A method for enhancing the total nitrogen removal rate of anaerobic ammonium oxidation granular sludge using aluminum ions

Abstract

This invention discloses a method for improving the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions. The method involves adding 5-20 mg / L of aluminum chloride hexahydrate to a stably operating anaerobic ammonia oxidation granular sludge SBR reactor. Under the influence of aluminum ions, on the one hand, the zeta potential of the anaerobic ammonia oxidation granular sludge surface is increased, leading to a decrease in electrostatic repulsion on the granular sludge surface, thereby promoting sludge granulation; on the other hand, the addition of aluminum ions in the reactor forms polymers, which create a protective layer on the granular sludge surface, helping to resist the inhibitory effect of dissolved oxygen on anaerobic ammonia oxidation bacteria, promoting the activity of anaerobic ammonia oxidation bacteria, and thus improving the total nitrogen removal rate. However, excessively high aluminum ion concentrations can also have a negative impact on pollutant degradation. Therefore, adding an appropriate concentration of aluminum ions is of great significance for the removal of total nitrogen from wastewater, and the method of this invention provides a new approach for the efficient removal of total nitrogen from wastewater.

Description

Technical Field

[0001] This invention belongs to the field of urban wastewater treatment and recycling, and specifically relates to a method for improving the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions. Background Technology

[0002] In recent years, with the development of society and the economy, nitrogen pollution has become a widespread and significant environmental problem. Anaerobic ammonia oxidation (AAO), with its significant advantages of low carbon emissions and high efficiency, has become a research hotspot in the field of wastewater treatment. However, the anaerobic bacteria, the main executors of the AAO process, have a long doubling time and low growth rate, which greatly affects the widespread application of the AAO process. Anaerobic ammonia oxidation granular sludge, as the most promising sludge form for realizing the AAO process, has significant practical implications for improving the total nitrogen removal rate. Summary of the Invention

[0003] To address the shortcomings and deficiencies of existing technologies, the present invention aims to provide a method for enhancing the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions.

[0004] The principle of this invention is as follows: Adding a certain concentration of aluminum chloride hexahydrate to a stably operating anaerobic ammonia oxidation granular sludge reactor, under the influence of stirring and aluminum ions, increases the zeta potential on the surface of the anaerobic ammonia oxidation granular sludge, reducing electrostatic repulsion and promoting sludge granulation. Furthermore, the addition of aluminum ions forms polymers in the reactor, creating a protective layer on the granular sludge surface. This layer helps resist the inhibitory effect of dissolved oxygen on anaerobic ammonia oxidizing bacteria, promoting their activity and thus increasing the total nitrogen removal rate. However, the added aluminum ions should be within a suitable concentration range. Excessive aluminum ion concentration can be toxic to microorganisms, and the flocculation effect of aluminum ions can easily form a thick polymer layer on the granular sludge surface. This can hinder contact between microorganisms and pollutants in the wastewater, ultimately affecting microbial growth and pollutant removal efficiency.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for improving the total nitrogen removal rate of anammox granular sludge using aluminum ions includes the following steps: (1) inoculating anammox granular sludge into a reactor;

[0007] (2) Add wastewater and aluminum-containing solution to the reactor and stir during operation;

[0008] (3) After the operation is completed, stop stirring, let the sludge settle and idle, and wash the sludge with water before the operation on the second day.

[0009] (4) Repeat steps (2) to (3) for 1 to 50 days.

[0010] Preferably, the aluminum ion concentration in the aluminum-containing solution is 5–20 mg / L.

[0011] Preferably, the sludge concentration MLSS inoculated in the reactor is 8200-8600 mg / L. The sludge concentration MLSS (mixed liquor suspended solids concentration) refers to the suspended solids content of the mixed liquor after the sewage and activated sludge are mixed, and the unit is (mg / L), which is the concentration of pure sludge.

[0012] Preferably, the anaerobic ammonia oxidation granular sludge originates from a long-term stable-operation UASB reactor and is acclimated in a laboratory SBR model under the following acclimation conditions:

[0013] The sludge is placed in a reactor, and 0.200–0.205 g / L (NH4)2SO4, 0.275–0.280 g / L NaNO2 and 0.311–0.312 g / L NaHCO3 are added. The sludge is acclimatized and cultured at room temperature. When the total nitrogen removal rate of the reactor stabilizes at over 70%, the sludge in the reactor is removed to obtain the anaerobic ammonia oxidation granular sludge.

[0014] Preferably, the anaerobic ammonia oxidation granular sludge reactor is an anaerobic ammonia oxidation granular sludge sequencing batch reactor (SBR) reactor, and the temperature in the reactor is maintained at 30-35°C and the dissolved oxygen concentration is 0.2-0.5 mg / L.

[0015] Preferably, the influent substrate of the wastewater comprises 2.581-2.601 g / L (NH4)2SO4, 3.241-3.261 g / L NaNO2, and 3.923-3.933 g / L NaHCO3, controlling the influent ammonia nitrogen concentration to be 80-110 mg / L and the nitrite nitrogen concentration to be 100-120 mg / L.

[0016] Preferably, the stirring time is determined according to the degradation of pollutants, and is preferably 3.5 ± 0.5 hours.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] (1) This application can enhance the activity of anaerobic ammonia oxidizing bacteria under hypoxic conditions (dissolved oxygen concentration: 0.2-0.5 mg / L), thereby enhancing the anaerobic ammonia oxidation effect and thus enabling the reactor to achieve better denitrification effect.

[0019] (2) The aluminum ion concentration added in this application is low, and the aluminum salt compounds added are widely available. Compared with other methods to improve the total nitrogen removal rate, the cost is lower and the time to achieve the promoting effect is shorter.

[0020] (3) Aluminum salt flocculants are often added during wastewater treatment to enhance the treatment effect, which inevitably leads to a certain concentration of aluminum ions in the wastewater. This application can better guide the addition of aluminum salt flocculants and provide a more scientific guidance and reference for the promotion and application of anaerobic ammonia oxidation granular sludge.

[0021] (4) After adding aluminum ions, the average total nitrogen removal rate of this application is significantly improved compared with that without adding aluminum ions, increasing by 24% to 42%. Attached Figure Description

[0022] Figure 1 The total nitrogen removal rate of this invention is measured by adding aluminum ions at different concentrations (0, 10, 30, 50, 100, 200 mg / L) for 45 days.

[0023] Figure 2 The total nitrogen removal rate of this invention is measured by adding aluminum ions at different concentrations (0, 5, 10, 20 mg / L) for 9 days.

[0024] Figure 3 The percentage increase in total nitrogen removal rate compared to the control group is achieved by adding aluminum ions at different concentrations (0, 10, 30, 50, 100, 200 mg / L) for 45 days.

[0025] Figure 4 The percentage increase in total nitrogen removal rate compared to the control group after running the experiment for 9 days with aluminum ions at different concentrations (0, 5, 10, 20 mg / L) is shown in this invention.

[0026] Figure 5 The present invention relates to the Zeta potential obtained by adding aluminum ions at different concentrations (0, 10, 30, 50, 100, 200 mg / L) for 45 days. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0028] The reactor used in this invention is a sequencing batch reactor (SBR) with an effective volume of 0.5 L. A stirring device is installed above the reactor to ensure uniform mixing of sludge and water. Before the experiment, each reactor is inoculated with anaerobic ammonia oxidation granular sludge to achieve a sludge concentration (MLSS) of approximately 8500 mg / L. MLSS (mixed liquor suspended solids concentration) refers to the suspended solids content of the mixed liquor after mixing wastewater and activated sludge, expressed in mg / L, and is the concentration of pure sludge. The sludge is derived from a long-term stable UASB reactor and has undergone laboratory SBR acclimation under the following acclimation conditions:

[0029] A simple reactor was constructed using a 20L water tank and a built-in single-blade agitator. Anaerobic ammonia oxidation granular sludge was placed inside the reactor, and 0.200–0.205 g / L (NH4)2SO4, 0.275–0.280 g / L NaNO2, and 0.311–0.312 g / L NaHCO3 were added. The ratio of ammonia nitrogen to nitrite nitrogen in the influent was 1:1.3. The reactor was acclimatized and cultured at room temperature until the total nitrogen removal rate of the reactor stabilized at over 70%. Then, the granular sludge from the tank was transferred to a 1L SBR reactor for formal testing.

[0030] The SBR reactor was operated intermittently in chronological order. First, sludge wastewater was manually prepared daily. The influent substrate included 2.581-2.601 g / L (NH4)2SO4, 3.241-3.261 g / L NaNO2, and 3.923-3.933 g / L NaHCO3, controlling the influent ammonia nitrogen concentration at 80-110 mg / L and nitrite nitrogen concentration at 100-120 mg / L. Aluminum chloride hexahydrate was used to prepare an aluminum solution, controlling the aluminum ion concentration in each reactor at 5-20 mg / L. After inoculating the reactor with sludge, water was manually pumped to the 300 ml mark using a syringe, then fresh tap water was added to the 500 ml mark for sludge washing. After two rounds of washing, simulated sludge wastewater and aluminum solution were added sequentially. The agitator was turned on, and the reaction time was adjusted daily based on the ammonia nitrogen removal rate to maintain it at 70%-80%. The reaction temperature is controlled at 30–35°C using a water bath device, and the dissolved oxygen concentration is controlled at 0.2–0.5 mg / L.

[0031] After stirring, NH4 was determined by Nessler's reagent spectrophotometry, N-(1-naphthyl)-ethylenediamine spectrophotometry, and ultraviolet spectrophotometry, respectively. + -N, NO2 - -N, NO3 - The total nitrogen removal rate is calculated using the following formula based on the -N concentration:

[0032] Total nitrogen concentration = ammonia nitrogen concentration + nitrite nitrogen concentration + nitrate nitrogen concentration

[0033] Total nitrogen removal rate (mg N / (mg MLSS·h) = (total nitrogen concentration before stirring - total nitrogen concentration after stirring) / (total nitrogen concentration before stirring * stirring time * sludge concentration).

[0034] The units for total nitrogen concentration and sludge concentration are mg / L, and the unit for stirring time is h.

[0035] Calculate the increase in total nitrogen removal rate for the experimental group and the control group (without aluminum ions):

[0036] Increase in total nitrogen removal rate (%) = (Total nitrogen removal rate of experimental group after stirring - Total nitrogen removal rate of blank group after stirring) / Total nitrogen removal rate of blank group after stirring * 100%.

[0037] Example 1

[0038] This experiment used an SBR reactor with a reaction volume of 0.5L. A stirring device was installed above the reactor to ensure uniform mixing of the sludge and water. The effluent was manually drawn out using a syringe. Anaerobic ammonia oxidation granular sludge was inoculated into the reactor, and the aforementioned nitrogenous wastewater and aluminum solution were added. The influent ammonia nitrogen was controlled to be approximately 86 mg / L, nitrite nitrogen approximately 114 mg / L, and aluminum ion concentration 5 mg / L. The temperature was controlled at 30–33℃ using a water bath. The operating cycle included influent, stirring, sedimentation, idle, and effluent stages. Stirring was performed for 3.5 hours, after which the stirring device was turned off. One cycle was run daily for 9 days.

[0039] like Figure 2 , 4 As shown, compared with the case without aluminum ion addition, the total nitrogen removal rate increased by an average of 24.05%, successfully improving the nitrogen removal efficiency of anammox sludge.

[0040] Example 2

[0041] This experiment used an SBR reactor with a reaction volume of 0.5L. A stirring device was installed above the reactor to ensure uniform mixing of the sludge and water. The effluent was manually drawn out using a syringe. Anaerobic ammonia oxidation granular sludge was inoculated into the reactor, and the aforementioned nitrogenous wastewater and aluminum solution were added. The influent ammonia nitrogen was controlled at approximately 86 mg / L, nitrite nitrogen at approximately 114 mg / L, and aluminum ion concentration at 10 mg / L. The temperature was controlled at 30–33℃ using a water bath. The operating cycle included influent, stirring, sedimentation, idle, and effluent stages. Stirring was performed for 3.5 hours, after which the stirring device was turned off. One cycle was run daily for 9 days.

[0042] like Figure 2 , 4 As shown, compared with the case without aluminum ion addition, the total nitrogen removal rate increased by an average of 29.46%, successfully improving the nitrogen removal efficiency of anammox sludge.

[0043] Example 3

[0044] This experiment used an SBR reactor with a reaction volume of 0.5L. A stirring device was installed above the reactor to ensure uniform mixing of the sludge and water. The effluent was manually drawn out using a syringe. Anaerobic ammonia oxidation granular sludge was inoculated into the reactor, and the aforementioned nitrogenous wastewater and aluminum solution were added. The influent ammonia nitrogen was controlled at approximately 86 mg / L, nitrite nitrogen at approximately 114 mg / L, and aluminum ion concentration at 20 mg / L. The temperature was controlled at 30–33℃ using a water bath. The operating cycle included influent, stirring, sedimentation, idle, and effluent stages. Stirring was performed for 3.5 hours, after which the stirring device was turned off. One cycle was run daily for 9 days.

[0045] like Figure 2 , 4 As shown, compared with the case without aluminum ion addition, the total nitrogen removal rate increased by an average of 36.91%, successfully improving the nitrogen removal efficiency of anammox sludge.

[0046] Example 4

[0047] This experiment used an SBR reactor with a reaction volume of 0.5L. A stirring device was installed above the reactor to ensure uniform mixing of the sludge and water. The effluent was manually drawn out using a syringe. Anaerobic ammonia oxidation granular sludge was inoculated into the reactor, and the aforementioned nitrogenous wastewater and aluminum solution were added. The influent ammonia nitrogen was controlled at approximately 92 mg / L, nitrite nitrogen at approximately 109 mg / L, and aluminum ion concentration at 10 mg / L. The temperature was controlled at 30–35℃ using a water bath. The operating cycle included influent, stirring, sedimentation, idle, and effluent stages. Stirring was performed for 3.5 hours, after which the stirring device was turned off. One cycle was run daily for 45 days.

[0048] like Figure 1 , 3 As shown, compared with the case without aluminum ion addition, the total nitrogen removal rate increased by an average of 40.98%, successfully improving the nitrogen removal efficiency of anammox sludge.

[0049] Comparative Example 1

[0050] This experiment used an SBR reactor with a reaction volume of 0.5L. A stirring device was installed above the reactor to ensure uniform mixing of the sludge and water. The effluent was manually drawn out using a syringe. Anaerobic ammonia oxidation granular sludge was inoculated into the reactor, and the aforementioned nitrogenous wastewater was added. The influent ammonia nitrogen was controlled to be approximately 86 mg / L, and the nitrite nitrogen to be approximately 114 mg / L. The temperature was controlled at 30–33°C using a water bath. The operating cycle included influent, stirring, sedimentation, idle, and effluent stages. Stirring was performed for 3.5 hours, after which the stirring device was turned off. This experiment served as a control group for other embodiments, running one cycle per day for 9 days.

[0051] Counterexample 1

[0052] This experiment used an SBR reactor with a reaction volume of 0.5L. A stirring device was installed above the reactor to ensure uniform mixing of the sludge and water. The effluent was manually drawn out using a syringe. Anaerobic ammonia oxidation granular sludge was inoculated into the reactor. The aforementioned nitrogenous wastewater and aluminum solution were added to the reactor, controlling the influent ammonia nitrogen to approximately 92 mg / L, nitrite nitrogen to approximately 109 mg / L, and aluminum ion concentrations to 0, 30, 50, and 100 mg / L. The temperature was controlled at 30–35℃ using a water bath. The operating cycle included influent, stirring, sedimentation, idle, and effluent stages. Stirring was performed for 3.5 hours, after which the stirring device was turned off. One cycle was run daily for 45 days.

[0053] like Figure 1 , 3 As shown, compared to the case without aluminum ion addition, when the aluminum ion concentration was 30 mg / L, the total nitrogen removal rate decreased by an average of 35.02%, which had a certain inhibitory effect on anaerobic ammonia oxidation; when the aluminum ion concentration was 50 mg / L, compared to the case without aluminum ion addition, the total nitrogen removal rate decreased by an average of 72.95%, and the inhibitory effect on anaerobic ammonia oxidation was further amplified; when the aluminum ion concentration was 100 mg / L, compared to the case without aluminum ion addition, the total nitrogen removal rate decreased by an average of 94.96%, and the reactor was close to collapse.

[0054] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for improving the total nitrogen removal rate of anammox granular sludge using aluminum ions, characterized in that, Includes the following steps: (1) Inoculate the reactor with anaerobic ammonia oxidation granular sludge; (2) Add wastewater and aluminum solution to the reactor and stir during operation; (3) After the operation is completed, stop stirring, let the sludge settle and leave it idle, and wash the sludge with water before the operation on the second day; (4) Repeat steps (2) to (3) for 1 to 50 days; The reactor mentioned in step (1) is an anaerobic ammonia oxidation granular sludge sequencing batch reactor, and the temperature in the reactor is maintained at 30~35℃ and the dissolved oxygen concentration is 0.2~0.5 mg / L; In step (2), the concentration of aluminum ions in the reactor is 5~20 mg / L; In step (2), the aluminum salt in the aluminum solution is aluminum chloride hexahydrate.

2. The method for improving the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions according to claim 1, characterized in that, The stirring time in step (2) is 3.5 ± 0.5 hours.

3. The method for improving the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions according to claim 1, characterized in that, In step (1), the concentration of MLSS of the sludge inoculated in the reactor is 8200-8600 mg / L.

4. The method for improving the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions according to claim 1, characterized in that, In step (2), the influent substrate of the wastewater includes 2.581~2.601 g / L (NH4)2SO4, 3.241~3.261 g / L NaNO2, and 3.923~3.933 g / L NaHCO3, and the ammonia nitrogen concentration of the influent is controlled to be 80~110 mg / L and the nitrite nitrogen concentration is 100~120 mg / L.

5. The method for improving the total nitrogen removal rate of anaerobic ammonia oxidation granular sludge using aluminum ions according to claim 1, characterized in that, The anaerobic ammonia oxidation granular sludge mentioned in step (1) originated from a long-term stable UASB reactor and was acclimated in a laboratory SBR model. The acclimation conditions were as follows: The sludge is placed in a reactor, and 0.200~0.205 g / L (NH4)2SO4, 0.275~0.280 g / L NaNO2 and 0.311~0.312 g / L NaHCO3 are added. The sludge is acclimatized and cultured at room temperature. When the total nitrogen removal rate of the reactor stabilizes at over 70%, the sludge in the reactor is removed to obtain the anaerobic ammonia oxidation granular sludge.

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