Rural domestic sewage treatment device and process method

Abstract

The present application relates to a kind of rural domestic sewage treatment device, including intercepting sewage well, septic tank, hydrolysis adjustment pool, intercepting sewage well is provided with overflow pipe and hydrolysis adjustment pool connection, hydrolysis adjustment pool is provided with grid well, hydrolysis adjustment pool is provided with suspended filler and lifting pump, in situ nitrification-denitrification pool is provided with biological membrane suspended bed filler, bottom is equipped with microporous aerator, vent valve, effluent of in situ nitrification-denitrification pool is distributed to high-density sedimentation tank. High-density sedimentation tank is provided with mixer, honeycomb inclined pipe, filter brush, top is provided with overflow weir, bottom is equipped with hopper and electric valve. Process flow is simple, operation and maintenance is simple, effluent quality is stable, process method and device with low operating cost, short start-up time, fundamentally solve the problem existing in the current rural sewage terminal, and the management level corresponding with rural domestic sewage treatment is matched.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a rural domestic sewage treatment device and process. Background Technology

[0002] Currently, most villages in the southeastern region have relatively good economic conditions, and sewage collection and treatment facilities have been constructed and are in the operation and maintenance phase. The current status of rural sewage terminal facilities and their operation and maintenance is as follows:

[0003] The impact of drainage system on wastewater quality and quantity: Combined sewer systems have a larger volume of water and a lower concentration during rainy days; separate sewer systems, due to the incomplete sealing of pipe networks and manholes, have a slightly larger volume of water and a slightly lower concentration during rainy days.

[0004] Large variation coefficient: The amount of rural sewage discharge is similar to the living patterns of residents, with more discharge in the morning and evening than during the day, and less discharge at night, or even interruption. The water volume changes significantly, and sewage discharge is discontinuous, characterized by large fluctuations.

[0005] Low water quality concentration: In most cases, the concentration is lower than that of urban sewage, CODCr≤200mg / L, NH3-N≤50mg / L, SS≤100mg / L.

[0006] Emission standards

[0007] In most areas of Zhejiang Province, the standard for terminal agricultural wastewater discharge is the Class II standard of the "Water Pollutant Discharge Standard for Centralized Rural Domestic Wastewater Treatment Facilities" (DB33 / 973—2021), which specifies that the main indicators are CODCr ≤ 100 mg / L, SS ≤ 30 mg / L, NH3-N ≤ 25(15) mg / L, and TP ≤ 3(2) mg / L. Special areas implement the Class I standard, which specifies that the main indicators are CODCr ≤ 60 mg / L, SS ≤ 20 mg / L, NH3-N ≤ 8(15) mg / L, and TP ≤ 2(1) mg / L.

[0008] Process flow and advantages and disadvantages

[0009] Currently, most terminal processes employ the following five methods: ① A / A / O + constructed wetland; ② A / O + constructed wetland; ③ Anoxic + contact oxidation + constructed wetland; ④ MBR process; ⑤ Circulating biological filter (see appendix for details). Figure 3-7 ).

[0010] The main problems in the operation and maintenance of the above five commonly used rural wastewater treatment processes are as follows:

[0011] Processes ①, ②, ③, and ④ are designed according to the highest concentration value (COD≤400mg / L) in the design specifications, with a certain margin. Therefore, the wastewater retention time is long, the entire process is in the extended aeration stage, the sludge age is long, the sludge activity is low, the amount of residual sludge is small, and there is no residual sludge discharged from the terminal all year round.

[0012] Phosphorus removal: Processes ①, ②, and ③ mainly rely on constructed wetlands for phosphorus removal. The internal packing material of constructed wetlands needs to be replaced every 3-5 years on average, and the replacement cost is high. Although process ① has an anaerobic unit, the residual sludge from the secondary sedimentation tank is discharged to the septic tank, and the effluent from the septic tank re-enters the system for circulation. The system does not have the conditions for timely and quantitative discharge of sludge, resulting in very little actual phosphorus removal effect of the anaerobic tank. Processes ④ and ⑤ will retain most of the suspended phosphorus during the filtration process, but chemical additives are needed to assist in the removal of soluble phosphorus.

[0013] Operating costs and maintenance workload:

[0014] Process ① has 4 water pumps, 2 blowers, and 2 sets of mixing facilities. Sludge from the septic tank is regularly pumped out, constructed wetland plants are regularly harvested and disposed of, and constructed wetland filler is regularly replaced. The key points of the process are sludge return flow, discharge volume, and aeration volume.

[0015] Processes ② and ③ have 4 water pumps, 2 blowers, and 1 set of mixing equipment. Septic tank sludge is regularly pumped out, constructed wetland plants are regularly harvested and disposed of, and constructed wetland filler is regularly replaced. The key points of the process are sludge return flow rate and discharge rate. Although process ③ is a contact oxidation tank, in actual operation, whether it is a suspended filler or a suspended filler, sludge needs to be returned to the secondary sedimentation tank to reduce the loss of activated sludge. The key points of the process are sludge return flow rate, discharge rate, and aeration rate.

[0016] Process ④ requires 7 water pumps, 2 blowers, 1 set of mixing facilities, 1 set of membrane cleaning system (including 2 sets of dosing devices), 1 set of phosphorus removal dosing device, and 1 set of MBR unit. It requires highly skilled operators. Once the membrane is clogged, it is difficult to completely restore it through cleaning. The replacement cost of membrane modules is expensive. At the same time, because the secondary sedimentation tank is omitted, the sludge concentration in the membrane tank is high and the sludge aging degree is high. The key points of the process are sludge return flow rate, discharge rate, aeration rate, membrane permeate flow rate and backwashing frequency, and dosing dosage.

[0017] Process ⑤ utilizes high-flow-rate circulation and multiple-cycle purification, involving multiple biological and filtration processes. When the inflow is low, the pollutant concentration is reduced to a low level during multiple cycles, approximately 20 cycles per day. When the inflow is high, the pollutants are diluted and discharged to the effluent tank via overflow. This system has 7 water pumps and 1 phosphorus removal dosing system. Natural ventilation eliminates the need for a blower. However, odors are generated nearby during the drip filtration process, requiring on-site fencing, which increases the land area and construction costs. The power of the circulating water pumps is also significantly increased, resulting in higher energy consumption.

[0018] System debugging startup time:

[0019] After the initial addition of activated sludge, the commissioning time for these five processes is 15-30 days. After the system is shut down, the restart time for processes ④ and ⑤ is shorter.

[0020] Impact load resistance:

[0021] Process ④, due to the quantitative filtration function of the MBR membrane, has almost no ability to resist shock loads on water volume, and often overflows into the tank. The other processes are slightly better, but the effluent quality will deteriorate when the flow rate increases.

[0022] Based on the above analysis, the main challenge in the operation and maintenance of rural domestic sewage terminals lies in the lack of personnel with professional knowledge and skills, making it difficult to perform precise and effective maintenance and management for even slightly complex processes. Therefore, local governments prioritize villages with the conditions to connect to the municipal sewage network for unified treatment. However, connection to the network requires villages to be located close to the municipal network, meet elevation requirements, have sufficient treatment capacity at their sewage treatment plants, and have water quality concentrations within the required range for connection.

[0023] Connecting wastewater to the mains also brings two problems: First, if the concentration is too low, it will increase the amount of denitrifying nutrients to be added, increasing the operating costs of the wastewater treatment plant; second, wastewater in many places needs to be pumped up, and if it is pumped up multiple times, it will increase the transportation costs. Summary of the Invention

[0024] The purpose of this invention is to provide a rural domestic sewage treatment device and process to solve the problems mentioned in the background art.

[0025] To solve the above-mentioned technical problems, the present invention is achieved through the following technical measures: a rural domestic sewage treatment device, characterized in that: it includes a intercepting well, the bottom of which is provided with an intercepting pipe connected to a septic tank, the septic tank being connected to a hydrolysis regulating tank via a pipe, an overflow pipe being provided at the middle height of the intercepting well and connected to the hydrolysis regulating tank, the hydrolysis regulating tank being provided with a bar screen well, and the hydrolysis regulating tank being provided with suspended packing and a lift pump; the lift pump is connected to a pre-settling return tank via a pipeline, the pre-settling return tank being provided with settling aid packing and a first sludge hopper, the upper part of the pre-settling return tank being provided with an overflow weir, and the sludge in the first sludge hopper of the pre-settling return tank being periodically transported to the septic tank via a first electric valve and a sludge pipe; the overflow weir is provided with... Wastewater enters the in-situ nitrification-denitrification tank through the water passage K1. A biofilm suspended bed packing material is installed in the middle of the in-situ nitrification-denitrification tank. A microporous aerator is installed at the bottom of the in-situ nitrification-denitrification tank. An vent valve is installed at the bottom of the in-situ nitrification-denitrification tank, and aged biofilm is periodically discharged to the septic tank through a sludge pipe. The effluent from the in-situ nitrification-denitrification tank is distributed to a high-density sedimentation tank through the water passage K5 via a distribution pipe. The high-density sedimentation tank is equipped with a mixer, honeycomb inclined tubes, and filter brushes. A top overflow weir for discharging effluent is installed at the top of the high-density sedimentation tank. A second electric valve is installed in the second sludge hopper at the bottom of the high-density sedimentation tank, and phosphorus-containing sludge is transported to the sludge tank through a sludge discharge pipe. The supernatant from the sludge tank overflows to the septic tank through the sludge pipe.

[0026] Compared with the prior art, the advantages of the present invention are: simple process flow, easy operation and maintenance, stable effluent quality, low operating cost, and short start-up time. The process method and device are suitable for centralized and decentralized treatment of rural domestic sewage in Southeast China, treatment of domestic sewage in tourist attractions, and sewage treatment with similar properties and treatment requirements. It fundamentally solves the current problems of agricultural sewage treatment and matches the corresponding management level of rural domestic sewage treatment.

[0027] As an improvement of the present invention, the booster pump is provided with a protective cover. The purpose of this design is to prevent the packing from clogging the booster pump.

[0028] As an improvement to the present invention, a valve and a flow meter are installed on the pipeline. The purpose of this design is to adjust the flow rate of the flow meter by means of the valve.

[0029] As an improvement of this invention, the in-situ nitrification-denitrification tank is configured with four groups, each equipped with a water passage hole. Specifically, water passage hole K2 of group 1 is located at the bottom of the in-situ nitrification-denitrification tank, water passage hole K3 of group 2 is located at the top of the in-situ nitrification-denitrification tank, water passage hole K4 of group 3 is located at the bottom of the in-situ nitrification-denitrification tank, and water passage hole K5 of group 4 is located at the top of the in-situ nitrification-denitrification tank. The purpose of this design is to create gravity flow of the effluent through the staggered water passage holes. The more groups of in-situ nitrification-denitrification tanks there are, the better the purification effect.

[0030] As an improvement of the present invention, the microporous aerator is supplied with air by a blower. The purpose of choosing this design is: simplicity and practicality.

[0031] As an improvement of the present invention, an air regulating valve is provided in the intermediate air path of the microporous aerator. The purpose of this design is to use the air regulating valve to adjust the air volume of each compartment.

[0032] This invention also provides a rural domestic sewage treatment process, comprising the following steps:

[0033] 1. Domestic sewage is collected through the pipe network and enters the intercepting well. During the dry season when the water volume is low, all sewage is intercepted and enters the septic tank through the intercepting pipe. During the rainy season when the water volume is large, sewage exceeding the capacity of the septic tank enters the grit chamber through the overflow pipe.

[0034] 2. After larger floating and suspended solids are intercepted, the wastewater in the grit chamber flows by gravity into the hydrolysis equalization tank. The hydrolysis equalization tank is filled with suspended packing material. After the suspended packing material is loaded with biofilm, its specific gravity is close to that of water, so it can be freely suspended in the water. This makes full use of the residence time of the wastewater in the hydrolysis equalization tank, so that some of the suspended solids and organic matter in the wastewater can be hydrolyzed, acidified and removed at this stage.

[0035] 3. When the wastewater in the hydrolysis equalization tank reaches a certain level, start the lift pump and transport it through the lift pipeline. After being measured by the flow meter, it enters the first sludge hopper of the pre-sedimentation return tank. The flow rate of the flow meter can be adjusted by the valve.

[0036] 4. The pre-settling and return tank is equipped with sedimentation aids and a first sludge hopper. The sedimentation aids can be honeycomb inclined tubes, inclined plates, elastic packing, hard brushes, etc. The upper part of the pre-settling and return tank is equipped with an overflow weir. After water collection, it flows by gravity through the water passage K1 to the in-situ nitrification-denitrification tank. There are four sets of in-situ nitrification-denitrification tanks, namely 1#, 2#, 3# and 4#. The four sets of in-situ nitrification-denitrification tanks are equipped with alternating upper and lower water passages K1, K2, K3, K4 and K5.

[0037] 5. The in-situ nitrification-denitrification tank is equipped with an aerobic biofilm suspended bed packing material. The biofilm suspended bed packing material has a porous structure and is hydrophilically modified. The material is one of polyurethane, volcanic rock, or microporous packing. Each cell of the in-situ nitrification-denitrification tank is equipped with a microporous aerator at the bottom. The oxygen volume is regulated by an air regulating valve. The required oxygen is supplied by a blower. Each cell of the in-situ nitrification-denitrification tank is equipped with a vent valve at the bottom, and the aged biofilm is periodically discharged into the septic tank through a sludge pipe.

[0038] 6. The effluent from the in-situ nitrification-denitrification tank is distributed to the upper part of the second sludge hopper of the high-density sedimentation tank through the water passage K5 and the water distribution pipe for phosphorus removal and sludge-water separation. A mixer is installed on the water distribution pipe, and a dosing pipe is installed at the inlet of the mixer. A high-efficiency phosphorus removal agent is added through the phosphorus removal dosing device. The high-density sedimentation tank is equipped with a double-layer anti-clogging and sedimentation-aiding packing structure, which also has an adsorption function. A filter brush is installed at the bottom and a honeycomb inclined tube is installed at the top to complete the two processes of contact interception and adsorption. It is equivalent to a sedimentation-contact filtration-adsorption composite tank, which is more efficient, improves the phosphorus removal rate, and reduces the amount of chemicals used. The effluent is discharged after meeting the standards through the top overflow weir.

[0039] 7. The sludge in the first sludge hopper of the pre-settling and return tank is periodically transported to the septic tank through the first electric valve and sludge pipe, forming an internal circulation of hydrolysis acidification and anaerobic bacteria: The process is as follows: pre-settling and return tank → septic tank → hydrolysis equalization tank → pre-settling and return tank. The second sludge hopper at the bottom of the high-density sedimentation tank is equipped with a second electric valve, which transports phosphorus-containing sludge to the sludge tank through the sludge discharge pipe. The supernatant of the sludge tank overflows into the septic tank through the sludge pipe. The sludge in the septic tank and sludge tank is periodically pumped out or dewatered by a mobile dewatering device and then transported off-site for disposal.

[0040] As an improvement of the present invention, the total retention time of the in-situ nitrification-denitrification tank is 10-12h, and the dosage of phosphorus removal agent is 10-15mg / L. The purpose of selecting this design is to achieve the first-class emission standard.

[0041] As an improvement of the present invention, the total retention time of the in-situ nitrification-denitrification tank is 8-10 hours, and the dosage of phosphorus removal agent is 5-10 mg / L. The purpose of selecting this design is to achieve the secondary discharge standard. Attached Figure Description

[0042] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0043] In the attached diagram:

[0044] Figure 1 This is a schematic diagram of the rural domestic sewage treatment device described in this invention.

[0045] Figure 2 This is a process flow diagram of rural domestic sewage treatment according to the present invention.

[0046] Figure 3 This is a process flow diagram of the A / A / O+ constructed wetland described in this invention.

[0047] Figure 4 This is a process flow diagram of the A / O+ constructed wetland described in this invention.

[0048] Figure 5 This is a process flow diagram of the anoxic + contact oxidation + constructed wetland described in this invention.

[0049] Figure 6 This is a process flow diagram of the MBR described in this invention.

[0050] Figure 7 This is a process flow diagram of the circulating biological filter described in this invention.

[0051] Explanation of reference numerals in the attached diagram: 1. Interception well; 2. Interception pipe; 3. Overflow pipe; 4. Septic tank; 5. Bar screen well; 6. Hydrolysis equalization tank; 7. Suspended packing; 8. Lift pump; 9. Protective cover; 10. Pipeline; 11. Flow meter; 12. Valve; 13. Pre-settling and return tank; 14. Auxiliary settling packing; 15. First sludge hopper; 16. First electric valve; 17. Sludge pipe; 18. Overflow weir; 19. In-situ nitrification-denitrification tank; 2 0. Biofilm suspended bed packing material; 21. Blower; 22. Microporous aerator; 23. Air regulating valve; 24. Vent valve; 25. High-density sedimentation tank; 26. Second sludge hopper; 27. Water distribution pipe; 28. Mixer; 29. ​​Chemical dosing pipe; 30. Phosphorus removal dosing device; 31. Filter brush; 32. Honeycomb inclined tube; 33. Top overflow weir; 34. Second electric valve; 35. Sludge discharge pipe; 36. Sludge tank; 37. Integrated device. Detailed Implementation

[0052] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0053] Example 1

[0054] Please refer to Figure 1 -7. Among them, Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 These are five existing processes commonly used for rural wastewater treatment.

[0055] This invention provides a rural domestic sewage treatment process, comprising the following steps:

[0056] 1. Domestic sewage is collected through the pipe network and enters the intercepting well 1. During the dry season when the water volume is low, all sewage is intercepted and enters the septic tank 4 through the intercepting pipe 2. During the rainy season when the water volume is large, sewage exceeding the capacity of the septic tank 4 enters the grit well 5 through the overflow pipe 3.

[0057] 2. After intercepting larger floating and suspended solids, the wastewater in the grit chamber 5 flows by gravity into the hydrolysis equalization tank 6. The hydrolysis equalization tank 6 is filled with suspended packing material 7. After the suspended packing material 7 is loaded with biofilm, its specific gravity is close to that of water, and it can be freely suspended in the water. This makes full use of the residence time of the wastewater in the hydrolysis equalization tank 6, so that some of the suspended solids and organic matter in the wastewater can be hydrolyzed, acidified and removed at this stage.

[0058] 3. When the wastewater in the hydrolysis equalization tank 6 reaches a certain level, the lift pump 8 is started. After being transported through the lift pipeline 10 and metered by the flow meter 11, the wastewater enters the area above the first sludge hopper 15 of the pre-settling return tank 13. The flow rate of the flow meter 11 can be adjusted by the valve 12. To prevent the packing material from clogging the lift pump 8, a protective cover 9 is installed outside the lift pump 8.

[0059] 4. The pre-settling reflux tank 13 is equipped with a settling aid packing 14 and a first sludge hopper 15. The settling aid packing 14 can be a honeycomb inclined tube, inclined plate, elastic packing, hard brush, etc.

[0060] The pre-sedimentation and return tank 13 is equipped with an overflow weir 18 at the top. After water collection, it flows by gravity through the water passage K1 into the in-situ nitrification-denitrification tank 19. The in-situ nitrification-denitrification tank 19 is equipped with alternating upper and lower water passages K1, K2, K3, K4, and K5.

[0061] 5. The in-situ nitrification-denitrification tank 19 is divided into 4 compartments and is equipped with a biofilm suspended bed packing material 20 carrying highly efficient aerobic bacteria. The biofilm suspended bed packing material 20 has a porous structure and has been hydrophilically modified, such as polyurethane, volcanic rock, microporous packing material, etc.

[0062] Each compartment of the in-situ nitrification-denitrification tank 19 is equipped with a microporous aerator 22 and an air regulating valve 23 at the bottom, and the oxygen required by the system is supplied by a blower 21. The microporous aerator 22 can be disc-shaped or tubular, and the air regulating valve 23 is used to regulate the air volume of each compartment.

[0063] Each compartment of the in-situ nitrification-denitrification tank 19 is equipped with a vent valve 24 at the bottom, through which the aged biofilm is periodically discharged into the septic tank 4 via the sludge pipe 17.

[0064] 6. The effluent from the in-situ nitrification-denitrification tank 19 is distributed to the upper part of the second sludge hopper 26 of the high-density sedimentation tank 25 through the water passage K5 and the water distribution pipe 27 for phosphorus removal and sludge-water separation.

[0065] A mixer 28 is installed on the water distribution pipe 27, and a dosing pipe 29 is installed at the inlet of the mixer 28. A high-efficiency phosphorus removal agent is added through the phosphorus removal dosing device 30.

[0066] The high-density sedimentation tank 25 is equipped with a double-layer anti-clogging and sedimentation-aiding packing material 14 structure, which also has an adsorption function. The bottom is equipped with a filter brush 31 and the top is equipped with honeycomb inclined tubes 32 to complete the two processes of contact interception and adsorption. It is equivalent to a sedimentation-contact filtration-adsorption composite tank, which is more efficient, improves the phosphorus removal rate, and reduces the dosage of chemicals. The effluent is discharged after meeting the standards through the top overflow weir 33.

[0067] 7. System sludge removal:

[0068] The sludge in the first sludge hopper 15 of the pre-settling return tank 13 is periodically transported to the septic tank 4 through the first electric valve 16 and sludge pipe 17, forming an internal circulation of hydrolysis acidification and anaerobic bacteria: pre-settling return tank 13 → septic tank 4 → hydrolysis equalization tank 6 → pre-settling return tank 13.

[0069] The second sludge hopper 26, located at the bottom of the high-density sedimentation tank 25, is equipped with a second electric valve 34, which transports phosphorus-containing sludge to the sludge tank 36 through the sludge discharge pipe 35. The supernatant of the sludge tank 36 overflows into the septic tank 4 through the sludge pipe 17.

[0070] The sludge in septic tank 4 and sludge tank 36 is periodically pumped out or dewatered using a mobile dewatering device before being transported off-site for disposal.

[0071] 8. Effluent water quality and phosphorus removal system:

[0072] The effluent from this system meets the Class I standard of the "Water Pollutant Discharge Standard for Centralized Rural Domestic Sewage Treatment Facilities" (DB33 / 973—2021), and the TN removal rate can reach 20%-30%.

[0073] When implementing secondary standards, the dosage of phosphorus removal agents can be reduced and the system residence time can be decreased.

[0074] Based on the system's operation and testing data in the project, the total retention time of the in-situ nitrification-denitrification tank 19 is 10-12 hours, and the phosphorus removal agent dosage is 10-15 mg / L, which can meet the first-class standard; the total retention time of the in-situ nitrification-denitrification tank 19 is 8-10 hours, and the phosphorus removal agent dosage is 5-10 mg / L, which can meet the second-class standard.

[0075] Coordination of the phosphorus removal process with the surrounding environment: Planting fast-growing, phosphorus-removing floating plants on the top of the pool can assist in phosphorus removal, prevent moss growth on the walls of the exposed equipment, and ensure harmony with the surrounding environment.

[0076] System Control: This system has relatively few operating components, as described below:

[0077] Booster pump 8: A total of 2 units, 1 in use and 1 on standby, which will start and stop automatically according to the liquid level.

[0078] Fan 21: A total of 2 units, 1 in use and 1 on standby, linked with booster pump 8.

[0079] One set of phosphorus removal chemical dosing device 30, linked with booster pump 8. Chemicals are prepared periodically.

[0080] The first electric valve is 16 units, controlled by a timer.

[0081] The second electric valve is 34 units, controlled by a timer.

[0082] This invention provides a rural domestic sewage treatment device.

[0083] In the embodiments of this invention application, please refer to Figure 1 and Figure 2 A rural domestic sewage treatment device includes a sewage interception well 1. A sewage interception pipe 2 is installed at the bottom of the sewage interception well 1, connecting it to a septic tank 4. The septic tank 4 is connected to a hydrolysis regulating tank 6 via a pipe. An overflow pipe 3 is installed at the middle of the sewage interception well 1, connecting it to the hydrolysis regulating tank 6. The hydrolysis regulating tank 6 is equipped with a bar screen well 5 and contains suspended packing material 7 and a lift pump 8. The lift pump 8 is connected to a pre-settling return tank 13 via a pipe 10. The pre-settling return tank 13 contains settling aid packing material 14 and a first sludge hopper 15. An overflow weir 18 is provided at the top of the pre-settling return tank 13. Sludge in the first sludge hopper 15 of the pre-settling return tank 13 is periodically transported to the septic tank 4 via a first electric valve 16 and a sludge pipe 17. The overflow weir 18 has a water passage hole for allowing sewage to enter an in-situ nitrification-denitrification tank 19. K1, the in-situ nitrification-denitrification tank 19 is provided with a biofilm suspended bed packing 20 in the middle, the bottom of the in-situ nitrification-denitrification tank 19 is provided with a microporous aerator 22, the bottom of the in-situ nitrification-denitrification tank 19 is provided with a vent valve 24, and the aged biofilm is periodically discharged to the septic tank 4 through the sludge pipe 17; the effluent from the in-situ nitrification-denitrification tank 19 is distributed to the high-density sedimentation tank 25 through the water distribution pipe 27 via the water passage K5, the high-density sedimentation tank 25 is provided with a mixer 28, honeycomb inclined tube 32, and filter brush 31, the top of the high-density sedimentation tank 25 is provided with a top overflow weir 33 for discharging water, the second sludge hopper 26 located at the bottom of the high-density sedimentation tank 25 is provided with a second electric valve 34, and the phosphorus-containing sludge is transported to the sludge tank 36 through the sludge discharge pipe 35, and the supernatant of the sludge tank 36 overflows to the septic tank 4 through the sludge pipe 17.

[0084] Among them, the phosphorus removal dosing device 30, the blower 21, and the in-situ nitrification-denitrification tank 19 are integrated into one device, forming an integrated device 37.

[0085] Furthermore, the lift pump 8 is provided with a protective cover 9 to prevent the packing from clogging the lift pump 8.

[0086] Furthermore, the pipeline 10 is equipped with a valve 12 and a flow meter 11, and the flow rate of the flow meter 11 is adjusted by the valve 12.

[0087] Furthermore, the in-situ nitrification-denitrification tank 19 is equipped with four sets, each with a water passage. The water passage K2 of set 1 is located at the bottom of the tank 19, the water passage K3 of set 2 is located at the top, the water passage K4 of set 3 is located at the bottom, and the water passage K5 of set 4 is located at the top. This staggered design of the water passages creates a gravity-flow system for the effluent. The more sets of in-situ nitrification-denitrification tanks 19 there are, the better the cleaning effect.

[0088] Furthermore, the microporous aerator 22 is supplied with air by the blower 21.

[0089] Furthermore, an air regulating valve 23 is provided in the intermediate air path of the microporous aerator 22, which is used to regulate the air volume of each compartment.

[0090] The beneficial effects of this invention are as follows:

[0091] This invention develops a process and apparatus that features a simple flow, easy operation and maintenance, stable effluent quality, low operating costs, and short start-up time (only 2-3 days). It is suitable for centralized and decentralized treatment of rural domestic sewage in Southeast China, treatment of domestic sewage from tourist attractions, and sewage treatment with similar properties and requirements. It fundamentally solves the current problems in rural sewage treatment and matches the corresponding management level of rural domestic sewage treatment.

[0092] The innovative aspects of this invention:

[0093] The process flow is simple and easy to operate and maintain: the main process adopts "hydrolysis equalization tank 6 → pre-settling and return tank 13 → in-situ nitrification-denitrification tank 19 → high-density sedimentation tank 25", abbreviated as "HOP three-stage process"; it makes full use of the residence time of wastewater in the equalization tank, and the equalization tank is also included in the treatment process; the pre-settling and return tank 13 is equipped with suspended hydrolysis packing; the in-situ nitrification-denitrification tank 19 is set as a ≥3-stage suspended bed or fluidized bed mode; the high-density sedimentation tank 25 is set as a double-layer anti-clogging structure, which also has an adsorption function; the pre-flocculation hydrolysis sedimentation tank and the high-density sedimentation tank 25 are equipped with sludge hoppers and electric sludge discharge valves, and the in-situ nitrification-denitrification tank 19 has a flat bottom and a manual vent valve 24. See the process flow diagram for details. Figure 2 .

[0094] Application of High-Efficiency Microbial Communities and Porous Carriers: Highly active microorganisms with strong wastewater decomposition capabilities, selected from nature, are attached to porous media such as polyurethane, volcanic rock, and microporous packing materials. The surface of the porous packing materials requires special hydrophilic treatment to improve the attachment efficiency of the microbial community. Porous media not only provide a habitat for microbial growth but also create an anoxic-aerobic microenvironment in the aerobic reactor, providing the reaction conditions for in-situ nitrification and denitrification of nitrogen-containing organic matter.

[0095] The equalization tank is "multi-purpose": it makes full use of the residence time of sewage in the equalization tank, adds the function of hydrolysis and acidification, and considers it as a process treatment unit. Together with the pre-settling return tank 13 and septic tank 4, it forms a facultative and anaerobic microbial circulation system, so that some organic matter and suspended solids are degraded and removed in this part, effectively reducing the residence time and energy consumption of the aerobic part.

[0096] No separate anoxic tank is required: the in-situ nitrification-denitrification tank 19 creates an anoxic-aerobic microenvironment in the aerobic reaction tank, eliminating the need for a separate anoxic tank, mixed liquor recirculation, and sludge recirculation.

[0097] No need to set up a secondary sedimentation tank and related sludge return equipment: The in-situ nitrification-denitrification tank 19 is set up in ≥3 stages of suspended bed or fluidized bed mode. When the sewage flows through it sequentially, most of the suspended solids and microorganisms are intercepted. There is no need to set up a secondary sedimentation tank for sludge-water separation, nor is there a need for sludge return facilities.

[0098] Unlike existing activated sludge and ordinary biofilm systems, this system does not require the cultivation of activated sludge and has a short start-up time: during equipment production, a suspended carrier is already set in the in-situ nitrification-denitrification tank 19 and is already loaded with highly efficient bacteria. On-site bacterial cultivation is not required. Simply turn on the water pump and blower 21, and it can be in normal operation in just 2-3 days.

[0099] The high-density sedimentation tank 25 is designed with a double-layer anti-clogging and sedimentation-aiding structure, and also has an adsorption function. The bottom is equipped with a filter brush 31 and the top is equipped with a honeycomb inclined tube 32 to complete the two processes of contact interception and adsorption. It is equivalent to a sedimentation-contact filtration-adsorption composite tank, which is more efficient.

[0100] The septic tank has a four-stage process control to reduce the impact of rainwater on septic tank 4: the instantaneous water volume in septic tank 4 should not be too large, as excessive water volume will dilute the feces and other solid organic matter in the tank, shorten the anaerobic digestion time of solid organic matter, and reduce the treatment effect of septic tank 4; moreover, large water volume can easily carry away suspended solids, causing pipe blockage. The inlet pipe of septic tank 4 is made into the form of intercepting well 1, so that excess sewage bypasses into the grit chamber 5, avoiding the risk of sewage overflow from septic tank 4 when it is full.

[0101] The effluent quality is stable, and the requirements for operation and maintenance personnel are low: Normally, only the operation of the blower 21 and water pump needs to be ensured; no parameter adjustment is required. If phosphorus removal agent needs to be added, it can be prepared periodically. The effluent from this system can meet the Class I standard of the "Water Pollutant Discharge Standard for Centralized Rural Domestic Sewage Treatment Facilities" (DB33 / 973—2021), and the TN removal rate can reach 20%-30%.

[0102] When implementing secondary standards, the dosage of phosphorus removal agents can be reduced and the system residence time can be decreased.

[0103] Low operating costs: This process unit is equipped with 2 water pumps, 2 fans, and 1 set of phosphorus removal dosing equipment.

[0104] Electricity and labor costs are relatively low. Except for medication dispensing, everything is automated with one click, requiring only periodic inspections.

[0105] In the description of this invention, it should be noted that the terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0106] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0107] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for treating rural domestic sewage, characterized by: Includes the following steps: 1.1 Domestic sewage is collected through the pipe network and enters the intercepting well (1). During the dry season when the water volume is low, all sewage is intercepted and enters the septic tank (4) through the intercepting pipe (2). The septic tank (4) is connected to the hydrolysis regulating tank (6) by pipe. The hydrolysis regulating tank (6) is equipped with a grit chamber (5). When the water volume is large during the rainy season, sewage exceeding the capacity of the septic tank (4) enters the grit chamber (5) through the overflow pipe (3). 1.2 After the sewage in the bar screen well (5) intercepts larger floating objects and suspended solids, it flows into the hydrolysis regulating tank (6) by gravity. The hydrolysis regulating tank (6) is filled with suspended packing material (7). After the suspended packing material (7) is loaded with biofilm, its specific gravity is close to that of water. It is freely suspended in the water, making full use of the residence time of sewage in the hydrolysis regulating tank (6), so that some of the suspended solids and organic matter in the sewage can be hydrolyzed, acidified and removed in this stage. 1.3 When the sewage in the hydrolysis regulating tank (6) reaches a certain level, the lifting pump (8) is started and transported through the lifting pipeline (10). After being measured by the flow meter (11), it enters the first sludge hopper (15) of the pre-sedimentation return tank (13). The flow rate of the flow meter (11) is adjusted by the valve (12). 1.4 The pre-settling return tank (13) is equipped with sedimentation aid packing (14) and first sludge hopper (15). The upper part of the pre-settling return tank (13) is equipped with an overflow weir (18). After water collection, it flows by gravity through water passage K1 to the in-situ nitrification-denitrification tank (19). There are four groups of in-situ nitrification-denitrification tanks (19), namely 1#, 2#, 3# and 4#. The four groups of in-situ nitrification-denitrification tanks (19) are equipped with upper and lower cross-flow water passages K2, K3, K4 and K5. 1.5 The in-situ nitrification-denitrification tank (19) is equipped with biofilm suspended bed packing (20), which is a porous structure and has been modified to be hydrophilic. Each compartment of the in-situ nitrification-denitrification tank (19) is equipped with a microporous aerator (22) at the bottom, which regulates the amount of oxygen through an air regulating valve (23). The required oxygen is supplied by a blower (21). Each compartment of the in-situ nitrification-denitrification tank (19) is equipped with a vent valve (24) at the bottom, through which the aged biofilm is periodically discharged into the septic tank (4) via a sludge pipe (17). 1.6 The effluent from the in-situ nitrification-denitrification tank (19) is distributed to the upper part of the second sludge hopper (26) of the high-density sedimentation tank (25) through the water passage K5 and the water distribution pipe (27) for phosphorus removal and sludge-water separation. A mixer (28) is provided on the water distribution pipe (27), and a dosing pipe (29) is provided at the inlet of the mixer (28). A high-efficiency phosphorus removal agent is added through the phosphorus removal dosing device (30). The high-density sedimentation tank (25) is equipped with a sedimentation aid packing (14) structure, with a filter brush (31) below and a honeycomb inclined tube (32) above to complete the two processes of contact interception and adsorption. The effluent is discharged after passing through the top overflow weir (33) to meet the standards. 1.7 The sludge in the first sludge hopper (15) of the pre-settling return tank (13) is periodically transported to the septic tank (4) through the first electric valve (16) and sludge pipe (17) to form an internal circulation of hydrolysis acidification and anaerobic bacteria: The process is: pre-settling return tank (13) → septic tank (4) → hydrolysis regulating tank (6) → pre-settling return tank (13). The second sludge hopper (26) located at the bottom of the high-density sedimentation tank (25) is equipped with a second electric valve (34). Phosphorus-containing sludge is transported to the sludge tank (36) through the sludge discharge pipe (35). The supernatant of the sludge tank (36) overflows into the septic tank (4) through the sludge pipe (17). The sludge in the septic tank (4) and the sludge tank (36) is periodically pumped out or dewatered by a mobile dewatering device and then transported for disposal.

2. The rural domestic sewage treatment process according to claim 1, characterized in that: The total retention time of the in-situ nitrification-denitrification tank (19) is 10-12h, and the dosage of phosphorus removal agent is 10-15mg / L.

3. The rural domestic sewage treatment process according to claim 1, characterized in that: The total retention time of the in-situ nitrification-denitrification tank (19) is 8-10h, and the dosage of phosphorus removal agent is 5-10mg / L.

4. A rural domestic sewage treatment device, comprising the rural domestic sewage treatment process and method as described in any one of claims 1-3, characterized in that: The system includes a sewage interception well (1), with a sewage interception pipe (2) at the bottom of the sewage interception well (1) connected to a septic tank (4). The septic tank (4) is connected to a hydrolysis regulating tank (6) via a pipeline. An overflow pipe (3) is installed at the middle height of the sewage interception well (1) and connected to the hydrolysis regulating tank (6). The hydrolysis regulating tank (6) is equipped with a grid well (5). The hydrolysis regulating tank (6) is equipped with suspended packing material (7) and a lift pump (8). The lift pump (8) is connected to a pre-filled well via a pipeline (10). The pre-settling return tank (13) is connected to a pre-settling return tank (13), which is equipped with sedimentation aid packing (14) and a first sludge hopper (15). The upper part of the pre-settling return tank (13) is equipped with an overflow weir (18). The sludge in the first sludge hopper (15) of the pre-settling return tank (13) is transported to the septic tank (4) at regular intervals through a first electric valve (16) and a sludge pipe (17). The overflow weir (18) is equipped with a water passage hole K1 that allows sewage to enter the in-situ nitrification-denitrification tank (19). The in-situ nitrification-denitrification tank (19) is equipped with a biofilm suspended bed packing material (20) in the middle, and a microporous aerator (22) is provided at the bottom of the in-situ nitrification-denitrification tank (19). An vent valve (24) is also provided at the bottom of the in-situ nitrification-denitrification tank (19), through which aged biofilm is periodically discharged to the septic tank (4) via a sludge pipe (17). The effluent from the in-situ nitrification-denitrification tank (19) is distributed to the high-density sedimentation tank (25) via a water distribution pipe (27) through a water passage K5. The high-density sedimentation tank (25) is equipped with a mixer (28), a honeycomb inclined tube (32), and a filter brush (31). The top of the high-density sedimentation tank (25) is equipped with a top overflow weir (33) for discharging water. The second sludge hopper (26) at the bottom of the high-density sedimentation tank (25) is equipped with a second electric valve (34). Phosphorus-containing sludge is transported to the sludge tank (36) through the sludge discharge pipe (35). The supernatant of the sludge tank (36) overflows to the septic tank (4) through the sludge pipe (17).

5. The rural domestic sewage treatment device according to claim 4, characterized in that: The booster pump (8) is provided with a protective cover (9).

6. The rural domestic sewage treatment device according to claim 4, characterized in that: The pipeline (10) is equipped with a valve (12) and a flow meter (11).

7. The rural domestic sewage treatment device according to claim 4, characterized in that: The in-situ nitrification-denitrification tank (19) is provided with four groups, each group is provided with water passage holes. Among them, the water passage hole K2 of group 1 is located at the bottom of the in-situ nitrification-denitrification tank (19), the water passage hole K3 of group 2 is located at the top of the in-situ nitrification-denitrification tank (19), the water passage hole K4 of group 3 is located at the bottom of the in-situ nitrification-denitrification tank (19), and the water passage hole K5 of group 4 is located at the top of the in-situ nitrification-denitrification tank (19).

8. The rural domestic sewage treatment device according to claim 4, characterized in that: The microporous aerator (22) is supplied with air by a blower (21).

9. The rural domestic sewage treatment device according to claim 4, characterized in that: An air regulating valve (23) is provided in the intermediate air path of the microporous aerator (22).

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