A method for deep denitrification of sludge by coupling short-cut nitrification-denitrification of chlorella with anaerobic ammonia oxidation in a sequencing batch reactor

Abstract

The present application relates to a kind of in sequence batch reactor using chlorella short-range nitrification denitrification coupling anaerobic ammonia oxidation sludge advanced denitrification method.Microalgae use the carbon dioxide dissolved in water or released by bacterial respiration to produce oxygen for bacteria by photosynthesis under illumination, and bacteria provide metabolites and inorganic carbon source for the growth of microalgae, resulting in most of the ventilation energy saving of algal-bacterial symbiotic system. Short-range nitrification denitrification bacteria and anaerobic ammonia oxidation bacteria achieve efficient removal of nitrogen. Chlorella in microalgae can withstand high ammonia nitrogen, high salt and low temperature, therefore, the process of starting and maintaining dominant algae, short-range nitrification denitrification bacteria and anaerobic ammonia oxidation bacteria community combination has great potential in high ammonia nitrogen wastewater treatment. The present application selects SBR as the reactor, controls pH, DO and records according to preset time, and illuminates the reactor by light incubator, and the removal rates of ammonia nitrogen and total nitrogen reach 99.76% and 98.08% respectively.

Description

TECHNICAL FIELD

[0001] The application relates to a method and device for treating wastewater by using combined biological synergy, and belongs to the technical field of high-concentration ammonia-nitrogen wastewater treatment. BACKGROUND

[0002] With the development of economy, aquaculture wastewater, landfill leachate and other pollutants with high ammonia nitrogen pollute the environment and cause adverse changes in aquatic ecosystems, which have disastrous effects on human health and other organisms in the environment. Carbon emissions caused by energy consumption, chemical use and greenhouse gas production are an important source of carbon emissions in sewage treatment plants. Short-cut nitrification is the conversion of ammonia nitrogen to nitrite under conditions of less dissolved oxygen; under anoxic conditions, nitrite is denitrified to nitrogen, thereby achieving denitrification. Nitrifying bacteria involved in short-cut nitrification are divided into two groups of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), and AOB can oxidize ammonia nitrogen to nitrite. Compared with traditional biological denitrification, short-cut nitrification saves 40% of carbon sources and 25% of aeration. Therefore, short-cut nitrification-denitrification can remove nitrogen efficiently while reducing sludge production and energy consumption.

[0003] Algae fix 50% of the global carbon, making an important contribution to reducing greenhouse gas emissions. Algae can also utilize and fix nitrogen, helping to maintain the nitrogen balance of water bodies. Chlorella, a type of algae, has strong adaptability to extreme environments. The oxygen provided by chlorella can replace the oxygen produced by the aeration system in traditional denitrification processes, and the electrical energy used to produce oxygen by the aerator can be saved. Algae maintain their life activities by absorbing nitrogen, increase their biomass and release oxygen, and can also produce substances that are easy to absorb and degrade. In addition, nitrifying bacteria absorb dissolved oxygen in water to induce ammonia nitrogen in wastewater to become nitrite and nitrate, and denitrifying bacteria convert them into nitrogen.

[0004] However, there is little research on the symbiotic system of short-cut nitrifying bacteria and chlorella for treating high-concentration ammonia-nitrogen wastewater, and the efficient growth and biomass accumulation of the two organisms in a high-ammonia-nitrogen environment to remove nitrogen in water still need to be explored. Although short-cut nitrifying sludge has been domesticated, its nitrification function may decrease if aeration is not provided, and water eutrophication may occur if only algae are relied on for assimilation. Sewage biological treatment technology has been relatively mature so far, and has been widely used in the treatment of high-nitrogen wastewater, but the treatment efficiency can still be improved. Therefore, it is of great significance to develop sewage biological treatment technology and methods with the dual advantages of pollution reduction and carbon reduction for the low-carbon and efficient operation of sewage treatment plants. SUMMARY

[0005] To solve the technical problems existing in the prior art, the application provides a method for deep denitrification of Chlorella short-cut nitrification and denitrification coupled sludge.

[0006] The technical scheme of the application is that the nitration sludge particles of Chlorella domesticated by light growth are used to treat high ammonia-nitrogen wastewater, and a matching wastewater treatment device is designed according to the corresponding technical route, so that the purpose of economically and efficiently removing high-concentration wastewater is achieved.

[0007] The application takes early landfill leachate as a treatment object, and deeply studies the influence and control factors of short-cut nitrification and anaerobic ammonia oxidation for achieving economic and efficient carbon removal, denitrification and desulfurization.

[0008] The application provides an economic and efficient scheme for treating high ammonia-nitrogen low carbon-nitrogen ratio wastewater by using a bacteria-algae symbiotic system.

[0009] The technical scheme of the application is:

[0010] The device for deep denitrification of Chlorella short-cut nitrification and denitrification coupled sludge designed by the application has the following characteristics:

[0011] The device comprises a water inlet tank (I), an illumination incubator (II), an SBR (III) and a water outlet tank (IV) connected in series to form the whole treatment device.

[0012] The water inlet tank is provided with a submersible agitator (1) for stirring the wastewater to be treated to achieve homogeneity.

[0013] The illumination incubator II is provided with an illumination incubator top lamp (5) and an LED lamp tube (28) in the box body, two ventilation openings (8) on the back of the box body, a bearing plate (12) and heat dissipation holes (13) for auxiliary heat dissipation.

[0014] III-SBR: The upper end of the SBR includes a mechanical stirrer (6), an SBR water inlet valve (7), and is made of organic glass and does not contact the external environment. The SBR sidewall has a first drain (9), a second drain (10), and a third drain (11), and a pH and DO monitor (29) contacts the water body through a cover top hole, and the display screen on the device will display the pH and dissolved oxygen values.

[0015] Outlet water tank IV: The outlet water system is composed of a peristaltic pump (30), an outlet pipe (31), and an outlet water tank drain (32). The outlet water tank is used to collect the sewage discharged from the SBR, and samples are taken from here each time. The outlet water tank drain (32) is used to drain the outlet water tank filled with water.

[0016] Before the above steps are performed, preliminary cultivation of the algal granular sludge in the device needs to be completed.

[0017] The steps of the application for treating high ammonia-nitrogen wastewater using a SBR-illumination incubator combination, characterized in that:

[0018] The water inlet water tank is used to simulate high ammonia-nitrogen low carbon-nitrogen ratio wastewater, and the concentration of different components is 191 mg / L NH4Cl, 141 mg / L glucose, 44 mg / L KH2PO4, 5.6 mg / L CaCl2·2H2O, 75 mg / L MgSO4·7H2O, 50 mg / L KHCO3, trace element I 1 mL / L (EDTA 5000 mg / L and FeSO4 5000 mg / L), trace element II 1 mL / L (EDTA 1000 mg / L, H3BO4 14 mg / L, MnCl2·4H2O 990 mg / L, CuSO 4· 5H2O 250 mg / L, ZnSO4·7H2O 430 mg / L, NiCl2·6H2O 190 mg / L, NaMoO4·2H2O 220 mg / L). The pH of the inlet water is controlled between 8.0 and 8.5. Stirring and mixing are performed by a submersible mixer (1) to achieve homogeneity. The inlet water tank I outlet valve (2) and the SBR water inlet valve (7) are opened, and the raw water is injected into the SBR reactor containing the bacteria-algae symbiotic activated sludge by the peristaltic pump (4). The bacteria-algae granular sludge accounts for 15%-20% of the effective volume of the reactor, and the initial mixed liquor suspended solids (MLSS) concentration is 5200±50 mg / L.

[0019] III-SBR: The upper end of the SBR includes a mechanical stirrer (6), an SBR water inlet valve (7), and is made of organic glass and does not contact the external environment. The SBR sidewall has a first drain (9), a second drain (10), and a third drain (11), and a pH and DO monitor (29) contacts the water body through a cover top hole, and the display screen on the device will display the pH and dissolved oxygen values.

[0020] Before starting the SBR mechanical stirring device, the light incubator II needs to be set. The incubator has both the two side LED lamps (28) and the top lamp (5) of the box; turn on the liquid crystal display (14) and set the light incubator control program; click the setting button (23), set the light intensity value (17) to 1, which is 3000 lux, by pressing the up (25) and down (26) buttons, turn on the light by clicking the light on-off button (21), and the top lamp (5) and the two side LED lamps (28) of the incubator are lit. Click the mode switching button (24) to switch the time setting to the temperature setting interface, and set the temperature setting value (19) to 25 degrees. The air vent (8) is used to exhaust the gas generated by the SBR and the excess heat generated, and the heat dissipation hole (13) assists in heat dissipation, so that the temperature of the box is maintained at 25 degrees. After setting the temperature and light intensity, click the incubator reaction start-stop button (27) to restart, and the light incubator starts to operate. Place the SBR reactor on the receiving plate (12), turn on the SBR mechanical stirrer (6), and start the first cycle of the SBR operation.

[0021] After the last process of each cycle is completed, open the SBR second drain (10) and start the water outlet bucket water inlet pump (30) to pump the supernatant into the water outlet bucket IV through the SBR water outlet pipe (31). After each cycle is completed, sample is taken at this point, and then the water quality indicators are analyzed and monitored.

[0022] The cultivation and inoculation of the bacterial-algal granular sludge in the SBR include the following steps:

[0023] Mix the chlorella collected from the freshwater lake with the activated sludge taken from the secondary sedimentation tank of the AO tank of the sewage plant, and cultivate them in a conical flask in the laboratory with 50-200 mg / L of high ammonia nitrogen concentration sewage containing ammonium chloride, so as to realize the mixing of algae with sedimentation capacity and ordinary activated sludge. Place the above-mentioned in a shaking table to cultivate for two weeks at 60-80 rpm, wash away the suspended bacterial-algal granules that are not combined with the activated sludge for 5-7 times, each time for 30-50 minutes, until the supernatant and the sludge layer have a clear interface. If the supernatant is still turbid after completing the whole washing process, it should be repeated once.

[0024] The short-cut nitrification-denitrification and anaerobic ammonia oxidation activated sludge used for combined cultivation has been used to treat low carbon-nitrogen ratio (2.5:1-3:1) leachate for 30 days, so as to enrich short-cut nitrifying bacteria, denitrifying bacteria and anaerobic ammonia oxidation bacteria, and the sludge concentration is 4000±50 mg / L.

[0025] Compared with the prior art, the present application has the following technical effects:

[0026] The present technology realizes the removal of total nitrogen without aeration and the efficient removal of ammonia nitrogen by jointly decomposing inorganic nutrients in low-carbon-nitrogen-ratio high-ammonia-nitrogen wastewater by algae and bacteria, and the removal rates of ammonia nitrogen and total nitrogen can reach 99.76% and 98.08%, respectively.

[0027] Microalgae can absorb nitrogen in wastewater to convert it into biomass and release O2 and organic matter through photosynthesis to meet the growth needs of most aerobic bacteria. Bacteria mineralize the organic matter produced by algae and the organic matter in wastewater through respiration to produce CO2 as raw materials for photosynthesis. Algae consume nitrogen through assimilation to help maintain nitrogen fixation. The dissolved oxygen in the reactor is controlled at 0.4 mg / L-0.5 mg / L, and the pH is controlled in the range of 7.5-8.5, and nitrifying bacteria convert ammonia nitrogen into nitrite and nitrate. Then denitrifying bacteria play a role in denitrifying nitrite and nitrate into nitrogen to remove ammonia nitrogen in water.

[0028] The bacteria-algae symbiotic system realizes an internal ecological balance through these mechanisms, effectively utilizes and recycles nutrients, reduces external nutrient input, and reduces the risk of eutrophication.

[0029] After the first operating cycle of the SBR, the bacteria-algae granular sludge is in a state of requiring nutrients, and the unit weight of the symbiotic sludge has a large adsorption surface area. When the influent enters the next operating period, the activated sludge can fully exert the initial adsorption removal effect, and then complete the treatment of low-carbon-nitrogen-ratio high-ammonia-nitrogen-concentration wastewater by the sequencing batch bacteria-algae symbiotic system.

[0030] Before starting the SBR mechanical stirrer, set up the light incubator II; the incubator has both the two side LED lamps (28) and the top lamp (5) of the box; turn on the liquid crystal display (14) and set the light incubator control program; click the setting button (23), set the light intensity value (17) to 1, which is 3000 lux, by pressing the up (25) and down (26) buttons, turn on the light by clicking the light on-off button (21), the light incubator top lamp (5) and the box wall two side LED lamp (28) are lit; click the mode switching button (24) to switch the time setting to the temperature setting interface, set the temperature setting value (19) to 25℃; the air vent (8) is used to exhaust the gas generated by the SBR and the excess heat generated, and the heat dissipation hole (13) assists in heat dissipation, so that the box temperature is maintained at 25℃; after setting the temperature and light intensity, click the incubator reaction start-stop button (27) to restart, so that the light incubator starts to operate; place the SBR reactor on the receiving plate (12), start the SBR mechanical stirrer (6), and start the first cycle of SBR operation;

[0031] After the last process of each cycle, the second SBR drain (10) is opened, the water inlet pump (30) is started, the supernatant is pumped into the water outlet bucket IV through the SBR water outlet pipe (31), and sampling is taken at the end of each cycle, and then the water quality indicators are analyzed and monitored;

[0032] The SBR is periodically operated in the mode of "inlet-reaction-sedimentation-drainage".

[0033] The cultivation and inoculation of the bacteria-algae symbiotic activated sludge comprises the following steps:

[0034] The algae are Chlorella, and the cell number is 9.39×10 9 ~ 1.01×10 10 cells / L;

[0035] The short-cut nitrification-denitrification and anaerobic ammonia oxidation active sludge for combined cultivation has been used to treat leachate with a carbon-nitrogen ratio of 2.5:1-3:1 for 30 days, so as to enrich short-cut nitrifying bacteria, denitrifying bacteria and anaerobic ammonia oxidation bacteria, and the sludge concentration is 4000±50 mg / L;

[0036] The Chlorella and the activated sludge are put into a conical flask, the Chlorella and the short-cut nitrification-denitrification and anaerobic ammonia oxidation active sludge are fully mixed, and then 50-200 mg / L of high-ammonia-nitrogen-concentration sewage is injected into the conical flask; the volume ratio of Chlorella to activated sludge is 1:1; the above-mentioned conical flask is placed in a shaking bed for cultivation for two weeks at 60-80 rpm, and the suspended bacteria-algae particles that are not combined with the activated sludge are washed away for 5-7 times, each time for 30-50 minutes, until there are no suspended bacteria-algae particles in the supernatant;

[0037] During the process of pouring out the supernatant, it should be ensured that the bacteria-algae particles are not lost with the water flow;

[0038] The pH and DO of the SBR reactor are monitored every 3 hours;

[0039] When the incubator light is on, the light intensity is 3000 lux; the reactor is uniformly illuminated from both sides and the top; and the dissolved oxygen is controlled to be 0.4-0.5 mg / L;

[0040] During the short-cut nitrification-denitrification operation stage, the pH is 7.3-8.5; when the pH is greater than 8.5, hydrochloric acid is added to reduce the pH to below 8.5, and when the pH is less than 7.3, sodium bicarbonate is added to restore the pH to 7.3-8.5;

[0041] The physiological activity of chlorella is controlled by changing the light intensity and time to control the dissolved oxygen in the reactor; when the dissolved oxygen is lower than 0.5 mg / L, the light intensity is increased to 2 grades through the liquid crystal display screen of the light incubator, and the light intensity is 4500 lux, so that the metabolic activity of algae is increased, and the concentration of dissolved oxygen in the reactor is increased.

[0042] Technical principle

[0043] Using the bacteria-algae symbiotic system to remove nitrogen elements in wastewater has cost-effectiveness and sustainability, and is a promising technology. The present application uses chlorella short-range nitrification and denitrification coupled with anaerobic ammonia oxidation sludge to treat high-ammonia-nitrogen simulated low-carbon-nitrogen-ratio wastewater. By controlling the dissolved oxygen, the nitrite nitrogen is prevented from being converted into nitrate nitrogen, and the denitrification reaction directly uses nitrite nitrogen as the electron acceptor to convert the nitrite nitrogen into nitrogen gas, thereby achieving nitrogen removal. At the same time, the unconverted ammonia nitrogen and nitrite nitrogen also undergo anaerobic ammonia oxidation reaction to further remove nitrogen from the system. The algae in the bacteria-algae granules can also further improve the denitrification efficiency of the system through assimilation. The concentration of nitrite nitrogen inhibits the growth of algae, and light can reduce the resistance of algal growth by inhibiting nitrite, and can also promote NO3 - -N and NO2 - -N denitrification.

[0044] In the traditional SBR operation process, aeration is first carried out to achieve partial short-range nitrification to accumulate nitrite nitrogen by controlling the dissolved oxygen and free ammonia. In the process, the horizontal aerobic ammonia-oxidizing bacteria mainly include Nitrosomonas, Nitrosococcus, and Nitrosospira, and the former plays a major role in the denitrification treatment of wastewater. The ammonia-oxidizing bacteria oxidize ammonia nitrogen to nitrite by a series of enzymes and intermediates, achieving the conversion of ammonia nitrogen. The traditional denitrification process refers to the horizontal denitrifying bacteria mainly including Thiobacillus and Bacillus, which convert nitrate nitrogen to nitrogen gas under anoxic conditions using sodium acetate as the carbon source, while short-range denitrification uses less carbon source to convert nitrite nitrogen to nitrogen gas. Anaerobic ammonia oxidation is an autotrophic denitrification technology, and under the action of anaerobic ammonia oxidation bacteria, ammonia nitrogen and nitrite nitrogen undergo anaerobic ammonia oxidation reaction to produce nitrogen gas and nitrate, and the process does not consume oxygen and carbon source.

[0045] Chlorella can produce oxygen and degradable organic matter by absorbing carbon dioxide through photosynthesis, not only providing oxygen for ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), but also promoting the growth of its own biomass. The order of nitrogen salt removal by chlorella is generally NH4 + -N>NO3 - -N>NO2 -The interaction between N. sphaeroides and short-cut nitrification-denitrification ANAMMOX may aggravate the assimilation of ammonium. It can be seen that the two are interrelated and restricted in the bacterio-algal symbiotic system.

[0046] Compared with the prior art, the process designed in the application has the following advantages:

[0047] (1) The optimum temperature of nitrifying bacteria is likely to be 25-45 DEG C, while Chlorella sphaeroides grows faster in an environment of 25-35 DEG C. The temperature of the incubator is 25 DEG C and does not change with the change of external temperature, so that the normal metabolic activities of the algae and bacteria are ensured. Chlorella sphaeroides can provide dissolved oxygen to nitrifying bacteria through its own physiological activities to help replace the aerator, and can also use the carbon dioxide produced by the bacteria to maintain its own metabolic activities, thereby reducing carbon emissions.

[0048] (2) The SBR process is used as the main process for nitrogen removal, and the SBR process is fully utilized due to its simple process, cost saving, simple operation and flexible operation mode. The ideal plug flow process has large biochemical reaction driving force and high efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 The figure is a system nitrogen element concentration change graph.

[0050] Figure 2 The figure is a schematic diagram of a device for realizing deep denitrification of sludge by using Chlorella sphaeroides coupled with nitrification and denitrification.

[0051] The device comprises a water inlet tank (I), an illumination incubator (II), an SBR (III) and a water outlet tank (IV) connected in series to form the entire treatment device.

[0052] The water inlet tank: 1-submersible agitator, 2-water inlet regulating valve, 3-water outlet pipe, 4-SBR water inlet pump.

[0053] The illumination incubator II: 5-top light of the illumination incubator, 8-vent, 9-first SBR drain port, 10-second SBR drain port, 11-third SBR drain port, 12-accepting plate, 13-heat dissipation hole, 14-liquid crystal display, 15-temperature measurement value, 16-humidity measurement value, 17-light intensity value, 18-single cycle setting time, 19-temperature setting value, 20-humidity setting value, 21-lamp on / off button, 22-lock, 23-set, 24-mode switching, 25-setting value down button, 26-setting value up button, 27-reaction on / off button, 28-LED lamp.

[0054] III-SBR: 6-SBR mechanical agitator, 7-SBR water inlet valve, 9-first SBR drain port, 10-second SBR drain port, 11-third SBR drain port, 29-pH and DO monitor

[0055] Water tank IV: 30 - third drain, 31 - water outlet pipe, 32 - water tank drain. DETAILED DESCRIPTION

[0056] The test water was synthetic wastewater with high ammonia nitrogen and low carbon to nitrogen ratio, and the initial mixed liquor suspended solids (MLSS) concentration was 5200 ± 50 mg / L. The wastewater in the influent tank was composed of aqueous solutions with concentrations of 191 mg / L NH4CI, 141 mg / L glucose, 44 mg / L KH2PO4, 5.6 mg / L CaCI2-2H2O, 75 mg / L MgSO4-7H2O, 50 mg / L KHCO3, trace element I 1 mL / L (EDTA 5000 mg / L and FeSO4 5000 mg / L), trace element II 1 mL / L (EDTA 1000 mg / L, H3BO4 14 mg / L, MnCI2-4H2O 990 mg / L, CuSO4-5H2O 250 mg / L, ZnSO4-7H2O 430 mg / L, NiCI2-6H2O 190 mg / L, NaMoO4-2H2O 220 mg / L). The influent pH was controlled between 8.0 and 8.5. 4·

[0057] In order to obtain well-mixed granular algal-bacterial sludge, Chlorella vulgaris and activated sludge rich in short-cut nitrification-denitrification bacteria were cultured and inoculated. Chlorella vulgaris collected from a freshwater lake was mixed with activated sludge taken from the secondary sedimentation tank after the AO tank of a wastewater treatment plant, and the cell number of Chlorella vulgaris was 9.39 x 10 9 ~ 1.01 x 10 10 cells / L, and the activated sludge concentration taken from the secondary sedimentation tank after the AO tank of a wastewater treatment plant was 4000 ± 50 mg / L, and the Chlorella vulgaris and activated sludge were cultured in a conical flask in the laboratory with 50-200 mg / L of ammonium chloride high-ammonia-nitrogen-concentration wastewater, and the volume ratio of Chlorella vulgaris to activated sludge was 1:1. After the above-mentioned conical flask was placed in a shaker for two weeks at 60-80 rpm, the suspended algal-bacterial granules that were not combined with the activated sludge were washed away 5-7 times, each time for 30-50 minutes, until the supernatant no longer had suspended algal-bacterial granules.

[0058] The conventional water quality indicators were determined by the national standard method.

[0059] Stirring and mixing were performed by a submersible mixer (1) to achieve homogeneity. The influent tank outlet valve (2) and the SBR influent valve (7) were opened, and the influent tank outlet water passed through the peristaltic pump (4) and entered the SBR, thereby completing the SBR influent.

[0060] ​After the end of the SBR water inlet, the pH and dissolved oxygen (DO) monitoring instrument (29) is set to monitor the pH and DO in real time, so as to determine the reaction state. One cycle of the SBR includes water inlet for 10 minutes, stirring for 720 minutes, sedimentation for 30 minutes, water discharge for 10 minutes, and the operation cycle time is about 1 day. The water discharge ratio, that is, the ratio of the water discharge amount in a single cycle to the total water amount of the reactor, is 10%-30%, and the stirrer speed is controlled at 60-80 rpm per minute.

[0061] The start-up light incubator II is started, and the microalgae-bacteria symbiotic granules are alternately and intermittently contacted with light energy. The incubator has two side LED lamps (28) and a top lamp (5); the liquid crystal display (14) is turned on, the light incubator control program is set, the light intensity value (17) is set to 1, that is, 3000 lux by pressing the up (25) and down (26) buttons, the light is turned on by pressing the light on-off button (21), the top lamp (5) and the two side LED lamps (28) of the incubator are turned on, the mode switching button (24) is pressed, the temperature setting interface is switched, the temperature setting value (19) is set to 25°C, the ventilation port (8) is used to discharge the gas generated by the SBR and the excess heat, and the heat dissipation hole (13) is used to assist heat dissipation, so that the temperature of the incubator is maintained at 25°C. After the temperature and light intensity are set, the incubator reaction start-stop button (27) is pressed to restart, and the light incubator starts to operate. The SBR reactor is placed on the receiving plate (12), the SBR mechanical stirrer (6) is started, and the first cycle of the SBR operation is started.

[0062] After the end of the last process of each cycle, the SBR second water outlet (10) is opened, the water inlet pump (30) of the water outlet bucket is started, the supernatant is pumped into the water outlet bucket IV through the SBR water outlet pipe (31), and the supernatant is sampled at the end of each cycle, and then the ammonia nitrogen and total nitrogen concentrations in the supernatant are analyzed and monitored.

[0063] The creativity of the present application is as follows:

[0064] 1. The Chlorella sp. collected from a freshwater lake is mixed with the activated sludge taken from the secondary sedimentation tank of the AO tank of a sewage treatment plant, and is cultured in a conical flask containing 50-200 mg / L of high-ammonia-nitrogen-concentration sewage in the laboratory, so as to realize the mixing of the algae with sedimentation capacity and the ordinary activated sludge. The above is placed in a shaking bed for culture for two weeks at 60-80 rpm, and the suspended bacteria-algae granules that are not combined with the activated sludge are washed away for 5-7 times, each time for 30-50 minutes, until the supernatant and the sludge layer have a clear interface. If the supernatant is still turbid after the completion of the whole washing process, the process should be repeated once.

[0065] The combined cultivation of short-cut nitrification and denitrification and anaerobic ammonia oxidation sludge for half a month has been used for treating low carbon-nitrogen ratio (2.5:1-3:1) leachate, and short-cut nitrification bacteria and denitrification bacteria are enriched for 30 days.

[0066] 2. Real-time monitoring of pH and DO by online pH and dissolved oxygen (DO) monitoring equipment of SBR to determine the reaction state, detection once every 3 hours; sampling once every 24 hours, and analyzing and monitoring the water quality indicators. Continuously illuminate the reactor, and the SBR adopts the cycle operation mode of "influent-reaction-settlement-drainage", and the influent and settlement time of each operation cycle is 10 minutes and 30 minutes respectively, and the stirring time is 720 minutes.

[0067] 3. The metabolic activity of algae is controlled by setting the illumination time and illumination intensity in the illumination incubator, and the temperature setting in the illumination incubator is safer than heating the SBR by heating rods.

[0068] 4. Under low aeration conditions, microalgae and activated sludge are used to remove organic matter and nutrients in wastewater, and the sludge and biofilm are fully mixed for material exchange in the stirring stage, and in this process, algae can fully contact light energy to realize the growth of algae. The removal rates of ammonia nitrogen and total nitrogen can reach 99.76% and 98.08% respectively, realizing high-efficiency degradation of pollutants in water without aeration, and reducing the energy consumption of wastewater treatment.

[0069] 5. The core process of the present application is to carry out short-cut nitrification and denitrification of Chlorella pyrenoidosa coupled with anaerobic ammonia oxidation sludge in a sequencing batch reactor for deep denitrification.

[0070] 6. The nitrification reaction is controlled in the short-cut nitrification stage, avoiding excessive consumption of dissolved oxygen, and nitrite is also denitrified to nitrogen. The bacteria-algae symbiotic system improves the denitrification reaction rate of the reactor. The present application provides guidance for the cooperative treatment of wastewater by bacteria and algae, and provides guidance for the use of a brand-new high-efficiency energy-saving biological method for treating low carbon-nitrogen ratio high ammonia-nitrogen wastewater.

Claims

1. A method for deep nitrogen removal from sludge using Chlorella short-cut nitrification-denitrification coupled with anaerobic ammonium oxidation in a sequencing batch reactor, characterized in that: The influent to the influent tank is simulated high ammonia nitrogen and low carbon-to-nitrogen ratio wastewater. The influent contains 191 mg / L NH4Cl, 141 mg / L glucose, 44 mg / L KH2PO4, 5.6 mg / L CaCl2·2H2O, 75 mg / L MgSO4·7H2O, 50 mg / L KHCO3, 1 mL / L of trace element I, and 1 mL / L of trace element II. Trace element I contains 5000 mg / L EDTA and 5000 mg / L FeSO4; trace element II contains 1000 mg / L EDTA, 14 mg / L H3BO4, 990 mg / L MnCl2·4H2O, 250 mg / L CuSO4·5H2O, and ZnSO4. 4· 7H2O 430mg / L, NiCl2·6H2O 190mg / L and NaMoO4·2H2O 220mg / L; the pH of the influent is controlled between 8.0 and 8.5; the influent is stirred and mixed by a submersible mixer (1) to achieve homogeneity; the outlet valve (2) of the influent tank I and the SBR influent valve (7) are opened, and the raw water is injected into the SBR reactor containing symbiotic sludge of bacteria and algae through a peristaltic pump (4). The sludge particles of bacteria and algae account for 15%-20% of the effective volume of the reactor, and the initial mixed liquor suspended solids (MLSS) concentration is 5200±50mg / L; After the III-SBR influent is completed, the pH and DO are monitored in real time by the online pH and dissolved oxygen (DO) monitor (29) of the SBR; one cycle of the SBR includes 10 minutes of influent, 720 minutes of stirring, 30 minutes of sedimentation, and 10 minutes of drainage, with a cycle time of 12 hours; the drainage ratio, i.e. the ratio of single-cycle drainage to the total water volume of the reactor, is 30%-40%, and the agitator speed is controlled at 60-80 rpm; Before turning on the SBR mechanical stirring device, the light incubator II is set up. The incubator has LED lights (28) on both sides and a light (5) on the top of the chamber. Turn on the LCD screen (14) and set the control program of the light incubator. Click the setting button (23), and by pressing the up (25) and down (26) buttons, set the light intensity value (17) to level 1, which is 3000 lux. Click the light on / off button (21) to turn on the light. The top light (5) of the light incubator and the LED tubes (28) on both sides of the chamber wall are lit up. Click the mode button. Use the mode switch button (24) to switch the time setting to the temperature setting interface and set the temperature setting value (19) to 25℃; the vent (8) is used to exhaust the gas generated by SBR and the excess heat generated, and the heat dissipation hole (13) assists in heat dissipation to keep the temperature of the chamber at 25℃; after completing the temperature and light intensity settings, click the incubator reaction start / stop button (27) to restart and start the light incubator; place the SBR reactor on the support plate (12), turn on the SBR mechanical stirrer (6), and start the first cycle of SBR operation; After the sedimentation of the last process in each cycle, the second drain outlet of the SBR (10) is opened, the water inlet pump of the middle outlet tank (30) is started, and the supernatant is pumped into the outlet tank IV through the SBR outlet pipe (31). Samples are taken here after each cycle, and the water quality indicators are analyzed and monitored. SBR operates cyclically according to the "influent-reaction-sedimentation-discharge" mode.

2. The method for deep nitrogen removal using Chlorella coupled with nitrification-denitrification sludge in a sequencing batch reactor according to claim 1, characterized in that, The cultivation and inoculation of the symbiotic bacteria-algae sludge includes the following steps: The algae is Chlorella vulgaris, with a cell count of 9.39 × 10⁻⁶. 9 ~1.01×10 10 cell / L; The short-cut nitrification-denitrification and anaerobic ammonia oxidation activated sludge used for co-culture has been used to treat leachate with a carbon-to-nitrogen ratio of 2.5:1-3:1 for 30 days, in order to enrich short-cut nitrifying bacteria, denitrifying bacteria and anaerobic ammonia oxidation bacteria, with a sludge concentration of 4000±50 mg / L. Place Chlorella and activated sludge into a conical flask to thoroughly mix the Chlorella with the activated sludge undergoing short-cut nitrification, denitrification, and anaerobic ammonia oxidation. Then, inject wastewater with a high ammonia nitrogen concentration of 50-200 mg / L into the conical flask. The volume ratio of Chlorella to activated sludge is 1:

1. Place the conical flask in a shaker and incubate at 60-80 rpm for two weeks. Wash away any suspended algae and bacteria particles that are not bound to the activated sludge 5-7 times, with each settling time lasting 30-50 minutes, until the supernatant no longer contains any suspended algae and bacteria particles. During the pouring of the supernatant, ensure that the bacterial and algal particles are not lost with the water flow; pH and DO were monitored in the SBR reactor every 3 hours. When the incubator lights are turned on, the light intensity is 3000 lux; the reactor receives uniform illumination from both sides and the top; the dissolved oxygen is controlled at 0.4-0.5 mg / L. During the short-cut nitrification-denitrification operation phase, the pH is 7.3-8.5; when the pH > 8.5, hydrochloric acid is added to lower the pH to below 8.5; when the pH < 7.3, sodium bicarbonate is added to restore the pH to 7.3-8.

5. Dissolved oxygen in the reactor is controlled by adjusting the physiological activities of Chlorella by changing the light intensity and time. When the dissolved oxygen level is below 0.5 mg / L, the light intensity is increased to level 2 (4500 lux) via the LCD screen of the light incubator to increase the metabolic activity of the algae and improve the dissolved oxygen concentration in the reactor.

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