A system and method for inhibiting total nitrogen increase in a tobacco sheet sewage aerobic tank during restart

Abstract

The present application belongs to the technical field of reconstituted tobacco production wastewater treatment, and particularly relates to a system and method for inhibiting total nitrogen increase in a tobacco sheet wastewater aerobic tank during restart. The system for inhibiting total nitrogen increase in a tobacco sheet wastewater aerobic tank during restart comprises a pretreatment mechanism, an anaerobic treatment mechanism, an aerobic treatment mechanism, a deep treatment mechanism, and a sludge treatment mechanism. The system is maintained in a shutdown phase to inhibit total nitrogen increase in the aerobic treatment mechanism. The pretreatment mechanism comprises a water collection tank, a drum filter, a primary sedimentation tank, and a regulating tank connected in sequence by a liquid phase flow pipeline. The present application also provides a method for inhibiting total nitrogen increase in a tobacco sheet wastewater aerobic tank using the system. The present application inhibits total nitrogen increase in the aerobic tank by sequentially implementing an operation mode of "shutdown micro-exposure period - muffled exposure activation period - cycle consolidation period - normal operation period", thereby prolonging the service life of the system.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology in reconstituted tobacco production, specifically relating to a system and method for inhibiting the rise of total nitrogen in the aerobic tank of tobacco sheet wastewater after restarting. Background Technology

[0002] After the tobacco sheet production ceased, the tobacco sheet wastewater treatment system also entered a shutdown maintenance state due to reduced influent volume. During this process, the routine maintenance method for the aerobic system was intermittent aeration, mainly 1 hour of aeration per 12 hours, with an aeration volume of 15-20 m³ / h. During each aeration period, 5 kg of monoammonium phosphate and 50 liters of tobacco plant extract with a COD of approximately 500,000 mg / L were added. In addition, a certain amount of carbon source and nutrients (N / P fertilizer) were added during routine maintenance to keep the entire aerobic system in an aerobic state.

[0003] Due to issues such as partial deflocculation of the aerobic sludge in the aerobic system, partial sludge aging (caused by prolonged nutrient deficiency of microorganisms, i.e., an imbalance between nutrients and microbial biomass, preventing normal microbial growth), loss of activated sludge with water, and poor activity of sludge microorganisms (the biological community in activated sludge, including bacteria, protozoa, rotifers, and nematodes), the aerobic system for tobacco sheet wastewater treatment experienced an increase in total nitrogen in the effluent after the tobacco sheet production line resumed operation and restarted. This resulted in levels exceeding the pre-shutdown standard. It was necessary to run the system for a week prior to the shutdown for the total nitrogen level to return to normal. During normal production, the influent total nitrogen was 60-80 mg / L, while before the shutdown, the effluent total nitrogen was maintained at 25-35 mg / L. Environmental standards exceeding 50 mg / L are considered substandard. After restarting, the total nitrogen level remained high at 40-60 mg / L for about a week before returning to the normal operating level of 25-35 mg / L. This situation not only increased production costs but also caused some damage to the equipment.

[0004] Therefore, it is necessary to find a method to suppress the rise in total nitrogen in the aerobic system for tobacco leaf wastewater after shutdown and restart, so as to ensure that the total nitrogen in the wastewater effluent consistently meets the discharge standards. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a system and method for suppressing the rise of total nitrogen in the aerobic tank of tobacco sheet wastewater during restart. By sequentially performing the operation mode of "shutdown micro-aeration period - sultry aeration activation period - circulation consolidation period - normal operation period", the rise of total nitrogen in the aerobic tank is suppressed, thereby extending the service life of the system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A system for suppressing the rise in total nitrogen during the restart of an aerobic tank for tobacco flake wastewater includes a pretreatment unit, an anaerobic treatment unit, an aerobic treatment unit, an advanced treatment unit, and a sludge treatment unit; the system suppresses the rise in total nitrogen in the aerobic treatment unit by performing maintenance during shutdown phases.

[0008] The pretreatment mechanism includes a water collection tank, a rotary drum filter, a primary sedimentation tank, and an equalization tank, which are connected in sequence through a liquid phase flow pipeline.

[0009] The anaerobic treatment unit includes a hydrolysis acidification tank and an anaerobic reactor (IC) connected in sequence through a liquid phase flow pipeline;

[0010] The wastewater discharge end of the equalization tank is connected to the inlet end of the hydrolysis acidification tank through the first outlet pipe;

[0011] The aerobic treatment mechanism includes an aerobic treatment tank and a secondary sedimentation tank that are connected in sequence through a liquid phase flow pipeline.

[0012] The wastewater discharge end of the anaerobic reactor (IC) is connected to the inlet end of the aerobic treatment tank through a second outlet pipe;

[0013] The advanced treatment mechanism includes a primary reaction tank, a tertiary sedimentation tank, a secondary reaction tank, and a quaternary sedimentation tank, which are connected in sequence through liquid phase flow pipelines.

[0014] The wastewater discharge end of the secondary sedimentation tank is connected to the inlet end of the primary reaction tank through a third outlet pipe.

[0015] The sludge treatment facility includes a sludge thickening tank and a sludge balancing tank that are connected in sequence by pipelines.

[0016] Furthermore, a first shut-off valve is provided on the first outlet pipe.

[0017] Furthermore, the fourth sedimentation tank is equipped with an outlet, and the treated wastewater is discharged in compliance with standards through the outlet pipe.

[0018] Furthermore, a second shut-off valve is installed on the third outlet pipe.

[0019] Furthermore, a grid is installed at the top of the water collection tank; the model of the rotary drum filter is ZL350X600.

[0020] Furthermore, the primary and secondary reaction tanks are also equipped with additive inlet terminals, where additives include polyaluminum ferric sulfate, composite iron salt agents, and PAM flocculant.

[0021] In a further preferred embodiment, the secondary reaction tank is also equipped with a pH adjustment inlet, which uses liquid alkaline agents to adjust the pH so that the wastewater pH is adjusted to 6-9 before being discharged in compliance with standards.

[0022] Furthermore, the primary sedimentation tank, secondary sedimentation tank, tertiary sedimentation tank, and quaternary sedimentation tank are all equipped with sludge discharge pipes, which are connected to the inlet end of the sludge thickening tank.

[0023] Furthermore, the outlet of the equalization tank is connected to the inlet of the aerobic treatment tank via a first bypass pipe, which serves as a pipeline for the equalization tank to "overtake" the process route.

[0024] In a further preferred embodiment, a third shut-off valve is provided on the first bypass pipe.

[0025] Furthermore, the air inlet of the aerobic treatment tank is connected to an air inlet pipe, and a blower is installed on the air inlet pipe. Oxygen is introduced into the aerobic treatment tank through the blower to achieve aeration.

[0026] Furthermore, the outlet of the secondary sedimentation tank is connected to the collection tank via a second bypass pipe.

[0027] In a further preferred embodiment, a fourth shut-off valve is provided on the second bypass pipe.

[0028] Furthermore, the outlet end of the anaerobic reactor (IC) is also equipped with a first return pipe, which is connected to the inlet end of the hydrolysis acidification tank. Through the first return pipe, part of the wastewater treated by the anaerobic reactor (IC) is returned to the hydrolysis acidification tank for secondary hydrolysis acidification treatment, so as to improve the degree of hydrolysis acidification treatment.

[0029] Furthermore, the outlet of the secondary sedimentation tank is equipped with a second return pipe, which is connected to the inlet of the aerobic treatment tank. Through the second return pipe, part of the wastewater treated by the secondary sedimentation tank is returned to the aerobic treatment tank for secondary aerobic treatment to improve the degree of aerobic treatment.

[0030] Furthermore, based on a general inventive concept, the present invention also provides a method for suppressing the rise of total nitrogen in an aerobic tank of tobacco flake wastewater using the aforementioned system, comprising the following steps:

[0031] 1) Shutdown and micro-aeration period: After the system stops, the aerobic treatment tank enters the shutdown and micro-aeration period. During this period, a certain amount of carbon source and nutrients are added to the aerobic treatment tank every day. At the same time, intermittent or micro-aeration process is used to intermittently aerate the aerobic treatment tank, so that the aerobic treatment tank is in a micro-anaerobic state and the aerobic activated sludge is in a "semi-dormant" state.

[0032] 2) Activation period: The aerobic treatment tank adopts continuous aeration and the activated sludge in the aerobic treatment tank is activated by 1-2 days of continuous aeration.

[0033] 3) Consolidation period: The sewage in the collection tank passes through the rotary drum filter and the primary sedimentation tank in sequence and enters the equalization tank. At this time, the first shut-off valve on the first outlet pipe is closed and the third shut-off valve on the first bypass pipe is opened. The outlet of the equalization tank is connected to the inlet of the aerobic treatment tank through the first bypass pipe, forming a "beyond" pipeline that does not pass through the anaerobic reactor (IC), and the sewage in the equalization tank is directly introduced into the aerobic treatment tank.

[0034] Then, the sewage containing the mud-water mixture in the aerobic treatment tank overflows into the secondary sedimentation tank. At this time, the fourth shut-off valve on the second bypass pipe is opened, and the supernatant in the secondary sedimentation tank flows into the collection tank through the second bypass pipe in an overflow manner, which is the "circulation" process.

[0035] 4) Normal operation period: After the circulation consolidation period is completed, close the third shut-off valve on the first bypass pipe, open the first shut-off valve on the first outlet pipe, open the second shut-off valve on the third outlet pipe, and enter the normal operation period.

[0036] Subsequently, by repeating steps 1), 2), 3), and 4), the rise in total nitrogen in the aerobic treatment tank can be suppressed.

[0037] Specifically, the carbon source in step 1) is starch, white sugar, or tobacco plant extract, and the nutrients are nitrogen fertilizer and / or phosphorus fertilizer.

[0038] Specifically, in step 1), the carbon source and nutrients are added as follows: during the micro-aeration period when the aerobic treatment tank is shut down, a fixed amount of white sugar, monoammonium phosphate, and tobacco plant extract (COD of about 500,000 mg / L) are added daily as carbon sources (mainly carbon-containing compounds, which provide carbon skeletons for microbial growth and energy required for cell life activities) and other nutrients.

[0039] Specifically, in step 1), the intermittent or micro-aeration process involves intermittent aeration for 1 hour per day (i.e., aeration for 1 hour every 24 hours, with an aeration volume of 10-15 m³ / h). 3 Dissolved oxygen was maintained at 0.1-0.6 mg / L per hour, keeping the aerobic treatment tank in a slightly anaerobic state.

[0040] Specifically, in step 2), the activated sludge in the aerobic treatment tank is aerated by adjusting the blower frequency and using the blower to blow air into the aerobic treatment tank through the air inlet pipe, so that the dissolved oxygen in the aerobic treatment tank is controlled at 1-3 mg / L. The color of the sludge in the aerobic treatment tank gradually changes from black to light gray and then to yellowish brown, thus realizing the "activation" of the activated sludge in the aerobic treatment tank.

[0041] Specifically, in step 3), when the wastewater in the equalization tank is directly introduced into the aerobic treatment tank, the COD is 1500-2000 mg / L, and the excess is 50-80 mg / L.3 / h.

[0042] Specifically, in step 3), while the supernatant in the secondary sedimentation tank overflows into the collection tank through the second bypass pipe, a portion of aged sludge is discharged from the bottom of the secondary sedimentation tank, with a discharge volume of 1-5 m³. 3 / h.

[0043] Specifically, in step 3), during the circulation consolidation period, the aerobic treatment tank is continuously aerated. By adjusting the blower frequency, the blower is used to blow air into the aerobic treatment tank through the air inlet pipe, so that the dissolved oxygen in the aerobic treatment tank is controlled at 1-3 mg / L. The circulation is generally carried out for 1-2 days. During this period, nutrients (N / P fertilizer) and carbon sources (sugar, starch) are added at the same time, and the secondary sedimentation tank is used to remove sludge, so that the activated sludge in the aerobic treatment tank enters the "normal stable state".

[0044] Specifically, in step 4), during normal operation, a certain amount of carbon source (including starch, sugar, and tobacco plant extract) and nutrients (N / P fertilizer) are added to the aerobic treatment tank every day.

[0045] Specifically, in step 4), the normal operating mode is as follows:

[0046] Wastewater from tobacco sheet production flows through pipelines and undergoes preliminary filtration at the top of the collection tank via a screen. It then enters the collection tank and, via pipelines, proceeds to a rotary drum filter. After further filtration in the rotary drum filter, it enters the primary sedimentation tank. Utilizing gravity settling, settleable and floating matter in the wastewater is flocculated into larger particles, which then settle to the bottom of the tank for preliminary sedimentation. The wastewater then flows through pipelines to an equalization tank to regulate its flow rate and quality. Finally, it flows through the first effluent pipe into a hydrolysis acidification tank. Here, enzymes released by hydrolytic and acid-producing bacteria promote biocatalytic reactions of large molecules in the water that are difficult to biodegrade, trapping and gradually converting non-dissolved organic matter into dissolved organic matter. The wastewater then flows through pipelines to an anaerobic reactor (IC). Under anaerobic conditions, microorganisms decompose the organic matter into biogas through fermentation. The wastewater, along with organic fertilizer, enters the aerobic treatment tank through the second effluent pipe. In the aerobic environment, the organic matter is decomposed into inorganic substances such as CO2 and H2O through the aerobic metabolism of microorganisms, releasing energy and emitting oxygen. Then, the wastewater enters the secondary sedimentation tank to achieve sludge-water separation. It then enters the primary reaction tank through pipelines, where flocculants, pH adjusters, and other chemical agents are added. Through biochemical treatment, TN and TP in the wastewater are removed. The wastewater then enters the tertiary sedimentation tank through pipelines, where small particles suspended in the water are removed through gravity sedimentation. The wastewater then enters the secondary reaction tank through pipelines for further desalination, hardness reduction, and removal of toxic substances, pathogens, and bacteria. Finally, it enters the quaternary sedimentation tank, where suspended particles are further settled and the organic load in the water is further removed, building upon the work done in the tertiary sedimentation tank and the secondary reaction tank.

[0047] Specifically, in step 4), the sediment in the primary sedimentation tank, secondary sedimentation tank, tertiary sedimentation tank, and quaternary sedimentation tank enters the sludge thickening tank through the sludge discharge pipe for preliminary thickening, and then enters the sludge balancing tank through the pipeline for balancing and buffering. Finally, the treated sludge is transported off-site.

[0048] Compared with the prior art, the beneficial effects of the present invention are:

[0049] The system and method described in this invention suppress the rise of total nitrogen in the aerobic tank by sequentially performing an operation mode of "shutdown micro-aeration period - smoldering aeration activation period - circulation consolidation period - normal operation period", thereby extending the service life of the system.

[0050] After the implementation of this invention, compared with commonly used technical means, it avoids the input of a large amount of carbon source and reduces aeration energy consumption; the activated sludge in the aerobic treatment tank successively goes through the "semi-dormant state", "activated state" and "normal stable state", avoiding problems such as aerobic sludge aging and sludge deflocculation, and seamlessly connects to normal operation, suppressing the problem of total nitrogen rise during the shutdown and restart of the tobacco sheet wastewater aerobic treatment tank. Attached Figure Description

[0051] Figure 1 This is a flowchart of the system described in Example 1 for suppressing the increase in total nitrogen in the aerobic tank of tobacco flake wastewater upon restart;

[0052] The components are as follows: 11. Collection tank; 12. Rotary drum filter; 13. Primary sedimentation tank; 14. Equalization tank; 141. First shut-off valve; 142. First bypass pipe; 143. Third shut-off valve; 21. Hydrolysis acidification tank; 22. Anaerobic reactor (IC); 221. First return pipe; 31. Aerobic treatment tank; 311. Blower; 32. Secondary sedimentation tank; 321. Secondary return pipe; 322. Secondary shut-off valve; 323. Secondary bypass pipe; 41. Primary reaction tank; 42. Tertiary sedimentation tank; 43. Secondary reaction tank; 44. Quaternary sedimentation tank; 51. Sludge thickening tank; 52. Sludge balancing tank. Detailed Implementation

[0053] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0054] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0055] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0056] Example 1

[0057] like Figure 1 As shown, a system for suppressing the rise in total nitrogen during the restart of an aerobic tank for tobacco flake wastewater includes a pretreatment unit, an anaerobic treatment unit, an aerobic treatment unit, an advanced treatment unit, and a sludge treatment unit; the system suppresses the rise in total nitrogen in the aerobic treatment unit by performing maintenance during shutdown phases.

[0058] The pretreatment mechanism includes a water collection tank 11, a rotary drum filter 12, a primary sedimentation tank 13, and an equalization tank 14, which are connected in sequence through a liquid phase flow pipeline.

[0059] The anaerobic treatment unit includes a hydrolysis acidification tank 21 and an anaerobic reactor (IC) 22 connected in sequence through a liquid phase flow pipeline;

[0060] The wastewater discharge end of the equalization tank 14 is connected to the inlet end of the hydrolysis acidification tank 21 through the first outlet pipe, and the first outlet pipe is equipped with a first shut-off valve 141.

[0061] The aerobic treatment mechanism includes an aerobic treatment tank 31 and a secondary sedimentation tank 32 that are connected in sequence through a liquid phase flow pipeline.

[0062] The wastewater discharge end of the anaerobic reactor (IC) 22 is connected to the inlet end of the aerobic treatment tank 31 through the second outlet pipe;

[0063] The advanced treatment mechanism includes a primary reaction tank 41, a tertiary sedimentation tank 42, a secondary reaction tank 43, and a quaternary sedimentation tank 44, which are connected in sequence through a liquid phase flow pipeline; the quaternary sedimentation tank 44 is provided with an outlet end, and the treated wastewater is discharged in compliance with standards through an outlet pipe.

[0064] The wastewater discharge end of the secondary sedimentation tank 32 is connected to the inlet end of the primary reaction tank 41 through the third outlet pipe, and the third outlet pipe is equipped with a second shut-off valve 322.

[0065] The top of the water collection tank 11 is equipped with a grid; the model of the rotary drum filter 12 is ZL350X600.

[0066] The primary sedimentation tank 13 mainly utilizes the principle of gravity sedimentation to flocculate settleable and floating matter in wastewater into larger particles, which are then settled to the bottom of the tank to purify the water and enhance the solid-liquid separation effect. The primary sedimentation tank 13 can remove settleable and floating matter from wastewater. After primary sedimentation, approximately 50% of settleable matter, grease, and floating matter, and 20% of BOD can be removed from the wastewater. To a certain extent, the primary sedimentation tank 13 can homogenize the water quality and mitigate the impact of water quality changes on the subsequent biological system.

[0067] The main function of the equalization tank 14 is to regulate water flow and water quality. By introducing air into it, the water quality can be mixed and regulated. At the same time, it provides a buffer against organic load, prevents drastic changes in the biological treatment system, and controls the pH value to reduce the amount of chemicals used in the neutralization process.

[0068] The main function of the hydrolysis acidification tank 21 is to promote the biocatalytic reaction of large molecules in water that are difficult to biodegrade through the enzymes released by hydrolytic bacteria and acid-producing bacteria. Specifically, this is manifested as chain breaking and water solubility. The microorganisms use water-soluble substrates to complete intracellular biochemical reactions and at the same time discharge various organic acids.

[0069] The hydrolysis acidification process can retain non-dissolved organic matter in wastewater and gradually transform it into dissolved organic matter. Some macromolecules that are difficult to biodegrade are transformed into small molecules that are easy to degrade, such as organic acids, thereby greatly improving the biodegradability and degradation rate of wastewater, which is beneficial for subsequent aerobic biological treatment.

[0070] The hydrolysis acidification process can change the form and properties of organic matter in wastewater, which is beneficial to subsequent aerobic treatment. Therefore, the hydrolysis acidification tank 21 can change the biodegradability of the original wastewater, thereby reducing the reaction time and energy consumption of treatment. At the same time, the hydrolysis acidification process can also degrade solid organic matter and reduce the amount of sludge.

[0071] The main function of the anaerobic reactor (IC) 22 is to effectively treat various organic wastes, such as pesticide waste, food waste, and sludge. Under anaerobic conditions, microorganisms decompose organic matter into biogas and organic fertilizer through fermentation. This not only achieves energy recovery but also reduces greenhouse gas emissions, realizing the harmless treatment and resource utilization of waste, reducing environmental pollution, and improving resource utilization efficiency. The anaerobic reactor (IC) 22 used in this application is model IC-2500.

[0072] The aerobic treatment tank 31 contains activated sludge for microbial growth and metabolism. Its main function is to introduce oxygen through stirring and aeration. In an aerobic environment, through the aerobic metabolism of microorganisms, organic matter is decomposed into inorganic substances such as CO2 and H2O, releasing energy and emitting oxygen.

[0073] The primary function of the secondary sedimentation tank 32 is sludge-water separation. It clarifies the mixed liquor after biological treatment and effectively concentrates the separated sludge. The secondary sedimentation tank 32 can also provide a certain concentration of return sludge or treated water to the biological treatment facility, which is essential for maintaining the normal operation of the activated sludge system.

[0074] The primary function of the primary reaction tank 41 is to remove TN and TP from wastewater by adding flocculants, pH adjusters and other chemical agents and then treating the wastewater using biochemical methods, including AO / AAO / SBR processes.

[0075] The primary function of the tertiary sedimentation tank 42 is to remove small particles suspended in water through gravity sedimentation. When wastewater enters the tank, the suspended particles gradually sink to the bottom under the influence of gravity. After three stages of sedimentation, most of the suspended particles in the water are removed, and the water quality is significantly improved. In addition to removing suspended particles, the tertiary sedimentation tank 42 also removes some of the organic load in the water. When treating high-concentration organic wastewater, the tertiary sedimentation tank can play a better role in effectively reducing the organic load and thus improving the efficiency of subsequent treatment processes.

[0076] The secondary reaction tank 43 is a deep treatment tank. Its main function is to further desalinate, reduce hardness, and remove toxic substances, pathogens, and bacteria. At the same time, the secondary reaction tank 43 also adjusts the pH of the wastewater to meet the standards by adding pH adjusters.

[0077] The main function of the fourth sedimentation tank 44 is to further settle suspended particles in the wastewater after passing through the secondary reaction tank 43, and further remove organic load in the water, based on the third sedimentation tank 42.

[0078] The primary reaction tank 41 and the secondary reaction tank 43 are also equipped with additive inlet terminals, which include polyaluminum ferric sulfate, composite iron salt agents and PAM flocculant; in addition, the secondary reaction tank 43 is also equipped with a pH adjustment inlet terminal, which adjusts the pH of the wastewater to 6-9 by using liquid alkali agents to meet the discharge standards.

[0079] The sludge treatment facility includes a sludge thickening tank 51 and a sludge balancing tank 52 connected in sequence by pipelines.

[0080] The main function of the sludge thickening tank 51 is to thicken the sludge. By collecting the sludge obtained from the sedimentation in the primary sedimentation tank 13, secondary sedimentation tank 32, tertiary sedimentation tank 42 and quaternary sedimentation tank 44, the water in the sludge is separated by sedimentation, compression or centrifugation, thereby reducing the sludge volume and increasing the concentration, thus improving the coarse particle efficiency.

[0081] The main function of the sludge balancing tank 52 is to balance and buffer between the sludge thickening tank 51 and the subsequent dewatering equipment. It can make the solid content of the thickened sludge relatively uniform and ensure that the sludge feed rate and concentration of the dewatering machine are balanced.

[0082] Primary sedimentation tank 13, secondary sedimentation tank 32, tertiary sedimentation tank 42 and quaternary sedimentation tank 44 are all equipped with sludge discharge pipes, which are connected to the inlet end of sludge thickening tank 51.

[0083] Furthermore, the outlet of the equalization tank 14 is also connected to the inlet of the aerobic treatment tank 31 through the first bypass pipe 142. Here, the first bypass pipe 142 serves as a pipeline for the equalization tank 14 to "overtake" the process route; a third shut-off valve 143 is provided on the first bypass pipe 142.

[0084] The air inlet of the aerobic treatment tank 31 is connected to an air inlet pipe, and a blower 311 is installed on the air inlet pipe. Oxygen is introduced into the aerobic treatment tank 31 through the blower 311 to achieve aeration.

[0085] The outlet of the secondary sedimentation tank 32 is connected to the water collection tank 11 through the second bypass pipe 323, and the second bypass pipe 323 is equipped with a fourth shut-off valve.

[0086] The anaerobic reactor (IC) 22 is also equipped with a first return pipe 221 at the outlet end, which is connected to the inlet end of the hydrolysis acidification tank 21. Through the first return pipe 221, part of the wastewater treated by the anaerobic reactor (IC) 22 is returned to the hydrolysis acidification tank 21 for secondary hydrolysis acidification treatment to improve the degree of hydrolysis acidification treatment.

[0087] The outlet end of the secondary sedimentation tank 32 is also equipped with a second return pipe 321, which is connected to the inlet end of the aerobic treatment tank 31. Through the second return pipe 321, part of the sewage treated by the secondary sedimentation tank 32 is returned to the aerobic treatment tank 31 for secondary aerobic treatment to improve the degree of aerobic treatment.

[0088] The operating principle of the normal operating mode of the system described in Example 1 is as follows:

[0089] Wastewater from tobacco sheet production (containing COD 3000-3500 mg / L, total nitrogen 60-80 mg / L, pH...) (6-7, ammonia nitrogen 20-40 mg / L) After preliminary filtration by the screen at the top of the collection tank 11, the wastewater enters the collection tank 11 and then enters the rotary drum filter 12 through the pipeline. After being filtered again by the rotary drum filter 12, it enters the primary sedimentation tank 13. Utilizing the principle of gravity sedimentation, settleable and floating matter in the wastewater is flocculated into larger particles, which are then precipitated to the bottom of the tank for preliminary sedimentation. Then, the wastewater enters the equalization tank 14 through the pipeline to regulate the flow rate and water quality. It then enters the hydrolysis acidification tank 21 through the first effluent pipe. Enzymes released by hydrolytic bacteria and acid-producing bacteria promote the biocatalytic reaction of large molecules in the water that are difficult to biodegrade, intercepting and gradually converting non-dissolved organic matter in the wastewater into dissolved organic matter. Finally, the wastewater enters the anaerobic reactor (IC) 22 through the pipeline. Under anaerobic conditions, microorganisms decompose the organic matter through fermentation. The wastewater is broken down into biogas and organic fertilizer, and then enters the aerobic treatment tank 31 through the second effluent pipe. In the aerobic environment, the organic matter is decomposed into inorganic substances such as CO2 and H2O through the aerobic metabolism of microorganisms, releasing energy and emitting oxygen. Then the wastewater enters the secondary sedimentation tank 32 to achieve sludge-water separation, and then enters the primary reaction tank 41 through pipeline. By adding flocculants, pH adjusters and other chemical agents, the wastewater is treated by biochemical methods to remove TN, TP and other substances. Then the wastewater enters the tertiary sedimentation tank 42 through pipeline, where small particles suspended in the water are removed by gravity sedimentation. The wastewater then enters the secondary reaction tank 43 through pipeline for further desalination, hardness reduction, removal of toxic substances and pathogens, and finally enters the quaternary sedimentation tank 44. Based on the tertiary sedimentation tank 42, the wastewater after the secondary reaction tank 43 further settles suspended particles and further removes organic load in the water.

[0090] During this process, the sediment in the primary sedimentation tank 13, secondary sedimentation tank 32, tertiary sedimentation tank 42, and quaternary sedimentation tank 44 enters the sludge thickening tank 51 through the sludge discharge pipe for preliminary thickening, and then enters the sludge balancing tank 52 through the pipeline for balancing and buffering. Finally, the treated sludge is transported off-site.

[0091] The fourth sedimentation tank 44 is equipped with an outlet, and the treated wastewater is discharged in compliance with standards through the outlet pipe. The total effluent indicators are COD < 150 mg / L, total nitrogen < 50 mg / L, pH 6-9, and ammonia nitrogen < 25 mg / L.

[0092] Example 2

[0093] Example 2 provides a method for suppressing the rise of total nitrogen in an aerobic tank of tobacco flake wastewater using the system described in Example 1, specifically including the following steps:

[0094] 1) Shutdown and Micro-aeration Period: After the system stops, the aerobic treatment tank 31 enters the shutdown and micro-aeration period. During this period, a certain amount of carbon source (starch / sugar / tobacco plant extract) and nutrients (N / P fertilizer) are added to the aerobic treatment tank 31 every day. Specifically, during the shutdown and micro-aeration period, 100kg of sugar, 10kg of monoammonium phosphate, and 100L of tobacco plant extract (COD of about 500,000 mg / L) are added to the aerobic treatment tank 31 every day as carbon source (mainly carbon-containing compounds, providing the carbon skeleton of cells for microbial growth and providing the energy required for cell life activities) and other nutrients.

[0095] Meanwhile, intermittent or micro-aeration technology is adopted, with 1 hour of aeration per day (i.e., 1 hour of aeration every 24 hours, with an aeration volume of 10-15 m³ / h). 3 Intermittent aeration ( / h) maintains dissolved oxygen at 0.1-0.6 mg / L, keeping the aerobic treatment tank 31 in a micro-anaerobic state. That is, keeping the aerobic activated sludge (aerobic activated sludge is a flocculent substance formed by the interaction of various microorganisms and organic and inorganic solids in wastewater under aerobic conditions; this flocculent mainly has a core of bacterial flocs formed by bacteria that can play a flocculation role, and various microorganisms such as molds, actinomycetes, yeasts, algae, protozoa and some micro metazoans grow on its surface) in a "semi-dormant" state;

[0096] 2) Activation period: Two days before normal operation, the aerobic treatment tank 31 is continuously aerated to activate the activated sludge for one day. Specifically, by adjusting the frequency of the blower 311, the blower 311 is used to blow air into the aerobic treatment tank 31 through the air inlet pipe, so that the dissolved oxygen in the aerobic treatment tank 31 is controlled at 1-3 mg / L. The color of the sludge in the aerobic treatment tank 31 gradually changes from black to light gray and then to yellowish brown, thus realizing the "activation" of the activated sludge in the aerobic treatment tank 31.

[0097] 3) Consolidation Period: "Consolidation" as used in this application refers to the process where wastewater in the collection tank 11 sequentially passes through the rotary drum filter 12 and the primary sedimentation tank 13 before entering the equalization tank 14. At this time, the first shut-off valve 141 on the first outlet pipe is closed, and the third shut-off valve 143 on the first bypass pipe 142 is opened. The outlet of the equalization tank 14 is connected to the inlet of the aerobic treatment tank 31 through the first bypass pipe 142, forming a "bypass" pipeline that bypasses the anaerobic reactor (IC) 22. This allows wastewater from the equalization tank 14 to be directly introduced into the aerobic treatment tank 31, with a COD of 1500-2000 mg / L and a bypass flow rate of 60 m³. 3 / h;

[0098] Then, the wastewater, containing a mixture of mud and water, overflows from the aerobic treatment tank 31 into the secondary sedimentation tank 32. At this time, the fourth shut-off valve on the second bypass pipe 323 is opened, and the supernatant in the secondary sedimentation tank 32 overflows into the collection tank 11 through the second bypass pipe 323. Simultaneously, some aged sludge is discharged from the bottom of the secondary sedimentation tank 32, with a sludge discharge volume of 2m³. 3 / h (partial aerobic activated sludge discharge from the system to facilitate the growth of new aerobic activated sludge and reduce sludge age), is the "recirculation" process of the system.

[0099] During the circulation consolidation period, the aerobic treatment tank 31 is continuously aerated. By adjusting the frequency of the blower 311, oxygen is introduced into the aerobic treatment tank 31 through the air inlet pipe, keeping the dissolved oxygen in the aerobic treatment tank 31 at 1-3 mg / L. The circulation period is generally 1-2 days. During this period, nutrients (N / P fertilizer), carbon sources (sugar, starch) are added, and sludge is discharged from the secondary sedimentation tank 32 to bring the activated sludge in the aerobic treatment tank 31 into a "normal stable state".

[0100] 4) Normal operation period: After the circulation consolidation period is completed, close the third shut-off valve 143 on the first bypass pipe 142, open the first shut-off valve 141 on the first outlet pipe, and open the second shut-off valve 322 on the third outlet pipe to enter the normal operation period; during the normal operation period, a certain amount of carbon source (starch / sugar / tobacco plant extract) and nutrients (N / P fertilizer) are added to the aerobic treatment tank 31 every day.

[0101] The normal operating mode is:

[0102] Wastewater from tobacco sheet production (containing COD 3000-3500 mg / L, total nitrogen 60-80 mg / L, pH...) (6-7, ammonia nitrogen 20-40 mg / L) After preliminary filtration by the screen at the top of the collection tank 11, the wastewater enters the collection tank 11 and then enters the rotary drum filter 12 through the pipeline. After being filtered again by the rotary drum filter 12, it enters the primary sedimentation tank 13. Utilizing the principle of gravity sedimentation, settleable and floating matter in the wastewater is flocculated into larger particles, which are then precipitated to the bottom of the tank for preliminary sedimentation. Then, the wastewater enters the equalization tank 14 through the pipeline to regulate the flow rate and water quality. It then enters the hydrolysis acidification tank 21 through the first effluent pipe. Enzymes released by hydrolytic bacteria and acid-producing bacteria promote the biocatalytic reaction of large molecules in the water that are difficult to biodegrade, intercepting and gradually converting non-dissolved organic matter in the wastewater into dissolved organic matter. Finally, the wastewater enters the anaerobic reactor (IC) 22 through the pipeline. Under anaerobic conditions, microorganisms decompose the organic matter through fermentation. The wastewater is broken down into biogas and organic fertilizer, and then enters the aerobic treatment tank 31 through the second effluent pipe. In the aerobic environment, the organic matter is decomposed into inorganic substances such as CO2 and H2O through the aerobic metabolism of microorganisms, releasing energy and emitting oxygen. Then the wastewater enters the secondary sedimentation tank 32 to achieve sludge-water separation, and then enters the primary reaction tank 41 through pipeline. By adding flocculants, pH adjusters and other chemical agents, the wastewater is treated by biochemical methods to remove TN, TP and other substances. Then the wastewater enters the tertiary sedimentation tank 42 through pipeline, where small particles suspended in the water are removed by gravity sedimentation. The wastewater then enters the secondary reaction tank 43 through pipeline for further desalination, hardness reduction, removal of toxic substances and pathogens, and finally enters the quaternary sedimentation tank 44. Based on the tertiary sedimentation tank 42, the wastewater after the secondary reaction tank 43 further settles suspended particles and further removes organic load in the water.

[0103] During this period, the sediment in the primary sedimentation tank 13, secondary sedimentation tank 32, tertiary sedimentation tank 42 and quaternary sedimentation tank 44 enters the sludge thickening tank 51 through the sludge discharge pipe for preliminary thickening, and then enters the sludge balancing tank 52 through the pipeline for balancing and buffering. Finally, the treated sludge is transported off-site.

[0104] The fourth sedimentation tank 44 is equipped with an outlet, and the treated wastewater is discharged in compliance with standards through the outlet pipe. The total effluent indicators are COD < 150 mg / L, total nitrogen < 50 mg / L, pH 6-9, and ammonia nitrogen < 25 mg / L.

[0105] Subsequently, by cyclically running steps 1), 2), 3), and 4), the rise of total nitrogen in the aerobic treatment tank 31 can be suppressed.

[0106] The system and method described in this invention suppress the rise of total nitrogen in the aerobic tank by sequentially performing an operation mode of "shutdown micro-aeration period - smoldering aeration activation period - circulation consolidation period - normal operation period", thereby extending the service life of the system.

[0107] After the implementation of this invention, compared with commonly used technical means, it avoids the input of a large amount of carbon source and reduces aeration energy consumption; the activated sludge in the aerobic treatment tank successively goes through the "semi-dormant state", "activated state" and "normal stable state", avoiding problems such as aerobic sludge aging and sludge deflocculation, and seamlessly connects to normal operation, suppressing the problem of total nitrogen rise during the shutdown and restart of the tobacco sheet wastewater aerobic treatment tank.

[0108] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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. They should not be construed as limiting the specific protection scope of this invention.

[0109] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0110] Finally, it should be noted that the above are merely preferred embodiments and application principles of the present invention. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include many other effective embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for suppressing the increase in total nitrogen during the restart of an aerobic tank for tobacco flake wastewater, characterized in that, This is achieved by a system that suppresses the rise in total nitrogen during the restart of the aerobic tank for tobacco sheet wastewater. The system includes a pretreatment unit, an anaerobic treatment unit, an aerobic treatment unit, an advanced treatment unit, and a sludge treatment unit. The system suppresses the rise in total nitrogen in the aerobic treatment unit by performing maintenance during shutdown phases. The pretreatment mechanism includes a water collection tank, a rotary drum filter, a primary sedimentation tank, and an equalization tank, which are connected in sequence through a liquid phase flow pipeline. The anaerobic treatment unit includes a hydrolysis acidification tank and an anaerobic reactor that are connected in sequence through a liquid phase flow pipeline. The wastewater discharge end of the equalization tank is connected to the inlet end of the hydrolysis acidification tank through the first outlet pipe; The aerobic treatment mechanism includes an aerobic treatment tank and a secondary sedimentation tank that are connected in sequence through a liquid phase flow pipeline. The wastewater discharge end of the anaerobic reactor is connected to the inlet end of the aerobic treatment tank through a second effluent pipe. The advanced treatment mechanism includes a primary reaction tank, a tertiary sedimentation tank, a secondary reaction tank, and a quaternary sedimentation tank, which are connected in sequence through liquid phase flow pipelines. The wastewater discharge end of the secondary sedimentation tank is connected to the inlet end of the primary reaction tank through a third outlet pipe. The sludge treatment facility includes a sludge thickening tank and a sludge balancing tank connected in sequence by pipelines. The first outlet pipe is equipped with a first shut-off valve; the third outlet pipe is equipped with a second shut-off valve; The outlet of the equalization tank is also connected to the inlet of the aerobic treatment tank through a first bypass pipe; a third shut-off valve is provided on the first bypass pipe. The outlet of the secondary sedimentation tank is connected to the collection tank through a second bypass pipe; a fourth shut-off valve is installed on the second bypass pipe. The method includes the following steps: 1) Shutdown and micro-aeration period: After the system stops, the aerobic treatment tank enters the shutdown and micro-aeration period. During this period, a certain amount of carbon source and nutrients are added to the aerobic treatment tank every day. At the same time, intermittent or micro-aeration process is used to intermittently aerate the aerobic treatment tank, so that the aerobic treatment tank is in a micro-anaerobic state and the aerobic activated sludge is in a "semi-dormant" state. 2) Activation period: The aerobic treatment tank adopts continuous aeration and the activated sludge in the aerobic treatment tank is activated by 1-2 days of continuous aeration. 3) Consolidation period: The sewage in the collection tank passes through the rotary drum filter and the primary sedimentation tank in sequence and enters the equalization tank. At this time, the first shut-off valve on the first outlet pipe is closed and the third shut-off valve on the first bypass pipe is opened. The outlet of the equalization tank is connected to the inlet of the aerobic treatment tank through the first bypass pipe, forming a "beyond" pipeline that does not pass through the anaerobic reactor, and the sewage in the equalization tank is directly introduced into the aerobic treatment tank. Then, the sewage containing the mud-water mixture in the aerobic treatment tank overflows into the secondary sedimentation tank. At this time, the fourth shut-off valve on the second bypass pipe is opened, and the supernatant in the secondary sedimentation tank flows into the collection tank through the second bypass pipe in an overflow manner, which is the "circulation" process. 4) Normal operation period: After the circulation consolidation period is completed, close the third shut-off valve on the first bypass pipe, open the first shut-off valve on the first outlet pipe, open the second shut-off valve on the third outlet pipe, and enter the normal operation period. Subsequently, by repeating steps 1), 2), 3), and 4), the rise in total nitrogen in the aerobic treatment tank can be suppressed.

2. The method according to claim 1, characterized in that, The aerobic treatment tank is connected to an air inlet pipe, and a blower is installed on the air inlet pipe.

3. The method according to claim 1, characterized in that, The anaerobic reactor is also equipped with a first reflux pipe at the outlet end, which is connected to the inlet end of the hydrolysis acidification tank.

4. The method according to claim 1, characterized in that, The outlet of the secondary sedimentation tank is also equipped with a second return pipe, which is connected to the inlet of the aerobic treatment tank.

5. The method according to claim 1, characterized in that, In step 2), the activated sludge in the aerobic treatment tank is aerated by adjusting the blower frequency and using the blower to blow air into the aerobic treatment tank through the air inlet pipe, so that the dissolved oxygen in the aerobic treatment tank is controlled at 1-3 mg / L. The color of the sludge in the aerobic treatment tank gradually changes from black to light gray and then to yellowish brown, thus realizing the "activation" of the activated sludge in the aerobic treatment tank.

6. The method according to claim 1, characterized in that, In step 3), while the supernatant in the secondary sedimentation tank overflows into the collection tank through the second bypass pipe, a portion of aged sludge is discharged from the bottom of the secondary sedimentation tank, with a sludge discharge volume of 1-5 m³. 3 / h.

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