A method for enhancing denitrification in an Anammox-DAMO coupling system

Abstract

The invention discloses a method for strengthening the denitrification of an Anammox-DAMO coupling system, and belongs to the technical field of sewage microbial denitrification. The method of the invention uses magnetite-loaded activated carbon and growth factors as reinforcing agents to strengthen the denitrification of the Anammox-DAMO coupling system, and has the advantages of small amount of reinforcing agent addition and convenient operation; and can effectively improve the utilization efficiency of methane, strengthen the interspecies electron transfer process of microorganisms, facilitate the coupling of DAMO microorganisms and Anammox bacteria, and improve the growth rate and activity of DAMO microorganisms and Anammox bacteria, and has good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of sewage microbial denitrification, and in particular to a method for strengthening denitrification of an Anammox-DAMO coupling system. Background Art

[0002] As people's living standards continue to improve, a large amount of nitrogen-containing wastewater is produced. This wastewater must be effectively treated before it can be discharged in compliance with the standards. The existing denitrification technologies mainly include physical, chemical and biological methods. Biological denitrification technology has attracted much attention due to its advantages such as good treatment effect, low operating cost and mild conditions.

[0003] Anaerobic ammonia oxidation (Anammox)-anaerobic methane oxidation denitrification (DAMO) coupling process is an advanced biological denitrification technology that can be used to treat high-nitrogen wastewater such as waste incineration leachate. The Anammox process can convert ammonia nitrogen and nitrite nitrogen into nitrogen gas (as shown in Formula 1), thereby achieving denitrification of wastewater, but 11% of nitrogen still exists in the effluent in the form of nitrate nitrogen, and it is impossible to achieve complete denitrification. The DAMO process uses CH4 as an electron donor and nitrate nitrogen or nitrite nitrogen as an electron acceptor for denitrification. Therefore, the nitrate nitrogen produced by Anammox can be further converted into nitrite nitrogen through the action of DAMO archaea (as shown in Formula 2), and nitrite nitrogen reacts with ammonia nitrogen again through Anammox or is directly converted into nitrogen gas through DAMO bacteria (as shown in Formula 3), and finally achieves complete denitrification. Compared with the traditional "nitrification-denitrification" denitrification process, the Anammox-DAMO coupling process has the advantages of no need for aeration, no need for external carbon source, and low greenhouse gas (N2O) emissions.

[0004] Anammox bacteria: NH4 + +1.32NO2 - →1.02N2+0.26NO3 - +2.03H2O(1)

[0005] DAMO Archaea: CH4+4NO3 - →CO2+4NO2 - +2H2O(2)

[0006] DAMO bacteria: 3CH4+8NO2 - +8H + →3CO2+4N2+10H2O(3)

[0007] However, due to the low solubility of methane in water (19 mg / L, 35°C), the utilization efficiency of DAMO microorganisms is limited, thus affecting the activity of DAMO microorganisms; in addition, the main functional microorganisms in the Anammox-DAMO coupling process are Anammox bacteria, DAMO archaea and DAMO bacteria, which usually take several weeks to several months to double, are sensitive to environmental changes, and have problems such as slow growth and difficulty in enrichment. Based on this, increasing the amount of methane dissolved in water, achieving and maintaining the rapid growth and large-scale enrichment of Anammox bacteria and DAMO microorganisms, improving the activity of functional microorganisms, and improving the overall process denitrification rate are urgent issues to promote the practical application of the Anammox-DAMO coupling process. Summary of the invention

[0008] The present invention provides a method for strengthening the denitrification of an Anammox-DAMO coupling system, which uses magnetite-loaded activated carbon and growth factors as reinforcing agents to strengthen the denitrification of the Anammox-DAMO coupling system, and has the advantages of small amount of reinforcing agent added and convenient operation; and can effectively improve the utilization efficiency of methane, strengthen the electron transfer process between microbial species, be beneficial to the coupling of DAMO microorganisms and Anammox bacteria, and improve the growth rate and activity of DAMO microorganisms and Anammox bacteria, and has good application prospects. The method of the present invention solves the problems of low methane utilization efficiency, slow enrichment and growth of functional microorganisms, low activity, and limited system denitrification rate in the existing Anammox-DAMO coupling system.

[0009] The present invention first provides a method for enhancing denitrification of an Anammox-DAMO coupling system, comprising the following steps:

[0010] Magnetite-loaded activated carbon, mixed sludge containing Anammox bacteria and DAMO bacteria, and growth factors are added to a reactor containing wastewater, and methane is introduced to react to denitrify the wastewater.

[0011] In the above method, the magnetite-loaded activated carbon is prepared by a method comprising the following steps:

[0012] (1) Soak the activated carbon in a dilute hydrochloric acid solution, wash until the pH is neutral, and then dry;

[0013] (2) soaking the activated carbon treated in step (1) in an iron solution, discarding the iron solution, and obtaining the magnetite-loaded activated carbon.

[0014] In the above method, the particle size of the activated carbon is 20 to 40 mesh;

[0015] The concentration of the dilute hydrochloric acid solution is 0.4-1.0 mol / L;

[0016] In step (1), the soaking is performed at room temperature for 1 to 5 hours, specifically 2 hours;

[0017] In step (2), the soaking is first ultrasonically vibrating for 1 to 2 hours and then stirring at room temperature for 4 to 24 hours;

[0018] The frequency of the ultrasonic vibration is 30 to 60 kHz;

[0019] The stirring speed is 80-120 rpm;

[0020] The iron solution is a solution containing FeSO4 and FeCl3; specifically, the concentration of FeSO4 is 0.01-0.03 mol / L; the concentration of FeCl3 is 0.02-0.06 mol / L;

[0021] Add 4.0±0.1g activated carbon to every 200mL iron solution.

[0022] After the ultrasonic vibration, the pH of the solution is adjusted to 11-12 and then stirred at room temperature; specifically, the substance for adjusting the pH is sodium hydroxide solution.

[0023] In the above method, the dosage of the magnetite-loaded activated carbon is 2-6 g of magnetite-loaded activated carbon / L of liquid phase; specifically, it can be 6 g of magnetite-loaded activated carbon / L of liquid phase.

[0024] In the above method, the growth factors are spermine, spermidine, capsaicin and betaine;

[0025] Specifically, the concentrations of spermine, spermidine, capsaicin and betaine in the liquid phase are 100 μmol / L, 100 μmol / L, 1-10 μmol / L, 10-100 μmol / L, respectively. More specifically, the concentrations of spermine, spermidine, capsaicin and betaine in the liquid phase are 100 μmol / L, 100 μmol / L, 10 μmol / L and 100 μmol / L, respectively.

[0026] In the above method, the volume of the mixed sludge containing Anammox bacteria and DAMO bacteria accounts for 20% to 40% of the volume of the liquid phase.

[0027] The above-mentioned liquid phase refers to the entire reaction system, including the mixed sludge and wastewater of Anammox bacteria and DAMO bacteria.

[0028] In the above method, the reaction is an anaerobic reaction; methane is introduced into the headspace of the reactor;

[0029] The reaction temperature is 35° C., the stirring speed is 120-160 rpm, and the pH is 6.5-8.5.

[0030] In the above method, the reactor is an SBR reactor, which is operated in a sequential batch mode.

[0031] In the above method, the drying temperature is 105°C.

[0032] In the above method, the wastewater is nitrogen-containing wastewater containing nitric nitrogen and ammonia nitrogen; specifically, the total nitrogen concentration of the wastewater is 30-160 mg / L, more specifically 40-120 mg / L, 60 mg / L, 80 mg / L or 100 mg / L; the mass concentration ratio of nitric nitrogen to ammonia nitrogen in the wastewater is 1-5:1; specifically 2-2.5:1.

[0033] The wastewater is ammonia nitrogen-containing leachate after "anaerobic digestion" treatment of waste incineration plant leachate and nitrate nitrogen-containing leachate after "anaerobic digestion + short-range nitrification + anaerobic ammonia oxidation" treatment. The room temperature in the present invention is well known to those skilled in the art, and is generally 15 to 35°C.

[0034] The present invention has the following beneficial effects:

[0035] (1) The present invention uses activated carbon as a carrier, loads magnetite, and adds multiple growth factors to develop a method for enhancing the denitrification of the Anammox-DAMO coupling system, which can effectively increase the methane oxidation rate and denitrification rate.

[0036] (2) The activated carbon in the present invention can adsorb methane and provide more electron donors for DAMO microorganisms; in addition, magnetite loaded on the activated carbon can shorten the spatial distance between the functional microorganisms and the magnetite, enhance the electron transfer rate between microorganisms, improve the activity of functional microorganisms, enhance the coupling between Anammox bacteria and DAMO microorganisms, and improve the overall denitrification rate.

[0037] (3) The growth factors used in the present invention have selective antibacterial effects, inhibit the growth of aerobic methane oxidizing bacteria, promote the biofilm formation of DAMO microorganisms and Anammox bacteria, and enhance the growth of functional bacteria; compared with the existing trace element promotion method, more suitable growth factor types, combinations and concentrations are selected, which is more targeted.

[0038] (4) The present invention can enhance the methane utilization efficiency, increase the growth rate and relative abundance of DAMO microorganisms and Anammox bacteria, enrich the direct interspecies electron transfer bacteria, improve the electron transfer efficiency between microorganisms, enhance the coupling of Anammox bacteria and DAMO microorganisms, and improve the denitrification rate of the Anammox-DAMO coupling system under the dual enhancement of magnetite-loaded activated carbon and growth factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the effect of the denitrification method of the enhanced Anammox-DAMO coupling system on the removal rates of ammonia nitrogen, nitrate nitrogen and total nitrogen; Figure 1 A is the change of ammonia nitrogen concentration over time; B is the ammonia nitrogen conversion rate in each cycle; C is the change of nitrate nitrogen concentration over time; D is the nitrate nitrogen conversion rate in each cycle; E is the change of total nitrogen concentration over time; F is the total nitrogen removal rate in each cycle.

[0040] Figure 2 Schematic diagram of growth factor screening to enhance the denitrification rate of the Anammox-DAMO coupling system; Figure 2 A is the nitrogen removal rate at different spermine concentrations; B is the nitrogen removal rate at different spermidine concentrations; C is the nitrogen removal rate at different capsaicin concentrations; D is the nitrogen removal rate at different betaine concentrations; E is the nitrogen removal rate of the blank group with methane in the headspace; F is the total nitrogen removal rate of the reactor for 30 days.

[0041] Figure 3 Diagram showing the denitrification effect of enhanced Anammox-DAMO coupling system in treating waste incineration leachate. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with specific embodiments. The given examples are only for illustrating the present invention, rather than for limiting the scope of the present invention.

[0043] The experimental methods in the following examples are all conventional methods unless otherwise specified.

[0044] The quantitative tests in the following examples were all repeated three times, and the results were averaged.

[0045] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0046] Example 1. Effects of magnetite-loaded activated carbon and growth factors on the denitrification rate of the Anammox-DAMO coupling system

[0047] (1) The source of Anammox-DAMO flora: According to Ding's culture method (Ding, ZW, et al., 2017. Simultaneous enrichment of denitrifying anaerobic methane-oxidizing microorganisms and anammox bacteria in a hollow-fiber membrane biofilm reactor. Appl Microbiol Biotechnol. 101, 437-446.), an active and stable Anammox-DAMO flora was obtained using nitrate nitrogen and ammonia nitrogen as nitrogen sources. The pH value was 7.31 and the TSS value was 4.39 g / L.

[0048] (2) Preparation of magnetite-loaded activated carbon: 20-40 mesh granular activated carbon purchased from Sigma-Aldrich was rinsed with deionized water until the supernatant was clear and transparent, then soaked in 0.4 mol / L hydrochloric acid solution at room temperature for 2 hours, then washed with deionized water until the pH was neutral, and dried in an oven at 105°C; 5 g of the treated activated carbon was added to 250 mL of iron solution and ultrasonically soaked for 1 hour, wherein the iron solution contained 0.01 mol / L FeSO4·7H2O and 0.02 mol / L FeCl3·6H2O, and the ultrasonic frequency was 40 kHz; after ultrasonic soaking, 1.5 mol / L NaOH solution was added to adjust the pH to 12, and the mixture was stirred at 100 rpm in a constant temperature magnetic stirrer at 25°C for 24 hours, the soaked iron solution was discarded, and the obtained magnetite-loaded activated carbon was rinsed with deionized water until neutral, dried in an oven at 105°C, and stored in a cool place for later use.

[0049] (3) Treatment of magnetite: The magnetite ore was crushed with a mechanical crusher and sieved to obtain magnetite particles with a particle size of 1 to 2 mm. The magnetite particles were soaked in 1 mol / L hydrochloric acid for 24 hours to remove surface impurities, then washed with deionized water until neutral, and dried in a vacuum drying oven for 12 hours.

[0050] (4) Preparation of growth factor concentrate: The growth factor concentrate includes the following ingredients: spermine 10000 μmol / L, spermidine 10000 μmol / L, capsaicin 1000 μmol / L and betaine 10000 μmol / L; the solvent is water.

[0051] (5) Preparation of mineral culture medium: The mineral culture medium was prepared according to the method described by Ettwig (Ettwig, KF, et al., 2009. Enrichment and molecular detection of denitrifying methanotrophic bacteria of the NC10 phylum. Appl Environ Microbiol. 75, 3656-62.), and its specific composition was: 0.05 g / L KH2PO4, 0.5 g / L KHCO3, 0.3 g / L CaCl2·2H2O, 0.165 g / L MgSO4·7H2O, 0.5 mL / L acidic trace element solution and 0.2 mL / L alkaline trace element solution.

[0052] The composition of the acidic trace element solution is: 100mmol / L HCl, 2.085g / L FeSO4·7H2O, 0.068g / L ZnSO4·7H2O, 0.12g / L CoCl2·6H2O, 0.5g / L MnCl2·4H2O, 0.32g / L CuSO4, 0.095g / L NiCl2·6H2O, 0.014g / L H3BO3; the composition of the alkaline trace element solution is: 10mmol / LNaOH, 0.114g / L Na2SeO4, 0.05g / L Na2WO4·2H2O, 0.242g / L Na2MoO4.

[0053] The solvent is water.

[0054] (6) The experiment used a 500 mL SBR reactor, into which 100 mL of the Anammox-DAMO bacterial community described in (1) was added, and then the mineral culture solution, nitrate nitrogen concentrate and ammonia nitrogen concentrate described in (5) were added to make the total volume of the liquid phase 300 mL, the concentration of the nitrate nitrogen concentrate was 3000 mg / L nitrate nitrogen (18.21 g NaNO3 / L), the concentration of the ammonia nitrogen concentrate was 3000 mg / L ammonia nitrogen (16.92 g NH4HCO3 / L), and the concentrated solution was added to adjust the initial nitrate nitrogen and ammonia nitrogen concentrations of the system to 80 mg / L; the pH of the liquid phase was 6.5-8.5. Reactor R-1 is a blank group with only bacteria added; Reactor R-2 is added with 1.8g 20-40 mesh granular activated carbon; Reactor R-3 is added with 1.8g magnetite particles treated by (3); Reactor R-4 is added with 1.8g magnetite-loaded activated carbon; Reactor R-5 is added with 3mL growth factor concentrate; Reactor R-6 is added with 1.8g magnetite-loaded activated carbon and 3mL growth factor concentrate. The 6 closed reactors were first introduced into the liquid phase with nitrogen for 30 minutes to remove oxygen, and then methane was introduced at a flow rate of 20mL / min for 10 minutes, so that the 200mL gas phase in the headspace was all methane gas. Methane can provide electron donors for DAMO microorganisms, and then placed in a 35℃ constant temperature shaker for denitrification. The concentration changes of nitrate nitrogen, ammonia nitrogen and total nitrogen in all reactors were measured every two days by spectrophotometry. After 6 reactors were settled for 12 hours every 10 days, methane gas was introduced into the reactor headspace and 200 mL of supernatant was discharged, and then 200 mL of mineral culture medium was added. Then, by adding 1000 mg / L nitrate nitrogen (6.07 g NaNO3 / L) or 1000 mg / L ammonia nitrogen (5.64 g NH4HCO3 / L) concentrated solution, the initial nitrate nitrogen and ammonia nitrogen concentrations of each cycle were adjusted to 80 mg / L, and the removal rates of nitrate nitrogen, ammonia nitrogen and total nitrogen were calculated by linear regression. The results are shown in Figure 1 As shown in the figure, after 30 days of operation, the total nitrogen removal rates of the six reactors R-1, R-2, R-3, R-4, R-5, and R-6 were 4.12 mg / (L·d), 4.03 mg / (L·d), 5.06 mg / (L·d), 8.39 mg / (L·d), 4.92 mg / (L·d), and 13.19 mg / (L·d), respectively. It can be seen that after 30 days of cultivation, the total nitrogen removal rate in the reactor R-6 enhanced by adding magnetite-loaded activated carbon and growth factors was 3.20 times that of the blank reactor R-1.

[0055] Example 2: Effects of magnetite-loaded activated carbon and growth factors on the functional microbial community structure of the Anammox-DAMO coupling system

[0056] (1) Two 500 mL SBR reactors SBR-1 and SBR-2 with the same structure were simultaneously added with 200 mL of the same mineral culture solution as in Example 1 and 100 mL of the same Anammox-DAMO bacterial flora as in Example 1, and 3000 mg / L of nitrate nitrogen (18.21 g NaNO3 / L) and 3000 mg / L of ammonia nitrogen (16.92 g NH4HCO3 / L) concentrated solutions were added to adjust the initial nitrate nitrogen and ammonia nitrogen concentrations of the system to 50 mg / L, and the pH of the liquid phase was 6.5-8.5. 1.8 g of magnetite-loaded activated carbon (prepared by the method described in Example 1) and growth factors were added to SBR-2, so that the concentrations of the growth factors in the liquid phase were 100 μmol / L of spermine, 100 μmol / L of spermidine, 100 μmol / L of capsaicin, and 100 μmol / L of betaine. Magnetite-loaded activated carbon and growth factors were not added to SBR-1, which was used as a blank group. The reactor liquid phase was introduced with nitrogen for 30 minutes to remove oxygen, and then methane was introduced at a flow rate of 20 mL / min for 10 minutes, so that the headspace gas phase was all methane gas, providing electron donors for DAMO microorganisms, and placed in a 35°C constant temperature shaker for denitrification. The shaker rotation frequency was 155 rpm, and the concentrations of nitrate nitrogen, ammonia nitrogen and total nitrogen in the two reactors were measured every two days. When the concentration of nitrate nitrogen or ammonia nitrogen was less than 5 mg / L, 3000 mg / L nitrate nitrogen (18.21 g NaNO3 / L) or 3000 mg / L ammonia nitrogen (16.92 g NH4HCO3 / L) concentrated solution was added to adjust the concentration of nitrate nitrogen or ammonia nitrogen to 50 mg / L, and methane was introduced at a flow rate of 20 mL / min for 10 minutes. After 30 days of continuous operation, 5 mL of sludge from SBR-1 and SBR-2 was taken out to determine the microbial community structure in the sludge. The results showed that after 30 days of cultivation, the relative abundances of DAMO bacteria, DAMO archaea and Anammox bacteria in the SBR-1 reactor were 23.8%, 0.16% and 0.59%, respectively; the relative abundances of DAMO bacteria, DAMO archaea and Anammox bacteria in the SBR-2 reactor were 31.3%, 0.39% and 0.82%, respectively. It can be seen that the addition of magnetite-loaded activated carbon and growth factors is conducive to the enrichment and growth of DAMO bacteria, DAMO archaea and Anammox bacteria. The relative abundances of DAMO bacteria, DAMO archaea and Anammox bacteria in the experimental group were 1.32 times, 2.44 times and 1.39 times that of the blank group, respectively.

[0057] Example 3: Effect of growth factors on the denitrification rate of the Anammox-DAMO coupling system

[0058] (1) The growth factors screened include: multivitamins, heme, bases, betaine, capsaicin, spermine, and spermidine. Among them, the multivitamins are cobalamin, biotin, folic acid, riboflavin, pyridoxine, pantothenic acid, and niacin. After preliminary anaerobic vial experiment screening, it was determined that betaine, capsaicin, spermine and spermidine have a promoting effect on the denitrification rate of the Anammox-DAMO coupling system. The optimal concentrations of these four growth factors were further screened, and betaine 0.1μmol / L, 1μmol / L, 10μmol / L, 100μmol / L, 1mmol / L; capsaicin 0.1μmol / L, 1μmol / L, 10μmol / L, 100μmol / L, 1mmol / L; spermine 0.01μmol / L, 0.1μmol / L, 1μmol / L, 10μmol / L, 100μmol / L; spermidine 0.01μmol / L, 0.1μmol / L, 1μmol / L, 10μmol / L, 100μmol / L. To determine the optimal concentration.

[0059] (2) The solid powder of the growth factor further screened in concentration described in (1) was prepared into a solution at an appropriate concentration and injected into anaerobic vials according to the type and concentration. The anaerobic vials included 70 mL of gas phase and 50 mL of liquid phase, wherein the liquid phase included 20 mL of the Anammox-DAMO bacterial flora described in Example 1 and 30 mL of the mineral culture solution described in Example 1 and a nitrogen concentrate. The nitrogen concentrates included a 4000 mg / L nitrate nitrogen (24.28 g NaNO3 / L) concentrate and a 4000 mg / L ammonia nitrogen (22.56 g NH4HCO3 / L) concentrate. The nitrogen concentrate was used to adjust the initial nitrate nitrogen and ammonia nitrogen concentrations of the system to 80 mg / L, and the pH of the liquid phase was 6.5-8.5. In addition, a blank group with only bacteria was set up. The setting method of the blank group was the same as above, except that no growth factor was added. Nitrogen was first introduced into the anaerobic vial for 30 minutes to remove oxygen, and then methane was introduced at a flow rate of 20 mL / min for 5 minutes, so that the headspace gas phase was all methane gas, providing an electron donor for DAMO bacteria, and then placed in a 35°C constant temperature shaker for denitrification, with a shaker rotation frequency of 155 rpm. The concentrations of nitrate nitrogen, ammonia nitrogen and total nitrogen in the two reactors were measured every two days, and methane was introduced at a flow rate of 20 mL / min for 5 minutes every 10 days. The changes in nitrogen concentration were monitored by spectrophotometry, and the nitrogen removal rate was calculated by linear regression. The results are shown in Figure 2As shown, after 30 days of operation, the maximum nitrogen removal rate was 0.52 mg / (L·d) when the spermine concentration was 100 μmol / L, the maximum nitrogen removal rate was 0.56 mg / (L·d) when the spermidine concentration was 100 μmol / L, the maximum nitrogen removal rate was 4.69 mg / (L·d) when the capsaicin concentration was 1 mmol / L, and the maximum nitrogen removal rate was 1.72 mg / (L·d) when the betaine concentration was 1 mmol / L. In order to verify whether the denitrification process at this time was heterotrophic microbial denitrification or DAMO microbial denitrification, an anaerobic vial experiment in which the headspace did not provide methane but nitrogen was supplemented, as shown in Figure 2 As shown in E, when capsaicin was 100 μmol / L, 1 mmol / L and betaine was 1 mmol / L, denitrification occurred without providing methane, indicating that denitrification at this time was a heterotrophic denitrification reaction rather than a DAMO reaction that required methane as an electron donor, and the increase in heterotrophic denitrifying bacteria would inhibit the growth of DAMO bacteria. Therefore, the optimal growth factor combination of spermine 100 μmol / L, spermidine 100 μmol / L, capsaicin 10 μmol / L and betaine 100 μmol / L was used.

[0060] (3) 100 mL of the Anammox-DAMO bacterial flora described in Example 1 was injected into two 500 mL SBR reactors SBR-1 and SBR-2 with the same structure, and 200 mL of the mineral culture solution described in Example 1 was added at the same time. A concentrated solution of 3000 mg / L nitrate nitrogen (18.21 g NaNO3 / L) and 3000 mg / L ammonia nitrogen (16.92 g NH4HCO3 / L) was added to adjust the initial nitrate nitrogen and ammonia nitrogen concentrations of the system to 80 mg / L, and the pH of the liquid phase was 6.5-8.5. In addition, the optimal growth factor combination described in (2) was added to SBR-2 (i.e., the concentration of the growth factor in the entire liquid phase was 100 μmol / L spermine, 100 μmol / L spermidine, 10 μmol / L capsaicin and 100 μmol / L betaine), and no growth factor was added to SBR-1, which served as a blank group. Nitrogen was introduced into the liquid phase of the reactor for 30 minutes to remove oxygen, and then methane was introduced at a flow rate of 20 mL / min for 10 minutes to provide electron donors for DAMO microorganisms, and then placed in a 35°C constant temperature shaker for denitrification. The shaker rotation frequency was 155 rpm. The nitrogen concentration in the two reactors was measured every two days. When the nitrate nitrogen or ammonia nitrogen concentration was less than 5 mg / L, 3000 mg / L nitrate nitrogen (18.21 g NaNO3 / L) or 3000 mg / L ammonia nitrogen (16.92 g NH4HCO3 / L) nitrogen concentrate was added to adjust the nitrogen concentration to 80 mg / L, and methane was introduced at a flow rate of 20 mL / min for 10 minutes to ensure sufficient methane gas in the headspace. The change in nitrogen concentration in the reactor was determined by spectrophotometry, and the nitrogen removal rate was calculated by linear regression. The results are as follows: Figure 2 As shown in Figure F, after 30 days of operation, the total nitrogen removal rates of the two reactors SBR-1 and SBR-2 were 3.01 mg / (L·d) and 6.92 mg / (L·d), respectively. It can be seen that after 30 days of cultivation, the total nitrogen removal rate in the reactor SBR-2 enhanced by adding growth factor combination was 2.30 times that of the blank reactor SBR-1.

[0061] Example 4: Effects of Magnetite-Loaded Activated Carbon and Growth Factors on the Denitrification Efficiency of Anammox-DAMO Coupling System in Treating Waste Incineration Leachate

[0062] (1) Treatment object: The leachate containing ammonia nitrogen after the "anaerobic digestion" treatment of the waste incineration plant and the leachate containing nitrate nitrogen after the "anaerobic digestion + short-range nitrification + anaerobic ammonium oxidation" treatment are mixed in a volume ratio of 1:8. The total nitrogen concentration of this leachate is 90-120 mg / L; the mass concentration ratio of nitrate nitrogen to ammonia nitrogen is 2-2.5:1.

[0063] (2) 100 mL of the Anammox-DAMO bacterial community described in Example 1 was injected into two 500 mL SBR reactors SBR-1 and SBR-2 of the same structure, and 200 mL of the mineral culture solution described in Example 1 was added. 1.8 g of magnetite-loaded activated carbon described in Example 1 and the optimal growth factor combination described in Example 3 (2) (i.e., the initial concentration of the growth factor in the SBR was 100 μmol / L of spermine, 100 μmol / L of spermidine, 100 μmol / L of capsaicin and 100 μmol / L of betaine) were added to SBR-2, and no magnetite-loaded activated carbon and growth factor were added to SBR-1, which served as a blank group. The pH of the liquid phase was 6.5-8.5. Nitrogen was introduced into the liquid phase of the two SBR reactors for 30 minutes to remove oxygen, and then methane was introduced at a flow rate of 20 mL / min for 10 minutes to fill the headspace with methane gas to provide electron donors for DAMO microorganisms, and then placed in a 35°C constant temperature shaker for denitrification. The shaking table rotation frequency was 155rpm. The HRT of the two SBRs was set to 6 days. Every two days was a water inlet and outlet cycle, and each cycle included 48 minutes of static sedimentation, 1 minute of supernatant discharge, 1 minute of leachate inlet, 20mL / min of methane gas aeration for 10 minutes, and 47 hours of operation in the shaking table. The volume of the discharged water and the inlet leachate was the same each time and was 100mL.

[0064] (3) Initially, the influent of the two SBR reactors was the diluted leachate (1) (total nitrogen = 40 mg / L). After 10 cycles (20 days) of operation, the total nitrogen concentration of the effluent of the two SBRs was <10 mg / L. Thereafter, the load increase phase was entered. The total nitrogen concentration of the influent of the SBR-2 reactor was increased from 40 mg / L to 60 mg / L, 80 mg / L, 100 mg / L, and 120 mg / L. Each load was operated for 10 cycles (20 days), and a total of 50 cycles (100 days). Stability was achieved when the influent total nitrogen concentration was 100 mg / L, and the total nitrogen removal rate during the stable period was above 80%. The SBR-1 reactor in the blank group could achieve a removal rate of more than 80% when the influent total nitrogen was 60 mg / L. When the influent was further increased to 80 mg / L, the removal rate of the reactor dropped significantly (see Figure 3 ). It can be seen that the addition of magnetite-loaded activated carbon and growth factors can significantly improve the denitrification efficiency, making the denitrification capacity of the Anammox-DAMO coupling system for waste incineration leachate increase by 1.67 times.

Claims

1. A method for enhancing denitrification in an Anammox-DAMO coupling system, Features: The method comprises the following steps: Adding magnetite-loaded activated carbon, mixed sludge containing Anammox bacteria and DAMO bacteria, and growth factors into a reactor containing wastewater, and introducing methane to react and denitrify the wastewater; The growth factors are spermine, spermidine, capsaicin and betaine.

2. The method according to claim 1, Features: The magnetite-loaded activated carbon is prepared by the following steps: (1) Soak the activated carbon in a dilute hydrochloric acid solution, wash it until the pH is neutral, and then dry it; (2) Soaking the activated carbon treated in step (1) in an iron solution, discarding the iron solution, and obtaining the magnetite-loaded activated carbon.

3. The method according to claim 2, Features: The particle size of the activated carbon is 20-40 mesh; The concentration of the dilute hydrochloric acid solution is 0.4-1.0 mol / L; In step (1), the soaking is performed at room temperature for 1 to 5 hours; In step (2), the soaking is first ultrasonically vibrating for 1 to 2 hours and then stirring at room temperature for 4 to 24 hours; The frequency of the ultrasonic vibration is 30 to 60 kHz; The stirring speed is 80-120 rpm; The iron solution contains FeSO 4 and FeCl 3 solution; specifically, the FeSO 4 The concentration of FeCl is 0.01~0.03 mol / L; 3 The concentration is 0.02~0.06 mol / L; Add 4.0 ± 0.1 g of activated carbon to every 200 mL of iron solution.

4. The method according to any one of claims 1 to 3, Features: The dosage of the magnetite-loaded activated carbon is 2-6 g of magnetite-loaded activated carbon / L of liquid phase.

5. The method according to any one of claims 1 to 3, Features: The concentrations of spermine, spermidine, capsaicin and betaine in the liquid phase are 100 μmol / L, 100 μmol / L, 1-10 μmol / L and 10-100 μmol / L, respectively.

6. The method according to any one of claims 1 to 3, Features: The volume of the mixed sludge containing Anammox bacteria and DAMO bacteria accounts for 20% to 40% of the volume of the liquid phase.

7. The method according to any one of claims 1 to 3, Features: The reaction is an anaerobic reaction; The reaction temperature is 35° C., the stirring speed is 120-160 rpm, and the pH is 6.5-8.

5.

8. The method according to any one of claims 1 to 3, Features: The reactor is a SBR reactor, which is operated in a sequential batch mode.

9. The method according to any one of claims 1 to 3, Features: The wastewater is nitrogen-containing wastewater containing nitric nitrogen and ammonia nitrogen.

10. The method according to claim 9, Features: The total nitrogen concentration of the wastewater is 30-160 mg / L; The mass concentration ratio of nitric nitrogen to ammonia nitrogen in the wastewater is 1-5:1.

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