A septic tank sewage treatment device and its application

Abstract

The present invention discloses a septic tank sewage treatment device and its application, belonging to the field of environmental protection technology. The treatment device includes an inlet area, a sewage treatment unit and an outlet area. The sewage treatment unit includes a supporting layer, a mixed filler layer and a surface layer from bottom to top. Wetland plants are planted above the sewage treatment unit; the filler of the supporting layer is rock, the filler of the mixed filler layer is pyrolusite and pyrite, and the filler of the surface layer is biochar. The present invention adopts a bottom-in and top-out water inlet method to maintain the anaerobic environment of the treatment device, which can achieve efficient removal of organic matter, ammonia nitrogen, phosphate and soluble methane in the effluent of the septic tank, further alleviate the blockage of the treatment device and prevent the generation of endogenous methane, while preventing the leakage of heavy metals to cause secondary pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and specifically relates to a septic tank sewage treatment device and application thereof. Background Art

[0002] For a long time, decentralized sewage treatment in rural areas has been a daunting challenge. Septic tanks are currently the most common sewage purification devices, but the high concentration of ammonia nitrogen and saturated dissolved methane in septic tank sewage has brought more challenging problems. Constructed wetlands are widely used in decentralized sewage treatment in rural areas due to their low construction and operation costs, good water purification effects, and strong resistance to shock loads. However, their limited reoxygenation capacity and low oxygen environment limit their ability to oxidize ammonia nitrogen and methane.

[0003] At present, there is a vertical flow artificial wetland system for greenhouse gas emission reduction, which can utilize tidal flow manganese ore artificial wetlands to enhance the anaerobic oxidation of methane. However, the changes in oxygen concentration caused by the tidal flow operation mode will affect the activity of anaerobic methane oxidizing bacteria, thereby affecting the anaerobic oxidation of methane. There is also a manganese ore artificial wetland coupled microbial fuel cell system in the prior art, which introduces the anaerobic oxidation process of methane driven by the microbial fuel cell system and natural manganese ore, reducing the generation and transmission of methane. However, this technical solution has limited oxidation capacity for ammonia nitrogen, and the anaerobic oxidation pathway for methane is single, and thus the oxidation capacity is limited.

[0004] The above technical solutions are more suitable for endogenous methane reduction in artificial wetlands, but lack research on exogenous methane removal. In addition, all of the above technical solutions have Mn 2+ Technical risks of heavy metal pollution caused by leakage. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a septic tank sewage treatment device to solve the problem that the prior art solutions have insufficient treatment capacity for high concentrations of ammonia nitrogen and saturated dissolved methane present in septic tank sewage, and there is the problem of secondary pollution caused by the leakage of heavy metal ions.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: a septic tank sewage treatment device is provided, comprising an inlet area, a sewage treatment unit and an outlet area; the sewage treatment unit comprises a supporting layer, a mixed filler layer and a surface layer from bottom to top, the inlet area is arranged on the supporting layer, and the outlet area is arranged on the surface layer; the filler of the supporting layer is rock, the filler of the mixed filler layer is pyrolusite and pyrite, and the filler of the surface layer is biochar; wetland plants are planted above the sewage treatment unit; the sewage treatment unit is inoculated with anaerobic methane oxidizing bacteria, dissimilatory manganese reducing bacteria and denitrifying bacteria.

[0007] The beneficial effects of the present invention are as follows: in the sewage treatment process, the organic matter in the sewage flowing through the mixed filler layer of pyrolusite and pyrite is anaerobic oxidized to carbon dioxide and removed, the ammonia nitrogen in the sewage is anaerobic oxidized to nitrogen and removed, the nitrate oxidized to ammonia nitrogen is reduced to nitrogen and removed, the soluble methane in the sewage is anaerobic oxidized to carbon dioxide and removed, the phosphate in the sewage is precipitated and retained and removed, and the Mn(IV) reduced to Mn 2+ The remaining small amounts of pollutants in the sewage are further adsorbed and removed by the top biochar layer. Wetland plants also absorb nitrogen, phosphorus, carbon dioxide, etc.

[0008] Among them, the ammonia nitrogen in the influent is oxidized to nitrogen gas and nitrate by manganese ammonia oxidizing microorganisms using Mn(Ⅳ) in pyrolusite as electron acceptor, and Mn(Ⅳ) is reduced to Mn 2+ The dissolved methane in the influent is oxidized to carbon dioxide by denitrifying anaerobic methane oxidizing bacteria using nitrate produced by manganese ammonia oxidation as an electron acceptor, and the nitrate is reduced to nitrogen gas at the same time; the nitrate that is not completely removed by the denitrifying anaerobic methane oxidation process is removed by the iron autotrophic denitrifying and sulfur autotrophic denitrifying microorganisms using Fe in pyrite as an electron acceptor. 2+ and S 2- The dissolved methane in the influent can also be oxidized to carbon dioxide by manganese-reducing anaerobic methane-oxidizing bacteria with Mn(Ⅳ) as the electron acceptor, and Mn(Ⅳ) is reduced to Mn 2+ ; Organic matter in the influent is oxidized to carbon dioxide using Mn(Ⅳ) as an electron acceptor by dissimilatory manganese-reducing bacteria and is completely discharged from the wetland system. This process can effectively prevent organic matter from accumulating inside the wetland to form blockages, while reducing endogenous methane production caused by anaerobic digestion due to organic matter accumulation; Phosphates and Mn in the influent 2+ and Fe 2+ The metal ions such as manganese ammonia oxidation, manganese-reduced anaerobic methane oxidation, and dissimilatory manganese reduction produced Mn 2+ It can react with phosphate in the influent and S in pyrite 2- Chemical precipitation can effectively prevent the 2+ and S 2- Secondary pollution caused by leakage.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows:

[0010] Furthermore, the height of the supporting layer is 5-10 cm, the height of the mixed filler layer is 45-55 cm, and the height of the surface layer is 8-13 cm.

[0011] The beneficial effect of adopting the above further technical solution is that the height of the mixed filler layer can maintain a good anaerobic environment inside the wetland.

[0012] Furthermore, the particle size of rock is 1.5~3 cm, the particle size of pyrolusite and pyrite is 1~2 cm, and the particle size of biochar is 0.8~1.2 cm.

[0013] The beneficial effects of adopting the above further technical solution are: the large-particle supporting layer filler can effectively prevent the bottom of the wetland from being blocked, and the small-particle surface filler can filter out most of the suspended matter to prevent the inside of the wetland from being blocked.

[0014] Furthermore, the rock is at least one of gravel, quartz or pebble.

[0015] Furthermore, the volume ratio of pyrolusite to the pyrite is 4:1.

[0016] The beneficial effect of adopting the above further technical solution is that the use of this volume ratio can enhance denitrification and the precipitation of divalent manganese ions while ensuring that the effect of manganese ore is not reduced.

[0017] Furthermore, the mixed filler layer is filled in a mixed manner of pyrolusite and pyrite.

[0018] Furthermore, the mixed filler layer adopts a segmented filling method with pyrite on the upper side and pyrolusite on the lower side.

[0019] Furthermore, wetland plants are emergent plants.

[0020] The beneficial effects of adopting the above further technical solution are: emergent plants have the functions of absorbing and assimilating pollutants and intercepting and filtering pollutants, and have stable storage of nitrogen and phosphorus, which can be easily removed by harvesting.

[0021] Further, the anaerobic methane oxidizing bacteria include denitrifying anaerobic methane oxidizing bacteria and manganese reducing anaerobic methane oxidizing bacteria, and the denitrifying bacteria include iron autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria;

[0022] The isolation and cultivation method of denitrifying anaerobic methane oxidizing bacteria is as follows:

[0023] The egg-shaped digester sludge of Jiguanshi Sewage Treatment Plant was placed in a sealed anaerobic culture bottle, and anaerobic influent was continuously pumped in by a peristaltic pump. The anaerobic influent contained nitrate nitrogen, trace elements, and saturated dissolved methane. When the cultured sludge could reduce the nitrate to below 5 mg / L within 6 hours, the culture was completed.

[0024] The isolation and culture method of manganese-reducing anaerobic methane-oxidizing bacteria is as follows:

[0025] The egg-shaped digester sludge of Jiguanshi Sewage Treatment Plant was placed in a closed anaerobic culture bottle, and the anaerobic influent was continuously pumped into the anaerobic influent through a peristaltic pump. The anaerobic influent contained nitrate nitrogen and trace elements as well as Mn 4+ , when the cultured sludge can reduce the nitrate to below 5 mg / L within 6 h, the culture is completed;

[0026] The isolation and culture method of dissimilatory manganese-reducing bacteria is as follows:

[0027] The egg-shaped digester sludge of Jiguanshi Sewage Treatment Plant was placed in a closed anaerobic culture bottle, and the anaerobic influent was continuously pumped into the anaerobic influent through a peristaltic pump. The anaerobic influent contained COD, trace elements and Mn 4+ , when the cultured sludge can reduce COD to below 30 mg / L within 6 hours, the culture is completed;

[0028] The isolation and cultivation method of iron autotrophic denitrifying bacteria is as follows:

[0029] The denitrification sludge from the Jiguanshi sewage treatment plant was placed in a sealed anaerobic culture bottle and continuously pumped into the anaerobic influent through a peristaltic pump. The anaerobic influent contained nitrate nitrogen and trace elements as well as Fe. 2+ , when the cultured sludge can reduce the nitrate to below 5 mg / L within 6 h, the culture is completed;

[0030] The isolation and cultivation method of sulfur autotrophic denitrifying bacteria is as follows:

[0031] The denitrification sludge from Jiguanshi Sewage Treatment Plant was placed in a sealed anaerobic culture bottle and continuously pumped into the anaerobic influent through a peristaltic pump. The anaerobic influent contained nitrate nitrogen, trace elements and S 2- When the cultured sludge can reduce the nitrate to below 5 mg / L within 6 hours, the culture is completed.

[0032] Another object of the present invention is to provide an application of the above-mentioned septic tank sewage treatment device in treating rural septic tank sewage.

[0033] The present invention has the following beneficial effects: the present invention uses pyrolusite (MnO2), pyrite (FeS2) and biochar as partition fillers for septic tank sewage treatment devices, and adopts a bottom-in and top-out water inlet method to maintain the anaerobic environment of the septic tank sewage treatment device. It can achieve efficient removal of organic matter, ammonia nitrogen, phosphate and soluble methane in the effluent of rural septic tanks, further alleviate the blockage of wetlands and prevent the generation of endogenous methane, and at the same time prevent the leakage of heavy metals to cause secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a sewage treatment device according to Example 2;

[0035] Figure 2The total nitrogen and ammonia nitrogen concentrations of the inlet and outlet water in Example 2 and Comparative Example 1 are shown in FIG.

[0036] Figure 3 The graphs are the changes of dissolved methane concentration in the inlet and outlet water in Example 2 and Comparative Example 1;

[0037] Figure 4 The graphs are the changes of phosphate concentrations of the inlet and outlet water in Example 2 and Comparative Example 1;

[0038] Figure 5 Mn is the effluent Mn in Example 2 and Comparative Example 2 2+ Concentration variation graph;

[0039] Figure 1 The bid number is:

[0040] 1. Water inlet valve; 2. Supporting layer; 3. Mixed filler layer; 4. Surface layer; 5. Water outlet valve; 6. Windmill grass. DETAILED DESCRIPTION

[0041] A septic tank sewage treatment device, such as Figure 1 As shown, it includes an inlet area, a sewage treatment unit and an outlet area; wherein the sewage treatment unit includes a supporting layer 2, a mixed filler layer 3 and a surface layer 4 from bottom to top, the inlet area is an inlet valve 1 located at the bottom of the supporting layer 2, and the outlet area is an outlet valve 5 located at the top of the surface layer 4.

[0042] The height of the supporting layer 2 is 5-10 cm, and it is filled with rocks (gravel, quartz, pebbles, etc.) with a particle size of about 1.5-3 cm. The large-particle supporting layer filler can effectively prevent the bottom of the wetland from being blocked; the height of the mixed filler layer 3 is 45-55 cm, and it is filled with pyrolusite and pyrite with a particle size of about 1-2 cm. The filling method is a mixed filling of pyrolusite and pyrite or a segmented filling of pyrite on top and pyrolusite on the bottom. The volume mixing ratio of pyrolusite to pyrite in both filling methods is 4:1. The height setting of the mixed filler layer 3 can maintain a good anaerobic environment inside the wetland. At the same time, this layer of filler is also the main occurrence area of ​​pollutant removal; the height of the surface layer 4 is 8-13 cm, and the filling particle size is 0.8-1.2 The biochar is about cm in diameter, and the small-particle surface filler can filter out most of the suspended matter and adsorb pollutants, further improving the water quality of the effluent; wetland plants are planted above the sewage treatment unit; the sewage treatment unit is inoculated with anaerobic methane oxidizing bacteria, dissimilatory manganese-reducing bacteria and denitrifying bacteria, which can be separated from the sewage treatment plant or the bacteria already available in the existing technology.

[0043] The principles and features of the present invention are described below in conjunction with the examples, which are only used to explain the present invention and are not intended to limit the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0044] Embodiment 1:

[0045] A mixed strain preparation for inoculation in a septic tank sewage treatment device, the preparation method is as follows:

[0046] (1) Bacterial isolation and culture

[0047] Isolation and culture of denitrifying anaerobic methane oxidizing bacteria: The egg-shaped digester sludge of the Jiguanshi sewage treatment plant was placed in a closed anaerobic culture bottle, and anaerobic influent was continuously pumped in through a peristaltic pump. The anaerobic influent contained 40 mg / L nitrate nitrogen and trace elements necessary for microbial growth as well as saturated dissolved methane. After a period of culture, the culture was completed when the cultured sludge could reduce the nitrate to below 5 mg / L within 6 hours.

[0048] Isolation and culture of manganese-reducing anaerobic methane-oxidizing bacteria: The egg-shaped digester sludge of the Jiguanshi sewage treatment plant was placed in a closed anaerobic culture bottle, and anaerobic influent was continuously pumped into the anaerobic influent through a peristaltic pump. The anaerobic influent contained 40 mg / L nitrate nitrogen and trace elements necessary for microbial growth, as well as 7 mmol / L Mn 4+ After a period of cultivation, when the cultured sludge can reduce the nitrate to below 5 mg / L within 6 hours, the cultivation is completed.

[0049] Isolation and culture of dissimilatory manganese-reducing bacteria: The egg-shaped digester sludge of the Jiguanshi sewage treatment plant was placed in a closed anaerobic culture bottle, and anaerobic influent was continuously pumped into the anaerobic influent through a peristaltic pump. The anaerobic influent contained 300 mg / L COD and trace elements necessary for microbial growth and 20 mmol / L Mn 4+ After a period of cultivation, when the cultured sludge can reduce COD to below 30 mg / L within 6 hours, the cultivation is completed.

[0050] Isolation and culture of iron autotrophic denitrifying bacteria: Denitrification sludge from Jiguanshi sewage treatment plant was placed in a closed anaerobic culture bottle, and anaerobic influent was continuously pumped into the bottle by a peristaltic pump. The anaerobic influent contained 40 mg / L nitrate nitrogen and trace elements necessary for microbial growth, as well as 14 mmol / L Fe 2+ After a period of cultivation, when the cultured sludge can reduce the nitrate to below 5 mg / L within 6 hours, the cultivation is completed.

[0051] Isolation and culture of sulfur autotrophic denitrifying bacteria: Denitrification sludge from Jiguanshi sewage treatment plant was placed in a closed anaerobic culture bottle, and anaerobic influent was continuously pumped into the bottle by a peristaltic pump. The anaerobic influent contained 40 mg / L nitrate nitrogen and trace elements necessary for microbial growth, as well as 7 mmol / L S 2- After a period of cultivation, when the cultured sludge can reduce the nitrate to below 5 mg / L within 6 hours, the cultivation is completed.

[0052] The types and amounts of trace elements necessary for microbial growth added during the above-mentioned culture process are shown in Table 1:

[0053] Table 1 Trace elements types and addition amounts

[0054]

[0055] (2) Mixing of bacterial strains

[0056] The denitrifying anaerobic methane oxidizing bacteria, manganese-reducing anaerobic methane oxidizing bacteria, dissimilatory manganese-reducing bacteria, iron-autotrophic denitrifying bacteria and sulfur-autotrophic denitrifying bacteria obtained by the above culture were mixed in equal volumes to obtain a mixed strain.

[0057] Embodiment 2:

[0058] A septic tank sewage treatment device, such as Figure 1 As shown, it includes the water inlet area, sewage treatment unit and water outlet area.

[0059] Among them, the sewage treatment unit is divided into three layers from bottom to top, namely the supporting layer 2, the mixed filler layer 3 and the surface layer 4; the water inlet area is the water inlet valve 1 located at the bottom of the supporting layer 2, and the water outlet area is the water outlet valve 5 located at the top of the surface layer 4.

[0060] The height of the supporting layer 2 is 8 cm, and it is filled with gravel with a particle size of about 2 cm. The large-particle supporting layer filler can effectively prevent the bottom of the wetland from being blocked; the height of the mixed filler layer 3 is 50 cm, and it is filled with pyrolusite and pyrite with a particle size of about 2 cm. The pyrolusite and pyrite are filled in a mixed manner, and the volume mixing ratio of pyrolusite to pyrite is 4:1. The height setting of the mixed filler layer 3 can maintain a good anaerobic environment inside the wetland. At the same time, this layer of filler is also the main occurrence area of ​​pollutant removal; the height of the surface layer 4 is 10 cm, and it is filled with biochar with a particle size of about 1 cm. The small-particle surface filler can filter out most of the suspended matter and adsorb pollutants, further improving the water quality of the effluent; the evergreen wetland emergent plant windmill grass 6 is planted above the sewage treatment unit.

[0061] During the process of filling the filler into the sewage treatment unit, the mixed bacteria cultured in Example 1 is injected until the bacterial solution is level with the filler surface for every 10 cm of filler. The sewage treatment device continuously takes in water from bottom to top, and the bacteria adhere to the filler surface to form a biofilm. Stable effluent quality means successful inoculation.

[0062] Embodiment 3:

[0063] A septic tank sewage treatment device, such as Figure 1 As shown, it includes the water inlet area, sewage treatment unit and water outlet area.

[0064] Among them, the sewage treatment unit is divided into three layers from bottom to top, namely the supporting layer 2, the mixed filler layer 3 and the surface layer 4; the water inlet area is the water inlet valve 1 located at the bottom of the supporting layer 2, and the water outlet area is the water outlet valve 5 located at the top of the surface layer 4.

[0065] The height of the supporting layer 2 is 5 cm, and it is filled with quartz with a particle size of about 1.5 cm. The large-particle supporting layer filler can effectively prevent the bottom of the wetland from being blocked; the height of the mixed filler layer 3 is 45 cm, and it is filled with pyrolusite and pyrite with a particle size of about 1 cm. The pyrolusite and pyrite are filled in a segmented filling method with pyrite on the top and pyrolusite on the bottom. The volume ratio of pyrolusite to pyrite is 4:1. The height setting of the mixed filler layer 3 can maintain a good anaerobic environment inside the wetland. At the same time, this layer of filler is also the main occurrence area of ​​pollutant removal; the height of the surface layer 4 is 13 cm, and it is filled with biochar with a particle size of about 1 cm. The small-particle surface filler can filter out most of the suspended matter and adsorb pollutants, further improving the water quality of the effluent; the evergreen wetland emergent plant windmill grass 6 is planted above the sewage treatment unit.

[0066] During the process of filling the filler into the sewage treatment unit, the mixed bacteria cultured in Example 1 is injected until the bacterial solution is level with the filler surface for every 10 cm of filler. The sewage treatment device continuously takes in water from bottom to top, and the bacteria adhere to the filler surface to form a biofilm. Stable effluent quality means successful inoculation.

[0067] Embodiment 4:

[0068] A septic tank sewage treatment device, such as Figure 1 As shown, it includes the water inlet area, sewage treatment unit and water outlet area.

[0069] Among them, the sewage treatment unit is divided into three layers from bottom to top, namely the supporting layer 2, the mixed filler layer 3 and the surface layer 4; the water inlet area is the water inlet valve 1 located at the bottom of the supporting layer 2, and the water outlet area is the water outlet valve 5 located at the top of the surface layer 4.

[0070] The height of the supporting layer 2 is 10 cm, and it is filled with pebbles with a particle size of about 3 cm. The large-particle supporting layer filler can effectively prevent the bottom of the wetland from being blocked; the height of the mixed filler layer 3 is 55 cm, and it is filled with pyrolusite and pyrite with a particle size of about 2 cm. The pyrolusite and pyrite are filled in a mixed manner, and the volume mixing ratio of pyrolusite to pyrite is 4:1. The height setting of the mixed filler layer 3 can maintain a good anaerobic environment inside the wetland. At the same time, this layer of filler is also the main occurrence area of ​​pollutant removal; the height of the surface layer 4 is 8 cm, and it is filled with biochar with a particle size of about 1 cm. The small-particle surface filler can filter out most of the suspended matter and adsorb pollutants, further improving the water quality of the effluent; the evergreen wetland emergent plant windmill grass 6 is planted above the sewage treatment unit.

[0071] During the process of filling the filler into the sewage treatment unit, the mixed bacteria cultured in Example 1 is injected until the bacterial solution is level with the filler surface for every 10 cm of filler. The sewage treatment device continuously takes in water from bottom to top, and the bacteria adhere to the filler surface to form a biofilm. Stable effluent quality means successful inoculation.

[0072] Comparative Example 1:

[0073] A septic tank sewage treatment device, as described below:

[0074] The filler of the mixed filler layer 3 in Example 2 is replaced with gravel with a particle size of about 2 cm, and the rest is the same as Example 2.

[0075] Comparative Example 2:

[0076] A sewage treatment device using a septic tank, as described below:

[0077] The filler of the mixed filler layer 3 in Example 2 is replaced with a pyrolusite filler with a particle size of about 2 cm, and the rest is the same as Example 2.

[0078] Experimental Example 1:

[0079] The septic tank sewage treatment devices prepared in Examples 2-4 of the present invention have similar performances. Taking Example 2 as an example, the performance of the septic tank sewage treatment device is explained.

[0080] The same treatment was performed on Example 2-4, Comparative Example 1 and Comparative Example 2, and the specific operation process was as follows:

[0081] A septic tank sewage treatment device with a diameter of 110 mm and a height of 70 cm was constructed to treat sewage from a rural septic tank. The sewage flowed into the septic tank sewage treatment device from the bottom water inlet valve 1, and flowed from bottom to top through the supporting layer 2, the mixed filler layer 3 and the surface layer 4. The sewage was purified inside the septic tank sewage treatment device. The hydraulic retention time of the sewage inside the septic tank sewage treatment device was controlled by controlling the flow rate. The hydraulic retention time was 3 days. The sewage treatment device operated continuously for 50 days. Finally, the purified sewage overflowed from the outlet valve 5.

[0082] The effluent quality was monitored every 10 days, and the concentrations of ammonia nitrogen, dissolved methane, phosphate and Mn in the effluent were measured. 2+ The concentration was tested.

[0083] Figure 2 The mixed filler wetland device of Example 2 and the gravel wetland device of Comparative Example 1 show the removal effect of nitrogen in sewage. The influent contains only ammonia nitrogen, and the concentration of ammonia nitrogen is the concentration of total nitrogen. As shown in the figure, the concentration of total nitrogen in the influent is about 36.42 mg / L, the nitrogen removal rate of the device in Comparative Example 1 is about 13%, and the nitrogen removal rate of the device in Example 2 reaches more than 85%; the ammonia nitrogen discharge concentration in the effluent of Example 2 is reduced by more than 80% compared with that of Comparative Example 1.

[0084] Figure 3 The mixed filler wetland device of Example 2 and the gravel wetland device of Comparative Example 1 show the removal effect of dissolved methane in sewage. The removal rate of dissolved methane by the device in Comparative Example 1 is about 7%, while the removal rate of dissolved methane by the device in Example 2 reaches more than 86%.

[0085] Figure 4 The mixed filler wetland device of Example 2 and the gravel wetland device of Comparative Example 1 show the removal effect of phosphate in sewage. The phosphate removal rate of the device in Comparative Example 1 is about 12%, while the phosphate removal rate of the device in Example 2 reaches an average of about 95%.

[0086] Figure 5 The Mn in the effluent of the mixed filler wetland device of Example 2 and the manganese ore wetland device of Comparative Example 2 2+ Comparison of concentration changes: Mn in the effluent of the device in comparative example 2 2+ The concentration of Mn in the effluent of the device in Example 2 is about 22.63 mg / L. 2+ The concentration of Mn is about 0.26 mg / L. 2+ It has a significant reduction effect on leakage.

[0087] It can be seen from the above experimental data that the present invention has a good purification effect on sewage, the concentration of each pollutant in the effluent is significantly reduced, and while achieving high removal rates of methane, nitrogen and phosphorus, it prevents the leakage of heavy metal ions and avoids secondary pollution.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A septic tank sewage treatment device, characterized in that: It includes an inlet area, a sewage treatment unit and an outlet area; the sewage treatment unit includes a supporting layer, a mixed filler layer and a surface layer from bottom to top, the height of the supporting layer is 5-10 cm, the height of the mixed filler layer is 45-55 cm, and the height of the surface layer is 8-13 cm; the inlet area is arranged on the supporting layer, and the outlet area is arranged on the surface layer; the filler of the supporting layer is rock, the filler of the mixed filler layer is pyrolusite and pyrite, the volume ratio of the pyrolusite to the pyrite is 4:1, and the filler of the surface layer is biochar; wetland plants are planted above the sewage treatment unit; the sewage treatment unit is inoculated with anaerobic methane oxidizing bacteria, dissimilatory manganese reducing bacteria, denitrifying bacteria and manganese ammonia oxidizing microorganisms, the anaerobic methane oxidizing bacteria include denitrifying anaerobic methane oxidizing bacteria and manganese reducing anaerobic methane oxidizing bacteria, and the denitrifying bacteria include iron autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

2. The septic tank sewage treatment device according to claim 1, characterized in that: The particle size of the rock is 1.5-3 cm, the particle size of the pyrolusite and pyrite is 1-2 cm, and the particle size of the biochar is 0.8-1.2 cm.

3. The septic tank sewage treatment device according to claim 2, characterized in that: The rock is at least one of gravel, quartz and pebble.

4. The septic tank sewage treatment device according to claim 1, characterized in that: The mixed filler layer is filled in a mixed manner of pyrolusite and pyrite.

5. The septic tank sewage treatment device according to claim 1, characterized in that: The mixed filler layer adopts a segmented filling method with pyrite on the top and pyrolusite on the bottom.

6. The septic tank sewage treatment device according to claim 1, characterized in that: The wetland plants are emergent plants.

7. Application of the septic tank sewage treatment device according to any one of claims 1 to 6 in treating rural septic tank sewage.

Images