Equipment and method for preparing carbon source and efficiently and synergistically removing ammonia nitrogen for kitchen

Abstract

The invention provides equipment and a method for preparing a carbon source and efficiently and synergistically removing ammonia nitrogen for a kitchen, and belongs to the technical field of kitchen waste treatment. The equipment comprises an acid production system and an electro-catalysis system, one end of the acid production system is connected with a raw material tank, one end of the electro-catalysis system is connected with a finished product tank, and the acid production system and the electro-catalysis system are connected through a circulating system. The method comprises the following specific steps of: pumping crushed and homogenized kitchen slurry into an anaerobic fermentation acid production tank by a screw pump through a feed port to realize a kitchen acid production process; the anaerobic fermentation acid production tank and the electro-catalysis reaction tank form a closed cycle, so that a fermentation mixed solution circularly flows; the electro-catalysis system is in an up-flow type, and after solid and liquid are separated through the upper inclined plate separator, materials are discharged through a discharging groove. According to the invention, acid production and electro-catalysis systems are coupled, and the obtained product can provide an effective carbon source for deep denitrification of wastewater with a low carbon-nitrogen ratio.

Description

Background Art

[0002] Food waste has the characteristics of high organic matter content and high water content. The main treatment technologies currently include composting, landfill, incineration, anaerobic acid production and biogas. Among them, anaerobic fermentation acid production technology has attracted much attention due to its resource recovery and environmentally friendly characteristics. This technology can not only promote the reduction of food waste but also realize resource utilization. During the anaerobic fermentation process of food waste, macromolecular organic matter such as polysaccharides and proteins are hydrolyzed and converted into small molecular organic acids with high added value. At the same time, the problem of low C / N ratio (carbon-nitrogen ratio) of municipal sewage and industrial park wastewater is becoming increasingly prominent, which requires the addition of a large amount of commercial carbon source in the denitrification stage, thereby increasing the operating cost of sewage treatment plants. In view of this, converting food waste into acid-producing fermentation liquid through anaerobic fermentation and using it as a carbon source supply in the denitrification stage is a hot topic in current research. This measure can not only realize the resource utilization of food waste, but also effectively reduce the operating cost of sewage treatment plants. However, during the anaerobic fermentation of food waste, while protein is degraded into small molecular acids, ammonia nitrogen will be produced. If the fermentation liquid is directly added to the denitrification stage, it will undoubtedly increase the nitrogen load of the system and affect the treatment effect. Therefore, how to solve the high ammonia nitrogen problem when the fermentation liquid is used as a carbon source for denitrification is of great significance for realizing the resource utilization of food waste.

[0003] There are still many deficiencies in the existing technology, such as: (1) In the process of traditional anaerobic fermentation of food waste to produce acid, the substrate protein will be hydrolyzed and converted into high-concentration ammonia nitrogen, so the fermentation liquid cannot be directly used as a carbon source. (2) The high concentration of ammonia nitrogen contained in the food waste fermentation liquid has high requirements for the impact resistance of the anaerobic fermentation acid production reactor, which may produce negative feedback on the anaerobic fermentation system, resulting in a decrease in the conversion rate of food waste to produce acid. (3) Traditional anaerobic fermentation reactors need to be regularly discharged to remove some aging microorganisms and metabolites to maintain the activity and decomposition efficiency of microorganisms, otherwise it will affect the anaerobic environment in the reactor, resulting in the inhibition of the growth and metabolism of anaerobic microorganisms. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a device and method for preparing a carbon source for kitchen waste and efficiently removing ammonia nitrogen. - ClO produced in the electrocatalytic system - and Cl2 to enhance cell wall disruption, increase acid production and achieve efficient denitrification.

[0005] In order to achieve the purpose of the present invention, the following technical scheme is adopted: A device for preparing carbon sources for kitchen waste and efficiently removing ammonia nitrogen, the device comprising an acid generating system and an electrocatalytic system, one end of the acid generating system is connected to a raw material tank, one end of the electrocatalytic system is connected to a finished product tank, and the acid generating system and the electrocatalytic system are connected via a circulation system; Preferably, the acid production system comprises an anaerobic fermentation acid production tank and a stirrer, wherein the stirring portion of the stirrer extends into the interior of the anaerobic fermentation acid production tank; the electrocatalytic system comprises an electrocatalytic reaction tank, wherein a catalytic electrode plate is provided inside the electrocatalytic reaction tank; Preferably, the circulation system includes a pipeline forming a closed loop between the anaerobic fermentation acid production tank and the electrocatalytic reaction tank, a circulation pump and a circulation port arranged in the anaerobic fermentation acid production tank or the electrocatalytic reaction tank. Specifically, the side wall of the anaerobic fermentation acid production tank is provided with upper and lower circulation ports; in the electrocatalytic reaction tank, two circulation ports are arranged at the bottom and upper side of the electrode plate.

[0006] Further preferably, an inclined plate separator and a discharge port are provided on the upper portion of the catalytic electrode plate, and the electrocatalytic reaction tank is connected to the finished product tank via the discharge port.

[0007] As another technical solution of the present invention: A method for preparing a carbon source for kitchen waste and efficiently removing ammonia nitrogen, the method is implemented using the equipment in the above technical solution, and specifically comprises the following steps: S1. The crushed and homogenized food waste slurry is pumped into the anaerobic fermentation acid production tank through the feed port by a screw pump, and the materials are fully mixed under the action of the agitator to realize the food waste acid production process; S2, the circulation port at the upper end of the side wall of the anaerobic fermentation acid production tank is connected to the circulation port at the bottom of the electrocatalytic reaction tank through a circulation pump, and the circulation port at the upper part of the electrocatalytic reaction tank is connected to the bottom of the anaerobic fermentation acid production tank to form a closed loop, so that the fermentation mixed liquid circulates; S3. The electrocatalytic system is of upflow type. The upper inclined plate separator separates the solid and liquid and then discharges the material through the discharge trough.

[0008] Preferably, the steps are specifically as follows: S1, the food waste slurry stored in the raw material tank enters the anaerobic fermentation acid production tank through a feed pump, is fully mixed with the inoculated sludge in the anaerobic fermentation acid production tank, and is fermented under anaerobic conditions, and the macromolecular organic matter in the food waste slurry is hydrolyzed and converted into small molecular organic acids, CO2, ammonia nitrogen and other substances; S2. During the anaerobic fermentation process, the fermentation mixture circulates between the anaerobic acid production fermentation tank and the electrocatalytic reaction tank, and the Cl in the kitchen slurry is converted into - Conversion to ClO - It reacts with Cl2 and ammonia nitrogen to generate nitrogen gas, and at the same time strengthens the cell wall breaking of kitchen utensils, further promoting their acid production; S3. The electrocatalytic system is an upflow type. The upper inclined plate separator separates the solid and liquid. After the anaerobic fermentation is completed, the fermentation liquid enters the finished product tank through the discharge port for standby use.

[0009] Preferably, in the continuous flow operation mode of the method, the organic load of the kitchen slurry is 10-30 gVS / L, the hydraulic retention time is between 4-12 days; the system temperature is controlled between 25-37°C, and the pH value is not adjusted during operation and is stable between 5.0-6.5; Preferably, Cl in the kitchen slurry - The concentration is not less than 2000 mg / L, Cl - ClO produced in the electrocatalytic system - and Cl2 to strengthen cell wall disruption, increase acid production and achieve efficient nitrogen removal, with a salt content of no less than 6000 mg / L; Preferably, the voltage of the electrocatalytic system is controlled between 5-7 V and the current density is between 40-60 mA / cm 2 ; Preferably, the residence time of the mixed solution in the electrocatalytic system is about 60 min, of which 50% is the electrocatalytic time and 50% is the ClO - and Cl2 buffer decay time.

[0010] Compared with the prior art, the present invention achieves the following technical effects: (1) The electrocatalytic system can utilize Cl in kitchen waste - Conversion to ClO - Cl2 reacts with ammonia nitrogen to generate nitrogen gas which escapes, thereby reducing the ammonia nitrogen concentration in the reactor, optimizing the composition of the fermentation liquid, and saving processes and costs for the subsequent use of the fermentation liquid.

[0011] (2) In the electrocatalytic system, ClO - Not only does Cl2 react with ammonia nitrogen to effectively reduce its concentration, but it also breaks down the cells in kitchen waste, further improving the efficiency of converting substrates into volatile acids.

[0012] (3) In this system, a voltage of 5-7 V will not only break the cell walls of the kitchen kitchen cells, but also break the walls of some aged sludge, causing it to act as a substrate for acid production. This can eliminate the need for sludge discharge and increase the substrate concentration, allowing it to further produce acid.

[0013] (4) Using this method, the volatile acid conversion rate is more than 50%, the carbon source conversion rate is more than 90%, the sludge yield is reduced by about 30%, and the ammonia nitrogen removal rate is more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For ease of explanation, the present invention is described in detail with reference to the following specific embodiments and the accompanying drawings.

[0015] Figure 1 This is a schematic diagram of the device of Example 1 of the present invention. Among them: 1. Raw material tank; 2. Feed pump; 3. Anaerobic fermentation acid production tank; 4. Agitator; 5. Electrocatalytic reaction tank; 6. Electrode plate; 7. Inclined plate separator; 8. Power supply; 9. Discharge port; 10. Circulation pump; 11. Finished product tank.

[0016] Figure 2 This is a graph showing changes in volatile acid concentration in Example 3 of the present invention.

[0017] Figure 3 This is a graph showing changes in ammonia nitrogen concentration in Example 3 of the present invention.

[0018] Figure 4 This is a diagram showing the proportion of volatile acid components in Example 3 of the present invention. DETAILED DESCRIPTION

[0019] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments; in the following description, specific details such as specific configurations are provided only to help fully understand the embodiments of the present invention. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0021] Unless otherwise specified, the materials, practices and experimental equipment involved in the implementation cases of the present invention are all in line with commercially available products in the relevant chemical and biotechnology fields.

[0022] Example 1 The raw material tank 1 is connected to the anaerobic fermentation acid production tank 3 through the feed pump 2, so as to add the fermentation substrate into the anaerobic fermentation acid production tank 3 through the raw material tank 1; the agitator 4 is installed on the top of the anaerobic fermentation acid production tank 3, and the stirring part of the agitator 4 extends into the anaerobic fermentation acid production tank 3 to mix the kitchen slurry and the inoculum; the circulation port at the upper end of the side wall of the anaerobic fermentation acid production tank 3 is connected to the circulation port at the bottom of the electrocatalytic reaction tank 5 through a circulation pump, and the upper circulation port of the electrocatalytic reaction tank 5 is connected to the circulation port at the lower end of the side wall of the anaerobic fermentation acid production tank 3 through a circulation pump 10, so as to form a closed cycle; the inside of the electrocatalytic reaction tank 5 is provided with an electrode plate 6, and the top is provided with a power supply 8 connected to the electrode plate 6, and the upper part of the catalytic electrode plate 6 is provided with an inclined plate separator 7 and a discharge port 9; the electrocatalytic reaction tank 5 is connected to the finished product tank 11 through the discharge port 9.

[0023] Example 2 A method for preparing a carbon source and efficiently removing ammonia nitrogen from kitchen waste, the specific steps are as follows: S1, the food slurry stored in the raw material tank 1 enters the anaerobic fermentation acid production tank 3 through the feed pump 2, and is fully mixed with the inoculated sludge in the anaerobic fermentation acid production tank 3, and then fermented under anaerobic conditions, and the macromolecular organic matter in the food slurry is hydrolyzed and converted into small molecular organic acids, CO2 and ammonia nitrogen and other substances; S2. During the anaerobic fermentation process, the fermentation mixture circulates between the anaerobic acid production fermentation tank 3 and the electrocatalytic reaction tank 5, and the Cl in the kitchen slurry is converted into - Conversion to ClO - It reacts with Cl2 and ammonia nitrogen to generate nitrogen gas, and at the same time strengthens the cell wall breaking of kitchen utensils, further promoting their acid production; S3, the electrocatalytic system is of upflow type, and the upper inclined plate separator separates the solid and the liquid. After the anaerobic fermentation is completed, the fermentation liquid enters the finished product tank 11 through the discharge port 9 for standby use.

[0024] Preferably, in the continuous flow operation mode of the method, the organic load of the kitchen slurry is 10-30 gVS / L, the hydraulic retention time is between 4-12 days; the system temperature is controlled between 25-37°C, and the pH value is not adjusted during operation and is stable between 5.0-6.5; Preferably, Cl in the kitchen slurry - The concentration is not less than 2000 mg / L, Cl - ClO produced in the electrocatalytic system - and Cl2 to strengthen cell wall disruption, increase acid production and achieve efficient nitrogen removal, with a salt content of no less than 6000 mg / L; Preferably, the voltage of the electrocatalytic system is controlled between 5-7 V and the current density is between 40-60 mA / cm 2 ; Preferably, the residence time of the mixed solution in the electrocatalytic system is about 60 min, of which 50% is the electrocatalytic time and 50% is the ClO - and Cl2 buffer decay time.

[0025] Example 3 The food waste and inoculated anaerobic sludge used in this example were both taken from the Dongcun Comprehensive Treatment Plant in Beijing; the food waste was crushed, homogenized, and boiled to extract oil before being used as an anaerobic fermentation acid production substrate, and the inoculated sludge was allowed to settle for 3 days and the lower layer was taken for standby use. The physical and chemical properties of the food waste slurry and the inoculated sludge are shown in Table 1:

[0026] The food slurry and inoculated sludge are transported to the anaerobic fermentation acid production tank by the feed pump. Nitrogen is introduced into the device for 10 minutes to ensure the anaerobic environment and to keep it sealed. Then, efficient anaerobic fermentation is carried out. During the reaction, the organic load is stabilized at about 24 gvs / L, and the food slurry and sludge inoculation ratio (VS) is 2:1. After a certain period of anaerobic fermentation acid production reaction, the acid-producing mixed liquid circulates into the electrocatalytic system, and the power supply is turned on at the same time. A voltage of 5-7 V is continuously applied to the electric fermentation device, and the mixed liquid stays in the electrocatalytic device for about 60 minutes. According to the test, the changes in SCOD and VFAs concentrations, ammonia nitrogen content and VFAs component proportions during anaerobic fermentation are as follows: Figure 2 , Figure 3 and Figure 4 shown.

[0027] During the anaerobic fermentation 0-4 days, the VFAs content increased from 4107.98 to 16731.21 mgCOD / L, and the VFAs conversion rate was 61.75%. The ammonia nitrogen content increased from 976.35 to 1480.54 mg / L on the first day of anaerobic fermentation, and gradually decreased to 88.66 mg / L during the subsequent reaction time. The ammonia nitrogen degradation rate was 94.01%. As the fermentation time increased, the proportion of acetic acid in the VFAs components increased from 24% to 37%, and the proportion of butyric acid decreased from 62% to 42%.

[0028] Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner, but they will not deviate from the inventive concept of the present application or exceed the scope defined by the attached claims.

Claims

1. A device for preparing carbon source from kitchen waste and removing ammonia nitrogen efficiently and synergistically, characterized in that: The device comprises an acid generating system and an electrocatalytic system, one end of the acid generating system is connected to a raw material tank (1), one end of the electrocatalytic system is connected to a finished product tank (11), and the acid generating system and the electrocatalytic system are connected via a circulation system.

2. The device for preparing carbon source and efficiently removing ammonia nitrogen from kitchenware according to claim 1, characterized in that: The acid production system comprises an anaerobic fermentation acid production tank (3) and a stirrer (4), wherein the stirring portion of the stirrer (4) extends into the interior of the anaerobic fermentation acid production tank (3); the electrocatalytic system comprises an electrocatalytic reaction tank (5), wherein an electrode plate (6) is provided inside the electrocatalytic reaction tank (5).

3. The device for preparing carbon source and efficiently removing ammonia nitrogen from kitchenware according to claim 2, characterized in that: The circulation system comprises a pipeline forming a closed circulation between the anaerobic fermentation acid production tank (3) and the electrocatalytic reaction tank (5), a circulation pump, and a circulation port arranged on the anaerobic fermentation acid production tank (3) or the electrocatalytic reaction tank (5).

4. The device for preparing carbon source and efficiently removing ammonia nitrogen from kitchenware according to claim 3, characterized in that: An inclined plate separator (7) and a discharge port (9) are provided on the upper portion of the electrode plate (6), and the electrocatalytic reaction tank (5) is connected to the finished product tank (11) via the discharge port (9).

5. A method for preparing carbon source and efficiently removing ammonia nitrogen from kitchen waste using the device according to claim 4, characterized in that: The specific steps include: S1, the crushed and homogenized food waste slurry is pumped into the anaerobic fermentation acid production tank (3) through the feed inlet by a screw pump, and the materials are fully mixed under the action of the stirrer (4), thereby realizing the food waste acid production process; S2, the circulation port at the upper end of the side wall of the anaerobic fermentation acid production tank (3) is connected to the circulation port at the bottom of the electrocatalytic reaction tank (5) through a circulation pump, and the upper circulation port of the electrocatalytic reaction tank (5) is connected to the bottom of the anaerobic fermentation acid production tank (3), forming a closed loop to allow the fermentation mixed liquid to circulate; S3. The electrocatalytic system is of upflow type. The upper inclined plate separator (7) separates the solid and liquid and then discharges the material through the discharge trough.

6. The method according to claim 5, characterized in that The steps are specifically as follows: S1, the food waste slurry stored in the raw material tank (1) enters the anaerobic fermentation acid production tank (3) through the feed pump (2), is fully mixed with the inoculated sludge in the anaerobic fermentation acid production tank (3), and is fermented under anaerobic conditions, so that the macromolecular organic matter in the food waste slurry is hydrolyzed and converted into small molecular organic acids, CO2, ammonia nitrogen and other substances; S2. During the anaerobic fermentation process, the fermentation mixture circulates between the anaerobic acid production fermentation tank (3) and the electrocatalytic reaction tank (5), and the Cl in the kitchen slurry is converted into - Conversion to ClO - It reacts with Cl2 and ammonia nitrogen to generate nitrogen gas, and at the same time strengthens the cell wall breaking of kitchen utensils, further promoting their acid production; S3. The electrocatalytic system is of upflow type. After the upper inclined plate separator (7) separates the solid and the liquid, the fermentation liquid enters the finished product tank (11) through the discharge port (9) for standby use.

7. The method according to claim 6, characterized in that Under the continuous flow operation mode, the organic load of the food slurry is between 10-30 gVS / L, and the hydraulic retention time is between 4-12 d; the system temperature is controlled between 25-37°C, and the pH value is not adjusted during operation and is stable between 5.0-6.

5.

8. The method according to claim 6, characterized in that Cl in kitchen slurry - The concentration is not less than 2000 mg / L, Cl - ClO produced in the electrocatalytic system - And Cl2 strengthens cell wall breaking to increase acid production and achieve efficient nitrogen removal, with the salt content not less than 6000 mg / L.

9. The method according to claim 6, characterized in that The voltage of the electrocatalytic system was controlled between 5-7 V and the current density was between 40-60 mA / cm 2 .

10. The method according to claim 6, characterized in that The residence time of the mixed solution in the electrocatalytic system is about 60 min, of which 50% is electrocatalytic time and 50% is ClO - and Cl2 buffer decay time.

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