Organic wastewater purification treatment system

Abstract

The invention discloses an organic wastewater purification treatment system which comprises a pretreatment unit, a persulfate advanced oxidation unit, a biological treatment unit, a disinfection tank and a sludge treatment unit which are sequentially connected, and the persulfate advanced oxidation unit adopts a composite activation system of persulfate and a transition metal catalyst. The biological treatment unit is used for treating wastewater and is provided with a synergistic mixing system of an anchor-paddle composite water impeller and an ultrasonic device, efficient decomposition of organic matters in the wastewater is realized, the biological treatment unit comprises an anaerobic-anoxic-aerobic moving bed bio-membrane reactor (MBBR) system and a double-sludge reflux system which are connected in series in three stages, and nitrogen and phosphorus removal is realized through dissolved oxygen gradient control. The method has the characteristics of environmental friendliness, high treatment efficiency, excellent quality of produced water, high system stability and the like, can realize the dual purposes of efficient treatment and resource utilization of organic wastewater, and is particularly suitable for treatment of refractory organic industrial wastewater such as antibiotic pharmaceutical wastewater and pesticide intermediate wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and specifically relates to an organic wastewater purification treatment system, which is particularly suitable for the efficient deep treatment of industrial wastewater such as antibiotics and pesticide intermediates. Background Art

[0002] With the rapid development of the pharmaceutical industry, the discharge of industrial wastewater containing difficult-to-degrade organic pollutants such as antibiotics and organic solvents continues to increase. This type of wastewater is characterized by complex composition, high biological toxicity, and poor biodegradability, making it difficult to achieve stable discharge standards using traditional treatment processes.

[0003] Currently, the mainstream treatment technologies for wastewater containing organic pollutants include physical and chemical methods and biological treatment. Physical and chemical adsorption methods (such as activated carbon adsorption) suffer from limited removal rates for low-concentration pollutants, difficulty in adsorbent regeneration, and high operating costs. Physical and chemical coagulation and sedimentation methods are effective for removing organic matter with a molecular weight greater than 3000 Daltons (Da), but have low removal rates for small-molecule antibiotics and produce large amounts of chemical sludge. Therefore, physical and chemical methods only achieve phase transfer of pollutants and fail to disrupt their molecular structure, posing a risk of secondary pollution. Biological treatment methods, primarily activated sludge, offer low operating costs, but the inhibitory effect of antibiotics in wastewater on microorganisms can lead to reduced nitrifying bacteria activity and low total nitrogen removal rates. Furthermore, antibiotics accumulate in sludge, creating sludge disposal challenges.

[0004] In recent years, persulfate advanced oxidation technology has been widely used due to the sulfate radical (SO4 - •) has attracted much attention due to its strong oxidizing properties and long half-life, but in actual applications, it has been found that the amount of oxidant added to this technology is too high, which leads to increased treatment costs, and the oxidation intermediates may produce more toxic halogenated organics (such as when treating chlorine-containing antibiotics), and the catalyst is easily deactivated in a wide pH range, and the reaction efficiency is significantly reduced.

[0005] The existing "oxidation + biology" combination process mostly uses Fenton oxidation as pretreatment, which has problems such as large iron sludge production, residual H2O2 in the effluent of the oxidation unit (which will inhibit the microbial activity of subsequent biological units), unreasonable distribution of chemical oxygen demand (COD) removal load, and high overall energy consumption. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention constructs a highly efficient integrated organic wastewater purification and treatment system, which achieves deep removal and resource utilization of difficult-to-degrade organic wastewater by optimizing the synergistic mechanism of persulfate oxidation and biological treatment.

[0007] The present invention adopts the following technical solution: an organic wastewater purification and treatment system, comprising a water inlet, a pretreatment unit, a persulfate advanced oxidation unit, a biological treatment unit, a disinfection tank, a water outlet and a sludge treatment unit connected in sequence, characterized in that: the pretreatment unit comprises a grid decontamination machine, a cyclone grit chamber, a pH adjustment tank and a primary sedimentation tank, which respectively perform slag removal, sand removal, pH adjustment and precipitation treatment on the wastewater; the persulfate advanced oxidation unit comprises a persulfate advanced oxidation reactor, a persulfate addition device and a catalyst addition device, and decomposes organic matter in the wastewater through the activation effect of persulfate and the catalyst; the biological treatment unit comprises an anaerobic tank, an anoxic MBBR tank, an aerobic MBBR tank, a secondary sedimentation tank and a coagulation sedimentation tank, and achieves nitrogen and phosphorus removal through dissolved oxygen gradient control; the sludge treatment unit comprises a sludge thickening tank and a sludge dewatering device, and the sludge thickening tank is connected to the persulfate advanced oxidation unit and the biological treatment unit.

[0008] Furthermore, the persulfate advanced oxidation reactor is provided with an anchor-paddle composite flow propeller and an ultrasonic device to form a strong shear flow field and an ultrasonic cavitation field, thereby promoting efficient activation of persulfate and the catalyst. The persulfate is selected from one of potassium hydrogen persulfate (KHSO5) and sodium persulfate (Na2S2O8) or a combination thereof, and the catalyst is a ferrous sulfate / cobalt sulfate (FeSO4 / CoSO4) composite catalyst. The hydraulic retention time in the persulfate advanced oxidation reactor is 1.5-2.5 h.

[0009] Furthermore, the biological treatment unit includes a three-stage anaerobic-anoxic-aerobic moving bed biofilm reactor (MBBR) system connected in series, the anaerobic tank is provided with a submersible mixer, the anoxic MBBR tank is provided with a submersible mixer and a perforated aeration pipe, the aerobic MBBR tank is provided with a submersible mixer and a spherical aeration plate, the perforated aeration pipe and the spherical aeration plate are connected to the aerator, the dissolved oxygen in the anaerobic tank, the anoxic MBBR tank and the aerobic MBBR tank are controlled to <0.2 mg / L, 0.2-0.5 mg / L and 2.5-4.0 mg / L, respectively, and denitrification and phosphorus removal are achieved by dissolved oxygen gradient control.

[0010] Furthermore, the anoxic MBBR tank and the aerobic MBBR tank are both filled with a specific surface area of ​​≥500 m 2 / m 3 The cylindrical porous filler has a filling rate of 30%-40% and a filling density of 0.94-0.96 g / cm 3 .

[0011] Furthermore, the biological treatment unit is provided with a dual sludge return system, an internal return pipe and an internal return pump are provided between the anoxic MBBR tank and the aerobic MBBR tank, and the return ratio is controlled at 150%-400%, and an external return pipe and an external return pump are provided between the anaerobic tank and the secondary sedimentation tank, and the return ratio is controlled at 40%-150%.

[0012] Furthermore, the sludge produced by the persulfate advanced oxidation reactor, the secondary sedimentation tank, and the coagulation sedimentation tank are respectively transported to the sludge concentration tank through sludge pumps, and are transported out for harmless disposal after being treated by the sludge dewatering device. The sludge dewatering device includes a high-pressure plate and frame filter press and a microwave dryer.

[0013] The beneficial effects of the present invention are as follows: (1) by adopting a persulfate and catalyst activation system, the present invention improves the utilization rate of persulfate, and fully degrades the macromolecular organic matter in the sewage by chain breaking, thereby improving the toxicity resistance of the biological treatment unit, enhancing the stability of the system, and improving the treatment efficiency of the entire system. The effluent water quality can stably meet the Class A standard of the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (GB 18918-2002).

[0014] (2) In the persulfate advanced oxidation unit of the present invention, the catalyst can be recycled multiple times, thereby reducing the cost of reagents, improving the processing efficiency of the complete system, and reducing the overall energy consumption. Therefore, compared with the traditional process, the operating cost of the present invention is lower.

[0015] (3) The present invention generates less oxidation by-products and has a significant sludge reduction effect, which is beneficial to controlling secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the embodiments and accompanying drawings.

[0018] like Figure 1As shown, an organic wastewater purification system comprises a water inlet 1, a pretreatment unit 2, a persulfate advanced oxidation unit 3, a biological treatment unit 4, a disinfection tank 5, a water outlet 6 and a sludge treatment unit 7 connected in sequence, characterized in that the pretreatment unit 2 comprises a screen decontamination machine 21, a cyclone grit chamber 22, a pH adjustment tank 23 and a primary sedimentation tank 24, which respectively perform slag removal, sand removal, pH adjustment and precipitation treatment on the wastewater, the persulfate advanced oxidation unit 3 comprises a persulfate advanced oxidation reactor 31, a persulfate addition device 32 and a catalyst addition device 33, and decomposes organic matter in the wastewater through the activation effect of persulfate and the catalyst, the biological treatment unit 4 comprises an anaerobic tank 41, an anoxic MBBR tank 42, an aerobic MBBR tank 43, a secondary sedimentation tank 44, and a coagulation sedimentation tank 45, and achieves nitrogen and phosphorus removal through dissolved oxygen gradient control, the sludge treatment unit 7 comprises a sludge thickening tank 71 and a sludge dewatering device 72, and the sludge thickening tank 71 is connected to the persulfate advanced oxidation unit 3 and the biological treatment unit 4.

[0019] The persulfate advanced oxidation reactor 31 is equipped with an anchor-paddle composite flow propeller and an ultrasonic device to form a strong shear flow field and an ultrasonic cavitation field, thereby promoting the efficient activation of persulfate and the catalyst. The persulfate is selected from potassium hydrogen persulfate (KHSO5) and sodium persulfate (Na2S2O8) or a combination thereof, and the catalyst is a ferrous sulfate / cobalt sulfate (FeSO4 / CoSO4) composite catalyst. The hydraulic retention time in the persulfate advanced oxidation reactor 31 is 1.5-2.5 h, and the power density of the ultrasonic device is 0.1-1.0 W / cm 3 , operating frequency 20-100 kHz.

[0020] The biological treatment unit 4 includes a three-stage anaerobic-anoxic-aerobic MBBR system in series. A submerged mixer is provided in the anaerobic tank 41, a submerged mixer and a perforated aeration pipe are provided in the anoxic MBBR tank 42, and a submerged mixer and a spherical aeration plate are provided in the aerobic MBBR tank 43. The perforated aeration pipe and the spherical aeration plate are connected to the aerator. The dissolved oxygen in the anaerobic tank 41, the anoxic MBBR tank 42 and the aerobic MBBR tank 43 is controlled to be <0.2 mg / L, 0.2-0.5 mg / L and 2.5-4.0 mg / L respectively. Nitrogen and phosphorus removal are achieved by controlling the dissolved oxygen gradient. The anoxic MBBR tank 42 and the aerobic MBBR tank 43 are both filled with a specific surface area ≥500 m 2 / m 3 The cylindrical porous filler has a filling rate of 30%-40% and a filling density of 0.94-0.96 g / cm 3 .

[0021] In addition, a dual sludge return system is installed in the biological treatment unit 4. An internal return pipe and an internal return pump are installed between the anoxic MBBR tank 42 and the aerobic MBBR tank 43, with a return ratio controlled between 150% and 400%. An external return pipe and an external return pump are installed between the anaerobic tank 41 and the secondary sedimentation tank 44, with a return ratio controlled between 40% and 150%. During operation, sludge produced by the persulfate advanced oxidation reactor 31, the secondary sedimentation tank 44, and the coagulation sedimentation tank 45 is respectively transported to the sludge thickening tank 71 via sludge pumps. After treatment in the sludge dewatering device 72, it is transported for harmless disposal. The sludge dewatering device 72 uses plate and frame filter pressing combined with microwave drying technology, and the final sludge moisture content is ≤45%.

[0022] This invention establishes a synergistic system combining persulfate catalytic oxidation with a moving bed biofilm reactor (MBBR). By improving the stability of the oxidation unit catalyst, enhancing the toxicity resistance of the biological unit, and optimizing the sludge disposal system, it achieves the dual goals of efficient treatment and resource utilization of organic wastewater. This treatment system overcomes the technical challenges of low oxidation efficiency, strong bioinhibition, and high sludge production in traditional processes. It is particularly suitable for treating difficult-to-degrade organic industrial wastewater, such as antibiotic pharmaceutical wastewater and pesticide intermediate wastewater.

[0023] The above content describes the technical solution of the present invention in detail, but does not limit the scope of protection of the present invention. Ordinary technicians in this technical field can also make improvements and modifications on this basis, but these improvements and modifications are within the scope of protection of the claims of the present invention.

Claims

1. An organic wastewater purification system comprising a water inlet, a pretreatment unit, a persulfate advanced oxidation unit, a biological treatment unit, a disinfection tank, a water outlet, and a sludge treatment unit connected in sequence, characterized in that: The pretreatment unit includes a screen decontamination machine, a cyclone grit chamber, a pH adjustment tank and a primary sedimentation tank, which respectively perform slag removal, sand removal, pH adjustment and precipitation treatment on the wastewater. The persulfate advanced oxidation unit includes a persulfate advanced oxidation reactor, a persulfate addition device and a catalyst addition device, which decomposes organic matter in the wastewater through the activation effect of persulfate and catalyst. The biological treatment unit includes an anaerobic tank, an anoxic MBBR tank, an aerobic MBBR tank, a secondary sedimentation tank and a coagulation sedimentation tank, which achieves nitrogen and phosphorus removal through dissolved oxygen gradient control. The sludge treatment unit includes a sludge thickening tank and a sludge dewatering device, and the sludge thickening tank is connected to the persulfate advanced oxidation unit and the biological treatment unit.

2. The organic wastewater purification system according to claim 1, characterized in that: The persulfate advanced oxidation reactor is equipped with an anchor-paddle composite flow propeller and an ultrasonic device, with a hydraulic retention time of 1.5-2.5 hours. The persulfate is selected from potassium hydrogen persulfate (KHSO5) and sodium persulfate (Na2S2O8) or a combination thereof, and the catalyst is a ferrous sulfate / cobalt sulfate (FeSO4 / CoSO4) composite catalyst.

3. The organic wastewater purification system according to claim 1, characterized in that: The biological treatment unit includes a three-stage anaerobic-anoxic-aerobic MBBR system connected in series. A submersible mixer is provided in the anaerobic tank, a submersible mixer and a perforated aeration pipe are provided in the anoxic MBBR tank, and a submersible mixer and a spherical aeration disk are provided in the aerobic MBBR tank. The perforated aeration pipe and the spherical aeration disk are connected to the aerator. The dissolved oxygen in the anaerobic tank, the anoxic MBBR tank, and the aerobic MBBR tank is controlled to be <0.2 mg / L, 0.2-0.5 mg / L, and 2.5-4.0 mg / L, respectively. Denitrification and phosphorus removal are achieved through dissolved oxygen gradient control.

4. The organic wastewater purification system according to claim 1, characterized in that: The anoxic MBBR tank and the aerobic MBBR tank are both filled with a specific surface area of ​​≥500 m 2 / m 3 The cylindrical porous filler has a filling rate of 30%-40% and a filling density of 0.94-0.96 g / cm 3 .

5. The organic wastewater purification system according to claim 1, characterized in that: The biological treatment unit is equipped with a dual sludge return system. An internal return pipe and an internal return pump are provided between the anoxic MBBR tank and the aerobic MBBR tank, and the return ratio is controlled at 150%-400%. An external return pipe and an external return pump are provided between the anaerobic tank and the secondary sedimentation tank, and the return ratio is controlled at 40%-150%.

6. The organic wastewater purification system according to claim 1, characterized in that: The sludge produced by the persulfate advanced oxidation reactor, the secondary sedimentation tank, and the coagulation sedimentation tank is respectively transported to the sludge concentration tank through sludge pumps, and is transported out for harmless disposal after being treated by the sludge dewatering device. The sludge dewatering device includes a high-pressure plate and frame filter press and a microwave dryer.

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