High-efficiency three-grid septic tank treatment device based on partial nitrosation and excrement treatment method

Abstract

The invention discloses an efficient three-grid septic tank treatment device based on partial nitrosation and a feces treatment method. The treatment device comprises a stabilizing chamber, an anaerobic chamber, a partial nitrosation chamber and a settling chamber which are sequentially connected, a feeding pipeline is arranged at the upper part of the stabilizing chamber, a septic tank cover plate is arranged at a top opening, a preformed hole is formed in the septic tank cover plate, and the stabilizing chamber is communicated with the anaerobic chamber through a middle pipeline passage; a fixed polyurethane sponge filler is arranged in the anaerobic chamber, another septic tank cover plate is arranged at a top opening, and the upper part of the anaerobic chamber is communicated with the partial nitrosation chamber through a pipeline passage; another septic tank cover plate is arranged at the top of the partial nitrosation chamber, an aeration system is arranged in the septic tank cover plate, and a movable spherical filler is filled in the septic tank cover plate; the bottom of the partial nitrosation chamber is communicated with the settling chamber through a middle passage; a sediment sludge storage hopper is arranged at the bottom of the sediment chamber; a liquid outlet is formed in the upper part of the sediment chamber. The treatment efficiency and the manure utilization rate are remarkably improved, and the hydraulic retention time is shortened.

Description

Technical Field

[0001] The present invention belongs to the technical field of manure and sewage treatment, and relates to a high-efficiency three-compartment septic tank treatment device based on partial nitrification and a manure and sewage treatment method. Background Art

[0002] Existing three-compartment septic tanks are primarily used to treat toilet and kitchen wastewater, achieving initial wastewater treatment through anaerobic digestion. However, traditional three-compartment septic tanks have low treatment efficiency, typically requiring a retention time of more than 60 days to complete initial wastewater treatment, resulting in slow treatment speeds and large space requirements. Furthermore, the wastewater generated during anaerobic digestion still contains a large amount of ammonia nitrogen, resulting in unsatisfactory treatment results. When recycled as fertilizer, the high ammonia nitrogen content is not conducive to plant absorption and utilization, while also increasing the risk of environmental pollution from ammonia volatilization and nitrate leaching.

[0003] Some existing research attempts to improve wastewater treatment efficiency and effectiveness by optimizing anaerobic digestion conditions and employing aeration. For example, some success has been achieved by improving anaerobic digestion operating conditions and adding oxygen to wastewater to promote organic matter degradation and nitrogen conversion. However, due to the high water volume and low nitrogen concentration of manure and food wastewater collected at the front end, it is difficult to spontaneously sustain partial nitritation reactions, requiring complex operations and additional energy input, making it difficult to scale up in practical applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-efficiency three-compartment septic tank treatment device based on partial nitrification and a method for treating feces and sewage.

[0005] Based on high-concentration domestic wastewater collected by front-end negative pressure, this invention proposes an improved three-compartment septic tank efficient and harmless treatment method and apparatus. By introducing an aeration reaction system in the third compartment and utilizing the high ammonia and nitrogen content of the wastewater, a partial nitrosation reaction spontaneously occurs, significantly improving treatment efficiency and manure utilization, shortening hydraulic retention time, reducing the total system volume, and lowering the risk of environmental pollution. Through these improvements, the present invention not only significantly outperforms existing technologies in treatment efficiency and effectiveness, but also has high practicality and promotional value, providing a new solution for efficient and environmentally friendly wastewater treatment.

[0006] The present invention provides a high-efficiency three-compartment septic tank treatment device based on partial nitrification, comprising a stabilization chamber, an anaerobic chamber, a partial nitrification chamber and a sedimentation chamber connected in sequence; A feed pipe is provided on the upper part of the stabilization chamber, a septic tank cover is provided at the top opening, a reserved hole is provided on the septic tank cover, and the stabilization chamber is connected to the anaerobic chamber through a middle pipe passage; A fixed polyurethane sponge filler is provided in the anaerobic chamber, and another septic tank cover is provided at the top opening. The upper portion of the anaerobic chamber is connected to the partial nitrification chamber through a pipeline passage; A septic tank cover is provided on the top of the partial nitrification chamber, in which an aeration system is provided and a movable spherical filler is filled; the bottom of the partial nitrification chamber is connected to the precipitation chamber through a middle passage; A sedimentation mud storage hopper is provided at the bottom of the sedimentation chamber, and a liquid outlet is provided at the upper portion of the sedimentation chamber.

[0007] In the above-mentioned high-efficiency three-compartment septic tank treatment device based on partial nitrification, the aeration system includes an aeration pipe and an aeration plate. The top of the aeration pipe passes through the septic tank cover and the bottom is connected to the aeration plate. The front end of the aeration pipe is connected to an aeration pump. The distance between the aeration plate and the bottom of the partial nitrification chamber can be 1-5 cm, specifically 2 cm. An air outlet is also provided below the aeration plate to avoid sticking to the wall and keep a small distance from the bottom.

[0008] In the above-mentioned high-efficiency three-compartment septic tank treatment device based on partial nitrification, the feed pipe is a T-shaped pipe; The height between the bottom wall of the feed pipe and the top of the stabilization chamber may be 11-21 cm, specifically 14 cm.

[0009] In the above-mentioned high-efficiency three-compartment septic tank treatment device based on partial nitrification, the diameter of the movable spherical filler can be 20~50mm, specifically 25mm, and can be a commercially available multi-faceted hollow spherical filler made of polypropylene with a porosity of about 84%. Its main function is to form a biofilm, and it can be placed in the aeration chamber to attach aerobic microorganisms. It is a common filler in sewage treatment, and the filling volume density is recommended to be 30-60% (filler volume / aeration chamber volume).

[0010] In the above-mentioned high-efficiency three-compartment septic tank treatment device based on partial nitrification, the middle passage is provided with a partition with holes, and the aperture of the partition can be 50×10 mm; The distance between the middle passage and the bottom of the partial nitritation chamber can be 20~50cm. The effluent of the partial nitritation chamber needs to be discharged from the bottom, and the next pool is a sludge sedimentation chamber. Placing it directly at the bottom will disturb the sludge sedimentation. According to the height of the sludge plate in the sedimentation chamber, it can be specifically set to 40cm.

[0011] In the above-mentioned high-efficiency three-compartment septic tank treatment device based on partial nitrification, the number of the sedimentation sludge storage hoppers can be 2; The angle between the sedimentation sludge storage hopper and the bottom of the sedimentation chamber can be 30°.

[0012] The present invention also provides a method for treating feces and sewage using the above-mentioned high-efficiency three-compartment septic tank treatment device based on partial nitrification, comprising the following steps: 1) toilet and kitchen wastewater collected by the negative pressure system flows into the stabilization chamber through the feed pipe, undergoes solid-liquid separation and precipitation, and the generated gas is discharged through the reserved hole, and the generated plug flow liquid is discharged; 2) The push flow liquid enters the anaerobic chamber through the middle pipe passage, and an anaerobic digestion reaction occurs. The generated convection gas passes through the duct and is discharged from the reserved hole of the septic tank cover, and digestion liquid is produced; 3) the digestion liquid flows into the partial nitrification chamber through the upper pipeline to react; 4) The effluent from the partial nitritation chamber after the reaction enters the sedimentation chamber, and the aerobic suspended sludge flowing into the partial nitritation chamber is precipitated in the sedimentation sludge storage hopper, and the effluent is used as fertilizer.

[0013] The present invention has the following beneficial effects: 1. The present invention optimizes the structural design of each chamber of the three-compartment septic tank, including the layout and connection method of the stabilization chamber, anaerobic chamber, partial nitrification chamber and sedimentation chamber. For example, the feed pipe is designed to be a "T"-shaped structure to alleviate the disturbance of the feed to the stabilization chamber. Fixed fillers are added to the anaerobic chamber to improve solid-liquid separation and anaerobic efficiency. Mobile fillers and aeration systems are added to some nitrification chambers to improve liquid mixing and aerobic treatment efficiency. At the same time, combined with the pipeline connection method of each chamber, the efficiency of each treatment stage and the functionality of the system are improved as a whole.

[0014] 2. Reduced Hydraulic Retention Time: By optimizing the system design and introducing an aeration system in the third chamber to achieve partial nitrification, the hydraulic retention time of wastewater is significantly shortened, reducing the total volume of the device, improving practicality and economy. This can increase manure utilization and reduce potential environmental risks in subsequent resource utilization.

[0015] 3. Improve nitrogen resource utilization and fertilizer effect: By introducing an aeration system and optimizing the partial nitrite reaction in the reactor, ammonia nitrogen is efficiently converted into nitrite and nitrate, greatly improving the availability and fertilizer efficiency of nitrogen in manure, and solving the problems of low nitrogen conversion efficiency and poor fertilizer effect in traditional septic tanks.

[0016] 4. Shorten treatment time and reduce occupied space: By optimizing the reactor structure design and shortening the hydraulic retention time, the present invention reduces the total volume of the system, significantly shortens the wastewater treatment time, solves the problem of large space occupied by traditional three-compartment septic tanks, and is more suitable for application in areas with tight land resources.

[0017] 5. Reduce nitrogen loss and environmental risks: The optimized design of the reactor effectively controls ammonia nitrogen volatilization and nitrate leaching, reducing nitrogen loss and potential environmental pollution risks in traditional systems, and ensuring the efficiency and environmental friendliness of wastewater resource treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of the device of the present invention.

[0019] Figure 2 Schematic diagram of the process of using the device of the present invention.

[0020] The marks in the figure are as follows: 102 T-shaped feed pipe, 103 feed; 110 stabilization chamber, 111 septic tank cover, 112 ventilation duct, 113 convection gas, 114 middle pipe passage, 115 middle push flow liquid; 120 anaerobic chamber, 121 fixed polyurethane sponge filler, 122 upper pipe passage, 123 upper plug flow liquid; 130 Partial nitrification chamber, 131 Aeration tube, 132 Mobile spherical filler, 133 Aeration plate, 134 Middle passage, 135 Middle plug flow liquid; 140 sedimentation chamber, 141 sedimentation sludge storage hopper, 142 horizontal pipeline passage, 143 liquid outlet.

[0021] Figure 3 Effects of different fertilization treatments on the concentrations of chlorophyll (a), ()nitrite (b), protein (c) and polysaccharide (d) in vegetable leaves.

[0022] Figure 4 Effects of different fertilization treatments on soil pH (a), EC (b), TOC (c) and inorganic nitrogen (d) (NH4 + -N, NO2 - -N, NO3 - -N) stock and enzyme activity (e).

[0023] Figure 5 is the diversity index of soil bacterial community in different treatments.

[0024] Figure 6 This is a heat map showing the correlation between soil environmental factors and soil bacterial community composition. DETAILED DESCRIPTION

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0026] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0027] In order to better understand the content and effects of the invention, the present invention is further described through the following specific embodiments in conjunction with the accompanying drawings.

[0028] like Figure 1 As shown, the present invention provides a high-efficiency three-compartment septic tank treatment device based on partial nitrification, comprising a stabilization chamber 110, an anaerobic chamber 120, a partial nitrification chamber 130 and a precipitation chamber 140 connected in sequence; A feed pipe (a T-shaped feed pipe 102) is provided on the upper portion of the stabilization chamber 110, a septic tank cover 111 is provided at the top opening, and a reserved hole is provided on the septic tank cover 111. The stabilization chamber 110 is connected to the anaerobic chamber 120 through a middle pipe passage 114; A fixed polyurethane sponge filler 121 is provided in the anaerobic chamber 120, and another septic tank cover (not marked in the figure) is provided at the top opening. The upper portion of the anaerobic chamber 120 is connected to a portion of the nitrification chamber 130 through an upper pipe passage 122; A septic tank cover is provided on the top of the partial nitritation chamber 130 , in which an aeration system is provided and which is filled with movable spherical fillers 132 ; the bottom of the partial nitritation chamber 130 is connected to the sedimentation chamber 140 via a middle passage 134 ; A sedimentation sludge storage hopper 141 is provided at the bottom of the sedimentation chamber 140 , and a liquid outlet is provided at the top of the sedimentation chamber 140 .

[0029] Furthermore, the aeration system includes an aeration pipe 131 and an aeration plate 133. The top of the aeration pipe 131 passes through the septic tank cover, and the bottom is connected to the aeration plate 133. The front end of the aeration pipe 131 is connected to an aeration pump. The distance between the aeration plate 133 and the bottom of the partial nitrification chamber 130 is 1 to 5 cm.

[0030] Furthermore, the height between the bottom wall of the feed pipe (the T-shaped feed pipe 102 ) and the top of the stabilization chamber is 11 to 21 cm.

[0031] Furthermore, the diameter of the movable spherical filler 132 is 20-50 mm (specifically 25 mm).

[0032] Furthermore, a partition with holes is provided in the middle passage, and the aperture of the partition is 50×10 mm; The distance between the middle passage and the bottom of the partial nitrification chamber can be 20~50cm.

[0033] Furthermore, the number of the sedimentation mud storage hoppers 141 can be two; and the angle between the sedimentation mud storage hopper 141 and the bottom of the sedimentation chamber 140 can be 30°.

[0034] Example 1 The fermentation feedstock used in the experiment was obtained from a three-compartment septic tank at a test base in Henan Province. The three-compartment septic tank collects sanitary sewage from low-flushing toilets and food waste disposers. The toilet flush volume is ≤6.0 L / time and must not be mixed with washing wastewater. The combined hydraulic retention time of the first two compartments of the three-compartment septic tank is no less than 30 days.

[0035] Toilet and kitchen wastewater serves as feed 103, intermittently flowing into stabilization chamber 110 through a single T-shaped feed pipe 102. The T-shaped pipe design mitigates disturbance of the bottom material during feed, facilitating solid-liquid separation and sedimentation in the stabilization chamber compared to a traditional three-compartment septic tank. T-shaped feed pipe 102 has a diameter of 110 mm, with the bottom wall 14 cm from the top. Initial solid-liquid separation and sedimentation occur in stabilization chamber 110. Generated gases are discharged through pre-reserved holes in the septic tank cover 111. The push fluid 115 flows through central conduit 114 and then into anaerobic chamber 120 for further anaerobic digestion. The bottom wall of conduit 113 is 50 cm from the top. Anaerobic chamber 120 is filled with fixed polyurethane sponge packing 121, which effectively intercepts sludge and provides a growth zone for it. Anaerobic sludge grows on and within the packing. The anaerobic chamber 120 (with a septic tank cover but no observation port or overflow port) is provided with a ventilation duct 112 with a diameter of 25 mm at a distance of 5 cm from the top. The convective gas 113 generated in the anaerobic chamber can be discharged through the ventilation duct 112 and then through the reserved holes in the septic tank cover 111.

[0036] The digestive liquid 123 flows from top to bottom into the fully mixed partial nitritation chamber 130 through the upper conduit passage 122 (with the bottom 15 cm from the top and 5 cm from the bottom of the partial nitritation chamber 130). This prevents oxygen from flowing into the anaerobic chamber 120, thereby improving the anaerobic digestion efficiency. The partial nitritation chamber 130 is equipped with an aeration system, including an aeration pipe 131 and an aeration tray 133. It is also filled with mobile spherical biofillers 132, with the lower end of the aeration tray 133 positioned 2 cm from the bottom of the partial nitritation chamber 130. The bottom-mounted aeration tray 133 not only provides dissolved oxygen but also maximizes agitation of the liquid through rising gas, ensuring thorough and rapid mixing of the digestive liquid 123 entering from the bottom. This also drives the mobile spherical biofillers 132 to rotate, increasing the oxygen contact surface and improving aerobic treatment efficiency. The effluent 135 from the partial nitritation chamber 130 flows through the central passage 134 into the sedimentation chamber 140. The conduit passage 134 is a non-pipeline structure consisting of a square hole measuring 50 mm in length by 10 mm in width, located 40 cm from the bottom of the partial nitritation chamber 130. This hole serves to reduce liquid exchange between the partial nitritation chamber 130 and the sedimentation chamber 140, as well as the transfer of dissolved oxygen along the concentration gradient. A sedimentation sludge storage hopper 141 is located within the sedimentation chamber 140, which stores aerobic suspended sludge flowing into the partial nitritation chamber 130. During intermittent feeding, the fresh feed in the partial nitritation chamber 130 is thoroughly mixed with the existing wastewater in the chamber, which has undergone sufficient nitritation and has a dissolved oxygen concentration of 4.00-8.00 mg / L. Simultaneously, the existing and well-mixed wastewater in the partial nitritation chamber 130 is forced into the sedimentation chamber 140. The mixed wastewater contains organic matter introduced by the fresh feed. This organic matter, activated by aerobic sludge in the sedimentation sludge hopper 141, consumes the dissolved oxygen in the push fluid 135, thereby maintaining the dissolved oxygen concentration in the sedimentation chamber 140 at <1.00 mg / L. Horizontal conduit 142 removes gas, and the effluent 143 is collected for future use.

[0037] The partial nitritation chamber 130 was sampled and aerated according to the SBR operating method. The reactor's reaction parameters were as follows: intermittent aeration was provided at the bottom by a low-power air pump, with feeds occurring six times daily at 8:30, 10:30, 14:30, 16:30, 19:30, and 21:30. During the startup phase, 10 L of fermentation broth was sampled each time; during the stabilization phase, 20 L of toilet wastewater was sampled each time. At each feed time, a predetermined amount of toilet wastewater was transferred from the first chamber (stabilization chamber) of the three-chamber septic tank to the partial nitritation chamber 130. The partial nitritation chamber 130 was not pre-inoculated, and the dissolved oxygen concentration was controlled between 4.58 and 7.82°C. The temperature fluctuated between 21°C and 40°C, and the hydraulic retention time was approximately 24 hours. The partial nitritation reaction within the SBR reached a steady state after approximately 40 days.

[0038] Table 1 Inlet and outlet water quality of high-efficiency three-compartment septic tank treatment device based on partial nitrification

[0039] In Table 1, the influent is toilet and kitchen wastewater.

[0040] The results in Table 1 show that the DO levels in the stabilization chamber and partial nitrification chamber were 0.3 mg / L and 0.5 mg / L, respectively, indicating an anaerobic environment at the front end of the system, which facilitates solid-liquid separation and initial degradation of organic matter. Upon entering the partial nitrification chamber, the DO value significantly increased to 7.2 mg / L, verifying the effectiveness of the aeration system and providing a suitable environment for the activity of partial nitrosating bacteria. Upon entering the sedimentation chamber, the DO value dropped to 0.81 mg / L, indicating that oxygen was fully utilized in the partial nitrification chamber, preventing interference from dissolved oxygen on the sedimentation process. The trend in ammonia nitrogen further demonstrates the high efficiency of the partial nitrification reaction. The TAN concentration in the stabilization chamber increased from 546.5 mg / L at the inlet to 608.1 mg / L, likely due to the release of more ammonia nitrogen from the hydrolysis of organic nitrogen. In the partial nitrification chamber, TAN significantly decreased to 210.1 mg / L, achieving a removal efficiency of 65.5%, demonstrating the effective conversion of ammonia nitrogen by ammonia-oxidizing bacteria (AOB) in the system. The TAN level in the sedimentation chamber rose slightly to 221.7 mg / L, which may be due to the adsorption of some nitrogen in the sludge or incomplete conversion. The TN content of the influent was 728.2 mg / L. Under the combined action of anaerobic degradation and partial nitrite reaction, the TN of the effluent from the sedimentation chamber dropped to 501.3 mg / L, with a total removal rate of 31.2%. The removal of TN is mainly achieved through the decomposition of organic nitrogen, the oxidation of ammonia nitrogen and sludge sedimentation. At the same time, some nitrogen may be released in the form of N2 due to denitrification. In addition, the effluent from the sedimentation chamber still retains a relatively high TN content, of which NO2 - The high proportion of -N indicates that some nitritation reactions have successfully inhibited the complete oxidation of ammonia nitrogen to nitrate nitrogen, thereby increasing the fertilizer utilization value of the effluent.

[0041] The transformation of nitrogen forms showed obvious regularity in this system. The concentration of nitrite nitrogen was low at the water inlet stage, only 0.2 mg / L, and it quickly rose to 289.0 mg / L in some nitritation chambers, indicating that the AOB activity in the system was high and successfully promoted some nitritation reactions. In contrast, the concentration of nitrate nitrogen was low at the water inlet stage (0.1-1.3 mg / L), and only rose to 37.3 mg / L after some nitritation chambers, and the effluent from the sedimentation chamber dropped to 24.8 mg / L, further verifying the precise control of the nitrogen transformation pathway by this system, that is, the effective suppression of NO3 - The generation of -N reduces the environmental risk of nitrogen leaching.

[0042] The change in chemical oxygen demand reflects the system's ability to remove organic pollutants. The influent COD was as high as 2130 mg / L. During the stabilization chamber and anaerobic chamber stages, the COD dropped to 1528.0 mg / L due to the hydrolysis of organic matter and microbial degradation. After entering the partial nitrite chamber, the COD further dropped to 472.4 mg / L, and finally the effluent COD of the sedimentation chamber further dropped to 402.2 mg / L, with a removal rate of up to 81.1%. The effective removal of COD mainly depends on the degradation of anaerobic microorganisms and the aerobic degradation process promoted by the aeration system of the partial nitrite chamber. At the same time, some organic matter is removed by sludge sedimentation. This result shows that the septic tank system optimized by the present invention performs well in the degradation of organic pollutants, ensuring that the effluent has good reuse value.

[0043] In summary, the present invention optimizes the treatment effect of the three-compartment septic tank by introducing a partial nitrification process, showing significant technical advantages. First, the system successfully maintains a partial nitrification process, allowing ammonia nitrogen to be preferentially converted into nitrite nitrogen, effectively inhibiting NO3 - -N production, thereby reducing the risk of nitrate leaching. Secondly, this system significantly increased the ammonia nitrogen removal rate (65.5%), reducing the nitrogen pollution load on the environment. It also optimized the nitrogen composition of manure and improved plant utilization efficiency. Reasonable control of DO ensured an optimal growth environment for microorganisms at different stages, thereby improving the overall operating efficiency of the system.

[0044] Compared with the traditional three-compartment septic tank, the present invention has the following outstanding advantages: (1) shortening the hydraulic retention time (HRT), improving the sewage treatment efficiency, and making the system more practical; (2) reducing the generation of nitrate nitrogen, reducing the risk of eutrophication of water bodies, and ensuring that nitrogen is mainly in the form of NO2 - -N form is retained, improving the farmland utilization rate of manure; (3) optimizing the nitrogen composition of manure, the effluent after partial nitritation contains nitrogen forms that are more suitable for crop absorption, enhancing the application effect of manure; (4) reducing the sludge load, reducing the subsequent treatment costs, and improving the economy and scalability of the system.

[0045] Example 2 The planting experiment was carried out in the greenhouse of the test base on May 15, 2022, at a temperature of 30±5°C. The length, width and height of the soil box used were 40cm×30cm×40cm. The soil was taken from local sandy loam, air-dried and passed through a 1 cm sieve. The basic physical and chemical properties of the soil are shown in Table 2. A total of 7 fertilization treatments were set up, and 6 groups of repeated experiments were set up for each treatment. The treatments are shown in Table 3. Among them, the effluent from the conventional three-compartment septic tank was used as regenerated liquid fertilizer (Regenerated Liquid Fertilizer, denoted as RLF), and the effluent from the SBR reactor after stable operation in Example 1 of the present invention was used as regenerated liquid fertilizer aeration liquid (Aerated Regenerated Liquid Fertilizer, aerLF), NH4 + -N, NO3 - -N, NO2 - -N and TN treatments used ammonium chloride, sodium nitrate, sodium nitrite, and a mixture of the three in equal proportions to prepare a 200 mg / L (calculated as pure nitrogen) solution, and sodium acetate was added to maintain the same COD / TN as that of aerLF.

[0046] Table 2 Physical and chemical properties of original soil

[0047] The ability of the planting box to absorb recycled fertilizer requires a comprehensive consideration of both water and nutrients. Since the bottom of the planting box has a no-flux boundary condition, water is consumed mainly through evaporation and plant absorption, with evaporation being the main method. The FAO-56-PM-24h model was used to substitute relevant meteorological parameters of the experimental site over the years to calculate the reference crop evaporation ( ), the result is mm / d, so a single planting box can evaporate a maximum of 390.0 mL of water per day. Based on the nitrogen requirements of vegetables, approximately 280 kg / ha (as pure nitrogen) are required during the growing period (calculated as 60 days). A single planting box can absorb 0.056 g of nitrogen per day. Taking into account the average nitrogen concentrations of different fertilization treatments, the fertilizer and water volumes were determined (see Table 3). This experiment increased the frequency of fertilization and watering to reduce water and fertilizer leaching and reduced plant utilization efficiency caused by concentrated fertilization and watering. This was done to maintain consistency with the intermittent sampling method of the front-end aeration reactor. In summary, fertilization and watering were applied once daily in this experiment. After fertilization at 5:00 PM that day, water was replenished to 390.0 mL at 10:00 AM the following day.

[0048] Table 3 Fertilization and watering amounts for different treatments

[0049] In Table 3, CK represents the control group where only pure water with the same volume as the liquid fertilizer was applied. RLF and aerLF represent the treatments where recycled liquid fertilizer was applied and liquid fertilizer that had been partially nitrified in Example 1 of the present invention was applied, respectively. + -N, NO3 - -N, NO2 - -N and TN represent the treatments of single application of ammonium chloride, sodium nitrate, sodium nitrite and a mixture of the three in equal proportions, respectively.

[0050] Sampling took place on July 25, 2022, with six replicate soil and vegetable samples collected from each treatment. Soil samples were collected from the top (0–20 cm) and bottom (4–20 cm) layers of soil. Plant debris was removed, the soil was mixed, and the mixture was divided into three parts. One part was immediately tested for soil microorganisms, while the remaining soil sample was air-dried and stored at -20°C for determination of soil chemical properties and enzyme activity. Fresh plant samples were collected from aboveground soil for determination of leaf sugar, protein, chlorophyll, nitrate, and nitrite nitrogen.

[0051] TN and NO3 in recycled liquid fertilizer - -N, TAN, NO2 - Nitrogen-N and sulfonamides (SS) were determined according to standard methods. Chemical oxygen demand (COD) was measured using the reagent bottle method (COD reagent, 20–1500 mg / L, Hach, USA), while pH and dissolved oxygen were monitored using a pH / DO meter (HQ30D53000000-PHC10103 / LDO10103, Hach, USA). Vegetable biomass was measured gravimetrically. Nitrate and nitrite nitrogen in leaves were analyzed using salicylic acid nitration and sulfonamide colorimetry. Protein content in plant tissues was determined using the Folin phenol method, and soluble sugar content was determined using an anthrone colorimetric method. Soil pH was measured using a pH meter (HJ962-2018) after extraction at a water-soil ratio of 2.5:1. Electrical conductivity was measured using a conductivity meter (Cond 3310) after extraction at a water-soil ratio of 5:1. Soil organic carbon was analyzed using the potassium dichromate oxidation method combined with spectrophotometry, and total nitrogen was measured using the Kjeldahl method (HJ717-2014). Ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen were extracted with potassium chloride solution and analyzed spectrophotometrically (HJ634-2012). Soil urease activity was measured using the sodium phenol-sodium hypochlorite colorimetric method, and sucrase and cellulase activities were analyzed using the 3,5-dinitrosalicylic acid colorimetric method. Sanitary indicators were tested in accordance with GB-7959-2012. Ammonia volatilization was measured using an in situ aeration method using a homemade perforated glass box to collect nitrogen oxides (NO x ), the volatile nitrogen oxides in soil were determined by the naphthylethylenediamine hydrochloride spectrophotometric method. The effects of the partially nitrosated anaerobic regeneration liquid fertilizer prepared in Example 1 of the present invention on plant physiological characteristics are shown in the following table. Figure 3As shown in the results, the application of aerLF significantly increased the total chlorophyll content of vegetable leaves (P < 0.05), while the application of RLF significantly reduced this index. - -N inorganic fertilizer treatment group, the contents of chlorophyll a and b in leaves were significantly higher than those in other treatments, and the total chlorophyll content reached 1836.1µg / g, indicating that NO3 - -N effective absorption and conversion. The change trends of leaf polysaccharide content and total chlorophyll content were similar. When aerlf and NO3 - -N treatment significantly increased leaf polysaccharide synthesis. The leaf protein content of the aerLF treatment was 1453.1µg / g, significantly higher than that of the CK (1271.9µg / g) and RLF treatments (925.2µg / g), indicating enhanced nitrogen assimilation. In terms of nitrogen fertilizer utilization efficiency, the nitrogen fertilizer utilization efficiency of aerLF was 21.2%, significantly higher than that of the RLF treatment (10.7%). The effects of different nitrogen sources on plants showed that NO3 - -N and NH4 + -N mixed application significantly improved nitrogen utilization efficiency, NO3 - -N treatment was second. The application of aerLF can convert ammonia nitrogen into nitrite and nitrate through partial nitritation reaction, thereby improving the efficiency of nitrogen absorption and assimilation of plants.

[0052] The effects of the partially nitrosated anaerobic regenerated liquid fertilizer prepared in Example 1 of the present invention on the physical and chemical properties of the soil are shown in the following table. Figure 4 As shown: The pH of the surface and bottom soils decreased significantly after the application of RLF and aerLF (P < 0.05), and the pH value was between 8.4 and 8.6, showing a weak alkalinity. - -N and NO2 - -N reached a soil pH above 9.0, showing no significant difference from the CK (P>0.05). The EC of the upper soil layer significantly increased (163.6%) after aerLF application, while the EC of the lower soil layer was higher than that of the CK and RLF, indicating that salts were transferred from the surface to deeper soil layers after partial nitritation of the liquid fertilizer. The contribution of the inorganic nitrogen fertilizer treatment to the increase in soil EC was only half that of the organic liquid fertilizer. Soil organic carbon in the aerLF treatment was significantly higher than that of the RLF and CK (P<0.05), indicating that aerLF helps maintain soil organic carbon stocks. The aerLF treatment significantly reduced inorganic nitrogen stocks in the soil, especially ammonia nitrogen, suggesting that partial nitritation can optimize soil nitrogen forms and reduce potential environmental risks.

[0053] Table 4 Hygienic indicators of soil layers under each treatment

[0054] Effect of partial nitrite regeneration liquid fertilizer on soil harmlessness: The hygienic indicators of the surface soil and deep soil of each treatment group are shown in Table 4. The mean fecal coliform values ​​of the soil in each treatment group were much greater than 10 -4 The mortality rate of Ascaris eggs reached 100%, meeting the minimum requirement of fecal coliform bacteria value in alkaline anaerobic fermentation in the "Sanitary Requirements for Feces Harmless Treatment" (GB7959-2012). The fecal coliform bacteria value of the original soil sample was also much higher than 10 -4 The mortality rate of ascaris eggs reached 100%, and the data of the two types of indicators, namely, the regenerated liquid fertilizer and the aeration treatment, were consistent, which showed that the soil hygiene indicators of the vegetable fields after the agricultural ecosystem using the regenerated liquid fertilizer and its aeration liquid did not change significantly and all met the health and safety requirements.

[0055] Effects of partially nitrite-regenerated liquid fertilizer on soil microbial communities. Figure 5 As shown in the figure: After the application of RLF, the Ace index, Shannon index and Shannoneven index of the surface soil decreased significantly (P < 0.05), indicating that the diversity of the soil microbial community was affected and the community structure changed negatively. In contrast, the Ace and Chao1 indices of the surface soil after the application of aerLF increased significantly, indicating that partial nitrite treatment can improve the diversity and richness of the microbial community and promote the stability of soil microorganisms. Studies have shown that excessive application of nitrogen fertilizers, especially NH4 + The application of -N will reduce the species and abundance of soil microbial communities due to ammonia toxicity, changes in soil pH and increased ionic strength. The application of aerLF effectively alleviates the negative effects of ammonia toxicity and soil acidification by optimizing soil nitrogen forms, reducing ammonia nitrogen concentrations, and increasing the ratio of nitrite to nitrate, thereby promoting the recovery of microbial communities and improving their diversity. In addition, soil environmental factors such as pH, EC and organic carbon (TOC) have a significant impact on the diversity of microbial communities ( Figure 6 Studies have shown a positive correlation between pH and microbial alpha diversity, with higher soil pH contributing to greater microbial community stability and diversity. Appropriate nitrogen management not only optimizes soil nitrogen forms but also helps maintain the health and functionality of soil microbial communities.

[0056] In summary, the results show that the present invention can change the proportion of nitrogen in concentrated manure, not only significantly increasing the chlorophyll, protein and polysaccharide content of vegetable leaves, alleviating nitrate accumulation, and increasing the nitrogen fertilizer utilization rate of vegetables from 10.7% to 21.2%; it can also reduce the risk of nitrate leaching and increase the diversity of soil bacterial communities; in addition, aeration treatment can reduce the loss of gaseous nitrogen in ammonia and nitrogen oxides by 50.0%. More importantly, the average fecal coliform count of soils with long-term manure application is much greater than 10 -4The mortality rate of Ascaris eggs reached 100%, meeting the minimum requirement of fecal coliform bacteria value in alkaline anaerobic fermentation in the "Sanitary Requirements for Feces Harmless Treatment" (GB7959-2012). The fecal coliform bacteria value of the original soil sample was also much higher than 10 -4 The mortality rate of ascaris eggs reaches 100%, which meets the health and safety requirements.

Claims

1. A high-efficiency three-compartment septic tank treatment device based on partial nitrification, characterized in that: It includes a stabilization chamber, an anaerobic chamber, a partial nitrification chamber and a precipitation chamber connected in sequence; A feed pipe is provided on the upper part of the stabilization chamber, a septic tank cover is provided at the top opening, a reserved hole is provided on the septic tank cover, and the stabilization chamber is connected to the anaerobic chamber through a middle pipe passage; A fixed polyurethane sponge filler is provided in the anaerobic chamber, and another septic tank cover is provided at the top opening. The upper portion of the anaerobic chamber is connected to the partial nitrification chamber through an upper pipe passage. A septic tank cover is provided on the top of the partial nitrification chamber, in which an aeration system is provided and a movable spherical filler is filled; the bottom of the partial nitrification chamber is connected to the precipitation chamber through a middle passage; A sedimentation mud storage hopper is provided at the bottom of the sedimentation chamber, and a liquid outlet is provided at the upper portion of the sedimentation chamber.

2. The high-efficiency three-compartment septic tank treatment device based on partial nitrification according to claim 1, characterized in that: The aeration system includes an aeration pipe and an aeration plate. The top of the aeration pipe passes through the septic tank cover, the bottom is connected to the aeration plate, and the front end of the aeration pipe is connected to the aeration pump. The distance between the aeration plate and the bottom of the partial nitrification chamber is 1 to 5 cm.

3. The high-efficiency three-compartment septic tank treatment device based on partial nitrosation according to claim 1 or 2, characterized in that: The feed pipe is a T-shaped pipe; The height between the bottom wall of the feed pipe and the top of the stabilization chamber is 11-21 cm.

4. The high-efficiency three-compartment septic tank treatment device based on partial nitrosation according to claim 1 or 2, characterized in that: The diameter of the movable spherical filler is 20-50 mm.

5. The high-efficiency three-compartment septic tank treatment device based on partial nitrification according to claim 1 or 2, characterized in that: The middle passage is provided with a partition with holes, and the aperture of the partition is 50×10 mm; The distance between the middle passage and the bottom of the partial nitrification chamber is 20-50 cm.

6. The high-efficiency three-compartment septic tank treatment device based on partial nitrification according to claim 1 or 2, characterized in that: The number of the sedimentation sludge storage hoppers is 2; The angle between the sedimentation sludge storage hopper and the bottom of the sedimentation chamber is 30°.

7. A method for treating feces and sewage using the high-efficiency three-compartment septic tank treatment device based on partial nitrification according to any one of claims 1 to 6, comprising the following steps: 1) toilet and kitchen wastewater collected by a negative pressure system flows into the stabilization chamber through the feed pipe, undergoes solid-liquid separation and precipitation, and the generated gas is discharged through the reserved hole, and the generated plug flow liquid is generated; 2) The push flow liquid enters the anaerobic chamber through the middle pipe passage, and an anaerobic digestion reaction occurs. The generated convection gas passes through the duct and is discharged from the reserved hole of the septic tank cover, and digestion liquid is produced; 3) the digestion liquid flows into the partial nitrification chamber through the upper pipeline to react; 4) The effluent from the partial nitritation chamber after the reaction enters the sedimentation chamber, and the aerobic suspended sludge flowing into the partial nitritation chamber is precipitated in the sedimentation sludge storage hopper, and the effluent is used as fertilizer.

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