A system for treating total nitrogen in refractory wastewater

Abstract

The utility model discloses a kind of total nitrogen of difficult degradation wastewater synergic treatment system, belong to sewage treatment technical field.The total nitrogen synergic treatment system includes water inlet, anoxic tank, aerobic tank, device tank body, effluent recirculation pipeline, nitrogen recovery device and water outlet;The device tank body inside is equipped with heterotrophic denitrification filler area, sulfate-reducing bacteria filler area and sulfur autotrophic denitrification filler area;Gas seal baffle and inclined baffle are equipped in the upper portion of the device tank body.The system couples heterotrophic denitrification, sulfur autotrophic denitrification and sulfate-reducing bacteria, without additional carbon source, sulfur source and alkalinity, reduce sulfate pollution and H + The system overflow in sulfur autotrophic denitrification process, total nitrogen load is high, total nitrogen treatment effect is strong, and effluent quality is good.

Description

Technical Field

[0001] This utility model patent relates to the field of wastewater treatment technology, specifically to a system for the synergistic treatment of total nitrogen in recalcitrant wastewater. Background Technology

[0002] Recalcitrant wastewater (such as pharmaceutical, petrochemical, coking, and landfill leachate) faces multiple technical challenges in total nitrogen treatment due to its complex composition, high toxicity, and diverse nitrogen forms (organic nitrogen, ammonia nitrogen, nitrate nitrogen, etc.).

[0003] Currently, biological denitrification is the core technology for treating total nitrogen in recalcitrant wastewater. Biological denitrification is a classic denitrification technology based on microbial metabolism. By connecting anaerobic denitrification and aerobic nitrification processes in series, it achieves efficient removal of total nitrogen from wastewater. This technology has high and stable denitrification efficiency, with a total nitrogen removal rate typically between 70% and 85%. It also features a simple process structure and low operation and maintenance costs.

[0004] However, biological nitrogen removal (especially denitrification) has limited efficiency in treating high-concentration nitrogen wastewater (e.g., TN > 100 mg / L) or recalcitrant wastewater containing toxic substances. It requires pretreatment (e.g., advanced oxidation) or upgrades to A² / O or short-cut nitrification-denitrification processes. However, denitrification relies on carbon sources for energy, consuming large amounts of oxygen and alkalinity. Furthermore, recalcitrant wastewater generally has a low C / N ratio or poor carbon source availability, necessitating the addition of chemical carbon sources such as methanol and sodium acetate, which is costly and poses a risk of secondary pollution. Sulfate autotrophic denitrification, as a relatively new technology, offers good total nitrogen removal, requires no carbon source, and produces less sludge. However, sulfur ions are easily lost in sulfur autotrophic denitrification, leading to subsequent sulfate pollution and sulfide biotoxicity. The process also generates H₂ during sulfur autotrophic denitrification. + This leads to a decrease in system pH, inhibiting the metabolic activity of denitrifying bacteria. In actual engineering projects, to remove total nitrogen from recalcitrant wastewater, it is often necessary to design a two-stage anoxic-aerobic tank or a three-stage anoxic-aerobic tank, which requires a large area, high construction costs, and high carbon source dosage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this utility model patent is to provide a co-treatment system for total nitrogen in recalcitrant wastewater. This system has a small footprint, does not require additional carbon sources, sulfur sources, or alkalinity, has a high total nitrogen removal rate, and produces good effluent quality.

[0006] To achieve the above objectives, this utility model patent adopts the following technical solution:

[0007] This invention provides a co-treatment system for total nitrogen in recalcitrant wastewater, comprising an inlet 1, an anoxic tank 2, an aerobic tank 4, a micro-anoxic tank 5, a device tank 100, an effluent return pipe 101, a nitrogen recovery device 111, and an outlet 110. The inlet 1 is connected to the anoxic tank 2, which is connected to the aerobic tank 4 via a guide hole 3. The aerobic tank 4 and the effluent return pipe 101 are connected to the device tank 100 via a one-way valve 102. The device tank 100 contains a heterotrophic denitrification packing zone 105, a sulfate-reducing bacteria packing zone 106, and a sulfur autotrophic denitrification packing zone 107. This system couples heterotrophic denitrification, sulfur autotrophic denitrification, and sulfate-reducing bacteria, eliminating the need for external carbon sources and alkalinity, thus reducing sulfate pollution and H₂O. + The system overflows, the total nitrogen load is high, the treatment effect is strong, and the effluent quality is good.

[0008] Furthermore, flanges 103 are provided on the upper and lower sides of the heterotrophic denitrification packing zone 105, the sulfate-reducing bacteria packing zone 106, and the sulfur autotrophic denitrification packing zone 107, respectively, to achieve a detachable, sealed, and stable connection between the three zones and the device tank 100, effectively preventing packing leakage, ensuring the system's sealing and pressure stability, and adapting to the special operating conditions of the water treatment system.

[0009] Furthermore, an unfilled packing zone is provided between the heterotrophic denitrification packing zone 105, the sulfate-reducing bacteria packing zone 106, and the sulfur autotrophic denitrification packing zone 107. Difficult-to-degrade wastewater can be fully mixed in this zone before entering the next packing zone. Backwashing can be set in this zone when the packing caking occurs.

[0010] Furthermore, fiberglass gratings 104 are respectively provided between the upper and lower sides of the heterotrophic denitrification packing zone 105 and the flange 103 for supporting and fixing the heterotrophic denitrification packing; fiberglass gratings 104 are respectively provided between the upper and lower sides of the sulfate-reducing bacteria packing zone 106 and the flange 103 for supporting and fixing the sulfate-reducing bacteria packing; fiberglass gratings 104 are respectively provided between the upper and lower sides of the sulfur autotrophic denitrification packing zone 107 and the flange 103 for supporting and fixing the sulfur autotrophic denitrification packing.

[0011] As a preferred embodiment, the fiberglass grating 104 is covered with 316L steel wire mesh to further intercept the filler and prevent leakage.

[0012] Furthermore, a nitrogen recovery device 111 is provided on the upper part of the device tank 100, and an inclined baffle 108 and an air-sealing baffle 109 are provided on the lower side of the nitrogen recovery device 111. Wastewater and nitrogen pass through the sulfur autotrophic denitrification packing zone 107 from bottom to top and collide with the air-sealing baffle 109 and the inclined baffle 108 to achieve gas-liquid separation. The inclined baffle 108 ensures smooth return flow and reduces interference between water and gas. Wastewater flows out through the outlet 110, and nitrogen is recovered through the nitrogen recovery device 111.

[0013] In summary, this utility model has the following advantages:

[0014] (1) The total nitrogen co-treatment system for recalcitrant wastewater couples heterotrophic denitrification, sulfate reduction, and sulfur autotrophic denitrification. This achieves alkalinity complementarity while simultaneously consuming and removing hydrogen ions and sulfate ions produced by sulfur autotrophic bacteria. The heterotrophic bacteria generate alkalinity during the reduction of nitrate and nitrite nitrogen to produce nitrogen gas, while the sulfur autotrophic bacteria consume alkalinity during the reduction of nitrate nitrogen, ensuring stable alkalinity and effluent parameters. The H+ produced during sulfur autotrophic denitrification... + And sulfate is returned to the unit tank, H + The alkalinity produced by heterotrophic denitrification can be neutralized, and sulfate-reducing bacteria can reduce sulfate to sulfides, such as H2S and HS-, under anaerobic conditions. - S 2- These generated sulfides act as electron acceptors for the sulfur autotrophic denitrification process, while the residual nitrate nitrogen in the heterotrophic denitrification effluent serves as an electron donor. Nitrate nitrogen is then converted into nitrogen gas by the sulfur autotrophic denitrifying bacteria. The entire system requires no external carbon source, sulfur source, or alkalinity, reducing sulfate pollution and H+ overflow during the sulfur autotrophic denitrification process. It boasts a high total nitrogen load, strong total nitrogen treatment effect, and excellent effluent quality.

[0015] (2) The whole system has a small footprint, high efficiency, simple design and compact structure. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] In the diagram, 1-inlet, 2-anoxic tank, 3-diversion tunnel, 4-aerobic tank, 5-microanoxic tank, 100-device tank, 101-outlet return pipe, 102-check valve, 103-flange, 104-fiberglass grating, 105-heterotrophic denitrification packing zone, 106-sulfate-reducing bacteria packing zone, 107-sulfate autotrophic denitrification packing zone, 108-sloping baffle, 109-air seal baffle, 110-outlet, 111-nitrogen recovery device. Detailed Implementation

[0018] The present utility model patent will be further described in detail below with reference to the accompanying drawings and examples:

[0019] The directional terms described in this utility model patent, such as "front," "back," "up," "down," "left," "right," and "center," are based on the directional relationships shown in the accompanying drawings. They are only for the convenience of describing this utility model patent and simplifying the description, and are not intended to indicate specific orientations that the device or equipment must have. Therefore, they should not be construed as limitations on this utility model patent.

[0020] The purpose of this utility model patent is to provide a synergistic treatment system for total nitrogen in recalcitrant wastewater. This system couples heterotrophic denitrification, sulfur autotrophic denitrification, and sulfate-reducing bacteria, eliminating the need for external carbon sources, sulfur sources, and alkalinity, thereby reducing sulfate pollution and H₂O pollution during the sulfur autotrophic denitrification process. + The system overflowed, the total nitrogen load was high, the total nitrogen treatment effect was strong, and the effluent quality was good.

[0021] To achieve the above objectives, this utility model patent adopts the following implementation method:

[0022] Please refer to Figure 1 This is an embodiment of the synergistic treatment device for total nitrogen in recalcitrant wastewater according to the present invention. Its features include: an inlet (1), an anoxic tank (2), an aerobic tank (4), a micro-anoxic tank (5), a device tank (100), an effluent return pipe (101), a nitrogen recovery device (111), and an outlet (110); the inlet (1) is connected to the anoxic tank (2), and the anoxic tank (2) is connected to the aerobic tank (4) through a guide hole (3); the aerobic tank (4) and the effluent return pipe (101) are connected to the device tank (100) through a one-way valve (102). The device tank 100 is equipped with a heterotrophic denitrification packing zone 105, a sulfate-reducing bacteria packing zone 106, and a sulfur autotrophic denitrification packing zone 107. Flanges 103 are provided on the upper and lower sides of the heterotrophic denitrification packing zone 105, the sulfate-reducing bacteria packing zone 106, and the sulfur autotrophic denitrification packing zone 107, respectively. A nitrogen recovery device 111 is provided on the upper part of the device tank 100, and an inclined baffle 108 and an air seal baffle 109 are provided on the lower side of the nitrogen recovery device 111.

[0023] During operation, wastewater enters the anoxic tank 2 through inlet 1. The effluent from anoxic tank 2 flows through guide tunnel 3 into aerobic tank 4. Aerobic tank 4 converts ammonia nitrogen in the influent into nitrate nitrogen. Part of the nitrified liquid is returned to the influent pipe and then enters anoxic tank 2, where it degrades the nitrate nitrogen in the returned nitrified liquid into nitrogen gas. The effluent from aerobic tank 4 passes through a micro-anoxic tank 5, where residual oxygen is consumed, before entering the device tank 100. The wastewater flows upwards through the heterotrophic denitrification packing zone 105, the sulfate-reducing bacteria packing zone 106, and the sulfur autotrophic denitrification packing zone 107. This upward flow allows the gas produced during denitrification to escape easily and contributes to the formation of an anaerobic environment. Nitrification occurs in aerobic tank 4, converting ammonia nitrogen into nitrate nitrogen. The nitrate nitrogen then enters the heterotrophic denitrification packing zone 105, where it undergoes another heterotrophic denitrification reaction, with some of the nitrate nitrogen being converted into nitrogen gas. When carbon sources are insufficient, a bypass branch can be installed to connect from anoxic tank 2 to the bottom of the device tank 100. The effluent from heterotrophic denitrification packing zone 105 enters the sulfate-reducing bacteria packing zone 106, where sulfate-reducing bacteria reduce sulfate to sulfides such as H2S and HS- under anaerobic conditions. - S 2- The effluent from the sulfate-reducing bacteria packing zone 106 enters the sulfur autotrophic denitrification packing zone 107. The generated sulfides act as electron acceptors, receiving electrons from nitrate nitrogen in the water sample. Nitrate nitrogen is converted to nitrogen gas by the sulfur autotrophic denitrifying bacteria, and the sulfides are ultimately converted to sulfate ions, effectively treating nitrogen oxides in the wastewater. A large amount of H₂ is generated during the sulfur autotrophic denitrification process. + and SO − Therefore, an effluent return pipe 101 is installed on the upper side of the sulfur autotrophic denitrification packing zone 107. The effluent treated by sulfur autotrophic denitrification enters the heterotrophic denitrification packing zone 105 through the effluent return pipe 101. A large amount of H2O will be generated during the sulfur autotrophic denitrification process. + The alkalinity produced by heterotrophic denitrification can be neutralized to prevent the effluent pH from becoming too low. A nitrogen recovery device 111 is installed at the top of the tank 100, with an inclined baffle 108 and an air-sealing baffle 109 located below it. Wastewater and nitrogen flow upwards through the sulfur autotrophic denitrification packing zone 107 and collide with the air-sealing baffle 109 and the inclined baffle 108, achieving gas-liquid separation. The inclined baffle 108 ensures smooth backflow and reduces interference between water and gas. Wastewater flows out through the outlet 110, and nitrogen is recovered through the nitrogen recovery device 111.

[0024] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A system for the synergistic treatment of total nitrogen in recalcitrant wastewater, characterized in that: It includes an inlet (1), an anoxic tank (2), an aerobic tank (4), a micro-anoxic tank (5), a device tank (100), an effluent return pipe (101), a nitrogen recovery device (111), and an outlet (110); the inlet (1) is connected to the anoxic tank (2), and the anoxic tank (2) is connected to the aerobic tank (4) through a guide hole (3); the effluent from the aerobic tank (4) passes through the micro-anoxic tank (5) and is connected to the device tank (100) through a one-way valve (102) via the effluent return pipe (101); the device tank (110) The device (100) is equipped with a heterotrophic denitrification packing zone (105), a sulfate-reducing bacteria packing zone (106), and a sulfur autotrophic denitrification packing zone (107). Flanges (103) are provided on the upper and lower sides of the heterotrophic denitrification packing zone (105), the sulfate-reducing bacteria packing zone (106), and the sulfur autotrophic denitrification packing zone (107). A nitrogen recovery device (111) is provided on the upper part of the device tank (100), and an inclined baffle (108) and a gas seal baffle (109) are provided on the lower side of the nitrogen recovery device (111).

2. The total nitrogen co-treatment system for recalcitrant wastewater according to claim 1, characterized in that: The upper and lower sides of the heterotrophic denitrification packing zone (105) are respectively provided with fiberglass gratings (104) between the flange (103); the upper and lower sides of the sulfate-reducing bacteria packing zone (106) are respectively provided with fiberglass gratings (104) between the flange (103); the upper and lower sides of the sulfur autotrophic denitrification packing zone (107) are respectively provided with fiberglass gratings (104) between the flange (103).

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