A wastewater treatment process and system for nitrogen-containing organic wastewater

Abstract

The present application relates to a kind of nitrogen-containing organic wastewater wastewater treatment process and system, it relates to organic wastewater treatment technical field.A kind of nitrogen-containing organic wastewater treatment process, nitrogen-containing organic wastewater is sequentially subjected to biochemical reaction precipitation treatment and sulfur autotrophic denitrification treatment;Sulfur autotrophic denitrification treatment includes, to the wastewater after biochemical reaction precipitation treatment sequentially flows through zeolite-gravel layer, sulfur mineral-suspended material layer, calcite-wood chip layer, promotes growth layer and carries out denitrification treatment.The present application is aimed at nitrogen-containing organic wastewater, by the mutual cooperation between biochemical reaction precipitation treatment and sulfur autotrophic denitrification treatment, carbon and nitrogen removal are carried out;COD, ammonia nitrogen and the like are removed after biochemical reaction precipitation treatment, produce nitrate and a small amount of nitrite;And sulfur autotrophic denitrification treatment will nitrate and a small amount of nitrite be finally converted into nitrogen gas and discharged;The mutual cooperation of both, and then reach the efficient carbon and nitrogen removal effect, and no secondary precipitation treatment is needed in process, and process is simple, easy to operate.

Description

Technical Field

[0001] This invention relates to the field of organic wastewater treatment technology, and in particular to a wastewater treatment process and system for nitrogen-containing organic wastewater. Background Technology

[0002] In recent years, with economic and social development, the production of high-nitrogen organic wastewater such as landfill leachate and biogas slurry has been increasing year by year. Single biological treatment methods cannot meet the treatment standards for leachate, and multi-stage AO (anaerobic digestion) and enhanced pretreatment or advanced treatment methods are needed to solve the problem in a coordinated manner. Not only does this require a large area and complex process, but also, due to the large fluctuations in water quality and quantity, it is difficult to maintain stable operation of the process.

[0003] Conventionally, biological nitrogen removal employs nitrification-denitrification processes. However, many high-nitrogen wastewaters lack sufficient carbon sources, resulting in low denitrification efficiency and excessive total nitrogen in the effluent. To address the nitrogen removal challenge of wastewater with low carbon-to-nitrogen ratios, external carbon sources can be added to promote denitrification, but this increases the input of nitrogen removal chemicals. Alternatively, anaerobic ammonia oxidation, short-cut denitrification, and sulfur autotrophic denitrification can also be utilized as biological nitrogen removal processes.

[0004] Among them, sulfur autotrophic denitrification technology is gradually being applied in engineering projects due to its high denitrification efficiency and stable operation. This technology introduces sulfur and utilizes the metabolic processes of microorganisms to reduce nitrate nitrogen in the water, ultimately converting it into nitrogen gas. It removes nitrogen without introducing additional COD, eliminating the risk of COD exceeding standards in the effluent, making it a relatively efficient denitrification process. However, because the sulfur autotrophic denitrification reaction consumes a large amount of alkali, and the wastewater is mainly weakly acidic or neutral, the sulfur autotrophic denitrification reaction is difficult to complete and sustain.

[0005] Chinese invention patent application CN 109809558 A addresses the technical problem of insufficient and unsustainable sulfur autotrophic denitrification reaction by providing a composite denitrification reactor, which includes an acid-base adjustment system. By adding an external acid-base regulator to intervene in the sulfur autotrophic denitrification reaction, the acid and base need to be continuously monitored and adjusted during the process, which increases the cost of denitrification treatment. In addition, in order to prevent the local pH value from being too high or too low, additional stirrers are required during the acid-base adjustment process, making the process more complicated and affecting the denitrification effect.

[0006] Given that nitrogen-containing, especially high-nitrogen organic wastewater is characterized by high organic pollution, high total nitrogen, and large water quality variations, there is an urgent need to develop economical, efficient, and land-saving rapid treatment processes for this type of wastewater, ultimately achieving efficient treatment of nitrogen-containing, especially high-nitrogen organic wastewater. Summary of the Invention

[0007] The problem to be solved by this invention is: how to provide a compact process and system for treating nitrogen-containing, especially high-nitrogen organic wastewater that has a small footprint, simple process flow, and low denitrification cost.

[0008] To address the aforementioned problems, this invention provides a wastewater treatment process and system for treating nitrogen-containing organic wastewater. The process includes biochemical reaction sedimentation treatment and sulfur autotrophic denitrification treatment, allowing the inflowing wastewater to undergo an aerobic reaction, producing nitrate and a small amount of nitrite. The wastewater then passes through a circulating clarifier for sludge sedimentation and separation. Sulfur autotrophic denitrification further converts the nitrate and a small amount of nitrite into nitrogen gas, which is then discharged, thereby removing COD, ammonia nitrogen, nitrate nitrogen, and some phosphorus. Finally, filtration completes the treatment of nitrogen-containing or even high-nitrogen organic wastewater, achieving highly efficient carbon and nitrogen removal. This process, through optimization of the first packing unit, eliminates the need for a system to adjust the pH of the denitrification tank, resulting in a simple process flow and low denitrification costs. Simultaneously, a wastewater treatment system for treating high-nitrogen organic wastewater is also provided. Combined with the above process, this system offers advantages such as small footprint, low denitrification costs, high wastewater treatment efficiency, and good results.

[0009] Specifically:

[0010] This invention discloses a treatment process for nitrogen-containing organic wastewater, wherein the nitrogen-containing organic wastewater is subjected to biochemical reaction precipitation treatment and sulfur autotrophic denitrification treatment in sequence;

[0011] The sulfur autotrophic denitrification treatment includes denitrifying the wastewater after biochemical reaction precipitation by sequentially passing it through a zeolite-gravel layer, a sulfur-based mineral-suspended material layer, a calcite-wood chip layer, and a growth-promoting layer.

[0012] The sulfide minerals in the sulfide mineral-suspended material layer include sulfur and pyrite.

[0013] The growth-promoting layer contains growth-promoting substances, which are selected from one or more of the following: maifanite, basalt, quartz, feldspar, and mica.

[0014] Preferably, in the sulfide minerals, the mass ratio of sulfur to pyrite is (1.5-2.5):1.

[0015] Preferably, the thickness ratio of the sulfide mineral-suspended material layer, the calcite-wood chip layer, and the maifanite layer is (45-90):(3-8):1.

[0016] Preferably, in the sulfide mineral-suspension material layer, the suspension material is a polyethylene hollow column, and the volume ratio of sulfide minerals to suspension material is 1:(3-5).

[0017] Preferably, in the zeolite-gravel layer, the mass ratio of zeolite to gravel is (2-2.5):1.

[0018] Preferably, in the calcite-wood chip layer, the volume ratio of calcite to wood chips is (3-3.5):1.

[0019] Preferably, the zeolite-gravel layer, the sulfide mineral-suspended material layer, the calcite-wood chip layer, and the growth-promoting layer constitute the first packing unit, and the wastewater after the biochemical reaction sedimentation treatment flows through several first packing units for denitrification treatment.

[0020] Preferably, the wastewater is denitrified by the first packing unit and then filtered through the volcanic rock layer.

[0021] The present invention also discloses a treatment system for nitrogen-containing organic wastewater, comprising a biochemical reaction sedimentation tank and a denitrification tank connected in sequence; the biochemical reaction sedimentation tank is used for the biochemical reaction sedimentation treatment of the above-mentioned nitrogen-containing organic wastewater, and the denitrification tank is used for the sulfur autotrophic denitrification treatment of the above-mentioned nitrogen-containing organic wastewater.

[0022] The denitrification tank contains, from bottom to top, a zeolite-gravel layer, a sulfide mineral-suspended material layer, a calcite-wood chip layer, and a growth-promoting layer; the bottom of the denitrification tank has an inlet, and the top has an outlet; the inlet of the denitrification tank is connected to a biochemical reaction sedimentation tank.

[0023] Preferably, the zeolite-gravel layer, the sulfide mineral-suspended material layer, the calcite-wood chip layer, and the growth-promoting layer constitute the first packing unit; the denitrification tank is provided with several first packing units from bottom to top.

[0024] Preferably, the denitrification tank is further provided with a volcanic rock layer, which is located above the first packing unit.

[0025] Preferably, the denitrification tank is further provided with a second packing unit, which is located above the first packing unit; the second packing unit includes, from bottom to top, a zeolite-gravel layer, a sulfide mineral-suspended material layer, a calcite-wood chip layer, a growth-promoting layer, and a volcanic rock layer.

[0026] Preferably, the biochemical reaction sedimentation tank is equipped with an aeration disc at the bottom and a circulating clarifier at the top, with the outlet of the biochemical reaction sedimentation tank located above the circulating clarifier; the outlet of the biochemical reaction sedimentation tank is connected to the inlet of the denitrification tank.

[0027] Preferably, the wastewater treatment system for nitrogen-containing organic wastewater further includes a rapid filter, wherein a filter media layer is provided in the rapid filter; the inlet of the rapid filter is located below the filter media layer, and the outlet of the rapid filter is located above the filter media layer; the inlet of the rapid filter is connected to the outlet of the denitrification tank.

[0028] Preferably, the denitrification tank is equipped with a backwashing device; the backwashing device includes a first backwashing inlet pipe and a first backwashing outlet pipe; the first backwashing inlet pipe is located at the top of the denitrification tank, and the first backwashing outlet pipe is located at the bottom of the denitrification tank.

[0029] Beneficial effects:

[0030] (1) The sulfur autotrophic denitrification treatment in the wastewater treatment process for nitrogen-containing organic wastewater of the present invention, through the setting of a multi-layer packing material of zeolite-gravel layer, sulfur-based mineral-suspended material layer, calcite-wood chip layer and growth-promoting layer (specific setting of the first packing unit), enables the sulfur autotrophic denitrification and part of the heterotrophic denitrification reaction to proceed smoothly, thereby removing nitrate and a small amount of nitrite in the inflowing wastewater. Among them, the proportion of each component in each layer such as sulfur-based mineral-suspended material layer and calcite-wood chip layer is optimized so that the wood chips in the calcite-wood chip layer can provide part of the carbon source required for the heterotrophic denitrification reaction, so that the reaction generates a certain alkalinity, and the calcite provides a certain alkalinity support, ensuring that the alkalinity in the denitrification tank is suitable for the sulfur autotrophic denitrification reaction, thus eliminating the need to add an acid-base adjustment system, eliminating the need to supplement the step of detecting and adjusting the acid-base during the reaction process, and only requiring backwashing when the nitrate concentration in the denitrification tank is too high. The process is simple and easy to operate. The growth-promoting layer contains trace elements and rare earth elements such as K, Na, Ca, Mg, Cu, and Mo, which can promote microbial growth and thus ensure the progress of sulfur autotrophic denitrification and heterotrophic denitrification reactions. A volcanic rock layer can also be set up, which can not only remove impurities from the denitrified wastewater and improve the quality of the effluent, but also prevent the loss of effective components in the sulfur-based mineral-suspended material layer, calcite-wood chip layer and growth-promoting layer to a certain extent, thus ensuring the stable progress of sulfur autotrophic denitrification treatment.

[0031] (2) The wastewater treatment process for nitrogen-containing organic wastewater of the present invention includes the wastewater being subjected to biochemical reaction sedimentation treatment and sulfur autotrophic denitrification treatment in sequence; wherein, the biochemical reaction sedimentation treatment utilizes aeration discs for aeration, so that the inflowing wastewater undergoes an aerobic reaction, and then passes through a circulating clarifier for sludge sedimentation and separation, thereby removing COD, ammonia nitrogen, etc., and producing nitrate and a small amount of nitrite; in the sulfur autotrophic denitrification treatment, sulfur autotrophic denitrification and partial heterotrophic denitrification reactions are used for denitrification treatment, that is, nitrate, a small amount of nitrite, phosphorus, etc. are removed, achieving a highly efficient carbon and nitrogen removal effect; this process does not require the addition of a system for adjusting the pH of the denitrification tank, has a small footprint, a simple process flow, and low denitrification cost. Biochemical precipitation treatment and sulfur autotrophic denitrification treatment can work together. After the biochemical precipitation treatment, ammonia nitrogen and other nitrogen are removed, producing nitrate and nitrite. Meanwhile, the sulfur autotrophic denitrification treatment efficiently converts nitrate and nitrite into nitrogen gas for discharge. The two work together to achieve a highly efficient carbon and nitrogen removal effect. Moreover, no secondary precipitation treatment is required in the process, making the process simpler, easier to operate, and with high carbon and nitrogen removal efficiency.

[0032] (3) The wastewater treatment system for high-nitrogen organic wastewater of the present invention is used for the wastewater treatment process of nitrogen-containing organic wastewater, and includes a biochemical reaction sedimentation tank and a denitrification tank connected in sequence; the biochemical reaction sedimentation tank is used for biochemical reaction sedimentation treatment, and inclined tube packing can be set in the circulating clarifier to enhance the sedimentation effect; the denitrification tank is used for sulfur autotrophic denitrification treatment, and is equipped with a first packing unit and / or a second packing unit, and can also improve the removal effect of nitrate nitrogen by setting several mutually stacked first packing units. The stacked setting does not increase the floor area, and the raw materials of each layer of the first packing unit are widely available and low in cost, which can improve the wastewater treatment effect of the wastewater treatment system while making it have the characteristics of small floor area, simple process flow and low denitrification cost; a rapid filter can also be set to filter and remove impurities from the organic wastewater flowing out of the denitrification tank, further removing suspended particulate matter, impurities, etc. in the organic wastewater, and improving the water quality of the treated wastewater. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the wastewater treatment system for high-nitrogen organic wastewater in Experimental Example 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the wastewater treatment system for high-nitrogen organic wastewater in Experimental Example 2 of the present invention;

[0036] Figure 3 This is a schematic diagram of the denitrification tank in Experimental Example 2 of the present invention;

[0037] Figure 4 This is a schematic diagram of the first packing unit of the present invention;

[0038] Figure 5 This is a schematic diagram of the second packing unit of the present invention;

[0039] Figure 6 This is a schematic diagram of the wastewater treatment system for high-nitrogen organic wastewater in Experimental Example 3 of the present invention.

[0040] Explanation of the markings in the image:

[0041] I-Biochemical reaction precipitation treatment; II-Sulfur autotrophic denitrification treatment; III-Rapid filtration treatment;

[0042] 1-Biological reaction sedimentation tank; 2-Aeration disc; 3-Circulating clarifier; 31-Inclined tube packing; 4-Denitrification tank; 5-First packing unit; a-Zeolite-gravel layer; b-Sulfur mineral-suspended material layer; c-Calcite-wood chip layer; d-Growth promotion layer; 6-Second packing unit; e-Volcanic rock layer; 7-Rapid filter; 8-Filter media layer;

[0043] A1 - Inlet of the biochemical reaction sedimentation tank; A2 - Outlet of the biochemical reaction sedimentation tank; B1 - Inlet of the denitrification tank; B2 - Outlet of the denitrification tank; C1 - Inlet of the rapid filter; C2 - Outlet of the rapid filter; D1 - First backwash inlet pipe; D2 - First backwash outlet pipe; D3 - First air inlet pipe; E1 - Second backwash inlet pipe; E2 - Second backwash outlet pipe; E3 - Second air inlet pipe. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0046] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0047] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0049] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0050] The terms "horizontal," "vertical," and "sag" do not imply that a component must be absolutely horizontal, vertical, or sagging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0051] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] A wastewater treatment process for nitrogen-containing organic wastewater.

[0053] The nitrogen-containing organic wastewater is sequentially subjected to biochemical reaction precipitation treatment and sulfur autotrophic denitrification treatment.

[0054] The sulfur autotrophic denitrification treatment includes denitrifying the wastewater after biochemical reaction precipitation by sequentially passing it through a zeolite-gravel layer, a sulfur-based mineral-suspended material layer, a calcite-wood chip layer, and a growth-promoting layer.

[0055] In the zeolite-gravel layer, the zeolite particle size is 2-4 cm, the gravel particle size is 2-4 cm, and the mass ratio of the zeolite to the gravel is (2-2.5):1; preferably, the height (thickness) of the zeolite-gravel layer does not exceed 15 cm.

[0056] The sulfide minerals in the suspension material layer include sulfur and pyrite. Among the sulfide minerals, the sulfur particle size is no greater than 1 cm, and the pyrite particle size is no greater than 1.5 cm. The mass ratio of sulfur to pyrite is (1.5-2.5):1.

[0057] The suspended material is a hollow polyethylene column with a particle size of 5-7 mm. It acts as a scaffold, suspending the dispersed sulfide minerals and increasing the contact area between the minerals and the organic wastewater, thus facilitating their reaction. Therefore, the height of the suspended material should be greater than the height of the sulfide minerals to ensure proper dispersion; the specific height can be adjusted according to actual needs. The volume ratio of sulfide minerals to suspended material is 1:(3-5).

[0058] In the calcite-wood chip layer, the calcite particle size is no greater than 2 cm, the wood chip particle size is no greater than 1 cm, and the volume ratio of the calcite to the wood chip is (3-3.5):1.

[0059] The growth-promoting layer contains a growth-promoting substance, which is selected from one or more of maifanite, basalt, quartz, feldspar, and mica. Preferably, the particle size of the growth-promoting substance is no greater than 5 cm, and more preferably, no greater than 2 cm.

[0060] The thickness ratio of the sulfide mineral-suspended material layer, the calcite-wood chip layer, and the maifanite layer is (45-90):(3-8):1.

[0061] Preferably, in the chalcogenide mineral-suspension material layer, the suspension material is a hollow polyethylene column.

[0062] The zeolite-gravel layer effectively removes ammonia nitrogen from wastewater through the adsorption and ion exchange of zeolite, while gravel also has a certain removal effect on ammonia nitrogen. The sulfide mineral-suspended material layer provides sulfur-autotrophic microorganisms that use reduced sulfur as an electron donor, NO3-. --N acts as an electron acceptor in the autotrophic denitrification process. Simultaneously, sulfide minerals may contain anaerobic ammonia-oxidizing microorganisms, which generate alkalinity through anaerobic ammonia oxidation (heterotrophic denitrification), supplementing some of the alkalinity consumed in sulfur autotrophic denitrification. The suspended material provides a three-dimensional structure for the sulfide minerals, suspending them and increasing the contact area between the minerals and organic wastewater, thus facilitating their reaction. The calcite-wood chip layer provides a carbon source, enabling the anaerobic ammonia-oxidizing microorganisms in the wastewater to carry out heterotrophic denitrification. It also contains calcium carbonate, which has a certain alkalinity, degrading some nitrate and nitrite ions and providing a small amount of alkalinity, making the pH in the denitrification tank suitable for sulfur autotrophic microorganisms to carry out sulfur autotrophic denitrification. The growth-promoting layer contains trace elements and rare earth elements such as K, Na, Ca, Mg, Cu, and Mo, which promote microbial growth, thereby ensuring the progress of both sulfur autotrophic and heterotrophic denitrification reactions.

[0063] The specific arrangement of multiple layers of packing material, including zeolite-gravel layer, sulfur-based mineral-suspended material layer, calcite-wood chip layer, and growth-promoting layer, makes the conditions in the denitrification tank suitable for sulfur autotrophic and heterotrophic denitrification reactions, thereby improving the removal efficiency of nitrate and nitrite in organic wastewater.

[0064] Preferably, the zeolite and gravel in the zeolite-gravel layer can be mixed with each other; the sulfide minerals in the sulfide mineral-suspension material layer can be mixed with each other and then dispersed on the suspension material; the calcite and wood chips in the calcite-wood chip layer can be mixed with each other.

[0065] The zeolite-gravel layer, sulfide mineral-suspended material layer, calcite-wood chip layer, and growth-promoting layer constitute the first packing unit. The wastewater after biochemical reaction and sedimentation treatment flows through several first packing units for denitrification. By setting up several first packing units, the denitrification effect on nitrogen-containing organic wastewater can be improved. The specific number can be selected according to actual needs.

[0066] After the wastewater undergoes denitrification treatment in the first packing unit, it can also be filtered through a volcanic rock layer. The volcanic rock particles in the volcanic rock layer are no larger than 2 cm in diameter, which is used to prevent substances such as calcium sulfate and other solid impurities generated in the reaction from passing through, thereby improving the quality of the effluent. At the same time, it can also block the loss of effective components in the sulfur-based mineral-suspended material layer, calcite-wood chip layer, and growth-promoting layer to a certain extent, ensuring the stable progress of sulfur autotrophic denitrification treatment.

[0067] Among them, biochemical reaction precipitation treatment and sulfur autotrophic denitrification treatment can work together. That is, after the biochemical reaction precipitation treatment, ammonia nitrogen, COD and other substances are removed, and nitrate and nitrite are produced. Meanwhile, the sulfur autotrophic denitrification treatment efficiently converts nitrate and nitrite into nitrogen gas for discharge and removes some phosphorus. The two work together to achieve a highly efficient carbon and nitrogen removal effect. Moreover, no secondary precipitation treatment is required in the process, making the process simpler, easier to operate and highly efficient in carbon and nitrogen removal.

[0068] To improve impurity removal efficiency, the wastewater treatment process for nitrogen-containing organic wastewater can also include rapid filtration (rapid filtration III), in which the wastewater after sulfur autotrophic denitrification is passed through a filter media layer for filtration and impurity removal, further removing suspended particulate matter and impurities from the organic wastewater and improving the water quality of the treated wastewater. Specifically, the filter media layer is preferably a fine sand-grade filter media layer.

[0069] This process is suitable for treating nitrogen-containing organic wastewater, and it is even highly effective for treating organic wastewater with high nitrogen content; the concentration of ammonia nitrogen in the organic wastewater with high nitrogen content is less than or equal to 500 mg / L, and the concentration of total nitrogen is less than or equal to 1500 mg / L.

[0070] A wastewater treatment system for high-nitrogen organic wastewater.

[0071] The wastewater treatment process for the above-mentioned nitrogen-containing organic wastewater includes a biochemical reaction sedimentation tank 1 and a denitrification tank 4 connected in sequence; wherein, the biochemical reaction sedimentation tank 1 is used for biochemical reaction sedimentation treatment 1 of nitrogen-containing organic wastewater, and the denitrification tank 4 is used for sulfur autotrophic denitrification treatment 2 of nitrogen-containing organic wastewater.

[0072] The biochemical reaction sedimentation tank 1 is equipped with an aeration disc 2 at the bottom and a circulating clarifier 3 at the top. The outlet A2 of the biochemical reaction sedimentation tank is located above the circulating clarifier 3. Specifically, the inlet A1 of the biochemical reaction sedimentation tank is located on one side of the biochemical reaction sedimentation tank 1, specifically between the circulating clarifier 3 and the aeration disc 2.

[0073] Aeration discs 2 are used for aeration, providing sufficient oxygen for aerobic microorganisms in the organic wastewater to carry out aerobic reactions. The operating parameters of aeration discs 2 are designed according to the conventional influent concentration, generally maintaining the dissolved oxygen in the biological reaction sedimentation tank 1 at 3-4 mg / L. Several aeration discs 2 can be installed in the biological reaction sedimentation tank 1 as needed to ensure sufficient oxygen is provided for aerobic microorganisms in the organic wastewater to carry out aerobic reactions. Preferably, the dissolved oxygen concentration in the biological reaction sedimentation tank 1 is 3-4 mg / L.

[0074] When organic wastewater flows into the biochemical reaction sedimentation tank through inlet A1, aeration disc 2 starts to aerate, increasing the oxygen content in the wastewater. Aerobic microorganisms then begin aerobic reactions to degrade the organic matter in the wastewater, while simultaneously metabolizing it to produce nitrates, nitrites, sulfates, and phosphates.

[0075] When the surface of the organic wastewater rises to the position of the circulating clarifier 3, it flows into the circulating clarifier 3 for sedimentation and clarification. The clarified organic wastewater flows out from the outlet A2 of the biochemical reaction sedimentation tank set above the circulating clarifier 3.

[0076] The circulating clarifier 3 utilizes the air lift generated by the bottom aeration disc 2 to create circulation of the sludge-water mixture of organic wastewater within the biological reaction sedimentation tank 1, enhancing the mass transfer effect of the aerobic reaction. Simultaneously, it can achieve sludge interception, increasing the sludge concentration and improving the removal efficiency of COD and ammonia nitrogen. Inside the circulating clarifier 3, the sludge undergoes a sedimentation reaction, and the effluent flows into the outlet A2 of the biological reaction sedimentation tank after being collected by the top overflow weir. Inclined tube packing 31 can be installed inside the circulating clarifier 3 to enhance the sludge-water separation effect.

[0077] Specifically, inclined tube packing 31 can be installed on the circulating clarifier 3 near the outlet A2 of the biochemical reaction sedimentation tank to further prevent flocculent substances or impurities in the organic wastewater from flowing out of the outlet A2 of the biochemical reaction sedimentation tank and enhance the sedimentation effect.

[0078] The denitrification tank 4 is provided with a zeolite-gravel layer a, a sulfide mineral-suspended material layer b, a calcite-wood chip layer c, and a growth-promoting layer d stacked from bottom to top; the bottom of the denitrification tank 4 is provided with an inlet B1, and the top is provided with an outlet B2; the inlet B1 of the denitrification tank is connected to the biochemical reaction sedimentation tank, specifically, the inlet B1 of the denitrification tank is connected to the outlet A2 of the biochemical reaction sedimentation tank.

[0079] The zeolite-gravel layer a, the sulfide mineral-suspended material layer b, the calcite-wood chip layer c, and the growth-promoting layer d constitute the first packing unit 5; that is, the first packing unit 5 is provided in the denitrification tank 4. Preferably, a number of first packing units 5 are provided in the denitrification tank 4 from bottom to top; specifically, the number can be selected according to the actual denitrification needs.

[0080] The denitrification tank 4 may also contain a volcanic rock layer e, which is located above the first packing unit 5. The volcanic rock layer e contains volcanic rock particles with a diameter not exceeding 2 cm; the volcanic rock layer e is used for filtering and removing impurities from the wastewater. In some specific embodiments, the volcanic rock layer e is located above the first packing unit 5 for filtering and removing impurities from the wastewater after denitrification treatment by the first packing unit 5.

[0081] In other specific embodiments, the denitrification tank 4 is further provided with a second packing unit 6, which is positioned above the first packing unit 5. The second packing unit 6 includes, from bottom to top, a zeolite-gravel layer a, a sulfide mineral-suspended material layer b, a calcite-wood chip layer c, a growth-promoting layer d, and a volcanic rock layer e. The second packing unit 6 further denitrifies the wastewater after denitrification treatment by the first packing unit 5, and also performs filtration and impurity removal. Preferably, the zeolite-gravel layer a, the sulfide mineral-suspended material layer b, the calcite-wood chip layer c, and the growth-promoting layer d in the second packing unit 6 are arranged in the same manner as those in the first packing unit 5.

[0082] Specifically, the first filler unit 5 includes layers a+b+c+d, namely, zeolite-gravel layer a, sulfide mineral-suspended material layer b, calcite-wood chip layer c, and growth-promoting layer d.

[0083] In the zeolite-gravel layer a, the zeolite particle size is 2-4 cm, the gravel particle size is 2-4 cm, and the mass ratio of the zeolite to the gravel is (2-2.5):1; the height (thickness) of the zeolite-gravel layer does not exceed 15 cm.

[0084] The sulfide minerals in the sulfide mineral-suspension material layer b include sulfur and pyrite. Preferably, the sulfur particles are no larger than 1 cm, the pyrite particles are no larger than 1.5 cm, and the mass ratio of sulfur to pyrite is (1.5-2.5):1. The suspension material is preferably polyethylene hollow cylinders with a particle size of 5-7 mm. The volume ratio of sulfide minerals to suspension material is 1:3-5.

[0085] In the calcite-wood chip layer c, the calcite particle size is no greater than 2cm, the wood chip particle size is no greater than 1cm, and the volume ratio of the calcite to the wood chips is (3-3.5):1.

[0086] The growth-promoting layer d contains a growth-promoting substance, which is selected from one or more of maifanite, basalt, quartz, feldspar, and mica. Preferably, the growth-promoting substance is maifanite, that is, the growth-promoting layer d can be a maifanite layer; the particle size of the growth-promoting substance is not greater than 5 cm, and more preferably, the particle size is not greater than 2 cm.

[0087] The thickness ratio of the sulfide mineral-suspended material layer b, the calcite-wood chip layer c, and the growth-promoting layer d is (45-90):(3-8):1.

[0088] Zeolite and gravel in zeolite-gravel layer a can be mixed together; sulfide minerals in sulfide mineral-suspension material layer b can be mixed together and then dispersed on the suspension material; calcite and sawdust in calcite-wood chip layer c can be mixed together.

[0089] After flowing out of the effluent A2 of the biochemical reaction sedimentation tank, the organic wastewater enters the denitrification tank 4 through the inlet B1 of the denitrification tank. First, it enters the zeolite-gravel layer a of the first packing unit 5 to remove some ammonia nitrogen, COD, etc. Then, it enters the sulfur-based mineral-suspended material layer b, where nitrate and a small amount of nitrite are removed under the action of sulfur autotrophic microorganisms, and some phosphorus is removed by precipitation complexation. Then, the organic wastewater enters the calcite-wood chip layer c, where the substances in the packing material neutralize the acidity generated in time. Finally, it passes through the growth promotion layer d, which slowly releases growth factors to enhance the stress resistance of microorganisms.

[0090] The calcite-wood chip layer c can supplement a certain carbon source, which facilitates the partial heterotrophic denitrification reaction of the sulfur-based mineral-suspended material layer b, degrading some nitrate nitrogen. While competing with the sulfur autotrophic reaction for reaction products, it also complements the reaction and increases alkalinity slightly.

[0091] After passing through the first packing unit 5, the organic wastewater can be filtered through the volcanic rock layer e; or it can be further denitrified through the first packing unit 5 within the second packing unit 6, and then flow out through the outlet B2 of the denitrification tank set above through the volcanic rock layer e. The volcanic rock layer e can intercept debris, impurities, and solid substances such as calcium sulfate and suspended particulate matter produced after denitrification in the passing organic wastewater.

[0092] The wastewater treatment system for high-nitrogen organic wastewater may further include a rapid filter 7, which is used for rapid filtration treatment of nitrogen-containing organic wastewater. The rapid filter 7 contains a filter media layer 8. The inlet C1 of the rapid filter is located below the filter media layer 8, and the outlet C2 is located above the filter media layer 8. The inlet C1 of the rapid filter is connected to the outlet B2 of the denitrification tank. The filter media layer 8 is preferably a fine sand-graded filter media layer to further trap suspended particulate matter such as debris and impurities in the organic wastewater, ensuring the quality of the effluent. The denitrified organic wastewater flows into the rapid filter 7 through the inlet C1 below the filter media layer 8, then flows through the filter media layer 8 for impurity removal, and finally flows out through the outlet C2 above the filter media layer 8.

[0093] Preferably, the denitrification tank 4 may be equipped with a backwashing device; the backwashing device includes a first backwashing inlet pipe D1 and a first backwashing outlet pipe D2; the first backwashing inlet pipe D1 is located at the top of the denitrification tank 4, and the first backwashing outlet pipe D2 is located at the bottom of the denitrification tank 4. When the nitrate concentration in the effluent of the denitrification tank 4 increases to a certain extent or reaches a certain value, the denitrification tank 4 can be flushed by the backwashing device; specifically, before flushing, the water in the wastewater treatment system of high-nitrogen organic wastewater is drained, and then the backwashing water is introduced through the first backwashing inlet pipe D1 at the top of the denitrification tank 4 to flush the first packing unit 5 and / or the second packing unit 6 and / or the volcanic rock layer e, and then flows out through the first backwashing outlet pipe D2 at the bottom of the denitrification tank 4.

[0094] Furthermore, the backwashing device may also include a first air inlet pipe D3, which has several branch pipes. The branch pipes are arranged between the first packing unit 5 and the second packing unit 6, as well as between several first packing units 5, to perform air-water combined backwashing on the packing units, thereby improving the flushing effect on the first packing unit 5 and the second packing unit 6.

[0095] Preferably, the backwashing cycle of denitrification tank 4 is marked by a 20% increase in nitrate concentration in the effluent from outlet B2 of the denitrification tank, at which point backwashing begins; the combined air-water backwashing parameters are: air flushing intensity of 4–5 L / (m²). 2 •h), water flushing intensity is 10~15L / (m 2 ·h), first air flush for 5 minutes, then water flush for 10 minutes.

[0096] Preferably, the rapid sand filter 7 may also be equipped with a backwashing device; the backwashing device includes a second backwash inlet pipe E1, a second backwash outlet pipe E2, and a second air inlet pipe E3; the second backwash inlet pipe E1 is located at the top of the rapid sand filter 7, above the filter media layer 8; the second backwash outlet pipe E2 is located at the bottom of the rapid sand filter 7, below the filter media layer 8; the second air inlet pipe E3 is located at the bottom of the rapid sand filter 7, specifically, above the second backwash outlet pipe E2 and below the filter media layer 8.

[0097] When the turbidity of the effluent from the rapid sand filter 7 increases to a certain extent or reaches a certain value, the rapid sand filter 7 can be flushed by a backwashing device. Specifically, before flushing, the water in the wastewater treatment system for high-nitrogen organic wastewater is drained, and then the backwashing water is introduced through the second backwashing inlet pipe E1 to flush the filter media layer 8. At the same time, gas is introduced through the second air inlet pipe E3 to perform air-water combined backwashing on the filter media layer 8 and the rapid sand filter 7, and then flows out through the second backwashing outlet pipe E2.

[0098] Preferably, the backwashing cycle of the rapid sand filter 7 is marked by a 30% increase in turbidity in the effluent from outlet C2, indicating the start of backwashing. The combined air-water backwashing parameters are: air washing intensity of 2–5 L / (m²). 2 •h), water flushing intensity is 6~8L / (m 2 ·h), first air flush for 5 minutes, then water flush for 15 minutes.

[0099] Experimental Example 1

[0100] like Figure 1 A wastewater treatment system for high-nitrogen organic wastewater.

[0101] The wastewater treatment process for the above-mentioned nitrogen-containing organic wastewater includes a biochemical reaction sedimentation tank 1 and a denitrification tank 4 connected in sequence; wherein, the biochemical reaction sedimentation tank 1 is used for biochemical reaction sedimentation treatment 1 of nitrogen-containing organic wastewater, and the denitrification tank 4 is used for sulfur autotrophic denitrification treatment 2 of nitrogen-containing organic wastewater.

[0102] The biochemical reaction sedimentation tank 1 is equipped with an aeration disc 2 at the bottom and a circulating clarifier 3 at the top. The outlet A2 of the biochemical reaction sedimentation tank is located above the circulating clarifier 3. Specifically, the inlet A1 of the biochemical reaction sedimentation tank is located on one side of the biochemical reaction sedimentation tank 1, between the circulating clarifier 3 and the aeration disc 2.

[0103] When organic wastewater flows into the biochemical sedimentation tank through inlet A1, aeration disc 2 activates, increasing the oxygen content in the wastewater. The operating parameters of aeration disc 2 are designed according to the influent concentration, specifically ensuring a dissolved oxygen concentration of 3–4 mg / L in the biochemical sedimentation tank 1. Aerobic microorganisms then begin an aerobic reaction, degrading the organic matter in the wastewater and simultaneously metabolizing it to produce nitrates, sulfates, and phosphates.

[0104] When the surface of the organic wastewater rises to the position of the circulating clarifier 3, it flows into the circulating clarifier 3 for sedimentation and clarification. The clarified organic wastewater flows out from the outlet A2 of the biochemical reaction sedimentation tank set above the circulating clarifier 3.

[0105] The denitrification tank 4 is provided with a zeolite-gravel layer a, a sulfide mineral-suspended material layer b, a calcite-wood chip layer c, and a growth-promoting layer d stacked from bottom to top; the bottom of the denitrification tank 4 is provided with an inlet B1, and the top is provided with an outlet B2; the inlet B1 of the denitrification tank is connected to the biochemical reaction sedimentation tank, specifically, the inlet B1 of the denitrification tank is connected to the outlet A2 of the biochemical reaction sedimentation tank.

[0106] The zeolite-gravel layer a, the sulfide mineral-suspended material layer b, the calcite-wood chip layer c, and the growth-promoting layer d constitute the first packing unit 5; that is, a first packing unit 5 is provided in the denitrification tank 4, and a volcanic rock layer e is provided above the first packing unit 5.

[0107] In the zeolite-gravel layer a, the zeolite particle size is 2-4 cm, the gravel particle size is 2-4 cm, and the mass ratio of the zeolite to the gravel is (2-2.5):1; the height (thickness) of the zeolite-gravel layer does not exceed 15 cm.

[0108] The sulfide minerals in the sulfide mineral-suspension material layer b include sulfur and pyrite. Preferably, the sulfur particles are no larger than 1 cm, the pyrite particles are no larger than 1.5 cm, and the mass ratio of sulfur to pyrite is (1.5-2.5):1. The suspension material is preferably polyethylene hollow cylinders with a particle size of 5-7 mm. The volume ratio of sulfide minerals to suspension material is 1:3-5.

[0109] In the calcite-wood chip layer c, the calcite particle size is no greater than 2cm, the wood chip particle size is no greater than 1cm, and the volume ratio of the calcite to the wood chips is (3-3.5):1.

[0110] The growth-promoting layer d contains a growth-promoting substance, which is selected from one or more of maifanite, basalt, quartz, feldspar, and mica. Preferably, the growth-promoting substance is maifanite, that is, the growth-promoting layer d can be a maifanite layer; the particle size of the growth-promoting substance is not greater than 5 cm, and more preferably, the particle size is not greater than 2 cm.

[0111] The thickness ratio of the sulfide mineral-suspended material layer b, the calcite-wood chip layer c, and the growth-promoting layer d is (45-90):(3-8):1.

[0112] The denitrification tank 4 is equipped with a backwashing device; the backwashing device includes a first backwashing inlet pipe D1 and a first backwashing outlet pipe D2; the first backwashing inlet pipe D1 is located at the top of the denitrification tank 4, and the first backwashing outlet pipe D2 is located at the bottom of the denitrification tank 4. When the nitrate concentration in the effluent of the denitrification tank 4 increases to a certain level or reaches a certain value, the denitrification tank 4 can be flushed by the backwashing device; specifically, before flushing, the water in the wastewater treatment system for high-nitrogen organic wastewater is drained, and then the backwashing water is introduced through the first backwashing inlet pipe D1 at the top of the denitrification tank 4 to flush the first packing unit 5 and the volcanic rock layer e, and then flows out through the first backwashing outlet pipe D2 at the bottom of the denitrification tank 4.

[0113] Preferably, the backwashing cycle of denitrification tank 4 is marked by a 20% increase in nitrate concentration in the effluent from outlet B2 of the denitrification tank, at which point backwashing begins; the combined air-water backwashing parameters are: air flushing intensity of 4–5 L / (m²). 2 •h), water flushing intensity is 10~15L / (m 2 ·h), first air flush for 5 minutes, then water flush for 10 minutes.

[0114] The wastewater treatment system for high-nitrogen organic wastewater can be combined with the above-mentioned wastewater treatment process for nitrogen-containing organic wastewater to treat the organic wastewater. The treatment process is as follows:

[0115] Organic wastewater flows into the biological reaction sedimentation tank 1 through the inlet A1. It is aerated by the aeration disc 2, where aerobic microorganisms carry out an aerobic reaction, degrading the organic matter in the wastewater and causing it to precipitate. The organic wastewater then passes through the circulating clarifier 3 for sedimentation and separation, and then flows out through the outlet A2 of the biological reaction sedimentation tank. It is then introduced into the denitrification tank 4 through the inlet B1 of the denitrification tank, where it undergoes denitrification treatment through the first packing unit 5. Finally, some solid products and impurities are filtered out by the volcanic rock layer e, and the wastewater is discharged through the outlet B2 of the denitrification tank, completing the wastewater treatment of organic wastewater.

[0116] The denitrification tank 4 is equipped with a backwashing device; the backwashing device includes a first backwashing inlet pipe D1 and a first backwashing outlet pipe D2; the first backwashing inlet pipe D1 is located at the top of the denitrification tank 4, and the first backwashing outlet pipe D2 is located at the bottom of the denitrification tank 4.

[0117] When the nitrate concentration in the effluent of the denitrification tank 4 increases to a certain level or reaches a certain value, the denitrification tank 4 can be flushed by a backwashing device. Specifically, before flushing, the water in the wastewater treatment system for high-nitrogen organic wastewater is drained, and then the backwashing water is introduced through the first backwashing inlet pipe D1 at the top of the denitrification tank 4 to flush the second packing unit 6 and the first packing unit 5, and then flows out through the first backwashing outlet pipe D2 at the bottom of the denitrification tank 4. That is, the first backwashing inlet pipe D1 is set above the second packing unit 6, and the first backwashing outlet pipe D2 is set below the first packing unit 5.

[0118] Experimental Example 2

[0119] like Figure 2-3 The difference from Experimental Example 1 is that the denitrification tank 4 is equipped with several first packing units 5 and a second packing unit 6, and the system is also equipped with a rapid filter tank 7.

[0120] The plurality of first packing units 5 are stacked on top of each other, and specifically there are six first packing units 5. The first packing unit 5 is specifically as follows: Figure 4 .

[0121] A second packing unit 6 is also stacked on top of the first packing unit 5, such as... Figure 5 In the second packing unit 6, the zeolite-gravel layer a, the sulfide mineral-suspended material layer b, the calcite-wood chip layer c, and the growth-promoting layer d are arranged in the same way as in the first packing unit 5; while the volcanic rock layer e is arranged above the growth-promoting layer d, and the volcanic rock particle size in the volcanic rock layer e is no greater than 2 cm. Compared with Experimental Example 1, the denitrification effect of this experimental example is better.

[0122] Furthermore, the system also includes a rapid sand filter 7, which contains a filter media layer 8. The inlet C1 of the rapid sand filter is located below the filter media layer 8, and the outlet C2 is located above the filter media layer 8. The filter media layer 8 is preferably a fine sand graded filter media layer. Specifically, the outlet B2 of the denitrification tank is connected to the inlet C1 of the rapid sand filter. After the wastewater exits through the outlet B2 of the denitrification tank, it enters the rapid sand filter 7, where it is filtered again by the filter media layer 8 to remove solid impurities and suspended particulate matter, before exiting through the outlet C2 of the rapid sand filter, further improving the quality of the effluent.

[0123] Experimental Example 3

[0124] like Figure 6 The difference from Example 2 is that the inside of the circulating clarifier 3 can be equipped with inclined tube packing 31; the backwashing device of the denitrification tank 4 also includes the first air inlet pipe D3; at the same time, the rapid filter tank 7 is also equipped with a backwashing device, which includes the second backwashing water inlet pipe E1, the second backwashing water outlet pipe E2 and the second air inlet pipe E3.

[0125] Specifically, inclined tube packing 31 can be installed inside the circulating clarifier 3 to enhance the sludge-water separation effect. Specifically, inclined tube packing 31 is installed on the circulating clarifier 3 near the outlet A2 of the biochemical reaction sedimentation tank to further prevent flocculent substances or impurities in the organic wastewater from flowing out of the outlet A2 of the biochemical reaction sedimentation tank, thereby enhancing the sedimentation effect.

[0126] The backwashing device may also include a first air inlet pipe D3, which has several branch pipes. The branch pipes are arranged between the first packing unit 5 and the second packing unit 6, and between several first packing units 5, for performing air-water combined backwashing on the packing units. Specifically, when backwashing water is introduced through the first backwashing water inlet pipe D1 at the top of the denitrification tank 4 to backwash the denitrification tank 4, gas is also introduced through the first air inlet pipe D3 to perform gas flushing on the first packing unit 5 and the second packing unit 6.

[0127] The backwashing cycle of denitrification tank 4 is marked by a 20% increase in nitrate concentration in the effluent from outlet B2, at which point backwashing begins. The combined air-water backwashing parameters are: air flushing intensity of 4–5 L / (m²). 2 •h), water flushing intensity is 10~15L / (m 2 ·h), first air flush for 5 minutes, then water flush for 10 minutes.

[0128] The rapid sand filter 7 is also equipped with a backwashing device; the backwashing device includes a second backwashing inlet pipe E1, a second backwashing outlet pipe E2, and a second air inlet pipe E3; the second backwashing inlet pipe E1 is located at the top of the rapid sand filter 7, above the filter media layer 8; the second backwashing outlet pipe E2 is located at the bottom of the rapid sand filter 7, below the filter media layer 8; the second air inlet pipe E3 is located at the bottom of the rapid sand filter 7, specifically above the second backwashing outlet pipe E2 and below the filter media layer 8.

[0129] When the turbidity of the effluent from the rapid sand filter 7 increases to a certain extent or reaches a certain value, the rapid sand filter 7 can be flushed by a backwashing device. Specifically, before flushing, the water in the wastewater treatment system for high-nitrogen organic wastewater is drained, and then the backwashing water is introduced through the second backwashing inlet pipe E1 to flush the filter media layer 8. At the same time, gas is introduced through the second air inlet pipe E3 to perform air-water combined backwashing on the filter media layer 8 and the rapid sand filter 7, and then flows out through the second backwashing outlet pipe E2.

[0130] The backwashing cycle of rapid sand filter 7 is indicated by a 30% increase in turbidity in the effluent from outlet C2. The air-water combined backwashing parameters are: air wash intensity of 2–5 L / (m²). 2 •h), water flushing intensity is 6~8L / (m 2 ·h), first air flush for 5 minutes, then water flush for 15 minutes.

[0131] This experimental example demonstrates that the denitrification tank 4 and the rapid filter tank 7 can be flushed more conveniently and quickly, with better flushing results.

[0132] Example 1

[0133] Experimental Example 3 was used as a wastewater treatment system for high-nitrogen organic wastewater, and was combined with a wastewater treatment process for nitrogen-containing organic wastewater to treat high-nitrogen organic wastewater.

[0134] The dissolved oxygen concentration in the biochemical reaction sedimentation tank is 3 mg / L.

[0135] The first packing unit specifically includes layers a+b+c+d; in the zeolite-gravel layer a, the zeolite particle size is 2-4cm, the gravel particle size is 2-4cm, and the mass ratio of the zeolite to the gravel is 2:1; the height (thickness) of the zeolite-gravel layer a is 15cm.

[0136] The sulfide minerals in the sulfide mineral-suspension material layer b include sulfur and pyrite. Preferably, the sulfur particles are no larger than 1 cm, the pyrite particles are no larger than 1.5 cm, and the mass ratio of sulfur to pyrite is 1.5:1. The suspension material is preferably polyethylene hollow cylinders with a particle size of 5-7 mm. The stacking height (thickness) of the sulfide minerals, calcite-wood chip layer, and maifanite layer on the same bottom surface area is 15 cm, and the height (thickness) of the suspension material is 45 cm; since the sulfide minerals are dispersed in the suspension material, the height (thickness) of the sulfide mineral-suspension material layer b is 45 cm. The volume ratio of sulfide minerals to suspension material is 1:3.

[0137] In the calcite-wood chip layer c, the calcite particle size is no greater than 2cm, the wood chip particle size is no greater than 1cm, and the volume ratio of calcite to wood chips is 3:1; the height (thickness) of the calcite-wood chip layer c is 3cm.

[0138] In the growth-promoting layer d, the growth-promoting substance is maifanite, and the particle size of maifanite is no greater than 2cm; the height (thickness) of the growth-promoting layer d is 1cm.

[0139] The thickness ratio of the sulfide minerals, calcite-wood chip layer c, and growth-promoting layer d in the sulfide mineral-suspension material layer b is 15:3:1. However, the thickness ratio of the sulfide mineral-suspension material layer b, calcite-wood chip layer c, and growth-promoting layer d is 45:3:1.

[0140] The second packing unit includes the first packing unit and layer e mentioned above; in the volcanic rock layer e, the volcanic rock particle size is no greater than 2cm; the volcanic rock layer e is stacked above the first packing unit, and the height (thickness) of the volcanic rock layer e is 15cm.

[0141] Example 2

[0142] Experimental Example 3 was used as a wastewater treatment system for high-nitrogen organic wastewater, and was combined with a wastewater treatment process for nitrogen-containing organic wastewater to treat high-nitrogen organic wastewater.

[0143] The dissolved oxygen concentration in the biochemical reaction sedimentation tank is 4 mg / L.

[0144] The first packing unit specifically includes layers a+b+c+d; in the zeolite-gravel layer a, the zeolite particle size is 2-4cm, the gravel particle size is 2-4cm, and the mass ratio of the zeolite to the gravel is 2.5:1; the height (thickness) of the zeolite-gravel layer a is 12cm.

[0145] The sulfide minerals in the sulfide mineral-suspension material layer b include sulfur and pyrite. Preferably, the sulfur particles are no larger than 1 cm, the pyrite particles are no larger than 1.5 cm, and the mass ratio of sulfur to pyrite is 2.5:1. The suspension material is preferably polyethylene hollow cylinders with a particle size of 5-7 mm. The stacking height (thickness) of the sulfide minerals, calcite-wood chip layer, and growth-promoting layer on the same bottom surface area is 18 cm, and the height (thickness) of the suspension material is 90 cm; since the sulfide minerals are dispersed in the suspension material, the height (thickness) of the sulfide mineral-suspension material layer b is 90 cm. The volume ratio of sulfide minerals to suspension material is 1:5.

[0146] In the calcite-wood chip layer c, the calcite particle size is no greater than 2cm, the wood chip particle size is no greater than 1cm, and the volume ratio of calcite to wood chips is 3.5:1; the height (thickness) of the calcite-wood chip layer c is 8cm.

[0147] In the growth-promoting layer d, the growth-promoting substance is maifanite, and the particle size of maifanite is no greater than 2cm; the height (thickness) of the growth-promoting layer d is 1cm.

[0148] The thickness ratio of the sulfide minerals, calcite-wood chip layer c, and growth-promoting layer d in the sulfide mineral-suspension material layer b is 18:8:1. However, the thickness ratio of the sulfide mineral-suspension material layer b, calcite-wood chip layer c, and growth-promoting layer d is 90:8:1.

[0149] The second packing unit includes the first packing unit and layer e mentioned above; in the volcanic rock layer e, the volcanic rock particle size is no greater than 2cm; the volcanic rock layer e is stacked above the first packing unit, and the height (thickness) of the volcanic rock layer e is 18cm.

[0150] Example 3

[0151] Experimental Example 3 was used as a wastewater treatment system for high-nitrogen organic wastewater, and was combined with a wastewater treatment process for nitrogen-containing organic wastewater to treat high-nitrogen organic wastewater.

[0152] The dissolved oxygen concentration in the biochemical reaction sedimentation tank is 3.5 mg / L.

[0153] The first packing unit specifically includes layers a+b+c+d; in the zeolite-gravel layer a, the zeolite particle size is 2-4cm, the gravel particle size is 2-4cm, and the mass ratio of the zeolite to the gravel is 2.3:1; the height (thickness) of the zeolite-gravel layer a is 14cm.

[0154] The sulfide minerals in the sulfide mineral-suspension material layer b include sulfur and pyrite. Preferably, the sulfur particles are no larger than 1 cm, the pyrite particles are no larger than 1.5 cm, and the mass ratio of sulfur to pyrite is 2:1. The suspension material is preferably polyethylene hollow cylinders with a particle size of 5-7 mm. The stacking height of the sulfide minerals, calcite-wood chip layer, and growth-promoting layer on the same bottom surface area is 16 cm, and the height (thickness) of the suspension material is 64 cm; since the sulfide minerals are dispersed in the suspension material, the height (thickness) of the sulfide mineral-suspension material layer b is 64 cm. The volume ratio of sulfide minerals to suspension material is 4:1.

[0155] In the calcite-wood chip layer c, the calcite particle size is no greater than 2cm, the wood chip particle size is no greater than 1cm, and the volume ratio of calcite to wood chips is 3.2:1; the height (thickness) of the calcite-wood chip layer c is 6cm.

[0156] In the growth-promoting layer d, the growth-promoting substance is maifanite, and the particle size of maifanite is no greater than 2cm; the height (thickness) of the growth-promoting layer d is 1cm.

[0157] The thickness ratio of the sulfide minerals, calcite-wood chip layer c, and growth-promoting layer d in the sulfide mineral-suspension material layer b is 16:6:1. However, the thickness ratio of the sulfide mineral-suspension material layer b, calcite-wood chip layer c, and growth-promoting layer d is 64:6:1.

[0158] The second packing unit includes the first packing unit and layer e mentioned above; in the volcanic rock layer e, the volcanic rock particle size is no greater than 2cm; the volcanic rock layer e is stacked above the first packing unit, and the height (thickness) of the volcanic rock layer e is 18cm.

[0159] High-nitrogen organic wastewater from the same source was treated using the system described in this example. The treated effluent was then tested, and the test results are shown in Table 1 below.

[0160] Test items:

[0161] COD: Potassium dichromate method;

[0162] Total nitrogen: Alkaline potassium persulfate ultraviolet spectrophotometry (HJ 636-2012);

[0163] Ammonia nitrogen: Nessler colorimetric method;

[0164] Suspended particulate matter: gravimetric method.

[0165] The specific steps for the gravimetric method are as follows:

[0166] (1) Using toothless flat-tipped tweezers, pick up a 0.45μm microporous filter membrane and place it in a weighing bottle. Transfer it to a forced-air drying oven and dry it at 103-105℃ for one hour. Then remove it and place it in a desiccator to cool to room temperature. Weigh it. Repeat the drying, cooling, and weighing process until the difference between two weighings is ≤0.2mg (constant weight). Record the mass of the filter membrane and the weighing bottle as m1 (g).

[0167] (2) Place the constant-weighted filter membrane correctly on the filter membrane tray of the filter membrane filter, cover it with the matching Buchner hole, and secure it with clips. Wet the filter membrane with distilled water and continuously absorb the filter.

[0168] (3) Accurately measure 100 mL of a well-mixed water sample and filter it by suction. Then wash it three times with 10 mL of distilled water each time and continue to filter to remove trace amounts of water.

[0169] (4) After stopping the suction filtration, carefully remove the filter membrane and place it in the original weighing bottle. Transfer it to a forced-air drying oven and dry it at 103-105℃ until it reaches constant weight. Weigh it, and record the mass of the suspended solids, filter membrane and weighing bottle as m2 (g).

[0170] Calculation method:

[0171] SS=(m1-m2)×10 6 / V(mg / L).

[0172] Table 1. Test results of organic wastewater treated by the system in the embodiment.

[0173]

[0174] Wherein, A1 is the inlet of the biochemical reaction sedimentation tank, B1 is the inlet of the denitrification tank, and B2 is the outlet of the denitrification tank.

[0175] As shown in Table 1, Examples 1-3 all achieved good decarbonization and denitrification effects, specifically, COD value ≤ 60 mg / L, ammonia nitrogen value ≤ 5.5 mg / L, total nitrogen value ≤ 42 mg / L, and suspended particulate matter ≤ 20 mg / L. Furthermore, the appropriate thickness of each layer of the packing material effectively balances the decarbonization and denitrification effect with economic benefits, achieving the optimal solution for both.

[0176] Specifically, based on Example 3, a comparative example is set up. The differences between the comparative example and Example 3 are shown in Table 2 below.

[0177] Table 2 shows the differences between the comparative example and Example 3.

[0178]

[0179]

[0180] High-nitrogen organic wastewater from the same source was treated using the same system as in the comparative example. The treated organic wastewater was then tested, and the test results are shown in Table 3 below.

[0181] Table 3 shows the test results of the organic wastewater after system treatment in the comparative example.

[0182]

[0183]

[0184] Wherein, A1 is the inlet of the biochemical reaction sedimentation tank, B1 is the inlet of the denitrification tank, and B2 is the outlet of the denitrification tank.

[0185] As can be seen from Tables 2 and 4 above, comparing Comparative Example 1 with Example 3, the addition of suspended material enhances the removal effect of total nitrogen.

[0186] Comparing Comparative Examples 2-3 with Example 3, it is evident that sulfide minerals have a significant impact on the removal of total nitrogen, with sulfur playing a decisive role. Insufficient sulfur content and proportion result in poor removal of total nitrogen. Specifically, a certain thickness and mass ratio of sulfur to pyrite are necessary for effective removal of total nitrogen. While increasing the sulfur thickness and proportion can improve removal efficiency, the improvement slows down and is not economical. Comparing Comparative Examples 4-5 with Example 3, it is clear that calcite plays a positive role in denitrification within the calcite-wood chip layer. This is primarily because calcite neutralizes acidic substances produced during sulfur autotrophic reactions, preventing inhibition of denitrifying microorganisms. Without calcite, this effect is not achieved, resulting in significantly poor decarbonization and denitrification. Increasing the calcite content and proportion can improve total nitrogen removal to a certain extent, but the improvement slows down and is not economical.

[0187] Comparing Comparative Examples 6-9 with Example 3, it can be seen that the optimal decarbonization and denitrification effect can be achieved when the thickness ratio of the sulfide mineral-suspended material layer, calcite-wood chip layer, and maifanite layer is (45-90):(3-8):1. This also combines economic cost-effectiveness and achieves the best solution. If the thickness of any one of the layers is increased, although the decarbonization and denitrification effect can be improved to a certain extent, the economic cost will also increase, and the improvement in the decarbonization and denitrification effect is not significant, which does not meet the optimal economic benefits.

[0188] Comparing Comparative Examples 10-11 with Example 3, it can be seen that dissolved oxygen in the biochemical reaction sedimentation tank also affects the final decarbonization and denitrification effect. Specifically, if the dissolved oxygen in the biochemical reaction sedimentation tank is too high or too low, it is impossible to effectively remove ammonia nitrogen and other nitrogen by biochemical reaction sedimentation treatment, thereby producing nitrate and nitrite, resulting in poor effect of subsequent sulfur autotrophic denitrification treatment. That is, biochemical reaction sedimentation treatment and sulfur autotrophic denitrification treatment need to be combined to achieve the best decarbonization and denitrification effect.

[0189] The above description is merely an example to further illustrate the technical content of the present invention, so as to facilitate the reader's understanding. However, it does not mean that the implementation of the present invention is limited to this. Any technical extension or re-creation made in accordance with the present invention is protected by the present invention.

Claims

1. A treatment process for nitrogen-containing organic wastewater, characterized in that: The nitrogen-containing organic wastewater is sequentially subjected to biochemical reaction precipitation treatment and sulfur autotrophic denitrification treatment. The sulfur autotrophic denitrification treatment includes passing the wastewater after biochemical reaction precipitation treatment sequentially through a zeolite-gravel layer, a sulfur-based mineral-suspended material layer, a calcite-wood chip layer, and a growth-promoting layer for denitrification treatment; the thickness ratio of the sulfur-based mineral-suspended material layer, the calcite-wood chip layer, and the growth-promoting layer is (45-90):(3-8):1; The sulfide minerals in the sulfide mineral-suspension material layer include sulfur and pyrite; the mass ratio of sulfur to pyrite in the sulfide minerals is (1.5-2.5):1; the volume ratio of calcite to wood chips in the calcite-wood chip layer is (3-3.5):

1. The growth-promoting layer contains maifanite.

2. The treatment process for nitrogen-containing organic wastewater according to claim 1, characterized in that, In the sulfide mineral-suspension material layer, the suspension material is a polyethylene hollow column, and the volume ratio of sulfide minerals to suspension material is 1:(3-5); in the zeolite-gravel layer, the mass ratio of zeolite to gravel is (2-2.5):

1.

3. The treatment process for nitrogen-containing organic wastewater according to claim 1, characterized in that, The zeolite-gravel layer, sulfide mineral-suspended material layer, calcite-wood chip layer, and growth-promoting layer constitute the first packing unit; the wastewater flows through the first packing unit for denitrification treatment, and then is filtered through the volcanic rock layer.

4. A treatment system for nitrogen-containing organic wastewater, characterized in that, It includes a biochemical reaction sedimentation tank and a denitrification tank connected in sequence; the biochemical reaction sedimentation tank is used for biochemical reaction sedimentation treatment of nitrogen-containing organic wastewater as described in claim 1, and the denitrification tank is used for sulfur autotrophic denitrification treatment of nitrogen-containing organic wastewater as described in claim 1. The denitrification tank contains, from bottom to top, a zeolite-gravel layer, a sulfide mineral-suspended material layer, a calcite-wood chip layer, and a growth-promoting layer; the bottom of the denitrification tank has an inlet, and the top has an outlet; the inlet of the denitrification tank is connected to a biochemical reaction sedimentation tank.

5. The treatment system for nitrogen-containing organic wastewater according to claim 4, characterized in that, The zeolite-gravel layer, sulfide mineral-suspended material layer, calcite-wood chip layer, and growth-promoting layer constitute the first packing unit; the denitrification tank is also provided with a volcanic rock layer, which is located above the first packing unit.

6. The treatment system for nitrogen-containing organic wastewater according to claim 4, characterized in that, The zeolite-gravel layer, the sulfide mineral-suspended material layer, the calcite-wood chip layer, and the growth-promoting layer constitute the first packing unit; the denitrification tank is also provided with a second packing unit, which is located above the first packing unit; the second packing unit includes, from bottom to top, the zeolite-gravel layer, the sulfide mineral-suspended material layer, the calcite-wood chip layer, the growth-promoting layer, and the volcanic rock layer.

7. The treatment system for nitrogen-containing organic wastewater according to claim 4, characterized in that, The biochemical reaction sedimentation tank is equipped with an aeration disc at the bottom and a circulating clarifier at the top. The outlet of the biochemical reaction sedimentation tank is located above the circulating clarifier. The outlet of the biochemical reaction sedimentation tank is connected to the inlet of the denitrification tank.

8. The treatment system for nitrogen-containing organic wastewater according to claim 7, characterized in that, The denitrification tank is equipped with a backwashing device; the backwashing device includes a first backwashing inlet pipe and a first backwashing outlet pipe; the first backwashing inlet pipe is located at the top of the denitrification tank, and the first backwashing outlet pipe is located at the bottom of the denitrification tank.

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