Rapid start-up method for treating anaerobic digestion liquid of piggery wastewater with high ammonia nitrogen and low carbon-nitrogen ratio by algae-bacteria granular sludge system

Abstract

The present invention belongs to the field of wastewater treatment technology, and specifically relates to a rapid start-up method for treating anaerobic digestion liquid of piggery wastewater with high ammonia nitrogen and low carbon nitrogen ratio by using an algae-bacteria granular sludge system. The method is to first inoculate the algae-bacteria granular sludge into the SBR reactor of the algae-bacteria granular sludge, and then control the key influent parameter NH4 + -N / TP constant management strategy to control influent COD and NH4 + ‑N concentration ratio is 3, NH4 + The ratio of ‑N to TP concentration is 10, and the concentration of influent COD and influent NH4 + The performance of the algae-bacteria granular sludge was enhanced by adjusting the -N concentration and influent TP concentration, and the acclimation was carried out in the implementation stage through the actual anaerobic digestion liquid of piggery wastewater, and finally the ammonia nitrogen concentration in the effluent of the algae-bacteria granular sludge after treating the undiluted actual anaerobic liquid of piggery wastewater reached the discharge standard, and the start-up of the algae-bacteria granular sludge was achieved. This method can be used for the start-up of the sequencing batch algae-bacteria granular sludge reactor that acclimates and treats the anaerobic digestion liquid of piggery wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a rapid start-up method for treating anaerobic digestion liquid of piggery wastewater with high ammonia nitrogen and low carbon-nitrogen ratio by using an algae-bacteria granular sludge system. Background Art

[0002] Pig farming has been a traditional agricultural industry for nearly a hundred years, and it has brought significant economic benefits. However, pig farms produce a lot of high-concentration wastewater and feces. If these wastewaters are discharged directly without proper treatment, they will cause serious environmental pollution. Currently, pig farm wastewater is first treated anaerobically before being discharged. Although this can significantly reduce the chemical oxygen demand (COD) in the water, it will also produce a large amount of high-concentration ammonia nitrogen (NH4 + -N) and low carbon and nitrogen (C / N) anaerobic digestate of piggery wastewater.

[0003] Currently, the commonly used methods for treating anaerobic digestate from piggery wastewater include returning to the field, natural ecological treatment, physical and chemical methods, and biological methods. The most commonly used method is the traditional nitrification and denitrification biological method, which is relatively mature, but also has many problems, mainly including the inability to completely remove ammonia nitrogen, large aeration volumes, high carbon dioxide emissions, large amounts of added carbon sources, large amounts of residual sludge, and high treatment costs. Therefore, the development of a piggery wastewater anaerobic digestate treatment system with a simple structure, easy operation, energy conservation and environmental protection, high pollutant removal efficiency, and low treatment costs has broad market prospects.

[0004] The emerging biotechnology algae-bacteria granular sludge not only has the advantages of dense structure, high biomass, good sedimentation capacity and excellent nutrient removal capacity, but also can reduce the energy consumption of external aeration by the synergistic effect of algae and bacteria, thus contributing to the sustainable development of the environment. It provides a new energy-saving, low-carbon and environmentally friendly approach for the treatment of anaerobic digestion liquid of piggery wastewater. However, NH4 + -N and total phosphorus (TP) concentrations are high. Directly using the anaerobic digestate of pig wastewater to domesticate algae-bacteria granular sludge may cause algae to be inhibited by high concentrations of ammonia nitrogen or the high TP concentration may destroy the balance of the microbial community structure, resulting in deterioration of all aspects of the performance of the algae-bacteria granular sludge. Therefore, it is of great significance to determine a feasible influent TP management strategy and scientifically domesticate algae-bacteria granular sludge for treating anaerobic digestate of pig wastewater. Summary of the Invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a method for treating room temperature, high concentration NH4 + The method for starting algae-bacteria granular sludge of anaerobic digestion liquid of piggery wastewater with -N and low C / N ratio is first inoculated with algae-bacteria granular sludge cultured with artificially synthesized urban domestic sewage in the SBR reactor, and then by controlling the key influent parameter NH4 +-N / TP unchanged management strategy, changing the matrix to enhance its treatment performance, and ultimately achieving its start-up in treating anaerobic digestate of swine wastewater.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The present invention provides a method for quickly starting an algae-bacteria granular sludge system for treating anaerobic digestion liquid of piggery wastewater with high ammonia nitrogen and low carbon-nitrogen ratio, the method comprising the following steps:

[0008] S1, the stage of changing substrate to acclimate algae-bacteria granular sludge: inoculate algae-bacteria granular sludge into SBR reactor, then introduce artificial synthetic wastewater containing carbon source, nitrogen source and phosphorus source to acclimate the sludge, and control the influent NH4 + -N / TP constant management strategy to control influent COD / NH4 + -N=3,NH4 + -N / TP=10, influent pH is 7-8, then continuously increase influent COD concentration, influent NH4 + -N concentration and influent TP concentration to enhance the performance of algae-bacteria granular sludge; in each gradient acclimation stage, when the effluent NH4 + -N removal rate must reach more than 95% to enter the next gradient acclimatization, when the influent COD concentration is 1500mg / L, the influent NH4 + When the -N concentration is 500mg / L and the inlet TP concentration is 50mg / L, the outlet NH4 + The -N removal rate has stably reached over 95%, indicating that the stage of substrate transformation and acclimation of algae-bacteria granular sludge has been successful, and the actual anaerobic digestion liquid treatment of piggery wastewater has entered the stage;

[0009] S2. Actual piggery wastewater anaerobic digestion liquid treatment start-up stage: The effluent from the actual piggery wastewater anaerobic digestion tank is used as the inlet water quality of the SBR reactor for the implementation stage of acclimatization, NH4 + -N concentration is 480-560mg / L, COD concentration is 1300-1500mg / L, TP concentration is 20-30mg / L, pH is 7-8, and the reactor water inlet adopts a step water strategy: the actual pig wastewater anaerobic digestion liquid is first diluted twice and run for a period of time, then diluted 4 / 3 times and run for a period of time, and finally run for a period of time without dilution; in each step water strategy, when the effluent NH4 + -N removal rate is stable above 95%, then the next water inlet strategy can be entered; when the reactor inlet water is the actual anaerobic digestion liquid of undiluted pig wastewater, and the effluent NH4 + When the -N removal rate is stable at above 95%, it is considered that the algae-bacteria granular sludge for treating anaerobic digestion liquid of piggery wastewater is successfully started.

[0010] Preferably, the SBR reactor is made of plexiglass, and a water inlet and a water inlet valve are provided at the bottom of the reactor side wall, and the water inlet is connected to the water inlet bucket through a water inlet peristaltic pump, and a water outlet and a water outlet valve are provided in the middle of the reactor side wall, and the water outlet is connected to the water outlet bucket through a water outlet peristaltic pump, and a sampling port and a sampling valve are provided at the upper position of the reactor side wall, and oxygen-enriched sand and gravel are provided on the bottom wall of the reactor, and the oxygen-enriched sand and gravel are connected to an external aeration pump, and a rotor flowmeter is provided between the oxygen-enriched sand and gravel and the aeration pump, and an LED lamp is provided 20 cm away from the outer wall of the reactor.

[0011] More preferably, the LED lamp tube, water inlet peristaltic pump, water outlet peristaltic pump, and aeration pump are connected to a timer to set the operation time, an inlet pipe is connected between the water inlet and the water inlet bucket, a water outlet pipe is connected between the water outlet and the water outlet bucket, and an aeration pipe is connected between the aeration pump and the oxygen-enriched sand and gravel. During the operation of the reactor, the water inlet valve and the water outlet valve are in the open state, and the sampling valve is in the closed state.

[0012] Preferably, the acclimation period of S1 includes five stages, namely stage I, stage II, stage III, stage IV, and stage V. Stage I is from the 1st day to the 20th day, stage II is from the 21st day to the 50th day, stage III is from the 51st day to the 80th day, stage IV is from the 81st day to the 110th day, and stage V is from the 111th day to the 154th day. The influent COD concentration and influent NH4 + -N concentration and influent TP concentration to enhance the performance of algae-bacteria granular sludge, where the COD concentration gradient is 300, 600, 900, 1200, 1500 mg / L, NH4 + The -N concentration gradient was 100, 200, 300, 400, and 500 mg / L, and the TP concentration gradient was 10, 20, 30, 40, and 50 mg / L.

[0013] Preferably, the treatment stage of S2 is composed of three stages. Stage I is the operation stage in which the actual anaerobic digestate of pig wastewater is diluted twice, which runs for a total of 14 days. Stage II is the operation stage in which the actual anaerobic digestate of pig wastewater is diluted 4 / 3 times, which runs for a total of 20 days. Stage III is the operation stage in which the actual anaerobic digestate of pig wastewater is not diluted, which runs for a total of 52 days.

[0014] The whole process of starting the algae-bacteria granular sludge of the present invention includes comparing two different influent TP management strategies to determine a feasible variable substrate acclimation algae-bacteria granular sludge method (154 days of experimental group 1 and 114 days of experimental group 2) and 86 days of actual pig wastewater anaerobic digestion liquid treatment (selecting the experimental group 1 reactor), and finally the ammonia nitrogen concentration in the effluent after the algae-bacteria granular sludge treats the undiluted actual pig wastewater anaerobic liquid to meet the discharge standard, and the removal efficiency of COD, TN and TP is as high as 95.65%-99.14%, 66.57%-81.75%, and 78.04%-87.88% respectively, indicating that the algae-bacteria granular sludge of the present invention for treating pig wastewater anaerobic digestion liquid is successfully started; therefore, NH4 + -N / TP is the key factor for the successful start-up of algae-bacteria granular sludge system;

[0015] Preferably, in S1, a sludge-water mixture of algae-bacteria granular sludge cultured with artificially synthesized municipal sewage with an initial sludge concentration of 4 g MLSS / L is inoculated into the SBR reactor.

[0016] Preferably, during S1 and S2, the reactor is operated intermittently, maintaining a lighting condition of 12 hours of light / 12 hours of darkness every day, and the LED tube provides 3000-4000 lux of light. The operating cycle of the reactor is 8 hours, including five stages: water inlet, anaerobic reaction, aerobic reaction, sedimentation and drainage. Among them, the water inlet flow rate is 80 mL / min, the water inlet time is 5 minutes, the anaerobic reaction is not aerated, the anaerobic reaction time is 235 minutes, the aerobic reaction is aerated, and the aeration flow rate is controlled to be 3.5-4 L / min, the aerobic reaction time is 235 minutes, the sedimentation time is 2 minutes, the water exchange ratio in the drainage stage is 50%, and the drainage time is 3 minutes.

[0017] Preferably, during S1 and S2, the temperature of the reactor is controlled at 25±2°C.

[0018] Preferably, in the artificial synthetic wastewater described in S1, the carbon source is provided by CH3COONa, the nitrogen source is provided by NH4Cl and NaNO3, the phosphorus source is provided by KH2PO4, and the pH is adjusted by NaHCO3.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention discloses a method for quickly starting an algae-bacteria granular sludge system for treating anaerobic digestion liquid of piggery wastewater with high ammonia nitrogen and low carbon-nitrogen ratio. The method inoculates algae-bacteria granular sludge cultured with artificially synthesized urban domestic sewage into an SBR reactor of algae-bacteria granular sludge (sequencing batch activated sludge process). Then, the effects of two different TP management strategies on the acclimation of algae-bacteria granular sludge are compared. It is found that controlling the influent NH4 +-N / TP constant management strategy is feasible, but the strategy of controlling the influent TP concentration is not feasible. The feasible startup method is to control the influent COD and NH4 + -N concentration ratio is 3, NH4 + -N and TP concentration ratio is 10, and the influent COD concentration and influent NH4 + The performance of the algae-bacteria granular sludge is enhanced by adjusting the N concentration and influent TP concentration. The acclimation phase is carried out using actual anaerobic digestion liquid from piggery wastewater as the influent water quality, ultimately achieving the startup of the algae-bacteria granular sludge and making it more suitable for the treatment of anaerobic digestion liquid from piggery wastewater. The entire process of implementing the method of the present invention includes comparing two different influent TP management strategies to determine a feasible method for acclimating the algae-bacteria granular sludge with a variable substrate, and then treating the actual anaerobic digestion liquid from piggery wastewater. Ultimately, the ammonia nitrogen concentration in the effluent after the algae-bacteria granular sludge is treated with the actual anaerobic digestion liquid from piggery wastewater without dilution meets the discharge standard, and the removal efficiencies of COD, TN, and TP are as high as 95.65%-99.14%, 66.57%-81.75%, and 78.04%-87.88%, respectively. It can be seen that the method of the present invention can be used for the startup of a sequencing batch reactor for acclimating and treating anaerobic digestion liquid from piggery wastewater.

[0021] Compared with the existing anaerobic digestion liquid treatment process of piggery wastewater, the present invention has the following advantages: (1) The device of the present invention adopts algae-bacteria granular sludge SBR reactor device, the process is simple to run, easy to operate, does not require external carbon source, and the hydraulic retention time is shorter than the existing treatment process. It only takes 16 hours to ensure that the effluent ammonia nitrogen concentration meets the emission standard and maintains a high level of COD, TN and TP removal efficiency. (2) The present invention provides a feasible start-up method for treating anaerobic digestion liquid of piggery wastewater with algae-bacteria granular sludge, and at the same time clarifies the maintenance of NH4 + -The importance of influent TP management strategy with constant N / TP for the domestication of algae-bacteria granular sludge with variable substrates; (3) The present invention provides a method to solve the problem that directly using anaerobic digestion liquid from pig wastewater to domesticate algae-bacteria granular sludge may cause algae to be inhibited by high concentrations of ammonia nitrogen or high TP concentrations to destroy the balance of microbial community structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the SBR test device, in which: 1-LED lamp, 2-rotor flowmeter, 3-aeration pump, 4-sampling port, 5-algae-bacteria granular sludge, 6-water outlet, 7-water outlet peristaltic pump, 8-water outlet bucket, 9-water inlet, 10-water inlet peristaltic pump, 11-water inlet bucket, 12-oxygenated sand and gravel.

[0023] Figure 2The figure shows the nitrogen removal effect of the experimental group 1 reactor using a variable substrate to acclimate algae-bacteria granular sludge during operation. In the figure, stage I is when the influent COD concentration is 300 mg / L and NH4 + -N concentration is 100mg / L, TP concentration is 10mg / L; Phase II is the influent COD concentration is 600mg / L, NH4 + -N concentration is 200mg / L, TP concentration is 20mg / L; stage III is the influent COD concentration is 900mg / L, NH4 + -N concentration is 300mg / L, TP concentration is 30mg / L; Stage IV is the influent COD concentration is 1200mg / L, NH4 + -N concentration is 400mg / L, TP concentration is 40mg / L; stage V is the influent COD concentration is 1500mg / L, NH4 + -N concentration is 500 mg / L, and TP concentration is 50 mg / L.

[0024] Figure 3 The figure shows the nitrogen removal effect of the experimental group 2 reactor using the modified substrate to acclimate algae-bacteria granular sludge during operation. In the figure, stage I is the influent COD concentration of 300 mg / L, NH4 + -N concentration is 100mg / L, TP concentration is 10mg / L; Phase II is the influent COD concentration is 600mg / L, NH4 + -N concentration is 200mg / L, TP concentration is 10mg / L; stage III is the influent COD concentration is 900mg / L, NH4 + -N concentration is 300mg / L, TP concentration is 10mg / L; Stage IV is the influent COD concentration is 1200mg / L, NH4 + -N concentration is 400mg / L, TP concentration is 10mg / L; stage V is the influent COD concentration is 1500mg / L, NH4 + -N concentration is 500 mg / L, and TP concentration is 10 mg / L.

[0025] Figure 4 This is a diagram showing the changes in granular sludge during the operation of the experimental group 2 reactor, which uses a variable substrate to acclimate algae-bacteria granular sludge.

[0026] Figure 5 The figure shows the COD removal effect of the experimental group 1 reactor during operation, which treats the actual anaerobic digestion liquid of pig farm wastewater. In the figure, the influent water quality of stage I is twice the dilution of the actual anaerobic digestion liquid of pig farm wastewater; the influent water quality of stage II is 4 / 3 times the dilution of the actual anaerobic digestion liquid of pig farm wastewater; and the influent water quality of stage III is the undiluted actual anaerobic digestion liquid of pig farm wastewater.

[0027] Figure 6 This figure shows the N removal effect of the experimental group 1 reactor during operation, which treats the actual anaerobic digestion liquid of pig farm wastewater. In the figure, the influent water quality of stage I is twice the dilution of the actual anaerobic digestion liquid of pig farm wastewater; the influent water quality of stage II is 4 / 3 times the dilution of the actual anaerobic digestion liquid of pig farm wastewater; and the influent water quality of stage III is the undiluted actual anaerobic digestion liquid of pig farm wastewater.

[0028] Figure 7 This is a diagram showing the removal effect of P during the operation of the experimental group 1 reactor treating the actual anaerobic digestion liquid of pig farm wastewater; in the figure, the influent water quality of stage I is twice the dilution of the actual anaerobic digestion liquid of pig farm wastewater; the influent water quality of stage II is 4 / 3 times the dilution of the actual anaerobic digestion liquid of pig farm wastewater; the influent water quality of stage III is the undiluted actual anaerobic digestion liquid of pig farm wastewater. DETAILED DESCRIPTION

[0029] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0030] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0031] The algae-bacteria granular sludge described in the embodiment of the present invention was taken from the SBR reactor in the laboratory and was cultured with artificially synthesized urban domestic sewage. The COD concentration of the influent water was 300 mg / L (provided by CH3COONa), NH4 + The nitrogen concentration was 30 mg / L (provided by NH₄Cl), the TP concentration was 10 mg / L (provided by KH₂PO₄), and the pH was 7-8 (adjusted by NaHCO₃). The culture process was intermittently operated, maintaining a 12-hour light / 12-hour dark illumination condition daily, with 3000-4000 lux of illumination provided by LED tubes. The reactor had an 8-hour operating cycle and included five stages: water inlet, anaerobic reaction, aerobic reaction, sedimentation, and drainage. The inlet flow rate was 80 mL / min, the water inlet time was 5 minutes, the anaerobic reaction was unaerated, the anaerobic reaction time was 235 minutes, the aerobic reaction was aerated, and the aeration flow rate was controlled at 3.5-4 L / min. The aerobic reaction time was 235 minutes, the sedimentation time was 2 minutes, and the water exchange ratio in the drainage stage was 50%, with a drainage time of 3 minutes. After 40 days, a muddy-water mixture of algae-bacteria granular sludge cultivated with synthetic municipal sewage was obtained.

[0032] The main components of the artificial synthetic wastewater described in the embodiment of the present invention are CH3COONa, NH4Cl, NaNO3, KH2PO4. If the COD concentration of the influent water is 300 mg / L, NH4 + -N concentration is 100mg / L, TP concentration is 10mg / L, then the corresponding concentrations of CH3COONa, NH4Cl, NaNO3 and KH2PO4 are approximately 385mg / L, 385mg / L, 166mg / L and 44mg / L respectively. + -N concentration and TP concentration are other set values, which can be converted by ratio; the actual anaerobic liquid of piggery wastewater was taken from a large pig farm in Guigang City, Guangxi, and the main water quality indicators are shown in Table 1.

[0033] Table 1 Water quality of anaerobic liquid from actual piggery wastewater

[0034]

[0035]

[0036] Example 1: Construction and startup of an algae-bacteria granular sludge SBR reactor device

[0037] The algae-bacteria granular sludge reactor device is an SBR reactor, such as Figure 1 As shown. The reactor is made of plexiglass, with an inner diameter of 5 cm and a height of 51 cm, a total volume of 1 L, and a working volume of 0.8 L. A water inlet 9 and an inlet valve are located at the bottom of the reactor side. The inlet 9 is connected to an inlet bucket 11 via an inlet peristaltic pump 10. A water outlet 6 and an outlet valve are located 20.4 cm from the bottom of the reactor. The outlet 6 is connected to an outlet bucket 8 via an outlet peristaltic pump 7. A sampling port 4 and a sampling valve are located 40.8 cm from the bottom of the reactor. An oxygen-enhancing gravel 12 is located on the bottom wall of the reactor. This oxygen-enhancing gravel 12 is connected to an external aeration pump 3, with a rotameter 2 located between them. An LED lamp 1 is located 20 cm from the outer wall of the reactor. When the SBR reactor is started, the reactor is inoculated with a sludge-water mixture of algae-bacteria granular sludge 5 grown from synthetic municipal sewage at an initial sludge concentration of 4 g-MLSS / L. Among them, the LED lamp tube 1, the water inlet peristaltic pump 10, the water outlet peristaltic pump 7, and the aeration pump 3 are connected to set the operation time by a timer, the water inlet pipe is connected between the water inlet 9 and the water inlet bucket 11, the water outlet pipe is connected between the water outlet 6 and the water outlet bucket 8, and the aeration pipe is connected between the aeration pump 3 and the oxygen-enriched sand and gravel 12. During the operation of the reactor, the water inlet valve and the water outlet valve are in the open state, and the sampling valve is in the closed state.

[0038] The reactor is operated intermittently, maintaining a 12-hour light / 12-hour dark lighting condition every day. The LED tube provides 3000-4000 lux of light. The reactor's operating cycle is 8 hours, including five stages: water inlet, anaerobic reaction, aerobic reaction, sedimentation, and drainage. During the water inlet stage, a peristaltic pump is used to automatically feed artificial synthetic wastewater. During the inoculation of algae-bacteria granular sludge, the COD concentration of the initial water inlet is controlled at 300 mg / L, and the NH4 + The nitrogen concentration was 100 mg / L, the TP concentration was 10 mg / L, the pH was 7-8, the water inlet time was 5 minutes, and the water flow rate was 80 mL / min. The reaction phase included anaerobic and aerobic reactions. The anaerobic reaction was conducted without aeration and lasted 235 minutes. The aerobic reaction was conducted using an aeration pump to compress air and aerate the sand and gravel bottom. The aeration flow rate was controlled by a rotor flowmeter at 3.5-4 L / min. The aerobic reaction lasted 235 minutes. The sedimentation time was 2 minutes. The drainage phase used an outlet peristaltic pump for automatic drainage, with a water exchange ratio of 50% and a drainage time of 3 minutes. The reactor operating temperature was controlled at 25±2°C.

[0039] Example 2: Modifying the substrate to acclimate algae-bacteria granular sludge

[0040] After searching relevant literature, the COD concentration of anaerobic liquid of piggery wastewater is generally 240-2868.4 mg / L, NH4 + -N concentration is 140-1100 mg / L, TP concentration is 8.7-50 mg / L, COD / NH4 + -N is 1-3. In order to compare the effects of two different influent TP management strategies on the acclimation of algae-bacteria granular sludge, experimental group 1 and experimental group 2 were set up. The influent NH4 + -N / TP remained unchanged, and the influent TP concentration of experimental group 2 was kept at 10 mg / L. COD / NH4 of the synthetic wastewater in experimental group 1 + -N selects 3, COD concentration is 1500mg / L, TP concentration is 50mg / L, ammonia nitrogen concentration is 500mg / L, NH4 + -N / TP is 10; COD / NH4 of the artificial synthetic wastewater in experimental group 2 + -N is selected as 3, COD concentration is 1500 mg / L, ammonia nitrogen concentration is 500 mg / L, and TP concentration is 10 mg / L.

[0041] The SBR reactors built in Example 1 (two in total, divided into experimental group 1 and experimental group 2) were fed with artificial synthetic wastewater containing a carbon source, a nitrogen source, and a phosphorus source for sludge acclimation. The acclimation period of experimental group 1 included five stages, namely stage I, stage II, stage III, stage IV, and stage V. Stage I was from the 1st day to the 20th day, stage II was from the 21st day to the 50th day, stage III was from the 51st day to the 80th day, stage IV was from the 81st day to the 110th day, and stage V was from the 111th day to the 154th day. The influent COD concentration and influent NH4 + -N concentration and influent TP concentration to enhance the performance of algae-bacteria granular sludge, where the COD concentration gradient is 300, 600, 900, 1200, 1500 mg / L, NH4 + -N concentration gradient is 100, 200, 300, 400, 500 mg / L, TP concentration gradient is 10, 20, 30, 40, 50 mg / L. The acclimatization period of experimental group 2 includes four stages, namely stage I, stage II, stage III, and stage IV. Stage I is from the 1st day to the 24th day, stage II is from the 25th day to the 54th day, stage III is from the 55th day to the 84th day, and stage IV is from the 85th day to the 114th day. The influent COD concentration and influent NH4 + -N concentration to enhance the performance of algae-bacteria granular sludge, where the COD concentration gradient is 300, 600, 900, 1200 mg / L, NH4 + -N concentration gradient is 100, 200, 300, 400 mg / L, TP concentration is kept constant at 10 mg / L. The division criteria of the above stages are: in each gradient acclimation stage, when the effluent NH4 + The next gradient acclimation can only be entered when the -N removal rate stably reaches above 95%.

[0042] The artificial synthetic wastewater described in this embodiment contains a carbon source, a nitrogen source, and a phosphorus source, wherein the carbon source is provided by CH3COONa, the nitrogen source is provided by NH4Cl and NaNO3, and the phosphorus source is provided by KH2PO4. The concentrations of CH3COONa, NH4Cl, NaNO3, and KH2PO4 in the artificial synthetic wastewater are determined by the set influent water quality. For example, the COD concentration of the influent water quality in stage I is 300 mg / L, and the NH4 + -N concentration is 100mg / L, TP concentration is 10mg / L, then the corresponding concentrations of CH3COONa, NH4Cl, NaNO3 and KH2PO4 are approximately 385mg / L, 385mg / L, 166mg / L and 44mg / L respectively. +-N concentration and TP concentration are other set values ​​and can be converted by the above ratio. Other operating conditions are set as follows: the inlet pH is 7-8, the reactor operation cycle is 8h, each cycle includes five stages: water inlet, anaerobic reaction, aerobic reaction, precipitation and drainage. The reactor outlet water is taken from the outlet bucket once every two days and placed in a 10mL centrifuge tube, stored in a 4°C refrigerator, and the reactor outlet COD, nitrite nitrogen, nitrate nitrogen, ammonia nitrogen and total phosphorus concentrations are measured on the same day. The total nitrogen concentration in this embodiment is the sum of the concentrations of nitrite nitrogen, nitrate nitrogen and ammonia nitrogen, and the total phosphorus concentration is the phosphate concentration. The inlet water needs to be replaced every day to ensure the stability of the inlet water quality.

[0043] Figure 2 The nitrogen removal during the operation of the experimental group 1 reactor of the modified substrate acclimated algae-bacteria granular sludge is shown in the figure. The influent COD concentration of stage I is 300 mg / L, NH4 + -N concentration is 100mg / L, TP concentration is 10mg / L; the influent COD concentration of stage II is 600mg / L, NH4 + -N concentration is 200mg / L, TP concentration is 20mg / L; the influent COD concentration of stage III is 900mg / L, NH4 + -N concentration is 300mg / L, TP concentration is 30mg / L; the influent COD concentration of stage IV is 1200mg / L, NH4 + -N concentration is 400mg / L, TP concentration is 40mg / L; the influent COD concentration of stage V is 1500mg / L, NH4 + -N concentration is 500 mg / L, and TP concentration is 50 mg / L.

[0044] from Figure 2 It can be seen that at the beginning of stage I, the algae-bacteria granular sludge has a significant effect on the NH4 + The removal rate of -N is only about 60%, and the removal rate of TN is only about 10%. This is because the algae-bacteria granular sludge was just cultured from artificially synthesized low-ammonia nitrogen urban domestic sewage, and when it was inoculated into another artificially synthesized high-ammonia nitrogen wastewater, this high-ammonia nitrogen wastewater would initially inhibit the denitrification performance of the algae-bacteria granular sludge. Later, the algae-bacteria granular sludge gradually adapted to the COD concentration of 300 mg / L and NH4 + -N concentration is 100mg / L, TP concentration is 10mg / L, and the NH4 + -N removal rate increased and stabilized at about 95%, and TN removal rate increased and stabilized at about 90%. In the early stage of phase II, the algae-bacteria granular sludge had a great impact on the NH4 + -N removal rate dropped to about 80%, and TN removal rate even dropped to about 4% one day, because the influent water quality changed, COD concentration increased from 300mg / L to 600mg / L, NH4+ -N concentration increased from 100mg / L to 200mg / L, TP concentration increased from 10mg / L to 20mg / L, algae-bacteria granular sludge has not yet adapted to the new water quality, and gradually adapted to the new water quality in the later period, NH4 + -N removal rate increased and stabilized at about 97%, TN removal rate increased and stabilized at about 64%. Stage III algae-bacteria granular sludge to NH4 + -N removal rate and TN removal rate changes are similar to those in stage I and stage II. In the later stage, they gradually adapt to the new water quality. + -N removal rate increased and stabilized at about 96%, TN removal rate increased and stabilized at about 74%. From stage IV to stage V, COD concentration increased from 1200mg / L to 1500mg / L, NH4 + -N concentration increased from 400mg / L to 500mg / L, TP concentration increased from 40mg / L to 50mg / L, NH4 + -N removal rate and TN removal rate did not change much, and maintained at about 98% and 77% respectively. From the above analysis, it can be seen that the influent water quality control COD / NH4 + -N=3,NH4 + -N / TP=10, and continuously increase the influent COD concentration and influent NH4 + The method of enhancing the performance of algae-bacteria granular sludge by -N concentration and influent TP concentration is feasible.

[0045] Figure 3 The figure shows the nitrogen removal effect of the experimental group 2 reactor using the modified substrate to acclimate algae-bacteria granular sludge during operation. In the figure, stage I is the influent COD concentration of 300 mg / L, NH4 + -N concentration is 100mg / L, TP concentration is 3mg / L; Phase II is the influent COD concentration is 600mg / L, NH4 + -N concentration is 200mg / L, TP concentration is 10mg / L; stage III is the influent COD concentration is 900mg / L, NH4 + -N concentration is 300mg / L, TP concentration is 10mg / L; Stage IV is the influent COD concentration is 1200mg / L, NH4 + -N concentration is 400mg / L, TP concentration is 10mg / L; stage V is the influent COD concentration is 1500mg / L, NH4 + -N concentration is 500 mg / L, and TP concentration is 10 mg / L.

[0046] from Figure 3 It can be seen that the NH4 +-N and TN removal rates were stable at more than 96% and 65%-70% respectively, and the NH4 + -N and TN removal rates fluctuated slightly, remaining stable at 92%-99% and above 88% respectively, but the NH4 + -N and TN removal rates changed greatly, dropping to 38%-44% and 42%-47% respectively, and the effluent NH4 + -N removal rate did not reach more than 95%, indicating that the influent water quality controls COD / NH4 + -N=3, TP concentration is 10mg / L, and the method of continuously increasing the influent COD concentration and influent ammonia nitrogen concentration to enhance the performance of algae-bacteria granular sludge is not feasible. Figure 4 It can be seen that the algae-bacteria granular sludge in the experimental group 2 reactor using variable substrate to acclimate algae-bacteria granular sludge did not change significantly from stage I to stage III, but changed significantly in stage IV. Most of the granular sludge turned white, which may be related to the deterioration of the system's denitrification performance.

[0047] In summary, the reactor in experimental group 1 controls the influent NH4 + -The TP management strategy of keeping the N / TP constant is feasible, and the stage of changing the substrate to acclimate the algae-bacteria granular sludge is successful. The experimental group 1 reactor can enter the implementation stage of treating the actual anaerobic digestion liquid of piggery wastewater with algae-bacteria granular sludge. The strategy of keeping the influent TP concentration constant in the experimental group 2 reactor is not feasible, and the stage of changing the substrate to acclimate the algae-bacteria granular sludge fails, and the operation of the experimental group 2 reactor is ended. Therefore, NH4 + -N / TP is the key factor for the successful startup of algae-bacteria granular sludge system.

[0048] Example 3: Treatment of anaerobic digestion liquid from actual piggery wastewater using algae-bacteria granular sludge

[0049] The effluent from the actual piggery wastewater anaerobic digester was used as the inlet water for the reactor in experimental group 1, and NH4 + -N concentration is 480-560mg / L, NO2 - -N concentration is 0-1mg / L, NO3 --N=20-40mg / L, COD concentration is 1300-1500mg / L, TP concentration is 20-30mg / L, and pH is 7-8. The reactor inlet adopts a step-by-step water strategy: the actual anaerobic digestion liquid of piggery wastewater is first diluted twice and run for a period of time, then diluted 4 / 3 times and run for a period of time, and finally run for a period of time without dilution; during the operation of the reactor, the aeration gas flow rate is adjusted according to the effluent ammonia nitrogen concentration, and the aeration gas flow rate is adjusted within the range of 3.5-4L / min. In each step of the water inlet strategy, the next water inlet strategy can only be entered when the effluent ammonia nitrogen removal rate is stable at more than 95%; when the reactor inlet water is the actual anaerobic digestion liquid of piggery wastewater without dilution, and the effluent ammonia nitrogen removal rate is stable at more than 95%, it is considered that the algae-bacteria granular sludge for treating the anaerobic digestion liquid of piggery wastewater has been successfully started.

[0050] Figure 5 、 Figure 6 and Figure 7 The COD, N and P removal effects of the algae-bacteria granular sludge system during operation were respectively treated with the actual anaerobic digestion liquid of piggery wastewater. In the figure, the influent of stage I was treated with 2 times dilution of the actual anaerobic digestion liquid of piggery wastewater. The reactor was operated under such conditions for 14 days, and the effluent COD, NH4 + -N, TN and TP concentrations were 168-218 mg / L, 5.65-6.81 mg / L, 108-132 mg / L and 8.74-10.92 mg / L, respectively. COD removal rate, NH4 + -N removal rate, TN removal rate and TP removal rate are stable at 70.54%-76.2%, 96.99%-97.5%, 45.3%-58.38% and 30.89%-44.7% respectively. The influent of Phase II is the anaerobic digestion liquid of actual piggery wastewater diluted 4 / 3 times and maintained under such conditions for 20 days. The effluent COD, NH4 + -N, TN and TP concentrations were 192-310 mg / L, 5.94-11.18 mg / L, 126.56-140.11 mg / L and 7.91-10.09 mg / L, respectively. COD removal rate, NH4 + -N removal rate, TN removal rate and TP removal rate are stable at 71.77%-81.43%, 96.94%-98.42%, 64.97%-68.13% and 46.08%-57.97% respectively. It can be found that compared with stage I, the COD removal rate and NH4 +-N removal rate did not change much, while TN removal rate and TP removal rate increased significantly, indicating that the performance of algae-bacteria granules in removing organic matter and removing nitrogen and phosphorus in stage II remained stable. In stage III, the anaerobic digestion liquid of actual pig wastewater without dilution was directly used as the reactor water. After 52 days of operation, it was found that the COD removal rate and NH4 + -N removal rate, TN removal rate and TP removal rate did not change much, and were stable at 78.04%-87.88%, 95.65%-99.14%, 66.57%-81.75% and 78.04%-87.88% respectively. The effluent COD and NH4 + The concentrations of -N, TN, and TP are 160-308 mg / L, 4.78-20.5 mg / L, 107.22-172.82 mg / L, and 3.44-8.94 mg / L, respectively. The criteria for this stage are: only when the effluent ammonia nitrogen removal rate is stabilized above 95% can the next water inflow strategy be entered.

[0051] From the above analysis, it can be seen that after the algae-bacteria granular sludge is acclimated by the startup method of the present invention, it is used to treat the actual anaerobic liquid of aquaculture wastewater, which can ensure that the effluent ammonia nitrogen concentration meets the emission standard and ensure that the algae-bacteria granular sludge maintains a high level of COD, TN and TP removal efficiency, indicating that the algae-bacteria granular sludge of the present invention is successfully started to treat the anaerobic digestion liquid of pig wastewater.

[0052] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A rapid start-up method for treating anaerobic digestion liquid of high-ammonia-nitrogen and low-carbon-nitrogen ratio piggery wastewater using an algae-bacteria granular sludge system, characterized in that: The following steps are involved: S1, the stage of changing substrate to acclimate algae-bacteria granular sludge: inoculate algae-bacteria granular sludge into SBR reactor, then introduce artificial synthetic wastewater containing carbon source, nitrogen source and phosphorus source to acclimate the sludge, and control the influent NH4 + -N / TP constant management strategy to control influent COD / NH4 + -N=3,NH4 + -N / TP=10, influent pH is 7-8, then continuously increase influent COD concentration, influent NH4 + -N concentration and influent TP concentration to enhance the performance of algae-bacteria granular sludge; in each gradient acclimation stage, when the effluent NH4 + -N removal rate must reach more than 95% to enter the next gradient acclimatization, when the influent COD concentration is 1500mg / L, the influent NH4 + When the -N concentration is 500mg / L and the inlet TP concentration is 50mg / L, the outlet NH4 + -N removal rate has reached more than 95% stably, which means that the stage of substrate transformation and acclimation of algae and bacteria granular sludge has been successful and entered the stage of actual piggery wastewater anaerobic digestion liquid treatment; therefore, NH4 + -N / TP is the key factor for the successful start-up of algae-bacteria granular sludge system; S2. Actual piggery wastewater anaerobic digestion liquid treatment start-up stage: The effluent from the actual piggery wastewater anaerobic digestion tank is used as the inlet water quality of the SBR reactor for the implementation stage of acclimatization, NH4 + -N concentration is 480-560mg / L, COD concentration is 1300-1500mg / L, TP concentration is 20-30mg / L, pH is 7-8, and the reactor inlet adopts a step-by-step water strategy: the actual anaerobic digestate of piggery wastewater is first diluted twice and run for a period of time, then diluted 4 / 3 times and run for a period of time, and finally run without dilution for a period of time; In each step of the water inlet strategy, when the outlet NH4 + -N removal rate is stable above 95%, then the next water inlet strategy can be entered; when the reactor inlet water is the actual anaerobic digestion liquid of undiluted pig wastewater, and the effluent NH4 + When the -N removal rate is stable at above 95%, it is considered that the algae-bacteria granular sludge for treating anaerobic digestion liquid of piggery wastewater is successfully started.

2. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 1, characterized in that: The SBR reactor is made of organic glass, and a water inlet and a water inlet valve are provided at the bottom of the reactor side wall, and the water inlet is connected to the water inlet bucket through a water inlet peristaltic pump. A water outlet and a water outlet valve are provided in the middle of the reactor side wall, and the water outlet is connected to the water outlet bucket through a water outlet peristaltic pump. A sampling port and a sampling valve are provided at the upper position of the reactor side wall, and oxygen-enriched sand and gravel are provided on the bottom wall of the reactor, and the oxygen-enriched sand and gravel are connected to an external aeration pump, and a rotor flowmeter is provided between the oxygen-enriched sand and gravel and the aeration pump, and an LED lamp is provided near the outer wall of the reactor.

3. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 2, characterized in that: The LED lamp tube, water inlet peristaltic pump, water outlet peristaltic pump, and aeration pump are connected to a timer to set the operation time. The water inlet pipe is connected between the water inlet and the water inlet bucket, the water outlet pipe is connected between the water outlet and the water outlet bucket, and the aeration pipe is connected between the aeration pump and the oxygen-enriched sand and gravel. During the operation of the reactor, the water inlet valve and the water outlet valve are in the open state, and the sampling valve is in the closed state.

4. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 1, characterized in that: The acclimation period of S1 includes five stages, namely stage I, stage II, stage III, stage IV, and stage V. Stage I is from the 1st day to the 20th day, stage II is from the 21st day to the 50th day, stage III is from the 51st day to the 80th day, stage IV is from the 81st day to the 110th day, and stage V is from the 111th day to the 154th day. The influent COD concentration and influent NH4 + -N concentration and influent TP concentration to enhance the performance of algae-bacteria granular sludge, where the COD concentration gradient is 300, 600, 900, 1200, 1500 mg / L, NH4 + The -N concentration gradient was 100, 200, 300, 400, and 500 mg / L, and the TP concentration gradient was 10, 20, 30, 40, and 50 mg / L.

5. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by an algae-bacteria granular sludge system according to claim 1, characterized in that: The treatment stage of S2 consists of three stages. Stage I is the operation stage in which the actual anaerobic digestate of pig farm wastewater is diluted twice, and it runs for a total of 14 days. Stage II is the operation stage in which the actual anaerobic digestate of pig farm wastewater is diluted 4 / 3 times, and it runs for a total of 20 days. Stage III is the operation stage in which the actual anaerobic digestate of pig farm wastewater is not diluted, and it runs for a total of 52 days.

6. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 1, characterized in that: In S1, the SBR reactor is inoculated with a sludge-water mixture of algae-bacteria granular sludge cultured with artificially synthesized urban domestic sewage at an initial sludge concentration of 4 g-MLSS / L.

7. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 1, characterized in that: During S1 and S2, the reactor was operated intermittently, maintaining a lighting condition of 12 hours of light / 12 hours of darkness every day, and the LED tube provided 3000-4000 lux of light. The operating cycle of the reactor was 8 hours, including five stages: water inlet, anaerobic reaction, aerobic reaction, sedimentation and drainage. Among them, the water inlet flow rate was 80 mL / min, the water inlet time was 5 minutes, the anaerobic reaction was not aerated, the anaerobic reaction time was 235 minutes, the aerobic reaction was aerated, and the aeration flow rate was controlled at 3.5-4 L / min, the aerobic reaction time was 235 minutes, the sedimentation time was 2 minutes, the water exchange ratio in the drainage stage was 50%, and the drainage time was 3 minutes.

8. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 1, characterized in that: During S1 and S2, the reactor temperature was controlled at 25±2°C.

9. The rapid start-up method for treating anaerobic digestion liquid of high ammonia nitrogen and low carbon nitrogen ratio piggery wastewater by using an algae-bacteria granular sludge system according to claim 1, characterized in that: In the artificial synthetic wastewater described in S1, the carbon source is provided by CH3COONa, the nitrogen source is provided by NH4Cl and NaNO3, the phosphorus source is provided by KH2PO4, and the pH is adjusted by NaHCO3.

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