A method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation.

Abstract

This invention discloses a method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation, belonging to the field of wastewater microbial treatment technology. It employs a coupling of nitrate dissimilatory reduction to ammonium, sulfur autotrophic denitrification, and anaerobic ammonia oxidation. The anaerobic ammonia oxidation reaction requires the supply of nitrite and ammonia nitrogen, while nitrate dissimilatory reduction (DNRA) can produce ammonia nitrogen, and sulfur autotrophic denitrification can accumulate nitrite nitrogen. Furthermore, the three processes require similar environmental conditions, and the substrate and products can complement each other well. Under anaerobic conditions, DNRA bacteria reduce nitrate to ammonia nitrogen, and sulfur autotrophic denitrifying bacteria reduce nitrate to nitrite. By controlling the ratio between sulfide and nitrate nitrogen (i.e., the sulfur-nitrogen molar ratio), the reaction type is guided, ensuring that the products are ammonia nitrogen and nitrite. Then, the anaerobic ammonia oxidation reaction occurs, achieving simultaneous removal of ammonia nitrogen and nitrite nitrogen. This method can increase the removal rate and removal load of ammonia nitrogen in wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater microbial treatment technology, specifically relating to a method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation. Background Technology

[0002] With the rapid development of my country's light industry, pharmaceuticals, petrochemicals, and other industries, many industrial wastewaters contain nitrogenous pollutants (mainly ammonia nitrogen) and sulfurous pollutants (mainly sulfates). In the biological treatment of these wastewaters, ammonia nitrogen can be converted into nitrates or nitrites, while sulfates can be converted into sulfides. Therefore, how to perform advanced treatment of these secondary pollutants before wastewater discharge is a very urgent issue.

[0003] In recent years, sulfur autotrophic denitrification processes using sulfur sources (such as sulfides) as electron donors have been extensively studied both domestically and internationally. Sulfides, as electron donors, eliminate the need for additional organic carbon sources to achieve autotrophic denitrification, significantly reducing investment and operating costs. Under the action of sulfur autotrophic denitrifying bacteria, nitrates, acting as electron acceptors, are preferentially reduced to nitrites and accumulated; this process is called sulfur autotrophic short-cut denitrification. The accumulated nitrites can then serve as substrates for anaerobic ammonium oxidation.

[0004] Furthermore, sulfur autotrophic denitrification is suitable for conditions with a low S / N ratio. However, some industrial wastewater containing large amounts of sulfides and nitrate nitrogen will undergo nitrate dissociation to ammonium (DNRA), a process in which nitrate nitrogen is converted to ammonium via nitrite. The reaction process involves NO3. - →NO2 - →NH4 + It can provide another reaction substrate for anaerobic ammonia oxidation. DNRA usually occurs when there is an excess of electron donors, such as carbon sources (organic matter) or excess reduced sulfur (sulfides). DNRA is often found in denitrification.

[0005] Anaerobic ammonium oxidation (ANAMMOX), an autotrophic nitrogen removal reaction using ammonia as the inorganic electron donor for nitrite denitrification, has become a research hotspot in the field of biological nitrogen removal in recent years due to its ability to significantly reduce the energy consumption of aerobic ammonium oxidation and the carbon source for denitrification. Its reaction formula is: NH4 + + 1.32NO2 - + 0.066HCO3 - + 0.13H + → 1.02N2+ 0.26NO3 - +0.066CH2O 0.5 + 2.03H2O.

[0006] Currently, there are many reports on the coupling of the above technologies in the field of wastewater treatment.

[0007] CN114772725A discloses a device and method for enhancing nitrogen and phosphorus removal from domestic sewage through sulfur autotrophic short-cut denitrification coupled with anaerobic ammonium oxidation. The method involves pumping the secondary treated effluent from a municipal wastewater treatment plant, with nitrate nitrogen as the main pollutant, and the effluent from an SBR (Self-Bio-Bio-Bio-Bio-Bio-Anaerobic Filter) into a sulfur autotrophic short-cut denitrification anaerobic ammonium oxidation biological filter in a proportional manner. Elemental sulfur in the sulfur granular filter media (composed of sulfur and siderite) is used as the electron donor, and autotrophic nitrogen removal is achieved through the sulfur autotrophic short-cut denitrification coupled with anaerobic ammonium oxidation pathway.

[0008] CN114105291A discloses a method for deep nitrogen removal based on biochar-enhanced dissimilatory nitrate reduction to ammonia coupled with anaerobic ammonia oxidation. By adding anaerobic ammonia oxidation granular sludge to the anaerobic ammonia oxidation reactor and adding biochar, the anaerobic ammonia oxidation reactor is used as the reaction site for water treatment. This method significantly enhances the coupling between DNRA metabolism of anaerobic ammonia oxidizing bacteria and the anaerobic ammonia oxidation reaction, and greatly improves the total nitrogen removal efficiency and carbon removal efficiency of the anaerobic ammonia oxidation system.

[0009] Because nitrate dissimilatory reaction, sulfur autotrophic denitrification, and sulfur-driven DNRA require similar environmental conditions, their substrates and products can complement each other well. If combined, nitrate dissimilatory reaction (DNRA) can produce ammonia nitrogen when the S / N ratio is high. As the reaction proceeds and the S / N ratio decreases, sulfur autotrophic denitrification can accumulate nitrite nitrogen, which can then undergo anaerobic ammonium oxidation, achieving simultaneous removal of ammonia nitrogen and nitrite nitrogen. However, no reports have yet been published on the coupling of these three reactions. Summary of the Invention

[0010] This invention provides a method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation. By coupling anaerobic ammonia oxidation, DNRA reaction, and sulfur autotrophic denitrification, a simultaneous biological denitrification and desulfurization process is developed, which can simultaneously remove sulfides and nitrates, and can increase the removal rate and removal load of ammonia nitrogen in wastewater.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A method for treating nitrogenous wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation is proposed. This method involves a coupled sulfur and nitrogen removal process: nitrate dissimilatory reduction to ammonia (DNRA) – sulfur autotrophic denitrification – anaerobic ammonia oxidation. Under anaerobic conditions, nitrate dissimilatory bacteria (DNRA) reduce nitrate to ammonia nitrogen in a biological system. Subsequently, sulfur autotrophic denitrifying bacteria reduce nitrate to nitrite. The reaction type is guided by controlling the ratio of sulfide to nitrate nitrogen (sulfur-nitrogen molar ratio), ensuring that the products are ammonia nitrogen and nitrite. The wastewater then enters an anaerobic ammonia oxidation (UASB) reactor for anaerobic ammonia oxidation, achieving simultaneous removal of ammonia nitrogen and nitrite nitrogen. The specific steps include:

[0013] (1) Sulfate autotrophic bacteria and DNRA bacteria are added to the anaerobic membrane bioreactor. The reactor is started up after 60-100 days of operation to achieve the coupling of DNRA with sulfur autotrophic denitrification.

[0014] (2) After startup, the wastewater to be treated is introduced into the anaerobic membrane bioreactor through two inlets. By controlling the flow rates of the sulfur-containing wastewater and the nitrogen-containing wastewater respectively, the ratio between sulfide and nitrate nitrogen in the reaction is controlled, so that DNRA bacteria reduce nitrate to ammonia nitrogen and sulfur autotrophic denitrifying bacteria reduce nitrate to nitrite.

[0015] (3) The effluent from the anaerobic membrane bioreactor enters the UASB reactor to undergo anaerobic ammonia oxidation reaction, thereby achieving efficient removal of nitrogen from the wastewater.

[0016] In the steps described above, step (1) involves mixing the two types of bacteria evenly and then adding them to the reaction zone of the anaerobic membrane bioreactor. Some of the added sulfur-oxidizing bacteria can only perform denitrification, while others can also undergo nitrate disequilibrium to produce ammonia nitrogen, but the amount produced is relatively small. Thioploca, Beggiatoa spp In addition, the added DNRA bacteria also include some iron bacteria; the added sulfur-oxidizing bacteria and DNRA bacteria are both 500 mg / L.

[0017] The anaerobic membrane bioreactor is a submerged anaerobic membrane bioreactor with two water inlets at the top and bottom. One inlet is for sulfur-containing wastewater and the other is for nitrogen-containing wastewater, both of which are fed into the anaerobic membrane bioreactor.

[0018] In step (2), the S / N molar ratio of the wastewater fed into the reactor is (1.5-3):1, preferably (1.8-2.5):1, to promote DNRA. After a certain amount of ammonia nitrogen is generated, the S / N is readjusted to (0-1):1 to promote sulfur autotrophic denitrification.

[0019] In step (2), adjust the temperature and pH to maintain the temperature at 25-30℃ and the pH at 7.0-8.5, and simultaneously enrich DNRA bacteria and sulfur autotrophic denitrifying bacteria.

[0020] In step (3), the NH4 in the effluent of the anaerobic membrane bioreactor + / NO2 - With a molar ratio of (1-1.4):1, the temperature and pH of the anaerobic ammonia oxidation (UASB) reactor are controlled to maintain the temperature at 25-35℃ and the pH at 7.0-8.5, thereby achieving efficient removal of nitrogen from wastewater.

[0021] The inlet, outlet, and exhaust pipes of the anaerobic membrane bioreactor and the anaerobic ammonia oxidation UASB reactor are all equipped with water seals to isolate oxygen and maintain an anaerobic environment.

[0022] Beneficial effects: This invention provides a method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation, which has the following advantages compared with the prior art:

[0023] 1. The method of the present invention adopts DNRA-sulfur autotrophic denitrification-anaerobic ammonium oxidation coupled denitrification. The anaerobic ammonium oxidation reaction requires the supply of nitrite and ammonia nitrogen, while the DNRA reaction can produce ammonia nitrogen, and sulfur autotrophic denitrification can accumulate nitrite nitrogen. Moreover, the environmental conditions required by the three are similar, and the substrate and product can complement each other well, which greatly improves the removal and load of ammonia nitrogen in the original wastewater and has obvious economic benefits.

[0024] 2. The present invention allows nitrogen-containing wastewater and sulfur-containing wastewater to be simultaneously introduced into an anaerobic membrane bioreactor. The operation is simple and no additional products are generated. It is economical and efficient, and sulfur autotrophic denitrification and DNRA can be achieved in the same environment, reducing the number of reactors and the floor space required.

[0025] 3. The method of the present invention operates under mild conditions and can be carried out at normal pressure without the need for specific conditions; moreover, no toxic or harmful substances are generated, and it is safe and harmless to the environment.

[0026] 4. The method of the present invention can accurately guide the reaction type and the yield of reaction products by reasonably controlling the ratio of the two types of influent. The operation method is simple and easy to implement. Due to the presence of DNRA, ammonia nitrogen does not need to be added to the influent of the anaerobic ammonia oxidation reactor, reducing the number of operation steps. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the device structure used in this embodiment of the invention to promote sulfur autotrophic denitrification and anaerobic ammonia oxidation for efficient nitrogen removal. In the figure, 1 is sulfur-containing wastewater, 2, 4, and 6 are peristaltic pumps, 3 is an anaerobic membrane bioreactor, 5 is nitrogen-containing wastewater, 7 is an anaerobic ammonia oxidation UASB reactor, and 8 is effluent.

[0028] Figure 2 This is a graph showing the effect of changes in sulfide concentration in the influent and effluent in Embodiment 1 of the present invention;

[0029] Figure 3 This is a graph showing the effect of changes in nitrate nitrogen concentration in the influent and effluent in Example 1 of the present invention;

[0030] Figure 4 This is a graph showing the effect of TN concentration changes in the influent and effluent in Embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments: Example 1

[0032] A method for efficiently treating nitrogen-containing wastewater based on nitrate dissimilatory reduction to ammonium combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation includes the following steps:

[0033] (1) As Figure 1 As shown, sulfur-oxidizing bacteria and DNRA bacteria were uniformly added to the reaction zone of the anaerobic membrane bioreactor. The bacterial strains were taken from a sulfur autotrophic reactor and a DNRA enrichment culture device that had been running for more than half a year. The anaerobic membrane bioreactor was a submerged anaerobic membrane bioreactor. The start-up time was 80 days, and the hydraulic retention time was 24 hours. The coupling of the two bacteria was successfully achieved in the reactor.

[0034] (2) Two influent streams are introduced from the bottom of the anaerobic membrane bioreactor: one stream of sulfur-containing wastewater and the other stream of nitrogen-containing wastewater (both originating from a leather manufacturing plant). Both streams are fed into the anaerobic membrane bioreactor. Under anaerobic conditions, the ratio of sulfide to nitrate nitrogen in the reaction, i.e., the sulfur-nitrogen molar ratio, is controlled by adjusting the flow rates at the two influent streams. This controls the reaction type and the yield of the reaction products. The reactor utilizes DNRA bacteria to reduce nitrate to ammonia nitrogen, and sulfur-autotrophic denitrifying bacteria to reduce nitrate to nitrite, controlling the products to be ammonia nitrogen and nitrite. After the reactor is started up, the water retention time remains constant, and the flow rates at the two influent streams are controlled to ensure that... The S / N molar ratio of the wastewater fed into the reactor is 2:1, initially promoting DNRA. After a certain amount of ammonia nitrogen is generated, the S / N molar ratio is readjusted to 0.5:1 to promote sulfur autotrophic denitrification. When the S / N ratio is too high, there are more electron donors and the redox potential is too low, which will inhibit sulfur autotrophic denitrifying bacteria but promote DNRA, so DNRA has an absolute advantage. When the S / N ratio is low, there are fewer electron donors and the redox potential is higher, at which point the sulfur autotrophic denitrification reaction has an absolute advantage. A constant temperature circulating water bath device is used to maintain the internal temperature of the anaerobic membrane bioreactor at 2661℃, and 0.5M HCl is used to adjust the pH to 7.86-0.2.

[0035] (3) Maintain a continuous effluent flow from the anaerobic membrane bioreactor, controlled by a level controller, to ensure that the effluent from the anaerobic membrane bioreactor contains NH4+. + / NO2 - The molar ratio was 1.3:1, and the solution flowed into the anaerobic ammonia oxidation (UASB) reactor. The temperature and pH were controlled to maintain the temperature at 3461℃ and the pH at 8.06-0.2. Finally, the combined denitrification reaction of DNRA, sulfur autotrophic denitrification and anaerobic ammonia oxidation was successfully achieved and operated stably, realizing the efficient removal of sulfur and nitrogen from wastewater.

[0036] The entire system runs continuously for 120 days, which can be divided into 6 phases, each lasting 20 days. Figure 2 The diagram shows the effect of sulfide removal in the influent and effluent. As can be seen from the diagram, the removal efficiency of sulfide is relatively low in the first three stages, but from the fourth stage onwards, the removal efficiency is significantly improved, and the final sulfide removal rate exceeds 90%. Figure 3 This is a diagram showing the influent and effluent effects of nitrate nitrogen treatment. Figure 4 The diagram shows the influent and effluent effects of TN. As can be seen from the diagram, the removal rates of both nitrate nitrogen and total nitrogen show a gradual upward trend from the first to the fourth stage, and tend to stabilize in the fourth and fifth stages. Ultimately, the nitrate nitrogen removal rate is around 95%, and the total nitrogen removal rate exceeds 90%. Example 2

[0037] The method for efficiently treating nitrogen-containing wastewater based on the dissimilatory reduction of nitrate to ammonium combined with denitrification coupled with anaerobic ammonia oxidation, as described in Example 1, differs in that:

[0038] Step (2) The initial S / N molar ratio of the anaerobic membrane bioreactor is 2.5:1. First, DNRA is promoted. After a certain amount of ammonia nitrogen is generated, the S / N is readjusted to 0.3:1 to promote sulfur autotrophic denitrification. A constant temperature circulating water bath device is used to maintain the internal temperature of the anaerobic membrane bioreactor at 2861℃. The pH is adjusted to 7.560.2 using 0.5M HCl.

[0039] Step (3) Maintain a continuous effluent flow from the anaerobic membrane bioreactor, controlled by a level controller, so that the effluent from the anaerobic membrane bioreactor contains NH4+. + / NO2 - The ratio is 1.1:1, and the mixture flows into the anaerobic ammonia oxidation (UASB) reactor. The temperature and pH are controlled to maintain the temperature at 3261℃ and the pH at 7.560.2.

[0040] The above are merely preferred embodiments of the present invention, which will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that for those skilled in the art, any modifications and improvements made without departing from the concept of the present invention are protected by the present invention.

Claims

1. A method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation, characterized in that, A coupled process of nitrate dissimilatory conversion to ammonium, sulfur autotrophic denitrification, and anaerobic ammonium oxidation is employed. Under anaerobic conditions, DNRA bacteria reduce nitrate to ammonia nitrogen, while sulfur autotrophic denitrifying bacteria reduce nitrate to nitrite. The reaction type is guided by controlling the ratio of sulfide to nitrate nitrogen (sulfur-nitrogen molar ratio) in stages. Initially, the S / N molar ratio of the wastewater entering the reactor is controlled at (1.8-2.5):1 to promote DNRA. After a certain amount of ammonia nitrogen is generated, the S / N molar ratio is adjusted to (0-1):1 to promote sulfur autotrophic denitrification, controlling the products to be ammonia nitrogen and nitrite. Then, the anaerobic ammonium oxidation reaction occurs, controlling the NH4+. + / NO2 - The molar ratio is (1-1.4):1, which enables the simultaneous removal of ammonia nitrogen and nitrite nitrogen.

2. The method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation according to claim 1, the method specifically includes the following steps: (1) Sulfate autotrophic bacteria and DNRA bacteria are added to the reaction zone of the anaerobic membrane bioreactor. The reactor is started up after 60-100 days of operation to achieve the coupling of DNRA with sulfur autotrophic denitrification. (2) After startup, the wastewater to be treated is introduced into the anaerobic membrane bioreactor through two inlets. The ratio between sulfide and nitrate nitrogen in the reaction is controlled by controlling the flow rates of sulfur-containing wastewater and nitrogen-containing wastewater respectively, so that the temperature is maintained at 25-35℃, the pH is maintained at 6.5-8.5, and the S / N molar ratio is controlled so that DNRA bacteria reduce nitrate to ammonia nitrogen. After a certain amount of ammonia nitrogen is generated, the S / N molar ratio is readjusted so that sulfur autotrophic denitrifying bacteria reduce nitrate to nitrite. (3) The effluent from the anaerobic membrane bioreactor enters the UASB reactor to undergo anaerobic ammonia oxidation reaction, thereby achieving efficient removal of nitrogen from the wastewater.

3. The method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation according to claim 2, characterized in that, The amount of sulfur autotrophic bacteria and DNRA bacteria added in step (1) is 500 mg / L.

4. The method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation according to claim 2, characterized in that, In step (2), the reactor temperature is 26-28℃ and the pH is 7.5-8.

5.

5. The method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation according to claim 2 or 4, characterized in that, In step (3), the temperature of the UASB reactor is maintained at 20-35℃ and the pH is maintained at 7.0-8.

5.

6. The method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation according to claim 2, characterized in that, The anaerobic membrane bioreactor is a submerged anaerobic membrane bioreactor and is connected in series with the UASB reactor.

7. The method for treating nitrogen-containing wastewater based on nitrate dissimilatory reduction combined with sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation according to claim 2, characterized in that, The inlet, outlet, and exhaust pipes of the anaerobic membrane bioreactor and the UASB reactor are all equipped with water seals to isolate oxygen and maintain an anaerobic environment.

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