A method for quickly starting a short-cut nitrification-anaerobic ammonium oxidation process

Abstract

A method for quickly starting a shortcut nitrification-anaerobic ammonia oxidation process, including grinding brucite into an equivalent particle size of less than 2mm, attaching it to or embedding it on a non-woven carrier by rolling or pressing, obtaining a brucite carrier, configuring a sludge suspension using conventional sludge from a sewage treatment plant, placing the carrier in the sludge suspension to complete pre-inoculation, and introducing the sludge suspension after pre-inoculation into a shortcut nitrification tank. Continuous aeration is cultivated for 2 to 7 days, and the aeration is stopped and allowed to stand for 6 to 24 hours. After sedimentation and drainage are performed in sequence, tap water or treated sewage is introduced, and the aeration is repeated for 12 to 48 hours. The process of standing and aeration is repeated at least once. The method of the present invention significantly shortens the screening time for nitrite oxidizing bacteria, shortens the establishment period of shortcut nitrification, improves the startup efficiency of shortcut nitrification process, and the method is suitable for the rapid establishment of shortcut nitrification system in winter, and improves the enrichment rate of ammonia oxidizing bacteria under low temperature conditions to a certain extent.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial water treatment, and particularly relates to a method for quickly starting a short-range nitrification-anaerobic ammonium oxidation process. Background Art

[0002] The ammonia nitrogen pollution situation in my country is becoming increasingly serious, and the environmental problems caused by this have attracted great attention from all parties, especially in the field of sewage denitrification. Traditional denitrification technologies have been unable to meet higher treatment requirements. Anaerobic ammonia oxidation (ANAMMOX), as a shortcut reaction for nitrification denitrification, has broken through the basic theory of traditional nitrification-denitrification, shortened the reaction path, and saved the cost expenditure caused by operations such as adding external carbon sources and chemical neutralizers. It has always been considered an efficient, economical and sustainable denitrification path. The technical advantages of ANAMMOX denitrification include: 1) High denitrification efficiency. With the same amount of sludge and the same volume, ANAMMOX can increase the denitrification load by several times compared with traditional nitrification-denitrification; 2) Low aeration energy consumption, because ANAMMOX removes ammonia nitrogen and nitrate nitrogen under anaerobic conditions. Therefore, only part of the ammonia nitrogen in the sewage is oxidized into nitrite nitrogen to meet the needs of the denitrification process; 3) The sludge production is low. Since anaerobic ammonia oxidation is an autotrophic denitrification process, the sludge yield is much lower than that of traditional denitrification processes such as nitrification and denitrification; 4) No external carbon source is required. For wastewater with a low C / N ratio, traditional denitrification processes must supplement carbon sources to meet the denitrification process. Anaerobic ammonia oxidizing bacteria, as autotrophic bacteria, do not require an external carbon source, and the carbon consumption of the entire system is much less than that of traditional denitrification processes.

[0003] Due to the technical characteristics of ANAMMOX denitrification, all ANAMMOX-based processes must be coupled with a short-cut nitrification reaction (PN) to partially convert the ammonia nitrogen in the wastewater into nitrite nitrogen. This coupling method is mainly divided into two categories: a two-stage separation or a single-stage short-cut nitrification-ANAMMOX system. For most mainstream wastewater treatment with low ammonia nitrogen, low free ammonia concentrations make it difficult to enrich ammonia oxidizing bacteria (AOB) and inhibit the activity of nitrite oxidizing bacteria (NOB). Therefore, low ammonia nitrogen concentrations can easily undermine the stability of the short-cut nitrification-ANAMMOX process. As a result, the existing ANAMMOX-based denitrification process has poor stability and low shock resistance, making it difficult to effectively treat low-concentration ammonia nitrogen wastewater.

[0004] Therefore, how to effectively combine the short-cut nitrification process and the anaerobic ammonium oxidation process and improve the stability of the short-cut nitrification-anaerobic ammonium oxidation process has become the main technical difficulty of this engineering application. Summary of the Invention

[0005] In order to solve the deficiencies in the prior art, the object of the present invention is to provide a method for quickly starting a short-cut nitrification-anaerobic ammonium oxidation process, so as to quickly start the short-cut nitrification and improve the stability of the short-cut nitrification-anaerobic ammonium oxidation process.

[0006] The present invention provides a method for quickly starting a short-range nitrification-anaerobic ammonium oxidation process, comprising:

[0007] Grinding brucite to obtain brucite crumbs, wherein the brucite crumbs have an equivalent particle size of less than 2 mm;

[0008] The brucite particles are attached to or embedded in the surface or inside of the non-woven fabric carrier by pressing or rolling, and the non-woven fabric is used as a support, and the brucite particles are evenly cross-linked in the middle to obtain a characteristic carrier with brucite attached;

[0009] The sludge suspension is prepared using the sludge from the sewage treatment plant, and the characteristic carrier attached with brucite is placed in the sludge suspension to complete the pre-inoculation;

[0010] The pre-inoculated sludge suspension is introduced into the short-cut nitrification tank and continuously aerated for 2 to 7 days. During the continuous aeration period, the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L.

[0011] After stopping aeration, let it stand for 6 to 24 hours, and then let it settle and drain. Then, introduce tap water or sewage to be treated and aerate again for 12 to 48 hours. During the aeration period, the dissolved oxygen concentration in the short-cut nitrification tank should be kept above 6 mg / L.

[0012] Repeat the process of stopping aeration and then standing for 6 to 24 hours, performing sedimentation and drainage in sequence, introducing tap water or sewage to be treated, and aerating again for 12 to 48 hours, wherein the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L at least once during the re-aeration period.

[0013] In one implementation, in the process of attaching or embedding the brucite granules onto the surface or inside of the non-woven fabric carrier by pressing or rolling, a tablet press or a roller press is used.

[0014] In one implementation, the magnesium hydroxide content in the brucite is higher than 85%.

[0015] In one implementation, the brucite adhesion mass per unit area of the characteristic carrier surface of the brucite is 0.1 g / cm 2 above.

[0016] In one implementation, before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further includes:

[0017] Tap water or sewage to be treated is sprayed on the non-woven fabric carrier, wherein the total mass of the sprayed tap water or sewage to be treated is less than the total mass of the attached brucite.

[0018] In one implementation, before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further includes:

[0019] The brucite particles are prepared into a brucite suspension with a water content of less than 90%, and the brucite suspension is sprinkled on the surface of the non-woven fabric carrier.

[0020] In one implementation, before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further includes:

[0021] Adding sewage treatment plant sludge with a moisture content of less than 80% to the brucite particles;

[0022] Among them, the mass ratio of the added mass of sewage treatment plant sludge to the mass of brucite particles is 1:10 to 1:1;

[0023] Brucite particles mixed with sewage treatment plant sludge were attached to the surface of a non-woven carrier.

[0024] In one implementation, before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further includes:

[0025] Magnesium hydroxide powder or calcium carbonate powder is added to the brucite granules, wherein the mixing ratio is not higher than 10% of the total mass of the brucite granules.

[0026] In one implementation, the sludge concentration (MLSS) of the sludge suspension is above 3000 mg / L.

[0027] The beneficial effect of the present invention is that, compared with the existing technology, it greatly shortens the screening time for nitrite-oxidizing bacteria, shortens the establishment period of short-term nitrification, and improves the startup efficiency of the short-term nitrification process. The existing short-term nitrification startup method usually requires the water temperature to be above 20°C, and the corresponding startup period is often more than 14 days. At the same time, a large amount of reagents need to be added to improve the startup effect, which invisibly increases the startup and operating costs, and the final effect established is difficult to maintain for a long time. The present invention mainly increases the implantation rate of sludge on the carrier by adding additional attachment materials, improves the biofilm formation and growth efficiency of ammonia-oxidizing bacteria, and at the same time limits the growth of nitrite-oxidizing bacteria, thereby quickly starting the short-term nitrification process. This method can still take effect quickly at 10-15°C, shortening the startup period by more than 50% compared with traditional processes. At the same time, this method is suitable for the rapid establishment of short-term nitrification systems in winter, and can also improve the enrichment rate of ammonia-oxidizing bacteria under low-temperature conditions to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram showing the change of ammonia nitrogen inlet and outlet concentrations over time in a short-range nitrification zone provided by an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the change of nitrite nitrogen inlet and outlet water concentration over time in a short-range nitrification zone provided by an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the change of nitrate nitrogen inlet and outlet water concentration over time in a short-range nitrification zone provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present application.

[0032] In the prior art, a short-cut nitrification-anaerobic ammonium oxidation process is used to treat low-ammonia nitrogen sewage, for example, in the treatment of municipal sewage. Generally, the screening time of nitrite-oxidizing bacteria is slow, the establishment cycle of short-cut nitrification is long, and the startup efficiency of short-cut nitrification is low. An embodiment of the present invention provides a method for quickly starting a short-cut nitrification-anaerobic ammonium oxidation process, comprising steps S1 to S.

[0033] S1. Grind brucite to obtain brucite particles, and attach the brucite particles to the surface of a non-woven fabric carrier to obtain a brucite carrier.

[0034] Brucite, primarily composed of magnesium hydroxide, is a naturally occurring mineral with a high magnesium content. Brucite is typically flaky or fibrous, with a large specific surface area. In the embodiments of the present invention, the flaky or fibrous brucite is first ground to produce brucite granules. In some preferred embodiments, the magnesium hydroxide content of the brucite exceeds 85%, and the alkalinity within the region is maintained by the release of alkalinity from the brucite.

[0035] In some preferred embodiments, the equivalent particle size of the ground brucite particles is below 2 mm, which increases the specific surface area of the brucite and improves the implantation rate of the sludge on the carrier.

[0036] After obtaining the brucite particles, the brucite particles are attached to the surface of a non-woven fabric carrier to obtain a characteristic carrier with brucite attached, wherein the brucite adhesion mass per unit area of the non-woven fabric surface of the characteristic carrier with brucite attached is 0.1 g / cm 2 The above ensures the adhesion of brucite on the surface of the non-woven fabric and increases the adhesion of subsequent sludge.

[0037] In some feasible methods, the brucite particles are attached to or embedded in the surface or interior of a non-woven fabric carrier by pressing or rolling using a tablet press or roller press. The non-woven fabric is used as a support, and the brucite particles are evenly cross-linked in the middle to ensure that the attachment surface is as uniform as possible, thereby obtaining a characteristic carrier for attaching brucite.

[0038] In some feasible methods, in order to achieve a better adhesion effect of brucite, tap water or sewage to be treated is sprayed on the non-woven fabric carrier, wherein the total mass of the sprayed tap water or sewage to be treated is less than the total mass of the attached brucite, and then the brucite particles are attached to the surface of the non-woven fabric carrier.

[0039] In some achievable methods, the brucite granules are attached to the surface of the non-woven fabric carrier by rolling or pressing, so as to ensure that the attachment surface is as uniform as possible.

[0040] In some feasible methods, brucite particles are first prepared into a brucite suspension with a moisture content of less than 90%, and then the brucite suspension is evenly sprinkled on the surface of the non-woven fabric carrier to achieve coating and bonding.

[0041] In one feasible approach, sewage treatment plant sludge with a moisture content of less than 80% is first added to the brucite granules. The mass ratio of the added sewage treatment plant sludge to the brucite granules is 1:10 to 1:1, preferably conventional sludge from municipal sewage treatment plants. The brucite granules mixed with the sewage treatment plant sludge are then attached to the surface of a non-woven fabric carrier. Pre-coating the non-woven fabric carrier with the brucite granules mixed with sludge increases the amount of sludge attached due to the surface particles and biofilm structure. This increased sludge content leads to a higher base number of ammonia-oxidizing bacteria, thus shortening startup time.

[0042] In some feasible embodiments, after the brucite granules are ground to obtain the brucite granules, magnesium hydroxide powder or calcium carbonate powder is added to the brucite granules to improve the subsequent adhesion effect, wherein the addition ratio is no more than 10% of the total mass of the brucite granules.

[0043] S2. Use conventional sludge from a sewage treatment plant to prepare a sludge suspension, and place the brucite carrier into the sludge suspension to complete pre-inoculation.

[0044] In the embodiment of the present invention, conventional sludge from a municipal sewage treatment plant is selected as inoculated sludge, and a sludge suspension having a sludge concentration MLSS of 3000 mg / L or higher is prepared. The brucite carrier treated in the above step is placed in the suspension to complete pre-inoculation.

[0045] S3. The pre-inoculated sludge suspension is introduced into the short-cut nitrification tank and continuously aerated and cultivated for 2 to 7 days. During the continuous aeration period, the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L.

[0046] The pre-inoculated sludge suspension is introduced into the short-cut nitrification tank without adding other substrates, and is continuously aerated and cultivated for 2 to 7 days, preferably, for 7 days. During the continuous aeration period, the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L.

[0047] S4. After stopping aeration, let it stand for 6 to 24 hours, carry out sedimentation and drainage in turn, then introduce tap water or sewage to be treated, and aerate again for 12 to 48 hours. During the re-aeration period, the dissolved oxygen concentration in the short-range nitrification tank is maintained above 6 mg / L.

[0048] Preferably, in the embodiment of the present invention, after the continuous aeration is stopped, the tank is left to stand for 12 hours to allow the short-cut nitrification tank to settle and separate the solid and liquid, and then the sewage is discharged. The tank is then replaced with tap water or sewage to be treated, and aerated again for 24 hours. During the re-aeration period, the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L.

[0049] S5. Repeat the steps of stopping aeration, allowing the tank to stand for 6 to 24 hours, performing sedimentation and drainage in sequence, introducing tap water or treated sewage, and aerating the tank again for 12 to 48 hours, wherein the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L at least once during the aeration step.

[0050] Repeat the above step S4 at least once. For example, after aeration for 24 hours again, let it stand for 12 hours, and then, after sedimentation and drainage, introduce the sewage to be treated, and then aerate again for 24 hours.

[0051] The following examples will further illustrate the present invention.

[0052] Example 1

[0053] Brucite, which contains 90% magnesium hydroxide, was ground into granules with equivalent particle sizes of less than 2 mm, 2 to 4 mm, and greater than 4 mm, yielding three groups of brucite granules with different particle sizes. A small amount of target wastewater to be treated was then sprayed onto a traditional non-woven fabric carrier, where the total mass of the target wastewater was less than the total mass of the brucite to be attached. The ground brucite granules were then rolled onto the surfaces of the three identical carriers to yield brucite carriers. The brucite adhesion mass per unit area of the three carrier groups reached 0.1 g / cm. 2 The carrier was then placed in a short-range nitrification tank and removed after 24 hours. After sun drying, the changes in the adhesion quality of brucite on the carrier were compared.

[0054] The results showed that the mass of brucite removed from carriers with particle sizes below 2 mm after immersion was approximately 82% of its original mass, while the mass of brucite removed from carriers with particle sizes of 2-4 mm and 4 mm or larger was only 56% and 41% of its original mass, respectively. This suggests a strong correlation between brucite particle size and adhesion performance.

[0055] Example 2

[0056] Brucite, which is composed of 90% magnesium hydroxide, is ground into granules with an equivalent particle size of less than 2mm to obtain brucite granules. A small amount of target wastewater to be treated is then sprayed onto a conventional non-woven fabric carrier, where the total mass of the target wastewater is less than the total mass of the brucite to be attached. The ground brucite granules are then adhered to the carrier surface by roller pressing to obtain a characteristic carrier for brucite attachment, with the brucite adhesion mass per unit area of the carrier reaching 0.1g / cm 2 The above. Then prepare the conventional sludge from the municipal sewage treatment plant as the inoculating sludge, configure it into a sludge suspension with an MLSS concentration of more than 3000 mg / L in the short-cut nitrification tank, and then place the prepared brucite carrier into the suspension to complete the pre-inoculation process. Thereafter, continuously aerate and cultivate for 3 days without adding any substrate to ensure that the dissolved oxygen in the water is always above 6 mg / L during aeration. After completing the continuous aeration process, stop aeration for 12 hours, then replace the sewage in the short-cut nitrification tank with the sewage to be treated, and aerate again for 24 hours to ensure that the dissolved oxygen in the water is always above 6 mg / L during aeration.

[0057] Application effect of embodiment 2

[0058] The method of Example 2 of the present invention is applied to the short-cut nitrification-anaerobic ammonium oxidation process. When the ambient temperature is between 8 and 15°C in winter, the initial temperature of the short-cut nitrification tank is lower than 15°C, and the short-cut nitrification process can be directly and quickly established. Figure 1 、 Figure 2 and Figure 3 The data indicates that ammonia nitrogen in the water was effectively treated. Although the shortened hydraulic retention time (HRT) reduced the aeration cycle in the short-range nitrification zone to some extent, it consistently ensured that approximately 40-60% of ammonia nitrogen was converted into nitrite nitrogen. On the other hand, the concentration of nitrate nitrogen did not increase significantly, demonstrating that the system successfully completed the short-range nitrification process under low and stable conditions, and achieved ideal startup results quickly even during the low temperatures of winter when activity is low.

[0059] The beneficial effect of the present invention is that, compared with the existing technology, it greatly shortens the screening time for nitrite-oxidizing bacteria, shortens the establishment period of short-term nitrification, and improves the startup efficiency of the short-term nitrification process. The existing short-term nitrification startup method usually requires the water temperature to be above 20°C, and the corresponding startup period is often more than 14 days. At the same time, a large amount of reagents need to be added to improve the startup effect, which invisibly increases the startup and operating costs, and the final effect established is difficult to maintain for a long time. The present invention mainly increases the implantation rate of sludge on the carrier by adding additional attachment materials, improves the biofilm formation and growth efficiency of ammonia-oxidizing bacteria, and at the same time limits the growth of nitrite-oxidizing bacteria, thereby quickly starting the short-term nitrification process. This method can still take effect quickly at 10-15°C, shortening the startup period by more than 50% compared with traditional processes. At the same time, this method is suitable for the rapid establishment of short-term nitrification systems in winter, and can also improve the enrichment rate of ammonia-oxidizing bacteria under low-temperature conditions to a certain extent.

[0060] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation plans of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, and is not a limitation on the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for quickly starting a short-cut nitrification-anaerobic ammonium oxidation process, characterized in that: include: Grinding brucite to obtain brucite crumbs, wherein the brucite crumbs have an equivalent particle size of less than 2 mm; The brucite particles are attached to or embedded in the surface or inside of the non-woven fabric carrier by pressing or rolling, and the non-woven fabric is used as a support, and the brucite particles are evenly cross-linked in the middle to obtain a characteristic carrier with brucite attached; Before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further comprises: Sewage treatment plant sludge with a moisture content of less than 80% is added to the brucite granules, wherein the mass ratio of the added sewage treatment plant sludge to the brucite granules is 1:10 to 1:1, and the brucite granules mixed with the sewage treatment plant sludge are attached to the surface of a non-woven fabric carrier; Before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further includes: preparing the brucite particles into a brucite suspension having a moisture content of less than 90%, and pouring the brucite suspension onto the surface of the non-woven fabric carrier; The sludge suspension is prepared using the sludge from the sewage treatment plant, and the characteristic carrier attached with brucite is placed in the sludge suspension to complete the pre-inoculation; The pre-inoculated sludge suspension is introduced into the short-cut nitrification tank and continuously aerated for 2 to 7 days. During the continuous aeration period, the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L. After stopping aeration, let it stand for 6 to 24 hours, allow sedimentation and drainage to proceed, then introduce tap water or untreated sewage and aerate again for 12 to 48 hours. During the aeration period, the dissolved oxygen concentration in the short-cut nitrification tank should be maintained above 6 mg / L. Repeat the process of stopping aeration and then standing for 6 to 24 hours, performing sedimentation and drainage in sequence, introducing tap water or sewage to be treated, and aerating again for 12 to 48 hours, wherein the dissolved oxygen concentration in the short-cut nitrification tank is maintained above 6 mg / L at least once during the re-aeration period.

2. The method for quickly starting a shortcut nitrification-anaerobic ammonium oxidation process according to claim 1, wherein: In the process of making the brucite granules adhere to or embed on the surface or inside of the non-woven fabric carrier by pressing or rolling, a tablet press device or a roller press device is used.

3. The method for quickly starting a shortcut nitrification-anaerobic ammonium oxidation process according to claim 1, wherein: The magnesium hydroxide accounts for more than 85% in the brucite.

4. The method for quickly starting a shortcut nitrification-anaerobic ammonium oxidation process according to claim 1, wherein: The brucite adhesion mass per unit area of the carrier surface is 0.1 g / cm 2 above.

5. The method for quickly starting a shortcut nitrification-anaerobic ammonium oxidation process according to claim 1, wherein: Before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further comprises: Tap water or sewage to be treated is sprayed on the non-woven fabric carrier, wherein the total mass of the sprayed tap water or sewage to be treated is less than the total mass of the attached brucite.

6. The method for quickly starting a shortcut nitrification-anaerobic ammonium oxidation process according to claim 1, wherein: Before the brucite particles are attached to or embedded in the surface or interior of the non-woven fabric carrier by pressing or rolling, the method further comprises: Magnesium hydroxide powder or calcium carbonate powder is added to the brucite granules, wherein the mixing ratio is not higher than 10% of the total mass of the brucite granules.

7. The method for quickly starting a shortcut nitrification-anaerobic ammonium oxidation process according to claim 1, wherein: The sludge concentration MLSS of the sludge suspension is above 3000 mg / L.

Images