Device and method for quickly starting shortcut nitrification process

Abstract

The invention discloses a device and method for quickly starting a short-cut nitrification process and belongs to the field of water treatment. The method comprises the following steps: inoculating sludge in a secondary sedimentation tank into a sequencing batch device, adding a polyurethane biological sponge carrier, firstly adopting a strategy of sectional water inlet and post-aeration progressive increase (increasing duration first and then increasing aeration quantity), driving Candidate Condenser to migrate to the sponge carrier by utilizing nitrate and a dynamic oxygen environment, and completing enrichment domestication; the obstruction of the O2 on the endogenous denitrification process of the Candidate Condenter in an aerobic environment is reduced; the short-cut nitrification method is characterized in that a sectional water inlet measure is canceled, NH4 < + >-N synthetic wastewater is introduced, a strategy of low alkalinity (reduction of KHCO3 concentration of inlet water) and first increase and then decrease (aeration rate) of post-aeration is adopted, growth of NOB is hindered in combination with strong NO2 <->-N reduction capability of Candidate Condenter in a low dissolved oxygen environment, and rapid start of a short-cut nitrification process is completed.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a device and method for rapidly starting a shortcut nitrification process. Background Art

[0002] Due to the high energy consumption and carbon emission limitations of traditional biological sewage treatment processes, in order to improve the sustainability of urban wastewater treatment plants (WWTPs), scholars at home and abroad have continuously explored new sewage treatment methods. Compared with the complete nitrification process (NH4 + -N → NO3 - -N), shortcut nitrification (PN) (NH4 + -N → NO2 - -N) has advantages such as low aeration energy consumption and easy coupling with other processes. Therefore, coupling denitrification processes such as shortcut nitrification / denitrification, shortcut nitrification / anaerobic ammonium oxidation, and simultaneous shortcut nitrification and denitrification have emerged. These new processes basically improve the denitrification efficiency on the basis of reducing energy consumption. Among them, as the front-end process of the above processes, the rapid start-up and stability of PN are the prerequisites for the efficient denitrification of the coupling system.

[0003] To achieve a stable PN process, it is required to enhance the activity of ammonia-oxidizing bacteria (AOB) and stably inhibit or remove nitrite-oxidizing bacteria (NOB), so as to achieve AOB enrichment. Therefore, rapidly starting PN means washing out NOB from the system in a short time while effectively retaining AOB in the system. It is known that in the environment of low ammonia nitrogen concentration (40 - 80 mg / L) in domestic sewage, the ammonia nitrogen substrate available for AOB is less and NOB has a higher affinity for the substrate and oxygen. Therefore, how to rapidly start the PN process has become a key research direction. In recent years, some factors related to the start-up of PN have been discovered, including temperature, dissolved oxygen, pH value, free nitrous acid, and sludge age. Comprehensive optimization of various influencing factors is the key to starting shortcut nitrification. It has also been found that the start-up process of shortcut nitrification can be accelerated by optimizing the aeration method, applying an external magnetic field, applying an external ultrasonic wave, or adding chemical reagents. However, it is challenging to meet some conditions in the actual application scenario and the required cost is high, making it difficult to achieve. In addition, hydroxylamine is often used to promote the start-up of the PN process, but the input of a large amount of chemical reagents may cause irreversible damage to other functional bacteria in the system, and long-term dosing will additionally increase the operating cost. To sum up, there is an urgent need to develop a new, effective, low-cost, and non-biologically toxic PN start-up method.

[0004] Controlling the NH4 + -N oxidation reaction at the NO2 - -N stage and not being further oxidized by NOB to NO3 --N is the key and goal for starting PN. Previous studies have focused on the metabolic or survival condition differences between AOB and NOB, and have not addressed the competition between the two from the perspective of biological assistance. For example, using the denitrification process to directly reduce NO2 - -N to N2 without further oxidation. This may be attributed to the fact that external organic matter tends to be oxidized in an aerobic environment rather than being supplied to ordinary heterotrophic denitrifying bacteria for denitrification. Therefore, enhancing the denitrification of denitrifying bacteria in the aerobic stage has become the breakthrough point for solving the technical difficulties of this technology. In recent years, the endogenous denitrification process carried out by denitrifying glycan-accumulating organisms has attracted much attention. It converts external organic matter into intracellular carbon source polyhydroxyalkanoates (PHA) in an anaerobic environment, which can effectively reduce the waste of carbon source in the aerobic zone. It is known that Candidatus Contendobacter has excellent NO2 - -N reduction performance in the dominant environment. Based on this, this study aims at the difficulty of slow start-up speed of the PN process and develops a device and method for quickly starting the shortcut nitrification process, which is of great significance for promoting the practical application of the PN process and realizing sustainable development. Summary of the Invention

[0005] What this invention solves is the technical problem of how to quickly start the PN process, and further provides a device and method for quickly starting the shortcut nitrification process. This invention also provides a quick start device for realizing this method.

[0006] The technical solution adopted by this invention to solve the above technical problems is as follows:

[0007] A method for quickly starting the shortcut nitrification process, including: (1) inoculating secondary sedimentation tank sludge into the sequencing batch device and adding polyurethane biological sponge carriers. Before the start of each cycle operation, a carbon source medium is introduced. The system operation cycle duration is set to 6 - 8 hours. When stirring runs to 1 / 4 of the reaction cycle duration, a nitrate concentrate is introduced, and the NO3 - -N concentration in the device after the introduction of the nitrate concentrate is controlled to be 40 - 80 mg / L. By adjusting the COD concentration of the carbon source medium (COD is supplied by CH3COONa) within the range of C / N ratio (COD / NO3 - -N) of 2.7 - 3.0, the system is regulated to run until the total nitrogen (NO3 - -N and NO2 -The removal rate of -N is higher than 95%. After that, a strategy of increasing post-aeration incrementally (first increasing the duration and then the aeration volume) is adopted. Aeration starts after the nitrate concentrate is introduced. Initially, the dissolved oxygen (DO) concentration in the system is controlled at 0.1 mg / L, the aeration duration is 1 h, and the remaining reaction cycle duration continues to operate in an anoxic state. Based on the condition that the total nitrogen removal rate of the system is higher than 95%, only the aeration duration is increased. Taking the cycle as a unit, it is increased by 0.5 h each time. When the total nitrogen removal rate is lower than 95% as the critical point, the increase in aeration duration stops. After the aeration duration is determined, taking the cycle as a unit, the aeration volume is increased step by step, and the DO in the corresponding device is increased by 0.5 mg / L each time. When the DO is 1 - 2 mg / L and the total nitrogen removal rate is lower than 90% as the critical point, and the high-throughput data results show that Candidatus Contendobacter is the microbial genus with the highest abundance in the system, the pre-cultivation of Candidatus Contendobacter ends. Measure the COD concentration in the influent water of the last cycle of this step, the NO3 - -N concentration in the device after the nitrate concentrate is introduced, and the DO concentration during aeration, which are used to determine the influent COD, NH4 + -N concentration and the aeration volume during aeration in the subsequent steps. (2) Based on the Candidatus Contendobacter sludge, biological carrier obtained in step (1), and the determined cycle and aeration duration, start the shortcut nitrification process. Specifically: Before the device starts to operate, synthetic wastewater is introduced, and stirring is carried out until aeration starts when it reaches 1 / 4 of the reaction cycle duration. First, the aeration volume is increased once to maintain the DO concentration in the device consistent with the DO concentration measured in the last cycle of step (1). Under this condition, when there is no NH4 + -N remaining in the effluent and the NO3 - -N concentration is higher than 5 mg / L, taking the cycle as a unit, the aeration volume is decreased step by step, and the change in DO concentration each time does not exceed 0.2 mg / L until there is no NH4 + -N and NO3 - -N remaining in the effluent. Finally, according to the nitrogen concentration monitored throughout the cycle of the device, the aeration volume is further decreased. Taking the complete removal of NH4 + -N at the end of aeration and the NO3 - -N concentration lower than 2 mg / L throughout the cycle as the critical point, stop decreasing the aeration volume, and complete the startup of the shortcut nitrification process.

[0008] When inoculating the secondary sedimentation tank sludge in step (1), the volume of the inoculated sludge accounts for 30% - 40% of the total volume of the reactor. In the initial mixed liquid formed by stirring, the total suspended solids are about 2500 - 3000 mg / L, and the ratio of volatile suspended solids to total suspended solids concentration in the initial mixed liquid is 0.4 - 0.7.

[0009] In step (1), the size of the polyurethane biological sponge carrier monomer added is 3 cm × 3 cm × 3 cm, and the total volume of the added carrier is 10-15% of the reactor volume.

[0010] In step (1), the temperature in the reactor is controlled at 25-30 °C, and the pH value is 7.5-8.0.

[0011] In step (1), the requirements for the carbon source culture medium substances and concentrations are as follows: the COD concentration is greater than or equal to 100 mg / L (CH3COONa is greater than or equal to 128.17 mg / L), the KHCO3 concentration is 1000 mg / L, and it also includes 60 mg / L CaCl2, 60 mg / L MgSO4·7H2O, and 1 ml / L of trace element solution. The concentrations of each trace element in the trace element solution are as follows: EDTA, 15000 mg / L; CoCl2·6H2O, 240 mg / L; ZnSO4·7H2O, 430 mg / L; MnCl2·2H2O, 990 mg / L; NaMoO4·2H2O, 220 mg / L; CuSO4·5H2O, 250 mg / L; Na2SeO4·10H2O, 210 mg / L; NiCl2·6H2O, 190 mg / L, and H3BO3, 14 mg / L.

[0012] In step (2), before the start of the device operation, the substances and concentrations of the synthetic wastewater to be introduced are as follows: the NH4 + -N concentration is 40-80 mg / L, and it needs to be the same as the NO3 - -N concentration in the reactor after being introduced together with the nitrate concentrate measured in the last cycle of step (1). The KHCO3 concentration is reduced to 700 mg / L, and the COD concentration is the same as the influent COD concentration in the last cycle of step (1). It also includes 9 mg / L PO4 3- -P, 60 mg / L CaCl2, 60 mg / L MgSO4·7H2O, and 1 ml / L of trace element solution. The substances and concentrations of the trace element solution are the same as those in step (1).

[0013] A short-cut nitrification process rapid startup device for implementing the above method. The reactor adopts a sequencing batch reactor, and the sequencing batch reactor is provided with a stirring device; a polyurethane biological sponge carrier; an aeration device; a water inlet bucket, which is connected to the sequencing batch reactor through a water inlet pipeline, and a water inlet pump and a water inlet valve are installed on the water inlet pipeline; a nitrate storage bucket, which is connected to the sequencing batch reactor through a nitrate delivery pipeline, and a liquid inlet pump and a liquid inlet valve are installed on the delivery pipeline; a drainage tank, the sequencing batch reactor is connected to the drainage tank through a drainage pipeline, and a drainage valve is installed on the drainage pipeline; an on-line monitoring and control device, which real-time monitors NH4 in the reactor + -N, NO3- -N, NO2 - The -N, DO concentration, and pH value can be adjusted according to the nitrogen concentration through the system settings of the self-regulating rotameter.

[0014] The method of the rapid-start short-cut nitrification process in the present invention is based on the timely reduction of NO2 generated during the PN process - -N can prevent the growth of NOB, and Candidatus Contendobacter has the performance of using stored PHA to carry out the denitrification process in a low-DO environment, providing a PN rapid-start method mainly based on biological assistance and supplemented by aeration and alkalinity regulation, solving the problem of the long start-up time of the PN process in the actual application process: First, inoculate the secondary sedimentation tank sludge in the SBR reactor and add polyurethane biological sponge carriers, and use the segmented influent + post-aeration increment (first increase the duration, then increase the aeration volume) strategy to drive Candidatus Contendobacter to migrate to the sponge carrier and complete enrichment and domestication by using nitrate and a dynamic oxygen environment. After that, cancel the segmented influent measure and change it to a single-pass synthetic wastewater mainly containing NH4 + -N, adopt a low-alkalinity (reduce the influent KHCO3 concentration) + post-aeration first increase and then decrease (aeration volume) strategy, and combine the strong NO2 of Candidatus Contendobacter in a low-dissolved oxygen environment - -N reduction ability to hinder the growth of NOB and assist the high-speed enrichment of AOB, thereby completing the rapid start-up of the PN process.

[0015] The device and method of the rapid-start short-cut nitrification process described in the present invention have the following advantages:

[0016] (1) Since both O2 and NO x - -N can be used as electron acceptors for Candidatus Contendobacter to consume the stored PHA in the cells, when directly starting the PN process by direct aeration at the beginning of operation, the prior presence of O2 makes it difficult for CandidatusContendobacte to exert its endogenous denitrification function in an aerobic environment, and thus it is impossible to successfully compete for NO2 - -N to hinder the growth of NOB. The segmented influent + post-aeration increment (duration and aeration volume) strategy of the present invention pre-cultivates activated sludge with NO3 - -N as the preferred electron acceptor and uses a dynamic oxygen environment to drive Candidatus Contendobacter to migrate to the sponge carrier and enrich, and Candidatus Contendobacter sludge and biofilm with reduced O2 interference can be obtained within 15 days.

[0017] (2) Adding polyurethane biological sponge carriers provides a locally anoxic area for Candidatus Contendobacter in an aerobic environment, which is more conducive to the denitrification process of Candidatus Contendobacter. Therefore, preferentially driving the enrichment of Candidatus Contendobacter in the sponge carriers can further promote Candidatus Contendobacter to capture NO2 - -N.

[0018] (3) After pre-cultivation, Candidatus Contendobacter still uses NO x - -N as the dominant electron acceptor in a low dissolved oxygen environment. Compared with NOB whose activity has not yet recovered, the NO2 - -N produced by AOB is preferentially reduced by Candidatus Contendobacter in a low DO environment, causing NOB to be eliminated due to lack of substrate, and thus creating advantageous conditions for the growth of AOB. The PN process can be initiated within 10 days based on the obtained Candidatus Contendobacter sludge and biofilm.

[0019] (4) In addition to the main auxiliary role of Candidatus Contendobacter, the multiple aeration and low alkalinity strategies further accelerate the start-up of the PN process. In the early stage, the interference of O2 to Candidatus Contendobacter is reduced by the strategy of increasing post-aeration incrementally (increasing duration first and then aeration volume). In the later stage, a low substrate and low dissolved oxygen environment is created by the strategy of low alkalinity (reducing the concentration of influent KHCO3) + increasing and then decreasing post-aeration (aeration volume) to reduce the available inorganic carbon source and O2 for NOB and promote the enrichment of AOB.

[0020] (5) Compared with the traditional method for starting the PN process, the starting method provided by the present invention, which is mainly assisted by Candidatus Contendobacter and supplemented by aeration and alkalinity regulation, can save costs such as long-term addition of chemical reagents, and has the characteristics of high efficiency, stability and no biological toxicity.

[0021] In order to make the technical solutions of the device and method for rapidly starting the shortcut nitrification process described in the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Description of the Drawings

[0022] As Figure 1 shown is a schematic diagram of the device for rapidly starting the shortcut nitrification process described in the present invention.

[0023] Among them, the reference numerals are:

[0024] 1 - SBR reactor; 11 - stirring device; 12 - aeration disk; 13 - rotameter; 14 - air pump; 15 - polyurethane biological sponge carrier; 2 - influent bucket; 3 - nitrate storage bucket; 4 - effluent bucket; 5 - on - line monitoring and control equipment; 6 - carbon source feed pump; 7 - feed pump. Specific implementation mode

[0025] The present invention will be further described below in conjunction with specific implementation examples, but the protection scope of the present invention is not limited thereto.

[0026] Example 1

[0027] This example provides a device for quickly starting a shortcut nitrification process, and its device structure is as Figure 1 shown, including an SBR reactor 1 with a working volume of 5L, equipped with a stirring device 11 and an aeration disk 12. The air pump 14 is connected to the aeration disk through a rotameter 13, and a polyurethane biological sponge carrier 15 is added to the reactor; the influent bucket includes an influent bucket 2 and a nitrate storage bucket 3, which are respectively connected to a feed pump 6 and a nitrate feed pump 7; the effluent bucket 4 is used to store the effluent of the reactor; the sensors of the on - line monitoring and control equipment 5 are installed inside the SBR reactor to realize the real - time monitoring of NH4 + -N, NO3 - -N, NO2 - -N, DO concentration and pH value during operation, and automatically regulate the rotameter 13 according to the nitrogen concentration through system settings.

[0028] When starting up the device, deionized water is used to prepare two kinds of influents for the pre - culture of Candidatus Contendobacter. Among them, the material components and concentrations of influent 1 (carbon source medium) are 138 - 150mg / L CH3COONa (108 - 117mg / L COD), 60mg / L CaCl2, 60mg / L MgSO4·7H2O, 1000mg / L KHCO3 and 1ml / L of trace element solution. The pH of the influent is maintained between 7.5 - 8.0 and placed in the influent bucket 2. Before the start of each cycle in step (1), 2.5L of the carbon source medium is pumped into the reactor through the feed pump 7. The material components and concentrations of influent 2 (nitrate concentrate) are 10000mg / L NO3 - -N, placed in the nitrate storage bucket 3. When running to 1 / 4 of the reaction cycle duration, 10mL of the nitrate concentrate is pumped into the device through the feed pump 6. After pumping, NO3 in the device -The concentration of -N is 40 mg / L. The COD concentration (117 mg / L) in the influent water of the last cycle in the calibration measurement step (1) and the NO3 - -N concentration (40 mg / L) in the device after the nitrate concentrate is introduced are used to prepare an influent water for the start-up of the PN process with deionized water. The composition and concentration of the substances in influent water 3 are 117 mg / L COD (150 mg / L CH3COONa), 40 mg / L NH4 + -N, 9 mg / L PO4 3- -P, 60 mg / L CaCl2, 60 mg / L MgSO4·7H2O, 700 mg / L KHCO3 and 1 ml / L of trace element solution. The pH of the influent water is maintained between 7.5 - 8.0 and placed in the influent water bucket 2. Before the start of each cycle operation in step (2), 2.5 L of influent water 3 is pumped into the reactor through the influent water pump 7. After a single cycle operation is completed and sludge sedimentation is finished, 2.5 L of the solution in the reactor is discharged to the effluent water bucket 4.

[0029] The concentrations of the components of each trace element in the trace element solution are as follows: EDTA, 15000 mg / L; CoCl2·6H2O, 240 mg / L; ZnSO4·7H2O, 430 mg / L; MnCl2·2H2O, 990 mg / L; NaMoO4·2H2O, 220 mg / L; CuSO4·5H2O, 250 mg / L; Na2SeO4·10H2O, 210 mg / L; NiCl2·6H2O, 190 mg / L and H3BO3, 14 mg / L.

[0030] The method for rapidly starting the shortcut nitrification process described in this embodiment is specifically as follows:

[0031] (1) Use the secondary sedimentation tank sludge as the inoculation sludge to inoculate into the SBR reactor. The volume of the inoculation sludge accounts for 30% of the total volume of the SBR reactor. The total suspended solids in the initial mixed liquor after influent water stirring is 2500 mg / L, and the ratio of volatile suspended solids to total suspended solids in the initial mixed liquor is 0.5. Add 20 polyurethane biological sponge carriers with a size of 3 cm × 3 cm × 3 cm, and the total volume of the added carriers is about 10% of the reactor volume. Set the drainage ratio of the SBR reactor to 50%, the operation cycle is 6 hours, and 2 cycles are operated every day.

[0032] Before the start of each cycle operation, 2.5 L of influent water 1 is introduced. For the first time, the C / N ratio is set to 2.7. When it reaches 1 / 4 of the reaction cycle duration, that is, at 1.5 hours, 10 mL of influent water 2 is introduced. After the influent water 2 is introduced, NO3 in the reactor -The concentration of -N is 40 mg / L; during the operation, the concentration of CH3COONa in influent 1 is increased in cycles until the total nitrogen removal rate is higher than 95%; on the 5th day when the C / N ratio is 2.9, the total nitrogen removal rate increases to 96.45%; subsequently, on the 6th day, a post-aeration increasing strategy (increasing the duration first and then the aeration volume) is adopted. Aeration starts after influent 2 is introduced, and the DO concentration in the reactor is controlled at 0.1 mg / L with an aeration duration of 1 h. Based on the condition that the total nitrogen removal rate of the system is higher than 95%, the aeration duration is increased in cycles, with a single increase of 0.5 h each time, and the increase of the aeration duration stops when the total nitrogen removal rate is lower than 95%; on the 7th day, the total nitrogen removal rate drops to 94.50%, and the increase of the aeration duration stops. At this time, the single-cycle aeration duration is 2.5 h, and the remaining 2 h of the reaction cycle operates in an anoxic state. After the aeration duration is determined, the aeration volume is increased step by step in cycles, with a single increase of 0.5 mg / L of dissolved oxygen in the corresponding device, and the critical points are 1 - 2 mg / L of DO and a total nitrogen removal rate lower than 90%; on the 10th day, the total nitrogen removal rate is 92.7%. The high-throughput test results show that the relative abundance of Candidatus Contendobacter in flocculent sludge is 28.25% and in biofilm is 37.65%, which is the most abundant species in sludge and biofilm, completing the pre-cultivation step of Candidatus Contendobacter. After measurement, the COD concentration in the influent of the last cycle and the NO3 - -N concentrations are 117 mg / L and 40 mg / L respectively, and the DO concentration in the device during aeration is 1.1 mg / L. The specific final process and influent process in this stage of this example are: at the initial stage of operation, influent 1 is introduced, and then the stirring process is carried out; after stirring for 1.5 h, influent 2 is introduced in 1 minute, and after influent 2 is introduced, the aeration and stirring process is carried out for 2.5 h; finally, only stirring operation is carried out for 2 h.

[0033] (2) Based on the Candidatus Contendobacter sludge and biofilm in step (1), influent 1 and 2 are not introduced, and 2.5 L of influent 3 is introduced before the start of each cycle. The influent COD concentration is the same as that of the last cycle in step (1) (117 mg / L), and the NH4 + -N concentration is the same as that in the device after the nitrate concentrate is introduced in the last cycle of NO3 -The concentration of -N is consistent (40 mg / L). The specific process and the water inlet process are as follows: At the initial stage of operation, water inlet 3 is introduced, and then a stirring process is carried out for 1.5 hours; subsequently, an aeration plus stirring process is carried out for 2.5 hours; finally, it only runs with stirring for 2 hours. Set the program of the on-line monitoring and control equipment to increase the aeration volume once during the 2.5-hour aeration period until the DO concentration in the reactor is the same as the DO concentration measured in the last cycle of step (1) (1.1 mg / L); when the reaction ends on the 15th day, the effluent does not contain NH4 + -N, and the nitrifying bacteria are activated, but the NO3 concentration in the effluent is - 6 mg / L. Taking the cycle as a unit, gradually reduce the aeration volume, and the change in the DO concentration per reduction does not exceed 0.2 mg / L; on the 18th day, the NH4 concentration in the effluent is + -N and NO3 - -N concentrations are both 0 mg / L, and the NO2 concentration is - 5.76 mg / L. At this time, the DO concentration in the reactor during aeration is 0.5 mg / L; the on-line monitoring and control equipment shows that there is a situation where the NO3 concentration is higher than 2 mg / L during the operation, so continue to gradually reduce the aeration volume. On the 20th day, the DO concentration in the reactor during aeration is lower than 0.2 mg / L. The real-time monitoring results show that there is no NH4 remaining in the water at the end of aeration - -N and throughout the operation, the NO3 concentration is + lower than 2 mg / L, which marks the successful start of the PN process. The high-throughput test results show that the relative abundance of the final AOB genus Nitrosomonas is 3.71 times that of the NOB genus Nitrospira, further confirming the successful start of the PN process. - In this example, the total start-up time is 20 days, including 10 days of pre-cultivation of Candidatus Contendobacter and 10 days of start-up of the PN process. The monitoring shows that after 30 days of operation, the PN process operates stably, and there is no NH4 remaining in the water at the end of aeration

[0034] -N, and the NO3 concentration in the reactor is always lower than 2 mg / L throughout the operation and the AOB continues to be enriched. + -N and throughout the operation, the NO3 concentration is - always lower than 2 mg / L and the AOB continues to be enriched.

[0035] Example 2

[0036] The short-cut nitrification process rapid start-up device in this example is the same as that in Example 1.

[0037] When the device starts up, deionized water is used to prepare two kinds of influent water for the pre-cultivation of Candidatus Contendobacter. Among them, the composition and concentration of influent water 1 (carbon source medium) are 277 - 308 mg / L CH3COONa (216 - 240 mg / L COD), 60 mg / L CaCl2, 60 mg / L MgSO4·7H2O, 1000 mg / L KHCO3 and 1 ml / L of trace element solution. The pH of the influent water is maintained between 7.5 - 8.0 and placed in the influent water bucket 2. Before the start of each cycle operation in step (1), 2.5 L of the carbon source medium is pumped into the reactor through the influent water pump 7. The composition and concentration of influent water 2 (nitrate concentrate) are 20000 mg / L NO3 - -N, placed in the nitrate storage bucket 3. When it runs to 1 / 4 of the reaction cycle duration, 10 mL of the nitrate concentrate is pumped into the reactor through the influent water pump 6. After pumping, the NO3 - -N concentration in the device is 80 mg / L. The COD concentration (240 mg / L) in the influent water of the last cycle in step (1) and the NO3 - -N concentration (80 mg / L) in the device after the nitrate concentrate is introduced are measured for comparison. Deionized water is used to prepare an influent water for the start-up of the PN process. Deionized water is used to prepare an influent water for the start-up of the PN process. The composition and concentration of influent water 3 are 308 mg / L CH3COONa (240 mg / L COD), 80 mg / L NH4 + -N, 9 mg / L PO4 3- -P, 60 mg / L CaCl2, 60 mg / L MgSO4·7H2O, 700 mg / L KHCO3 and 1 ml / L of trace element solution. The pH of the influent water is maintained between 7.5 - 8.0 and placed in the influent water bucket 2. Before the start of each cycle operation in step (2), 2.5 L of influent water 3 is pumped into the reactor through the influent water pump 7. After the single-cycle operation is completed and the sludge sedimentation is finished, 2.5 L of the solution in the reactor is discharged to the effluent water bucket 4.

[0038] The composition of the trace element solution is the same as that in Example 1.

[0039] The method for quickly starting up the shortcut nitrification process described in this example is specifically as follows:

[0040] (1) The secondary sedimentation tank sludge was used as the inoculated sludge to inoculate the SBR reactor. The volume of the inoculated sludge accounted for 30% of the total volume of the SBR reactor. The total suspended solids in the initial mixed liquor after influent stirring was 2,800 mg / L, and the ratio of volatile suspended solids to total suspended solids in the initial mixed liquor was 0.5. Twenty-five polyurethane biological sponge carriers with a size of 3 cm × 3 cm × 3 cm were added, and the total volume of the added carriers was about 13.5% of the reactor volume. The drainage ratio of the SBR reactor was set to 50%, the operating cycle was 8 hours, and 2 cycles were operated per day.

[0041] Before the start of each cycle operation, 2.5 L of influent 1 was introduced. The C / N ratio was initially set to 2.7. When the reaction cycle reached 1 / 4 of its duration, i.e., 2 hours, 10 mL of influent 2 was introduced. After the introduction of influent 2, the NO3 - -N concentration in the reactor was 80 mg / L; during the operation, the CH3COONa concentration in influent 1 was increased in units of cycles until the total nitrogen removal rate was higher than 95%; on the 6th day when the C / N ratio was 3.0, the total nitrogen removal rate increased to 98.21%; subsequently, on the 7th day, a post-aeration increment strategy (first increasing the duration and then the aeration volume) was adopted. Aeration started after the introduction of influent 2, and the DO concentration in the reactor was controlled at 0.1 mg / L, with an aeration duration of 1 h. Based on the condition that the total nitrogen removal rate of the system was higher than 95%, the aeration duration was increased in units of cycles, with a single increase of 0.5 h each time, and the increase of the aeration duration was stopped when the total nitrogen removal rate was lower than 95% as the critical point; on the 9th day, the total nitrogen removal rate decreased to 93.75%, and the increase of the aeration duration was stopped. At this time, the single-cycle aeration duration was 3 hours, and the remaining 3 hours of the reaction cycle were operated in an anoxic state; after the aeration duration was determined, the aeration volume was gradually increased in units of cycles, with a single increase of 0.5 mg / L in the DO in the corresponding device; on the 11th day, the total nitrogen removal rate was 91.34%. The high-throughput test results showed that the relative abundance of Candidatus Contendobacter in the flocculent sludge was 26.85%, and in the biofilm was 35.27%, which was the most abundant species in the sludge and biofilm, completing the pre-cultivation step of Candidatus Contendobacter. After measurement, the COD concentration in the influent of the last cycle and the NO3 - -N concentration in the device after the introduction of the nitrate concentrate were 240 mg / L and 80 mg / L respectively, and the DO concentration in the device during aeration was 1.6 mg / L. The specific procedures and influent process at the final stage in this example were as follows: At the beginning of the operation, influent 1 was introduced, and then the stirring process was carried out; after stirring for 2 hours, influent 2 was introduced in 1 minute. After the introduction of influent 2, the aeration plus stirring process was carried out for 3 hours; the last 3 hours were only operated with stirring.

[0042] (2) On the basis of Candidatus Contendobacter sludge and biofilm in step (1), the inflow of influent 1 and 2 is cancelled. Before the start of each cycle operation, 2.5 L of influent 3 is introduced. The influent COD concentration is the same as that in the last cycle of step (1) (240 mg / L), and the NH4 + -N concentration is the same as the NO3 - -N concentration in the device after the nitrate concentrate is introduced in the last cycle (80 mg / L). The specific process and influent process are as follows: At the initial stage of operation, influent 3 is introduced, and then a 2-hour stirring process is carried out; subsequently, a 3-hour aeration plus stirring process is carried out; finally, only stirring operation is carried out for 3 hours. Set the on-line monitoring and control equipment program, and increase the aeration volume once during the 3-hour aeration period until the DO concentration in the reactor is the same as the measured DO concentration in the last cycle of step (1) (1.6 mg / L); on the 16th day, after the reaction ends, the effluent does not contain NH4 + -N, the nitrifying bacteria are activated, but the NO3 - -N concentration in the effluent is 6.5 mg / L. Taking the cycle as a unit, gradually reduce the aeration volume, and the change in the DO concentration per reduction does not exceed 0.2 mg / L; on the 17th day, the NH4 + -N and NO3 - -N concentrations in the effluent are both 0 mg / L, and the NO2 - -N concentration is 6.94 mg / L. At this time, the DO concentration in the reactor during aeration is 0.4 mg / L; the on-line monitoring and control equipment shows that there is a situation where the NO3 - -N concentration is higher than 2 mg / L during operation, so continue to gradually reduce the aeration volume. On the 19th day, the DO concentration in the reactor during aeration is lower than 0.15 mg / L. The real-time monitoring results show that there is no NH4 + -N remaining in the water at the end of aeration and the NO3 - -N concentration is lower than 2 mg / L throughout the operation, which marks the successful start of the PN process. The high-throughput test results show that the relative abundance of the final AOB genus Nitrosomonas is 4.08 times that of the NOB genus Nitrospira, further confirming the successful start of the PN process.

[0043] The total start-up time of this example is 19 days, including 11 days of pre-cultivation of Candidatus Contendobacter and 8 days of start-up of the PN process. Monitoring shows that after 30 days of operation, the PN process operates stably, there is no NH4 + -N remaining in the water at the end of aeration, and the NO3 - -N concentration is always lower than 2 mg / L throughout the operation of the reactor and the AOB continues to be enriched.

[0044] Comparative example

[0045] This comparative example was conducted simultaneously with the experiment in Example 1 but had different experimental settings. The main difference was that Candidatus Contendobacter was not pre-cultured, and the PN process was started directly with a low alkalinity + post-aeration strategy of increasing and then decreasing (aeration volume). The specific start-up method in the comparative example was as follows:

[0046] (1) Inoculate the secondary sedimentation tank sludge into a 5L SBR reactor to make the total suspended solids in the reactor 2500mg / L, and the ratio of volatile suspended solids to total suspended solids in the initial mixed liquor is 0.5. Add 20 polyurethane biological sponge carriers with a size of 3cm×3cm×3cm, and the total volume of the added carriers is about 10% of the reactor volume.

[0047] (2) At the initial stage of operation, introduce 2.5L of synthetic wastewater composed of 150mg / L CH3COONa, 40mg / L NH4 + -N, 9mg / L PO4 3- -P, 60mg / L CaCl2, 60mg / L MgSO4·7H2O, 700mg / L KHCO3 and 1ml / L of trace element solution. Then carry out the stirring process. After stirring for 1.5 hours, carry out the aeration and stirring process for 2.5 hours, and finally stop aeration and stir for 2 hours.

[0048] (3) Set the program of the on-line monitoring and control equipment to increase the aeration volume to make the DO concentration in the reactor 1.1mg / L during the 2.5-hour aeration period; when the reactor runs to the 4th day, nitrification phenomenon appears during the aeration period, and the effluent NO2 - -N concentration is 0mg / L, NH4 + -N concentration is 6.74mg / L, NO3 - -N concentration is 13.06mg / L. At the same time, there is almost no total nitrogen reduction during the aeration period, indicating that Candidatus Contendobacter did not carry out the endogenous denitrification process during this period. When running to the 9th day, nitrification is significant, and there is no NH4 + -N remaining in the effluent, containing 10.5mg / L NO3 - -N and 1.8mg / L NO2 - -N. The denitrification contribution of Candidatus Contendobacter during the aeration period is still weak, and the denitrification process mainly occurs during the last 2-hour stirring process. Gradually reduce the aeration volume and try to start the PN process. When the reactor runs to the 19th day, the aeration level has reached the critical point where NH4 + -N cannot be completely removed by AOB and NOB after the end of the aeration process, and the dissolved oxygen concentration in the system is lower than 0.2mg / L at this time. At this time, the remaining NO3 -The concentration of -N (13.2 mg / L) is still higher than that of NO2 - -N (6.9 mg / L), and the PN process fails to start. Subsequently, the influent CH3COONa concentration (200 mg / L) was increased, attempting to drive Candidatus Contendobacter to store more internal carbon sources by increasing the supply of organic matter, and then drive its denitrification function during the aeration process. However, the effect was not significant, and only 2 mg / L of total nitrogen was removed. Finally, the formation of the polyurethane bio-sponge carrier biofilm was not obvious. The high-throughput sequencing results showed that the relative abundance of Candidatus Contendobacter in the sludge was only 5.23%, and the relative abundance of Nitrosomonas of the AOB genus was 0.21 times that of Nitrospira of the NOB genus. In summary, compared with the comparative example, the method for quickly starting the shortcut nitrification process in the present invention can significantly shorten the start-up time of the PN process.

[0049] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the claims.

Claims

1. A method for quickly starting a short-range nitration process, characterized in that: include: (1) Inoculating secondary sedimentation tank sludge into a sequencing batch device and adding a polyurethane bio-sponge carrier; Before each cycle, the carbon source culture medium was introduced, and the system operation cycle was set to 6-8 hours; when the stirring operation reached 1 / 4 of the reaction cycle, the nitrate concentrate was introduced to control the NO3 - -N concentration is 40-80mg / L; by adjusting the COD concentration of the carbon source culture medium within the range of C / N ratio of 2.7-3.0, COD is supplied by CH3COONa, and the control system is operated until the total nitrogen removal rate is higher than 95%; after that, a post-aeration increment strategy is adopted, that is, first increase the time and then increase the aeration volume. Aeration is started after the introduction of nitrate concentrate. The dissolved oxygen DO concentration in the system is initially controlled to be 0.1mg / L, the aeration time is 1h, and the remaining reaction cycle time continues to operate in anoxic state; on the basis of the total nitrogen removal rate of the system being higher than 95%, only the aeration time is increased, with the cycle as the unit, a single increase of 0.5h, and the total nitrogen removal rate is less than 95% as the critical point, and the aeration time is stopped; after the aeration time is determined, the aeration volume is increased step by step in the cycle, corresponding to a single increase of 0.5mg / L in the device, with 1-2mg / L DO and a total nitrogen removal rate of less than 90% as the critical point, and the high-throughput data results show that Candidatus When Contendobacter is the microbial genus with the highest abundance in the system, the Candidatus Contendobacter pre-culture is terminated; the COD concentration in the influent of the last cycle of this step and the NO3 in the device after the nitrate concentrate is introduced are measured. - -N concentration and DO concentration during aeration are used to determine the COD and NH4 in the subsequent steps of influent + -N concentration and aeration volume during aeration; (2) Based on the Candidatus Contendobacter sludge, biological carrier, and the determined cycle and aeration time obtained in step (1), the short-range nitrification process is started; specifically, before the operation of the device starts, synthetic wastewater is introduced, and aeration is started when the stirring operation is performed to 1 / 4 of the reaction cycle time; first, the aeration volume is increased once to maintain the DO concentration in the device consistent with the DO concentration measured in the last cycle of step (1); under this condition, the process is operated until the effluent is free of NH4 + -N remaining and NO3 - When the -N concentration is higher than 5mg / L, the aeration volume is reduced step by step in cycles, and the single DO concentration reduction does not exceed 0.2mg / L until the effluent is free of NH4 + -N and NO3 - -N residue; Finally, according to the nitrogen concentration of the whole cycle monitored by the device, the aeration volume is further reduced to NH4 + -N is completely removed and NO3 is removed throughout the cycle - When the -N concentration is lower than 2 mg / L, it is the critical point, and the reduction of aeration volume is stopped, completing the startup of the short-range nitrification process.

2. The method for quickly starting a short-cut nitration process according to claim 1, characterized in that: When the secondary sedimentation tank sludge is inoculated in step (1), the volume of the inoculated sludge accounts for 30% to 40% of the total volume of the reactor, the total suspended matter concentration in the initial mixed solution formed by stirring is 2500 to 3000 mg / L, and the volatile suspended matter / total suspended matter concentration ratio in the initial mixed solution is 0.4 to 0.

7.

3. The method for quickly starting a short-cut nitration process according to claim 1, characterized in that: The size of the polyurethane bio-sponge carrier monomer added in step (1) is 3cm×3cm×3cm, and the total volume of the added carrier is 10-15% of the reactor volume.

4. The method for quickly starting a short-cut nitration process according to claim 1, characterized in that: In step (1), the temperature in the reactor is controlled at 25-30° C. and the pH value is controlled at 7.5-8.

0.

5. The method for quickly starting a short-cut nitration process according to claim 1, characterized in that: In step (1), the carbon source culture medium material and concentration requirements are: COD concentration is greater than or equal to 100 mg / L, KHCO3 concentration is 1000 mg / L, and also includes 60 mg / L CaCl2, 60 mg / LMgSO4·7H2O and 1 ml / L trace element solution; wherein the concentration of each trace element in the trace element solution is as follows: EDTA, 15000 mg / L; CoCl2·6H2O, 240 mg / L; ZnSO4·7H2O, 430 mg / L; MnCl2·2H2O, 990 mg / L; NaMoO4·2H2O, 220 mg / L; CuSO4·5H2O, 250 mg / L; Na2SeO4·10H2O, 210 mg / L; NiCl2·6H2O, 190 mg / L and H3BO3, 14 mg / L; In step (2), before the device starts to operate, the synthetic wastewater material and concentration requirements are: NH4 + -N concentration is 40-80 mg / L, and needs to be passed into the reactor with the nitrate concentrate measured in the last cycle of step (1) - -N concentration is consistent, KHCO3 concentration is reduced to 700mg / L, COD concentration step (1) The last cycle of the influent COD concentration is consistent, and also includes 9mg / L PO4 3- -P, 60mg / L CaCl2, 60mg / L MgSO4·7H2O and 1ml / L trace element solution.

6. A quick start short-range nitration process device for implementing any of the methods described in claims 1-5, characterized in that: The reactor adopts a sequencing batch reactor, which is provided with a stirring device; a polyurethane biological sponge carrier; an aeration device; a water inlet bucket, which is connected to the sequencing batch reactor through a water inlet pipe, and a water inlet pump and a water inlet valve are installed on the water inlet pipe; a nitrate storage bucket, which is connected to the sequencing batch reactor through a nitrate delivery pipe, and a liquid inlet pump and a liquid inlet valve are installed on the delivery pipe; a drainage box, the sequencing batch reactor is connected to the drainage box through a drainage pipe, and a drainage valve is installed on the drainage pipe; an online monitoring and control device, which monitors the NH4 in the reactor in real time + -N、NO3 - -N, NO2 - -N, DO concentration and pH value, the system is set to self-regulate the rotor flowmeter according to the nitrogen concentration.

Images