Method and system for promoting hydrolytic acidification of organic wastewater to produce acid

Abstract

The invention discloses a method and a system for promoting hydrolytic acidification of organic wastewater to produce acid, and the method comprises the following steps: firstly, adjusting COD (Chemical Oxygen Demand) and pH (Potential of Hydrogen) of sewage in an adjusting tank to meet the requirements of enzyme treatment; then the sewage enters the enzyme treatment tank after being heated by the heater, the degradability of the sewage is improved through enzyme treatment, then the sewage enters the anaerobic hydrolytic acidification tank through the temperature controller, and hydrolytic acidification is carried out under the anaerobic condition under the action of anaerobic microorganisms to produce volatile acid. The method is realized through a system comprising an adjusting tank, an enzyme treatment tank, a hydrolytic acidification tank, a heater, a temperature controller, an enzyme adding device, a chemical adding device and stirring devices of an enzyme pretreatment area and a hydrolytic acidification area. Rapid degradation of organic matters in wastewater can be effectively promoted, and the acid production efficiency of sewage is improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic wastewater treatment, and in particular to a method and system for promoting acid production by hydrolysis and acidification of organic wastewater. Background Art

[0002] my country has implemented stricter emission standards for total nitrogen (TN) emissions from sewage treatment plants. The emission standards implemented in some areas are lower than 10 mg / L. However, the low influent carbon / nitrogen (C / N) ratio limits the denitrification efficiency, so a large amount of external carbon source needs to be added to reduce it. However, the low influent carbon / nitrogen (C / N) ratio limits the denitrification efficiency, which usually requires a large amount of external carbon to reduce TN. Generally, sewage treatment plants use external carbon sources such as methanol and sodium acetate to enhance the denitrification effect during operation, which undoubtedly increases operating costs. Industrial wastewater as an external carbon source can effectively save resources and reduce the cost of factory wastewater treatment. Using more economical raw materials such as organic waste (such as food waste, sewage sludge, and landfill leachate) to produce VFA fermentation liquid for acid production as an external carbon source for sewage treatment plants, and implementing "waste treatment with waste" can help minimize waste treatment and achieve the goal of energy conservation and carbon reduction.

[0003] During anaerobic fermentation, VFA is easily utilized by microorganisms to generate CH4 and CO2. Continuous acidogenic fermentation can be achieved by controlling operating parameters and sludge properties to promote hydrolysis and acidification while preventing methane production. Hydraulic retention time (HRT) and pH value are considered to be one of the most influential operating conditions on the functional properties of biological processes and are usually used as control factors to promote the desired fermentation process. The carbohydrates and organic matter contained in the wastewater can provide a good carbon source for denitrifying bacteria, thereby increasing the denitrification rate of the system. However, due to the large amount of heterogeneity and complex composition of industrial wastewater, it is necessary to consider whether microorganisms adapted to the specific environmental conditions of industrial wastewater can reproduce and grow in the actual complex wastewater environment. For organic wastewater that is difficult to degrade, such as landfill leachate, the concentration of organic pollutants is high, the composition is complex, and the biodegradability is poor. Conventional biodegradation methods are difficult to achieve ideal treatment effects, so they have become the focus and difficulty of research in the field of water treatment. When using coagulation, membrane treatment, adsorption, electro-Fenton and other methods for treatment. It is easy to cause secondary pollution and increase the treatment cost.

[0004] Chinese patent CN116514278A discloses a method for producing biogas by anaerobic fermentation of high-concentration organic wastewater. The method uses modified biochar to treat high-concentration organic wastewater. After the biochar adsorbs the high-concentration organic wastewater to reduce the concentration, anaerobic fermentation is performed to achieve the treatment of high-concentration organic wastewater. This method fails to effectively utilize the carbon resources of organic wastewater and brings about the problem of secondary treatment. Chinese patent CN118666416A discloses a biological denitrification system and method for high-carbon-nitrogen ratio landfill leachate. The method is implemented by a system having an anaerobic digestion reactor, a synchronous short-range nitrification / denitrification reactor, an anaerobic ammonium oxidation reactor, a nitrification / denitrification reactor and an ultrafiltration device, and only has a good treatment effect on high-carbon-nitrogen ratio wastewater. The process flow is long and the operation is complicated. Chinese patent CN117142647A discloses a method and device for combined treatment of landfill leachate and domestic sewage. The method is implemented by a device comprising a domestic sewage treatment system (1), a landfill leachate treatment system (2), a combined treatment system (3) and a sludge treatment system (4). Domestic sewage is treated by the domestic sewage treatment system to remove organic matter and phosphate, and ammonia nitrogen is retained; landfill leachate is treated by the landfill leachate treatment system to remove organic matter and phosphate, and ammonia nitrogen is converted into nitrite nitrogen. After entering the combined treatment system, nitrogen is first removed by an anaerobic ammonia oxidation unit, and then denitrified by an AO-MBR enhanced denitrification unit using the hydrolyzate produced by the sludge treatment system as a carbon source to further remove nitrogen and organic matter. The process flow of this method is extremely complex, the cost is high, and the treatment effect on difficult-to-degrade organic wastewater is poor. In summary, it is very necessary to develop a method and system that can efficiently and economically promote the hydrolysis and acidification of organic wastewater in a practical environment. Summary of the invention

[0005] The object of the present invention is to provide a method and system for promoting the hydrolysis and acidification of organic wastewater to produce acid, so as to solve the problems existing in the prior art mentioned above.

[0006] According to a first aspect of the present invention, a method for promoting acid production by hydrolysis of organic wastewater comprises the following steps: Step 100: The sewage enters the regulating tank to adjust the COD and pH of the sewage to meet the requirements of enzyme treatment; Step 200: The conditioned sewage is heated to a temperature suitable for enzyme pretreatment by a heater, and then enters an enzyme treatment tank. A certain amount of enzyme is added to the enzyme treatment tank through an enzyme adding device according to the COD content of the sewage, and the refractory organic matter is degraded by the enzyme within a certain period of time, thereby improving the biodegradability of the sewage; Step 300: After the treatment in step 200, the wastewater completes the degradation of the difficult-to-degrade organic matter, and enters the anaerobic hydrolysis acidification tank after reaching the appropriate temperature through the temperature controller, and undergoes hydrolysis and acidification to produce volatile acids under the action of anaerobic microorganisms. The anaerobic acid production of the wastewater is optimized by adjusting the temperature, pH, and HRT. The treated wastewater enters the subsequent treatment unit through a pipeline for carbon source utilization.

[0007] Enzymes are used to treat the difficult-to-degrade organic matter in sewage to achieve the degradation of the difficult-to-degrade organic matter.

[0008] The anaerobic fermentation acid production process of sewage is optimized by adjusting temperature, pH and HRT to maximize the acid production of sewage.

[0009] In one embodiment, the COD range of the sewage in the regulating tank is 2000-60000 mg / L, and the pH range is 4-8.

[0010] In one embodiment, the enzyme pretreatment temperature is 25-75°C to exert the activity of the enzyme and degrade organic matter in the sewage.

[0011] In one embodiment, the enzyme is a complex enzyme, which is one or more of lipase, protease, amylase, and cellulase.

[0012] In one embodiment, the enzyme treatment time is 1-4 h.

[0013] In one embodiment, the temperature of anaerobic fermentation and acid production is 25-55° C., at which the activity of anaerobic microorganisms is exerted to produce acid through anaerobic digestion.

[0014] In one embodiment, the pH of the anaerobic fermentation acid production is 5-7, and the anaerobic microbial acid production process is regulated at this pH to improve the acid production efficiency.

[0015] In one embodiment, the pH of the anaerobic fermentation acid production is 5-7 and the HRT is 2-72h. By adjusting the HRT, the anaerobic sludge load is optimized and the acid production efficiency is improved.

[0016] In one embodiment, the anaerobic sludge in the anaerobic treatment is anaerobic sludge that has been treated to have no methane production function and is only subjected to the hydrolysis and acidification stage, and performs the acid production process of organic matter degradation to achieve carbon source utilization.

[0017] According to another aspect of the present invention, the present invention also provides a system for promoting acid production by hydrolysis and acidification of organic wastewater, comprising: Equalizing tank, enzyme treatment tank, hydrolysis acidification tank, heater, enzyme adding device, temperature controller, dosing device and stirring device.

[0018] The regulating tank comprises a sewage inlet and a sewage outlet; the sewage outlet is arranged on one side of the upper part of the regulating tank and is connected to the heater through a pipeline.

[0019] The enzyme treatment tank comprises a sewage inlet, a sewage outlet, an enzyme inlet, an insulation layer, and a stirring device; the sewage outlet is connected to a temperature controller through a pipeline, the enzyme inlet is connected to the enzyme device through a pipeline, and the stirring device is located on the top of the enzyme treatment tank.

[0020] The hydrolysis acidification tank comprises a sewage inlet, a sewage outlet, a dosing inlet, an exhaust port, a mud outlet, an insulation layer, a stirring device and a pH meter; the sewage inlet is connected to a temperature controller through a pipeline; the dosing inlet is located at one side of the top of the hydrolysis acidification tank and is connected to the dosing device through a pipeline; the exhaust port is located at one side of the top of the hydrolysis acidification tank; the mud outlet is located at the bottom of the hydrolysis acidification tank; the pH meter is located at one side of the inside of the hydrolysis acidification tank and is connected to the dosing device.

[0021] In one embodiment, the distance from the top of the stirring device of the enzyme treatment tank and the hydrolysis acidification tank to the bottom of the tank body is 10-100 cm.

[0022] In one embodiment, the insulation layer is located outside the enzyme treatment tank and the hydrolysis acidification tank, and the thickness of the insulation layer is 0.05-0.15 m; the insulation layer material is one or more of polyurethane, polystyrene, polyvinyl chloride, and phenolic resin.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The process is simple, and the use of compound enzymes can improve the biodegradability of sewage without the use of chemical agents, and there is no secondary pollution; (2) Anaerobic fermentation of the enzyme and treated wastewater produces acid. By adjusting the acid production conditions and optimizing the acid production process, anaerobic fermentation liquid rich in volatile acids can be obtained as an external carbon source to enter the subsequent treatment unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a system for promoting acid production by hydrolysis and acidification of organic wastewater in an embodiment of the present invention.

[0025] Reference numerals: 1 Regulating tank 2 Enzyme treatment tank 3 Hydrolysis acidification tank 4 Heater 5 Enzyme adding device 6 Temperature controller 7 Dosing device 8 Stirring device 9 pH meter 101 sewage inlet 102 Sewage outlet 201 Sewage inlet 202 Sewage outlet 203 Dosing inlet 204 Insulation layer 301 Sewage inlet 302 Sewage outlet 303 Dosing inlet 304 exhaust port 305 mud discharge port 306 Insulation layer DETAILED DESCRIPTION

[0026] The following will be combined with the attached Figure 1 The present invention is further described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] like Figure 1 As shown, according to one aspect of the present invention, the present invention provides a system for promoting the hydrolysis and acidification of organic wastewater to produce acid, which includes a membrane bioreactor 1 regulating tank, 2 enzyme treatment tank, 3 hydrolysis acidification tank, 4 heater, 5 enzyme adding device, 6 temperature controller, 7 dosing device and 8 stirring device. In the regulating tank 1, sewage enters the regulating tank 1, and the COD and pH of the sewage are adjusted to meet the requirements of enzyme treatment. After the regulated sewage is heated to a temperature suitable for enzyme treatment by the heater 4, it enters the enzyme treatment tank 2 through a pipeline. In the enzyme treatment tank 2, a certain enzyme is added through the enzyme adding device 5, and the biodegradability of the sewage is improved after a period of enzyme treatment; the sewage after enzyme pretreatment is adjusted in temperature by the temperature controller 6 and enters the hydrolysis acidification tank for anaerobic fermentation and acid production, and a certain amount of acid or alkali is added through the dosing device 7 to maintain the optimal pH of anaerobic fermentation and acid production, thereby improving the efficiency of sewage acid production.

[0028] The following describes each of them separately.

[0029] like Figure 1 The regulating tank 1 shown in the figure is provided with a sewage inlet 101 on one side of the external tail end, and a sewage outlet 102 on one side of the external top end, which are connected to the heater 4 through a pipeline.

[0030] A sewage inlet 201 is provided on one side of the external tail end of the enzyme treatment tank 2, which is connected to the heater 4 through a pipe; a sewage outlet 202 is provided on one side of the external top end, which is connected to the temperature controller 6 through a pipe; an enzyme addition inlet 203 is provided on one side of the top end, which is connected to the enzyme addition device 5 through a pipe; an insulation layer 204 is provided on the outside of the enzyme treatment tank 2, the thickness of the insulation layer is 0.05-0.15 m, and a stirring device 8-1 is provided inside; A sewage inlet 301 is provided on one side of the external tail end of the hydrolysis acidification tank 3, which is connected to the temperature controller 6 through a pipeline; a sewage outlet 302 is provided on one side of the external top end; a dosing inlet 303 is provided on one side of the top end, which is connected to the dosing device 7 through a dosing pipeline; an exhaust port 304 is provided on one side of the top, and a mud discharge port 305 is provided on the bottom end; an insulation layer 306 is provided on the outside, and the thickness of the insulation layer is 0.05-0.15 m, a stirring device 8-2 is provided on the internal top end, and a pH meter 9 is provided on one side of the inside and connected to the dosing device 7.

[0031] The heater 4 is connected to the hydrolysis tank 1 and the enzyme treatment tank 2 through pipelines, and heats the sewage flowing out of the hydrolysis tank and about to enter the enzyme treatment tank 2 to meet the enzyme treatment temperature requirement.

[0032] The temperature controller 6 is connected to the enzyme treatment tank 2 and the hydrolysis acidification tank 3 through pipelines, and adjusts the temperature of the sewage flowing out of the enzyme treatment tank and about to enter the hydrolysis acidification tank 3 to meet the temperature requirement of anaerobic fermentation.

[0033] According to another aspect of the present invention, the present invention provides a method for promoting acid production by hydrolysis and acidification of organic wastewater, which adopts a system for promoting acid production by hydrolysis and acidification of organic wastewater, comprising the following steps: Step 100: allowing the sewage containing refractory organic matter to enter the regulating tank 1 through the sewage inlet 101 to adjust the COD and pH; Step 200: The conditioned sewage is heated to a certain temperature by the heater 4 and then enters the enzyme treatment tank 2 through the sewage inlet 201, and a certain amount of enzyme is added to the enzyme treatment tank 2 by the enzyme adding device 5, and stays for a certain time to complete the degradation of organic matter; Step 300: After the sewage is treated in the enzyme treatment tank 2 and the temperature is adjusted by the temperature controller 6, it enters the hydrolysis acidification tank 3 through the sewage inlet 301, and is hydrolyzed and acidified to produce volatile acid under the action of anaerobic microorganisms in the anaerobic sludge. The pH change is detected by the pH meter 9, and the pH is adjusted by the dosing device 7. At the same time, the HRT is adjusted to optimize the acid production. The generated gas is discharged after being treated to meet the standards through the exhaust port 304, and the remaining sludge is discharged through the sludge discharge port 305. The treated sewage enters the subsequent treatment unit through the pipeline from the sewage outlet 302 for carbon source utilization.

[0034] In summary, the present invention divides the process of promoting the hydrolysis and acidification of organic wastewater into three stages, namely, the first stage is to adjust the COD and pH of the sewage in the regulating tank to meet the requirements of enzyme treatment; the second stage is to improve the degradability of the sewage by enzyme treatment in the enzyme treatment tank; the third stage is to hydrolyze and acidify to produce volatile acids through the action of anaerobic microorganisms under anaerobic conditions, which can improve the degradability of the sewage and promote the acid production efficiency of the sewage without adding external chemical agents and without secondary pollution. Example

[0035] Taking garbage leachate as an example, the implementation process of the present invention is specifically described below by using α-amylase to treat the garbage leachate for anaerobic fermentation to produce acid.

[0036] Contains 50m3 of refractory organic matter 3 The landfill leachate enters the regulating tank 1 through the feed port 101 at 40 L / min for COD and pH adjustment. After adjustment, the COD of the landfill leachate is 6870, the volatile acid content is 1314.507 mg / L, and the pH is 5.74. After being heated to 50°C by the heater, it enters the enzyme treatment tank 2. The enzyme adding device adds 200g enzyme / m 3 α-amylase is added to the sewage and treated for 5 hours. The sewage treated by enzyme is adjusted to 35°C by the temperature controller 6 and then flows into the hydrolysis acidification tank 3. The pH is adjusted to 6 by the dosing device 7 through the pH meter monitoring. Under the action of anaerobic hydrolysis acidification microorganisms, fermentation is carried out to produce volatile acid. The maximum acid production stage is reached when the HRT is 18 hours. At this time, the volatile acid content is 2298.457, and the volatile acid concentration is increased by 74.85%. The treated sewage enters the subsequent treatment unit through the pipeline from the sewage outlet 302 for carbon source utilization. Example

[0037] Taking garbage leachate as an example, the implementation process of the present invention is specifically described below by treating the garbage leachate with protease to carry out anaerobic fermentation to produce acid.

[0038] Contains 50m3 of refractory organic matter 3 The landfill leachate enters the regulating tank 1 through the feed port 101 at 40 L / min for COD and pH adjustment. After adjustment, the COD of the landfill leachate is 6827.6, the volatile acid content is 1327.671 mg / L, and the pH is 5.86. After being heated to 45°C by the heater, it enters the enzyme treatment tank 2. The enzyme adding device adds 200g enzyme / m 3 α-amylase is added to the sewage and treated for 5 hours. The sewage treated by enzyme is adjusted to 35°C by the temperature controller 6 and then flows into the hydrolysis acidification tank 3. The pH is adjusted to 6 by the dosing device 7 through the pH meter monitoring. Under the action of anaerobic hydrolysis acidification microorganisms, fermentation is carried out to produce volatile acid. The maximum acid production stage is reached when the HRT is 24 hours. At this time, the volatile acid content is 2342.703, and the volatile acid concentration is increased by 76.45%. The treated sewage enters the subsequent treatment unit through the pipeline from the sewage outlet 302 for carbon source utilization.

Claims

1. A method for promoting acid production by hydrolysis and acidification of organic wastewater, characterized in that: The following steps are involved: Step 100: The sewage enters the regulating tank for COD and pH adjustment; Step 200: the conditioned sewage is heated to a certain temperature by a heater and then enters an enzyme treatment tank, a certain amount of enzyme is added to the enzyme treatment tank by an enzyme adding device, and the enzyme stays for a certain period of time to complete the degradation of organic matter and improve the biodegradability of the sewage; Step 300: The sewage treated in step 200 enters the anaerobic hydrolysis acidification tank through a temperature controller, and is hydrolyzed and acidified to produce volatile acid under the action of anaerobic microorganisms in the anaerobic sludge. The acid production is optimized by controlling the temperature, pH, and HRT. The treated sewage enters the subsequent treatment unit through a pipeline for carbon source utilization.

2. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The COD range of the sewage in the regulating tank is 2000-60000 mg / L, and the pH range is 4-8.

3. The pretreatment method for promoting hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The temperature in step 200 is 25-75°C.

4. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The enzyme in step 200 is one or more of lipase, protease, amylase and cellulase.

5. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The time described in step 200 is 1-4 hours.

6. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The temperature in step 300 is 25-55°C.

7. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The pH in step 300 is 4-8.

8. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The HRT described in step 300 is 2-72h.

9. The method for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 1, characterized in that: The anaerobic sludge in step 200 is the anaerobic sludge which has been treated to have no methane production function and has only undergone the hydrolysis and acidification stage.

10. A system for promoting acid production by hydrolysis and acidification of organic wastewater, characterized in that: include: A regulating tank (1), an enzyme treatment tank (2), a hydrolysis acidification tank (3), a heater (4), an enzyme adding device (5), a temperature controller (6), a drug adding device (7) and a stirring device (8); The regulating tank (1) comprises a sewage inlet (101) and a sewage outlet (102); the sewage outlet (102) is arranged on one side of the upper part of the regulating tank and is connected to the heater (4) through a pipeline; The enzyme treatment tank (2) comprises a sewage inlet (201), a sewage outlet (202), an enzyme addition inlet (203), an insulation layer (204), and a stirring device 8-1; the sewage outlet (2) is connected to a temperature controller (6) via a pipeline, the enzyme addition inlet (203) is connected to an enzyme addition device (5) via a pipeline, and the stirring device (8-1) is located at the top of the enzyme treatment tank (2); the hydrolysis acidification tank (3) comprises a sewage inlet (301), a sewage outlet (302), a drug addition inlet (303), an exhaust port (304), an exhaust port (305), and a water discharge port (5). A mud outlet (305), an insulation layer (306), a stirring device (8-2) and a pH meter (9); the sewage inlet (301) is connected to a temperature controller (6) via a pipeline; the dosing inlet (303) is located on one side of the top of the hydrolysis acidification tank (3) and is connected to the dosing device (7) via a pipeline; the exhaust port (304) is located on one side of the top of the hydrolysis acidification tank (3); the mud outlet (305) is located at the bottom of the hydrolysis acidification tank (3); and the pH meter (9) is located on one side of the inside of the hydrolysis acidification tank (3) and is connected to the dosing device (7).

11. The system for promoting acid production by hydrolysis and acidification of organic wastewater according to claim 10, characterized in that: The distance from the top of the stirring device (8) of the enzyme treatment tank (2) and the hydrolysis acidification tank (3) to the bottom of the tank body is 10-100 cm.

12. The system for promoting acidification and hydrolysis of organic wastewater according to claim 10, characterized in that: The insulation layer is located outside the enzyme treatment tank (2) and the hydrolysis acidification tank (3), and the thickness of the insulation layer is 0.05-0.15 m; the insulation layer material is one or more of polyurethane, polystyrene, polyvinyl chloride, and phenolic resin.

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