HPPO wastewater treatment system and method

Abstract

The invention relates to the technical field of organic chemical industry wastewater, in particular to an HPPO wastewater treatment system and method, and the system comprises a pretreatment unit which is used for respectively carrying out oil removal and homogenization on HP wastewater and PO wastewater to obtain HPPO wastewater; the oxidation unit is used for removing part of biochemical oxygen demand in the HPPO wastewater by utilizing a catalytic oxidation effect; the biochemical treatment unit is used for removing part of biochemical oxygen demand in the effluent of the oxidation unit by utilizing biochemical action, and the biochemical oxygen demand removed by the biochemical treatment unit is greater than the biochemical oxygen demand removed by the oxidation unit; and the deep treatment unit is used for treating the refractory biochemical oxygen demand in the effluent of the biochemical treatment unit. Therefore, the problems that in the prior art, the preparation process of a catalyst is complex, the cost is high, a large amount of chemical sludge can be generated, iron ions and sulfate ions in treated water exceed the standard, and the treatment efficiency of HPPO wastewater is low are solved.

Description

Technical Field

[0001] This application relates to the technical field of organic chemical wastewater, and particularly relates to a HPPO wastewater treatment system and method. Background Art

[0002] The process of directly oxidizing propylene with hydrogen peroxide (H2O2) to produce propylene oxide (PO) (HPPO process) is an economical, energy-saving, green, and environmentally friendly propylene oxide production process. In addition to most of the process production wastewater being propylene oxide wastewater (abbreviated as PO wastewater), there is also a small part of acidic wastewater containing residual hydrogen peroxide (abbreviated as HP wastewater).

[0003] Among them, the characteristics of PO wastewater are that it contains a large amount of alcohol by-products and a small amount of ethers, aldehydes, ketones, methoxyalkanes, etc., with extremely high organic matter concentration and general biodegradability; HP wastewater contains a certain concentration of residual hydrogen peroxide, by-products such as anthrone, hydroxyanthrone, and anthrahydroquinone generated during the hydrogenation stage of the anthraquinone method for producing H2O2, and by-products such as epoxyanthraquinone generated during the oxidation stage, heavy aromatic hydrocarbons, trioctyl phosphate, and 2-methylcyclohexyl acetate used as solvents, and macromolecular organic matters such as 2-ethylanthraquinone used as an alkyl anthraquinone carrier, with poor biodegradability.

[0004] In related technologies, the treatment methods and systems for HPPO wastewater have the following defects:

[0005] 1. The production process of the Fenton catalyst used in the Fe / C reduction Fenton oxidation process is complex and costly, which is not conducive to industrialization promotion; 2. The main method for removing COD by Fenton oxidation requires adding a large amount of oxidants, catalysts, acid-base regulators, flocculants, etc., which will generate a large amount of chemical sludge, and problems such as excessive iron ions and sulfate ions in the treated water, which have an adverse impact on subsequent biochemical reactions; 3. The treatment efficiency of HPPO wastewater is not high, and the chemical oxygen demand of the effluent is above 500 mg / L, and further in-depth treatment is still required. Summary of the Invention

[0006] This application provides a HPPO wastewater treatment system and method to solve the problems in related technologies such as the complex production process and high cost of the catalyst, the generation of a large amount of chemical sludge, the excessive iron ions and sulfate ions in the treated water, and the low treatment efficiency of HPPO wastewater.

[0007] The first aspect embodiment of the present application provides an HPPO wastewater treatment system, including: a pretreatment unit that removes oil and homogenizes HP wastewater and PO wastewater respectively to obtain HPPO wastewater; an oxidation unit that uses catalytic oxidation to remove part of the biochemical oxygen demand in the HPPO wastewater; a biochemical treatment unit that uses biochemical action to remove part of the biochemical oxygen demand in the effluent of the oxidation unit, wherein the biochemical oxygen demand removed by the biochemical treatment unit is greater than that removed by the oxidation unit; and a deep treatment unit that treats the refractory biochemical oxygen demand in the effluent of the biochemical treatment unit.

[0008] Optionally, the biochemical oxygen demand removed by the oxidation unit accounts for 14% - 17% of the total removed biochemical oxygen demand, the biochemical oxygen demand removed by the biochemical treatment unit accounts for 82% - 84% of the total removed biochemical oxygen demand, and the biochemical oxygen demand removed by the deep treatment unit accounts for 1.5% - 2% of the total removed biochemical oxygen demand.

[0009] Optionally, the pretreatment unit includes a flotation tank using flotation oil removal technology and a homogenization and regulation tank. Among them, the homogenization and regulation tank is located downstream of the flotation tank. The homogenization and regulation tank stores the PO wastewater to be treated. The HP wastewater removes floating oil through the flotation tank and enters the homogenization and regulation tank to be homogenized and mixed with the PO wastewater to be treated to obtain HPPO wastewater.

[0010] Optionally, the oxidation unit is provided with a Fenton catalytic oxidation reactor, and the Fenton catalytic oxidation reactor is used to moderately remove the biochemical oxygen demand in the HPPO wastewater by Fenton.

[0011] Optionally, the Fenton catalytic oxidizer includes an acid adjustment area, a catalytic oxidation area, a neutralization area, and a flocculation and precipitation area. Among them, the pH in the acid adjustment area is adjusted to 3 - 4, the dosage of the oxidant in the catalytic oxidation area is 3000 - 3200 mg / L, the dosage of the catalyst FeSO4 is 1300 - 1400 mg / L, the pH in the neutralization area is adjusted to 9 - 10, and the residence time is 2 h - 4 h.

[0012] Optionally, the biochemical treatment unit sequentially includes, according to the process flow: an anaerobic pretreatment reactor, an EIC anaerobic reactor, and a HEBR biochemical pool. Among them, the volume loading of the anaerobic pretreatment reactor is 5.0 - 6.6 kg COD / m 3 ·d, and the residence time is 10 - 12 h; the volume loading of the EIC anaerobic reactor is 2.2 - 3.0 kg COD / m 3 ·d, and the residence time is 3 - 4 d; the volume loading of the HEBR reactor is 0.4 - 0.6 kg COD / m 3 ·d, and the residence time is 3 - 4 d.

[0013] Optionally, the advanced treatment unit sequentially includes a CARB process and an ozone catalytic oxidation process according to the technological process, and uses the CARB process and the ozone catalytic oxidation process to treat refractory biochemical oxygen demand.

[0014] Optionally, the CARB process includes an activated carbon adsorption zone, a flocculation zone, a mixing reaction zone, and a sedimentation separation zone. The dosage of powdered activated carbon in the activated carbon adsorption zone is 700 mg / L to 800 mg / L, and the iodine value is 1000 mg / g to 1200 mg / g. Micro sand and inorganic flocculants are added in the flocculation zone to enhance the coagulation and precipitation of solid particles in water. In the mixing reaction zone, the wastewater is mixed with activated carbon, micro sand, and flocculants for reaction to strengthen flocculation and organic matter removal. The sludge and clarified effluent are discharged from the sedimentation separation zone, and the activated carbon and micro sand are separated and recovered. The residence time of the CARB process is 10 h to 12 h.

[0015] Optionally, the ozone dosage in the ozone catalytic oxidation process is 50 mg / L to 200 mg / L, the filling amount of the heterogeneous catalyst is 60% to 70%, and the residence time of the ozone catalytic oxidation process is 30 min to 1 h.

[0016] In the second aspect of the embodiments of the present application, a method for treating HPPO wastewater is provided. The treatment method is based on the HPPO wastewater treatment system in the first aspect to treat HPPO wastewater. The treatment method includes the following steps: introducing HP wastewater containing residual hydrogen peroxide into a flotation tank; introducing the effluent of the flotation tank into a homogenization and regulation tank to be mixed with PO wastewater stored in the homogenization and regulation tank to form HPPO wastewater; introducing the effluent of the homogenization and regulation tank into a Fenton catalytic oxidation reactor; introducing the effluent of the Fenton catalytic oxidation reactor into an anaerobic pretreatment reactor; introducing the effluent of the anaerobic pretreatment reactor into an EIC anaerobic reactor; introducing the effluent of the EIC anaerobic reactor into a HEBR biochemical tank; introducing the effluent of the HEBR biochemical tank into a CARB reactor; and introducing the effluent of the CARB reactor into an ozone catalytic oxidizer.

[0017] Therefore, the present application has the following beneficial effects:

[0018] In the embodiments of the present application, the pretreatment unit is used to remove oil and homogenize HP wastewater and PO wastewater respectively to obtain HPPO wastewater. The oxidation unit is used to remove part of the biochemical oxygen demand in HPPO wastewater by catalytic oxidation. Then, through the biochemical treatment unit, part of the biochemical oxygen demand in the effluent of the oxidation unit is removed by biochemical action. Finally, the advanced treatment unit is used to treat the refractory biochemical oxygen demand in the effluent of the biochemical treatment unit, improving the degradation efficiency of HPPO wastewater, making the effluent meet the standards, and the system operates flexibly with low cost and the treatment process is perfect. Thus, the problems in the related technology such as the complex catalyst production process, high cost, generation of a large amount of chemical sludge, and excessive iron ions and sulfate ions in the treated water, and low treatment efficiency for HPPO wastewater are solved.

[0019] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above-mentioned and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, where:

[0021] Figure 1 FIG. is a schematic structural diagram of an HPPO wastewater treatment system provided according to an embodiment of the present application;

[0022] Figure 2 FIG. is a process flow diagram of an HPPO wastewater treatment system provided according to an embodiment of the present application;

[0023] Figure 3 FIG. is a schematic flow diagram of an HPPO wastewater treatment method provided according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application.

[0025] The HPPO wastewater treatment system and method according to embodiments of the present application will be described below with reference to the accompanying drawings. In view of the problems in the related art mentioned in the above background technology, such as the complex catalyst production process, high cost, large amount of chemical sludge generated, and the excessive iron ions and sulfate ions in the treated water, and the low treatment efficiency of HPPO wastewater, the present application provides an HPPO wastewater treatment system. In this system, through a pretreatment unit, the HP wastewater and PO wastewater are respectively degreased and homogenized to obtain HPPO wastewater. An oxidation unit is used to remove part of the biochemical oxygen demand in the HPPO wastewater by catalytic oxidation. Then, through a biochemical treatment unit, part of the biochemical oxygen demand in the water discharged from the oxidation unit is removed by biochemical action. Finally, a deep treatment unit is used to treat the refractory biochemical oxygen demand in the water discharged from the biochemical treatment unit, improving the degradation efficiency of HPPO wastewater, achieving up-to-standard discharge, with flexible system operation and low cost, and a perfect treatment process. Thus, the problems in the related art, such as the complex catalyst production process, high cost, large amount of chemical sludge generated, and the excessive iron ions and sulfate ions in the treated water, and the low treatment efficiency of HPPO wastewater, are solved.

[0026] Specifically, Figure 1 FIG. is a schematic flow diagram of an HPPO wastewater treatment system provided according to an embodiment of the present application.

[0027] As Figure 1 shown, the HPPO wastewater treatment system includes: a pretreatment unit 101, an oxidation unit 102, a biochemical treatment unit 103, and an advanced treatment unit 104.

[0028] Among them, the pretreatment unit 101 removes oil and homogenizes the HP wastewater and the PO wastewater respectively to obtain HPPO wastewater; the oxidation unit 102 uses catalytic oxidation to remove part of the biochemical oxygen demand in the HPPO wastewater; the biochemical treatment unit 103 uses biochemical action to remove part of the biochemical oxygen demand in the effluent of the oxidation unit, and the biochemical oxygen demand removed by the biochemical treatment unit 103 is greater than that removed by the oxidation unit 102; the advanced treatment unit 104 treats the refractory biochemical oxygen demand in the effluent of the biochemical treatment unit 103.

[0029] It can be understood that in the embodiment of the present application, the wastewater is first subjected to air flotation for oil removal and homogenization adjustment in the pretreatment unit 101, so that the HP wastewater and the PO wastewater become uniform HPPO wastewater. Then, the wastewater flows into the oxidation unit 102, and part of the biochemical oxygen demand in the HPPO wastewater is removed by catalytic oxidation. Subsequently, the wastewater enters the biochemical treatment unit 103, and most of the biochemical oxygen demand is removed by biochemical action. The wastewater will pass through the advanced treatment unit 104 to specifically treat the refractory biochemical oxygen demand, so as to ensure that the quality of the final discharged water meets strict environmental standards.

[0030] In the embodiment of the present application, the biochemical oxygen demand removed by the oxidation unit 102 accounts for 14% - 17% of the total removed biochemical oxygen demand, the biochemical oxygen demand removed by the biochemical treatment unit 103 accounts for 82% - 84% of the total removed biochemical oxygen demand, and the biochemical oxygen demand removed by the advanced treatment unit 104 accounts for 1.5% - 2% of the total removed biochemical oxygen demand.

[0031] In the embodiment of the present application, the pretreatment unit 101 includes an air flotation tank and a homogenization and adjustment tank using the air flotation oil removal technology. Among them, the homogenization and adjustment tank is located downstream of the air flotation tank. The homogenization and adjustment tank stores the PO wastewater to be treated. The HP wastewater removes the floating oil through the air flotation tank and enters the homogenization and adjustment tank to be homogenized and mixed with the PO wastewater to be treated to obtain HPPO wastewater.

[0032] Among them, the air flotation oil removal technology is a wastewater treatment method. By injecting tiny bubbles into the wastewater, the oil and light suspended solids in the wastewater adhere to the bubbles and float to the water surface, thereby realizing the separation of oil and water.

[0033] It is understandable that in the pretreatment stage of the wastewater treatment process of this application embodiment, first, the oil flotation technology in the air flotation tank is used to remove the floating oil in the HP wastewater. The HP wastewater from which the floating oil has been removed flows into the homogeneous regulation tank located downstream of the air flotation tank, where it is mixed with the PO wastewater stored in the tank to form a uniform HPPO wastewater.

[0034] In the embodiment of this application, the oxidation unit 102 is provided with a Fenton catalytic oxidation reactor, and the Fenton catalytic oxidation reactor is used to moderately remove the biochemical oxygen demand in the HPPO wastewater by Fenton reaction.

[0035] Among them, the Fenton catalytic oxidation reactor is a device that uses the Fenton reaction to degrade harmful organic substances in wastewater. The Fenton reaction is an advanced oxidation process that generates strongly oxidizing hydroxyl radicals (·OH) through the reaction between ferrous ions (Fe 2+ ) and hydrogen peroxide (H2O2), thereby efficiently decomposing hardly biodegradable organic pollutants.

[0036] It is understandable that in the oxidation unit 102 of the embodiment of this application, a Fenton catalytic oxidation reactor is provided. This reactor uses the Fenton reaction to treat the HPPO wastewater from the pretreatment unit 101 and remove the biochemical oxygen demand in the HPPO wastewater.

[0037] In the embodiment of this application, the Fenton catalytic oxidizer includes an acid adjustment area, a catalytic oxidation area, a neutralization area, and a flocculation precipitation area. Among them, the acid adjustment area adjusts the pH to 3 - 4, the oxidant dosage in the catalytic oxidation area is 3000 - 3200 mg / L, the catalyst FeSO4 dosage is 1300 - 1400 mg / L, the neutralization area adjusts the pH to 9 - 10, and the residence time is 2 h - 4 h.

[0038] Among them, the residence time refers to the actual residence time length of the wastewater in the system unit. During this time, the wastewater is fully contacted with chemical agents in the unit and reacts.

[0039] It is understandable that the Fenton catalytic oxidizer of the embodiment of this application includes an acid adjustment area, a catalytic oxidation area, a neutralization area, and a flocculation precipitation area. The pH value of the HPPO wastewater can be reduced to 3 - 4 through the acid adjustment area. Then, an appropriate amount of oxidant and FeSO4 are added in the catalytic oxidation area to initiate the Fenton reaction. After the reaction is completed, the pH value is raised to 9 - 10 in the neutralization area. The whole process takes 2 to 4 hours to ensure complete reaction and effective precipitation.

[0040] In the embodiment of this application, the biochemical treatment unit 103 sequentially includes, according to the process flow: an anaerobic pretreatment reactor, an EIC anaerobic reactor, and a HEBR biochemical pool. Among them, the volume load of the anaerobic pretreatment reactor is 5.0 - 6.6 kg COD / m 3·d, with a residence time of 10 - 12 h; the volumetric loading of the EIC anaerobic reactor is 2.2 - 3.0 kg COD / m 3 ·d, with a residence time of 3 - 4 d; the volumetric loading of the HEBR reactor is 0.4 - 0.6 kg COD / m 3 ·d, with a residence time of 3 - 4 d.

[0041] It can be understood that the biochemical treatment unit 103 of this application embodiment includes an anaerobic pretreatment reactor, an EIC anaerobic reactor, and a HEBR biochemical pool. The HPPO wastewater first flows into the anaerobic pretreatment reactor, where the short-chain alcohol substances in the wastewater are initially decomposed into simpler organic acids. The volumetric loading of this process is 5.0 - 6.6 kg COD / m 3 ·d, and the wastewater stays here for 10 to 12 hours. Subsequently, the wastewater enters the EIC anaerobic reactor. The volumetric loading of this stage is 2.2 - 3.0 kg COD / m 3 ·d, and the residence time of the wastewater is 3 to 4 days. Finally, the wastewater after the first two steps of treatment enters the HEBR biochemical pool to further degrade the remaining small-molecule organic substances and simultaneously achieve nitrogen and phosphorus removal. The volumetric loading of the HEBR reactor is 0.4 - 0.6 kgCOD / m 3 ·d, and the wastewater stays here for 3 to 4 days.

[0042] In the embodiment of this application, the advanced treatment unit 104 sequentially includes, according to the process flow: the CARB process and the ozone catalytic oxidation process, and uses the CARB process and the ozone catalytic oxidation process to treat the refractory biochemical oxygen demand.

[0043] Among them, the CARB process will be described in detail below and will not be elaborated here; the ozone catalytic oxidation process is an advanced oxidation technology that uses the strong oxidation ability of ozone (O3) and combines with a heterogeneous catalyst to accelerate and enhance the oxidation and decomposition of refractory organic substances in the wastewater, and will be described in detail below and will not be elaborated here.

[0044] It can be understood that the advanced treatment unit 104 of the embodiment of this application uses the CARB process and the ozone catalytic oxidation process to remove the refractory organic substances remaining after biochemical treatment and treat the refractory biochemical oxygen demand.

[0045] In the embodiment of the present application, the CARB process includes an activated carbon adsorption zone, a flocculation zone, a mixing reaction zone, and a sedimentation separation zone. The dosage of powdered activated carbon in the activated carbon adsorption zone is 700 mg / L to 800 mg / L, and the iodine value is 1000 mg / g to 1200 mg / g. Micro sand and inorganic flocculants are added in the flocculation zone to enhance the coagulation and precipitation of solid particles in water. In the mixing reaction zone, the wastewater is mixed and reacted with activated carbon, micro sand, and flocculants to strengthen the flocculation and organic matter removal effects. In the sedimentation separation zone, sludge and clarified effluent are discharged, and the activated carbon and micro sand are separated and recovered. The residence time of the CARB process is 10 h to 12 h.

[0046] It can be understood that in the CARB process of the embodiment of the present application, the HPPO wastewater is first input into the activated carbon adsorption zone, where the dosage of powdered activated carbon is 700 mg / L to 800 mg / L and the iodine value is 1000 mg / g to 1200 mg / g. Then, the wastewater enters the flocculation zone, where micro sand and inorganic flocculants are added to promote the coagulation of fine particles in water, making them easier to precipitate. Subsequently, the wastewater enters the mixing reaction zone, where the wastewater is fully mixed with the previously added activated carbon, micro sand, and flocculants, enhancing the flocculation effect and further removing organic matter. Finally, the wastewater reaches the sedimentation separation zone, where the formed larger particles settle to the bottom and are discharged as sludge, while the treated water continues to flow forward.

[0047] In the embodiment of the present application, the ozone dosage in the ozone catalytic oxidation process is 50 mg / L to 200 mg / L, the filling amount of the heterogeneous catalyst is 60% to 70%, and the residence time of the ozone catalytic oxidation process is 30 min to 1 h.

[0048] It can be understood that in the ozone catalytic oxidation process of the embodiment of the present application, the wastewater enters the ozone catalytic oxidation unit, where ozone gas is first injected into the wastewater at a rate of 50 to 200 mg / L. At the same time, the reactor is pre-filled with a heterogeneous catalyst accounting for 60% to 70% of the total volume. These catalysts can significantly improve the utilization rate of ozone and the reaction rate, thereby deeply oxidizing and degrading the refractory biodegradable organic matter in the wastewater. The wastewater stays here for about 30 minutes to 1 hour to ensure that there is enough time for ozone to interact with organic pollutants, ultimately achieving efficient removal of residual refractory organic substances and ensuring that the effluent quality meets strict discharge standards.

[0049] The HPPO wastewater treatment system proposed according to the embodiments of the present application uses a pretreatment unit to remove oil and homogenize HP wastewater and PO wastewater respectively to obtain HPPO wastewater, and uses an oxidation unit to remove part of the biochemical oxygen demand in the HPPO wastewater through catalytic oxidation. Then, through a biochemical treatment unit, part of the biochemical oxygen demand in the effluent of the oxidation unit is removed by biochemical action. Finally, a advanced treatment unit is used to treat the refractory biochemical oxygen demand in the effluent of the biochemical treatment unit, improving the degradation efficiency of HPPO wastewater, making the effluent meet the standards, the system operates flexibly with low cost, and the treatment process is perfect.

[0050] The HPPO wastewater treatment system will be further described below through a specific embodiment.

[0051] As Figure 2 shown, a HPPO wastewater treatment system provided in this embodiment includes, in sequence according to the technological process:

[0052] A pretreatment unit; an advanced oxidation unit downstream of the pretreatment unit and connected to the pretreatment unit; a biochemical treatment unit downstream of the advanced oxidation unit; and an advanced treatment unit located downstream of the biochemical treatment unit.

[0053] The pretreatment unit respectively performs oil removal and homogenization pretreatment on HP wastewater and PO wastewater;

[0054] The advanced oxidation unit receives the effluent of the pretreatment unit and performs moderate Fenton to remove part of its biochemical oxygen demand COD, accounting for 14% - 17% of the system's COD removal rate;

[0055] The biochemical treatment unit receives the effluent of the advanced oxidation unit and removes most of the biochemical oxygen demand COD, accounting for 82% - 84% of the system's COD removal rate;

[0056] The advanced treatment unit receives the effluent of the biochemical treatment unit and removes the biochemical oxygen demand COD of the residual refractory organic matter, accounting for 1.5% - 2% of the system's COD removal rate.

[0057] Specifically, the pretreatment unit of the wastewater system in this embodiment is a flotation tank 1 based on the flotation oil removal technology, and also includes a homogenization and regulation tank 2. The homogenization and regulation tank 2 is located downstream of the flotation tank 1, and the homogenization and regulation tank 2 stores the PO wastewater to be treated; the HP wastewater removes floating oil through the flotation tank 1 and enters the homogenization and regulation tank 2 to be homogenized and mixed with the PO wastewater to be treated, and they are collectively called HPPO wastewater.

[0058] The advanced oxidation unit is equipped with a Fenton catalytic oxidation reactor 3; the Fenton catalytic oxidizer 3 includes an acid adjustment area, a catalytic oxidation area, a neutralization area, and a flocculation and precipitation area. The pH in the acid adjustment area is adjusted to 3 - 4, the dosage of the oxidant H2O2 in the catalytic oxidation area is 3000 - 3200 mg / L, the dosage of the catalyst FeSO4 is 1300 - 1400 mg / L, the pH in the neutralization area is adjusted to 9 - 10, and the effective residence time is 2 h - 4 h.

[0059] The biochemical treatment unit successively includes, according to the technological process: an anaerobic pretreatment reactor 4, an EIC anaerobic reactor 5, and a HEBR biochemical tank 6; the volume load of the anaerobic pretreatment reactor is 5.2 - 6.6 kg COD / m 3 ·d, and the effective residence time is 10 - 12 h; the volume load of the EIC anaerobic reactor is 2.2 - 3.0 kg COD / m 3 ·d, and the effective residence time is 3 - 4 d; the volume load of the HEBR reactor is 0.4 - 0.6 kg COD / m 3 ·d, and the effective residence time is 3 - 4 d.

[0060] The advanced treatment unit successively includes, according to the technological process: a CARB process and an ozone catalytic oxidation process; the CARB process includes an activated carbon adsorption area, a flocculation area, a mixing reaction area, and a precipitation separation area. The dosage of powdered activated carbon in the activated carbon adsorption area is 700 mg / L - 800 mg / L, the iodine value is 1000 mg / g - 1200 mg / g. Micro - sand and inorganic flocculants are added in the flocculation area to enhance the coagulation and precipitation of solid particles in water. In the mixing reaction area, the wastewater is mixed with activated carbon, micro - sand, and flocculants for reaction to strengthen flocculation and the removal of organic matter. In the precipitation separation area, sludge and effluent are discharged, and activated carbon and micro - sand are separated and recovered. The effective residence time of the process is 10 h - 12 h; the ozone dosage in the ozone catalytic oxidation process is 50 mg / L - 200 mg / L, the filling amount of the heterogeneous catalyst is 60% - 70%, and the effective residence time is 30 min - 1 h.

[0061] The treatment principle of the treatment system disclosed in this embodiment is: the pretreatment unit uses air - flotation oil removal technology to remove floating oil in the HP wastewater. On the one hand, it preferentially removes the recalcitrant heavy aromatic ester and ketone organic matters adsorbed in the oil phase in the HP wastewater. On the other hand, it avoids the interference of oil substances on the subsequent Fenton advanced oxidation reactants and the solubility of Fe 2+ and H2O2, thus changing the reaction efficiency. The advanced oxidation unit adopts a moderate Fenton process using the catalyst ferrous ion (Fe 2+) The reaction with the oxidant hydrogen peroxide (H2O2) generates hydroxyl radicals (·OH) to effectively degrade organic pollutants, improve the biodegradability of wastewater, and at the same time greatly reduce the consumption of catalysts and oxidants. The biochemical treatment unit uses anaerobic pretreatment to degrade short-chain alcohols and decompose them into organic acids. EIC anaerobically degrades long-chain alcohols and converts macromolecular organic matter into small-molecular organic matter. The HEBR process further degrades small-molecular organic matter and removes nitrogen and phosphorus in a low-oxygen environment. Subsequently, the effluent enters the advanced treatment unit.

[0062] In the advanced treatment unit, the CARB process effectively removes complex pollutants, especially refractory organic pollutants, in the secondary effluent through the adsorption and flocculation effects of activated carbon, microsand, and flocculants working together. Through multi-level treatment, the advanced treatment efficiency is improved to ensure the reliability and stability of the effluent quality. The CARB effluent enters the ozone catalytic oxidation process. Using the strong oxidizing property of ozone and the catalyst to enhance the oxidation efficiency, refractory organic pollutants are further degraded, making the COD index of the system effluent better than the first-class standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18978-2002).

[0063] A factory producing propylene oxide by the HPPO process has a production process line that produces about 10% of HP wastewater and about 90% of PO wastewater. The water quality indicators are as shown in Table 1 below. Among them, Table 1 is the water quality indicator table:

[0064] Table 1

[0065]

[0066] The treatment method of this embodiment includes the following steps:

[0067] The HP wastewater enters the air flotation tank 1. After oil removal, the effluent of the air flotation tank 1 enters the homogeneous regulation tank 2 and is homogeneously mixed with the PO water at a ratio of 1:9 to form HPPO wastewater, which then enters the Fenton catalytic oxidation reactor. The HPPO wastewater is alkaline, and the COD is 15000 mg / L - 16000 mg / L.

[0068] H2SO4 is added to the acid adjustment area of the Fenton catalytic oxidation reactor to adjust the pH to 3. The effluent of the adjustment area enters the catalytic oxidation area. A 3000 mg / L H2O2 solution and a 1300 mg / L FeSO4 solution are added to the catalytic oxidation area and react fully for two hours. The effluent of the catalytic oxidation area enters the neutralization area, and NaOH solution is added to the neutralization area to adjust the pH to 10.

[0069] The neutralized effluent enters the flocculation and sedimentation area, and the coagulant aid PAM and the flocculant PAC are added to the flocculation area for flocculation and sedimentation. The effluent of the flocculation and sedimentation enters the anaerobic pretreatment reactor, and the treatment load of the anaerobic pretreatment reactor is 5.3 kg COD / m 3·d, the effective residence time is 12 h. The hydrolytic acidification bacteria in the reactor are the dominant strains, which have a good degradation effect on short-chain alcohols, and the pH of the effluent is about 5.6.

[0070] The effluent from the anaerobic pretreatment reactor enters the EIC anaerobic reactor. The treatment load of the EIC anaerobic reactor is 2.3 kgCOD / m 3 ·d, the effective residence time is 90 h. The methanogenic bacteria in the reactor are the dominant strains, which have a good degradation effect on long-chain alcohols, and the pH of the effluent is about 7.1. The effluent from the EIC anaerobic reactor enters the HEBR reactor. The treatment load of the HEBR reactor is 0.6 kgCOD / m 3 ·d, the effective residence time is 90 h. The aerobic microorganisms in the reactor continue to degrade small-molecule organic matter and remove nitrogen and phosphorus under low-oxygen conditions.

[0071] The effluent from the HEBR reactor enters the CARB reactor. First, it enters the activated carbon adsorption zone and is fully mixed with the powdered activated carbon in the adsorption zone to adsorb and remove the refractory organic matter in the influent. The effluent from the adsorption zone enters the flocculation zone. The use of microsand and inorganic flocculants makes the solid particle suspensions in the effluent coagulate into larger precipitates and settle quickly. The effluent from the flocculation zone enters the mixing reaction zone, that is, the effluent is mixed and reacted with microsand, activated carbon, and flocculants to enhance the removal of refractory organic matter. Finally, the effluent enters the sedimentation and separation zone. The flocs sink to the bottom and are discharged through the bottom sludge discharge facility. The microsand and activated carbon are separated by a hydrocyclone. At the same time, the saturated activated carbon is discharged from the system and returned to the adsorption zone after regeneration. The effective residence time of the water flow in the CARB reactor is 10 h.

[0072] The effluent from the CARB reactor enters the ozone catalytic oxidation reactor. The ozone dosage is 50 mg / L, the filling amount of the heterogeneous catalyst is 70%, and the residence time is 1 h. The COD index of the system effluent is better than the first-class standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18978 2002). The COD indexes of the effluents from each unit and the system effluent after the implementation of this example are shown in Table 2. Among them, Table 2 is the table of COD indexes of the effluents from each unit and the system effluent.

[0073] Table 2

[0074]

[0075] The following describes a comparative example 1. Comparative example 1 compares the difference in the removal rate of refractory COD in the biochemical effluent between the conventional activated carbon adsorption process and the CARB process in the advanced treatment unit, and the removal rate of using the ozone catalytic oxidation process alone as the advanced treatment unit to degrade refractory COD in the biochemical effluent, so as to prove the high efficiency of the CARB process and the ozone catalytic maintenance process in synergistic advanced treatment.

[0076] The treatment method from the pretreatment unit to the advanced oxidation unit to the biochemical treatment unit in Comparative Example 1 is the same as that in the above embodiment. In the advanced treatment unit, the traditional activated carbon adsorption process is used to replace the CARB process respectively, that is, after the HEBR effluent enters the activated carbon adsorption area, the effluent directly enters the ozone catalytic oxidation process; and the separate ozone catalytic oxidation process is used as the advanced treatment, that is, the HEBR effluent directly enters the ozone catalytic oxidation process. The COD index of the effluent from the advanced treatment unit after the implementation of Comparative Example 1 is shown in Table 3. Among them, Table 3 is the COD index table of the effluent from the advanced treatment unit.

[0077] Table 3

[0078]

[0079] The following describes a Comparative Example 2. Comparative Example 2 compares the influence of the presence or absence of the advanced oxidation unit, especially the moderate Fenton advanced oxidation adopted by the advanced oxidation unit, on the operation of the subsequent biochemical system, so as to prove the importance of moderate Fenton for the balanced utilization of the system carbon source.

[0080] Except for the absence of the advanced oxidation unit, the other treatment steps and processes in Comparative Example 2 are the same as those in the above embodiment, that is, the biochemical treatment unit directly receives the effluent from the pretreatment unit. The COD removal rate index of the biological treatment unit after the implementation of Comparative Example 2 is shown in Table 4. Among them, Table 4 is the COD removal rate index table of the biological treatment unit.

[0081] Table 4

[0082]

[0083]

[0084] The results show that after being treated by the moderate Fenton advanced oxidation unit, the COD (chemical oxygen demand) removal rate of the biological treatment unit for the wastewater is increased by about 20% compared with the overall biological treatment alone, indicating that the moderate Fenton advanced oxidation improves the carbon source utilization of the subsequent biological treatment.

[0085] For the water quality before and after the moderate Fenton treatment in the above embodiment, an organic matter component analysis is carried out. The test method is qualitative by GCMS area normalization method. The specific results are shown in Table 5. Table 5 is the qualitative result table by GCMS area normalization method.

[0086] Table 5

[0087]

[0088]

[0089] Combined with the detection results, it can be seen that after moderate Fenton advanced oxidation, the generated products include trimethyl-propylsilane and methyl 2-hydroxyisobutyrate, which have relatively simple structures and are more easily degraded by subsequent biochemical processes; propylene glycol ethyl ether and 2,3-dimethoxy-2-methylbutane have relatively high polarity and water solubility, are easily interacted with water, and improve their bioavailability; the relative content of the hardly biodegradable long-chain alcohol 4,7,10-trimethyl-2,5,8,11-tetraoxatetradecan-13-ol is greatly reduced. Based on the COD removal rate data of the effluent from the integrated biochemical unit and the analysis results of the organic matters in the water quality before and after moderate Fenton, it can be known that moderate Fenton advanced oxidation improves the utilization of carbon sources in subsequent biological treatment and thus enhances the carbon source utilization efficiency of the overall treatment process.

[0090] Next, the HPPO wastewater treatment method proposed according to the embodiments of the present application will be described with reference to the accompanying drawings.

[0091] Figure 3 It is a schematic flow chart of the HPPO wastewater treatment method according to the embodiments of the present application.

[0092] As Figure 3 shown, the HPPO wastewater treatment method includes the following steps:

[0093] In step S201, the HP wastewater containing residual hydrogen peroxide enters the air flotation tank.

[0094] It can be understood that in the embodiments of the present application, the HP wastewater containing residual hydrogen peroxide is first introduced into the air flotation tank. In the air flotation tank, by injecting minute bubbles into the wastewater, the grease and suspended solids in the wastewater adhere to the bubbles and float to the water surface to form scum, and these scum are removed.

[0095] In step S202, the effluent from the air flotation tank enters the homogeneous regulation tank and is mixed with the PO wastewater stored in the homogeneous regulation tank to form HPPO wastewater.

[0096] It can be understood that in the embodiments of the present application, the effluent from the air flotation tank then flows into the homogeneous regulation tank, where it is uniformly mixed with the PO wastewater pre-stored in this tank in a certain proportion to form HPPO wastewater.

[0097] In step S203, the effluent from the homogeneous regulation tank enters the Fenton catalytic oxidation reactor.

[0098] It can be understood that in the embodiments of the present application, the HPPO wastewater is then sent into the Fenton catalytic oxidation reactor, the pH value is adjusted to 3-4, and then an appropriate amount of oxidant and ferrous sulfate (FeSO4) are added as a catalyst, which can effectively break the structure of hardly degradable organic matters. After the reaction is completed, the pH value is adjusted back to 9-10 again to facilitate precipitation and subsequent treatment. The effective residence time of the entire Fenton reaction is 2 hours to 4 hours.

[0099] In step S204, the effluent from the Fenton catalytic oxidation reactor enters the anaerobic pretreatment reactor.

[0100] It can be understood that in the embodiment of the present application, the wastewater after Fenton catalytic oxidation treatment flows into the anaerobic pretreatment reactor for anaerobic treatment to initially decompose some easily degradable organic matters in the wastewater.

[0101] In step S205, the effluent from the anaerobic pretreatment reactor enters the EIC anaerobic reactor.

[0102] It can be understood that in the embodiment of the present application, the effluent from the anaerobic pretreatment reactor continues to flow into the EIC anaerobic reactor, and the organic matters in the wastewater are further degraded into smaller compounds.

[0103] In step S206, the effluent from the EIC anaerobic reactor enters the HEBR biochemical pool.

[0104] It can be understood that in the embodiment of the present application, the wastewater flowing out from the EIC anaerobic reactor then enters the HEBR biochemical pool, where not only the complete degradation of the remaining small-molecule organic matters is completed, but also a good denitrification and phosphorus removal effect is achieved, greatly reducing the content of nutrients in the wastewater.

[0105] In step S207, the effluent from the HEBR biochemical pool enters the CARB reactor.

[0106] It can be understood that in the embodiment of the present application, after the above biochemical treatment is completed, the wastewater enters the CARB reactor for advanced treatment. The CARB process includes four regions: activated carbon adsorption, flocculation, mixing reaction, and precipitation separation, which strengthens the removal of organic matters.

[0107] In step S208, the effluent from the CARB reactor enters the ozone catalytic oxidizer.

[0108] It can be understood that in the embodiment of the present application, the effluent from the CARB reactor is input into the ozone catalytic oxidizer. Ozone is introduced into the wastewater at a set ratio (50 - 200 mg / L), and a heterogeneous catalyst with a filling rate of 60% to 70% is used to accelerate and enhance the oxidation of ozone to refractory organic matters. The wastewater stays here for about 30 minutes to 1 hour to ensure that there is enough time for ozone to interact with organic pollutants, and finally achieve efficient removal of residual refractory organic substances to ensure that the effluent quality meets strict discharge standards.

[0109] It should be noted that the foregoing explanation of the embodiment of the HPPO wastewater treatment method also applies to the HPPO wastewater treatment system of this embodiment, and will not be elaborated here.

[0110] According to the HPPO wastewater treatment method proposed in the embodiments of the present application, through the pretreatment unit, the HP wastewater and the PO wastewater are respectively degreased and homogenized to obtain HPPO wastewater. The oxidation unit is used to remove part of the biochemical oxygen demand in the HPPO wastewater by catalytic oxidation. Then, through the biochemical treatment unit, the biochemical action is used to remove part of the biochemical oxygen demand in the effluent of the oxidation unit. Finally, the advanced treatment unit is used to treat the refractory biochemical oxygen demand in the effluent of the biochemical treatment unit, improving the degradation efficiency of the HPPO wastewater, making the effluent meet the standards, the system operation flexible and the cost low, and the treatment process perfect.

[0111] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0112] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0113] Any process or method description shown in the flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or N executable instructions for implementing a customized logic function or process, and the scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a substantially simultaneous manner or in the reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art of the embodiments of the present application.

[0114] It should be understood that various parts of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, the steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays, field programmable gate arrays, etc.

[0115] Those of ordinary skill in the art can understand that all or part of the steps carried by the methods in the above embodiments can be completed by instructing relevant hardware through a program. The above program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0116] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. An HPPO wastewater treatment system, characterized in that, Comprising: A pretreatment unit that removes oil and homogenizes HP wastewater and PO wastewater respectively to obtain HPPO wastewater; An oxidation unit that uses catalytic oxidation to remove part of the biochemical oxygen demand in the HPPO wastewater; A biochemical treatment unit that uses biochemical action to remove part of the biochemical oxygen demand in the effluent from the oxidation unit, wherein the biochemical oxygen demand removed by the biochemical treatment unit is greater than that removed by the oxidation unit; An advanced treatment unit that treats the refractory biochemical oxygen demand in the effluent from the biochemical treatment unit.

2. The HPPO wastewater treatment system according to claim 1, wherein The biochemical oxygen demand removed by the oxidation unit accounts for 14% - 17% of the total removed biochemical oxygen demand, the biochemical oxygen demand removed by the biochemical treatment unit accounts for 82% - 84% of the total removed biochemical oxygen demand, and the biochemical oxygen demand removed by the advanced treatment unit accounts for 1.5% - 2% of the total removed biochemical oxygen demand.

3. The HPPO wastewater treatment system according to claim 1, wherein The pretreatment unit includes a flotation tank using flotation oil removal technology and a homogenization and regulation tank. Among them, the homogenization and regulation tank is located downstream of the flotation tank. The homogenization and regulation tank stores the PO wastewater to be treated. The HP wastewater removes floating oil through the flotation tank and enters the homogenization and regulation tank to be homogenized and mixed with the PO wastewater to be treated to obtain HPPO wastewater.

4. The HPPO wastewater treatment system according to claim 1, characterized in that, The oxidation unit is provided with a Fenton catalytic oxidation reactor, and the Fenton catalytic oxidation reactor is used for moderate Fenton to remove the biochemical oxygen demand in the HPPO wastewater.

5. The HPPO wastewater treatment system according to claim 4, wherein, The Fenton catalytic oxidizer includes an acid adjustment area, a catalytic oxidation area, a neutralization area, and a flocculation and precipitation area. Among them, the pH in the acid adjustment area is adjusted to 3 - 4, the oxidant dosage in the catalytic oxidation area is 3000 - 3200 mg / L, the catalyst FeSO4 dosage is 1300 - 1400 mg / L, the pH in the neutralization area is adjusted to 9 - 10, and the residence time is 2 h - 4 h.

6. The HPPO wastewater treatment system according to claim 1, wherein, The biochemical treatment unit sequentially includes, according to the process flow: an anaerobic pretreatment reactor, an EIC anaerobic reactor, and a HEBR biochemical pool. Among them, The volume loading of the anaerobic pretreatment reactor is 5.0 - 6.6 kg COD / m 3 ·d, and the residence time is 10 - 12 h; The volumetric loading rate of the EIC anaerobic reactor is 2.2 - 3.0 kg COD / m 3 ·d, and the retention time is 3 - 4 d; The volumetric loading of the HEBR reactor is 0.4 - 0.6 kg COD / m 3 ·d, and the residence time is 3 - 4 d.

7. The HPPO wastewater treatment system according to claim 1, wherein, The advanced treatment unit sequentially includes, according to the process flow: a CARB process and an ozone catalytic oxidation process, and the CARB process and the ozone catalytic oxidation process are used to treat the refractory biochemical oxygen demand.

8. The HPPO wastewater treatment system according to claim 7, characterized in that, The CARB process includes an activated carbon adsorption area, a flocculation area, a mixing reaction area, and a precipitation and separation area. The powdered activated carbon dosage in the activated carbon adsorption area is 700 mg / L - 800 mg / L, and the iodine value is 1000 mg / g - 1200 mg / g. Micro - sand and inorganic flocculants are added in the flocculation area to enhance the coagulation and precipitation of solid particles in water. In the mixing reaction area, the wastewater is mixed and reacted with activated carbon, micro - sand, and flocculants to strengthen the flocculation and organic matter removal effects. The precipitation and separation area discharges sludge and clarified effluent, and separates and recovers the activated carbon and the micro - sand. The residence time of the CARB process is 10 h - 12 h.

9. The HPPO wastewater treatment system according to claim 7, wherein The ozone dosage in the ozone catalytic oxidation process is 50 mg / L - 200 mg / L, the filling amount of the heterogeneous catalyst is 60% - 70%, and the residence time of the ozone catalytic oxidation process is 30 min - 1 h.

10. A method for treating HPPO wastewater, characterized in that, The treatment method is based on the HPPO wastewater treatment system described in any one of claims 1-9 for treating HPPO wastewater, and the treatment method includes the following steps: Let the HP wastewater containing residual hydrogen peroxide enter the air flotation tank; Let the effluent from the air flotation tank enter the homogenization and regulation tank and be mixed with the PO wastewater stored in the homogenization and regulation tank to form HPPO wastewater; Let the effluent from the homogenization and regulation tank enter the Fenton catalytic oxidation reactor; Let the effluent from the Fenton catalytic oxidation reactor enter the anaerobic pretreatment reactor; Let the effluent from the anaerobic pretreatment reactor enter the EIC anaerobic reactor; Let the effluent from the EIC anaerobic reactor enter the HEBR biochemical pool; Let the effluent from the HEBR biochemical pool enter the CARB reactor; Let the effluent from the CARB reactor enter the ozone catalytic oxidizer.

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