled aggregates for construction. (b) First-stage Fenton reaction: The supernatant and wastewater are introduced into the first-stage reaction tank 7 at a volume ratio of (1-10):1000, and 30% hydrogen peroxide solution is added to control the pH at 2.5-3.0. The reaction time is 50-70 min; the Fe in the supernatant... 2+ The concentration is ≥5 g / L, and the volume ratio of the supernatant to hydrogen peroxide is (1-5):1; the supernatant and 30% hydrogen peroxide are mixed at a volume ratio of (1-3):1, wherein Fe 2+ The molar ratio of H2O2 is (0.8-1.2):1; (c) Neutralization and precipitation: The effluent from the primary reaction tank 7 is introduced into the secondary reaction tank 8, and a 10% sodium hydroxide solution is added to adjust the pH to 7.0-8.0; (d) Flocculation enhancement: The effluent from the secondary reaction tank 8 is introduced into the tertiary reaction tank 9. 0.05%-0.1% polyacrylamide solution is added to the tertiary reaction tank 9. After the reaction, the solenoid valve is opened and the wastewater is introduced into the sedimentation tank 10 through the water passage. After the sedimentation tank 10 separates the mud and water, the wastewater is discharged.

[0037] The wastewater treatment method of the present invention has been described in detail in the above embodiments. Referring to the wastewater treatment embodiments of lithium battery factories and dyeing and printing factories, it will not be repeated here. The advantages of the present invention are: 1. Adopt a dual-effect synergistic mechanism: FeO (≥30wt%) in steel slag reacts with dilute sulfuric acid to produce FeSO4, which replaces purchased ferrous sulfate; Undissolved components such as CaSiO3 form a porous support, which adsorbs and co-precipitates heavy metals.

[0038] 2. Optimization of process parameters: A segmented pH control method is adopted: the first-stage reaction is pH=2.5-3.0 to ensure Fenton efficiency (the comprehensive performance of the Fenton reaction system in terms of the ability to oxidize and degrade pollutants and the efficiency of resource utilization under specific conditions), and the second-stage reaction is pH=7.0-8.0 to avoid colloid restabilization; The addition of polyaluminum chloride (coagulant) is reduced, and Al2(SO4)3 and Fe2(SO4)3 in the supernatant can replace polyaluminum chloride.

[0039] This invention also provides a wastewater treatment agent preparation and a wastewater treatment apparatus, such as... Figure 1 As shown, the system includes: a reaction tank 1, a filter press 3, a primary reaction tank 7, a secondary reaction tank 8, a tertiary reaction tank 9, and a sedimentation tank 10. A reagent pump 5 for extracting the supernatant is installed between the reaction tank 1 and the primary reaction tank 7. A stirring device 4 is installed in each of the reaction tank 1, the primary reaction tank 7, the secondary reaction tank 8, and the tertiary reaction tank 9. A filter residue pump 6 for extracting solid residue is installed between the lower end of the reaction tank 1 and the feed end of the filter press 3. An online pH meter 2 is installed in each of the primary reaction tank 7 and the secondary reaction tank 8.

[0040] The working principle of this embodiment is based on the wastewater treatment embodiments of lithium battery factories and dyeing factories, and will not be repeated here. This invention, by replacing ferrous sulfate and polyaluminum chloride with steel slag and combining it with this device, allows for the high-value reuse of steel slag while reducing the addition of wastewater treatment agents and the amount of sludge generated, achieving the goal of "treating waste with waste." Simultaneously, the insoluble solid residues of silica and calcium oxide in the steel slag are further dehydrated by the filter press 3 to form calcium sulfate dihydrate, calcium silicate, and amorphous silica, which can be used as building materials, avoiding secondary pollution and fully utilizing the value of the steel slag.

[0041] The above is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing a sewage treatment agent, characterized by comprising the steps of: 2+ ​ Step 1: grinding the steel slag to a particle size of 0.1-2.5 mm; Step 2: adding dilute sulfuric acid with a concentration of 5%-20% to the reaction tank at a solid-liquid ratio of 1 kg:(8-15) L, and reacting for 50-70 min under stirring at 20-25°C and a stirring speed of 150-200 rpm; Step three: static stratification to the upper liquid turbidity ≤ 10 NTU, separation of Fe 2+ / A1 3+ containing supernatant and solid residue.

2. The method according to claim 1, wherein: Fe in the supernatant 2+ Concentration > 5 g / L, used as Fenton reaction reagent.

3. The method for preparing a wastewater treatment agent according to claim 1, characterized in that: The solid residue, after dewatering by pressure filtration, at least comprises one of calcium sulfate dihydrate, calcium silicate and amorphous silicon dioxide, and meets the building material standard of GB / T 28634-2012.

4. A sewage treatment method based on steel slag resource utilization, characterized in that, The method comprises the following steps: (a) steel slag acid dissolution treatment: mixing the steel slag with dilute sulfuric acid with a concentration of 5%-20% at a solid-liquid ratio of 1 kg:(8-15) L, and reacting for 50-70 min under stirring at 20-25°C and a stirring speed of 150-200 rpm, and separating the supernatant and the solid residue after standing for 30 min; (b) primary Fenton reaction: introducing the supernatant and the wastewater into a primary reaction tank at a volume ratio of (1-10):1000, adding 30% hydrogen peroxide solution, controlling the pH to be 2.5-3.0, and reacting for 50-70 min; (c) neutralization and precipitation: introducing the effluent from the primary reaction tank into a secondary reaction tank, and adding 10% sodium hydroxide solution to adjust the pH to 7.0-8.0; (d) flocculation intensification: introducing the effluent from the secondary reaction tank into a tertiary reaction tank, adding 0.05%-0.1% polyacrylamide solution in the tertiary reaction tank, introducing the reacted wastewater into a sedimentation tank, and separating the effluent from the wastewater in the sedimentation tank.

5. The sewage treatment method based on steel slag resource utilization according to claim 4, characterized in that: In step (a), the particle size of the steel slag is 0.1-2.5 mm, and the steel slag contains silicon dioxide and calcium oxide, and the total content of the silicon dioxide and the calcium oxide is ≥50 wt%.

6. The sewage treatment method based on steel slag resource utilization according to claim 4, characterized in that: In step (b), the supernatant Fe 2+ concentration > 5 g / L, and the volume ratio of the supernatant to hydrogen peroxide is (1-5):

1.

7. The sewage treatment method based on steel slag resource utilization according to any one of claims 4-6, characterized in that: The solid residue obtained in step (a), after dewatering by pressure filtration, at least comprises one of calcium sulfate dihydrate, calcium silicate and amorphous silicon dioxide, and has a 28-day compressive strength ≥20 MPa, meeting the building recycled aggregate standard of GB / T 28634-2012.

8. The sewage treatment method based on steel slag resource utilization according to any one of claims 4-6, characterized in that: The supernatant is compounded with hydrogen peroxide with a concentration of 30% at a volume ratio of (1-3): 1, wherein Fe 2+ The molar ratio of Fe / H2O2 is (0.8-1.2):

1.

9. A sewage treatment agent manufacturing and sewage treatment device, characterized by comprising: a sewage treatment agent manufacturing device; and a sewage treatment device. It comprises: a reaction tank, a filter press, a primary reaction tank, a secondary reaction tank, a tertiary reaction tank and a sedimentation tank, a medicament pump for extracting the supernatant is installed between the reaction tank and the primary reaction tank, stirring devices are installed in the reaction tank, the primary reaction tank, the secondary reaction tank and the tertiary reaction tank, a filter residue pump for extracting the solid residue is installed between the lower end of the reaction tank and the feed end of the filter press, and the primary reaction tank, the secondary reaction tank, the tertiary reaction tank and the sedimentation tank.

10. A method for preparing a wastewater treatment agent according to claim 9, characterized in that: Online pH acidimeters are installed in the primary reaction tank and the secondary reaction tank.

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