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

Abstract

The invention discloses a method and a system for purifying ammonia-nitrogen wastewater by using oyster shell enhanced photosynthetic microorganisms. The method comprises the following steps: culturing and enriching rhodopseudomonas palustris, rhodospirillum rubrum, ectothiorhodospirillum shavicola and rhodopseudomonas faecalis, compounding to obtain a seed solution, taking the photosynthetic microorganism as a core for purifying ammonia nitrogen wastewater, absorbing light energy by utilizing photosynthesis of the photosynthetic microorganism, converting the light energy into chemical energy, and purifying the ammonia nitrogen wastewater. Ammonia nitrogen in the wastewater is reduced into inorganic nitrogen by chemical energy, and CO2 in the air is fixed into biological organic matters, so that the removal of the ammonia nitrogen in the wastewater and the growth and reproduction of photosynthetic microorganisms are realized. According to the method, the photosynthetic microorganisms are adopted for denitrification, the carbon source input cost in the ammonia-nitrogen wastewater treatment process is greatly reduced, the waste oyster shells are used as biological carriers, the pH value of the wastewater can be synchronously corrected, CO2 in a water body can be supplemented, a favorable growth, reproduction and denitrification environment is provided for the photosynthetic microorganisms, and meanwhile reduction treatment of the waste oyster shells is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater purification, and specifically relates to a method and a system for purifying ammonia nitrogen wastewater by strengthening photosynthetic microorganisms with oyster shells. Background Art

[0002] With the rapid economic development and the improvement of people's living standards, my country's water resources are suffering from a large amount of ammonia nitrogen wastewater pollution, and the eutrophication of water bodies is becoming increasingly serious, resulting in frequent outbreaks of blue algae in rivers and lakes. The harm caused by ammonia nitrogen wastewater to water bodies has become a global concern, and it is very necessary to continuously explore more energy-saving and efficient sewage purification methods.

[0003] Compared with traditional physical and chemical methods, biological denitrification technology has attracted much attention from scholars at home and abroad due to its advantages of energy saving, high efficiency, and less secondary pollution. Biological denitrification technology is mainly based on ammoniation, nitrification and denitrification. Under the action of microorganisms, various nitrogen-containing compounds are converted into nitrogen gas and removed. In recent years, the biological denitrification process has been continuously developed and has been close to maturity. It has a good denitrification effect, but it still has limitations such as long process flow, large land area, the need to ensure sufficient alkalinity and a large amount of organic carbon source, and high operation and maintenance costs. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for purifying ammonia nitrogen wastewater by strengthening photosynthetic microorganisms with oyster shells. The method and system use photosynthetic microorganisms as the core of purifying ammonia nitrogen wastewater, utilize photosynthesis of photosynthetic microorganisms to absorb light energy, convert light energy into chemical energy, utilize chemical energy to reduce ammonia nitrogen in wastewater to inorganic nitrogen gas and fix CO2 in air as biological organic matter, thereby achieving the removal of ammonia nitrogen in wastewater and the growth and reproduction of photosynthetic microorganisms, which can greatly reduce the input cost of carbon source in biological denitrification. By introducing discarded oyster shells as photosynthetic microorganism carriers, the problem of wastewater acidification in the process of ammonia nitrogen removal is solved simultaneously, and the CO2 concentration in the water body can be supplemented to provide favorable environmental conditions for the growth and reproduction of photosynthetic microorganisms and denitrification, thereby improving their denitrification efficiency and achieving the reduction of discarded oyster shells.

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

[0006] The present invention first provides a method for purifying ammonia nitrogen wastewater by strengthening photosynthetic microorganisms with oyster shells, comprising the following steps:

[0007] S1. Selection and compounding of photosynthetic microorganisms: Four types of photosynthetic bacteria, namely Rhodopseudomonas palustris CGMCC 1.8929, Rhodospirillum crimsonii CGMCC1.5005, Exothiospirillum sabori ACCC 19809, and Rhodopseudomonas faecalis CGMCC 1.2176, were selected to purify ammonia nitrogen wastewater. Each strain was cultured and enriched, and then compounded to obtain seed solution;

[0008] S2. Regulation of wastewater quality and quantity: transport the ammonia nitrogen wastewater to the regulating tank, adjust the pH value of the wastewater to neutral with acid and alkali, remove suspended particles in the wastewater with flocculants, obtain homogenized ammonia nitrogen wastewater, store it in the regulating tank, and transport it to the biochemical reaction tank in an evenly distributed manner;

[0009] S3, biochemical reaction pool cultivation start: the effluent from the regulating pool is transported to the biochemical reaction pool until the maximum water treatment capacity of the biochemical reaction pool is reached, the inlet and outlet pipes of the biochemical reaction pool are closed, the seed liquid is transported to the biochemical reaction pool, and the closed cultivation is carried out until the water quality meets the standard, which means that the biochemical reaction pool is successfully started;

[0010] S4. Oyster shells strengthen photosynthetic microorganisms to purify ammonia nitrogen wastewater: After the biochemical reaction tank is successfully started, oyster shells are hung below the liquid surface of the biochemical reaction tank, and the inlet and outlet pipes of the biochemical reaction tank are opened to continuously purify the ammonia nitrogen wastewater. The hydraulic retention time of the 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 sedimentation: The wastewater discharged from the biochemical reaction tank is transported to the sedimentation tank, and the hydraulic retention time in the sedimentation tank is controlled to be 4h~8h, and the sludge generated in the biochemical reaction process is removed by sedimentation;

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

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

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

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

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

[0017] The invention also provides a system for purifying ammonia nitrogen wastewater by using oyster shells to strengthen photosynthetic microorganisms, comprising a wastewater regulating module, a biochemical denitrification module and a water outlet module.

[0018] Furthermore, the wastewater regulation module includes a regulating tank and a dosing room. The regulating tank is divided into two parts: the front section and the back section. The bottom of the front section of the regulating tank is provided with an agitator for regulating the wastewater quality, and the back section of the regulating tank is used to store and regulate the water volume. The dosing room is provided with an acid storage tank, an alkali storage tank and a flocculant storage tank, and each storage tank is connected to the front section of the regulating tank through a pipeline.

[0019] Furthermore, the biochemical denitrification module includes a microbial culture room, a biochemical reaction tank and a sedimentation tank. The microbial culture room is provided with 4 bacterial culture tanks and 1 seed liquid storage tank. The 4 bacterial culture tanks are connected with the seed liquid storage tank through pipelines. The seed liquid storage tank is connected with the biochemical reaction tank through pipelines. The biochemical reaction tank and the sedimentation tank are interconnected through pipelines. Ammonia nitrogen wastewater can enter the sedimentation tank from the biochemical reaction tank by gravity.

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

[0021] In the prior art, the nitrification-denitrification of microorganisms is usually used to remove ammonia nitrogen from wastewater. During the denitrification process, sufficient alkalinity and a large amount of organic carbon source need to be ensured. The process is complicated, the land area is large, and the operation and maintenance costs are high. Photosynthetic microorganisms can use light energy to fix CO2 in the air to synthesize organic matter, which is used to provide the energy required in the biological denitrification process, greatly reducing the input of organic carbon sources. However, during the removal of ammonia nitrogen, the wastewater will gradually become acidic, which is not conducive to the growth and reproduction of photosynthetic microorganisms.

[0022] The present invention utilizes the photosynthesis of photosynthetic microorganisms to absorb light energy, converts the light energy into chemical energy, utilizes the chemical energy to reduce the ammonia nitrogen in the wastewater into inorganic nitrogen gas, and fixes CO2 in the air into biological organic matter, thereby achieving the removal of ammonia nitrogen in the 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) The present 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 a carbon source to achieve the removal of ammonia nitrogen in wastewater, greatly reducing the investment cost of organic carbon sources.

[0025] (2) Considering that the wastewater will gradually become acidic during the removal of ammonia nitrogen, which is not conducive to the growth and reproduction of photosynthetic microorganisms, the present invention applies the resource utilization of discarded oyster shells in the ammonia nitrogen wastewater purification system, suspends them on the surface of the ammonia nitrogen wastewater, and timely corrects the pH value of the wastewater through acid-base reaction, while facilitating observation and replenishment. The CO2 generated during the correction of the pH value of the wastewater can also be used as a carbon source for photosynthetic microorganisms to absorb and utilize. In addition, oyster shells can also be used as a carrier for photosynthetic microorganisms to attach and grow, which helps to increase their biomass, thereby further improving the denitrification efficiency, and at the same time achieving the reduction of discarded oyster shells.

[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 in the treatment of ammonia nitrogen wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A simplified structural schematic diagram of a system for purifying ammonia nitrogen wastewater by using oyster shells to enhance photosynthetic microorganisms provided by the present invention.

[0029] Figure 2 A schematic flow chart of a method for purifying ammonia nitrogen wastewater by using oyster shells to enhance photosynthetic microorganisms provided by the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Rhodopseudomonas palustris CGMCC 1.8929, Rhodospirillum rubrum CGMCC 1.5005, and Rhodopseudomonas faecalis CGMCC1.2176 were purchased from China General Microbiological Culture Collection Center.

[0032] Exothiorhodospirillum sabio ACCC 19809 was purchased from China Agricultural Microbial Culture Collection Center.

[0033] Example 1

[0034] like Figure 1 As shown, a system for purifying ammonia nitrogen wastewater by using oyster shells to enhance photosynthetic microorganisms includes: a wastewater regulating module, a biochemical denitrification module, and an effluent module.

[0035] The wastewater regulation module includes a regulating tank and a dosing room. The regulating tank is divided into two parts: the front section and the back section. The bottom of the front section of the regulating tank is provided with an agitator for regulating the wastewater quality, and the back section of the regulating tank is used to store and regulate the water volume. The dosing room is provided with an acid storage tank, an alkali storage tank and a flocculant storage tank, which are used to store hydrochloric acid solution, sodium hydroxide solution and polyaluminium chloride solution respectively, and each storage tank is connected to the front section of the regulating tank through a pipeline.

[0036] The biochemical denitrification module comprises a microbial culture room, a biochemical reaction pool and a sedimentation pool. The microbial culture room is provided with four bacterial culture tanks and one seed liquid storage tank. The four bacterial culture tanks are connected with the seed liquid storage tank through pipelines. The seed liquid storage tank is connected with the biochemical reaction pool through pipelines. The biochemical reaction pool and the sedimentation pool are interconnected through pipelines. Ammonia nitrogen wastewater can enter the sedimentation pool from the biochemical reaction pool by gravity.

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

[0038] Example 2

[0039] Screening of the compound ratio of photosynthetic microorganisms

[0040] The enriched bacterial liquids of four kinds of photosynthetic bacteria, namely, Rhodopseudomonas palustris CGMCC 1.8929, Rhodospirillum crimsonii CGMCC 1.5005, Exothiorhodospirillum sabii ACCC 19809 and Rhodopseudomonas faecalis CGMCC 1.2176, were compounded in different volume ratios to obtain seed liquid, and the seed liquid was added into the ammonia nitrogen wastewater at an inoculation rate of 10%. After 3 days of photosynthetic purification reaction, the ammonia nitrogen removal rate in the wastewater was measured. The results are shown in Table 1.

[0041] Table 1 Results of photosynthetic microorganism selection and compounding

[0042]

[0043] It can be seen from Table 1 that the seed solution obtained by compounding the bacterial solution of Rhodopseudomonas palustris: Rhodospirillum crimson: Rhodospirillum saburoides: Rhodopseudomonas faecalis in a volume ratio of 5:2:2:1 has the highest removal rate of ammonia nitrogen of 93.80%.

[0044] Example 3

[0045] like Figure 2 As shown, a method for purifying ammonia nitrogen wastewater by enhancing photosynthetic microorganisms with oyster shells comprises the following steps:

[0046] S1. Selection and compounding of photosynthetic microorganisms: Four types of photosynthetic bacteria, including Rhodopseudomonas palustris CGMCC 1.8929, Rhodospirillum crimsonii CGMCC1.5005, Exothiospirillum sabori ACCC 19809, and Rhodopseudomonas faecalis CGMCC 1.2176, were selected to purify ammonia nitrogen wastewater. Each strain was cultured and enriched until the bacterial solution concentration reached 10 8 CFU / mL, the seed solution was prepared by compounding the bacterial solution of Rhodopseudomonas palustris: Rhodospirillum crimson: Rhodospirillum sabii: Rhodopseudomonas faecalis in a volume ratio of 5:2:2:1;

[0047] S2. Adjustment of wastewater quality and quantity: transport the ammonia nitrogen wastewater to the regulating tank, adjust the pH value of the wastewater to between 7.0 and 9.0 using hydrochloric acid solution and sodium hydroxide solution, remove suspended particles in the wastewater using 0.1% polyaluminium chloride solution, obtain homogenized ammonia nitrogen wastewater, store the wastewater in the regulating tank, and transport it to the biochemical reaction tank in an evenly distributed manner;

[0048] S3. Start of cultivation in the biochemical reaction pool: transport the effluent from the regulating pool to the biochemical reaction pool until it reaches the maximum water treatment capacity of the biochemical reaction pool. Close the inlet and outlet pipes of the biochemical reaction pool and transport the seed liquid to the biochemical reaction pool at 0.5% of the maximum water treatment capacity of the biochemical reaction pool. After 15 days of closed cultivation, the ammonia nitrogen concentration in the wastewater is lower than 5 mg / L, and the biochemical reaction pool is successfully started.

[0049] S4. Oyster shells strengthen photosynthetic microorganisms to purify ammonia nitrogen wastewater: After the biochemical reaction tank is successfully started, the oyster shells are hung 20-50 cm below the liquid surface of the biochemical reaction tank, and the inlet and outlet pipes of the biochemical reaction tank are opened to continuously purify the ammonia nitrogen wastewater. The hydraulic retention time of the ammonia nitrogen wastewater in the biochemical reaction tank is controlled to be 48 hours, and fresh seed liquid is added to the biochemical reaction tank every day at 0.05% of the water storage volume of the biochemical reaction tank;

[0050] S5. Sludge sedimentation: The wastewater discharged from the biochemical reaction tank is transported to the sedimentation tank, and the hydraulic retention time in the sedimentation tank is controlled to 4 hours, and the sludge generated during the biochemical reaction is removed by sedimentation;

[0051] S6. Water quality monitoring: The effluent from the sedimentation tank is transported to the outlet tank, and the water quality is automatically monitored by the in-situ water quality detection device to ensure that the wastewater meets the discharge standards. If the water quality in the outlet tank does not meet the standards, the wastewater in the outlet tank needs to be transported to the emergency tank, and after the system is restored to stability, it will be 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 in the protection scope of the present invention.

Claims

1. A method for purifying ammonia nitrogen wastewater by strengthening photosynthetic microorganisms with oyster shells, characterized in that: The steps include: S1. Selection and compounding of photosynthetic microorganisms: Four types of photosynthetic bacteria, Rhodopseudomonas palustris CGMCC 1.8929, Rhodospirillum crimsonii CGMCC1.5005, Exothiospirillum sabori ACCC 19809, and Rhodopseudomonas faecalis CGMCC 1.2176, were selected to purify ammonia nitrogen wastewater, and each strain was cultured and enriched, and then compounded to obtain seed solution; S2. Regulation of wastewater quality and quantity: transport the ammonia nitrogen wastewater to the regulating tank, adjust the pH value of the wastewater to neutral with acid and alkali, remove suspended particles in the wastewater with flocculants, obtain homogenized ammonia nitrogen wastewater, store it in the regulating tank, and transport it to the biochemical reaction tank in an evenly distributed manner; S3, biochemical reaction pool cultivation start: the effluent from the regulating pool is transported to the biochemical reaction pool until the maximum water treatment capacity of the biochemical reaction pool is reached, the inlet and outlet pipes of the biochemical reaction pool are closed, the seed liquid is transported to the biochemical reaction pool, and the closed cultivation is carried out until the water quality meets the standard, which means that the biochemical reaction pool is successfully started; S4. Oyster shells strengthen photosynthetic microorganisms to purify ammonia nitrogen wastewater: After the biochemical reaction tank is successfully started, oyster shells are hung below the liquid surface of the biochemical reaction tank, and the inlet and outlet pipes of the biochemical reaction tank are opened to continuously purify the ammonia nitrogen wastewater. The hydraulic retention time of the 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 sedimentation: The wastewater discharged from the biochemical reaction tank is transported to the sedimentation tank, and the hydraulic retention time in the sedimentation tank is controlled to be 4 h~8 h, and the sludge generated during the biochemical reaction is removed by sedimentation; S6. Water quality monitoring: The effluent from the sedimentation tank is transported to the outlet tank, and the water quality is automatically monitored by the in-situ water quality detection device to ensure that the wastewater meets the discharge standards. If the water quality in the outlet tank does not meet the standards, the wastewater in the outlet tank needs to be transported to the emergency tank, and after the system is restored to stability, it is transported back to the biochemical reaction tank for treatment.

2. The method for purifying ammonia nitrogen wastewater by enhancing photosynthetic microorganisms with oyster shells according to claim 1, characterized in that: Step S1: The concentration of each strain enrichment solution is not less than 10 8 CFU / mL, the volume ratio of the strain enrichment solution is Rhodopseudomonas palustris CGMCC 1.8929:Rhodospirillum rubrum CGMCC 1.5005:Exothiorhodospirillum sabori ACCC 19809:Rhodopseudomonas faecalis CGMCC 1.2176=3~5:1~2:1~2:1~2.

3. The method for purifying ammonia nitrogen wastewater by enhancing photosynthetic microorganisms with oyster shells according to claim 1, characterized in that: In step S2, the acid solution and the alkali solution are hydrochloric acid solution and sodium hydroxide solution respectively, and the flocculant is one or more of polyaluminium chloride, polyaluminium 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 by enhancing photosynthetic microorganisms with oyster shells according to claim 1, characterized in that: When the biochemical reaction pool cultivation is started in step S3, the seed liquid delivery rate is 0.3% to 0.5% of the maximum water treatment volume of the biochemical reaction pool, and the ammonia nitrogen concentration in the wastewater is lower than 5 mg / L, which means that the water quality meets the standard.

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

6. A system for purifying ammonia nitrogen wastewater by enhancing photosynthetic microorganisms with oyster shells, characterized in that: It includes a wastewater regulating module, a biochemical denitrification module and a water outlet module. The wastewater regulating module includes a regulating tank and a dosing room. The regulating tank is divided into a front section and a rear section. A stirrer is provided at the bottom of the front section of the regulating tank for regulating the quality of wastewater. The rear section of the regulating tank is used to store and regulate the amount of water. The dosing room is provided 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 regulating tank through a pipeline. The biochemical denitrification module comprises a microbial culture chamber, a biochemical reaction tank and a sedimentation tank. The microbial culture chamber is provided with 4 bacterial culture tanks and 1 seed liquid storage tank. The 4 bacterial 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 interconnected through pipelines. Ammonia nitrogen wastewater can flow from the biochemical reaction tank into the sedimentation tank by gravity. The water outlet module comprises a water outlet pool and an emergency pool. The water outlet pool is equipped with an in-situ water quality detection device, whose water outlet is connected to the water inlet of the emergency pool through a pipeline, and the water outlet of the emergency pool is connected to the water inlet of the biochemical reaction pool through a pipeline.

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