A modified biochar and a preparation method and application thereof

Abstract

The present application relates to a kind of modified biochar and its preparation method and application, first step, using bamboo to prepare biochar;Second step, preparation modified biochar;Third step, take anaerobic ammonia oxidation flocculation sludge in reactor, and add modified biochar in reactor.Using the method of the present application, the addition of modified biochar promotes the rapid granulation of anaerobic ammonia oxidation flocculation sludge can improve the denitrification activity and stability of anaerobic ammonia oxidation system at the same time, quickly realize the granulation of anaerobic ammonia oxidation flocculation sludge, and improve the relative abundance of anaerobic ammonia oxidation bacteria, has good theoretical guiding significance and practical application value for the cultivation of anaerobic ammonia oxidation granular sludge.

Description

Technical Field

[0001] This invention relates to the field of rapid granulation technology for sewage treatment sludge, and in particular to a modified biochar, its preparation method, and its application. Background Technology

[0002] Anaerobic ammonia oxidation (AAO) can convert ammonia nitrogen and nitrite nitrogen into nitrogen gas and a portion of nitrate nitrogen under anaerobic conditions. Compared with traditional nitrification-denitrification processes, AAO can significantly reduce carbon source input (100%) and aeration volume (approximately 60%), exhibiting remarkable low-carbon characteristics.

[0003] However, the functional bacteria, anaerobic ammonia oxidizing bacteria, grow slowly (generation time is about 2 weeks). How to effectively retain anaerobic ammonia oxidizing bacteria is the key to the stable and reliable operation of this process.

[0004] Granular sludge has a high settling velocity, making it easy to separate from water and preventing sludge loss with the water. However, due to the low growth rate of anaerobic ammonia oxidizing bacteria, the formation time of anaerobic ammonia oxidation granular sludge is relatively long. Therefore, it is of great significance to find a way to quickly achieve the granulation of anaerobic ammonia oxidation flocculent sludge.

[0005] Chinese patent CN202111430554.1 discloses a method for rapidly increasing the activity and abundance of anaerobic ammonia oxidizing bacteria by adding redox activated biochar. The method involves adding redox activated biochar to low-abundance anaerobic ammonia oxidizing sludge, with the added amount being 3–14 g / L. This method can increase the denitrification activity and abundance of anaerobic ammonia oxidizing bacteria while simultaneously improving their abundance. However, the sludge used in this patent is granular sludge and unmodified biochar, and due to the extremely low growth rate of anaerobic ammonia oxidizing bacteria, the formation time of the granular anaerobic ammonia oxidizing sludge is relatively long. Summary of the Invention

[0006] The purpose of this invention is to provide a modified biochar, its preparation method, and its application. The modified biochar is used to promote the rapid granulation of anammox flocculent sludge, belonging to the field of rapid sludge granulation technology in wastewater treatment. The method of using modified biochar to promote the rapid granulation of anammox flocculent sludge according to this invention can rapidly achieve the granulation of anammox flocculent sludge while improving the denitrification activity and stability of the anammox system, and increasing the relative abundance of anammox bacteria. This has good theoretical guidance and practical application value for the cultivation of anammox granular sludge.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A modified biochar comprising biochar and anaerobic heterotrophic bacteria, wherein the anaerobic heterotrophic bacteria colonize the surface of the biochar.

[0009] Furthermore, the biochar is bamboo charcoal-based biochar.

[0010] This invention also provides a method for preparing modified biochar, the specific steps of which are as follows:

[0011] S1. Preparation of bamboo charcoal-based biochar using bamboo;

[0012] S2. Preparation of modified biochar: Sodium acetate solution containing anaerobic heterotrophic bacteria is added to the bamboo charcoal-based biochar obtained in step S1. The biochar is cultured in the dark with shaking, washed and dried to obtain modified biochar.

[0013] Furthermore, in step S1, the bamboo is sourced from local green bamboo in Lianyungang.

[0014] Furthermore, in step S1, the specific steps for preparing bamboo charcoal-based biochar using bamboo are as follows:

[0015] S1-1. Grind the bamboo into powder and then dry it;

[0016] S1-2. The powder dried in step S1-1 is carbonized in a vacuum tube furnace, sieved, washed and dried to obtain bamboo charcoal-based biochar.

[0017] Furthermore, in step S1-1, the drying temperature is 100-110℃, preferably 105℃, and the drying time is 20-30h, preferably 24h.

[0018] Furthermore, in step S1-2, the operation method of the vacuum tube furnace is as follows: first, the temperature is gradually increased at a rate of 5°C / min until the temperature reaches 400°C, and then the vacuum tube furnace is closed after maintaining this temperature for 2.5 hours. During this period, nitrogen gas is continuously introduced into the vacuum tube furnace to maintain an oxygen-deficient environment.

[0019] Furthermore, in steps S1-2, the particle size of the bamboo charcoal-based biochar is 100-300 μm.

[0020] Furthermore, in steps S1-2, the washing method is as follows: wash three times with deionized water and adjust the pH of the bamboo charcoal-based biochar to 7.47-7.53.

[0021] Furthermore, in steps S1-2, the drying temperature is 100-110°C, preferably 105°C, and the drying time is 20-30 hours, preferably 24 hours.

[0022] Further, in step S2, the sodium acetate solution is prepared by dissolving solid sodium acetate in tap water, where tap water contains trace amounts of anaerobic heterotrophic bacteria, and sodium acetate promotes the growth of these bacteria.

[0023] Furthermore, the COD of the sodium acetate solution is 180–220 mg / L, preferably 200 mg / L.

[0024] Furthermore, the ratio of bamboo charcoal-based biochar to sodium acetate is 14-16g:0.1g, preferably 15g:0.1g.

[0025] Furthermore, in step S2, the temperature for the light-protected shaking culture is 30–37°C, preferably 35°C;

[0026] The time is 6 to 8 days, preferably 7 days;

[0027] The oscillation speed is 120-180 rpm, preferably 150 rpm.

[0028] Furthermore, in step S2, the washing method is: washing three times with deionized water.

[0029] Furthermore, in step S2, the drying method is: natural air drying.

[0030] In addition, the present invention also provides an application of modified biochar, in which synthetic wastewater is added to anaerobic ammonia oxidation flocculent wet sludge, and then modified biochar is added to obtain an anaerobic ammonia oxidation system, which is then cultured in the dark with shaking to promote the rapid granulation of anaerobic ammonia oxidation flocculent sludge.

[0031] Furthermore, the final concentration of modified biochar in the anaerobic ammonia oxidation system is 8–12 g / L, preferably 10 g / L.

[0032] Furthermore, the final concentration of sludge in the anaerobic ammonia oxidation system is 1800–2200 mg / L, preferably 2000 mg / L.

[0033] The anaerobic ammonia oxidation flocculent wet sludge originated from the EGSB reactor.

[0034] The particle size of the anaerobic ammonia oxidation flocculent wet sludge is less than 200 μm.

[0035] Furthermore, the modified biochar is added in a single application.

[0036] Furthermore, the light-protected shaking culture temperature is 30–37°C, preferably 35°C;

[0037] The time is 55–65 days, preferably 60 days;

[0038] The culture pH is 7–8, preferably 7.3;

[0039] The oscillation speed is 120-180 rpm, preferably 150 rpm.

[0040] Furthermore, the synthetic wastewater contains the following components: NH4Cl 80-100 mg N / L and NaNO2 110-130 mg N / L.

[0041] Furthermore, the synthetic wastewater also contains the following components: KHCO3 0.9–1.1 g / L, KH2PO4 0.02–0.03 g / L, CaCl2 0.2–0.4 g / L, MgSO4·7H2O 0.2–0.4 g / L, FeSO4·7H2O 0.01–0.02 g / L, and 1 mL / L of concentrated trace element solution;

[0042] The trace element concentrate contains the following components: H3BO3 0.03~0.05g / L, CoCl2·2H2O 0.5~0.7g / L, CuSO4·5H2O 0.6~0.7g / L, ZnSO4·7H2O 1.1~1.2g / L, MnCl2·4H2O 0.4~0.5g / L, NiCl2·6H2O 0.4~0.5g / L, NaMoO4·2H2O 0.5~0.6g / L, and EDTA 7~8g / L.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] 1. This invention utilizes modified biochar as a carrier to rapidly achieve the granulation of anaerobic ammonia oxidation flocculent sludge. At the same time, it can also increase the abundance of anaerobic ammonia oxidation bacteria, which has good theoretical guiding significance and practical application value for the cultivation of anaerobic ammonia oxidation granular sludge.

[0045] 2. This invention helps to improve the denitrification activity, total nitrogen removal rate and stability of anaerobic ammonia oxidation systems.

[0046] 3. The modified biochar produced in this invention has a low production cost and only requires a one-time addition, resulting in a good cost-effectiveness ratio.

[0047] 4. The method of the present invention is simple and applicable to the rapid granulation of anaerobic ammonia oxidation flocculent sludge. Attached Figure Description

[0048] Figure 1 Scanning electron microscope image of biochar before modification;

[0049] Figure 2 These are scanning electron microscope images of modified biochar. The white circles indicate the presence of fungi on the surface of the biochar.

[0050] Figure 3 For blank control reactor R C Denitrification performance;

[0051] Figure 4 To add conventional biochar reactor R B Denitrification performance;

[0052] Figure 5 To add modified biochar to reactor R MB Denitrification performance;

[0053] Figure 6 The specific anaerobic ammonium oxidation activity of the three reactors;

[0054] Figure 7 For blank control reactor R C Particle size variation of anammox sludge;

[0055] Figure 8 To add conventional biochar reactor R B Particle size variation of anammox sludge;

[0056] Figure 9 To add modified biochar to reactor R MB Particle size variation of anammox sludge;

[0057] Figure 10 The relative abundance of anaerobic ammonia-oxidizing bacteria in the three reactors after 60 days of operation. Detailed Implementation

[0058] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0059] In the following embodiments, the bamboo is purchased from local green bamboo in Lianyungang.

[0060] In the following embodiments, the anammox flocculent wet sludge is taken from the EGSB reactor, and granular sludge is filtered out using a filter screen with a pore size of 200 μm. The moisture content of the anammox flocculent wet sludge is constant, so the mass of sludge in the anammox flocculent wet sludge can be calculated, and the amount of anammox flocculent wet sludge used can be determined according to the final concentration of the sludge.

[0061] In the following embodiments, the main components of the artificially prepared synthetic wastewater include NH4Cl, 90 mg N / L; NaNO2, 120 mg N / L; KHCO3, 1 g / L; KH2PO4, 0.025 g / L; CaCl2, 0.3 g / L; MgSO4·7H2O, 0.3 g / L; FeSO4·7H2O, 0.015 g / L; and a trace element concentrate of 1 mL / L.

[0062] The trace element concentrate contains (g / L): H3BO3, 0.035; CoCl2·2H2O, 0.6; CuSO4·5H2O, 0.625; ZnSO4·7H2O, 1.075; MnCl2·4H2O, 0.495; NiCl2·6H2O, 0.475; NaMoO4·2H2O, 0.55; EDTA, 7.5.

[0063] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0064] Example 1

[0065] See Figure 1 and Figure 2 This embodiment provides a method for preparing modified biochar, the specific steps of which are as follows:

[0066] (1) Preparation of bamboo charcoal-based biochar using bamboo:

[0067] 1) After grinding the bamboo into powder, dry it in an electric constant temperature drying oven at 105℃ for 24 hours.

[0068] 2) Carbonization is carried out in a multi-station vacuum tube furnace. The specific operation is as follows: First, the temperature is increased at a gradient of 5℃ / min until the temperature reaches 400℃, and then maintained at this temperature for 2.5h. After that, the tube furnace is closed. During this period, nitrogen is continuously introduced into the tube furnace to maintain an oxygen-deficient environment, and biochar is obtained.

[0069] 3) The obtained biochar was sieved to separate biochar of 100-300 μm.

[0070] 4) Wash the bamboo charcoal-based biochar samples with a particle size of 100-300 μm three times with deionized water, adjust the pH to 7.50±0.03, dry at 105℃ for 24 h, and store in a desiccator.

[0071] (2) Preparation of modified biochar:

[0072] 15g of bamboo charcoal-based biochar was placed in a 500mL serum bottle. Sodium acetate solution prepared with tap water was added to the bottle and the volume was adjusted to 500mL. The final COD of the sodium acetate solution in the serum bottle was 200mg / L. The mixture was then cultured in a shaker at 35℃ and 150rpm in the dark for 7 days under sealed conditions. The biochar after the reaction was removed, washed three times with deionized water, and air-dried naturally to obtain modified biochar, which was then stored in a desiccator.

[0073] like Figure 1 and Figure 2 As shown, bacteria are clearly attached to the pores of the modified biochar, indicating that after modification, anaerobic heterotrophic bacteria have successfully colonized the surface of the biochar.

[0074] Example 2

[0075] This embodiment provides an application of modified biochar, and the specific steps are as follows:

[0076] Add 100 mL of anaerobic ammonia oxidation flocculent wet sludge to a 500 mL serum bottle, and add artificially prepared synthetic wastewater to make the final concentration of the mixed sludge in the serum bottle 2000 mg / L.

[0077] Add modified biochar (serum bottle number R) MB The final concentration of the modified biochar in the serum bottle was 10 g / L, and it was cultured in a shaker at 35°C and 150 rpm in the dark for 60 days.

[0078] Comparative Example 1

[0079] This comparative example provides an application of common biochar, with the specific steps as follows:

[0080] Add 100 mL of anaerobic ammonia oxidation flocculent wet sludge to a 500 mL serum bottle, and add artificially prepared synthetic wastewater to make the final concentration of the mixed sludge in the serum bottle 2000 mg / L.

[0081] Add regular biochar (serum bottle number R) B The final concentration of the modified biochar in the serum bottle was 10 g / L, and it was cultured in a shaker at 35°C and 150 rpm in the dark for 60 days.

[0082] In this comparative example, the common biochar is the bamboo charcoal-based biochar prepared in Example 1.

[0083] Comparative Example 2

[0084] This comparative example is a blank control (serum bottle number R). C The specific steps are as follows:

[0085] Add 100 mL of anaerobic ammonia oxidation flocculent wet sludge to a 500 mL serum bottle, and add artificially prepared synthetic wastewater to make the final concentration of the mixed sludge in the serum bottle 2000 mg / L. Incubate in a shaker at 35℃ and 150 rpm in the dark for 60 days.

[0086] The performance of the anaerobic ammonia oxidation flocculent wet sludge cultured in Example 2, Comparative Example 1, and Comparative Example 2 was tested, as follows:

[0087] Depend on Figures 3 to 5 It can be seen that the addition of modified biochar in Example 2 can significantly improve the total nitrogen removal efficiency of the anaerobic ammonia oxidation system, which is 28.6% and 271.1% higher than the blank control of Comparative Example 2 and the experimental group with added ordinary biochar in Comparative Example 1, respectively.

[0088] Therefore, the addition of modified biochar significantly improved the stability of the anaerobic ammonia oxidation system. During long-term operation, the total nitrogen removal efficiency was the most stable, and the activity of bacteria in the system with ordinary biochar added in Comparative Example 1 was inhibited.

[0089] Depend on Figure 6 It can be seen that the addition of modified biochar in Example 2 significantly improved the specific anammox activity of the anammox system. On days 10, 30, and 60, R... MB The specific anaerobic ammonium oxidation activities were 269.9±22.2, 175.2±7.9, and 175.5±13.4 mg N / g VSS / d, respectively, all significantly higher than those of R. C (217.2±13.2, 65.9±6.5 and 104.1±19.2 mg N / g VSS / d) and R B (249.1±5.6, 63.9±2.5 and 39.5±5.9 mg N / g VSS / d).

[0090] Depend on Figures 7 to 9 It can be seen that the addition of modified biochar in Example 2 significantly increased the particle size of the anammox granular sludge. After 60 days of cultivation, R MB The average particle size of the anaerobic ammonia oxidation granular sludge was 487±12 μm, significantly higher than that of R. C 300±6μm and R B 290±3μm.

[0091] Depend on Figure 10 It can be seen that the addition of modified biochar in Example 2 significantly increased the relative abundance of anaerobic ammonia-oxidizing bacteria. After 60 days of cultivation, R MB The relative fraction of unclassified_f_Brocadiaceae (denitrifying functional bacteria) anaerobic ammonia oxidizing bacteria was 1.6%, significantly higher than that of R. C 0.1% and RB 0.9%.

[0092] Therefore, the method of using modified biochar to promote the rapid granulation of anammox flocculent sludge according to the present invention can rapidly achieve the granulation of anammox flocculent sludge while improving the denitrification activity and stability of the anammox system, and increase the relative abundance of anammox bacteria. It has good theoretical guidance significance and practical application value for the cultivation of anammox granular sludge.

[0093] 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 method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge, characterized in that, The modified biochar includes bamboo charcoal-based biochar and anaerobic heterotrophic bacteria, wherein the anaerobic heterotrophic bacteria colonize the surface of the bamboo charcoal-based biochar. The modified biochar is prepared as follows: S1. Bamboo-based biochar with a particle size of 100~300 μm is prepared using bamboo. The specific steps are as follows: S1-1. Grind the bamboo into powder and then dry it; S1-2. The powder dried in step S1-1 is carbonized in a vacuum tube furnace, sieved, washed and dried to obtain bamboo charcoal-based biochar. The operation method of the vacuum tube furnace is as follows: First, the temperature is gradually increased at a rate of 5 °C / min until the temperature reaches 400 °C, and then the vacuum tube furnace is closed after maintaining this temperature for 2.5 h. During this period, nitrogen gas is continuously introduced into the vacuum tube furnace to maintain an oxygen-deficient environment. The washing method is as follows: wash three times with deionized water and adjust the pH of the bamboo charcoal-based biochar to 7.47~7.53; The drying temperature is 100~110 ℃, and the drying time is 20~30 h; S2. Preparation of modified biochar: Add sodium acetate solution containing anaerobic heterotrophic bacteria to the bamboo charcoal-based biochar obtained in step S1, culture with shaking in the dark, wash, and dry to obtain modified biochar. In step S2, the COD of the sodium acetate solution is 180~220 mg / L, and the sodium acetate solution is prepared using tap water; the ratio of bamboo charcoal-based biochar to sodium acetate is 14~16 g: 0.1 g. The method for promoting the granulation of anaerobic ammonia oxidation flocculent sludge is as follows: Synthetic wastewater was added to anaerobic ammonia oxidation flocculent wet sludge, followed by modified biochar, to obtain an anaerobic ammonia oxidation system. The system was then cultured in the dark with shaking to promote the rapid granulation of the anaerobic ammonia oxidation flocculent sludge.

2. The method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge according to claim 1, characterized in that, In step S1-1, the drying temperature is 100~110 ℃ and the drying time is 20~30 h.

3. A method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge according to claim 1, characterized in that, In step S2, the light-protected oscillation culture temperature is 30~37 ℃, the time is 6~8 days, and the oscillation speed is 120~180 rpm; The washing method involves washing three times with deionized water. The drying method is natural air drying.

4. A method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge according to claim 1, characterized in that, The final concentration of modified biochar in the anaerobic ammonia oxidation system is 8~12 g / L.

5. A method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge according to claim 1, characterized in that, The final concentration of sludge in the anaerobic ammonia oxidation system is 1800~2200 mg / L.

6. A method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge according to claim 1, characterized in that, The anaerobic ammonia oxidation flocculent wet sludge originated from the EGSB reactor; The particle size of the anaerobic ammonia oxidation flocculent wet sludge is less than 200 μm; The modified biochar is added in a single application. The light-protected shaking culture was conducted at a temperature of 30-37 °C for 55-65 days, with a pH of 7-8 and a shaking speed of 120-180 rpm.

7. A method for using modified biochar to promote the granulation of anaerobic ammonia oxidation flocculent sludge according to claim 1, characterized in that, The synthetic wastewater contains the following components: NH4Cl 80~100 mg N / L and NaNO2 110~130 mg N / L.

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