Method and system for purifying ammonia-nitrogen wastewater by oyster shell reinforced photosynthetic microorganisms

Abstract

The application discloses a method and system for purifying ammonia-nitrogen wastewater by using oyster shell reinforced photosynthetic microorganisms. Seed liquid is obtained by culturing and enriching Rhodopseudomonas palustris, Rhodospirillum profundum, Sulfurspirochaeta shaposhnikovii and Rhodopseudomonas coprophila, and the above photosynthetic microorganisms are used as the core for purifying ammonia-nitrogen wastewater. The photosynthesis of the photosynthetic microorganisms absorbs light energy, converts the light energy into chemical energy, reduces the ammonia-nitrogen in the wastewater into inorganic nitrogen gas by using the chemical energy, and fixes CO2 in the air into biological organic matter, so that the removal of ammonia-nitrogen in the wastewater and the growth and reproduction of the photosynthetic microorganisms are realized. In the application, the photosynthetic microorganisms are used for denitrification, the carbon source input cost in the ammonia-nitrogen wastewater treatment process is greatly reduced, the discarded oyster shell is used as a biological carrier, the pH value of the wastewater can be corrected and CO2 in the water body can be supplemented, and the photosynthetic microorganisms are provided with a favorable growth and reproduction environment and a denitrification environment, and meanwhile, the discarded oyster shell can be treated in a reduced amount.

Description

Technical Field

[0001] This invention belongs to the field of wastewater purification technology, specifically relating to a method and system for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms. Background Technology

[0002] With rapid economic development and improved living standards, my country's water resources are suffering from severe pollution from ammonia-nitrogen-containing wastewater, leading to increasingly serious eutrophication and frequent cyanobacterial blooms in rivers and lakes. The harm caused by ammonia-nitrogen wastewater to water bodies has become a global concern, making it essential to continuously explore more energy-efficient and effective wastewater treatment methods.

[0003] Compared with traditional physicochemical methods, biological nitrogen removal technology has attracted much attention from scholars at home and abroad due to its advantages such as energy saving, high efficiency, and less secondary pollution. Biological nitrogen removal technology mainly focuses on ammoniation, nitrification, and denitrification, using microorganisms to convert various nitrogen-containing compounds into nitrogen gas for removal. In recent years, biological nitrogen removal processes have matured and achieved good nitrogen removal effects, but limitations remain, including long process flows, large land area requirements, the need to maintain sufficient alkalinity and large amounts of organic carbon sources, and high operating and maintenance costs. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms. This method and system utilize photosynthetic microorganisms as the core for purifying ammonia nitrogen wastewater. The microorganisms absorb light energy through photosynthesis, converting it into chemical energy. This chemical energy is then used to reduce ammonia nitrogen in the wastewater to inorganic nitrogen gas and fix CO2 in the air into biological organic matter. This achieves the removal of ammonia nitrogen from the wastewater and the growth and reproduction of photosynthetic microorganisms, significantly reducing the input cost of carbon sources in biological denitrification. By introducing waste oyster shells as a carrier for photosynthetic microorganisms, the acidification of wastewater during ammonia nitrogen removal is simultaneously addressed. The CO2 concentration in the water body is also replenished, providing favorable environmental conditions for the growth, reproduction, and denitrification of photosynthetic microorganisms, thus improving their denitrification efficiency. Simultaneously, the volume of waste oyster shells is reduced.

[0005] The above-mentioned objectives of the present invention are achieved through the following technical solutions.

[0006] This invention first provides a method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms, comprising the following steps:

[0007] S1. Selection and compounding of photosynthetic microorganisms: Four types of photosynthetic bacteria were selected to purify ammonia nitrogen wastewater: Rhodopseudomonas palustris CGMCC 1.8929, Rhodopseudomonas rubrum CGMCC 1.5005, Rhodopseudomonas sauropodophyllum ACCC 19809, and Rhodopseudomonas fecalis CGMCC 1.2176. Each strain was cultured, enriched, and then compounded to obtain seed liquid.

[0008] S2. Wastewater quality and quantity adjustment: Ammonia nitrogen wastewater is transported to the equalization tank, and the pH value of the wastewater is adjusted to neutral using acid and alkali solutions. Suspended particles in the wastewater are removed using flocculants to obtain homogenized ammonia nitrogen wastewater, which is then stored in the equalization tank and transported to the biochemical reaction tank in a homogenized manner.

[0009] S3. Start-up of the biochemical reaction tank: Transfer the effluent from the equalization tank to the biochemical reaction tank until the maximum water treatment capacity of the biochemical reaction tank is reached. Close the inlet and outlet water pipes of the biochemical reaction tank, transfer the seed liquid to the biochemical reaction tank, and culture in a closed environment until the water quality meets the standards. This means that the biochemical reaction tank has been successfully started up.

[0010] S4. Oyster shell-enhanced photosynthetic microorganism purification of ammonia nitrogen wastewater: After the biochemical reaction tank is successfully started, oyster shells are suspended below the liquid surface of the biochemical reaction tank, and the inlet and outlet water pipes of the biochemical reaction tank are opened to carry out continuous purification treatment of ammonia nitrogen wastewater. The hydraulic retention time of ammonia nitrogen wastewater in the biochemical reaction tank is controlled to be 24h to 48h, and fresh seed liquid is added to the biochemical reaction tank every day.

[0011] S5. Sludge settling: The wastewater discharged from the biological reaction tank is transported to the sedimentation tank, and the hydraulic retention time in the sedimentation tank is controlled to be 4h to 8h to remove the sludge generated during the biological reaction.

[0012] S6. Water quality monitoring: The effluent from the sedimentation tank is transported to the effluent pool, and the water quality is automatically monitored by an in-situ water quality testing device to ensure that the wastewater meets the discharge standards. If the water quality in the effluent pool does not meet the standards, the wastewater in the effluent pool needs to be transported to the emergency pool. After the system recovers and stabilizes, it is transported back to the biochemical reaction tank for treatment.

[0013] Furthermore, in step S1, the concentration of the enrichment solution for each strain is not less than 10. 8 CFU / mL, the volume ratio of the enrichment solution was Rhodopseudomonas palustris CGMCC 1.8929: Rhodopseudomonas rubrum CGMCC 1.5005: Rhodopseudomonas sauris ACCC 19809: Rhodopseudomonas fecalith CGMCC 1.2176 = 3~5: 1~2: 1~2: 1~2.

[0014] Furthermore, the acid solution and alkaline solution mentioned in step S2 are hydrochloric acid solution and sodium hydroxide solution, respectively, and the flocculant is one or more of polyaluminum chloride, polyaluminum sulfate, polyferric chloride, and polyferric sulfate. After adjustment, the pH value of the ammonia nitrogen wastewater is between 7.0 and 9.0, and there are no obvious suspended particles.

[0015] Furthermore, in step S3, when the biochemical reaction tank is started, the seed liquid delivery rate is 0.3% to 0.5% of the maximum water volume that the biochemical reaction tank can treat, and the water quality meets the standard when the ammonia nitrogen concentration in the wastewater is less than 5 mg / L.

[0016] Furthermore, in step S4, the oyster shells are suspended 20cm to 50cm below the surface of the liquid in the biochemical reaction tank, and the daily replenishment of fresh seed liquid is 0.03% to 0.05% of the total water volume of the biochemical reaction tank.

[0017] The present invention also provides a system for purifying ammonia nitrogen wastewater by enhancing photosynthetic microorganisms using oyster shells, including a wastewater conditioning module, a biochemical denitrification module, and an effluent module.

[0018] Furthermore, the wastewater conditioning module includes a conditioning tank and a dosing room. The conditioning tank is divided into a front section and a rear section. The bottom of the front section of the conditioning tank is equipped with a stirrer for conditioning the wastewater quality, while the rear section is used for storing and regulating the water volume. The dosing room is equipped with acid storage tanks, alkali storage tanks, and flocculant storage tanks, each of which is connected to the front section of the conditioning tank via pipelines.

[0019] Furthermore, the biochemical denitrification module includes a microbial culture chamber, a biochemical reaction tank, and a sedimentation tank. The microbial culture chamber is equipped with four microbial culture tanks and one seed liquid storage tank. The four microbial culture tanks are connected to the seed liquid storage tank through pipes. The seed liquid storage tank is connected to the biochemical reaction tank through pipes. The biochemical reaction tank and the sedimentation tank are connected and interconnected through pipes. Ammonia nitrogen wastewater can flow by gravity from the biochemical reaction tank into the sedimentation tank.

[0020] Furthermore, the water outlet module includes an outlet pool and an emergency pool. The outlet pool is equipped with an in-situ water quality detection device, and its outlet is connected to the inlet of the emergency pool through a pipe. When the water quality in the outlet pool is abnormal, the connecting pipe needs to be opened to discharge the wastewater in the outlet pool into the emergency pool. The outlet of the emergency pool is connected to the inlet of the biochemical reaction pool through a pipe. The connecting pipe can be opened to discharge the wastewater in the emergency pool into the biochemical reaction pool after the system returns to normal.

[0021] In existing technologies, ammonia nitrogen removal from wastewater is typically achieved through microbial nitrification-denitrification. This process requires sufficient alkalinity and a large amount of organic carbon source, resulting in complex processes, large land areas, and high operating and maintenance costs. Photosynthetic microorganisms can utilize light energy to fix atmospheric CO2 and synthesize organic matter, providing the energy needed for biological nitrogen removal and significantly reducing the input of organic carbon sources. However, during ammonia nitrogen removal, the wastewater gradually becomes acidic, which is detrimental to the growth and reproduction of photosynthetic microorganisms.

[0022] This invention utilizes the photosynthesis of photosynthetic microorganisms to absorb light energy, converting it into chemical energy. This chemical energy is then used to reduce ammonia nitrogen in wastewater into inorganic nitrogen gas and fix CO2 in the air into biological organic matter, thereby achieving the removal of ammonia nitrogen from wastewater and the growth and reproduction of photosynthetic microorganisms.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) This invention effectively combines a variety of photosynthetic microorganisms and uses them as the core of the denitrification system. Using sunlight as energy and CO2 as carbon source, it removes ammonia nitrogen from wastewater, which greatly reduces the input cost of organic carbon source.

[0025] (2) Considering that the wastewater will gradually become acidified during the ammonia nitrogen removal process, which is not conducive to the growth and reproduction of photosynthetic microorganisms, this invention applies the resource utilization of waste oyster shells to the ammonia nitrogen wastewater purification system. The shells are suspended on the surface of the ammonia nitrogen wastewater and the pH value of the wastewater is corrected in a timely manner through acid-base reaction. At the same time, it is convenient to observe and replenish and replace the shells. The CO2 generated during the pH correction process can also be used as a carbon source for photosynthetic microorganisms to absorb and utilize. In addition, the oyster shells can also serve as a carrier for photosynthetic microorganisms to attach and grow, which helps to increase their biomass and further improve the denitrification efficiency. At the same time, the waste oyster shells are reduced in volume.

[0026] (3) The biological denitrification system provided by the present invention has a simple structure and is easy to operate, and can be widely used for the treatment of ammonia nitrogen wastewater. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a simplified structural diagram of a system for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms, as provided by the present invention.

[0029] Figure 2 This is a schematic flowchart of a method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms, provided by the present invention. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Rhodopseudomonas palustris CGMCC 1.8929, Rhodopseudomonas rubrum CGMCC 1.5005, and Rhodopseudomonas fecalith CGMCC 1.2176 were all purchased from the China General Microbiological Culture Collection Center.

[0032] *Exothiospira salicylides* ACCC 19809 was purchased from the China Agricultural Microbial Culture Collection Center.

[0033] Example 1

[0034] like Figure 1 As shown, a system for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms includes: a wastewater conditioning module, a biochemical denitrification module, and an effluent module.

[0035] The wastewater conditioning module includes a conditioning tank and a chemical dosing room. The conditioning tank is divided into a front section and a rear section. The bottom of the front section is equipped with a stirrer for conditioning the wastewater quality, while the rear section is used for storing and regulating the water volume. The chemical dosing room is equipped with acid storage tanks, alkali storage tanks, and flocculant storage tanks, which are used to store hydrochloric acid solution, sodium hydroxide solution, and polyaluminum chloride solution, respectively. Each storage tank is connected to the front section of the conditioning tank via pipelines.

[0036] The biochemical denitrification module includes a microbial culture chamber, a biochemical reaction tank, and a sedimentation tank. The microbial culture chamber is equipped with four microbial culture tanks and one seed liquid storage tank. The four microbial culture tanks are connected to the seed liquid storage tank through pipelines. The seed liquid storage tank is connected to the biochemical reaction tank through pipelines. The biochemical reaction tank and the sedimentation tank are connected and interconnected through pipelines. Ammonia nitrogen wastewater can flow by gravity from the biochemical reaction tank into the sedimentation tank.

[0037] The water outlet module includes an outlet pool and an emergency pool. The outlet pool is equipped with an in-situ water quality detection device, and its outlet is connected to the inlet of the emergency pool through a pipe. When the water quality in the outlet pool is abnormal, the connecting pipe needs to be opened to discharge the wastewater in the outlet pool into the emergency pool. The outlet of the emergency pool is connected to the inlet of the biochemical reaction pool through a pipe. The connecting pipe can be opened to discharge the wastewater in the emergency pool into the biochemical reaction pool after the system returns to normal.

[0038] Example 2

[0039] Screening of photosynthetic microbial compound ratios

[0040] Four types of photosynthetic bacteria, namely Rhodopseudomonas palustris CGMCC 1.8929, Rhodopseudomonas rubrum CGMCC 1.5005, Rhodopseudomonas sauris ACCC 19809, and Rhodopseudomonas fecalith CGMCC 1.2176, were enriched in different volume ratios to obtain seed solutions. The seed solutions were added to ammonia nitrogen wastewater at an inoculum of 10%. After 3 days of photosynthetic purification reaction, the ammonia nitrogen removal rate in the wastewater was measured, and the results are shown in Table 1.

[0041] Table 1 Results of Photosynthetic Microorganism Selection and Compounding

[0042]

[0043] As shown in Table 1, the seed liquid prepared by mixing Rhodopseudomonas palustris bacterial solution, Rhodopseudomonas rubrum bacterial solution, Rhodopseudomonas serrata bacterial solution, and Rhodopseudomonas fecalis bacterial solution in a volume ratio of 5:2:2:1 had the highest ammonia nitrogen removal rate of 93.80%.

[0044] Example 3

[0045] like Figure 2 As shown, a method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms includes the following steps:

[0046] S1. Selection and formulation of photosynthetic microorganisms: Four types of photosynthetic bacteria were selected to purify ammonia nitrogen wastewater: *Rhodopseudomonas palustris* CGMCC 1.8929, *Rhodopseudomonas rubrum* CGMCC 1.5005, *Rhodopseudomonas saprolegnia* ACCC 19809, and *Rhodopseudomonas fecalis* CGMCC 1.2176. Each strain was cultured and enriched to a bacterial concentration of 10... 8 CFU / mL, and a seed solution was prepared by mixing Rhodopseudomonas palustris bacterial solution: Rhodopseudomonas rubrum bacterial solution: Rhodopseudomonas serrata bacterial solution: Rhodopseudomonas foetida bacterial solution = 5:2:2:1.

[0047] S2. Wastewater quality and quantity adjustment: Ammonia nitrogen wastewater is transported to the equalization tank, and the pH value of the wastewater is adjusted to between 7.0 and 9.0 using hydrochloric acid solution and sodium hydroxide solution. Suspended particles in the wastewater are removed using 0.1% polyaluminum chloride solution to obtain homogenized ammonia nitrogen wastewater. The wastewater is stored in the equalization tank and then transported to the biochemical reaction tank in a homogenized manner.

[0048] S3. Start-up of the biochemical reaction tank: Transfer the effluent from the equalization tank to the biochemical reaction tank until the maximum treatment capacity of the biochemical reaction tank is reached. Close the inlet and outlet pipes of the biochemical reaction tank. Transfer the seed liquid to the biochemical reaction tank at 0.5% of the maximum treatment capacity of the biochemical reaction tank. After 15 days of closed cultivation, if the ammonia nitrogen concentration in the wastewater is lower than 5 mg / L, the biochemical reaction tank is successfully started.

[0049] S4. Oyster shell-enhanced photosynthetic microorganism purification of ammonia nitrogen wastewater: After the biochemical reaction tank is successfully started, oyster shells are suspended 20-50cm below the liquid surface of the biochemical reaction tank. The inlet and outlet pipes of the biochemical reaction tank are opened to carry out continuous purification treatment of ammonia nitrogen wastewater. The hydraulic retention time of ammonia nitrogen wastewater in the biochemical reaction tank is controlled to be 48h. Fresh seed liquid is added to the biochemical reaction tank daily at 0.05% of the water storage capacity.

[0050] S5. Sludge settling: The wastewater discharged from the biological reaction tank is transported to the sedimentation tank, and the hydraulic retention time in the sedimentation tank is controlled to be 4 hours to remove the sludge generated during the biological reaction.

[0051] S6. Water Quality Monitoring: The effluent from the sedimentation tank is transported to the effluent pool, where the water quality is automatically monitored by an in-situ water quality testing device to ensure that the wastewater meets discharge standards. If the water quality in the effluent pool does not meet the standards, the wastewater in the effluent pool needs to be transported to the emergency pool. After the system stabilizes, it is then transported back to the biochemical reaction tank for treatment.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms, characterized in that, Includes the following steps: S1. Selection and compounding of photosynthetic microorganisms: Four types of photosynthetic bacteria were selected to purify ammonia nitrogen wastewater: Rhodopseudomonas palustris CGMCC 1.8929, Rhodopseudomonas rubrum CGMCC 1.5005, Rhodopseudomonas salsa ACCC 19809, and Rhodopseudomonas fecalis CGMCC 1.2176. Each strain was cultured and enriched, and then compounded to obtain seed liquid. S2. Wastewater quality and quantity adjustment: Ammonia nitrogen wastewater is transported to the equalization tank, and the pH value of the wastewater is adjusted to neutral using acid and alkali solutions. Suspended particles in the wastewater are removed using flocculants to obtain homogenized ammonia nitrogen wastewater, which is then stored in the equalization tank and transported to the biochemical reaction tank in a homogenized manner. S3. Start-up of the biochemical reaction tank: Transfer the effluent from the equalization tank to the biochemical reaction tank until the maximum water treatment capacity of the biochemical reaction tank is reached. Close the inlet and outlet water pipes of the biochemical reaction tank, transfer the seed liquid to the biochemical reaction tank, and culture in a closed environment until the water quality meets the standards. This means that the biochemical reaction tank has been successfully started up. S4. Oyster shell-enhanced photosynthetic microorganism purification of ammonia nitrogen wastewater: After the biochemical reaction tank is successfully started, oyster shells are suspended below the liquid surface of the biochemical reaction tank, and the inlet and outlet water pipes of the biochemical reaction tank are opened to carry out continuous purification treatment of ammonia nitrogen wastewater. The hydraulic retention time of ammonia nitrogen wastewater in the biochemical reaction tank is controlled to be 24 h~48 h, and fresh seed liquid is added to the biochemical reaction tank every day. S5. Sludge settling: The wastewater discharged from the biological reaction tank is transported to the sedimentation tank, and the hydraulic retention time in the sedimentation tank is controlled to be 4 h to 8 h, so as to remove the sludge generated during the biological reaction process. S6. Water quality monitoring: The effluent from the sedimentation tank is transported to the effluent pool, and the water quality is automatically monitored by an in-situ water quality testing device to ensure that the wastewater meets the discharge standards. If the water quality in the effluent pool does not meet the standards, the wastewater in the effluent pool needs to be transported to the emergency pool. After the system recovers and stabilizes, it is transported back to the biochemical reaction tank for treatment.

2. The method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms according to claim 1, characterized in that, Step S1: The concentration of the enrichment solution for each strain should not be less than 10. 8 CFU / mL, the volume ratio of the enrichment solution was Rhodopseudomonas palustris CGMCC 1.8929: Rhodopseudomonas rubrum CGMCC 1.5005: Rhodopseudomonas sauris ACCC 19809: Rhodopseudomonas fecalith CGMCC 1.2176 = 3~5: 1~2: 1~2: 1~2.

3. The method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms according to claim 1, characterized in that, The acid and alkali solutions mentioned in step S2 are hydrochloric acid solution and sodium hydroxide solution, respectively. The flocculant is one or more of polyaluminum chloride, polyaluminum sulfate, polyferric chloride, and polyferric sulfate. After adjustment, the pH value of the ammonia nitrogen wastewater is between 7.0 and 9.

0.

4. The method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms according to claim 1, characterized in that, When the biochemical reaction tank is started in step S3, the seed liquid delivery rate is 0.3% to 0.5% of the maximum water volume that the biochemical reaction tank can treat. The water quality meets the standard when the ammonia nitrogen concentration in the wastewater is less than 5 mg / L.

5. The method for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms according to claim 1, characterized in that, In step S4, the oyster shells are suspended 20 cm to 50 cm below the surface of the liquid in the biochemical reaction tank, and the daily fresh seed liquid replenishment is 0.03% to 0.05% of the total water volume of the biochemical reaction tank.

6. A system for purifying ammonia nitrogen wastewater using oyster shell-enhanced photosynthetic microorganisms according to any one of claims 1 to 5, characterized in that, The system includes a wastewater conditioning module, a biochemical denitrification module, and an effluent module. The wastewater conditioning module includes a conditioning tank and a dosing room. The conditioning tank is divided into a front section and a rear section. The bottom of the front section of the conditioning tank is equipped with a stirrer for adjusting the wastewater quality, and the rear section of the conditioning tank is used for storing and regulating the water volume. The dosing room is equipped with an acid storage tank, an alkali storage tank, and a flocculant storage tank. Each storage tank is connected to the front section of the conditioning tank through pipelines. The biochemical denitrification module includes a microbial culture chamber, a biochemical reaction tank, and a sedimentation tank. The microbial culture chamber is equipped with four microbial culture tanks and one seed liquid storage tank. The four microbial culture tanks are connected to the seed liquid storage tank through pipes. The seed liquid storage tank is connected to the biochemical reaction tank through pipes. The biochemical reaction tank and the sedimentation tank are connected and interconnected through pipes. Ammonia nitrogen wastewater can flow by gravity from the biochemical reaction tank into the sedimentation tank. The water outlet module includes an outlet pool and an emergency pool. The outlet pool is equipped with an in-situ water quality testing device. Its outlet is connected to the inlet of the emergency pool through a pipe. The outlet of the emergency pool is connected to the inlet of the biochemical reaction pool through a pipe.

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