CN113800651A

CN113800651A - A method for fast start-up of anammox reactor by immobilization of anammox microorganisms

Info

Publication number: CN113800651A
Application number: CN202111244920.4A
Authority: CN
Inventors: 胡真虎; 李仲轩; 唐睿; 王伟; 袁守军; 俞汉青; 占新民; 阿蓉; 苏馈足
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2021-12-17

Abstract

The invention discloses a method for realizing the quick start of an anammox reactor by fixing anammox microorganisms, which comprises the steps of firstly dissolving a gel material in a solvent at high temperature and high pressure, and changing the property and the structure of the material by ultrasonic treatment; then, uniformly mixing the microorganisms and the modified gel material, and forming porous gel particle pellets, namely anaerobic ammonium oxidation bacteria immobilized gel beads, by a physical and chemical means; anaerobic ammonium oxidation bacteria immobilized gel beads are inoculated in a continuous stirred reactor CSTR, and the anaerobic ammonium oxidation reactor is quickly started under a proper culture condition. According to the invention, a small amount of anammox bacteria is used for realizing the rapid start of the anammox reactor in a gel fixing mode, so that the actual demand of the anammox bacteria is reduced; meanwhile, the gel immobilized material obtains higher mass transfer capacity and pore structure, and guarantees the growth, enrichment and stable operation of the anaerobic ammonium oxidation bacteria.

Description

Method for realizing rapid start of anaerobic ammonia oxidation reactor through immobilization of anaerobic ammonia oxidation microorganisms

Technical Field

The invention relates to a method for realizing quick start of an anaerobic ammonia oxidation reactor by fixing anaerobic ammonia oxidation microorganisms, belonging to the technical field of biological denitrification of wastewater.

Background

Compared with the traditional nitrification-denitrification technology, the anaerobic ammonia oxidation denitrification technology has the advantages of small floor area, low energy consumption, no additional carbon source, less generated residual sludge and the like. The anaerobic ammonium oxidation bacteria is an anaerobic autotrophic microorganism, the generation proliferation period is about 11-17d, and the growth speed is slow; meanwhile, the anaerobic ammonia oxidation granular sludge is easy to wash out from the reactor due to the formation of air bags inside the anaerobic ammonia oxidation granular sludge, so that the problem of easy loss of the anaerobic ammonia oxidation granular sludge is caused, the starting duration of the anaerobic ammonia oxidation reactor is very long, and the application of the anaerobic ammonia oxidation technology in sewage treatment is limited. How to realize the quick start of the reactor for inoculating the low-concentration anaerobic ammonium oxidation bacteria and improve the biological activity of the anaerobic ammonium oxidation bacteria is the key of the quick start and operation of the anaerobic ammonium oxidation reactor.

The microbial immobilization technology is a novel technology for immobilizing microorganisms in a limited spatial region by a chemical or physical method so that the microorganisms can maintain biological activity and can be reused, and the main methods thereof include an adsorption method, an embedding method and a crosslinking method. The embedding method is a microorganism fixing method in which microorganisms are embedded in various gel grids and films, so that the microorganisms are confined in a limited space and substrates can freely enter. The treatment can avoid the loss of low-concentration anammox bacteria, provide a good microenvironment for the culture and enrichment of the anammox bacteria, quickly improve the thallus concentration of the anammox bacteria in a reactor system, effectively increase the retention rate and the cell density of the anammox bacteria, and realize the quick start and the stable operation of the anammox reactor.

Disclosure of Invention

The invention mainly aims to provide a method for realizing the quick start of an anaerobic ammonia oxidation reactor by fixing anaerobic ammonia oxidation microorganisms, which can effectively solve the bottleneck problem in the background technology.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention relates to a method for realizing the quick start of an anaerobic ammonia oxidation reactor by fixing anaerobic ammonia oxidation microorganisms, which comprises the steps of firstly dissolving a gel material in a solvent at high temperature and high pressure, and changing the property and the structure of the material by ultrasonic treatment; then, uniformly mixing the microorganisms and the modified gel material, and forming porous gel particle pellets (anaerobic ammonium oxidation bacteria immobilized gel beads) by a physical and chemical means; anaerobic ammonium oxidation bacteria immobilized gel beads are inoculated in a continuous stirred reactor (CSTR), and the anaerobic ammonium oxidation reactor is quickly started under proper culture conditions.

The method specifically comprises the following steps:

step 1: preparation of immobilized gel beads

1a, dissolving polyvinyl alcohol (PVA) and Sodium Alginate (SA) into an aqueous solution, and treating for 10-15 min under the conditions of high temperature and high pressure to obtain a PVA-SA gel solution, wherein the final concentration of the PVA in the gel solution is 15% -30%, and the final concentration of the SA is 1% -4%; then adding 1-3% of activated carbon particles and 1-3% of nano ferroferric oxide (based on the PVA-SA gel solution) into the PVA-SA gel solution, uniformly stirring, and modifying the gel material by ultrasonic treatment;

1b, under the protection of nitrogen, crushing anaerobic ammonia oxidation granular sludge (VSS is 3-5 gVSS/L) with the grain size of 1-3 mm into flocculent sludge with the grain size of 50-100 mu m by using a tissue homogenizer, then carrying out isovolumetric homogeneous mixing on the flocculent sludge and the modified gel solution obtained in the step 1a, and adding 1-4% of potassium bicarbonate or sodium bicarbonate (based on the total volume of the gel mixed sludge); under the protection of nitrogen, the bacterial liquid mixture is dripped into a mixed solution containing 4-6% of boric acid and 3-6% of calcium chloride by a peristaltic pump to carry out a crosslinking reaction, and finally the mixed solution is placed at 4 ℃ for solidification and molding to obtain gel beads.

And 1c, placing the gel beads obtained in the step 1b in 0.3-0.5M phosphate solution for phosphorylation treatment, so that the mechanical strength of the gel beads is enhanced while phosphorylation is carried out.

In order to enhance the strength of the gel beads, a chemical double crosslinking and freezing crosslinking method is adopted in the step.

Step 2: rapid start-up of anammox reactors

And (3) putting the gel beads after the microorganisms are fixed in the step (1) into an anaerobic ammonia oxidation CSTR reactor for operation according to a certain filling ratio.

In the step 1a, the high temperature and the high pressure refer to the conditions of the temperature of 90-121 ℃ and the pressure of 0.1-0.2 MPa.

In the step 1a, the temperature during ultrasonic treatment is 40-60 ℃, the ultrasonic power is 100-150W, and the ultrasonic time is 30-60 min.

In the step 1c, the phosphate solution is potassium dihydrogen phosphate solution, and the phosphorylation treatment time is controlled to be 40-90 min.

In the step 2, the anaerobic ammonia oxidation device is a 2L CSTR reactor, and the height-diameter ratio of the reactor is 3: 1.

In the step 2, the filling rate of the gel beads is 20-25% of the volume of the reactor.

In the step 2, in the operation process of the CSTR reactor, the hydraulic retention time is 1 day, the reaction temperature is 30-35 ℃, and the reaction pH is controlled to be 7.8-8.5.

In the step 2, pre-aeration nitrogen treatment is carried out on inlet water of the CSTR reactor for 15-20 min to remove dissolved oxygen in the inlet water and control the dissolved oxygen to be below 0.2 mg/L; and ammonia nitrogen, nitrite nitrogen, nutrient substances and trace elements are added into the intake water to provide nutrient conditions required by the growth of the anaerobic ammonium oxidation bacteria. The reactor is pumped into the bottom of the reactor, and the reaction solution in the reactor is fully and uniformly mixed in a magnetic stirring mode. The water outlet is arranged at the position of the liquid level and is discharged by the pump.

The specific contents of the ammonia nitrogen and the nitrite nitrogen are added according to the embodiment, and the specific contents of the nutrient elements are shown in the table below.

The ammonia nitrogen and nitrite nitrogen concentration and the activity of the anaerobic ammonia oxidation bacteria are monitored, the ammonia nitrogen and nitrate nitrogen concentration of the inlet water of the reactor are adjusted according to the outlet water parameters along with the increase of the activity, the anaerobic ammonia oxidation reactor can be successfully started in about one month in the experimental process, and the starting time of the anaerobic ammonia oxidation reactor is remarkably shortened.

The invention has the beneficial effects that:

the invention overcomes the defect that the anaerobic ammonia oxidation granulation is easy to run off, realizes the quick start of the anaerobic ammonia oxidation reactor by using a small amount of anaerobic ammonia oxidation bacteria in a gel fixing mode, and reduces the actual required amount of the anaerobic ammonia oxidation bacteria; meanwhile, the gel immobilized material obtains higher mass transfer capacity and pore structure, and guarantees the growth, enrichment and stable operation of the anaerobic ammonium oxidation bacteria.

Drawings

FIG. 1 is a flow chart of the process for preparing the gel beads of the present invention.

FIG. 2 is a schematic diagram of the configuration of an anammox CSTR reactor. Wherein: 1 water distribution barrel, 2 water inlet pumps, 3 anaerobic ammonia oxidation reactors, 4 magnetic stirrers, 5 temperature controllers, 6 water outlet pumps and 7 water outlet barrels.

FIG. 3 is a photograph of gel-immobilized anammox bacteria.

FIG. 4 shows the change of ammonia nitrogen and nitrite nitrogen in the starting process of the CSTR reactor, i.e., the relationship between the concentration of each substance in the inlet and outlet water and the reaction time.

FIG. 5 is a graph showing the relationship between the removal rate of ammonia nitrogen and nitrite nitrogen and the reaction time during the start-up of a CSTR reactor.

FIG. 6 is a schematic view of the ASBR reactor apparatus. Wherein: 1 water distribution barrel, 2 water inlet pumps, 3 anaerobic ammonia oxidation reactors, 4 mechanical stirrers, 5 temperature controllers, 6pH controllers, 7 water outlet pumps and 8 water outlet barrels.

FIG. 7 is the change of ammonia nitrogen and nitrite nitrogen in the starting process of 4 SBR reactors, namely the relation between the concentration of each substance in inlet and outlet water and the reaction time. Wherein (1) 0.8g of VSS anaerobic ammonia oxidation sludge is fixed; (2) fixing 1.2g of VSS anaerobic ammonia oxidation sludge; (3) fixing 1.6g of VSS anaerobic ammonia oxidation sludge; (4) 2g of VSS anammox sludge was fixed.

Detailed Description

The technical scheme of the invention is further analyzed and explained by combining specific examples.

Example 1: selection of the proportion of immobilized gel materials

The embodiment provides a method for determining the proportion of immobilized gel bead materials, which comprises the following specific steps:

1. dissolving polyvinyl alcohol (PVA) and Sodium Alginate (SA) in an aqueous solution, and treating for 15min at the temperature of 121 ℃ and the pressure of 0.12MPa to obtain a PVA-SA gel solution, wherein the specific gel bead material ratio is shown in the following table:

2. mixing the gel bead solution and distilled water in equal volume; and dripping the bacteria liquid mixture into a mixed solution containing 6 percent of boric acid and 4 percent of calcium chloride at the rotating speed of 1rpm/min through a peristaltic pump to perform a crosslinking reaction.

3. The gel material obtained in 1b was treated in 0.5M potassium dihydrogen phosphate solution for 1 hour to phosphorylate it, washed with distilled water until the water was free from foam, and then placed in a refrigerator at 4 ℃ for one week.

4. Adding gel beads with different proportions into a beaker, wherein the filling rate is about 25 percent, and the gel beads are operated for 30 days under the action of magnetic stirring, and the rotating speed of the magnetic stirring is 200 rpm.

The stability of the gel bead structure at the end of the reaction was observed. Slightly softened (+); slightly softer, less elastic (++); softening, poor elasticity (+++); loose structure, brittle (+++).

Example 2: preparation of immobilized gel beads

As shown in fig. 1. The embodiment provides a preparation method of anaerobic ammonium oxidation bacteria immobilized gel beads, which comprises the following specific steps:

1. dissolving polyvinyl alcohol (PVA) and Sodium Alginate (SA) in an aqueous solution, and treating for 15min at the temperature of 121 ℃ and the pressure of 0.12MPa to obtain a PVA-SA gel solution, wherein the final concentration of PVA and SA in the gel solution is 25% and 3%; then adding 1% of activated carbon particles and 2% of nano-scale ferroferric oxide (the addition amount of the activated carbon and the nano-scale ferroferric oxide is calculated by the volume of the gel solution) into the PVA-SA gel solution, uniformly stirring, and modifying the gel material by ultrasonic treatment; the ultrasonic treatment temperature is 50 ℃, the ultrasonic power is 140W, and the ultrasonic time is 30 min.

2. Under the protection of nitrogen, crushing anaerobic ammonia oxidation granular sludge (VSS is 4g/L) with the particle size of 1-3 mm into flocculent sludge with the particle size of 50 mu m by using a tissue homogenizer, then mixing the flocculent sludge with the modified gel solution obtained in the step 1a in an isovolumetric homogenizing way, and adding 2% of sodium bicarbonate (based on the total volume of the sludge mixed gel); under the protection of nitrogen, the bacterial liquid mixture is dripped into a mixed solution containing 6 percent of boric acid and 4 percent of calcium chloride by a peristaltic pump at the rotating speed of 1rpm/min to generate a crosslinking reaction.

3. The gel material obtained in 1b was treated in 0.5M potassium dihydrogen phosphate solution for 1 hour to phosphorylate it, washed with distilled water until the water was free from foam, and then placed in a refrigerator at 4 ℃ for one week. The prepared gel beads for immobilizing anammox bacteria are shown in FIG. 3.

Example 3: rapid start-up of anammox reactors

The schematic diagram of the anaerobic ammonia oxidation CSTR reactor device is shown in figure 2. This example provides a method for rapid start-up of an anammox reactor, comprising the following steps

1. The anaerobic ammonia oxidation device is a 2L CSTR reactor, the height-diameter ratio of the reactor is 3:1, the gel beads immobilized by the anaerobic ammonia oxidizing bacteria prepared in the example 1 are added into the reactor, and the filling rate is about one quarter of the volume of the reactor, namely 25%; in the reaction process, the reaction temperature is controlled to be 30-35 ℃, the reaction pH is controlled to be 7.8-8.5, and the hydraulic retention time is 1 day.

2. In the water inlet of the reactor, removing dissolved oxygen in the water inlet by aerating nitrogen for 15min, and controlling the dissolved oxygen to be below 0.2 mg/L; and adding ammonia nitrogen, nitrite nitrogen, nutrient substances and trace elements into the intake water, and providing nutrient conditions required by the growth of anaerobic ammonia oxidation bacteria, wherein a nutrient solution is added into the anaerobic ammonia oxidation intake water, and the trace element components in the nutrient solution and the specific adding concentration in the intake water are shown in the step 2. And the reaction solution in the reactor is fully and uniformly mixed in a magnetic stirring mode.

3. Pumping the reactor inlet water into the bottom of the reactor to mix the inlet water with the reaction solution; the water outlet is arranged at the position of the liquid level and is discharged by the pump.

4. The anaerobic ammonia oxidation starting process is divided into two stages: stage I, NH₄ ⁺N concentration of 30mg/L, NO₂ ^--N concentration 40 mg/L; stage II, NH₄ ⁺N concentration 50mg/L, NO₂ ^-The concentration of N was 70 mg/L. Nutrient solution is added into the anaerobic ammonia oxidation inlet water, and the trace element components in the nutrient solution and the specific adding concentration in the inlet water are as shown in example 1:

the ammonia nitrogen and nitrite nitrogen concentration and the activity of the anaerobic ammonia oxidation bacteria are monitored in the operation process, the ammonia nitrogen and nitrite nitrogen concentration in the inlet water is gradually adjusted along with the increase of the activity, the anaerobic ammonia oxidation reactor can be successfully started in about one month in the experimental process, and the starting time of the anaerobic ammonia oxidation reactor is remarkably shortened. The trinitrogen variation and nitrogen removal during the start-up of the CSTR reactor is shown in fig. 4, fig. 5.

Example 4: selection of fixed anammox sludge concentration

A schematic of the ASBR reactor apparatus used in this example is shown in fig. 6. This example provides a method for starting an anammox reactor using anammox bacteria with low biomass concentration, which comprises the following steps

1. Gel beads in which different concentrations of anammox sludge biomass were immobilized were prepared in 4 as in example 3, and each gel bead was designated as gel bead 1 (anammox sludge with 0.8g of VSS immobilized); gel beads 2 (anaerobic ammonium oxidation sludge with VSS of 1.2g immobilized); gel beads 3 (anaerobic ammonium oxidation sludge with VSS of 1.6g immobilized); gel beads 4 (anaerobic ammonium oxidation sludge with VSS of 2.0g fixed).

2. The anaerobic ammonia oxidation device is 4 ASBR reactors with 4L, the height-diameter ratio of the reactors is 6:1, 4 gel beads prepared in the step 1 are respectively added into the 4 reactors, and the filling rate is about one fourth of the volume of the reactors, namely 25%; in the reaction process, the reaction temperature is controlled to be 30-35 ℃, the reaction pH is controlled to be 7.8-8.5, the water filling ratio is 0.5, and the hydraulic retention time is 1 day.

3. Pumping the feed water into the bottom of the SBR reactor to mix the feed water with the reaction solution; the water outlet is arranged at one half of the reactor and is discharged by a pump.

4. The anaerobic ammonia oxidation starting process is divided into three stages: stage I, NH₄ ⁺N concentration of 30mg/L, NO₂ ^--N concentration 40 mg/L; stage II, NH₄ ⁺N concentration 50mg/L, NO₂ ^--N concentration 70 mg/L; stage II, NH₄ ⁺N concentration of 100mg/L, NO₂ ^--a concentration of 130mg/L of N; and (3) adding a nutrient solution into the anaerobic ammonia oxidation inlet water, wherein the trace element components in the nutrient solution and the specific adding concentration in the inlet water are shown in the step 2.

And monitoring the ammonia nitrogen and nitrite nitrogen concentration and the activity of anaerobic ammonium oxidation bacteria in the operation process, gradually adjusting the ammonia nitrogen and nitrite nitrogen concentration in the inlet water along with the increase of the activity, and performing the whole experiment process for 40 days. The experimental results show that the anaerobic ammoxidation reactor can be successfully started about 30 days after the ASBR reactor which is inoculated with 0.3 gVSS/L. The trinitrogen shift during the start-up of the ASBR reactor is shown in fig. 7.

The foregoing describes exemplary embodiments of the present invention by way of illustration only, and modifications of the described embodiments in various ways will be apparent to those of ordinary skill in the art without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting the scope of the invention.

Claims

1. a method for realizing the quick start of anammox reactor by the fixation of anammox microorganism, is characterized in that:

First, the gel material is dissolved in a solvent through high temperature and high pressure, and the properties and structure of the material are changed by ultrasonic treatment; then the microorganisms and the modified gel material are homogeneously mixed to form porous gel particle spheres by physical and chemical means—— The anammox bacteria immobilized gel beads; the anammox bacteria immobilized gel beads were inoculated in the continuous stirring reactor CSTR, and the rapid start-up of the anammox reactor was realized under suitable culture conditions.

2. method according to claim 1 is characterized in that comprising the steps:

Step 1: Preparation of Immobilized Gel Beads

1a. Dissolve polyvinyl alcohol and sodium alginate into an aqueous solution, and treat under high temperature and high pressure for 10 to 15 minutes to obtain a PVA-SA gel solution; then add activated carbon particles and nano-scale tetroxide to the PVA-SA gel solution Three iron, stir evenly, and modify the gel material by ultrasonic treatment;

1b. Under the protection of nitrogen, the anaerobic ammonia oxidation granular sludge with a particle size of 1 to 3 mm is broken into flocculent sludge with a particle size of 50 to 100 μm by a tissue homogenizer, and then mixed with the modified gel obtained in 1a. The solution is mixed homogeneously in equal volume, and 1% to 4% of potassium bicarbonate or sodium bicarbonate is added; under nitrogen protection, the bacterial liquid mixture is dropped into 4% to 6% of boric acid and 3% to 6% of boric acid through a peristaltic pump. The cross-linking reaction occurs in the mixed solution of % calcium chloride, and finally it is solidified and formed at 4 °C to obtain gel beads;

1c. The gel beads obtained in 1b are placed in a 0.3-0.5M phosphate solution for phosphorylation, so as to phosphorylate and enhance their mechanical strength;

Step 2: Rapid Start-up of the Anammox Reactor

The gel beads after immobilizing the microorganisms in step 1 were put into the anammox CSTR reactor at a certain filling ratio for operation.

3. method according to claim 2, is characterized in that:

In step 1a, the high temperature and high pressure refers to the conditions of a temperature of 90-121° C. and a pressure of 0.1-0.2 MPa.

4. method according to claim 2, is characterized in that:

In step 1a, the final concentration of PVA in the PVA-SA gel solution is 15% to 30%, and the final concentration of SA is 1% to 4%; the added amount of activated carbon particles is 1% to 1% of the mass of the PVA-SA gel solution. 3%, and the addition amount of nano-scale ferric oxide is 1% to 3% of the mass of the PVA-SA gel solution.

5. method according to claim 2, is characterized in that:

In step 1c, the phosphate solution is potassium dihydrogen phosphate solution, and the phosphorylation treatment time is controlled within 40-90 min.

6. The method according to claim 2, wherein:

In step 2, the filling rate of the gel beads is 20-25% of the volume of the reactor.

7. The method according to claim 2, wherein:

In step 2, the influent of the CSTR reactor is pre-treated with nitrogen for 15-20 minutes to remove the dissolved oxygen in the influent, and the dissolved oxygen is controlled below 0.2 mg/L; and ammonia nitrogen and nitrite nitrogen are added to the influent. , nutrients and trace elements to provide the nutrient conditions required for the growth of anammox bacteria.

8. The method according to claim 2, wherein:

In step 2, during the operation of the CSTR reactor, the hydraulic retention time is 1 day, the reaction temperature is 30-35°C, and the reaction pH is controlled at 7.8-8.5.