Device and method for in-situ granulation of autotrophic denitrification functional bacteria

Abstract

The application relates to a device and a method for strengthening in-situ granulation of autotrophic denitrification functional bacteria, wherein the device comprises a nitrogen inlet water tank, a sodium sulfide inlet water tank, an autotrophic denitrification sequencing batch reactor and a drainage tank. The method comprises the following steps: establishing the autotrophic denitrification sequencing batch reactor, so that the autotrophic denitrification sequencing batch reactor has an anaerobic ammonia oxidation reaction function; when 10 mg S 2‑ / L of sodium sulfide is added into water, autotrophic denitrification functional bacteria are significantly promoted to form granules, and high-efficiency operation of the autotrophic denitrification process is ensured. Compared with the prior art, the application promotes in-situ granulation of autotrophic denitrification functional bacteria, improves total nitrogen removal efficiency in the autotrophic denitrification system, ensures long-term stable operation of the autotrophic denitrification process, has the advantages of small occupation, low investment cost, simple and practical process, no secondary pollution and the like, and further promotes application of the autotrophic denitrification process in treatment of sulfur-containing wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a device and method for in-situ granulation of autotrophic denitrification functional bacteria. BACKGROUND

[0002] Completely autotrophic nitrogen removal technology (CANON) is a nitrogen removal process independent of organic matter. It has attracted much attention due to its advantages such as low material addition, low energy consumption and low sludge production. This technology breaks through the limitation of high demand for organic carbon in traditional biological denitrification process, significantly reduces the cost of biological wastewater treatment and the emission of greenhouse gases. In recent years, CANON has been widely used in the treatment of waste water such as landfill leachate and sludge digestion liquid. So far, practical engineering of CANON has been widely used in the world. Anaerobic ammonium oxidation (Anammox) process refers to a process in which anaerobic ammonium oxidation bacteria can directly convert ammonia to nitrogen gas using nitrite as an electron acceptor under anaerobic or anoxic conditions. This process has the advantages of low energy consumption, no need for external carbon source, reduction of greenhouse gas emission and low sludge production, and has become a research hotspot in the field of biological denitrification.

[0003] However, autotrophic denitrification functional bacteria, such as anaerobic ammonium oxidation bacteria, have long doubling time (about 2-12 days), long growth cycle and are sensitive to environmental changes, which still limit the wide application of CANON. Therefore, effectively retaining autotrophic denitrification functional bacteria is a key factor to maintain stable and efficient operation of the reactor. Granulation of functional microorganisms is one of the effective ways to solve this problem. Autotrophic denitrification functional bacteria granules have the advantages of high biological density, high total nitrogen removal load and strong resistance to adverse environments, and have become the most promising sludge form for CANON application. Currently, methods for promoting microbial granulation, such as increasing the concentration of inorganic salt ions (Ca 2+ , Mg 2+ , etc.) and adding inert condensation nuclei (zeolite particles, activated carbon, etc.), have the problem of high cost. SUMMARY

[0004] The present application relates to the technical field of sewage treatment, and particularly relates to a device and method for in-situ granulation of autotrophic denitrification functional bacteria.

[0005] The object of the present application can be achieved by the following technical solutions:

[0006] One of the present application provides a device for in-situ granulation of autotrophic denitrification functional bacteria, comprising an autotrophic denitrification sequencing batch reactor (hereinafter referred to as "reactor"), a water inlet assembly, a drainage tank, a magnetic stirrer, a heating rod and a gas collection bag;

[0007] The water inlet assembly and the water outlet assembly are connected with the reactor through pipelines, and a peristaltic pump is arranged on the pipeline;

[0008] The magnetic stirrer is placed on the reactor, the heating rod is placed in the reactor, and the gas collection bag is arranged on the upper part of the reactor for collecting nitrogen;

[0009] The water inlet assembly is a water inlet tank, and the water inlet tank has two, one is a nitrogen inlet tank, and the other is a sodium sulfide inlet tank.

[0010] The second aspect of the present application provides a culture method for realizing granulation of autotrophic denitrification functional bacteria by the device for in-situ granulation of autotrophic denitrification functional bacteria, comprising the following steps:

[0011] S1: Start the reactor: inoculate the pretreated anaerobic ammonia oxidation sludge into the reactor, add a nutrient solution containing NH4 + -N and NO2 – -N, and obtain autotrophic denitrification functional bacteria;

[0012] S2: Add sodium sulfide: after the reactor is started stably, continue to add a nutrient solution containing NH4 + -N and NO2 – -N, and add Na2S·9H2O to the reactor to obtain granulated autotrophic denitrification functional bacteria.

[0013] The Na2S·9H2O is used to increase the particle size of the autotrophic denitrification functional bacteria, so as to obtain the granulated autotrophic denitrification functional bacteria.

[0014] Further, the pretreatment in step S1 is specifically that the anaerobic ammonia oxidation sludge with good nitrogen removal performance for a long time is washed several times with a phosphate buffer solution.

[0015] Further, the volatile suspended solid concentration in the anaerobic ammonia oxidation sludge in step S1 is 2500-3500 mg / L.

[0016] Further, in step S1, the concentration of NH4 + -N in the water inlet tank into the autotrophic denitrification functional bacteria system is 50-100 mg N / L, and the concentration of NO2 – -N is 66-150 mg N / L.

[0017] Further, in step S2, the concentration of NH4 +The concentration of N is 100 mg N / L, NO2 – The concentration of N is 150 mg N / L.

[0018] Further, the nutrient solution in step S1 is specifically composed of NH4Cl: NaNO2: KHCO3: KH2PO4: CaCl2: MgSO4·7H2O: FeSO4·7H2O: Na2EDTA: trace element concentrate = 66-133 mg / L: 103-207 mg / L: 1 g / L: 0.025 g / L: 0.3 g / L: 0.3 g / L: 0.00625 g / L: 0.00625 g / L: 0.5 mL / L, and the balance is water.

[0019] Further, the trace element concentrate in step S1 comprises, in g / L: H3BO3, 0.035; CoCl2, 0.525; CuSO4·5H2O, 0.625; ZnSO4·7H2O, 1.075; MnCl2·4H2O, 2.475; NiCl2·6H2O, 0.475; NaMoO4·2H2O, 0.55; Na2EDTA, 15; and the balance is water.

[0020] Further, the dosage of Na2S·9H2O in step S2 is 1-15 mg S 2- / L.

[0021] Further, the dosage of Na2S·9H2O in step S2 is preferably 10 mg S 2- / L.

[0022] Further, the sludge in step S1 is an anaerobic ammonia oxidation sludge that has maintained good nitrogen removal performance for a long time, and the total nitrogen removal efficiency of the reactor is maintained at 88%-90% for a long time.

[0023] Further, the temperature of the reactor in step S2 is controlled at 29-31℃.

[0024] Further, the pH value of the nitrogen inlet tank in step S2 and the sodium sulfide inlet tank in step S3 is controlled at 7.4-7.6.

[0025] Further, the stable start-up in step S3 is running for 30 days.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] (1) The addition of sodium sulfide in the present application promotes the granulation of autotrophic denitrification functional bacteria.

[0028] (2) The addition of sodium sulfide in the present application improves the total nitrogen removal performance of the autotrophic denitrification process and realizes long-term stable and efficient operation.

[0029] (3) The method of the present application is simple to operate, and the sodium sulfide dosage is low, which does not have a negative impact on the autotrophic denitrification process, and is convenient for long-term use in engineering.

[0030] (4) The method of the present application has the advantage of sustainability, and the sodium sulfide can be sourced from industrial wastewater, which has the advantages of economic efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The schematic diagram of the device for in-situ granulation of the autotrophic denitrification functional bacteria provided in the embodiment of the present application is shown in the figure.

[0032] Figure 2 The reactor inlet and outlet water nitrogen concentration result schematic diagram in the autotrophic denitrification functional bacteria granulation process provided in the embodiment of the present application is shown in the figure.

[0033] Figure 3 The total nitrogen performance result in the autotrophic denitrification functional bacteria granulation process provided in the embodiment of the present application is shown in the figure.

[0034] Figure 4 The particle size change schematic diagram in the autotrophic denitrification functional bacteria granulation process provided in the embodiment of the present application is shown in the figure.

[0035] Figure 5 The schematic diagram of the device for in-situ granulation of the autotrophic denitrification functional bacteria provided in the comparative example of the present application is shown in the figure.

[0036] Figure 6 The particle size change schematic diagram in the autotrophic denitrification functional bacteria granulation process provided in the comparative example of the present application is shown in the figure.

[0037] The figure is marked as: 1, sodium sulfide inlet water tank; 2, nitrogen inlet water tank; 3, peristaltic pump; 4, heating rod; 5, gas collection bag; 6, drain tank; 7, magnetic stirrer. DETAILED DESCRIPTION

[0038] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0039] EMBODIMENT

[0040] The present embodiment provides a running method of the device for granulation of the autotrophic denitrification functional bacteria.

[0041] The embodiment provides a device for strengthening granulation of autotrophic denitrification functional bacteria, which comprises an autotrophic denitrification sequencing batch reactor (referred to as a reactor), a water inlet assembly, a drainage tank 6, a magnetic stirrer 7, a heating rod 4 and a gas collection bag 5; the water inlet assembly and the water outlet assembly are connected with the reactor through pipelines, and a peristaltic pump 3 is arranged on the pipelines; the stirrer is placed with the reactor, the heating rod 4 is placed in the reactor, and the gas collection bag 5 is arranged at the upper portion of the reactor and used for collecting nitrogen; the water inlet assembly is a water inlet tank, and there are two water inlet tanks, one is a nitrogen inlet tank 2, and the other is a sodium sulfide inlet tank 1. The nitrogen inlet tank 2 provides NH4Cl and NaNO2 for the system; the sodium sulfide inlet tank 1 provides Na2S·9H2O for the system, as shown in Figure 1

[0042] The device for strengthening in-situ granulation of autotrophic denitrification functional bacteria realizes the culture method of the autotrophic denitrification functional bacteria granulation, and the culture method is as follows:

[0043] First step, sludge pretreatment.

[0044] The autotrophic denitrification system of the experiment is an anaerobic ammonia oxidation process, and the required seed sludge in the laboratory is taken from anaerobic ammonia oxidation sludge with good nitrogen removal performance for a long time. The active sludge is washed three times by using 0.1 mM phosphate buffer solution (PBS), and is placed in a 1L reactor for experiment. The volatile suspended solid concentration of the active sludge is determined, and the PBS is used to adjust to about 3000±500 mg / L, and nitrogen gas is exposed for 20 min to keep the reactor in an anoxic state.

[0045] Second step, start the reactor.

[0046] The temperature of the working zone of the reactor is controlled to be about 30℃, and the pH of the water inlet is adjusted to 7.5±0.1. The reactor is operated for 3 cycles per day, and one cycle is 8h, in which the water inlet is 5min, the stirring is 380min, the standing and sedimentation are 60min, the water drainage is 20min, and the idling is 5min. The water inlet is in the form of artificial water preparation every day, the initial NH4 + -N concentration is 50mg N / L, the NO2 - -N concentration is 66mg N / L, the NH4 + -N concentration is 100mg N / L, the NO2 - ​- N concentration was 135 mg N / L. The concentration of sodium sulfide was varied with the conditions of the running stage. The running conditions are shown in Table 1. Other elements included (g / L): KHCO3 1; KH2PO4, 0.025; CaCl2, 0.3; MgSO4·7H2O, 0.3; FeSO4·7H2O, 0.00625; Na2EDTA, 0.00625 and trace element concentrate 0.5 mL / L. The trace element concentrate included (g / L): H3BO3, 0.035; CoCl2, 0.525; CuSO4·5H2O, 0.625; ZnSO4·7H2O, 1.075; MnCl2·4H2O, 2.475; NiCl2·6H2O, 0.475; NaMoO4·2H2O, 0.55; Na2EDTA, 15. The concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen were determined by taking water samples with a syringe every three days to calculate the total nitrogen removal efficiency (TNRE). After running for 30 days, the autotrophic denitrification process was successfully started, the total nitrogen removal efficiency reached 88%, and the running effect is shown in Figure 2 and Figure 3 .

[0047] Table 1 running parameters of each stage

[0048]

[0049] Third step, adding sodium sulfide.

[0050] After the autotrophic denitrification process was stably started (running for 30 days), sodium sulfide was added to the influent, and the running conditions are shown in Table 1. The nitrogen removal performance of the autotrophic denitrification process and the particle size distribution of the functional microorganisms thereof were determined in each stage. During the running process, the nitrogen removal performance of the reactor is shown in Figure 2 . It can be known from Figure 3 that the total nitrogen removal efficiency gradually increased with the gradual increase of the concentration of sodium sulfide. When the concentration of sodium sulfide was 10 mg S 2- / L (stage III), the total nitrogen removal efficiency reached 96%. And in the running stage with the concentration of sodium sulfide of 10 mg S 2- / L, the formation of autotrophic denitrification functional bacteria particles was observed. Subsequently, the concentration of sodium sulfide was increased to 15 mg S 2- / L (stage IV), nitrate nitrogen accumulated in the effluent, and the total nitrogen removal efficiency decreased to 88%. Then, the concentration of sodium sulfide was reduced to 10 mg S 2- / L (stage V), the total nitrogen removal efficiency of the autotrophic denitrification process recovered to 95%-96% in the stable running.

[0051] The particle size change of sludge particles in the autotrophic denitrification process in different running stages is shown in Figure 4 . It can be known from Figure 4It can be known that 10mg S 2- The addition of sodium sulfide significantly increased the particle size of autotrophic denitrifying bacteria. In stage III, the average particle size D[4.3] of the autotrophic denitrifying bacteria was 833 μm, which was significantly higher than the average particle size D[4.3] of 78.3 μm of the autotrophic denitrifying bacteria without sodium sulfide (stage I). When the concentration of sodium sulfide was increased to 15 mg S 2- At a concentration of / L, the effect on the granulation of autotrophic denitrifying bacteria is relatively small.

[0052] Depend on Figures 2 to 4 It was found that the addition of sodium sulfide promoted the granulation of autotrophic denitrifying bacteria, increasing the average particle size of these bacteria by 969% to 833 μm; and ensuring long-term, efficient, and stable operation of the reactor, maintaining a total nitrogen removal rate of 95%–96%. The granulation of the autotrophic denitrifying bacteria improved the reactor's resistance to substrate concentration fluctuations, further expanding the application scope of the autotrophic denitrification process. Meanwhile, the optimal sodium sulfide dosage was 10 mg S. 2- / L.

[0053] Comparative Example

[0054] like Figure 5 As shown, the comparative example operates under the same conditions as the example, except that no sulfides are added.

[0055] The total nitrogen removal performance of this comparative autotrophic denitrification system remained stable during operation, with the effluent total nitrogen concentration maintained at 25–30 mg N / L and the total nitrogen removal efficiency maintained at 87%–89%. The changes in sludge particle size at different operating stages of this comparative autotrophic denitrification process are shown below. Figure 6 As shown in the figure, the particle size of the autotrophic denitrifying bacteria in the comparative example remained stable, with an average particle size D[4.3] of 80 μm at different stages. The results of the comparative experiment further demonstrate that the addition of sodium sulfide can promote the granulation of autotrophic denitrifying bacteria and ensure the long-term efficient and stable operation of the reactor.

[0056] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A device for in-situ granulation of enhanced autotrophic denitrifying bacteria and a method for granulating autotrophic denitrifying bacteria, characterized in that, The device includes an autotrophic denitrification sequencing batch reactor, an inlet water assembly, a drain tank (6), a magnetic stirrer (7), a heating rod (4), and a gas collection bag (5); The inlet and outlet components are connected to the sequencing batch reactor via pipelines, and a peristaltic pump (3) is installed on the pipelines. The magnetic stirrer (7) is placed on a sequencing batch reactor, the heating rod (4) is placed inside the sequencing batch reactor, and the gas collection bag (5) is set on the upper part of the sequencing batch reactor for collecting nitrogen. The water inlet assembly is a water inlet tank, and there are two water inlet tanks, one is a nitrogen water inlet tank (2) and the other is a sodium sulfide water inlet tank (1). The cultivation method includes the following steps: S1: Start the autotrophic nitrogen removal sequencing batch reactor: Inoculate the pretreated anaerobic ammonium oxidation sludge into the autotrophic nitrogen removal sequencing batch reactor, and add NH4+-containing... + -N and NO2 – -N nutrient solution yields autotrophic denitrifying bacteria; S2: Add sodium sulfide: After the autotrophic denitrification sequencing batch reactor has been stably started up, continue to add sodium sulfide containing NH4+. + -N and NO2 – The nutrient solution was enriched with -N, and Na2S·9H2O was added to the autotrophic denitrification sequencing batch reactor. The dosage of Na2S·9H2O was 10 mg S. 2- / L, to obtain granular autotrophic denitrifying bacteria; The Na2S·9H2O is used to increase the particle size of autotrophic denitrifying bacteria, thereby obtaining granular autotrophic denitrifying bacteria.

2. The method for cultivating autotrophic denitrifying bacteria by in-situ granulation of a device for enhancing autotrophic denitrification as described in claim 1, characterized in that, The pretreatment described in step S1 is as follows: washing the anaerobic ammonia oxidation sludge several times with a phosphate buffer solution; After pretreatment, the concentration of volatile suspended solids in the anaerobic ammonia oxidation sludge is 2500~3500 mg / L.

3. The method for cultivating autotrophic denitrifying bacteria by in-situ granulation of the device for enhancing autotrophic denitrification as described in claim 1, characterized in that, In step S1, the nitrogen inlet tank (2) feeds NH4 into the autotrophic denitrification bacteria system. + The concentration of -N is 50~100 mg N / L, NO2 – The concentration of -N is 66~150 mg N / L.

4. The method for cultivating autotrophic denitrifying bacteria by in-situ granulation of a device for enhancing autotrophic denitrification as described in claim 1, characterized in that, In step S2, NH4 is introduced into the granular autotrophic denitrification bacteria system from the nitrogen inlet tank (2). + The concentration of -N is 100 mg N / L, NO2 – The concentration of -N is 150 mg N / L.

5. The method for cultivating autotrophic denitrifying bacteria by in-situ granulation of a device for enhancing autotrophic denitrification bacteria according to claim 1, characterized in that, The nutrient solution described in step S1 has the following specific composition: NH4Cl: NaNO2: KHCO3: KH2PO4: CaCl2: MgSO4·7H2O: FeSO4·7H2O: Na2EDTA: Trace element concentrate = 66-133 mg / L: 103-207 mg / L: 1 g / L: 0.025 g / L: 0.3 g / L: 0.3 g / L: 0.00625 g / L: 0.00625 g / L: 0.5 mL / L, with the remainder being water.

6. The method for cultivating autotrophic denitrifying bacteria by in-situ granulation of a device for enhancing autotrophic denitrification as described in claim 5, characterized in that, The trace element concentrate, in g / L, comprises: H3BO3, 0.035; CoCl2, 0.525; CuSO4·5H2O, 0.625; ZnSO4·7H2O, 1.075; MnCl2·4H2O, 2.475; NiCl2·6H2O, 0.475; NaMoO4·2H2O, 0.55; Na2EDTA, 15; with the balance being water.

7. The method for cultivating autotrophic denitrifying bacteria by in-situ granulation of a device for enhancing autotrophic denitrification as described in claim 1, characterized in that, The stable start-up described in step S2 is the operation of the autotrophic denitrification sequencing batch reactor for 30 days.

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