Advanced treatment method for Shuanghuanglian production wastewater for upgrading and reconstruction

Abstract

The invention relates to an advanced treatment method for Shuanghuanglian production wastewater for upgrading and reconstruction, which can effectively solve the problem that secondary effluent of an existing wastewater treatment process of a Shuanghuanglian production or pharmaceutical enterprise cannot meet the current sewage treatment comprehensive discharge standard. Comprising the following steps: 1) introducing effluent of a secondary sedimentation tank or an aerobic tank of an original process into an MBR membrane tank; 2) enabling effluent of the MBR membrane tank to enter a micro-nano bubble-ozone catalytic oxidation tower; 3) passing through a buffer pool and then entering a BAF (Biological Aerated Filter); and 4) finally passing through a fiber rotating disc filter tank to achieve the purpose of up-to-standard discharge. Micro-nano bubble-ozone catalytic oxidation is adopted to overcome the defects of weak oxidation capacity, low reaction rate, poor selectivity and the like of the traditional ozone oxidation technology in wastewater treatment, and the biotoxicity in wastewater treatment is effectively eliminated; the biodegradability and the effluent standard of the wastewater are improved, and the advanced treatment method for the Shuanghuanglian production wastewater is an innovation.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to a method for deep treatment of Shuanghuanglian production wastewater for upgrading and transformation. Background Art

[0002] Shuanghuanglian production enterprises mainly use Scutellaria baicalensis for Chinese medicine extraction. The Chinese medicine wastewater generated mainly includes production wastewater and a small amount of domestic and office wastewater. The production wastewater mainly includes medicine washing and soaking wastewater in the pre-treatment workshop, decoction wastewater and some extracts and flushing discharge wastewater in the Scutellaria baicalensis extraction workshop. The water quality characteristics of the wastewater are acidic wastewater with a pH of about 1.0-2.0. The wastewater mainly contains residues of effective ingredients of Chinese medicine, lignin, cellulose, hemicellulose, aged macroporous resins, organic solvents (ethanol), glycosides, anthraquinones, alkaloids and their hydrolysis products, etc. It has complex components, high organic concentration, high suspended matter, and high sulfide. In addition, the water volume fluctuates greatly over time. Moreover, the concentration of pollutants in sewage is relatively high, COD is generally above 30,000 mg / L, and BOD5 is relatively low, generally below 10,000 mg / L.

[0003] At present, the main treatment processes such as "coagulation and sedimentation + ABR (anaerobic baffle reactor) + UBF (upflow sludge bed filter) + aerated sedimentation + A / O" are usually used to treat this type of wastewater, and the COD of the effluent from the secondary sedimentation tank is about 100-120 mg / L. With the improvement of comprehensive sewage treatment discharge standards in various places, the effluent standard has been raised to level one or reached the Yellow River Basin discharge standard. The sewage stations of related companies are facing upgrades and renovations to meet the standard emissions stipulated by local governments. On the basis of optimizing the existing process, it is also necessary to add deep treatment processes at the back end. There is an urgent need for a process technology that can further degrade difficult-to-degrade pollutants, has low investment costs, and is easy to maintain and manage, so as to achieve effluent discharge standards. Therefore, it is imperative to invent a method for deep wastewater treatment. Summary of the invention

[0004] In view of the above situation, in order to solve the defects of the prior art, the purpose of the present invention is to provide a method for deep treatment of Shuanghuanglian production wastewater, which can effectively solve the problem that the secondary effluent of the existing wastewater treatment process of Shuanghuanglian production or pharmaceutical enterprises cannot meet the current comprehensive sewage treatment discharge standards.

[0005] The technical solution provided by the present invention is that the method for deep treatment of Shuanghuanglian production wastewater for upgrading and transformation comprises the following steps: 1) First, the effluent from the secondary sedimentation tank or aerobic tank of the original process is passed into the MBR membrane tank. Due to the high efficiency of the membrane, a high concentration of microorganisms can be maintained to degrade undegraded organic matter as much as possible; 2) The effluent from the MBR membrane pool enters the micro-nano bubble-ozone catalytic oxidation tower. Under the action of the catalyst, ozone oxidizes and decomposes the difficult-to-degrade high-molecular organic matter in the wastewater into easily degradable small-molecular organic matter; 3) After passing through the buffer tank, it enters the BAF aerated biological filter tank, where the aerobic bacteria and nitrifying bacteria on the biofilm achieve the purpose of carbon removal and nitrogen removal; 4) Finally, it passes through the fiber disc filter to intercept SS, making the effluent COD, NH3-N and SS concentrations relatively low, achieving the purpose of meeting emission standards.

[0006] In the step 1), the hydraulic retention time of the MBR membrane pool is controlled at 3.5h, the dissolved oxygen is 2-4mg / L, the sludge concentration is maintained at 10000-12000mg / L, and the COD of the MBR effluent is 70-90mg / L; In the step 2), the micro-nano bubble-ozone catalytic oxidation tower controls the ozone concentration to 40-55%, the bubble particle size is less than 250nm, the reaction time is 60-180min, and the COD removal rate can reach 60%.

[0007] In the step 2), the micro-nano bubble-ozone catalytic oxidation tower catalyst is a composite precious metal γ-Al2O3-based catalyst, containing one or more of Mn, Co, Ni, and Ce, and the catalyst filling amount (volume) accounts for 1 / 5-1 / 3 of the oxidation tower.

[0008] In the step 3), the dissolved oxygen in the BAF aerated biological filter is controlled at 1-2 mg / L.

[0009] In the step 4), the filtration accuracy of the fiber rotary disc filter is 10-20 μm.

[0010] The present invention adopts micro-nano bubble-ozone catalytic oxidation to overcome the defects of traditional ozone oxidation technology in wastewater treatment, such as weak oxidation ability, low reaction rate and poor selectivity, effectively eliminates biological toxicity in wastewater treatment, improves the biodegradability and effluent standards of wastewater, and is an innovation in the deep treatment method of Shuanghuanglian production wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a process flow chart of the present invention.

[0012] Figure 2 It is a structural connection frame diagram of the micro-nano bubble-ozone catalytic oxidation tower of the present invention. DETAILED DESCRIPTION

[0013] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. Example

[0014] In the specific implementation of the present invention, a wastewater deep treatment device is used, and then the following steps are performed: 1) The effluent from the secondary sedimentation tank or aerobic tank of the original process is passed into the MBR membrane tank, and the sludge concentration of the membrane tank is controlled at 10000-12000 mg / L, the hydraulic retention time is controlled at 3.5h, the dissolved oxygen is controlled at 2-4 mg / L, and the effluent COD is 70-90 mg / L; 2) The effluent from the MBR membrane pool is pumped into the micro-nano bubble-ozone catalytic oxidation tower, which is filled with a composite precious metal γ-Al2O3-based catalyst, including one or more of Mn, Co, Ni, and Ce, and the catalyst filling volume (volume) accounts for 1 / 5-1 / 3 of the oxidation tower. The reaction conditions are controlled to be an ozone concentration of 40-55%, a bubble particle size of less than 250nm, and a reaction time of 60-180min. Pollutants that cannot be biodegraded at the front end are mineralized and decomposed in the micro-nano bubble-ozone catalytic oxidation tower through a comprehensive effect of adsorption, coordination complexation, and hydroxyl radical chain reaction, and the COD removal rate can reach 60%; 3) The effluent from the ozone catalytic oxidation tower enters the buffer tank. The function of the buffer tank is to make the ozone in the effluent from the ozone catalytic oxidation tower further react and decompose to avoid harm to the microorganisms in the subsequent internal circulation BAF. After passing through the buffer tank, it enters the BAF aerated biological filter. The dissolved oxygen is controlled at 1-2 mg / L. The carbonized organic matter in the wastewater is aerobic biodegraded, and TKN (Kjeldahl nitrogen) is partially converted into nitrate nitrogen. The effluent COD, NH3-N, TN, and TP can all stably meet the standards. 4) The effluent from the BAF aerated biological filter enters a fiber disc filter with a filtration accuracy of 10-20μm to intercept SS, making the effluent COD, NH3-N and SS concentrations relatively low. Since the microorganisms in the BAF may cause SS to exceed the standard, it needs to be removed by a filtration device. Therefore, the selection of a fiber disc filter is a guaranteed process for removing SS, ensuring that the effluent SS, COD, NH3-N and other indicators can meet the emission standards.

[0015] In order to ensure the use effect, the wastewater deep treatment device includes an MBR membrane pool, a micro-nano bubble-ozone catalytic oxidation tower, a buffer tank, a BAF aerated biological filter and a fiber rotary filter. The water outlet of the MBR membrane pool is connected to the water inlet of the micro-nano bubble-ozone catalytic oxidation tower through a pipeline, the water outlet of the micro-nano bubble-ozone catalytic oxidation tower is connected to the water inlet of the buffer tank through a pipeline, the water outlet of the buffer tank is connected to the water inlet of the BAF aerated biological filter through a pipeline, and the water outlet of the BAF aerated biological filter is connected to the water inlet of the fiber rotary filter through a pipeline.

[0016] The MBR membrane pool membrane component is in the form of a hollow fiber membrane or a flat membrane.

[0017] The micro-nano bubble-ozone catalytic oxidation tower is composed of a cylindrical tower body, an ozone generator, and a micro-nano bubble generator. The ozone outlet of the ozone generator is connected to the air inlet of the micro-nano bubble generator through a pipeline. The micro-nano bubble generator is connected to an ozone delivery pipeline arranged at the bottom of the tower body. A flow control valve is provided on the ozone delivery pipeline. The tower body is filled with a catalyst. A water inlet pipeline is provided on the upper part of the tower body, and a water outlet pipeline is provided at the bottom. The water inlet pipeline is connected to a nozzle in the tower body. The nozzle can spray sewage in the tower in the form of a spray, thereby increasing the contact area between the sewage and the ozone micro-nano bubbles.

[0018] The present invention is used in that the wastewater produced by Shuanghuanglian contains lignocellulose, which is a high molecular organic matter that is difficult to degrade. It also contains polysaccharides, flavonoids and other substances that have biological inhibition. It is difficult to reach the first-level standard for comprehensive wastewater discharge by using general physical and biochemical treatment. The micro-nano bubble-ozone catalytic oxidation modified by the present invention is that ozone is adsorbed on the catalytic active center of the catalyst and decomposed to produce hydroxyl radicals (•OH) and superoxide anion radicals (•O2 − ) and other active substances, thereby inducing a free radical chain reaction on the catalyst surface and in the solution to decompose organic matter. The introduction of micro-nano bubbles accelerates the progress of the reaction because, compared with ordinary microporous aeration, it can improve the mass transfer efficiency of ozone, reduce the ineffective decomposition of ozone, increase the ozone concentration, and further enhance the efficiency of ozone catalytic oxidation. The MBR and BAF combined process of the present invention is an extension of the traditional process for achieving standard emissions. The effluent from the secondary sedimentation tank passes through the MBR, which can not only intercept suspended matter, but also maintain a high sludge concentration in the membrane tank, degrading undegraded organic matter as much as possible. Before entering the micro-nano bubble-ozone catalytic oxidation, the COD is reduced to 70-90 mg / L; micro-nano bubble-ozone catalysis has the characteristics of strong oxidation ability, small footprint, and no secondary pollution. It can directly degrade or convert the undegraded macromolecular organic matter in the biochemical part into easily degradable small molecular organic matter, and then remove the pollution factors through biological (BAF) and filtration treatment to ensure that the effluent COD is stable at 30-40 mg / L, and it has been proved by field practice: Example 1: The peak amount of production wastewater generated by a Shuanghuanglian production enterprise is 120m³ / day. The main production raw material is Astragalus. The existing wastewater treatment process adopts "coagulation sedimentation + ABR (anaerobic baffled reactor) + UBF (upflow sludge bed filter) + A / O + filtration + secondary sedimentation tank". The current effluent indicators are COD: 133.9mg / L, NH3-N: 20.76mg / L, TN: 50.89mg / L, TP: 0.85mg / L.

[0019] The effluent from the secondary sedimentation tank enters the MBR pool. The sludge retention time of the MBR membrane pool is controlled at 3.5h, the dissolved oxygen is 4mg / L, the sludge concentration is maintained at 10000mg / L, and the COD of the MBR effluent is 85mg / L; the effluent from the MBR pool is pumped into the micro-nano bubble-ozone catalytic oxidation tower, which is equipped with a precious metal ozone catalyst. The filler volume accounts for 1 / 5 of the tower and is filled in two layers. At the same time, the ozone concentration is controlled at 50%, the reaction time is 120min, and the effluent COD is 45mg / L. The effluent from the oxidation tower enters the intermediate buffer tank, and the ozone in the water further oxidizes and decomposes organic matter to avoid harm to the microorganisms in the subsequent internal circulation BAF. The buffer tank water is pumped into the BAF aerated biological filter, the dissolved oxygen is controlled at 2mg / L, and the effluent COD is 37mg / L. The effluent from the BAF enters the 10μm fiber rotary filter, and the suspended solids are removed before being discharged in compliance with the standards.

[0020] Comparative Example 1 (the difference from Example 1 is that no noble metal ozone catalyst is added): The effluent from the secondary sedimentation tank enters the MBR pool. The sludge retention time of the MBR membrane pool is controlled at 3.5h, the dissolved oxygen is 4mg / L, the sludge concentration is maintained at 10000mg / L, and the COD of the MBR effluent is 85mg / L; the effluent from the MBR pool is pumped into the micro-nano bubble-ozone catalytic oxidation tower. The tower is an empty tower. The ozone concentration is also controlled at 50%, the reaction time is 120min, and the effluent COD is 68mg / L. The effluent from the oxidation tower enters the intermediate buffer tank. The ozone in the water further oxidizes and decomposes organic matter to avoid harm to the microorganisms in the subsequent internal circulation BAF. The buffer tank water is pumped into the BAF aerated biological filter, the dissolved oxygen is controlled at 2mg / L, and the effluent COD is 61mg / L. The effluent from the BAF enters the 10μm fiber rotary filter, and it still does not meet the standard after removing suspended solids.

[0021] Comparative Example 2 (the difference from Example 1 is that no noble metal ozone catalyst is added and the ozone oxidation time is extended to 4 hours): The effluent from the secondary sedimentation tank enters the MBR pool. The sludge retention time of the MBR membrane pool is controlled at 3.5h, the dissolved oxygen is 4mg / L, the sludge concentration is maintained at 10000mg / L, and the COD of the MBR effluent is 85mg / L; the effluent from the MBR pool is pumped into the micro-nano bubble-ozone catalytic oxidation tower. The tower is an empty tower, and the ozone concentration is also controlled at 50%, the reaction time is 240min, and the effluent COD is 90.3mg / L. The effluent from the oxidation tower enters the intermediate buffer tank, and the ozone in the water further oxidizes and decomposes the organic matter to avoid harm to the microorganisms in the subsequent internal circulation BAF. The buffer tank water is pumped into the BAF aerated biological filter, the dissolved oxygen is controlled at 2mg / L, and the effluent COD is 80mg / L. The effluent from the BAF enters the 10μm fiber rotary filter, and it still does not meet the standard after removing the suspended solids.

[0022] The above experiments verified the single factor effects of catalyst and catalytic oxidation reaction time on the micro-nano bubble-ozone catalytic treatment of the effluent from the secondary sedimentation tank of Shuanghuanglian production wastewater, and obtained the optimal solution of the present invention in treating this type of wastewater. The micro-nano bubble-ozone catalytic oxidation, MBR, and BAF combined process proposed in the present invention adapts to the new standards and new requirements of the environmental protection industry, and is suitable for promotion and application in the deep treatment of wastewater in pharmaceutical enterprises. It is an innovation in the deep treatment method of Shuanghuanglian production wastewater, and has good economic and social benefits.

[0023] It should be pointed out that the above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession can make changes or modify the technical contents disclosed above into equivalent embodiments with equivalent changes without departing from the scope of the technical solution of the present invention, which all fall within the protection scope of the present invention.

Claims

1. A method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater, characterized in that: Use the wastewater deep treatment device and then proceed as follows: 1) First, the effluent from the secondary sedimentation tank or aerobic tank of the original process is passed into the MBR membrane tank. Due to the high efficiency of the membrane, a high concentration of microorganisms can be maintained to degrade undegraded organic matter as much as possible; 2) The effluent from the MBR membrane pool enters the micro-nano bubble-ozone catalytic oxidation tower. Under the action of the catalyst, ozone oxidizes and decomposes the difficult-to-degrade high-molecular organic matter in the wastewater into easily degradable small-molecular organic matter; 3) After passing through the buffer tank, it enters the BAF aerated biological filter tank, where the aerobic bacteria and nitrifying bacteria on the biofilm achieve the purpose of carbon removal and nitrogen removal; 4) Finally, it passes through the fiber disc filter to intercept SS, making the effluent COD, NH3-N and SS concentrations relatively low, achieving the purpose of meeting emission standards.

2. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater according to claim 1, characterized in that: In the step 1), the hydraulic retention time of the MBR membrane pool is controlled at 3.5h, the dissolved oxygen is 2-4mg / L, the sludge concentration is maintained at 10000-12000mg / L, and the COD of the MBR effluent is 70-90mg / L.

3. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the product according to claim 1, characterized in that: In the step 2), the micro-nano bubble-ozone catalytic oxidation tower controls the ozone concentration to 40-55%, the bubble particle size is less than 250nm, the reaction time is 60-180min, and the COD removal rate can reach 60%; the catalyst of the micro-nano bubble-ozone catalytic oxidation tower is a composite precious metal γ-Al2O3-based catalyst, containing one or more of Mn, Co, Ni, and Ce, and the catalyst filling amount accounts for 1 / 5-1 / 3 of the oxidation tower.

4. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater according to claim 1, characterized in that: In step 3) described above, the dissolved oxygen in the BAF aerated biological filter is controlled at 1-2 mg / L.

5. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater according to claim 1, characterized in that: In the step 4), the filtration accuracy of the fiber rotary disc filter is 10-20 μm.

6. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater according to claim 1, characterized in that: The wastewater deep treatment device comprises an MBR membrane pool, a micro-nano bubble-ozone catalytic oxidation tower, a buffer tank, a BAF aerated biological filter and a fiber rotary filter. The water outlet of the MBR membrane pool is connected to the water inlet of the micro-nano bubble-ozone catalytic oxidation tower via a pipeline, the water outlet of the micro-nano bubble-ozone catalytic oxidation tower is connected to the water inlet of the buffer tank via a pipeline, the water outlet of the buffer tank is connected to the water inlet of the BAF aerated biological filter via a pipeline, and the water outlet of the BAF aerated biological filter is connected to the water inlet of the fiber rotary filter via a pipeline.

7. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater according to claim 6, characterized in that: The MBR membrane pool membrane component is in the form of a hollow fiber membrane or a flat membrane.

8. The method for deep treatment of Shuanghuanglian production wastewater for upgrading the quality of the wastewater according to claim 6, characterized in that: The micro-nano bubble-ozone catalytic oxidation tower is composed of a cylindrical tower body, an ozone generator, and a micro-nano bubble generator. The ozone outlet of the ozone generator is connected to the air inlet of the micro-nano bubble generator through a pipeline. The micro-nano bubble generator is connected to an ozone delivery pipeline arranged at the bottom of the tower body. A flow control valve is provided on the ozone delivery pipeline. The tower body is filled with a catalyst. A water inlet pipeline is provided on the upper part of the tower body, and a water outlet pipeline is provided at the bottom. The water inlet pipeline is connected to a nozzle in the tower body. The nozzle can spray sewage in the tower in the form of a spray, thereby increasing the contact area between the sewage and the ozone micro-nano bubbles.

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