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CN-121991874-A - Screening method of low-temperature nitrifying bacteria group

CN121991874ACN 121991874 ACN121991874 ACN 121991874ACN-121991874-A

Abstract

The invention discloses a screening method of a low-temperature nitrifying flora, which comprises the following steps of performing gradient low-temperature domestication culture on activated sludge containing the nitrifying flora by using a liquid screening culture medium to obtain the low-temperature nitrifying flora, wherein the liquid screening culture medium comprises a core nitrogen source, an inorganic carbon source, basic inorganic salt, a synergistic component and a microelement mixed solution, and the synergistic component comprises spermidine, betaine, L-proline, humic acid and a vitamin B complex. According to the invention, by improving the components of the culture medium and combining gradient low-temperature domestication, the nitrifying bacteria group with strong low-temperature stability is obtained, the enrichment period of the nitrifying bacteria group with low temperature is shortened, the constructed bacteria group has strong adaptability and restoring force to temperature fluctuation, and stable denitrification efficiency can be maintained in a complex and changeable actual sewage treatment environment.

Inventors

  • ZHANG NAN
  • SUN XIUYUE
  • ZHU DAN
  • ZOU XI

Assignees

  • 中持(江苏)环境建设有限公司

Dates

Publication Date
20260508
Application Date
20260130

Claims (9)

  1. 1. A screening method of a low-temperature nitrifying bacteria group is characterized by comprising the following specific steps: Performing gradient low-temperature domestication culture on the activated sludge containing nitrifying bacteria groups by using a liquid screening culture medium to obtain low-temperature nitrifying bacteria groups; the liquid screening culture medium comprises a core nitrogen source, an inorganic carbon source, basic inorganic salt, a synergistic component and trace element mixed solution; the synergistic component comprises spermidine, betaine, L-proline, humic acid and vitamin B complex.
  2. 2. The method for screening a low-temperature nitrifying bacteria group according to claim 1, wherein the mass ratio of the spermidine to the betaine to the L-proline to the humic acid to the vitamin B complex is (1-3): (10-20): (5-10): (8-12): (0.5-1).
  3. 3. The method for screening a low-temperature nitrifying bacteria group according to claim 1, wherein said liquid screening medium comprises the following components in the following amounts per 1000 mL distilled water: the core nitrogen source is 0.5-1.5 g of ammonium chloride and 0.2-0.6 g of ammonium sulfate; inorganic carbon source is sodium bicarbonate 1.5-2.1 g, sodium carbonate 0.2-0.3 g; basic inorganic salt ：KH 2 PO 4 0.1-0.2 g、K 2 HPO 4 0.3-0.4 g、MgSO 4 ·7H 2 O 0.2-0.3 g、CaCl 2 0.05-0.1 g、NaCl 1.5-2.5 g; Synergistic components of spermidine 0.01-0.03 g, betaine 0.1-0.2 g, L-proline 0.05-0.1 g, humic acid 0.08-0.12 g and vitamin B complex 0.005-0.01 g; the microelement mixture solution comprises 0.5-1.5 mL of ferrous sulfate, manganese sulfate, sodium molybdate and zinc sulfate.
  4. 4. The method for screening a low-temperature nitrifying bacterial group according to claim 1, wherein said gradient low-temperature domestication culture specifically comprises the steps of: (1) First round of domestication, transferring the enrichment solution into fresh liquid culture medium according to 10% of inoculation amount, performing aerobic culture at 15-16deg.C for 6-8 days; (2) The second round of domestication, namely transferring qualified bacterial liquid subjected to the first round of domestication according to 10% of inoculum size, performing aerobic culture at 10-12 ℃ for 7-9 days; (3) And thirdly, the temperature is reduced to 5-8 ℃, the ammonia nitrogen concentration in the culture medium is increased to 1.5-2.0 g/L, aerobic culture is carried out, the culture is carried out for 8-10 days, and the low-temperature domestication is completed.
  5. 5. The method according to claim 4, wherein the gradient cryo-tamed culture step is preceded by an initial enrichment culture step: inoculating the activated sludge into a liquid screening culture medium, and performing aerobic culture at 20-22 ℃ for 5-7 days to complete first-round enrichment to obtain an enrichment liquid.
  6. 6. The screening method of claim 1, wherein the gradient cryo-tamed culturing step is followed by a purification enrichment culturing step: transferring qualified domesticated bacterial liquid into a liquid screening culture medium, stably culturing at 5-8 ℃, and obtaining a high-efficiency low-temperature nitrifying bacteria pure culture after 2-3 rounds of transfer.
  7. 7. The screening method of claim 6, wherein the method is operated using a continuous flow reactor apparatus throughout and implements threshold triggered flow increase control based on ammonia nitrogen removal rate: In the gradient low-temperature domestication culture process, the ammonia nitrogen removal rate of the effluent is monitored in real time, when the ammonia nitrogen removal rate is more than or equal to 90% and is maintained stable for 24-72 hours, the water inlet flow rate is increased according to 10% -30% of amplification, and when the ammonia nitrogen removal rate is less than 70%, the flow rate is reduced and the stabilizing time is prolonged.
  8. 8. The screening method according to claim 1, wherein the dissolved oxygen concentration in the gradient low-temperature domestication culture process is 2-3 mg/L, the stirring speed is 120-150 r/min, and the pH is 7.5-8.2.
  9. 9. Use of a low temperature nitrifying bacteria population obtained by the screening method according to any one of claims 1-8 in a biological denitrification system for wastewater treatment at 8-15 ℃.

Description

Screening method of low-temperature nitrifying bacteria group Technical Field The invention relates to the technical field of flora culture, in particular to a screening method of low-temperature nitrifying bacteria. Background Along with the increasing of the environmental protection standard of water bodies in China, the sewage discharge standard, especially the discharge limit of ammonia nitrogen, is more and more strict. The biological denitrification process has become a mainstream technology for sewage treatment due to the characteristics of economy, high efficiency and environmental friendliness. Among them, the nitrification process, which is a key step of biological denitrification, relies on Ammonia Oxidizing Bacteria (AOB) and Nitrite Oxidizing Bacteria (NOB) to convert ammonia nitrogen into nitrate. However, in winter or in northern areas of China, sewage treatment plants are generally challenged to reduce the water temperature to 8-15 ℃ or even lower. Under the low temperature condition, the metabolic enzyme activity of the traditional nitrifying bacteria group is obviously inhibited, the cell membrane fluidity is reduced, the proliferation rate is slowed down, and the efficiency of the whole nitrifying process is drastically reduced. In the prior art, the ammoxidation load of a nitration system at a low temperature is generally lower than 30 mg/(L.d), and the requirement of high-efficiency denitrification can not be met. To maintain the effluent quality to reach the standard, conventional operations often rely on external heating to raise the water temperature, or compensate for the lack of activity by extending the hydraulic retention time, increasing the sludge concentration, and the like. The methods not only greatly increase the energy consumption and the operation cost of the system, but also lead to the increase of the occupied area of the reactor, and still have difficulty in ensuring the stable operation under the frequent fluctuation of temperature, which has become a common technical bottleneck for restricting the stable standard-reaching operation of sewage treatment plants in cold areas. Aiming at the bottleneck, the prior art mainly seeks to break through from two aspects, namely, firstly, obtaining low-temperature-resistant microorganism strains through screening and domestication, and secondly, optimizing the reactor process and the operation condition. In the aspect of strain screening, the conventional method focuses on long-term domestication at a constant lower temperature, but the conventional low-temperature domestication method has obvious defects that firstly, the domestication period is long, more than 90 days are usually needed, the efficiency is low, secondly, the domestication process is mainly carried out in batch shake flasks, the obtained flora has poor adaptability to a common continuous flow operation mode and a biofilm attachment growth mode in engineering, the laboratory performance is difficult to directly convert into engineering efficiency, furthermore, the domestication condition is single, the flora has weak adaptability and recovery capability to temperature fluctuation, and when the temperature fluctuation exceeds 5 ℃, the activity of the flora is easily reduced obviously by more than 30%, and the shock load resistance of the system is insufficient. In the process level, although research is attempted to combine means such as carrier biomembrane, pH/dissolved oxygen control and the like, the integrated design which is cooperated with a specific low-temperature strain screening method is often lacked, so that strain-carrier-process-control links are disjointed, and the nitrifying load and the running stability at low temperature cannot be systematically improved. Therefore, a low-temperature nitrifying bacteria group which has high activity, strong stability and high adaptation with engineering operation conditions can be rapidly screened out, a technical scheme matched with a high-efficiency application process is formed, and the method has urgent practical significance and important application value for solving the problem of low-temperature sewage treatment. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a screening method of low-temperature nitrifying bacteria groups, which is characterized in that nitrifying bacteria groups with strong low-temperature stability are obtained by improving culture medium components and combining gradient low-temperature domestication, the enrichment period of the low-temperature nitrifying bacteria is shortened, the constructed bacteria groups have strong adaptability and restoring force to temperature fluctuation, and stable denitrification efficiency can be maintained in complex and changeable actual sewage treatment environments. In order to achieve the above object, the present invention adopts the following technical scheme: a screening method of a low-temper