Integrated reverse osmosis treatment system for high organic wastewater

Abstract

The present application belongs to the technical field of sewage treatment, and particularly relates to an integrated reverse osmosis treatment system for high-organic wastewater. The organic wastewater is subjected to gravity sedimentation treatment to obtain first-stage treated wastewater; the first-stage treated wastewater is subjected to magnetic flocculation treatment to obtain secondary treated wastewater and flocculation wastewater; the secondary treated wastewater is subjected to microbial electrolysis treatment to obtain carbon dioxide and tertiary treated wastewater; ozone is introduced into the tertiary treated wastewater, and the tertiary treated wastewater is subjected to ozone catalytic oxidation treatment under the catalysis of a catalyst to degrade the organic pollutants in the tertiary treated wastewater, thereby obtaining fourth-stage treated wastewater. The present application can significantly reduce the concentrations of organic pollutants and biological pollutants in the high-organic wastewater, thereby effectively reducing the adhesion of pollutants on the surface of the reverse osmosis membrane used in subsequent reverse osmosis treatment, accurately reducing the risk of organic and biological blockage of raw water, and significantly improving the operation stability and water treatment efficiency of the high-recovery-rate reverse osmosis system.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to an integrated reverse osmosis treatment system for high-organic wastewater. Background Technology

[0002] Reverse osmosis membrane technology plays a crucial role in treating wastewater with high organic content, such as recalcitrant wastewater and industrial wastewater, due to its efficient removal of salt, organic matter, and pathogenic microorganisms from water. However, biofouling is a particularly challenging problem when treating such high-organic-content water sources. Biofouling refers to the formation of a biofilm by microorganisms on the membrane surface. Over time, this biofilm accumulates, leading to a sharp decrease in membrane flux and a significant increase in transmembrane pressure, severely restricting system operating efficiency. This type of fouling not only increases cleaning frequency and energy consumption but also shortens membrane lifespan, significantly increasing operating costs. This contradiction is even more pronounced in high-recovery-rate reverse osmosis systems—while high recovery rates improve water resource utilization, they exacerbate the concentration effect of organic matter and microorganisms, accelerating biofouling formation.

[0003] It is noteworthy that traditional pretreatment technologies, when applied to reverse osmosis pretreatment of organic wastewater with high organic content, struggle to effectively suppress biofouling and reduce organic and biological fouling of the reverse osmosis membrane. Faced with the complex demands of treating recalcitrant wastewater and industrial park wastewater, the market requires novel pretreatment technologies that combine high treatment capacity with small footprint and integrated advantages. These technologies aim to overcome traditional technological bottlenecks, better address the biofouling problem in treating water sources with high organic content, and contribute to achieving near-zero emissions goals. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated reverse osmosis treatment system for high organic wastewater. The reverse osmosis pretreatment method provided by this invention can effectively reduce the adhesion of pollutants on the surface of the reverse osmosis membrane, reduce the risk of organic and biological fouling of the reverse osmosis membrane, significantly improve the operational stability and water treatment efficiency of the osmosis system, reduce energy consumption, reduce maintenance frequency, and extend the service life of the membrane module.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a reverse osmosis pretreatment method for organic wastewater, comprising the following steps:

[0007] (1) The organic wastewater is subjected to gravity sedimentation treatment to obtain primary treated wastewater;

[0008] (2) The primary wastewater is subjected to magnetic flocculation treatment to obtain secondary wastewater and flocculated wastewater. The magnetic flocculation treatment includes adding coagulant, magnetic mixing agent and coagulant aid to the primary wastewater in sequence, and then performing flocculation and sedimentation.

[0009] (3) The secondary treated wastewater is subjected to microbial electrolysis to obtain carbon dioxide and tertiary treated wastewater;

[0010] (4) Ozone is introduced into the tertiary wastewater and ozone catalytic oxidation is carried out under the catalytic conditions of the catalyst to degrade the organic pollutants in the tertiary wastewater and obtain quaternary wastewater.

[0011] Preferably, the coagulant includes polyaluminum chloride (PAC), and the mass ratio of the coagulant to the volume of the organic wastewater is (5-50) mg: 1 L;

[0012] The magnetic mixer comprises iron(III) oxide, and the mass ratio of the magnetic mixer to the volume of the organic wastewater is (10-100) mg: 1 L;

[0013] The coagulant aid includes anionic polyacrylamide and / or nonionic polyacrylamide, and the mass ratio of the coagulant aid to the volume of the organic wastewater is (1-10) mg: 1 L.

[0014] The pH value of the magnetic flocculation treatment is 6-7, and the pH value is adjusted by carbon dioxide.

[0015] Preferably, after obtaining the flocculated wastewater, the method further includes: recovering the flocculated wastewater using a magnetic mixer to obtain a recovered magnetic mixer and non-magnetic substances, wherein the recovered magnetic mixer is reused in step (2).

[0016] Preferably, after obtaining carbon dioxide through microbial electrolysis, the method further includes using the carbon dioxide obtained through microbial electrolysis for pH adjustment in magnetic flocculation treatment.

[0017] Preferably, the microbial electrolysis treatment is carried out under anaerobic conditions of an anode and an oxygen-supplying cathode. The microbial electrolysis treatment is carried out in a microbial electrolysis cell, which includes an anode chamber and a cathode chamber, and hydrogen gas is also generated in the cathode chamber.

[0018] Preferably, the total organic carbon (TOC) content in the tertiary wastewater is 5–10 mg / L;

[0019] The mass ratio of ozone to total organic carbon in the tertiary wastewater is 0.5 to 1.5:1.

[0020] The catalyst is a supported catalyst, and the mass ratio of the catalyst to the ozone is 0.2 to 0.4:1;

[0021] The ozone catalytic oxidation treatment also yields oxygen, and the oxygen is then used in the microbial electrolysis treatment.

[0022] This invention provides a reverse osmosis treatment method for organic wastewater, comprising the following steps:

[0023] The four-stage treated wastewater obtained by the reverse osmosis pretreatment method for organic wastewater described in the above technical solution is subjected to reverse osmosis treatment to obtain reverse osmosis pure water and reverse osmosis concentrate.

[0024] Preferably, it further includes: using a portion of the reverse osmosis pure water in the microbial electrolysis treatment;

[0025] The reverse osmosis concentrate has a conductivity ≥20000μs / cm and a total dissolved solids (TDS) ≥14000mg / L;

[0026] The reverse osmosis concentrate undergoes energy recovery treatment, which involves converting the water pressure of the reverse osmosis concentrate into electrical energy.

[0027] This invention provides an organic wastewater reverse osmosis treatment system, comprising a sedimentation tank, a magnetic flocculation device, a microbial electrolysis tank, an ozone treatment device, and a reverse osmosis device connected in sequence.

[0028] The magnetic flocculation device includes a coagulation unit, a magnetic mixing unit, a coagulation aid unit, and a sedimentation unit connected in sequence.

[0029] Preferably, the bottom of the sedimentation tank is provided with a sludge discharge plate, which is used to discharge sludge from the sedimentation tank;

[0030] The sedimentation unit is equipped with a wastewater discharge outlet;

[0031] The microbial electrolysis cell is provided with an anode chamber and a cathode chamber. The anode chamber is provided with an anode, a gas outlet and a liquid inlet. The cathode chamber is provided with a cathode, a gas inlet and a liquid inlet and a gas outlet.

[0032] The ozone treatment device is provided with an oxygen outlet, which is connected to the gas inlet of the cathode chamber;

[0033] The reverse osmosis device is provided with an inlet, a pure water outlet and a concentrated water outlet, and a return pipe is provided between the concentrated water outlet and the inlet;

[0034] The organic wastewater reverse osmosis treatment system also includes a magnetic powder recovery device, an energy recovery treatment device, a pure water storage tank, and a hydrogen storage tank;

[0035] The inlet of the magnetic powder recovery device is connected to the wastewater discharge outlet of the sedimentation unit;

[0036] The inlet of the energy recovery treatment device is connected to the concentrate outlet of the reverse osmosis device;

[0037] The inlet of the pure water storage tank is connected to the pure water outlet of the reverse osmosis unit;

[0038] The inlet of the hydrogen storage tank is connected to the gas outlet of the cathode chamber.

[0039] This invention provides a reverse osmosis pretreatment method for organic wastewater, comprising the following steps: (1) subjecting the organic wastewater to gravity sedimentation to obtain primary treated wastewater; (2) subjecting the primary treated wastewater to magnetic flocculation to obtain secondary treated wastewater and flocculated wastewater, wherein the magnetic flocculation treatment includes sequentially adding a coagulant, a magnetic mixing agent, and a coagulant aid to the primary treated wastewater, followed by flocculation sedimentation; (3) subjecting the secondary treated wastewater to microbial electrolysis to obtain carbon dioxide and tertiary treated wastewater; (4) introducing ozone into the tertiary treated wastewater and performing ozone catalytic oxidation under the catalytic conditions of a catalyst to degrade small molecule organic pollutants in the tertiary treated wastewater to obtain quaternary treated wastewater. The organic wastewater reverse osmosis pretreatment method provided by this invention, by rationally setting up pretreatment steps before reverse osmosis treatment, utilizes the synergistic effects of gravity sedimentation, magnetic flocculation, microbial electrolysis, and ozone catalytic oxidation to significantly reduce the concentration of organic and biological pollutants in the wastewater. This effectively reduces the adhesion of pollutants to the surface of the reverse osmosis membrane used in subsequent reverse osmosis treatment, precisely reduces the risk of organic and biological fouling of the raw water, significantly improves the operational stability and water treatment efficiency of high-recovery-rate reverse osmosis systems, reduces energy consumption and maintenance frequency, and extends the service life of membrane modules. It provides a breakthrough solution for the efficient and stable operation of high-recovery-rate reverse osmosis systems. At the same time, the organic wastewater reverse osmosis pretreatment method provided by this invention enables the corresponding treatment system to leverage its advantages of integration and small footprint, solving the problem of land scarcity, and possessing both economic value and forward-looking industry application. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the reverse osmosis treatment system for organic wastewater provided by the present invention;

[0041] Figure 2 A schematic diagram of the working principle of the sedimentation tank in the reverse osmosis treatment system for organic wastewater provided by the present invention;

[0042] Figure 3 A schematic diagram of the magnetic flocculation device in the reverse osmosis treatment system for organic wastewater provided by the present invention.

[0043] Figure 4 Schematic diagram of the working principle of the microbial electrolysis cell of the reverse osmosis treatment system for organic wastewater provided by the present invention;

[0044] Figure 5 Gas path diagram of the ozone treatment device in the reverse osmosis treatment system for organic wastewater provided by the present invention;

[0045] Figure 6 A schematic diagram illustrating the working principle of the reverse osmosis unit, pure water storage tank, and energy recovery treatment unit in the organic wastewater reverse osmosis treatment system provided by the present invention.

[0046] Figure 7 A schematic diagram of the working principle of the magnetic powder recovery device in the reverse osmosis treatment system for organic wastewater provided by the present invention.

[0047] In the diagram: 1 is a sedimentation tank, 2 is a magnetic flocculation device, 3 is a microbial electrolysis cell, 4 is an ozone treatment device, 5 is a reverse osmosis device, 6 is a magnetic powder recovery device, 7 is an energy recovery treatment device, 8 is a pure water storage tank, and 9 is a hydrogen storage tank. Detailed Implementation

[0048] This invention provides a reverse osmosis pretreatment method for organic wastewater, comprising the following steps:

[0049] (1) The organic wastewater is subjected to gravity sedimentation treatment to obtain primary treated wastewater;

[0050] (2) The primary wastewater is subjected to magnetic flocculation treatment to obtain secondary wastewater and flocculated wastewater. The magnetic flocculation treatment includes adding coagulant, magnetic mixing agent and coagulant aid to the primary wastewater in sequence, and then performing flocculation and sedimentation.

[0051] (3) The secondary treated wastewater is subjected to microbial electrolysis to obtain carbon dioxide and tertiary treated wastewater;

[0052] (4) Ozone is introduced into the tertiary wastewater and ozone catalytic oxidation is carried out under the catalytic conditions of the catalyst to degrade the organic pollutants in the tertiary wastewater and obtain quaternary wastewater.

[0053] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0054] This invention treats organic wastewater by gravity sedimentation to obtain primary treated wastewater. In this invention, the organic wastewater is preferably high in organic matter. The preferred concentration of suspended solids (SS) in the organic wastewater is 50–200 mg / L; the preferred total organic matter (TOC) value is 3000–10000 mg / L; the preferred total organic matter (COD) value is 5000–20000 mg / L; and the preferred concentration of suspended solids (SS) in the primary treated wastewater is 20–40 mg / L. This invention effectively removes suspended solids from the organic wastewater through gravity sedimentation.

[0055] In this invention, the gravity sedimentation is preferably carried out in a sedimentation tank. During the gravity sedimentation process, the suspended solids in the organic wastewater gradually settle under the action of gravity, achieving solid-liquid separation of the suspended solids in the organic wastewater, thereby obtaining primary treated wastewater.

[0056] After obtaining the primary treated wastewater, this invention subjectes the primary treated wastewater to magnetic flocculation treatment to obtain secondary treated wastewater and flocculated wastewater. The magnetic flocculation treatment includes sequentially adding a coagulant, a magnetic mixing agent, and a coagulant aid to the primary treated wastewater, followed by flocculation and sedimentation. In this invention, the magnetic flocculation treatment utilizes the synergistic effect of the coagulant, magnetic mixing agent, and coagulant aid to effectively remove suspended solids (SS) and organic matter from the primary treated wastewater, effectively reducing the chemical oxygen demand (COD) of the primary treated wastewater. In this invention, after the magnetic flocculation treatment, the removal rate of suspended solids (SS) in the primary treated wastewater is preferably 70-90%; the removal rate of organic matter is preferably 30-50%. The COD of the primary treated wastewater is reduced by 30-50%.

[0057] In this invention, the coagulant preferably comprises polyaluminum chloride (PAC). The mass ratio of the coagulant to the volume of the organic wastewater is preferably (5-50) mg:1 L. In this invention, the coagulant is added under stirring conditions. After the PAC is added to the primary treated wastewater, it undergoes hydrolysis, and the resulting hydrolysis product is a positively charged colloid. The reaction principle is as follows:

[0058] Al n (OH) m Cl 3n-m +mH2O→nAl(OH)3 (colloid)+(3n-m)Cl - ;

[0059] PAC neutralizes negatively charged suspended particles (such as colloids and organic matter) in primary treated wastewater, thus destabilizing them.

[0060] In this invention, the magnetic mixer preferably comprises iron(III) oxide (Fe3O4). The preferred mass ratio of the magnetic mixer to the organic wastewater is (10-100) mg:1 L. The magnetic mixer is preferably added under stirring conditions. After being added to the primary treated wastewater, the magnetic mixer forms high-density magnetic flocs, increasing floc density and accelerating sedimentation. This invention preferably achieves this by controlling the amount of magnetic mixer used, effectively increasing the density of the magnetic flocs and thus accelerating their sedimentation.

[0061] In this invention, the coagulant preferably comprises anionic polyacrylamide and / or nonionic polyacrylamide. The mass ratio of the coagulant to the volume of the organic wastewater is preferably (1-10) mg:1 L. In this invention, the coagulant can aggregate small flocs into large and dense flocs through molecular chain bridging. By controlling the dosage of the coagulant, this invention can effectively promote the agglomeration of small floating floc particles in water. In this invention, during the flocculation and sedimentation process, magnetic flocs settle, resulting in secondary treated wastewater and flocculated wastewater. The flocculated wastewater contains magnetic flocs and is also referred to as magnetic flocculation wastewater in this invention.

[0062] In this invention, the pH value of the magnetic flocculation treatment is preferably 6-7. The magnetic flocculation treatment preferably uses carbon dioxide to adjust the pH value. This invention preferably controls the pH of the magnetic flocculation treatment to be weakly acidic, which is more conducive to the generation and sedimentation of magnetic flocs. This invention preferably introduces carbon dioxide into the primary treated wastewater to adjust the pH value in at least one of the following situations: before adding the coagulant, simultaneously with adding the coagulant, after adding the coagulant and before adding the magnetic flocculation agent, simultaneously with adding the magnetic flocculation agent, and after adding the magnetic flocculation agent.

[0063] In this invention, after obtaining the flocculated wastewater, the invention preferably further includes: recovering the magnetic mixing agent from the flocculated wastewater to obtain recovered magnetic mixing agent and non-magnetic substances. The recovered magnetic mixing agent is preferably reused in the magnetic flocculation treatment, thereby achieving recycling. This invention effectively saves costs by recovering the magnetic mixing agent from the flocculated wastewater and recycling it.

[0064] In this invention, the magnetic flocculation treatment greatly reduces the hydraulic retention time and occupies only 1 / 20 of the area of ​​a conventional coagulation flocculation tank, thus reducing the system's floor space.

[0065] After obtaining the secondary treated wastewater, the present invention further treats the secondary treated wastewater by microbial electrolysis to obtain carbon dioxide and tertiary treated wastewater. In this invention, the microbial electrolysis treatment is preferably carried out in a microbial electrolysis cell. The microbial electrolysis cell preferably includes an anode chamber and a cathode chamber, wherein the anode chamber is provided with an anode and the cathode chamber is provided with a cathode. In this invention, the anode chamber is preferably provided with a support material. The support material is laid or fixed near the anode area, providing a growth carrier for microorganisms with electrogenic capacity and capable of colonizing the anode surface. This allows the microorganisms to oxidize and decompose organic matter on their surface through an isoelectronic transfer medium. Simultaneously, the good conductivity of the support material itself ensures the efficient transfer of electrons released from the decomposition of organic matter to the external circuit, achieving effective electron extraction, ensuring the stable operation of the microbial electrolysis cell, and facilitating the material and energy conversion process of the entire system. In this invention, the support material is preferably a carbon-based material, preferably including carbon cloth and / or carbon paper. In this invention, the cathode material is preferably an iron-chromium alloy. The iron-chromium alloy has good conductivity.

[0066] Preferably, under an applied load, the secondary treated wastewater is transported to the anode chamber for microbial electrolysis. In this invention, the anode primarily utilizes electroactive microorganisms, such as Geobacter and Shewanella. These microorganisms can colonize the anode surface and possess direct or indirect electron transfer capabilities, oxidizing and decomposing organic matter. The reaction principle is as follows: Under the action of the microorganisms:

[0067] CH2O (general formula of organic matter) + H2O → CO2 + 4H+ + +4e - ;

[0068] Electrons are released and transferred to the anode.

[0069] In this invention, the supporting material for the anode is preferably a carrier for the growth of the microorganisms, which also ensures efficient electron transfer to the external circuit. In this invention, the released electrons are transferred to the cathode in the cathode chamber via the external circuit power supply, simultaneously generating H₂. + In this invention, the cathode chamber produces H. + Hydrogen gas is then obtained in the cathode chamber, and the reaction is as follows:

[0070] 2H + +2e - →H2↑.

[0071] In this invention, the hydrogen generated during the microbial electrolysis process is preferably transported to a hydrogen storage tank.

[0072] In this invention, after the organic matter in the secondary treated wastewater is decomposed, the concentration of organic matter decreases, resulting in tertiary treated wastewater.

[0073] In this invention, after obtaining carbon dioxide through microbial electrolysis, the invention preferably further includes using the carbon dioxide obtained through microbial electrolysis for pH adjustment in magnetic flocculation treatment.

[0074] In this invention, the microbial electrolysis is carried out under conditions where oxygen is introduced. The oxygen is preferably introduced into the cathode chamber for the reaction. The microbial electrolysis also yields hydrogen gas.

[0075] In this invention, the total organic carbon (TOC) content in the tertiary wastewater is preferably 5-10 mg / L.

[0076] In this invention, the microbial electrolysis treatment process achieves a dual-functional coupling of pollutant degradation and energy recovery. While efficiently degrading organic matter, the process also generates current through electron transfer driven by microbial metabolism, constructing a green treatment system that requires no additional high-intensity energy input. This invention fully utilizes the direct participation of microorganisms in electron transfer within sludge, overcoming the limitations of traditional wastewater treatment that focuses solely on pollutant removal. It pioneers a new path of "bioelectrochemical synergistic transformation" in wastewater resource recovery, providing a solution for treating high-concentration organic wastewater that combines environmental benefits with energy value.

[0077] After obtaining tertiary treated wastewater, this invention introduces ozone into the tertiary treated wastewater and performs ozone catalytic oxidation treatment under the catalytic conditions of a catalyst to degrade the organic pollutants in the tertiary treated wastewater, resulting in quaternary treated wastewater. In this invention, the total organic carbon (TOC) content in the tertiary treated wastewater is preferably 5-10 mg / L. The mass ratio of ozone to total organic carbon in the tertiary treated wastewater is preferably 0.5-1.5:1. The catalyst is preferably a metal oxide or a supported catalyst, and the support for the supported catalyst is preferably TiO2 and / or Al2O3. The mass ratio of the catalyst to ozone is preferably 0.2-0.4:1. In this invention, the principle of ozone catalytic oxidation treatment is as follows: utilizing the strong oxidizing property of ozone (O3), pollutant degradation is achieved under the action of a catalyst. Specifically, the catalyst promotes the decomposition of ozone, generating hydroxyl radicals (·OH) with strong oxidizing properties, thereby achieving efficient degradation of organic pollutants. In this invention, the ozone catalytic oxidation treatment is a heterogeneous catalytic oxidation. The catalyst used in this invention is insoluble in water and has good stability and recyclability.

[0078] In this invention, the ozone catalytic oxidation treatment is divided into three stages: First, after ozone dissolves in the liquid phase, it is adsorbed and activated by the catalyst, generating hydroxyl radicals; second, organic pollutants are adsorbed on the catalyst surface, forming surface chelates; finally, the hydroxyl radicals react with the surface chelates to degrade the organic pollutants. The main chemical reaction involved in the ozone catalytic oxidation treatment is the decomposition of ozone under the action of the catalyst to generate hydroxyl radicals.

[0079] O3 + M (catalyst) → ·OH + O2 + M;

[0080] And the reaction of hydroxyl radicals with organic matter (where RH represents organic matter):

[0081] ·OH + RH → R· + H2O.

[0082] This invention utilizes ozone catalytic oxidation treatment, where the catalyst catalyzes the decomposition of ozone to generate ·OH, which oxidizes and degrades pollutants in water. Therefore, this invention can more effectively reduce the concentration of organic matter entering the subsequent reverse osmosis process.

[0083] In this invention, after ozone catalytic oxidation treatment, the concentration of organic matter in the tertiary wastewater is reduced by 40-70%. Furthermore, the concentration of recalcitrant small-molecule organic matter in the water is significantly reduced.

[0084] In this invention, the ozone catalytic oxidation treatment also yields oxygen. After obtaining the oxygen, the invention preferably further includes using the oxygen in the microbial electrolysis treatment.

[0085] This invention provides a reverse osmosis treatment method for organic wastewater, comprising the following steps:

[0086] The four-stage treated wastewater obtained by the reverse osmosis pretreatment method for organic wastewater described in the above technical solution is subjected to reverse osmosis treatment to obtain reverse osmosis pure water and reverse osmosis concentrate.

[0087] In this invention, the reverse osmosis treatment is carried out in a reverse osmosis device. During the reverse osmosis treatment, pressure is applied to force water molecules to pass through the semi-permeable membrane of the reverse osmosis device, thereby effectively removing dissolved salts, microorganisms and other impurities from the water.

[0088] In this invention, the molding pressure of the reverse osmosis treatment is preferably 5 to 15 Bar.

[0089] In this invention, the reverse osmosis pure water preferably has a TDS of ≤50mg / L, a conductivity of ≤100μS / cm, a pH of 6.5-7.5, a TOC of 0.5-1mg / L, and a microbial index of ≤10CFU / mL.

[0090] The reverse osmosis treatment preferably employs a full reflux of concentrate until the conductivity of the reverse osmosis concentrate is preferably ≥20000 μs / cm (20000 μs / cm in the example) and the total dissolved solids (TDS) is preferably ≥14000 mg / L (14000 mg / L in the example). The reverse osmosis concentrate is then discharged.

[0091] This invention employs a concentrated water full recirculation operation mode for reverse osmosis treatment, which can enhance the overall operating efficiency of the system. When the concentrated water concentration rises to a set threshold, this invention preferably discharges the concentrated water to prevent membrane fouling and scaling.

[0092] In this invention, after obtaining the reverse osmosis pure water, the invention preferably further includes: using a portion of the reverse osmosis pure water in the microbial electrolysis treatment for hydrogen generation. The remaining reverse osmosis pure water is preferably stored in a pure water tank. This invention preferably utilizes the reverse osmosis pure water as a water source for different purposes, depending on the needs of the reverse osmosis treatment.

[0093] In this invention, the discharged reverse osmosis concentrate is preferably subjected to energy recovery treatment, which is pre-selected as converting the water pressure of the reverse osmosis concentrate into electrical energy.

[0094] This invention provides an organic wastewater reverse osmosis treatment system, comprising a sedimentation tank, a magnetic flocculation device, a microbial electrolysis tank, an ozone treatment device, and a reverse osmosis device connected in sequence.

[0095] The magnetic flocculation device includes a coagulation unit, a magnetic mixing unit, a coagulation aid unit, and a sedimentation unit connected in sequence.

[0096] The organic wastewater reverse osmosis treatment system provided by this invention includes a sedimentation tank. In this invention, the sedimentation tank includes an inlet and an outlet. The working principle of the sedimentation tank is based on gravity settling. When organic wastewater flows into the sedimentation tank, suspended solids in the water gradually settle due to gravity and accumulate at the bottom of the tank, while clear water flows out from the outlet, achieving solid-liquid separation.

[0097] In this invention, the number of sedimentation tanks is preferably two, namely a first sedimentation tank and a second sedimentation tank. The two sedimentation tanks are preferably connected in parallel. A sludge discharge plate is provided at the bottom of each sedimentation tank for discharging sludge from the sedimentation tank. The sludge discharge plate is preferably made of a corrosion-resistant material.

[0098] In this invention, the preferred method of sedimentation is as follows: organic wastewater continuously flows into the sedimentation tank, suspended solids continuously settle, and sludge gradually accumulates at the bottom of the tank; when the sludge accumulates to a certain extent, the sedimentation tank stops receiving water, and the internal sludge discharge plate is energized and begins to rotate, pushing out the sludge accumulated at the bottom of the sedimentation tank to complete the sludge discharge operation; then the sludge discharge plate returns to its original position, the sedimentation tank resumes receiving water, and sedimentation treatment continues.

[0099] In this invention, when the sludge discharge plate of the first sedimentation tank is working, the sludge discharge plate of the second sedimentation tank is stationary; when the sludge discharge plate of the second sedimentation tank is working, the sludge discharge plate of the first sedimentation tank is stationary.

[0100] In this invention, the sedimentation tank efficiently separates suspended solids from organic wastewater through gravity settling, reducing the pollutant load on subsequent treatment units and ensuring the stability of the overall treatment process. This invention employs two sedimentation tanks connected in parallel, enabling continuous wastewater treatment and improving wastewater purification efficiency.

[0101] The present invention provides a sludge discharge plate in the sedimentation tank, which can automatically complete the sludge discharge without frequent manual intervention. This reduces the time cost of equipment downtime for sludge discharge, ensures the continuity of the sedimentation process, improves the stability and convenience of sedimentation tank operation, and optimizes the overall efficiency of wastewater treatment.

[0102] In this invention, the sludge discharge plate is preferably located at the bottom of the sedimentation tank. The sludge discharge plate is preferably located at the bottom of the sedimentation tank near the sludge collection hopper or in a sludge collection area with a low bottom slope. This location facilitates direct contact with the settled sludge, allowing for the collection and discharging of the sludge through the rotational movement of the discharge plate.

[0103] In this invention, the settled sludge gradually accumulates at the bottom of the tank above the sludge discharge plate, which is located below or in direct contact with the sludge layer. When the sludge discharge plate rotates, it can directly push or scrape the accumulated sludge above, causing it to move towards the discharge port.

[0104] In this invention, after the organic wastewater is introduced, the sludge settles to the bottom of the sedimentation tank under gravity and gradually accumulates at the bottom slope or in the sludge collection hopper. These areas are the final accumulation points of the sludge due to gravity settling. This invention facilitates centralized collection and discharge of the sludge by installing sludge discharge plates.

[0105] In this invention, the mud discharge plate preferably rotates in a circular motion around a fixed axis, typically driven by a motor through a transmission device to achieve timed or continuous rotation. The fixed axis preferably includes a central shaft or a side shaft.

[0106] In this invention, the shape of the sludge discharge plate preferably includes a fan shape, an arc shape, or a flat plate shape. The material of the sludge discharge plate is preferably stainless steel, high-density polyethylene (HDPE), or polyvinyl chloride (PVC) to ensure stable operation in wastewater environments over a long period of time.

[0107] In this invention, the edge of the mud discharge plate preferably has an inclined angle to enhance the mud pushing effect.

[0108] In this invention, the mud-discharging plate is preferably provided with a mud-scraping blade on its edge to enhance the mud-pushing effect.

[0109] In this invention, the sludge discharge plate is preferably close to the bottom of the tank, but with a small gap. When the sludge discharge plate rotates, the angle between the plate and the bottom of the tank is used to scrape the accumulated sludge from the bottom of the tank and push it to the sludge discharge port. The sludge is then discharged from the sedimentation tank through the sludge discharge pipe.

[0110] In this invention, the sludge discharge plate is preferably combined with gravity sludge discharge or pump suction sludge discharge to ensure efficient sludge removal and maintain the separation effect of the sedimentation tank.

[0111] The organic wastewater reverse osmosis treatment system provided by this invention includes a magnetic flocculation device connected to the effluent outlet of the sedimentation tank. In this invention, the magnetic flocculation device includes a coagulation unit, a magnetic mixing unit, a coagulation aid unit, and a sedimentation unit connected in sequence.

[0112] In this invention, the coagulation unit is preferably a coagulation tank. The magnetic mixing unit is preferably a magnetic mixing tank. The coagulation aid unit is preferably a coagulation aid tank, and the sedimentation unit is preferably a sedimentation tank.

[0113] In this invention, after the effluent from the sedimentation tank passes through the magnetic flocculation device, the primary treated wastewater from the sedimentation tank first flows into the coagulation tank. A coagulant is added and stirred to hydrolyze the wastewater, producing positively charged colloids. These colloids neutralize negatively charged suspended particles (such as colloids and organic matter) in the wastewater, destabilizing them. Then, the water flows into the magnetic mixing tank, where a magnetic mixing agent (such as Fe3O4) is added and stirred to form high-density magnetic flocs, increasing floc density and accelerating sedimentation. Next, the water enters the coagulation aid tank, where a coagulation aid is added, which can aggregate small flocs into large, dense flocs through molecular chain bridging. The mixed liquid flows into the sedimentation tank, and after the magnetic flocs settle, the clarified water is discharged into the microbial electrolysis tank. In this invention, the sedimentation unit is equipped with a wastewater discharge outlet. The wastewater flocculated by the magnetic mixing agent at the bottom flows to the magnetic powder recovery device. The magnetic mixing agent is pumped back into the magnetic mixing tank, while non-magnetic substances are discharged as wastewater. The magnetic mixing agent adsorbed by the magnetic powder recovery device is removed from the magnetic field through backwashing and recycled back to the magnetic mixing tank.

[0114] In this invention, the carbon dioxide generated in the anode chamber of the microbial electrolysis cell is introduced into the magnetic flocculation device, which can adjust the pH of the wastewater to a slightly acidic state, which is beneficial to accelerating the formation of flocs.

[0115] The magnetic flocculation device provided by this invention improves the removal rate of SS and COD while shortening the sedimentation time. In terms of cost control, this invention can maximize the recycling of magnetic mixing agent, saving costs. The organic wastewater reverse osmosis treatment system provided by this invention realizes the magnetic mixing agent recycling mode. The construction of coagulant, magnetic mixing agent and system adopts a modular assembly design, which is conducive to rapid construction and convenient for flexible expansion in the later stage.

[0116] The organic wastewater reverse osmosis treatment system provided by the present invention includes a microbial electrolysis cell connected to the outlet of the magnetic flocculation device.

[0117] In this invention, the microbial electrolysis cell is provided with an anode chamber and a cathode chamber. The anode chamber is provided with an anode, a gas outlet and a liquid inlet. The cathode chamber is provided with a cathode, a gas inlet and a liquid inlet and a gas outlet.

[0118] In this invention, the secondary treated wastewater is transported to the anode chamber of the microbial electrolysis cell. The reverse osmosis pure water is introduced into the cathode chamber of the microbial electrolysis cell.

[0119] In this invention, the anode chamber primarily utilizes electroactive microorganisms. These microorganisms can colonize the surface of the support material within the anode chamber, oxidizing organic matter in wastewater (such as glucose, acetic acid, and COD in sewage) and releasing electrons (e). - ) and proton (H + The anode is supported by a carbon-based material (such as carbon cloth or carbon paper), which not only provides a carrier for microbial growth but also ensures efficient electron transfer to the external circuit. The released electrons are transferred to the chemical cathode via the external circuit power supply, simultaneously generating H₂. + The generated carbon dioxide is supplied to the magnetic flocculation device to adjust the pH value within it. In this invention, after the organic matter in the influent of the magnetic flocculation device is decomposed, the secondary treated wastewater with reduced organic matter concentration flows into the anode of the microbial electrolysis tank and then into the ozone processor for further treatment.

[0120] The organic wastewater reverse osmosis treatment system provided by this invention includes an ozone treatment device connected to the outlet of the microbial electrolysis cell. In this invention, the ozone treatment device is provided with an oxygen outlet, which is connected to the gas inlet of the cathode chamber. Preferably, the ozone treatment device includes a gas-water contact device. The gas-water contact device preferably includes a microporous diffuser or a bubble column. The ozone fully contacts the tertiary treated wastewater through the gas-water contact device, and simultaneously, a catalyst catalyzes the decomposition of ozone to generate ·OH, oxidizing and degrading pollutants in the water. Therefore, it can more effectively reduce the concentration of organic matter entering the subsequent controllable recovery rate reverse osmosis process.

[0121] The organic wastewater reverse osmosis treatment system provided by this invention includes a reverse osmosis device connected to the outlet of the ozone treatment device. In this invention, the reverse osmosis device is provided with an inlet, a pure water outlet, and a concentrated water outlet, and a return pipe is provided between the concentrated water outlet and the inlet.

[0122] In this invention, the reverse osmosis device applies pressure to force water molecules through a semi-permeable membrane, effectively removing dissolved salts, microorganisms, and other impurities from the water. The reverse osmosis device is equipped with a recovery control mechanism, which optimizes water recovery rate and improves water production efficiency while ensuring water quality. The reverse osmosis device features a preferred concentrate circulation structure, allowing concentrate to flow back to the inlet, enhancing overall system efficiency and reducing floor space requirements. When the concentrate concentration rises to a set threshold, the valves in the system automatically open to discharge the concentrate, preventing membrane fouling and scaling.

[0123] The organic wastewater reverse osmosis treatment system provided by the present invention preferably includes a magnetic powder recovery device. The inlet of the magnetic powder recovery device is connected to the wastewater discharge outlet of the sedimentation unit.

[0124] In this invention, the magnetic powder recovery device receives wastewater from the magnetic flocculation device. The wastewater from the magnetic flocculation device mainly contains a magnetic mixer (the main component of which is Fe3O4).

[0125] In this invention, the magnetic powder recovery and treatment device preferably performs magnetic powder recovery. Magnetic powder is obtained from sludge via a magnetic separator and then added back as a magnetic additive to the magnetic flocculation process, achieving the recycling of magnetic powder, reducing operating costs, and improving the system's environmental sustainability.

[0126] The organic wastewater reverse osmosis treatment system provided by the present invention preferably includes an energy recovery treatment device. The inlet of the energy recovery treatment device is connected to the concentrate outlet of the reverse osmosis device.

[0127] The organic wastewater reverse osmosis treatment system provided by the present invention preferably includes a pure water storage tank. The inlet of the pure water storage tank is connected to the pure water outlet of the reverse osmosis device.

[0128] The organic wastewater reverse osmosis treatment system provided by the present invention preferably includes a hydrogen storage tank. In the present invention, the inlet of the hydrogen storage tank is connected to the gas outlet of the cathode chamber.

[0129] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0130] Example 1

[0131] This embodiment provides a reverse osmosis treatment method for organic wastewater, employing... Figure 1 The organic wastewater reverse osmosis treatment system shown includes the following steps:

[0132] Figure 2 This is a schematic diagram illustrating the structure and working principle of the sedimentation tank in this embodiment. High-organic wastewater (SS concentration of 200 mg / L, TOC preferably 10000 mg / L, COD 20000 mg / L) flows into the sedimentation tank, which consists of a first sedimentation tank and a second sedimentation tank connected in parallel. Suspended solids in the organic wastewater gradually settle due to gravity and accumulate at the bottom of the tank, while the clear water flows out from the top, achieving solid-liquid separation. Primary treated wastewater is obtained. The SS concentration in the primary treated wastewater is 40 mg / L.

[0133] Figure 3 The diagram shows the structure and working principle of the magnetic flocculation device in this embodiment. The primary treated wastewater enters the magnetic flocculation device. First, the primary treated wastewater flows from the sedimentation tank into the coagulation tank, where a coagulant (PAC, with a mass ratio of coagulant to organic wastewater of 10 mg: 1 L) is added. Stirring causes hydrolysis, producing positively charged colloids that neutralize negatively charged suspended particles (such as colloids and organic matter) in the wastewater, destabilizing them. Then, the primary treated wastewater flows into the magnetic mixing tank, where a magnetic mixing agent (Fe3O4, with a mass ratio of magnetic mixing agent to organic wastewater of 20 mg: 1 L) is added. Stirring forms high-density magnetic flocs, increasing floc density and accelerating sedimentation. Next, the primary treated wastewater enters the coagulation aid tank, where a coagulation aid (anionic polyacrylamide, with a mass ratio of coagulation aid to organic wastewater of 5 mg: 1 L) is added. This aid aggregates small flocs into large, dense flocs through molecular chain bridging. The mixed liquid flows into the sedimentation tank, where the magnetic flocs settle, and the clarified water is discharged into the microbial electrolysis tank. The bottom magnetic powder flocculation wastewater flows to the magnetic powder recovery device. Figure 7 The magnetic mixing agent flows back into the magnetic mixing tank via a return pump, while non-magnetic substances are discharged as wastewater. The magnetic powder adsorbed by the magnetic powder recovery device is removed from the magnetic field through backwashing and recycled back to the magnetic mixing tank. In this embodiment, carbon dioxide generated at the anode of the microbial electrolysis cell is introduced into the magnetic mixing tank to adjust the pH of the primary treated wastewater to 6-7, which is beneficial for accelerating floc formation.

[0134] After magnetic flocculation treatment, secondary treated wastewater is obtained. In this embodiment, after magnetic flocculation treatment: the removal rate of suspended solids (SS) in the primary treated wastewater is 90%; the removal rate of organic matter is 50%. The COD of the primary treated wastewater is reduced by 50%.

[0135] Figure 4 This is a schematic diagram illustrating the working principle of the microbial electrolysis cell in the reverse osmosis treatment system for organic wastewater provided by this invention. Secondary treated wastewater is transported to the anode chamber. Pure water produced by the reverse osmosis unit is stored in a pure water storage tank and flows from the tank to the cathode chamber.

[0136] The anode chamber primarily utilizes electrogenic microorganisms to oxidize and decompose organic matter, releasing electrons which are then transferred to the anode. These electrons are efficiently transported to the external circuit. The released electrons are then transferred to the cathode via the external circuit power supply, simultaneously generating H₂. + The carbon dioxide generated in the anode chamber is supplied to the magnetic flocculation device to adjust the pH value within the device. After the organic matter in the secondary treated wastewater is decomposed, the resulting tertiary treated wastewater with a reduced organic matter concentration enters the ozone processor for further treatment. The total organic carbon (TOC) content in the tertiary treated wastewater is 5 mg / L.

[0137] Figure 5 This invention provides a gas path diagram for the ozone treatment device in a reverse osmosis system for organic wastewater. Tertiary wastewater enters the ozone treatment device, with an ozone mass ratio of 1:1 to the total organic carbon in the wastewater. The catalyst is a metal oxide, with a catalyst-to-ozone mass ratio of 0.3:1. Ozone diffuses into the tertiary wastewater through a gas-water contact device (microporous diffuser) within the ozone treatment device, ensuring thorough contact. Simultaneously, the catalyst catalyzes the decomposition of ozone to generate ·OH, which oxidizes and degrades pollutants in the tertiary wastewater, resulting in quaternary wastewater. After ozone catalytic oxidation treatment, the concentration of organic matter in the tertiary wastewater is reduced by 70%.

[0138] Figure 6 The diagram illustrates the working principle of the reverse osmosis unit, pure water storage tank, and energy recovery unit in the organic wastewater reverse osmosis treatment system provided by this invention. Water molecules in the quaternary treated wastewater pass through the reverse osmosis membrane (semi-permeable membrane), effectively removing dissolved salts, microorganisms, and other impurities. The reverse osmosis unit is equipped with a recovery control mechanism, which optimizes water recovery rate and improves water production efficiency while ensuring water quality. The reverse osmosis unit adopts a circulation structure, allowing concentrated water to flow back to the inlet end to enhance the overall system operating efficiency. When the concentrated water concentration rises to a set threshold (conductivity 20000 μs / cm, TDS 14000 mg / L), the valve in the system automatically opens to discharge the concentrated water, preventing membrane fouling and scaling.

[0139] The purified water obtained through the reverse osmosis system is transported to a pure water storage tank for storage. In this example, the obtained reverse osmosis pure water has a TDS ≤ 50 mg / L, conductivity ≤ 100 μS / cm, pH 6.5–7.5, TOC 0.5–1 mg / L, and microbial indicators: total bacterial count ≤ 10 CFU / mL.

[0140] The concentrated water then passes through an energy recovery device, where residual pressure energy is recovered to power the microbial electrolysis cell, improving the overall system's energy efficiency. This process achieves the synergistic recovery and recycling of water resources and energy.

[0141] In this embodiment, the magnetic powder recovery device receives wastewater from the magnetic flocculation device. The wastewater from the magnetic flocculation device mainly contains a magnetic binder (Fe3O4). By using a magnetic separator to separate the magnetic powder, it can be reused as a magnetic binder. This embodiment achieves the recycling of iron resources, reduces operating costs, and improves the environmental sustainability of the system.

[0142] As can be seen from the above embodiments, the present invention, by rationally setting up pretreatment processes before reverse osmosis treatment, utilizes the synergistic effects of gravity sedimentation, magnetic flocculation, microbial electrolysis, and ozone catalytic oxidation to significantly reduce the concentration of organic and biological pollutants in organic wastewater. This effectively reduces the adhesion of pollutants to the surface of the reverse osmosis membrane used in subsequent reverse osmosis treatment, precisely reduces the risk of organic and biological fouling of raw water, significantly improves the operational stability and water treatment efficiency of high-recovery-rate reverse osmosis systems, reduces energy consumption, reduces maintenance frequency, and extends the service life of membrane modules. It provides a breakthrough solution for the efficient and stable operation of high-recovery-rate reverse osmosis systems, possessing both economic value and forward-looking industry application prospects.

[0143] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for reverse osmosis pretreatment of organic wastewater, characterized in that, Includes the following steps: (1) The organic wastewater is subjected to gravity sedimentation treatment to obtain primary treated wastewater; (2) The primary wastewater is subjected to magnetic flocculation treatment to obtain secondary wastewater and flocculated wastewater. The magnetic flocculation treatment includes adding a coagulant, a magnetic mixing agent and a coagulant aid to the primary wastewater in sequence. The coagulant includes polyaluminum chloride, the magnetic mixing agent includes iron(III) oxide, and the coagulant aid includes anionic polyacrylamide and / or nonionic polyacrylamide. The pH value of the magnetic flocculation treatment is 6~7, and then flocculation and sedimentation are carried out. (3) The secondary wastewater is subjected to microbial electrolysis to obtain carbon dioxide and tertiary wastewater; the microbial electrolysis is carried out under anaerobic conditions of an anode and an oxygen-supplying cathode, and the carbon dioxide obtained from the microbial electrolysis is used to adjust the pH value of the magnetic flocculation treatment. (4) Ozone is introduced into the tertiary wastewater and ozone catalytic oxidation is carried out under the catalytic conditions of the catalyst to degrade the organic pollutants in the tertiary wastewater to obtain quaternary wastewater; the ozone catalytic oxidation also yields oxygen, and the oxygen is then used in the microbial electrolysis treatment.

2. The method for reverse osmosis pretreatment of organic wastewater according to claim 1, characterized in that, The mass ratio of the coagulant to the volume of the organic wastewater is (5~50) mg: 1L; The mass ratio of the magnetic mixer to the volume of the organic wastewater is (10~100) mg: 1L; The mass ratio of the coagulant to the volume of the organic wastewater is (1~10) mg: 1L; The magnetic flocculation treatment uses carbon dioxide to adjust the pH value.

3. The method for reverse osmosis pretreatment of organic wastewater according to claim 1 or 2, characterized in that, After obtaining the flocculated wastewater, the process further includes: recovering the flocculated wastewater using a magnetic mixer to obtain a recovered magnetic mixer and non-magnetic substances, wherein the recovered magnetic mixer is reused in step (2).

4. The method for reverse osmosis pretreatment of organic wastewater according to claim 1, characterized in that, The microbial electrolysis treatment is carried out in a microbial electrolysis cell, which includes an anode chamber and a cathode chamber, and hydrogen gas is also generated in the cathode chamber.

5. The method for reverse osmosis pretreatment of organic wastewater according to claim 1 or 4, characterized in that, The total organic carbon content in the tertiary wastewater is 5~10 mg / L; The mass ratio of ozone to total organic carbon in the tertiary wastewater is 0.5~1.5:1; The catalyst is a supported catalyst, and the mass ratio of the catalyst to the ozone is 0.2~0.4:

1.

6. A method for treating organic wastewater via reverse osmosis, characterized in that, Includes the following steps: The four-stage treated wastewater obtained by the reverse osmosis pretreatment method for organic wastewater according to any one of claims 1 to 5 is subjected to reverse osmosis treatment to obtain reverse osmosis pure water and reverse osmosis concentrate.

7. The reverse osmosis treatment method for organic wastewater according to claim 6, characterized in that, Also includes: A portion of the reverse osmosis pure water is used in the microbial electrolysis treatment; The conductivity of the reverse osmosis concentrate is ≥20000 μs / cm, and the total dissolved solids are ≥14000 mg / L; The reverse osmosis concentrate undergoes energy recovery treatment, which involves converting the water pressure of the reverse osmosis concentrate into electrical energy.

8. An organic wastewater reverse osmosis treatment system, characterized in that, The system comprises a sedimentation tank, a magnetic flocculation device, a microbial electrolysis tank, an ozone treatment device, and a reverse osmosis device, connected in sequence. The sedimentation tank has a sludge discharge plate at its bottom for discharging sludge. The magnetic flocculation device includes a coagulation unit, a magnetic mixing unit, a coagulation aid unit, and a sedimentation unit, connected in sequence, with a wastewater discharge outlet in the sedimentation unit. The microbial electrolysis tank has an anode chamber and a cathode chamber. The anode chamber contains an anode and has a gas outlet and a liquid inlet. The cathode chamber contains a cathode and has a gas inlet, a liquid inlet, and a gas outlet. Carbon dioxide generated in the anode chamber of the microbial electrolysis tank is introduced into the magnetic flocculation device to adjust the pH of the wastewater to a slightly acidic level, which is beneficial for accelerating floc formation. The ozone treatment device has an oxygen outlet connected to the gas inlet of the cathode chamber. The reverse osmosis device has an inlet, a pure water outlet, and a concentrated water outlet, with a return pipe connecting the concentrated water outlet and the inlet. The organic wastewater reverse osmosis treatment system also includes a magnetic powder recovery device, an energy recovery treatment device, a pure water storage tank, and a hydrogen storage tank; the inlet of the magnetic powder recovery device is connected to the wastewater discharge outlet of the sedimentation unit; the inlet of the energy recovery treatment device is connected to the concentrate outlet of the reverse osmosis device; the inlet of the pure water storage tank is connected to the pure water outlet of the reverse osmosis device; and the inlet of the hydrogen storage tank is connected to the gas outlet of the cathode chamber.

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