Organic wastewater advanced treatment method and treatment device based on advanced oxidation coupling coagulation denitrification method

Abstract

The invention discloses an advanced organic wastewater treatment method and treatment device based on an advanced oxidation coupling coagulation denitrification method, and relates to the technical field of landfill leachate treatment, kitchen waste treatment, kitchen garbage treatment and the like, the treatment device comprises a coagulation tank unit, a flocculation tank unit, an air floatation and filter tank unit, an ozone catalysis unit and an activated carbon filter unit which are connected in sequence, the ozone generation unit and the tail gas decomposition unit are connected with the ozone catalysis unit. According to the invention, a traditional nanofiltration membrane advanced treatment process in the industry is replaced by an advanced treatment process of coagulation, flocculation, air floatation, filtration, ozone catalysis and activated carbon filtration, so that the generation of a concentrated solution is avoided; the defect that the biogas yield of an anaerobic digestion system is reduced due to the fact that the sulfate-containing concentrated solution flows back to the anaerobic digestion system of the landfill leachate treatment plant or the kitchen waste treatment plant is overcome, the load of a biogas desulfurization system of the landfill leachate treatment plant and the kitchen waste treatment plant is reduced, and the consumption cost of the concentrated solution is greatly reduced.

Description

Technical Field

[0001] This invention relates to the technical fields of landfill leachate treatment, kitchen waste treatment, and food waste treatment. Specifically, it relates to a method and device for deep treatment of organic wastewater based on advanced oxidation coupled coagulation denitrification. This method and device are used to treat organic wastewater such as landfill leachate, kitchen waste wastewater, and food waste wastewater. Background Technology

[0002] The core treatment system in the food waste treatment plant industry is the anaerobic digestion system, which uses anaerobic microorganisms to degrade the organic matter in food waste into methane (the main component of biogas) and carbon dioxide. The anaerobic reaction process takes place in a sealed container and is divided into two stages: The first stage is the hydrolysis and acidification stage, where fermentative bacteria first decompose high-molecular-weight organic matter into small-molecule soluble organic matter, such as sugars, amino acids, and fatty acids. Then, under the action of hydrolytic enzymes secreted by microorganisms (lipases, proteases, cellulases, amylases, etc.), these are hydrolyzed into monomers, such as cellulose becoming glucose and proteins becoming polypeptides or amino acids. Then, hydrogen-producing and acid-producing bacteria convert these products into volatile organic fatty acids such as acetic acid, propionic acid, and butyric acid, while producing carbon dioxide and hydrogen. The second stage is the methanogenesis stage, where methanogenic bacteria convert acetic acid into carbon dioxide and methane, or use hydrogen to reduce carbon dioxide to produce methane.

[0003] Currently, anaerobic digestion combined with MBR and N+ / RO has become the mainstream process for treating landfill leachate and waste incineration plant leachate in my country. However, this process produces 25% to 35% concentrate. In recent years, some new methods for treating landfill leachate concentrate have emerged both domestically and internationally, such as the reflow incinerator method, advanced oxidation methods, and evaporation methods. However, concentrate treatment remains a major challenge for the landfill leachate treatment industry.

[0004] Due to increasingly stringent emission standards for treated organic wastewater such as landfill leachate and kitchen waste water, many such wastewater treatment systems typically employ a combination of biological treatment, ultrafiltration, and nanofiltration for advanced treatment. This means that advanced treatment using nanofiltration membrane devices is necessary to meet emission standards. However, advanced treatment using nanofiltration membrane devices generates 15%–20% concentrate, which can have COD concentrations as high as several thousand mg / L and exhibits extremely poor biodegradability. The industry typically handles this concentrate either by outsourcing disposal or by recirculating it to the plant's anaerobic digestion system. However, the cost of outsourcing disposal is as high as several hundred yuan per ton. Although returning the waste to the anaerobic digestion system does not incur direct costs, long-term return to the anaerobic digestion system will cause sulfate in the concentrate to accumulate in the system, promoting the enrichment of sulfate-reducing bacteria. Sulfate-reducing bacteria compete with methanogens for substrates, which will inhibit methanogens. This will not only greatly reduce the biogas yield, but also lower the methane concentration and increase the sulfur content in the biogas, increasing the difficulty of subsequent biogas desulfurization and the load on the biogas desulfurization unit. This will greatly reduce the overall economic value of biogas by-products from landfill leachate treatment plants and food waste treatment plants, thus weakening the economic benefits of food waste treatment plants. Summary of the Invention

[0005] The purpose of this invention is to provide a method and device for deep treatment of organic wastewater based on advanced oxidation coupled coagulation denitrification. By adopting a deep treatment process of coagulation + flocculation + flotation + filtration + ozone catalysis + activated carbon filtration, it replaces the traditional nanofiltration membrane deep treatment process in the industry. This not only avoids the generation of concentrated liquid, but also avoids the disadvantage of reduced biogas production in anaerobic digestion systems caused by the return of sulfate-containing concentrated liquid to the anaerobic digestion systems of landfill leachate treatment plants or food waste treatment plants. It also reduces the load on the biogas desulfurization systems of landfill leachate treatment plants and food waste treatment plants, and greatly reduces the cost of concentrated liquid disposal.

[0006] To achieve the objective of this invention, the technical solution adopted is: a method for deep treatment of organic wastewater based on advanced oxidation coupled with coagulation denitrification, comprising the following steps: Step S1: Send the kitchen waste wastewater or landfill leachate to be treated into the coagulation tank unit, add coagulant into the coagulation tank unit, mix the kitchen waste wastewater or landfill leachate with the coagulant and then send it into the flocculation tank unit. Step S2: Add flocculant to the flocculation tank, mix the coagulated liquid sent to the flocculation tank unit in step S1 with the flocculant, and send the supernatant to the air flotation + filter unit after sedimentation. Step S3: The supernatant undergoes flotation and filtration in the flotation + filter unit, and the filtered clear liquid is sent to the ozone catalysis unit. Step S4: Ozone is introduced into the ozone catalytic unit, and the COD in the clear liquid entering the ozone catalytic unit is removed by the catalysis of ozone. Step S5: The ozone-catalyzed solution from step S4 is sent to an activated carbon filter unit for filtration to reduce the color intensity of the solution.

[0007] Furthermore, the coagulant is ferric chloride, and the flocculant is polyacrylamide.

[0008] Furthermore, in step S1, the leachate from the kitchen waste is mixed with the coagulant and then left to stand for 3 to 8 minutes.

[0009] Furthermore, in step S2, the coagulated liquid and flocculant in the flocculation tank unit are mixed and then left to stand for 10 to 20 minutes.

[0010] Furthermore, in step S3, the time for the supernatant to undergo flotation and filtration in the flotation + filter unit is 20 min to 40 min.

[0011] The treatment device based on the above-mentioned deep treatment method for organic wastewater includes a coagulation tank unit, a flocculation tank unit, an air flotation + filter unit, an ozone catalysis unit and an activated carbon filtration unit connected in sequence, and also includes an ozone generation unit and a tail gas decomposition unit connected to the ozone catalysis unit.

[0012] Furthermore, both the coagulation tank unit and the flocculation tank unit are equipped with a stirrer.

[0013] Furthermore, both the coagulation tank unit and the flocculation tank unit contain multiple agitators.

[0014] Furthermore, the coagulation tank unit, flocculation tank unit, air flotation + filter unit, ozone catalysis unit and activated carbon filter unit all discharge liquid through overflow.

[0015] Furthermore, the coagulation tank unit, flocculation tank unit, air flotation + filter unit, ozone catalysis unit and activated carbon filtration unit are connected in sequence and tightly, and the overflow port height connecting the coagulation tank unit, flocculation tank unit, air flotation + filter unit, ozone catalysis unit and activated carbon filtration unit decreases by 5cm to 10cm in sequence.

[0016] Furthermore, the bottom of each of the coagulation tank unit, flocculation tank unit, air flotation + filter unit, ozone catalysis unit, and activated carbon filter unit is equipped with a sewage discharge pipe.

[0017] The beneficial effects of this invention are: (1) By adopting a deep treatment process of coagulation + flocculation + flotation + filtration + ozone catalysis + activated carbon filtration to replace the traditional nanofiltration membrane deep treatment process in the industry, not only is the generation of concentrate avoided, but also the drawback of reduced biogas production in anaerobic digestion system caused by the return of sulfate-containing concentrate to the anaerobic digestion system of landfill leachate treatment plant or kitchen waste treatment plant is avoided. This reduces the load on the biogas desulfurization system of landfill leachate treatment plant and kitchen waste treatment plant and greatly reduces the cost of concentrate disposal.

[0018] (2) In this invention, the coagulation tank unit, flocculation tank unit, flotation + filter unit, ozone catalysis unit and activated carbon filter unit are connected in sequence and the overflow port height of the coagulation tank unit, flocculation tank unit, flotation + filter unit, ozone catalysis unit and activated carbon filter unit is lowered in sequence, so that each unit overflows to the next unit by gravity after treatment. This unique design can save the energy consumption of each link of wastewater deep treatment and save operating costs.

[0019] (3) This invention eliminates the need for traditional deep treatment units using nanofiltration membranes, which not only achieves deep treatment and compliant discharge of wastewater and leachate from food waste treatment plants, avoiding the generation of concentrate and reducing operating costs, but also improves the stability of the anaerobic digestion system of food waste treatment plants and leachate treatment plants, increases biogas production, and creates economic benefits for food waste treatment plants and leachate treatment plants. Attached Figure Description

[0020] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0021] Figure 1 This is a schematic diagram of an advanced organic wastewater treatment device based on the advanced oxidation-coupled coagulation denitrification method.

[0022] The attached diagram shows the markings and corresponding component names: 1. Coagulation tank unit; 2. Flocculation tank unit; 3. Air flotation + filter unit; 4. Ozone catalysis unit; 5. Ozone generation unit; 6. Tail gas decomposition unit; 7. Activated carbon filtration unit. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] This invention provides a method for advanced treatment of organic wastewater based on advanced oxidation coupled coagulation denitrification, comprising the following steps: Step S1: The kitchen waste wastewater or landfill leachate to be treated is sent into coagulation tank unit 1, and ferric chloride is added to coagulation tank unit 1. Ferric chloride acts as a coagulant, and its acidification can effectively enhance the coagulation effect. The kitchen waste wastewater or landfill leachate in coagulation tank unit 1 is thoroughly mixed with ferric chloride by stirring with the agitator in coagulation tank unit 1. After stirring for 5 minutes, the mixture overflows from the overflow port of coagulation tank unit 1 into flocculation tank unit 2.

[0026] Step S2: Add polyacrylamide to the flocculation tank. Polyacrylamide acts as a flocculant. The liquid medium from the coagulation tank unit 1 is thoroughly mixed with the polyacrylamide by stirring in the agitator in the coagulation tank unit 1. This allows the liquid medium in the flocculation tank unit 2 to flocculate. After stirring for 15 minutes, the supernatant in the flocculation tank unit 2 overflows through the overflow port into the air flotation + filter unit 3. Through coagulation and flocculation, some of the COD and total nitrogen in the kitchen waste wastewater and landfill leachate can be removed.

[0027] Step S3: The supernatant undergoes flotation and filtration in the flotation + filter unit 3 for 30 minutes. The clear liquid after flotation and filtration overflows through the overflow port on the filter of the flotation + filter unit 3 into the ozone catalytic unit 4. Step S4: The ozone generating unit 5 sends the generated ozone into the ozone catalytic unit 4, and after fully contacting the clean liquid entering the ozone catalytic unit 4, further removes the COD in the clean liquid so that the clean liquid meets the emission standard requirements. The remaining ozone in the ozone catalytic unit 4 is removed by sending it into the exhaust gas decomposer. The clean liquid after ozone catalysis overflows into the activated carbon filter unit 7 through the overflow port on the ozone catalytic unit 4. Step S5: The ozone-catalyzed liquid from step S4 is sent to the activated carbon filter unit 7 for filtration. The activated carbon in the activated carbon filter unit 7 can reduce the color of the liquid sent from the ozone catalysis unit 4, so that the liquid meets the emission standards.

[0028] Based on the above-mentioned advanced oxidation coupled coagulation denitrification method for deep treatment of organic wastewater, the present invention also provides an apparatus for advanced treatment of organic wastewater based on the advanced oxidation coupled coagulation denitrification method, such as... Figure 1As shown, the present invention provides an advanced organic wastewater treatment device based on advanced oxidation coupled coagulation denitrification, comprising a coagulation tank unit 1, a flocculation tank unit 2, an air flotation + filter unit 3, an ozone catalytic unit 4, and an activated carbon filter unit 7 connected in sequence. An organic wastewater conveying pipe is connected to the coagulation tank unit 1, allowing the organic wastewater to be treated to be fed into the coagulation tank unit 1 through the pipe. The coagulation tank unit 1 is used to mix the organic wastewater to be treated with a coagulant. The flocculation tank unit 2 is used to mix the coagulated organic wastewater with a flocculant. The air flotation + filter unit 3 is used to perform air flotation and filtration treatment on the supernatant after flocculation treatment. The ozone catalytic unit 4 is used to catalytically oxidize the supernatant after air flotation and filtration treatment, thereby decomposing and removing COD from the supernatant. The activated carbon filter unit 7 is used to filter the ozone-catalyzed supernatant.

[0029] To ensure sufficient ozone in the ozone catalytic unit 4, the advanced organic wastewater treatment device also includes an ozone generating unit 5. The ozone generating unit 5 is an ozone generator, and its outlet is connected to the aeration pipe within the ozone catalytic unit 4 via a pipe, allowing the ozone generated by the generator to fully react with the liquid medium within the ozone catalytic unit 4. To facilitate the decomposition of unreacted ozone within the ozone catalytic unit 4, the top of the ozone catalytic unit 4 is sealed, and a separate tail gas decomposition unit 6 is installed. A pipe connects the upper part of the ozone catalytic unit 4 to the tail gas decomposition unit 6; the tail gas decomposition unit 6 is a tail gas decomposer.

[0030] In this invention, to ensure that the organic wastewater in coagulation tank unit 1 can be fully mixed with the coagulant, and to ensure that the coagulated liquid in flocculation tank unit 2 can be fully mixed with the flocculant, agitators are installed in both coagulation tank unit 1 and flocculation tank unit 2. The agitator includes a stirring motor and a stirring paddle. The stirring motor is mounted on coagulation tank unit 1 and flocculation tank unit 2 through a bracket, while the stirring paddle extends into coagulation tank unit 1 and flocculation tank unit 2. The central shaft of the stirring paddle is fixedly connected to the output shaft of the stirring motor, so that the stirring motor drives the stirring paddle to rotate synchronously while rotating. While rotating, the stirring paddle drives the organic wastewater in coagulation tank unit 1 and flocculation tank unit 2 to be fully agitated, thereby ensuring that the organic wastewater and coagulant are fully mixed.

[0031] Because coagulation tank unit 1 and flocculation tank unit 2 are relatively large, multiple agitators are used in both units to ensure effective mixing. These agitators are arranged in a rectangular array within each unit. When multiple agitators are used in both units, each agitator is driven by an independent motor. In this case, the central axis of each agitator is driven by a separate motor. Of course, when there are multiple agitators in both the coagulation tank unit 1 and the flocculation tank unit 2, the multiple agitators in the coagulation tank unit 1 can be driven by a single agitator motor, and the multiple agitators in the flocculation tank unit 2 can also be driven by a single agitator motor. That is, one agitator in the coagulation tank unit 1 is equipped with an agitator motor, and the central shaft of the agitator's agitator blade is connected to the central shaft of the agitator blades of other agitators in the coagulation tank unit 1 through a chain and sprocket connection or a belt drive. Similarly, one agitator in the flocculation tank unit 2 is equipped with an agitator motor, and the central shaft of the agitator blade is connected to the central shaft of the agitator blades of other agitators in the flocculation tank unit 2 through a chain and sprocket connection or a belt drive.

[0032] In this invention, the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7 all discharge liquid through overflow, so that the precipitates generated by the organic wastewater in the coagulation tank unit 1 during the mixing process with the coagulant can be intercepted as much as possible in the coagulation tank unit 1, the precipitates generated by the organic wastewater in the flocculation tank unit 2 during the mixing process with the flocculant can be intercepted as much as possible in the flocculation tank unit 2, and the particulate aggregates generated by the air flotation in the air flotation + filter unit 3 can be intercepted as much as possible in the filter of the air flotation + filter unit 3.

[0033] In this invention, to simplify the structure of the deep treatment device for organic wastewater, the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7 are sequentially and tightly connected. Adjacent units are separated only by a partition wall. The upper edge of this partition wall serves as the overflow outlet. The height of the partition wall separating the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7 decreases by 5cm to 10cm sequentially. The overflow outlet height on the activated carbon filter unit 7 is 5cm to 10cm lower than the height of the partition wall between the air flotation + filter unit 3 and the ozone catalysis unit 4.

[0034] Of course, the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filtration unit 7 in this invention can also be directly set up within a large cofferdam, with multiple partition walls installed within the cofferdam. This partition walls divide the cofferdam into the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filtration unit 7. While ensuring that the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filtration unit 7 are sequentially connected, the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filtration unit 7 can be connected in sequence. The arrangement of the flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7 within the cofferdam can be adjusted arbitrarily. In this case, in order to ensure the overflow of the coagulation tank unit 1, flocculation tank unit 2, flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7, the height of the partition wall separating the coagulation tank unit 1, flocculation tank unit 2, flotation + filter unit 3, and ozone catalysis unit 4 is reduced by 5cm to 10cm in sequence, and the overflow port height on the activated carbon filter unit 7 is 5cm to 10cm lower than the partition wall height between the flotation + filter unit 3 and the ozone catalysis unit 4.

[0035] To facilitate the discharge of sludge and solid matter from the coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7, and to facilitate the discharge of cleaning wastewater when cleaning is required, a drain pipe is installed at the bottom of each of the following units: coagulation tank unit 1, flocculation tank unit 2, air flotation + filter unit 3, ozone catalysis unit 4, and activated carbon filter unit 7. The drain pipe is equipped with a switch valve.

[0036] Based on the above processing device Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A treatment method of an organic wastewater advanced treatment device based on a high-level oxidation coupled coagulation denitrification method, characterized by, Includes the following steps: Step S1: Send the kitchen waste wastewater or landfill leachate to be treated into the coagulation tank unit (1) and add coagulant into the coagulation tank unit (1). After mixing the kitchen waste wastewater or landfill leachate with the coagulant, send it into the flocculation tank unit (2). Step S2: Add flocculant to the flocculation tank, mix the coagulated liquid sent to the flocculation tank unit (2) in step S1 with the flocculant, and send the supernatant to the air flotation + filter unit (3) after sedimentation. Step S3: The supernatant is subjected to flotation and filtration in the flotation + filter unit (3), and the filtered clear liquid is sent to the ozone catalysis unit (4); Step S4: Ozone is introduced into the ozone catalytic unit (4), and the COD in the clear liquid entering the ozone catalytic unit (4) is removed by the catalysis of ozone. Step S5: The ozone-catalyzed solution from step S4 is sent to the activated carbon filter unit (7) for filtration, and the color of the solution is reduced.

2. The advanced oxidation coupled coagulation denitrification-based method for advanced treatment of organic wastewater according to claim 1, characterized in that, The coagulant is ferric chloride, and the flocculant is polyacrylamide. 3.The method and device for advanced treatment of organic wastewater based on the method of coupling coagulation and advanced oxidation process according to claim 1, characterized in that, In step S1, the leachate from the kitchen waste is mixed with the coagulant and left to stand for 3 to 8 minutes.

4. The advanced oxidation coupled coagulation denitrification based method for the advanced treatment of organic wastewater according to claim 1, characterized in that, In step S2, the coagulated liquid and flocculant in the flocculation tank unit (2) are mixed and then left to stand for 10 min to 20 min.

5. The advanced oxidation coupled coagulation denitrification based method for the advanced treatment of organic wastewater as claimed in claim 1, wherein, In step S3, the supernatant undergoes flotation and filtration in the flotation + filter unit (3) for 20 min to 40 min.

6. The treatment apparatus for advanced organic wastewater treatment based on the method of denitrification by coagulation coupled with advanced oxidation according to any one of claims 1 to 5, characterized in that, It includes a coagulation tank unit (1), a flocculation tank unit (2), an air flotation + filter unit (3), an ozone catalysis unit (4) and an activated carbon filter unit (7) connected in sequence, and also includes an ozone generation unit (5) and a tail gas decomposition unit (6) connected to the ozone catalysis unit (4).

7. The advanced organic wastewater treatment device based on advanced oxidation coupled coagulation denitrification as described in claim 6, characterized in that, Both the coagulation tank unit (1) and the flocculation tank unit (2) are equipped with a stirrer.

8. The advanced organic wastewater treatment device based on advanced oxidation coupled coagulation denitrification as described in claim 7, characterized in that, Both the coagulation tank unit (1) and the flocculation tank unit (2) contain multiple agitators.

9. The advanced organic wastewater treatment device based on advanced oxidation coupled coagulation denitrification as described in claim 6, characterized in that, The coagulation tank unit (1), flocculation tank unit (2), air flotation + filter unit (3), ozone catalysis unit (4) and activated carbon filter unit (7) all discharge liquid through overflow.

10. The advanced organic wastewater treatment device based on advanced oxidation coupled coagulation denitrification as described in claim 9, characterized in that, The coagulation tank unit (1), flocculation tank unit (2), air flotation + filter unit (3), ozone catalysis unit (4) and activated carbon filter unit (7) are connected in sequence and tightly, and the overflow port height connecting the coagulation tank unit (1), flocculation tank unit (2), air flotation + filter unit (3), ozone catalysis unit (4) and activated carbon filter unit (7) decreases by 5cm to 10cm in sequence.

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