An energy-saving biofilter system and design method for odor treatment in food waste plants

Abstract

The present invention proposes an energy-saving biological filter system and design method for odor treatment in a food waste plant, which solves the problems of low optimization degree and easy waste of resources in conventional odor treatment equipment. Its main technical solution includes that the water in the biological washing section corresponding to high and low concentration odor is self-circulated through a circulation mechanism, the circulation mechanism includes a high-concentration buffer water tank for nitrification reaction and a low-concentration buffer water tank for denitrification reaction, the high-concentration biological washing section is connected to the high-concentration buffer water tank, one end of the high-concentration buffer water tank is connected to the high-concentration biological washing section through a first circulation water pump to achieve internal circulation, and the other end is connected to the low-concentration buffer water tank, the low-concentration buffer water tank is connected to the high-concentration buffer water tank through a second circulation water pump to achieve internal circulation, the low-concentration biological washing section is connected to the denitrification reaction section through the second circulation water pump, the second circulation water pump is also connected to the external sedimentation tank and the supernatant temporary storage tank in sequence, and the supernatant part in the supernatant temporary storage tank is connected to the high-concentration buffer water tank.

Description

Technical Field

[0001] The present invention relates to the technical field of kitchen waste odor treatment, and in particular to an energy-saving biofilter system for treating odor in a restaurant kitchen waste plant. Background Art

[0002] With the rapid promotion of garbage classification in various cities in my country, the construction of food waste treatment plants has been steadily implemented in various places. At the same time, odor treatment facilities need to be built simultaneously during the operation of food waste treatment plants. Since the odors generated during the operation of food waste treatment plants are mainly odors produced by microbial metabolism such as ammonia, VOC, hydrogen sulfide, and methyl mercaptan, the current treatment of this type of odor mostly adopts the biological filter process, or a combination process with the biological filter process as the core.

[0003] 1. The odor treatment capacity of food waste treatment plants is designed according to the technical requirements of the "Technical Specification for Food Waste Treatment" (CJJ 184-2012). The overall air exchange rate for each pollutant (odor)-producing structure is no less than 3 times / hour. Therefore, the terminal treatment system of food waste treatment plants is relatively large, and most use two or more sets of treatment equipment in parallel. At the same time, high-concentration terminal treatment equipment and low-concentration terminal treatment equipment are installed according to odor concentration. Due to the differences in odor concentration and operating mode among the various structures within the plant, the circulating water quality and microbial growth conditions in the biofilter beds in each terminal treatment system vary. Currently, the biological washing section does not circulate or discharges the wastewater at regular intervals after circulation. The high-concentration wastewater produces higher pollutant concentrations, while the low-concentration equipment produces relatively lower pollutant concentrations. The discharge of low-concentration wastewater not only wastes water resources but also causes an imbalance in the carbon dioxide (C / N) ratio in subsequent sewage treatment plants.

[0004] 2. The odor generated during the operation of pretreatment facilities at domestic food waste plants is primarily ammonia and methyl mercaptan, and is present in high concentrations. To reduce the load on the biological deodorization filter, the current mainstream process adds a chemical scrubbing process to the front end of the biological filter, using acid-base neutralization to remove alkaline gases such as ammonia from the odor. The addition of chemical agents such as sulfuric acid can improve the ammonia removal rate in the system. However, sulfuric acid is currently a controlled chemical, and its storage and use are relatively strict, increasing the difficulty of subsequent operation and management.

[0005] 3. Ammonia is a gas that is highly soluble in water. It can be removed by water washing without adding chemical agents. However, since ammonia water can easily volatilize ammonia, the circulating liquid needs to be discharged in time after adsorbing ammonia, which results in a large amount of wastewater discharged. Moreover, this part of wastewater has a high ammonia nitrogen content and a low COD concentration. It is a low-concentration wastewater with a low C / N ratio. After a large amount of discharge, the C / N ratio of the factory sewage system will be further unbalanced, which will increase the difficulty of subsequent treatment and cause waste of water resources.

[0006] 4. Due to a lack of effective disturbance in the water reservoir at the bottom of the biofilter, biofilm detached from the existing filter bed and dust trapped in the washing section will settle at the bottom. Over time, these substances, due to long-term lack of oxygen, will cause anaerobic digestion of organic matter in the sediment, releasing hydrogen sulfide and ammonia, resulting in excessive exhaust emissions. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes an energy-saving biological filter system for odor treatment in food waste plants, which can reasonably utilize the time difference of the deodorization system operation, effectively regenerate the circulating liquid, and reduce the amount of sewage discharged by the system.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is: an energy-saving biological filter system for odor treatment in a food waste plant, comprising biological treatment equipment corresponding to high and low concentration odors respectively, the biological treatment equipment comprising a biological washing section, the water in the biological washing sections corresponding to high and low concentration odors is self-circulated through a circulation mechanism, the circulation mechanism comprising a high-concentration buffer water tank for nitrification reaction and a low-concentration buffer water tank for denitrification reaction, the high-concentration biological washing section is connected to the high-concentration buffer water tank, one end of the high-concentration buffer water tank is connected to the high-concentration biological washing section through a first circulating water pump to achieve internal circulation, and the other end is connected to the low-concentration buffer water tank, the low-concentration buffer water tank is connected to the high-concentration buffer water tank through a second circulating water pump to achieve internal circulation, the low-concentration biological washing section is connected to the denitrification reaction section through the second circulating water pump to achieve internal circulation, the second circulating water pump is also connected to an external sedimentation tank and a supernatant storage tank in sequence, and the supernatant portion in the supernatant storage tank is connected to the high-concentration buffer water tank.

[0009] Furthermore, the high-concentration biological treatment equipment includes an acidic washing section, a high-concentration biological washing section and a high-concentration biological filtration section in sequence, the acidic washing section is sodium bisulfate washing, and the low-concentration biological treatment equipment includes a low-concentration biological washing section and a low-concentration biological filtration section in sequence, and the odor in the high-concentration biological filtration section and the low-concentration biological filtration section are respectively discharged to the exhaust gas emission tower through negative pressure fans.

[0010] Furthermore, the high-concentration buffer water tank and the low-concentration buffer water tank are built into the biological treatment equipment and are respectively connected to a blower.

[0011] Furthermore, the bottom of the high-concentration buffer water tank is microporous aeration, and the bottom of the low-concentration buffer water tank is perforated aeration.

[0012] Furthermore, a carbon source adding device is provided between the nitrification reaction section and the denitrification reaction section.

[0013] Furthermore, the sodium bisulfate liquid is added to the acid washing section through a dosing device, and the acid washing section is self-circulated through a third circulation pump.

[0014] A design method for an energy-saving biofilter system for treating odor in a food waste plant, wherein the design method for the denitrification reaction section and the nitrification section comprises the following steps:

[0015] S1. First, measure the ammonia concentration and organic matter concentration in high and low concentration odors, calculate the conversion rate of pollutants from the air to water at 60-70%, and estimate the total amount of pollutants transferred to the water each day. Ammonia nitrogen and COD pollutant indicators are introduced, and then the pollutant concentration in the buffer water tank is calculated as the raw water indicator;

[0016] S2. After treatment by the system, the circulating water is assumed to meet the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" GB 18918-2002, Level B standard;

[0017] S3. Based on the national standards HJ 578-2010, Technical Specifications for Sewage Treatment Engineering Using Oxidation Ditch Activated Sludge Method, and HJ 2009-2011, the following data were calculated through carbon removal and nitrogen removal:

[0018] The amount of oxygen required for nitrification and carbon removal in the nitrification section guides the selection of high-concentration blowers.

[0019] The volume of the nitrification reaction section and the denitrification reaction section guides the amount of biological filler to be filled;

[0020] In S4, denitrification section, in order to ensure dissolved oxygen ≤ 0.5 mg / L, perforated pipe stirring method is adopted, and the stirring air volume is 3m 3 / m 2 Calculation to guide the selection of low-concentration blowers.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Taking full advantage of the different operating times and pollutant release concentrations of each treatment unit in a food waste plant, the system uses a negative pressure fan to introduce workshop odor into the deodorization system for treatment during daytime operation. After the pollutants pass through the biological washing section, most of the water-soluble pollutants are dissolved in the water. At night, when the system is stopped, the circulating water is regenerated. The present invention adds a nitrification / denitrification section to the buffer water tank to remove water-soluble pollutants such as ammonia nitrogen and organic matter. Solid suspended matter in the circulating water is then removed through mud and water separation. Part of the supernatant is discharged, and most of it is returned to the high-concentration buffer water tank for reuse, saving water and reducing filter clogging.

[0023] 2. Reasonably utilize the time difference of the deodorization system operation to effectively regenerate the circulating fluid and reduce the amount of wastewater discharged from the system;

[0024] 3. Use solid acid sodium sulfate instead of sulfuric acid as ammonia adsorbent to solve the problem of sulfuric acid use in the later stage;

[0025] 4. The high and low concentration buffer water tanks are connected by pipes to effectively form a loop to avoid water flow interruption. At the same time, aeration facilities are installed at the bottom of the water tank. Microporous aerators are used in the nitrification section, and perforated aeration is used in the denitrification section to effectively prevent the precipitation of suspended matter and eliminate anaerobic digestion of organic matter.

[0026] 5. Effectively denitrify sewage and reduce the denitrification load of subsequent sewage treatment plants;

[0027] 6. The nitrification and denitrification sections of the system utilize the built-in buffer water tanks of the biological treatment equipment, and no additional equipment is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them:

[0029] Figure 1 The overall framework diagram proposed according to one embodiment of the present invention is schematically shown.

[0030] Numbers in the figure: 01, acid washing section; 02, high-concentration biological washing section; 03, high-concentration biological filtration section; 04, high-concentration negative pressure fan; 05, third circulating water pump; 06, first circulating water pump; 07, dosing device; 08, high-concentration buffer water tank; 09, nitrification reaction section; 10, high-concentration blower; 11, low-concentration buffer water tank; 12, denitrification reaction section; 13, low-concentration blower; 14, carbon source dosing device; 15, low-concentration biological washing section; 16, low-concentration biological filtration section; 17, low-concentration negative pressure fan; 18, exhaust gas emission tower; 19, sedimentation tank; 20, supernatant storage tank; 21, second circulating water pump. DETAILED DESCRIPTION

[0031] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0032] According to one embodiment of the present invention, Figure 1The odor must be effectively treated during the food waste treatment process. Gas collected within the station is divided into high-concentration and low-concentration odors. High-concentration odors are primarily emitted by various equipment (such as heating pulping, discharge chutes, and sorting devices), while low-concentration odors are primarily emitted by the overall ventilation of each treatment workshop. Typically, the food waste pretreatment workshop operates from 6:00 AM to 6:00 PM daily, with operations suspended at night.

[0033] When the system is running during the day, high-concentration odor enters the high-concentration biological treatment equipment for treatment, and low-concentration odor enters the low-concentration biological treatment equipment for treatment. After treatment, the gas meets the emission standards:

[0034] For high-concentration odor, the corresponding high-concentration biological treatment equipment is a strong deammonification device. First, the high-concentration odor is pre-treated through the acid washing section 01. During washing, acidic liquid is added through the external automatic dosing device 07. The treatment process is also circulated multiple times through the third circulation pump to ensure sufficient acid-base reaction. The acidic liquid uses solid acid sodium sulfate instead of sulfuric acid as an ammonia adsorbent to remove most of the alkaline gas in the high-concentration odor and generate substances such as ammonium bisulfate. At the same time, it also avoids the storage and control problems brought about by the conventional use of sulfuric acid. The high-concentration odor is then treated by the high-concentration biological washing section 02 to transfer most of the gaseous ammonia and organic pollutants into the water. At the same time, the first circulating pump circulates and sprays, reducing the subsequent biological filter equipment processing load. However, at the same time, the ammonia nitrogen transferred to the water is only a process of transferring the pollution source. As the number of cycles increases, the ammonia nitrogen in the circulating liquid is precipitated again as ammonia gas through the stripping effect. Therefore, the circulating liquid needs to be discharged in time. In order to achieve the purpose of water saving, this solution adopts the principle of enhanced deammonification for regeneration. This part of the water needs to enter the high-concentration buffer water tank 08 and the low-concentration buffer water tank 11 in turn for nitrification and denitrification treatment. The high-concentration buffer water tank 08 converts the ammonia nitrogen in the water into nitrate nitrogen, which is returned to the low-concentration buffer water tank 11 through the second cycle to denitrify the nitrate nitrogen and finally precipitate as nitrogen gas. Through the second cycle, the system makes the high-concentration buffer water tank 08 and the low-concentration buffer water tank 11 form an operation mode similar to the oxidation ditch (circulating water passes through the nitrification section / denitrification section / nitrification section in turn). After the reaction is completed, the liquid is discharged to the sedimentation tank 19 for precipitation, removing suspended matter in the liquid and effectively reducing nozzle clogging.

[0035] For low-concentration odor, due to its low COD and low ammonia nitrogen, it belongs to low-concentration wastewater with low pollutant concentration. After a large amount of discharge, it is easy to cause an imbalance in the C / N ratio of the factory sewage system. The low-concentration buffer water tank 11 is returned to the high-concentration buffer water tank 08 through the second circulating water pump 21, which can effectively dilute the circulating water of the high-concentration buffer water tank 08, and then the first circulating water pump 06 is used to absorb pollutants such as ammonia in the high-concentration biological washing section 02.

[0036] Finally, the high-concentration odor and low-concentration odor are treated with recycled wastewater after sufficient reaction in the sedimentation tank 19. After sedimentation, the solid residue at the bottom is transported to the outside for treatment. The separated supernatant flows into the supernatant temporary storage tank. At the same time, the supernatant temporary storage tank is connected to the high-concentration buffer water tank 08 to continue to be used for subsequent high-concentration odor reaction treatment. The residence time of the nitrification reaction is calculated according to the following method:

[0037] Ammonia nitrogen concentration of circulating water after treatment: C N-N出 , 5mg / L (refer to GB18918-2002 "Pollutant Discharge Standard for Urban Wastewater Treatment Plants"), COD concentration of circulating water after treatment: C cod出 , 40mg / L (refer to GB18918-2002 "Pollutant Discharge Standard for Urban Wastewater Treatment Plants"),

[0038] Ammonia nitrogen concentration transferred to circulating water:

[0039]

[0040] COD concentration transferred to circulating water:

[0041]

[0042] Among them, Q1 is the high concentration processing air volume, Q2 is the low concentration processing air volume, C N1 is the ammonia concentration in high concentration odor, C N2 is the ammonia concentration in low concentration odor, C c1 is the concentration of organic matter in high concentration odor, C c2 is the concentration of organic matter in low-concentration odor, t is the system operation time, V d1 is the volume of high concentration buffer water tank, V d2 is the volume of the low concentration buffer water tank.

[0043] For the nitrification reaction section volume V n1 and the volume of the denitrification reaction section V n2 , calculated according to the Technical Specifications for Oxidation Ditch Activated Sludge Wastewater Treatment Engineering (HJ 578-2010),

[0044] 1. Volume of nitration reaction section: V n1 , calculation method:

[0045] (1) Calculation of chemical demand volume load V n1

[0046]

[0047] Note: M c --Volume load of chemical oxygen demand for organic matter removed in nitrification reaction section, kgCOD / (m3 Filler.d)

[0048] (2) Calculation of denitrification reaction V n1

[0049]

[0050] Note: M N - Nitrification reaction section nitrification volume load, kgTKN / (m 3 Filler.d)

[0051] (3) The larger volume of the two is taken as the volume of the nitration reaction section: V n1

[0052] 2. Denitrification reaction section volume: V n2 calculate

[0053]

[0054] Note: M DNL – Denitrification volumetric load, kgNO X -N / (m 3 Filler.d)

[0055] For low concentration negative pressure fan aeration volume, the aeration intensity is 3m 3 / m 2 h. Model selection: The aeration capacity of high-concentration blowers shall be calculated and selected according to the Technical Specifications for Oxidation Ditch Activated Sludge Process Wastewater Treatment Engineering (HJ 578-2010).

[0056] 1. Selection of aeration volume for high concentration blower:

[0057] Nitrification reaction section gas-water ratio: N:1, then the air volume (m 3 / d):(N:1)×(V d1 +V d2 )

[0058] 2. Selection of low concentration blower aeration volume:

[0059] The aeration intensity of the denitrification section is 3m 3 / m 2 h, then the air volume (m 3 / h): 3m 3 / m 2 h×V d2 ÷H

[0060] Note: H is the water storage height of the low concentration buffer water tank

[0061] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. An energy-saving biofilter system for treating odor in food waste plants, comprising biological treatment equipment corresponding to high and low concentration odors, each of which includes a high-concentration biological washing section and a low-concentration biological washing section, characterized by: The water in the biological washing section corresponding to high and low concentration odors is self-circulated through a circulation mechanism, which includes a high concentration buffer water tank for nitrification reaction and a low concentration buffer water tank for denitrification reaction. The high-concentration biological washing section is connected to the high-concentration buffer water tank. One end of the high-concentration buffer water tank is connected to the high-concentration biological washing section through a first circulating water pump to realize internal circulation, and the other end is connected to the low-concentration buffer water tank. The low-concentration buffer water tank realizes internal circulation through the second circulating water pump and the high-concentration buffer water tank, and the low-concentration biological washing section realizes internal circulation through the second circulating water pump and the denitrification reaction section. The second circulating water pump is also connected to the external sedimentation tank and the supernatant temporary storage tank in sequence, and the supernatant in the supernatant temporary storage tank is connected to the high-concentration buffer water tank. The high-concentration biological treatment equipment includes an acidic washing section, a high-concentration biological washing section and a high-concentration biological filtration section in sequence. The acidic washing section is sodium bisulfate washing. The low-concentration biological treatment equipment includes a low-concentration biological washing section and a low-concentration biological filtration section in sequence. The odor in the high-concentration biological filtration section and the low-concentration biological filtration section is discharged to the tail gas emission tower through a negative pressure fan. A carbon source adding device is also provided between the nitrification reaction section and the denitrification reaction section.

2. The energy-saving biofilter system for treating odor in a food waste plant according to claim 1, characterized in that: The high-concentration buffer water tank and the low-concentration buffer water tank are built into the biological treatment equipment and are respectively connected to a blower.

3. The energy-saving biofilter system for treating odor in a food waste plant according to claim 1 is characterized in that: The bottom of the high-concentration buffer water tank is microporous aeration, and the bottom of the low-concentration buffer water tank is perforated aeration.

4. The energy-saving biofilter system for treating odor in a food waste plant according to claim 1, characterized in that: The sodium bisulfate liquid is added to the acid washing section through a dosing device, and the acid washing section is self-circulated through a third circulation pump.

5. The design method of an energy-saving biofilter system for treating odor in a food waste plant according to any one of claims 1 to 4, characterized in that The denitrification reaction section and nitrification section design method comprises the following steps: S1. First, measure the ammonia concentration and organic matter concentration in high and low concentration odors, calculate the conversion rate of pollutants from the air to water at 60-70%, and estimate the total amount of pollutants transferred to the water each day. Ammonia nitrogen and COD pollutant indicators are introduced, and then the pollutant concentration in the buffer water tank is calculated as the raw water indicator; S2. After treatment by the system, the circulating water is assumed to meet the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" GB 18918-2002, Level B standard; S3. Based on the national standards HJ 578-2010, Technical Specifications for Sewage Treatment Engineering Using Oxidation Ditch Activated Sludge Method, and HJ 2009-2011, the following data were calculated through carbon removal and nitrogen removal: The amount of oxygen required for nitrification and carbon removal in the nitrification section guides the selection of high-concentration blowers. The volume of the nitrification reaction section and the denitrification reaction section guides the amount of biological filler to be filled; In S4, denitrification section, in order to ensure dissolved oxygen ≤ 0.5 mg / L, perforated pipe stirring method is adopted, and the stirring air volume is 3m 3 / m 2 Calculation to guide the selection of low-concentration blowers.

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