Method for rapid start-up of source-separated urine biological nitrification and recovery of complex nutrients

Abstract

The application discloses a method for rapid start of source-separated urine biological nitrification and recovery of composite nutrients, and belongs to the technical field of sewage treatment and resource utilization. Compared with the traditional process, the application can shorten the start-up period of the nitrification system from 98 days of the traditional process to 36 days, and shorten by 63.3%. Meanwhile, the method can make the concentration of NO2 ‑ from 147.24 mg·L ‑1 to 5.93 mg·L ‑1 , the nitrification rate from 313.87 mg N·L ‑1 ·d ‑1 to 563.70 mg N·L ‑1 ·d ‑1 , and the conversion rate of NH4 + -N to NO3 ‑ -N from 46% to 56%. In addition, the effluent obtained by the treatment has the characteristics of low nitrite and high nitrate, is rich in phosphorus, potassium, calcium, magnesium and sulfur and other nutrients necessary for plant growth, has high safety and good fertilizer efficiency, and can be used as a composite liquid fertilizer for resource utilization.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and resource utilization technology, and in particular relates to a method for rapid start-up of biological nitrification of urine separated from source and recovery of compound nutrients. Background Technology

[0002] With the continued growth of the global population, the demand for water, energy, and essential agricultural nutrients such as nitrogen, phosphorus, and potassium is constantly increasing, posing significant challenges to resource supply and sustainable development. While chemical fertilizers play a crucial role in ensuring food security, their production is highly dependent on non-renewable energy sources and is accompanied by environmental pollution. At the same time, rapid urbanization is exacerbating the pressure on wastewater treatment systems, further increasing the need for the removal and control of pollutants such as nitrogen and phosphorus. To address resource scarcity and environmental problems, recovering energy and nutrients from wastewater, especially human urine, has emerged as an innovative solution.

[0003] Urine, a significant component of urban wastewater, is rich in essential nutrients such as nitrogen, phosphorus, and potassium, which are crucial for plant growth. Although human urine accounts for only about 1% of the volume of domestic sewage, it contributes approximately 80% of the nitrogen, 56% of the phosphorus, and 63% of the potassium. The resource utilization of urine could not only alleviate the burden on wastewater treatment plants but also promote nutrient recycling and sustainable fertilizer production. Nitrogen in urine primarily exists in the form of urea, but urea is highly susceptible to hydrolysis during storage, leading to increased pH, continuous ammonia volatilization, nitrogen loss, and foul odor. Therefore, stabilizing nitrogen in urine is one of the key technical challenges in its resource utilization.

[0004] Among existing methods for urine resource recovery, biological nitrification is considered a promising approach for urine nitrogen stabilization because it almost completely retains nutrients such as nitrogen, phosphorus, and potassium, and offers advantages such as high efficiency, low operating costs, and minimal dependence on chemical reagents and energy. Under aerobic conditions, ammonia nitrogen in urine is oxidized to nitrate through nitrification, while the system pH decreases, effectively inhibiting nitrogen loss and reducing odor production.

[0005] However, the ammonia nitrogen and salinity levels in the source urine (concentrations approximately 30-50 times higher than those in domestic sewage) far exceed the tolerance limits of conventional nitrifying bacteria, making it difficult for microorganisms to adapt and easily hindering the nitrification process. Currently, a long-term, gradual salinity and ammonia nitrogen acclimatization strategy (usually exceeding 3 months) is commonly adopted, maintaining stable effluent quality by extending hydraulic retention time and increasing reactor volume. However, this method suffers from drawbacks such as long start-up cycles, high energy consumption, and large footprint, and also exhibits poor resistance to disturbances caused by fluctuations in external water quality or sudden changes in environmental conditions. Even after long-term acclimatization, nitrifying sludge remains highly sensitive to fluctuations in water quality and sudden environmental changes, easily leading to nitrite accumulation, which disrupts the balance between ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), thereby causing system instability or even collapse.

[0006] Therefore, how to overcome the technical bottlenecks of traditional methods, such as long start-up cycles, unstable water quality, and easy system collapse, and develop a urine biological nitrification process that can achieve rapid start-up and stable operation has become a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention proposes a method for rapid initiation of source-separated urine bionitrification and recovery of compound nutrients.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for rapid initiation of source-separated urine bionitrification and complex nutrient recovery, comprising the following steps: Betaine is added to the influent urine or biological nitrification reactor, and then gradually acclimatized by using 10% (volume percentage) urine, 20% urine, and 100% urine in stages, thereby achieving rapid start-up and nutrient recovery of source-separated urine biological nitrification.

[0009] Beneficial Effects: The method of this invention, by introducing betaine as a regulator into the influent urine or biological nitrification reactor, combined with a phased, gradual acclimatization strategy (urine fraction increasing sequentially from 10% to 20% to 100%), enables the biological nitrification system to rapidly start up under 100% urine conditions within 36 days. Compared to the conventional process (the conventional process mentioned herein differs from this invention in that it does not add betaine, and the process steps gradually increase from 1% urine to 100%, while other steps remain the same. The entire process takes 98 days), the start-up time is reduced by approximately 63.3%. In terms of performance, this method reduces the nitrification efficiency from 313.87 mg N·L in the conventional process. -1 ·d -1 Significantly increased to 563.70 mg N·L -1 ·d -1The conversion rate of ammonia nitrogen to nitrate nitrogen increased from 46% to 56%; the average accumulation of nitrite nitrogen during system operation in 100% urine increased from 147.24 mg / L. -1 Reduced to 5.93 mg·L -1 Furthermore, during 65 days of continuous operation, the system demonstrated excellent salt tolerance and disturbance resistance even under conditions of high-salt, high-ammonia urine water quality fluctuations, ensuring the long-term stability of the reaction process. The nitrogen in the effluent treated by this invention exists primarily in the form of ammonium nitrogen and nitrate nitrogen, while also being rich in nutrients such as phosphorus, potassium, calcium, magnesium, and sulfur, which can directly form a compound liquid fertilizer. More importantly, the fertilizer produced by this invention under betaine regulation has almost no nitrite accumulation, reducing potential phytotoxicity risks and being more beneficial to the healthy growth of crops.

[0010] In summary, this invention overcomes the technical bottlenecks of traditional urine biological nitrification processes, such as long start-up cycles, unstable operation, and easy accumulation of nitrite. It proposes a new source-separated urine treatment method that is fast, stable, and enables efficient nutrient recovery. This method is suitable for the resource utilization of urine in decentralized sanitation facilities and has good application prospects.

[0011] Optionally, the method for rapid initiation and nutrient recovery of source-separated urine biological nitrification specifically includes the following steps: (1) Collect source separated urine, add water to adjust the volume fraction to 10%, 20% and 100% urine respectively, and use it as influent urine. Add betaine to the influent urine or add it directly to the biological nitrification reactor. (2) Use activated sludge from the aeration tank of the sewage treatment plant as inoculum sludge and acclimate it under 10% urine conditions until the system is fully adapted. (3) The activated sludge was subjected to enhanced acclimatization under 20% urine conditions until the system was running stably; (4) The system was directly transitioned from 20% urine conditions to 100% urine conditions, and the stability and nitrification performance of the system were verified under these conditions; (5) Collect the effluent after treatment in step (4) and use it as compound liquid fertilizer for nutrient recovery.

[0012] Furthermore, the 10% urine sample is obtained by mixing urine and water at a volume ratio of 1:9; the 20% urine sample is obtained by mixing urine and water at a volume ratio of 1:4. The total ammonia nitrogen (TAN) in the collected urine was 689-1354 mg N·L. -1 NO3 - -N is 0.03-10.84 mg N·L -1 NO2 --N is 0.02-2.12 mg N·L -1 soluble inorganic phosphates (PO4) 3- -P) ranged from 15.5 to 48.12 mgP·L. -1 Calcium (Ca 2+ The dosage ranged from 33.2 to 116 mg / L. -1 Magnesium (Mg) 2+ The dosage ranges from 15.5 to 89 mg / L. -1 Potassium (K) + The concentration was 132-463 mg·L. -1 , sodium (Na + The concentration ranged from 356.42 to 575.84 mg / L. -1 Chloride ions (Cl) - The effective dose ranged from 416.20 to 848.24 mg·L⁻¹. -1 sulfate (SO4) 2- The dosage ranged from 77.55 to 204.60 mg / L. -1 The chemical oxygen demand (COD) is 477-1145 mg·L. -1 .

[0013] Furthermore, the inoculation concentration of activated sludge in the aeration tank of the wastewater treatment plant in step (2) is 10 ± 0.05 g / L (mass of sludge per liter of reactor).

[0014] Furthermore, in steps (2)-(4), the amount of betaine added is 150 mg / L in the influent.

[0015] Furthermore, the acclimatization time in step (2) is 8 days; the intensive acclimatization time in step (3) is 28 days.

[0016] Furthermore, the bionitrification reactor is a gravity-driven membrane bioreactor (MBR).

[0017] Furthermore, the overall operating conditions for steps (1) to (4) are as follows: the entire process is operated under aerobic conditions, with dissolved oxygen (DO) ≥ 6 mg / L and a temperature of 22 ± 1 ℃; the sludge retention time (SRT) is 50 d and the pH is 6.2 ± 0.1.

[0018] Furthermore, during the stable operation of step (4), NO2 in the effluent... - The content of -N was 5.93 mg / L, and NH4+ was... + -N to NO3 - The conversion rate of -N was 56%, and the nitration rate was 563.70 mg N·L. -1 ·d -1 .

[0019] A compound liquid fertilizer is prepared by the above method.

[0020] Optionally, the compound liquid fertilizer comprises the following elements: 7.24-38.85 mg·L⁻¹ -1 Phosphorus, 132-278 mg·L -1 Potassium, 33-98 mg·L -1 Calcium, 11.7-73 mg·L -1 Magnesium and 75-206 mg·L -1 sulfur.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects: (1) Fast system start-up speed: Traditional urine biological nitrification process requires a start-up period of about 98 days. The main reason is that under high salt and high ammonia conditions, the microbial community adapts slowly and is prone to NO2. - -N accumulation delays system stabilization. This invention, by introducing betaine as a regulator and combining it with a gradual concentration acclimation strategy, achieves rapid start-up of the nitrification system in 36 days, shortening the start-up time by approximately 63% compared to traditional processes, and significantly improving the feasibility of engineering applications.

[0022] (2) Enhanced system operational stability: Under high-salt and high-ammonia conditions, traditional nitrification systems are prone to nitrification interruption or nitrite accumulation due to inhibited microbial activity, thus affecting system stability. Under the conditions of this invention, NO2 levels are significantly reduced during operation in 100% urine. - -N accumulation was 5.93 mg·L⁻¹. -1 It is significantly lower than 147.24 mg·L under traditional process conditions. -1 The accumulation level indicates that betaine helps enhance the system's tolerance and resistance to disturbances in high-salt and high-ammonia environments, providing a guarantee for applications under decentralized and unstable load conditions.

[0023] (3) The nitrification rate is significantly improved: the nitrification rate of the traditional process under 100% urine conditions is 313.87 mgN·L. -1 ·d -1 Furthermore, the rate decreased when the urine proportion exceeded 50%, reflecting the inhibitory effect of the high-salt, high-ammonia environment of urine on the nitrification process. This invention achieved 563.70 mg N·L under the same conditions. -1 ·d -1 The nitration rate is approximately 1.80 times that of the conventional process, indicating that the present invention can effectively improve the nitration capacity of the system.

[0024] (4) NH4 + -N to NO3 --N conversion rate improved: Under 100% urine conditions, the traditional process... + -N to NO3 - The conversion rate of nitrogen (N-N) was only 46%. This invention can increase this conversion rate to 56% under the same conditions. The increased proportion of nitrate in the effluent helps improve the stability of the product's form, thus achieving efficient and stable recovery of nitrogen from urine.

[0025] (5) Improved stability and safety of the product fertilizer: The nitrogen in the effluent after treatment by this invention is mainly in the form of ammonium nitrogen and nitrate nitrogen, and also contains nutrients such as potassium, calcium, magnesium, and phosphate, which can form a compound liquid fertilizer. Compared with the traditional process, the accumulation of nitrite in the effluent under the conditions of this invention is significantly reduced, thereby reducing the potential risk of plant toxicity, improving the safety of the fertilizer and the nutrient recovery efficiency, and facilitating large-scale promotion and application. Attached Figure Description

[0026] The accompanying drawings, which constitute a 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 undue limitation of the invention. In the drawings: Figure 1 The traditional process of gradual domestication and the addition of betaine in Example 1 of this invention were compared, with the influent and effluent NH4+ during the nitrification start-up process at urine proportions of 10%, 20%, and 100%. + -N concentration, NO3 in effluent - -N concentration, NO2 in effluent - -N concentration and NH4 + -N to NO3 - -N conversion rate change curve.

[0027] Figure 2 The graph shows the changes in nitrification rate under different urine ratios for each stage of the traditional process and the process of adding betaine in Example 1 of this invention.

[0028] Figure 3 A comparison chart showing the composition of water-fertilizer obtained under 100% urine conditions using the traditional process and the process of adding betaine in Example 1 of this invention.

[0029] Figure 4 This is a comparison chart showing the effects of liquid fertilizer obtained by the traditional process and the process of adding betaine in Example 1 of this invention on plant fertilization. Detailed Implementation

[0030] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] This invention introduces betaine into the bionitrification process of urine source separation, and combined with a gradual acclimatization strategy, achieves rapid start-up and stable operation of the urine bionitrification system. This method effectively overcomes the limitations of traditional processes, such as long start-up cycles and poor system stability, providing a new technical approach for efficient urine treatment and nutrient recovery.

[0036] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for rapid initiation of source-separated urine bionitrification and complex nutrient recovery, comprising the following steps: (1) Determination of betaine dosage The dosage of betaine was determined to be 150 mg / L in the influent. Betaine can be added to the reactor along with the influent urine, or directly to the reactor based on the amount of influent urine. Betaine must be added in steps (2), (3), and (4).

[0037] (2) Initial acclimatization and enrichment (10% urine concentration) Activated sludge from the aeration tank of a municipal wastewater treatment plant was used as inoculum sludge. Collected urine was mixed with tap water at a volume ratio of 1:9 (i.e., urine content was 10%) for sludge enrichment and initial acclimation. When the reactor effluent NO3... - -N concentration gradually increased and approached that of influent NH4. + -N concentration 50%, and no NO2 was observed. - When -N accumulates, the sludge adaptation is considered complete. This stage takes 8 days.

[0038] (3) Intensive training (20% urine concentration) Based on the activated sludge system acclimated in step (2) above, the collected urine and tap water were mixed at a volume ratio of 1:4 (urine ratio of 20%) to further acclimatize and enrich the activated sludge. When the system's NO3... - -N content gradually increases and then stabilizes, with no NO2 present. - The significant accumulation of -N indicates that the intensive training is complete. This stage lasts 28 days.

[0039] (4) Start-up and stability verification under high concentration urine (100% urine) After acclimatization with 20% urine, the reactor was directly transitioned to operation under 100% source-separated urine conditions. During operation, the system effluent NO3... - -N concentration was stable, and NO2 was not observed. - -N accumulation indicates that urinary biological nitrification has been initiated. Compared to the traditional process with a start-up cycle of approximately 98 days, this invention requires only 36 days, significantly shortening the start-up time. Furthermore, even after 65 days of operation under fluctuating influent water quality conditions, the system effluent NO3... - -N concentration remained stable, with almost no NO2 present. - The accumulation of -N indicates that the nitration system with added betaine has strong stability.

[0040] (5) Plant irrigation application: After step (4), the effluent from the MBR reactor was collected and diluted five times as irrigation water, with tap water as a control. Irrigation was carried out every 3 days, with 150 mL of the corresponding treatment solution applied each time. The experiment lasted for 30 days, and plant photos were taken every 10 days to monitor plant growth.

[0041] The urine used in steps (2), (3), and (4) above is from completely hydrolyzed male toilet flush urine, and its main water quality characteristics are as follows: total ammonia nitrogen (TAN) is 689-1354 mg N·L. -1 NO3 - -N is 0.03-10.84 mg N·L -1 NO2 --N is 0.02-2.12 mg N·L -1 soluble inorganic phosphates (PO4) 3- -P) ranged from 15.5 to 48.12 mgP·L. -1 Calcium (Ca 2+ The dosage ranged from 33.2 to 116 mg / L. -1 Magnesium (Mg) 2+ The dosage ranges from 15.5 to 89 mg / L. -1 Potassium (K) + The concentration was 132-463 mg·L. -1 , sodium (Na + The concentration ranged from 356.42 to 575.84 mg / L. -1 The chloride ion (Cl⁻) concentration ranged from 416.20 to 848.24 mg·L⁻¹. -1 sulfate (SO4) 2- The dosage ranged from 77.55 to 204.60 mg / L. -1 The chemical oxygen demand (COD) is 477-1145 mg·L. -1 .

[0042] In some optional embodiments, steps (2), (3), and (4) are all carried out in a gravity-driven membrane bioreactor, with the sludge concentration controlled at 10 ± 0.05 g / L. The entire process is operated under aerobic conditions, with dissolved oxygen (DO) ≥ 6 mg / L and a temperature of 22 ± 1 ℃; the sludge retention time (SRT) is set to 50 d. The pH value is adjusted in real time via an automatic monitoring system, with a set value of 6.2 ± 0.1. When ammonia oxidation consumes alkalinity, causing a decrease in pH, the system automatically adds fully hydrolyzed urine via a dosing pump to replenish alkalinity and maintain optimal reaction conditions.

[0043] In some optional embodiments, in steps (2), (3), and (4), reactor effluent samples are collected every two days to determine NH4. + -N, NO3 - -N and NO2 - -N concentration is used to evaluate the biological nitrification performance and operational stability of the system; In addition, at the end of step (4), NH4 in the water was further detected. + -N, NO3 - -N, NO2 - -N、K + Ca 2+ Mg 2+ Na + PO4 3- -P, Cl -Indicators such as COD were used to evaluate the composition characteristics and application performance of the resulting nutrient solution fertilizer.

[0044] All pharmaceutical agents used in this invention were purchased from the market.

[0045] The technical solution of the present invention will be further described below with reference to the embodiments.

[0046] Example 1 A method for rapid initiation of bionitrification and complex nutrient recovery in source-separated urine includes the following steps: Sludge source: The activated sludge comes from the aeration tank of a municipal wastewater treatment plant in North China.

[0047] Urine source: Male toilet flush urine, completely hydrolyzed. Key water quality characteristics are as follows: Total ammonia nitrogen (TAN) 689-1354 mg N·L -1 NO3 - -N 0.03-10.84 mg N·L -1 NO2 - -N 0.02-2.12 mg N·L -1 soluble inorganic phosphates (PO4) 3- -P) 15.5-48.12 mg P·L -1 Calcium (Ca 2+ 33.2-116 mg·L -1 Magnesium (Mg) 2+ 15.5-89 mg·L -1 Potassium (K) + 132-463 mg·L -1 , sodium (Na + 356.42-575.84 mg·L -1 Chloride ions (Cl⁻) 416.20-848.24 mg·L⁻¹ -1 sulfate (SO4) 2- 77.55-204.60 mg·L -1 Chemical oxygen demand (COD) 477-1145 mg·L -1 .

[0048] In this embodiment, betaine is used as a regulator, with an addition concentration of 150 mg / L influent. It can be added to the reactor along with the influent urine, or added directly according to the influent volume.

[0049] Reactor operating conditions: The reactor is a gravity-driven membrane bioreactor (MBR). Sludge concentration is controlled at 10 ± 0.05 g / L. It operates entirely aerobically, with dissolved oxygen (DO) ≥ 6 mg / L. Temperature control: 22 ± 1 ℃. Sludge retention time (SRT): 50 d. pH is automatically adjusted in real-time via a monitoring system, with a setpoint of 6.2 ± 0.1; when ammonia oxidation depletes alkalinity, causing a pH decrease, the system replenishes alkalinity by adding fully hydrolyzed urine via a dosing pump.

[0050] Collected urine was mixed with tap water at volume ratios of 1:9 and 1:4 to prepare 10% and 20% urine solutions, respectively. The raw urine collected directly was used as 100% urine. Urine solutions of different concentrations were sequentially introduced into the urine equalization tank according to the system's operation schedule. Throughout the entire operation, betaine (150 mg / L) was added to the influent. The inoculated sludge was then connected to the MBR for enrichment, acclimation, and stability verification. During operation, effluent samples were collected every two days to measure NH4. + -N, NO3 - -N and NO2 - -N concentration, based on influent and effluent NH4 + The nitrification rate was calculated based on the N-N concentration, the volume of urine consumed, and the time taken for urine consumption. After the 100% source-separated urine test, NH4+ in the water was further detected. + -N, NO3 - -N, NO2 - -N、K + Ca 2+ Mg 2+ Na + PO4 3- -P, Cl - Indicators such as COD are used to evaluate the stability and safety of fertilizers.

[0051] Figure 1 The gradual acclimatization process of traditional technology (without betaine) and the nitrification start-up process of Example 1 of this invention with added betaine, including the influent and effluent NH4 content. + -N concentration, NO3 in effluent - -N concentration, NO2 in effluent - -N concentration and NH4 + -N to NO3 - -N conversion rate change curve. From Figure 1 It can be seen that under 10% urine conditions, NO3... - -N concentration gradually increased and NO2 was not observed. - Accumulation, NH4 + -N to NO3 -The conversion rate of -N increased to 48%, indicating that initial acclimatization was complete, taking approximately 8 days. Subsequently, the urine concentration was increased to 20%, and the effluent NO3... - -N concentration gradually increased and tended to stabilize, and no NO2 was observed. - -N accumulation indicates successful acclimatization, taking approximately 28 days. After a 36-day adaptation period with low-concentration urine and betaine, the system successfully transitioned directly from 20% urine to 100% urine conditions. The system then operated continuously for 65 days under fluctuating 100% urine water quality conditions, with effluent NO3 levels... - The average concentration of -N reached 504.98 mg·L⁻¹. -1 There is virtually no NO2. - The accumulation of NH4 indicates that the system has achieved rapid startup and possesses high tolerance and disturbance resistance. + -N to NO3 - The -N conversion rate remained stable at 56%, significantly higher than the 46% of the traditional process. This indicates that the addition of betaine effectively enabled rapid initiation of urine nitrification within 36 days, shortening the time by approximately 63.3% compared to the traditional process (98 days without betaine), while simultaneously increasing NH4+ conversion. + -N to NO3 - -N conversion rate and significantly reduced NO2 - Accumulation has enhanced the stability of the system.

[0052] Figure 2 The graph shows the changes in nitrification rate under different urine ratios for each stage of the traditional process's gradual acclimatization and the process of adding betaine in Example 1 of this invention. The nitrification rate of the traditional process under 100% urine conditions is 313.87 mg N·L. -1 ·d -1 Furthermore, the nitrification rate decreased after the urine proportion exceeded 50%, indicating the inhibitory effect of the high-salt, high-ammonia environment of urine and intermediate products on the nitrification process. In contrast, the nitrification rate of the process described in this invention reached 563.70 mg N·L under the same conditions. -1 ·d -1 It is approximately 1.80 times that of traditional methods.

[0053] Figure 3 To compare the composition of the water-soluble fertilizer obtained under 100% urine conditions using the traditional process and the betaine-adding process of Example 1 of this invention, including NH4+... + -N, NO3 - -N, NO2 - -N、K + Ca 2+ Mg 2+ Na + PO4 3- -P, Cl - and SO42- As shown in the figure, the nitrogen in the effluent treated by the process of this invention mainly exists in the form of ammonium nitrogen and nitrate nitrogen. It also contains nutrients necessary for plant growth such as phosphorus, potassium, calcium, magnesium, and sulfur, with concentrations of 7.24-38.85, 132-278, 33-98, 11.7-73, and 75-206 mg·L⁻¹, respectively. -1 This resulted in a compound liquid fertilizer.

[0054] Example 2 After completing the operation under 100% source-separated urine conditions in Example 1, effluent was collected from the MBR reactor and diluted five times for irrigation, with tap water used as a control. Healthy, disease-free plant seeds were selected for hydroponic cultivation for the irrigation experiment. All plants were planted in containers of equal volume and cultivated under identical environmental conditions. Irrigation was performed every 3 days during the experiment, with 150 mL of the corresponding treatment solution applied each time. Cultivation continued for 30 days, and photographs were taken every 10 days to monitor plant growth and evaluate the effects of different irrigation treatments on plant growth.

[0055] Figure 4 This figure compares the effects of liquid fertilizer obtained through conventional processes with the liquid fertilizer obtained through the process of adding betaine in Example 1 of this invention on plant fertilization. As can be seen from the figure, compared with the plain water control group, plants irrigated with bio-nitrified urine fertilizer (both conventional processes and those with added betaine) showed significant growth advantages, indicating that urine treated by bio-nitrification has the feasibility of being utilized as a liquid fertilizer. Furthermore, compared with fertilizer obtained through conventional processes, the fertilizer obtained through the process of adding betaine in Example 1 showed higher fertilizer efficiency and application potential due to a significant reduction in nitrite accumulation in the effluent, thus lowering the potential toxicity risk to plants.

[0056] A method for gradual domestication using traditional techniques differs from Embodiment 1 of this invention in that betaine is not added, and the process involves gradually increasing the concentration of urine from 1% to 100%. The entire process takes 98 days.

[0057] The specific differences between the preparation process of Example 1 of this invention and the traditional process are shown in Table 1: Table 1 In addition, the present invention has conducted the following comparative experiments to demonstrate the synergistic effect of the raw materials and processes used in the present invention.

[0058] Comparative Example 1: The comparative example has the same source of inoculated sludge, urine water quality and basic operating conditions of the reactor as Example 1. The difference is that trehalose is used as a regulator in this comparative example, with a concentration of 350 mg / L influent, to replace betaine in Example 1.

[0059] Operating steps: Urine from flushing was mixed with tap water at volume ratios of 1:9 and 1:4 to prepare 10% and 20% urine solutions, respectively. The raw urine collected directly was used as the 100% urine solution, and these solutions were sequentially introduced into the urine conditioning tank according to the operational schedule. Throughout the entire operation, trehalose at a concentration of 350 mg / L was continuously added to the influent. Effluent samples were collected every two days to test for NH4. + -N, NO3 - -N, NO2 - -N, and calculate the nitrification rate using the same method as in Example 1; after the system enters the 100% urine stabilization stage, further test the fertilizer components and COD in the effluent to evaluate stability and safety.

[0060] Execution result: 1) Start-up and Phase Transition: In the 10% urine phase, the system NO3 - -N gradually increases, NH4 + -N to NO3 - -N conversion rate increased to 52.60%, NO2 - -N accumulates slightly; after 16 days of operation, it increases to 20% in urine, and the system can still maintain a low NO2 level. - -N level. After approximately 40 days of acclimatization with low-concentration urine and trehalose, the system can transition directly from 20% urine to 100% urine and enter stable operation.

[0061] 2) Stable operation characteristics with 100% urine: NO3 in the effluent during the 100% urine stage - -N is approximately 494.00 mg / L, and the effluent NH4 content is... + -N is approximately 406.03 mg / L; but NO2 - -N still accumulates under fluctuating conditions, averaging NO2 - -N was approximately 18.75 mg / L, and the nitration conversion rate remained stable at 51.05%.

[0062] 3) Nitrification rate: Under 100% urine conditions, the nitrification rate is approximately 388.96 mg N·L. -1 ·d -1 Furthermore, the fluctuation range is relatively large (high dispersion), indicating that the process stability is still affected by high salt and high ammonia fluctuations.

[0063] Comparison and explanation: Under the same reactor and operating conditions, a higher dosage of trehalose (350 mg / L) is required to achieve the transition from 20% urine to 100% urine; its NO2 content in the 100% urine stage is higher. - The average N-N concentration remained at 18.75 mg / L, the conversion rate at 51.05%, and the nitrification rate at 388.96 mg N·L. -1 ·d -1 In contrast, in Example 1, only 150 mg / L of betaine was needed to achieve lower NO2 levels in 100% urine. - -N (5.93 mg / L), higher and more stable conversion (56%), and higher nitrification rate (563.70 mgN·L). -1 ·d -1 It exhibits stronger resistance to water quality fluctuations and long-term stability.

[0064] Comparative Example 2: The comparative example has the same source of inoculated sludge, urine water quality and basic operating conditions of the reactor as Example 1. The difference is that glutamic acid is used as a regulator in this comparative example, with a concentration of 300 mg / L influent, to replace betaine in Example 1.

[0065] Operating steps: The flushing urine was mixed with tap water at volume ratios of 1:9 and 1:4 to prepare 10% and 20% urine solutions, respectively. The raw urine collected directly was used as 100% urine solution and was sequentially introduced into the urine conditioning tank according to the operation progress. Throughout the operation, glutamic acid at 300 mg / L was continuously added to the influent; effluent samples were collected every two days to test for NH4. + -N, NO3 - -N, NO2 - -N, and calculate the nitrification rate using the same method as in Example 1; after the system enters the 100% urine stabilization stage, further test the fertilizer components and COD in the effluent to evaluate stability and safety.

[0066] Execution result: 1) Start-up and Phase Transition: Nitrification is gradually established in the 10% urine stage, NH4+ + -N to NO3 - -N conversion rate can reach approximately 50.1% and NO2 - -N accumulation was low; NO2 remained low after increasing to 20% of urine on day 12. - -N level. After approximately 32 days of acclimatization with low-concentration urine and glutamate, it can directly transition from 20% urine to 100% urine.

[0067] 2) Stable operation characteristics with 100% urine: NO3 in the effluent during the 100% urine stage --N is approximately 508.39 mg / L, and the effluent NH4 content is... + -N approximately 418.91 mg / L; NO2 - -N averaged approximately 14.73 mg / L, with a stable nitration conversion rate of 52.04%.

[0068] 3) Nitrification rate: Under 100% urine conditions, the nitrification rate is approximately 416.35 mg N·L. -1 ·d -1 It also exhibits significant fluctuations (large dispersion).

[0069] Comparison and explanation: A dosage of 300 mg / L of glutamate is required to achieve a rapid transition to 100% urine operation. Although the start-up time is relatively short (approximately 32 days), its NO2 content is significantly reduced during the 100% urine stability phase. - The average N-N concentration remained at 14.73 mg / L, the conversion rate was 52.04%, and the nitrification rate was 416.35 mg N·L. -1 ·d -1 In contrast, in Example 1, only 150 mg / L of betaine was needed to reduce NO2 in 100% urine. - -N was further reduced to 5.93 mg / L, and the nitrate conversion rate was increased and stabilized at 56%, while the nitrification rate was increased to 563.70 mg N·L. -1 ·d -1 This demonstrates lower dosage and stronger NO2. - It offers a combination of advantages, including strong inhibition capabilities, higher nitrification rates, and superior stability against disturbances.

[0070] Comprehensive comparison: Under the same sludge source, urine source, and reactor operating conditions, all three osmotic protectants could promote the system's transition from low-concentration urine to 100% urine and maintain operation; however, differences in dosage and NO2... - A comprehensive evaluation of control, conversion rate and nitrification rate, and stability against water quality fluctuations showed that betaine performed best. Lower dosages: betaine 150 mg / L < glutamate 300 mg / L < trehalose 350 mg / L; 100% urine stage NO2 - Lower: Betaine 5.93 mg / L < Glutamic acid 14.73 mg / L < Trehalose 18.75 mg / L; Higher and more stable nitration conversion rates: Betaine 56% > Glutamic acid 52.04% > Trehalose 51.05% > Traditional process 46%; The highest nitrification rate was observed in 100% urine sample: betaine 563.70 > glutamate 416.35 > trehalose 388.96 > conventional process 313.87 mg N·L -1 ·d -1 .

[0071] Therefore, under the conditions of this invention and its operation, betaine achieves a higher nitrification rate and lower NO2 with a lower dosage. - It accumulates and maintains greater stability against the backdrop of fluctuating urine water quality, making it suitable as an osmotic protectant for the urine nitrification process.

[0072] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for rapid initiation of bionitrification and complex nutrient recovery from source-separated urine, characterized in that, Includes the following steps: Betaine is added to the influent urine or biological nitrification reactor, and the urine from the source is biologically nitrified by gradually increasing the concentration of urine to 10%, 20%, and 100%. The treated effluent is then collected as a compound liquid fertilizer.

2. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 1, characterized in that, Specifically, the following steps are included: (1) Collect source separated urine, add water to adjust the urine to volume fractions of 10%, 20% and 100% respectively, and use it as influent urine. At the same time, add betaine to the influent urine or add it directly to the biological nitrification reactor. (2) Use activated sludge from the aeration tank of the sewage treatment plant as inoculum sludge and acclimate it under 10% urine conditions until the system is fully adapted. (3) The activated sludge was subjected to enhanced acclimatization under 20% urine conditions until the system was running stably; (4) Switch the system directly from 20% urine operating conditions to 100% source-separated urine operating conditions; (5) Collect the treated effluent and use it as a compound liquid fertilizer for nutrient recovery.

3. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 2, characterized in that, The 10% urine was obtained by mixing source-separated urine with water at a volume ratio of 1:9; the 20% urine was obtained by mixing source-separated urine with water at a volume ratio of 1:

4.

4. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 2, characterized in that, The concentration of the inoculated sludge in step (2) is 10 ± 0.05 g / L.

5. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 2, characterized in that, In steps (2) to (4), the amount of betaine added is 150 mg / L of influent.

6. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 2, characterized in that, The acclimatization time in step (2) is 8 days; the intensive acclimatization time in step (3) is 28 days.

7. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 2, characterized in that, The overall operating conditions for steps (1) to (4) are: the entire process is carried out under aerobic conditions, with dissolved oxygen ≥6mg / L and temperature of 22 ± 1℃; The sludge retention time was 50 days, and the pH was 6.2 ± 0.

1.

8. The method for rapid initiation of source separation urine bionitrification and complex nutrient recovery according to claim 2, characterized in that, During the stable operation of step (4), NO2 in the effluent... - The content of -N was 5.93 mg / L, and NH4+ was... + -N to NO3 - The conversion rate of -N was 56%, and the nitration rate was 563.70 mg N·L. -1 ·d -1 .

9. A compound liquid fertilizer, characterized in that, Prepared by the method described in any one of claims 1-8.

10. A compound liquid fertilizer according to claim 9, characterized in that, The nitrogen in the compound liquid fertilizer mainly exists in the form of ammonium nitrogen and nitrate nitrogen, and also includes the following elements: 7.24-38.85 mg·L. -1 Phosphorus, 132-278 mg·L -1 Potassium, 33-98 mg·L -1 Calcium, 11.7-73 mg·L -1 Magnesium and 75-206 mg·L -1 sulfur.

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