Domestic sewage advanced treatment process

Abstract

The invention relates to the technical field of sewage treatment, and particularly discloses a domestic sewage advanced treatment process which comprises the following steps: mechanical grating impurity removal, balancing, integrated air floatation, anaerobic treatment, aerobic treatment, precipitation and biological adsorption. Wherein in the anaerobic treatment step, the hydraulic retention of an anaerobic tank is 8-10 hours; the microorganism concentration of anaerobic compound bacteria in the anaerobic tank is 3-6g / L; the anaerobic compound bacteria are a mixture of clostridium butyricum, bifidobacterium longum and methanogens; furthermore, the weight ratio of the clostridium butyricum to the bifidobacterium longum to the methanogens is 1: (0.4-0.6): (1.8-2.3). According to the domestic sewage advanced treatment process provided by the invention, refractory organic matters, suspended solids and ammonia nitrogen in domestic sewage can be effectively removed, so that the effluent quality is stable, and higher discharge and reuse standards can be reached.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and in particular to a deep treatment process for domestic sewage. Background Art

[0002] With the continuous acceleration of urbanization, the amount of domestic sewage discharged has shown a trend of increasing year by year. This not only puts tremendous pressure on the urban ecological environment but also poses a potential threat to people's quality of life. In this context, sewage treatment technology has become a key research direction in the field of environmental protection. Effective sewage treatment technology is of vital importance for protecting the environment and ensuring the sustainable use of water resources.

[0003] Currently, wastewater treatment technologies primarily fall into three categories: physical, chemical, and biological. Physical methods typically remove suspended solids from wastewater through sedimentation and filtration. Chemical methods primarily remove pollutants through the addition of reagents to initiate reactions such as coagulation and oxidation. Biological methods utilize the metabolic activity of microorganisms to degrade organic matter in wastewater. Microorganisms decompose and convert organic matter into nutrients, thereby purifying the wastewater. However, these traditional wastewater treatment technologies have limitations in practical application. When used alone, these technologies often suffer from low treatment efficiency and are unable to quickly and effectively remove pollutants from wastewater. Furthermore, some treatment methods may also generate secondary pollution, posing new environmental hazards. Summary of the Invention

[0004] In order to overcome the problems of limited treatment effect and easy secondary pollution when using existing sewage treatment methods alone, the present application provides a domestic sewage deep treatment process.

[0005] The domestic sewage deep treatment process provided in this application adopts the following technical solutions: A domestic sewage deep treatment process comprising the following steps: mechanical screen removal, equalization, integrated flotation, anaerobic treatment, aerobic treatment, sedimentation and biological adsorption; In the anaerobic treatment step, the hydraulic retention time in the anaerobic pool is 8-10 hours; the microbial concentration of the anaerobic composite bacteria in the anaerobic pool is 3-6 g / L; the anaerobic composite bacteria is a mixture of Clostridium butyricum, Bifidobacterium longum and methanogens.

[0006] The present application provides a process for deep treatment of domestic sewage, which first uses a mechanical screen to remove impurities, effectively intercepting large particles of impurities in the sewage, avoiding blockage of subsequent equipment, and ensuring the smooth operation of the entire treatment process; then, the water quality and water volume of the sewage are stabilized through the balancing step, creating good conditions for subsequent treatment. Subsequently, an integrated flotation process is used to effectively remove suspended matter, grease and other substances in the sewage, thereby improving the clarity of the sewage. Then, through anaerobic and aerobic treatment processes, the degradation and energy recovery of organic matter in the sewage are achieved under specific hydraulic retention time and microbial concentration; finally, through solid-liquid separation and biological adsorption, trace harmful substances and odors in the sewage can be further removed, so that the treated sewage meets more stringent emission standards. Compared with traditional sewage treatment processes, the deep treatment process for domestic sewage provided by the present application has higher treatment efficiency, lower energy consumption, and reduces the risk of secondary pollution, and has good application prospects.

[0007] In the present application, the anaerobic treatment step selects the type of anaerobic bacteria and controls the hydraulic retention time of the anaerobic tank and the microbial concentration of the anaerobic tank within the above-mentioned specific range. Through the synergistic effect of the strains, the advantages of each strain can be effectively exerted, the organic matter content in the wastewater can be greatly reduced, and efficient degradation of organic matter and energy recovery can be achieved; among them, Clostridium butyricum mainly participates in the hydrolysis and acidification process of organic matter, decomposing complex macromolecular organic matter (proteins, polysaccharides and fats, etc.) in sewage into simple small molecular organic matter, such as fatty acids and alcohols; Bifidobacterium longum can assist Clostridium butyricum in participating in the decomposition of macromolecular organic matter, making the degradation of macromolecular organic matter more sufficient and thorough; methanogens mainly play a role in the final stage of anaerobic treatment of sewage, using the organic matter produced by hydrolysis and acidification as a matrix to convert volatile fatty acids and the like into harmless methane and carbon dioxide, thereby achieving efficient degradation of organic matter and energy recovery.

[0008] Optionally, the weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens is 1:(0.4-0.6):(1.8-2.3).

[0009] In some embodiments, the weight ratio of Clostridium butyricum, Bifidobacterium longum, and methanogens may be 1:(0.4-0.5):2, 1:(0.5-0.6):2, 1:0.5:(1.8-2), or 1:0.5:(2-2.3).

[0010] In a specific embodiment, the weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens can also be 1:0.4:2, 1:0.5:2, 1:0.6:2, 1:0.5:1.8, 1:0.5:2, 1:0.2:2 or 1:1:2.

[0011] Optionally, the weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens is 1:0.5:2.

[0012] Optionally, the microbial concentration of anaerobic composite bacteria in the anaerobic tank is 4-5 g / L.

[0013] In some embodiments, the microbial concentration of the anaerobic complex bacteria in the anaerobic tank may be 3-4 g / L, 3-5 g / L, 4-5 g / L, 4-6 g / L, or 5-6 g / L.

[0014] In a specific embodiment, the microbial concentration of the anaerobic composite bacteria in the anaerobic tank can be 3 g / L, 4 g / L, 5 g / L or 6 g / L.

[0015] Optionally, the aerobic pool has a hydraulic retention time of 12-15 hours, and a dissolved oxygen concentration DO=2-4 mg / L; and the main components of aerobic bacteria in the aerobic pool are Bacillus and Pseudomonas.

[0016] Optionally, in the equalization step, the pH is 6.5-8.5, the temperature is 15-30° C., and the equalization time is 6-8 h.

[0017] Optionally, in the precipitation step, the precipitated sludge is returned to the anaerobic tank; the supernatant enters the ozone generator and is oxidized by ozone to break the chain of refractory organic matter.

[0018] Optionally, in the biological adsorption step, coal-based activated carbon with a specification of 2.5 mm is used for adsorption.

[0019] In summary, this application has the following beneficial effects: 1. This application uses Clostridium butyricum, Bifidobacterium longum and methanogens as anaerobic composite bacteria in anaerobic treatment, and controls the hydraulic retention of the anaerobic tank within the range of 8-10h, and the microbial concentration of the anaerobic composite bacteria within the range of 3-6g / L, which can achieve a removal rate of organic matter in domestic sewage of more than 90%. In addition, the domestic sewage deep treatment process provided by this application can also remove solid suspended matter SS and ammonia nitrogen in the sewage, so that the effluent meets the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (DB11 / 890-2012) A standard.

[0020] 2. This application further controls the weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens in the anaerobic composite bacteria within the range of 1: (0.4-0.6): (1.8-2.3). Its anaerobic process removes organic matter in domestic sewage more thoroughly, and the organic matter content in the effluent is lower. DETAILED DESCRIPTION

[0021] The present application provides a domestic sewage deep treatment process, comprising the following steps: (1) Domestic sewage enters the screen well and is mechanically screened to remove debris with a size of ≥5 mm; (2) The water enters the regulating tank to adjust the pH to 6.5-8.5 and the temperature to 15-30℃, and then balance for 6-8 hours to ensure the stability of the water volume in the subsequent process; (3) Entering the integrated flotation equipment, the oil content in the wastewater is reduced through the flotation process to meet the requirements of the subsequent membrane process for the oil content of the influent, while also removing some SS and TP; (4) Enter the anaerobic tank for hydrolysis and acidification, and then enter the aerobic tank to complete carbonization and nitrification; The anaerobic tank has a hydraulic retention period of 8-10 hours and an oxidation-reduction potential (ORP) of ≤-200 mV; the microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 3-6 g / L; the anaerobic composite bacteria are Clostridium butyricum, Bifidobacterium longum, and methanogens in a weight ratio of 1:(0.4-0.6):(1.8-2.3); The aerobic pool has a hydraulic retention period of 12-15 hours and a dissolved oxygen concentration (DO) of 2-4 mg / L; the main components of aerobic bacteria in the aerobic pool are Bacillus and Pseudomonas; (5) The sludge enters the sedimentation tank for sedimentation, and then flows back to the anaerobic tank; the supernatant enters the ozone generator, where it is oxidized by ozone to break the chain of refractory organic matter; (6) Enter the biological activated carbon filter, which is filled with coal-based activated carbon with a specification of 2.5mm. The filter is filtered at a filtration rate of 3-5m / h to remove residual pollutants, and then discharged or reused after disinfection and meeting the standards.

[0022] In the examples of the present application, the viable count of Clostridium butyricum is 10 billion cfu / g, purchased from Wuhan Jiyesheng Chemical Co., Ltd.; the viable count of Bifidobacterium longum is 10 billion cfu / g, purchased from Hebei Hongtao Bioengineering Co., Ltd.; the viable count of methanogens is ≥ 200 million cfu / g, model QWWS-06, purchased from Guangzhou Anjianhuan Engineering Consulting Co., Ltd.; the aerobic bacteria model is JY-015, purchased from Yixing Jiashengda Environmental Protection Technology Co., Ltd. The raw materials, reagents, solvents, etc. used in this application can all be obtained commercially.

[0023] The present application is further described in detail below with reference to preparation examples, embodiments and performance testing experiments.

[0024] Preparation Examples 1-7 Preparation Examples 1-7 each provide an anaerobic composite bacteria.

[0025] The difference between the above preparation examples is that the weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens is shown in Table 1 below.

[0026] The preparation method of the anaerobic composite bacteria provided in Preparation Example 1-7 is as follows: Clostridium butyricum, Bifidobacterium longum and methanogens are uniformly mixed in a specific weight ratio to obtain the anaerobic composite bacteria.

[0027] Table 1 The ratio of each anaerobic bacteria in the anaerobic composite bacteria provided in Preparation Examples 1-7 Comparative Preparation Example 1 Comparative Preparation Example 1 provides an anaerobic composite bacteria.

[0028] The difference between the comparative preparation example and preparation example 2 is that the anaerobic composite bacteria are Clostridium butyricum and methanogens in a weight ratio of 1.5:2.

[0029] Comparative Preparation Example 2 Comparative Preparation Example 2 provides an anaerobic composite bacteria.

[0030] The difference between the comparative preparation example and preparation example 2 is that the anaerobic composite bacteria are Bifidobacterium longum and methanogens in a weight ratio of 1.5:2.

[0031] Comparative Preparation Example 3 Comparative Preparation Example 3 provides an anaerobic composite bacteria.

[0032] The difference between the comparative preparation example and preparation example 2 is that the anaerobic composite bacteria are Bacillus subtilis, Bifidobacterium longum and methanogens in a weight ratio of 1:0.5:2.

[0033] Comparative Preparation Example 4 Comparative Preparation Example 4 provides an anaerobic composite bacteria.

[0034] The difference between the comparative preparation example and preparation example 2 is that the anaerobic composite bacteria are Clostridium butyricum, Bacillus subtilis and methanogens in a weight ratio of 1:0.5:2.

[0035] Examples 1-7 Examples 1-7 each provide a process for deep treatment of domestic sewage.

[0036] The difference between the above embodiments is that the anaerobic composite bacteria used in the anaerobic treatment step are derived from Preparation Examples 1-7 respectively.

[0037] The domestic sewage advanced treatment process provided in Examples 1-7 comprises the following steps: (1) Domestic sewage enters the screen well and is mechanically screened to remove debris with a size of ≥5 mm; (2) The water enters the regulating tank to adjust the pH to 6.5-8.5 and the temperature to 15-30℃, and then balance for 6-8 hours to ensure the stability of the water volume in the subsequent process; (3) Entering the integrated flotation equipment, the oil content in the wastewater is reduced through the flotation process to meet the requirements of the subsequent membrane process for the oil content of the influent, while also removing some SS and TP; (4) Enter the anaerobic tank for hydrolysis and acidification, and then enter the aerobic tank to complete carbonization and nitrification; The anaerobic tank is hydraulically retained for 10 hours, and the redox potential (ORP) is controlled within the range of -200 to -250 mV; the microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 5 g / L; The aerobic pool is hydraulically retained for 12 hours, and the dissolved oxygen concentration (DO) is controlled at 3 mg / L; the main components of aerobic bacteria in the aerobic pool are Bacillus and Pseudomonas; (5) The sludge enters the sedimentation tank for sedimentation, and then flows back to the anaerobic tank; the supernatant enters the ozone generator, where it is oxidized by ozone to break the chain of refractory organic matter; (6) Enter the biological activated carbon filter, which is filled with coal-based activated carbon with a specification of 2.5mm. The filter is filtered at a filtration rate of 4m / h to remove residual pollutants, and then discharged or reused after disinfection and meeting the standards.

[0038] Example 8 Example 8 provides a domestic sewage deep treatment process.

[0039] The difference between the above embodiment and embodiment 2 is that the microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 3 g / L.

[0040] Example 9 Example 9 provides a process for deep treatment of domestic sewage.

[0041] The difference between the above embodiment and embodiment 2 is that the microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 4 g / L.

[0042] Example 10 Example 10 provides a domestic sewage deep treatment process.

[0043] The difference between the above embodiment and embodiment 2 is that the microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 6 g / L.

[0044] Example 11 Example 11 provides a domestic sewage deep treatment process.

[0045] The difference between the above embodiment and embodiment 2 is that the hydraulic retention time in the anaerobic tank is 8 hours.

[0046] Comparative Examples 1-4 Comparative Examples 1-4 respectively provide a domestic sewage deep treatment process.

[0047] The difference between the comparative example and Example 2 is that the anaerobic composite bacteria used in the anaerobic treatment step are derived from comparative preparation examples 1-4, respectively.

[0048] Comparative Example 5 Comparative Example 5 provides a domestic sewage deep treatment process.

[0049] The difference between the comparative example and Example 2 is that the microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 2 g / L.

[0050] Comparative Example 6 Comparative Example 6 provides a domestic sewage deep treatment process.

[0051] The difference between the comparative example and Example 2 is that the hydraulic retention time in the anaerobic tank is 6 hours.

[0052] Performance testing The same batch of domestic sewage was treated using the deep treatment processes for domestic sewage provided in Examples 1-11 and Comparative Examples 1-6, and the COD, SS, and NH3-N contents of the influent and effluent were tested, respectively. The results are shown in Table 2 below.

[0053] The test method for chemical oxygen demand (COD) content is GB / T 11914-1989; the test method for suspended solids (SS) content is GB / T 11914-1989; the test method for ammonia nitrogen (NH3-N) content is HJ 535-2009; Note: The inlet water quality of domestic sewage is: chemical oxygen demand COD content is about 437.7 mg / L, suspended solids SS content is about 219~236 mg / L, ammonia nitrogen NH3-N content is about 36~38 mg / L.

[0054] In the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" (DB11 / 890-2012) A standard, the emission limits for water pollutants in urban wastewater treatment plants are: chemical oxygen demand (CDO) 6-9 mg / L, suspended solids (SS) 5 mg / L, ammonia nitrogen (NH3-N) 1.0 (1.5) Table 2 Test results of various indicators of effluent water quality obtained by the treatment processes of Examples 1-11 and Comparative Examples 1-6 According to the test results in Table 2, after treating the same batch of domestic sewage using the advanced domestic sewage treatment process provided in Examples 1-11, the effluent COD content was 3.78-8.74 mg / L, the SS content was 3.7-4.9 mg / L, and the NH3-N content was 0.2-0.8 mg / L. After treating the same batch of domestic sewage using the advanced domestic sewage treatment process provided in Comparative Examples 1-6, the effluent COD content was as high as 65.5-91.46 mg / L, the SS content was 4.1-4.9 mg / L, and the NH3-N content was 0.4-0.8 mg / L. Therefore, it is explained that the present application adopts Clostridium butyricum, Bifidobacterium longum and methanogens as anaerobic composite bacteria in anaerobic treatment, and controls the hydraulic retention of the anaerobic tank within the range of 8-10h, and the microbial concentration of the anaerobic composite bacteria within the range of 3-6g / L, which can make the removal rate of organic matter in domestic sewage reach more than 90%, and the domestic sewage deep treatment process provided by the present application can also remove solid suspended matter SS and ammonia nitrogen in the sewage, and the effluent can meet the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (DB11 / 890-2012) A standard.

[0055] Further comparison of the test results of Examples 1-7 revealed that after the same batch of domestic sewage was treated using the domestic sewage deep treatment process provided in Example 1-5, the COD content of the effluent was only 3.78-6.14 mg / L (≤7.00 mg / L); after the same batch of domestic sewage was treated using the domestic sewage deep treatment process provided in Examples 6-7, the COD content of the effluent was 8.22-8.74 mg / L. This indicates that the present application further controls the weight ratio of Clostridium butyricum, Bifidobacterium longum, and methanogens in the anaerobic composite bacteria within the range of 1:(0.4-0.6):(1.8-2.3), resulting in a more thorough removal of organic matter from domestic sewage and a lower organic matter content in the effluent.

[0056] Further comparison of the test results of Example 2 and Examples 8-10 revealed that after the same batch of domestic sewage was treated using the domestic sewage deep treatment process provided in Example 2 and Example 9, the COD content of the effluent was only 3.78-4.24 mg / L (≤25 mg / L); after the same batch of domestic sewage was treated using the domestic sewage deep treatment process provided in Example 8 and Example 10, the COD content of the effluent was 6.14-7.72 mg / L. This indicates that the present application further controls the microbial concentration of anaerobic composite bacteria in the anaerobic tank within the range of 4-5 g / L, resulting in more thorough removal of organic matter from domestic sewage and a lower organic matter content in the effluent.

[0057] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A domestic sewage deep treatment process, characterized in that: The following steps are involved: Mechanical screen removal, balancing, integrated flotation, anaerobic treatment, aerobic treatment, sedimentation and biosorption; In the anaerobic treatment step, the hydraulic retention time in the anaerobic pool is 8-10 hours; the microbial concentration of the anaerobic composite bacteria in the anaerobic pool is 3-6 g / L; the anaerobic composite bacteria is a mixture of Clostridium butyricum, Bifidobacterium longum and methanogens.

2. The domestic sewage deep treatment process according to claim 1, characterized in that: The weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens is 1: (0.4-0.6): (1.8-2.3).

3. The domestic sewage deep treatment process according to claim 1, characterized in that: The weight ratio of Clostridium butyricum, Bifidobacterium longum and methanogens is 1:0.5:

2.

4. The domestic sewage deep treatment process according to claim 1, characterized in that: The microbial concentration of the anaerobic composite bacteria in the anaerobic tank is 4-5 g / L.

5. The domestic sewage deep treatment process according to claim 1, characterized in that: The aerobic pool has a hydraulic retention period of 12-15 hours and a dissolved oxygen concentration DO of 2-4 mg / L; the main components of aerobic bacteria in the aerobic pool are Bacillus and Pseudomonas.

6. The domestic sewage deep treatment process according to claim 1, characterized in that: In the equalization step, the pH is 6.5-8.5, the temperature is 15-30° C., and the equalization time is 6-8 hours.

7. The domestic sewage deep treatment process according to claim 1, characterized in that: In the precipitation step, the precipitated sludge is returned to the anaerobic tank; the supernatant enters the ozone generator and is oxidized by ozone to break the chain of the refractory organic matter.

8. The domestic sewage advanced treatment process according to claim 1, characterized in that: In the biological adsorption step, coal-based activated carbon with a specification of 2.5 mm is used for adsorption.

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