Method for enhancing nitrogen removal performance of sulfur autotrophic denitrification at low temperature

Abstract

The invention discloses a method for enhancing the nitrogen removal performance of sulfur autotrophic denitrification at low temperature, which comprises the following steps: carrying out specific domestication culture on anaerobic sludge to obtain sulfur-enriched autotrophic bacteria sludge; the method comprises the following steps: inoculating sludge enriched with sulfur autotrophic bacteria into a sulfur autotrophic reactor for sewage treatment, and regularly adding an oxidation-reduction couple, namely anthraquinone-2, 6-sodium disulfonate / H2O2, into the sulfur autotrophic reactor when the environment temperature is in a low-temperature environment of 10-20 DEG C; according to the present invention, the exogenous redox couple-anthraquinone-2, 6-sodium disulfonate / H2O2 is added into the sulfur autotrophic denitrification system at the low temperature of 10-20 DEG C, such that the electron transfer efficiency and the sulfur autotrophic flora metabolism activity are improved, and the synthesis of the intracellular resources ATP and NADH is promoted so as to enhance the low temperature resistance of the system and achieve the stable nitrogen removal under the low temperature condition.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a method for sulfur autotrophic denitrification under strong low temperature. Background Art

[0002] Nitrogen pollution in water bodies has become an environmental issue of global concern. 50% of food produced by human society relies on industrial nitrogen fertilizers, which results in excessive nitrogen entering aquatic ecosystems and increases the risk of eutrophication. Wastewater treatment technologies aimed at nitrogen and phosphorus removal have become the mainstream process today. Heterotrophic denitrification is currently the most widely used biological denitrification process for wastewater. However, this process has many technical drawbacks, such as dependence on external organic carbon sources, large sludge production, and serious greenhouse gas emissions. In contrast, autotrophic denitrification processes driven by inorganic electron donors (such as sulfide, elemental sulfur, and hydrogen) have overcome these technical drawbacks to a certain extent and are a new denitrification process with broad application prospects. Among them, sulfur autotrophic denitrification (SAD) is relatively efficient, and sulfur or sulfide is inexpensive, showing great application potential in the field of industrial and municipal wastewater denitrification. The reaction process is shown in the following equation (1).

[0003]

[0004] Sulfur autotrophic denitrifying bacteria include Thiobacillus denitrificans ( Thiobacillus denitrificans ) and the strict chemoautotrophic type represented by denitrifying Paracoccus ( Paracoccus denitrifican ) are facultative autotrophic bacteria represented by the genus Thiobacillus denitrificans. Thiobacillus denitrificans is a typical sulfur-autotrophic denitrifying bacterium, with an optimal growth temperature range of 28-30°C. Studies have shown that temperature is a key environmental factor affecting the sulfur-autotrophic denitrification process. When water temperatures drop to 10-15°C, the sulfur-autotrophic denitrification rate decreases by over 80%. Therefore, addressing the issue of reduced activity of sulfur-autotrophic bacteria (groups) caused by low temperatures is crucial to promoting this efficient and sustainable biological denitrification process. Summary of the Invention

[0005] In order to solve at least one of the above problems, the present invention provides a method for enhancing the sulfur autotrophic denitrification performance at low temperature.

[0006] In order to achieve the above object, the present invention adopts the following technical means: A first aspect of the present invention provides a method for enhancing the performance of sulfur autotrophic denitrification at low temperature, comprising the following steps: S1. culturing anaerobic sludge to obtain sulfur-enriched autotrophic bacteria sludge; S2. Inoculate the sulfur autotrophic bacteria sludge enriched in the sulfur autotrophic reactor for sewage treatment. When the temperature is lower than 10-20°C, regularly add the redox couple: sodium anthraquinone-2,6-disulfonate / H2O2 into the sulfur autotrophic reactor.

[0007] In some embodiments of the present invention, in step S2, a redox couple is added, the final concentration of sodium anthraquinone-2,6-disulfonate is not less than 20 mg / L, and the amount of 30% H2O2 added is 0.05 mL / L.

[0008] In some embodiments of the present invention, the inoculation amount of the sulfur-rich autotrophic bacteria sludge in step S2 is 10-12% of the effective volume of the sulfur autotrophic reactor.

[0009] In some embodiments of the present invention, in step S2, the frequency of adding the redox couple is once every 5 days.

[0010] In some embodiments of the present invention, in step S1, the method for acclimating anaerobic sludge is as follows: anaerobic sludge and culture medium are mixed in a volume ratio of 1: (1.5-2), placed in a constant temperature culture at 25-30°C, for a cycle of three days, and after removing the supernatant, an equal amount of culture medium is added, and the acclimation culture is continued for 7-10 cycles.

[0011] In some embodiments of the present invention, the culture medium is prepared as follows: NaNO3 0.1 g / L, NaHCO3 0.5 g / L, (NH4)2SO4 0.1 g / L, KH2PO4 1.8 g / L, Na2HPO4 1.2 g / L, MgCl2·7H2O 0.1 g / L, CaCl2·2H2O 0.04 g / L, FeCl3·6H2O 0.03 g / L, and MnSO4·xH2O 0.03 g / L are taken, the preparation volume is made up with deionized water, and the mixture is sterilized by high pressure at 121°C for 15-20 minutes. After cooling, Na2S2O3 solution is added at a concentration of 100 mL / L.

[0012] In some embodiments of the present invention, the Na2S2O3 solution has a mass volume concentration of 10% and is sterilized separately after filtration.

[0013] In some embodiments of the present invention, the sulfur autotrophic reactor is loaded with 2 / 3 of its volume of sulfur autotrophic filler.

[0014] Beneficial effects of the present invention Compared with the prior art, the present invention has the following beneficial effects: redox couples play an important role in microbial metabolism and are the key to driving energy metabolism and material circulation. The present invention improves the electron transfer efficiency and the metabolic activity of the sulfur autotrophic bacteria by adding exogenous redox couples - sodium anthraquinone-2,6-disulfonate / H2O2 to the sulfur autotrophic denitrification system under low temperature conditions, promotes the synthesis of intracellular resources ATP and NADH, effectively improves the low temperature resistance of the sulfur autotrophic denitrification system, achieves stable denitrification under low temperature conditions of 10-20°C, and improves the denitrification performance of the biological denitrification process based on sulfur autotrophic denitrification under low temperature conditions of 15°C; the possible reason is that the exogenous addition of redox couples can create new electron flow pathways for microbial energy metabolism. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The NO3 content during the acclimation of sulfur-rich autotrophic sludge in Example 1 of the present invention is shown. − -N concentration change curve; Figure 2 The comparison of denitrification efficiency of the sulfur autotrophic denitrification system at different culture temperatures in Example 2 of the present invention is shown; Figure 3 The results show the enhancement effect of different redox couples on the sulfur autotrophic denitrification system under low temperature conditions of 15°C in Example 3 of the present invention; Figure 4 The results show the comparison of the denitrification enhancement effect of different anthraquinone-2,6-disulfonic acid sodium concentrations on the sulfur autotrophic denitrification system under low temperature conditions of 15°C in Example 4 of the present invention; Figure 5 The enhanced denitrification curve of the continuous sulfur autotrophic denitrification reactor of Example 5 of the present invention under low temperature conditions of 15°C is shown. DETAILED DESCRIPTION

[0016] The following examples are provided to illustrate preferred embodiments of the present invention. Those skilled in the art will appreciate that the techniques disclosed in the following examples represent techniques discovered by the inventors that can be used to practice the present invention and, therefore, can be considered preferred embodiments of the present invention. However, those skilled in the art will appreciate from this disclosure that many modifications may be made to the specific embodiments disclosed herein while still achieving the same or similar results without departing from the spirit or scope of the present invention.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention belongs, and the disclosures herein and the materials they cite are hereby incorporated by reference. Those skilled in the art will recognize or be able to ascertain, through routine experimentation, many technical equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0018] The technical solution of the present application will be further described in detail below in conjunction with specific implementation methods.

[0019] Example 1 Preparation of sulfur autotrophic bacteria sludge Take a 5 L conical flask, add 1 L of anaerobic sludge taken from the anaerobic tank of a town sewage pool factory and 1.5 L of culture medium. During the cultivation process, the bottle mouth is sealed with a rubber stopper and placed in a constant temperature incubator at 30°C for cultivation.

[0020] The composition of the culture medium is: NaNO3 0.1 g / L, NaHCO3 0.5 g / L, (NH4)2SO4 0.1 g / L, KH2PO4 1.8 g / L, Na2HPO4 1.2 g / L, MgCl2·7H2O 0.1 g / L, CaCl2·2H2O 0.04 g / L, FeCl3·6H2O 0.03 g / L, MnSO4·xH2O 0.03 g / L, and deionized water is added to 1 L. The culture medium is sterilized by high pressure at 121°C for 15 minutes. After cooling, 100 mL / L of Na2S2O3 solution with a mass volume concentration of 10% and sterilized separately by filtration is added.

[0021] The sludge acclimation time was 3 days as a cycle. After removing the supernatant, an equal amount of culture medium was added. At the same time, 5 mL of supernatant was taken every day to monitor NO 3− -N changes, continuous acclimation and cultivation for 7-10 cycles.

[0022] NO3 during sludge conditioning − -N concentration change curve is as follows Figure 1 shown.

[0023] The results showed that with the increase of acclimation time, the nitrogen removal rate in 24 hours could reach about 60%, and the nitrogen removal rate in 2-3 days could reach more than 75%, indicating that a high biomass of sulfur autotrophic bacteria was enriched in the sludge, that is, sulfur autotrophic bacteria-rich sludge was obtained.

[0024] Example 2 Comparison of denitrification effects of sulfur autotrophic denitrification system at different temperatures Take a 500 mL conical flask with a lid, and fill 100 mL of sulfur autotrophic filler (prepared in the laboratory by bonding and granulating sulfur, FeCO3 powder, white cement, nano-bentonite and other materials. Commercially available sulfur autotrophic filler can also be used) in a triangular flask. Then, add 40 mL of the sulfur autotrophic denitrification sludge domesticated in Example 1 and 200 mL of simulated wastewater. The main components of the simulated wastewater are as follows: NaNO3 0.121 g / L, Na2S2O3 1.5 g / L, NaHCO3 0.1 g / L, NH4Cl 0.002 g / L, Na2HPO4 0.15 g / L, MgCl2·7H2O 0.5 g / L, CaCl2·2H2O 0.01 g / L and 1 ml / L Wolfe's trace element solution.

[0025] The denitrification performance of the sulfur autotrophic denitrification system was tested at 15℃, 20℃, and 25℃. The supernatant was removed and supplemented with an equal amount of simulated wastewater for 3 days. The NO 3− -N changes, the denitrification efficiency comparison results at different culture temperatures are as follows Figure 2 shown.

[0026] The results showed that when the culture temperature was 15℃, the initial nitrate nitrogen decreased from 19.0, 20.1, and 19.1 mg / L to 15.0 mg / L, 11.8 mg / L, and 7.3 mg / L after 24, 48, and 72 h, with removal rates of 22.7%, 41.5%, and 61.8%, respectively. When the culture temperature was 20℃, the nitrate nitrogen removal rates were 49.0%, 61.4%, and 70.8% after 24, 48, and 72 h, respectively. When the culture temperature was 25℃, the nitrate nitrogen removal rates were 63.9%, 68.6%, and 72.2%, respectively. In summary, when the culture temperature was 15℃, the denitrification efficiency after 24, 48, and 72 h of culture was reduced by 41.2%, 27.1%, and 10.7%, respectively, compared with the nitrate nitrogen removal rate at 25℃, indicating that low temperature conditions significantly reduce the denitrification rate of sulfur autotrophic bacteria.

[0027] Example 3 Screening of different redox couples in sulfur autotrophic denitrification system Based on Example 2, four 500 mL conical flasks with lids were further prepared. After adding sulfur-based filler to the 100 mL mark, 40 mL of the sulfur autotrophic denitrification sludge domesticated in Example 1 and 200 mL of simulated wastewater were added. The flasks were sealed and placed in a 15°C incubator. The supernatant NO was monitored in two stages. 3− -N changes, compare the enhanced denitrification effects of different redox couples on sulfur autotrophic denitrification: (1) Control group: no substance was added; (2) Add fulvic acid with a final concentration of 50 mg / L and 0.05 ml / L 30% H2O2; (3) Add sodium anthraquinone-2,6-disulfonate with a final concentration of 50 mg / L + 0.05 ml / L 30% H2O2; (4) The final concentration is 50 mg / L riboflavin + 0.05 ml / L 30% H2O2; the results of the enhanced low-temperature denitrification effect are as follows Figure 3 shown.

[0028] The results showed that under low-temperature conditions of 15°C, the first seven days were spent on sludge adaptation and further acclimation. Compared with the control group, the group adding sodium anthraquinone-2,6-disulfonate / H2O2 reduced nitrate nitrogen to below 5 mg / L on the sixth day, shortening the sludge acclimation period. Subsequently, a monitoring period of three days was established. The control group had an average removal rate of 44.1%, 66.3%, and 81.4% over 24 hours, 48 ​​hours, and 72 hours, respectively. The sodium anthraquinone-2,6-disulfonate / H2O2 combination achieved the best results, with average nitrate nitrogen removal rates of 63.9%, 82.3%, and 92.3% over 24 hours, 48 ​​hours, and 72 hours, respectively, representing increases of 19.8%, 16.0%, and 10.9% over the control group.

[0029] Example 4 Dosage of Redox Electrode Substances Take five 500 mL conical flasks with stoppers, add sulfur-based filler to the 100 mL mark, add 40 mL of sulfur autotrophic denitrification sludge domesticated in Example 1 and 200 mL of simulated wastewater, seal the flasks and place them in an incubator at 15°C to monitor the supernatant NO 3− -N changes, comparing the enhanced denitrification effects of different concentrations of redox couples on sulfur autotrophic denitrification: (1) Control group: no substance was added; (2) The final concentration is 5 mg / L anthraquinone-2,6-disulfonic acid sodium + 0.05 ml / L 30% H2O2; (3) The final concentration is 10 mg / L anthraquinone-2,6-disulfonic acid sodium + 0.05 ml / L 30% H2O2; (4) The final concentration is 20 mg / L anthraquinone-2,6-disulfonic acid sodium + 0.05 ml / L 30% H2O2; (5) The final concentration is 30mg / L anthraquinone-2,6-disulfonic acid sodium + 0.05ml / L 30% H2O2, and the results of the enhanced low-temperature denitrification effect are as follows Figure 4 shown The results showed that compared with the blank control group, with the increase of the concentration of anthraquinone-2,6-disulfonic acid sodium, the denitrification efficiency of the sulfur autotrophic denitrification system under low temperature conditions gradually increased. The denitrification efficiency of the enhanced group with a final concentration of 20 mg / L anthraquinone-2,6-disulfonic acid sodium was similar to that of the 30 mg / L anthraquinone-2,6-disulfonic acid sodium. Compared with the control group, the removal efficiency of nitrate nitrogen increased by 13.8% and 14.6%, respectively. Therefore, the final concentration of anthraquinone-2,6-disulfonic acid sodium was determined to be 20 mg / L.

[0030] Example 5 Effect of Low-Temperature Enhanced Operation of Continuous Sulfur Autotrophic Reactor A continuous low-temperature denitrification test was carried out in a chromatography cabinet at 15°C. Two cylindrical reactors (φ20 cm, h 100 cm) were used. Water was fed into the bottom and discharged from the top. 2 / 3 of the volume of the sulfur autotrophic filler was loaded. One reactor was used as a control group and conventionally inoculated with the sulfur autotrophic denitrification sludge of Example 1. The other reactor was used as a low-temperature enhanced group and inoculated with the sulfur-rich autotrophic bacteria sludge cultured in Example 1. 20 mg / L sodium anthraquinone-2,6-disulfonate + 0.05 ml / L 30% H2O2 was added regularly at a frequency of 5 days / time. The sludge inoculation amount of the two reactors was about 10% of their effective volume. Simulated wastewater was pumped into the reactor by a peristaltic pump. The influent NO 3- -N concentration is 22~25 mg / L. The first 5 days are the first stage, internal circulation, and microbial biofilm formation. Continuous water inflow begins after 5 days. The middle 15 days are the second stage, with a hydraulic retention time of 24h. The last 10 days are the third stage, shortening the hydraulic retention time to 6h.

[0031] The enhanced denitrification curve of the continuous sulfur autotrophic denitrification reactor under low temperature conditions of 15℃ is as follows Figure 5 shown.

[0032] The results showed that under low temperature conditions of 15℃, the average removal rates of nitrate nitrogen in the control group at HRT=24h and HRT=6h were 42.3% and 25.0%, respectively, while the removal rates of nitrate nitrogen in the low temperature enhanced group with addition of sodium anthraquinone-2,6-disulfonate / H2O2 were 60.4% and 42.7% at HRT=24h and HRT=6h, which were 17.9% and 17.7% higher than those in the control group, respectively.

[0033] All documents mentioned in this application are incorporated herein by reference, just as if each document were incorporated herein by reference individually. It should also be understood that after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and that such equivalents also fall within the scope of the present application.

Claims

1. A method for enhancing the performance of sulfur autotrophic denitrification at low temperature, characterized in that: The steps include: S1. culturing anaerobic sludge to obtain sulfur-enriched autotrophic bacteria sludge; S2. Inoculate the sulfur autotrophic bacteria sludge enriched in the sulfur autotrophic reactor for sewage treatment. When the ambient temperature is 10-20°C, regularly add the redox couple: sodium anthraquinone-2,6-disulfonate / H2O2 into the sulfur autotrophic reactor.

2. The method for enhancing the performance of sulfur autotrophic denitrification at low temperature according to claim 1, characterized in that: In step S2, a redox couple is added, the final concentration of sodium anthraquinone-2,6-disulfonate is not less than 20 mg / L, and the amount of 30% H2O2 added is 0.05 mL / L.

3. The method for enhancing the sulfur autotrophic denitrification performance at low temperature according to claim 1, characterized in that: In step S2, the inoculation amount of the sulfur-rich autotrophic bacteria sludge is 10-12% of the effective volume of the sulfur autotrophic reactor.

4. The method for enhancing the sulfur autotrophic denitrification performance at low temperature according to claim 1, characterized in that: In step S2, the redox couple is added once every 5 days.

5. The method for enhancing the performance of sulfur autotrophic denitrification at low temperature according to claim 1, characterized in that: In step S1, the method for acclimating the anaerobic sludge is as follows: the anaerobic sludge and the culture medium are mixed in a volume ratio of 1:(1.5-2), and the mixture is cultured at a constant temperature of 25-30°C for three days. After removing the supernatant, an equal amount of culture medium is added, and the acclimation culture is continued for 7-10 cycles.

6. The method for enhancing the performance of sulfur autotrophic denitrification at low temperature according to claim 5, characterized in that: The culture medium is prepared by taking the following amounts: NaNO3 0.1 g / L, NaHCO3 0.5 g / L, (NH4)2SO4 0.1 g / L, KH2PO4 1.8 g / L, Na2HPO4 1.2 g / L, MgCl2·7H2O 0.1 g / L, CaCl2·2H2O 0.04 g / L, FeCl3·6H2O 0.03 g / L, and MnSO4·xH2O 0.03 g / L, making up the preparation volume with deionized water, sterilizing under high pressure at 121° C. for 15-20 minutes, and adding Na2S2O3 solution to a concentration of 100 mL / L after cooling.

7. The method for enhancing the sulfur autotrophic denitrification performance at low temperature according to claim 6, characterized in that: The mass volume concentration of the Na2S2O3 solution is 10%, and it is sterilized separately after filtration.

8. The method for enhancing the performance of sulfur autotrophic denitrification at low temperature according to claim 1, characterized in that: The sulfur autotrophic reactor is loaded with 2 / 3 of its volume of sulfur autotrophic filler.

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