Co-enrichment method of nitrifying bacteria and denitrifying phosphorus accumulating bacteria
Technical Field
The invention belongs to the technical field of biology, and particularly relates to a method for jointly enriching nitrifying bacteria and denitrifying phosphorus accumulating bacteria.
Background
The traditional biological nitrogen and phosphorus removal of sewage mainly depends on nitrification and fine removalBacteria, denitrifying bacteria, phosphorus accumulating bacteria, etc. Wherein the nitrifying bacteria belong to aerobic autotrophic microorganisms, and mainly have the functions of oxidizing ammonia into nitrite and nitrate, obtaining energy from the process of oxidizing ammonia and nitrite under the condition of sufficient nutrient supply and further assimilating CO2And the growth is slow, the generation time is long, and the growth process is easily influenced by various factors such as substrate concentration, Dissolved Oxygen (DO) concentration, pH and the like, so that the proliferation speed is slow, the rapid culture is not easy, and the industrial large-scale application is difficult. Denitrifying bacteria are mostly heterotrophic facultative bacteria that convert nitrate to nitrogen. The phosphorus accumulating bacteria are heterotrophic microorganisms, and phosphorus in sewage is absorbed into bacteria mainly by means of the fact that the aerobic phosphorus uptake during growth and proliferation is larger than the phosphorus release during the anaerobic process, so phosphorus removal can be achieved by discharging phosphorus-containing excess sludge.
In the traditional biological nitrogen and phosphorus removal process, because of the difference among microorganisms, the stability of system operation and the high-efficiency removal of pollutants are difficult to realize in the same reactor, so that in order to achieve a better removal effect, microorganisms with different functions are mostly placed in different reactors, and the system has a long process, many structures and complex operation management. For example, CN201710146749.0 discloses a biological filter for anaerobic ammonia oxidation coupled denitrification dephosphorization and an operation method thereof. CN201710269314.5 discloses a denitrification dephosphorization series-connection integrated anaerobic ammonia oxidation sewage treatment device and a method. CN201510393569.3 discloses a method for SBR partial denitrification dephosphorization/anaerobic ammonia oxidation synchronous denitrification dephosphorization. Each microorganism involved in the above method acts in a separate reactor, and the operation management is complicated.
With the continuous and deep research on sewage treatment, novel nitrogen and phosphorus removal processes and related microorganisms are developed and applied. Particularly, the denitrifying phosphorus removal process enables two independent processes of phosphorus removal and denitrification to be completed simultaneously in an anoxic environment with the participation of denitrifying phosphorus removal bacteria (DPB), the combination of the processes of phosphorus absorption and nitrogen removal not only saves the requirement on a carbon source, but also saves the energy required by aeration when the phosphorus absorption is completed in the anoxic environment, and the amount of generated residual sludge is also greatly reduced. However, the existing sewage treatment system completes biological phosphorus removal by sludge discharge, the sludge discharge reduces the number of nitrobacteria, and the nitrification effect is poor, so that the risk of substandard effluent ammonia nitrogen exists during phosphorus removal, and carbon source competition exists between denitrifying bacteria and phosphorus accumulating bacteria.
CN201510467975.X discloses a denitrification synchronous denitrification dephosphorization bacteria enrichment domestication method. The method adopts a strategy of a circulating operation mode of two-stage (firstly anaerobic/aerobic and secondly anaerobic/anoxic) enrichment domestication, firstly high and secondly low water inlet nutrition load, water inlet, reaction, precipitation and drainage, the method enhances the enrichment quantity of phosphorus-removing microorganisms, improves the microorganism propagation rate, creates the optimal condition for microorganism propagation, can enrich and domesticate denitrification synchronous denitrification phosphorus removal bacteria in a low-temperature environment through 40d anaerobic/aerobic operation and 30d anaerobic/anoxic operation, and the phosphorus concentration in the effluent is stable at 0.5 mg/L. However, only denitrifying phosphorus removal bacteria exist in the flora enriched by the method, and the application of the method to the denitrification and phosphorus removal of wastewater containing ammonia nitrogen pollutants is limited.
CN200910082222.1 discloses a method for culturing aerobic granular sludge for simultaneous denitrification and dephosphorization of domestic sewage at normal and low temperature. The method adopts two settling time modes, and in the biochemical reaction process, the dissolved oxygen concentration DO, the oxidation-reduction potential ORP and the pH value are used as real-time control parameters, and the stirring time and the aeration time are controlled in real time to obtain the aerobic granular sludge capable of simultaneously removing nitrogen and phosphorus at normal and low temperature. The method cultures thalli from the aspect of process regulation, and the number distribution, the overall activity and the adaptability of the thalli are still to be further improved.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for jointly enriching nitrifying bacteria and denitrifying phosphorus accumulating bacteria. The nitrifying bacteria and the denitrifying phosphorus accumulating bacteria obtained by the method have high activity, good synergistic effect and strong adaptability, can be cultured on site and used on site, and are particularly suitable for solving the problem that the total nitrogen and the total phosphorus of the existing sewage treatment plant do not reach the standard.
The invention provides a method for jointly enriching nitrifying bacteria and denitrifying phosphorus accumulating bacteria, which comprises the following steps:
(1) nitrifying bacteria culture stage: inoculating activated sludge containing nitrobacteria and denitrifying phosphorus accumulating bacteria, adding a culture solution, culturing the nitrobacteria under the aerobic aeration condition, and stopping aeration and starting stirring when the ammonia nitrogen concentration in the culture solution is reduced to be below 40%, preferably 10% -20% of the initial concentration;
(2) and (3) a denitrifying phosphorus accumulating bacterium culture stage: adding sugar ester substances into the culture solution obtained in the step (1), adding quaternary ammonium hydroxide after the dissolved oxygen is reduced to be less than 0.1mg/L, culturing denitrifying phosphorus bacteria, stopping stirring and settling when the total phosphorus concentration in the culture solution is reduced to be less than 40% of the initial concentration, preferably 10% -20%, discharging the supernatant, and leaving thalli;
(3) and (3) taking the thalli obtained in the step (2) as activated sludge, repeating the processes in the step (1) and the step (2) until the relative abundance of the nitrifying bacteria and the denitrifying phosphorus-accumulating bacteria in the cultured flora respectively accounts for more than 15%, and finishing the culture.
In the method, the ammonia nitrogen concentration of the culture solution used for the first time is 30-50mg/L, the COD concentration is 90-150mg/L, the total phosphorus concentration is 3-5mg/L, the ammonia nitrogen concentration of the culture solution used for the final time is 100-300mg/L, the COD concentration is 300-600mg/L, and the total phosphorus concentration is 10-30 mg/L. The concentration of the substrate in the culture solution is gradually increased, the increasing range of each time is 30-50mg/L according to ammonia nitrogen, the COD is 90-150mg/L, and the total phosphorus is 3-5 mg/L. The culture solution has the conditions for increasing the concentration of the matrix as follows: and (3) when the time taken for completing the step (1) and the step (2) by adopting the culture solution with the current substrate concentration is less than 60 percent (for example, 40 to 60 percent) of the time taken for completing the step (1) and the step (2) by using the culture solution with the same substrate concentration for the first time, increasing the substrate concentration in the culture solution used for the next time.
In the method, the activated sludge contains nitrifying bacteria and denitrifying phosphorus-accumulating bacteria, wherein the nitrifying bacteria and the denitrifying phosphorus-accumulating bacteria can be contained in the original sludge or can be added later. In the method, the activated sludge which is inoculated in the step (1) and is rich in nitrobacteria and denitrifying phosphorus-accumulating bacteria is taken from sludge in a secondary sedimentation tank of a sewage treatment plant for treating sewage containing nitrogen and phosphorus, the inoculation amount is 2000-5000mg/L, and the relative abundance values of the nitrobacteria and the denitrifying phosphorus-accumulating bacteria on the level are 0.1-1.0 percent and 0.1-1.0 percent respectively.
In the method of the present invention, the free amino acid in step (1) includes at least one of proline, hydroxyproline, glycine, arginine, and the like, preferably proline. The amount of the free amino acid used in the step (1) is 0.001-1.0mg/L, preferably 0.01-0.10 mg/L.
In the method of the present invention, the culture conditions in step (1) are: the concentration of dissolved oxygen is 0.5-1.5mg/L, the pH is 7-8, and the temperature is 25-35 ℃.
In the method of the present invention, the sugar ester substance in step (2) comprises at least one of rhamnose ester, trehalose glycolipid, sophorolipid, sucrose ester, etc., preferably rhamnose ester. The quaternary ammonium base is at least one of phosphorylcholine, betaine, tetramethylammonium hydroxide and the like, and the phosphorylcholine is preferred. The dosage of the sugar ester substance in the step (2) is 0.001-1.0mg/L, preferably 0.01-0.10 mg/L. The dosage of the quaternary ammonium base is 0.001-1.0mg/L, preferably 0.01-0.10 mg/L.
In the method, the culture conditions of the denitrifying phosphorus accumulating bacteria in the step (2) are as follows: the concentration of dissolved oxygen is 0-0.5mg/L, the pH is 7-8, and the temperature is 25-35 ℃.
In the method of the present invention, the conditions for finishing the culture are such that the relative abundance of the cultured flora at the level of nitrifying bacteria and denitrifying polyphosphates respectively accounts for more than 15%, preferably 20% -45% and 20% -45%, respectively.
The nitrifying bacteria and denitrifying phosphorus accumulating bacteria enriched by the method can be directly added into activated sludge of a sewage treatment plant for use, and can also be used for treating wastewater containing nitrogen and phosphorus in a proper biochemical reactor.
The method of the invention has the following advantages:
(1) in the process of culturing nitrobacteria, free amino acid is added, so that the effective transfer of oxygen and the full utilization of multiple matrixes can be improved, the substrate competition of autotrophic nitrobacteria and heterotrophic nitrobacteria is facilitated, the enzyme activity is stimulated to increase the number of nitrobacteria, the nitrification capability is improved, the competition of phosphorus accumulating bacteria and nitrobacteria on dissolved oxygen can be reduced, and the aerobic phosphorus uptake capability of the phosphorus accumulating bacteria is improved.
(2) In the culture process of the denitrifying phosphorus-accumulating bacteria, the sugar ester substances and the quaternary ammonium base are added in a matching way, so that the activity of nitrate reductase can be improved, the utilization of the denitrifying bacteria on the nitrate electron acceptor is enhanced, and the growth and the propagation of the denitrifying phosphorus-accumulating bacteria are promoted.
(3) The invention adds specific substances aiming at different culture stages, can promote the cooperative growth of multiple floras, realizes the common enrichment of nitrobacteria and denitrifying phosphorus-accumulating bacteria, is applied to a sewage treatment field, and can improve the effects of nitrogen and phosphorus removal.
Detailed Description
The technical solution of the present invention will be described in further detail with reference to examples. The embodiments are implemented on the premise of the technical scheme of the invention, and detailed implementation modes and specific operation processes are given, but the protection scope of the invention is not limited by the following embodiments.
The experimental procedures in the following examples are, unless otherwise specified, conventional in the art. The test materials used in the following examples were purchased from biochemical reagent stores unless otherwise specified.
In the method, the COD concentration is determined by GB11914-89 bichromate method which is the determination of chemical oxygen demand of water quality; the ammonia nitrogen concentration is measured by GB7478-87 (determination of ammonium water quality-distillation and titration method), the total nitrogen concentration is measured by GB 11894-89 (determination of water quality-total nitrogen-alkaline potassium persulfate digestion ultraviolet spectrophotometry), and the total phosphorus concentration is measured by GB11893-89 (ammonium molybdate spectrophotometry). The relative abundance at the level of nitrifying bacteria and denitrifying polyphosphates can be determined analytically using a high throughput sequencer.
Example 1
(1) Taking activated sludge in a secondary sedimentation tank of a sewage treatment plant, wherein the relative abundance values of nitrobacteria and denitrifying phosphorus bacteria on the level are 0.14 percent and 0.22 percent respectively, and inoculating the activated sludge into a 5L organic glass reactor with aeration and stirring functions for enrichment culture of thalli according to the sludge concentration (MLSS) after inoculation of about 3000 mg/L. The culture solution used for the first time had ammonia nitrogen concentration of 30mg/L, COD concentration of 90mg/L and total phosphorus concentration of 3mg/L, and proline was added at a concentration of 0.05 mg/L. The enrichment conditions of the nitrifying bacteria are as follows: the dissolved oxygen concentration is 1.0mg/L, the pH value is 7.5, the temperature is 30 ℃, when the ammonia nitrogen concentration in the culture solution is reduced to 10 percent of the initial concentration, the aeration is stopped, the stirring is started, and the culture stage of the denitrifying phosphorus-accumulating bacteria is started.
(2) Stopping aeration, starting stirring, adding rhamnose ester according to the concentration of 0.05mg/L, adding phosphorylcholine according to the concentration of 0.05mg/L after dissolved oxygen is reduced to less than 0.1mg/L, stopping stirring when the total phosphorus concentration is reduced to 20% of the initial concentration, settling for thirty minutes, discharging supernatant, and leaving thalli at the bottom.
(3) And (3) taking the thalli obtained in the step (2) as activated sludge, and repeating the processes of the step (1) and the step (2). Wherein, when the time for completing the step (1) and the step (2) by adopting the culture solution with the current substrate concentration is about 50 percent of the time for completing the step (1) and the step (2) by using the culture solution with the same substrate concentration for the first time, the substrate concentration in the culture solution used for the next time is increased. The concentration of the substrate in the culture solution is increased, the increasing range is 30mg/L according to ammonia nitrogen, COD is 90mg/L, and total phosphorus is 3 mg/L. Proline was added at a concentration of 0.05mg/L for each change of culture medium. The ammonia nitrogen concentration in the culture solution used for the last time is 150mg/L, the COD concentration is 450mg/L, and the total phosphorus concentration is 15 mg/L. And finally, the relative abundance of nitrobacteria and denitrifying phosphorus-accumulating bacteria in the cultured flora respectively reaches 30% and 40%, the culture is finished, and the thallus A is harvested for later use.
Example 2
The procedure and conditions were the same as in example 1, except that betaine was added at a concentration of 0.05mg/L after the dissolved oxygen was reduced to less than 0.1mg/L in the stage of culturing the denitrifying phosphorus accumulating bacteria. After the culture is finished, the relative abundance of nitrobacteria and denitrifying polyphosphates in the cultured flora respectively reaches 29% and 38%, and thallus B is harvested for later use.
Example 3
The culture process and conditions were the same as in example 1, except that trehalose ester and betaine were added at the stage of culturing the denitrifying phosphorus-accumulating bacteria at the stage of dissolved oxygen. After the culture is finished, the relative abundance of nitrobacteria and denitrifying polyphosphates in the cultured flora respectively reaches 27% and 36%, and thallus C is harvested for later use.
Example 4
(1) Taking activated sludge in a secondary sedimentation tank of a sewage treatment plant, wherein the relative abundance values of nitrobacteria and denitrifying phosphorus-accumulating bacteria on the level are 0.36 percent and 0.47 percent respectively, and inoculating the activated sludge into a 5L organic glass reactor with aeration and stirring functions for enrichment culture of thalli according to the sludge concentration (MLSS) after inoculation of about 4000 mg/L. The concentration of ammonia nitrogen in the culture solution for the first time is 50mg/L, the concentration of COD is 150mg/L, the concentration of total phosphorus is 5mg/L, and hydroxyproline is added according to the concentration of 0.01 mg/L. The enrichment conditions of the nitrifying bacteria are as follows: the dissolved oxygen concentration is 1.0mg/L, the pH value is 7.5, the temperature is 30 ℃, when the ammonia nitrogen concentration in the culture solution is reduced to 10 percent of the initial concentration, the aeration is stopped, the stirring is started, and the culture stage of the denitrifying phosphorus-accumulating bacteria is started.
(2) Stopping aeration, starting stirring, adding trehalose ester at the concentration of 0.01mg/L, adding betaine at the concentration of 0.05mg/L after dissolved oxygen is reduced to less than 0.1mg/L, stopping stirring when the total phosphorus concentration is reduced to 10% of the initial concentration, settling for thirty minutes, discharging supernatant, and leaving the bottom thallus.
(3) And (3) taking the thalli obtained in the step (2) as activated sludge, and repeating the processes of the step (1) and the step (2). Wherein, when the time for completing the step (1) and the step (2) by adopting the culture solution with the current substrate concentration is about 40 percent of the time for completing the step (1) and the step (2) by using the culture solution with the same substrate concentration for the first time, the substrate concentration in the culture solution used for the next time is increased. The concentration of the substrate in the culture solution is increased, the increasing range is 50mg/L according to ammonia nitrogen, COD is 100mg/L, and total phosphorus is 5 mg/L. Hydroxyproline was added at a concentration of 0.01mg/L for each replacement of the culture medium. The ammonia nitrogen concentration in the culture solution used for the last time is 300mg/L, the COD concentration is 550mg/L, and the total phosphorus concentration is 25 mg/L. And finally, the relative abundance of nitrobacteria and denitrifying phosphorus-accumulating bacteria in the cultured flora respectively reaches 25% and 34%, the culture is finished, and the thallus D is harvested for later use.
Example 5
(1) Taking activated sludge in a secondary sedimentation tank of a sewage treatment plant, wherein the relative abundance values of nitrobacteria and denitrifying phosphorus-accumulating bacteria on the level are 0.36 percent and 0.47 percent respectively, and inoculating the activated sludge into a 5L organic glass reactor with aeration and stirring functions for enrichment culture of thalli according to the sludge concentration (MLSS) after inoculation of about 3500 mg/L. The concentration of ammonia nitrogen in the culture solution for the first time is 40mg/L, the concentration of COD is 120mg/L, the concentration of total phosphorus is 4mg/L, and arginine is added according to the concentration of 0.1 mg/L. The enrichment conditions of the nitrifying bacteria are as follows: the dissolved oxygen concentration is 1.0mg/L, the pH value is 7.5, the temperature is 30 ℃, when the ammonia nitrogen concentration in the culture solution is reduced to 10 percent of the initial concentration, the aeration is stopped, the stirring is started, and the culture stage of the denitrifying phosphorus-accumulating bacteria is started.
(2) Stopping aeration, starting stirring, adding sucrose ester according to the concentration of 0.05mg/L, adding tetramethylammonium hydroxide according to the concentration of 0.01mg/L after the dissolved oxygen is reduced to less than 0.1mg/L, stopping stirring when the total phosphorus concentration is reduced to 15% of the initial concentration, settling for thirty minutes, discharging supernatant, and leaving the bottom thalli.
(3) And (3) taking the thalli obtained in the step (2) as activated sludge, and repeating the processes of the step (1) and the step (2). Wherein, when the time for completing the step (1) and the step (2) by adopting the culture solution with the current substrate concentration is about 60 percent of the time for completing the step (1) and the step (2) by using the culture solution with the same substrate concentration for the first time, the substrate concentration in the culture solution used for the next time is increased. The concentration of the substrate in the culture solution is increased, the increasing range is 40mg/L according to ammonia nitrogen, COD is 100mg/L, and total phosphorus is 5 mg/L. Arginine was added at a concentration of 0.1mg/L for each change of the culture medium. The ammonia nitrogen concentration in the culture solution used for the last time is 200mg/L, the COD concentration is 500mg/L, and the total phosphorus concentration is 25 mg/L. And finally, the relative abundance of nitrobacteria and denitrifying phosphorus-accumulating bacteria in the cultured flora respectively reaches 24% and 36%, the culture is finished, and the thallus E is harvested for later use.
Comparative example 1
In comparison with example 1, except that 0.05mg/L of proline was added instead of betaine in the enrichment stage of nitrifying bacteria in step (1), thallus F was harvested under the same total culture time as in example 1, wherein the relative abundances at the nitrifying bacteria and denitrifying polyphosphazenes level reached 16% and 12%, respectively.
Comparative example 2
In comparison with example 1, with the exception that no rhamnose ester and phosphorylcholine were added in step (2), and in the same total culture time as in example 1, the bacterial cells G were harvested, in which the relative abundance at the level of nitrifying bacteria and denitrifying polyphosphates reached 18% and 10%, respectively.
Comparative example 3
Compared with example 1, except that in step (2), while adding rhamnose ester, phosphorylcholine was added, and in the same total culture time as in example 1, thallus H was harvested, wherein the relative abundance at the level of nitrifying bacteria and denitrifying polyphosphates reached 17% and 16%, respectively.
Comparative example 4
In comparison with example 1, with the exception that the substrate concentration in the culture broth was not increased during the culture, thallus I was harvested in which the relative abundance at the level of nitrifying bacteria and denitrifying polyphosphates reached 21% and 18%, respectively, at the same total culture time as in example 1.
Effect verification
And (3) taking 10 reactors with effective volumes of 5L in a laboratory to verify the denitrification and dephosphorization effects of the thalli. The quality of the sewage for the experiment is 100mg/L of ammonia nitrogen concentration, 300mg/L of total nitrogen concentration 110mg/L, COD concentration and 8mg/L of total phosphorus concentration. Activated sludge was inoculated into the reactor at a sludge concentration of 2000mg/L, and then the cells harvested in the above examples and comparative examples were inoculated into the respective reactors in the same inoculum size. The SBR process is adopted for treatment, the dissolved oxygen in the stirring stage is controlled to be 0.5mg/L, the dissolved oxygen in the aeration stage is controlled to be 3mg/L, the pH value is 7.8, the temperature is 32 ℃, the reaction is finished after 24 hours, the concentration of pollutants in the supernatant in each reactor is sampled and analyzed, and the specific results are shown in Table 1.
TABLE 1 treatment Effect of different cells
Thallus
|
COD of the effluent in mg/L
|
Outlet water NH3-N,mg/L
|
Total nitrogen in effluent mg/L
|
Total phosphorus in the effluent in mg/L
|
Bacterium A
|
43.2
|
7.9
|
25.1
|
0.49
|
Bacterium B
|
48.6
|
8.2
|
27.4
|
0.56
|
Bacterium C
|
49.1
|
9.4
|
28.3
|
0.53
|
Cell D
|
52.3
|
11.3
|
29.4
|
0.67
|
Bacterium E
|
54.4
|
10.7
|
30.1
|
0.71
|
Cell F
|
51.8
|
12.1
|
37.9
|
4.96
|
Cell G
|
55.7
|
13.6
|
38.8
|
4.81
|
Bacterium H
|
57.3
|
14.2
|
41.8
|
3.93
|
Bacterium I
|
62.6
|
18.3
|
47.0
|
4.89
|
No bacteria control
|
75.2
|
21.4
|
56.7
|
7.12 |
As can be seen from the data in Table 1, the COD concentration of the treated effluent is lower than 55mg/L, the ammonia nitrogen concentration is lower than 12mg/L, the total nitrogen concentration is lower than 35mg/L, and the total phosphorus concentration is lower than 1.0mg/L by using the cultured thalli, the biological treatment effect of the sewage is obviously improved, and the simultaneous denitrification and dephosphorization are realized.