Method for enhancing abundance of microbial populations in sludge and removing nitrogen and phosphorus in sewage by using biochar

Abstract

The invention relates to the technical field of nitrogen and phosphorus removal of sewage, and particularly discloses a method for enhancing abundance of microbial populations in sludge and nitrogen and phosphorus removal of sewage by using biochar, which comprises five stages of water feeding, aeration, precipitation, drainage and standing, and also comprises the following steps: step 1, in a water feeding stage, starting a water feeding pump, sewage enters the aerobic granular sludge reactor through a uniform water distributor at the bottom of the reactor; according to the invention, residual charcoal powder generated by microwave pyrolysis of an urban sewage treatment plant is used as a carrier inner core, and the change conditions of sludge properties and water treatment capacity in the granulation process of an SBR reactor added with two sludge carriers, namely CaO-sludge charcoal powder (R4) and Fe2O3-sludge charcoal powder (R5), are compared respectively; the advantages and disadvantages of different types of carriers can be evaluated, the carriers suitable for rapid starting of the aerobic granular sludge process and long-term stability of granular forming are screened out, and technical support and theoretical basis are provided for research, development, popularization and application of the aerobic granular sludge process.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage denitrification and phosphorus removal, and specifically relates to a method for enhancing the abundance of microbial populations in sludge and denitrification and phosphorus removal in sewage by biochar. Background Art

[0002] Traditional sewage treatment processes have the problems of large footprint, low effluent effect, and large sludge production, which can no longer meet the needs of current social development. It is a general trend to promote more efficient and energy-saving sewage treatment processes. Aerobic granular sludge process has attracted much attention due to its advantages of good effluent effect, small footprint, sludge-water separation, simultaneous denitrification and phosphorus removal, and small amount of sludge discharge. It is hailed as the most promising biological sewage treatment process in the 21st century. However, the long granulation time, poor granule stability and unclear mechanism of this process limit its further development. If the technical bottlenecks of long granulation time and poor stability can be changed, the practical application of this technology will be greatly promoted. Due to the different effects of the characteristics of the carrier itself on the physiological and biochemical activities of microorganisms, different carriers have different promoting effects on the aerobic granulation process of sludge. Therefore, a method for enhancing the abundance of microbial populations in sludge and denitrification and phosphorus removal in sewage by biochar is proposed.

[0003] In order to further explore the effect of adding sludge-based biochar carrier on aerobic granular sludge granulation and pollutant removal, the biochar powder produced by microwave pyrolysis of residual wastewater from urban sewage treatment plants was used as the carrier core. The changes in sludge properties and water treatment capacity during the granulation process of SBR reactors with two sludge carriers, CaO-sludge biochar powder (R4) and Fe2O3-sludge biochar powder (R5), were compared. The operation results of the reactors without added carrier materials (R1), chitosan (R2), and zeolite powder (R3) in the previous study were compared and analyzed. The performance of different carriers in the aerobic sludge granulation process (sludge change The research aims to investigate the degradation status of aerobic granular sludge, the effect of sewage treatment, the changes in the secretion of extracellular polymers of microorganisms, and the performance of mature aerobic granular sludge (degradation rules of pollutants within the cycle, particle morphology, and community structure). The research aims to deeply explore and reveal the different effects of the characteristics of different carriers on the granulation process of aerobic granular sludge. The advantages and disadvantages of different types of carriers are evaluated, and carriers suitable for the rapid start-up of aerobic granular sludge process and long-term stability of particle formation are selected. New ways to apply sludge-based biochar to sewage treatment are explored. The interaction mechanism between sludge granulation and carriers after sludge formation and microorganisms is analyzed, so as to provide technical support and theoretical basis for the research and development and promotion and application of aerobic granular sludge process. Summary of the invention

[0004] The object of the present invention is to provide a method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by using biochar, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by biochar, characterized in that it includes five stages: water intake, aeration, sedimentation, drainage and standing, and also includes:

[0007] Step 1: During the water inlet stage, the water inlet pump is turned on, and the sewage enters the aerobic granular sludge reactor through the uniform water distributor at the bottom of the reactor. The water inlet flow rate is controlled by the electromagnetic valve and monitored by the flow meter, and a high flow rate is maintained to make the water inflow in the reactor upflow;

[0008] Step 2: During the aeration phase, after the water is inletted, the water inlet pump is turned off and the blower is turned on to allow air to enter the reactor through the microporous aerator at the bottom of the reactor. The air flow rate is monitored in real time by the rotor flow meter.

[0009] Step 3: Sedimentation stage: After aeration is completed, the aerator is turned off and the sludge begins to settle;

[0010] Step 4: During the water discharge phase, open the drain valve to drain water;

[0011] Step 5: During the static stage, after the clean water and a small amount of sludge flocs on the top of the drain valve are discharged, repeat the operation from step 1.

[0012] As can be seen from the above, the present invention uses the biochar powder produced by microwave pyrolysis of the residual biochar in the urban sewage treatment plant as the core of the carrier, and compares the changes in the properties of the sludge and the water treatment capacity during the granulation process of the SBR reactor with two sludge carriers, namely, CaO-sludge biochar powder (R4) and Fe2O3-sludge biochar powder (R5), and compares the operation results of the reactor without adding carrier material (R1), chitosan (R2), and zeolite powder (R3) in the previous study. By analyzing the performance of different carriers in the aerobic granulation process of sludge (sludge changes, sewage treatment effect, microbial extracellular The authors investigated the performance of mature aerobic granular sludge (pollutant degradation patterns, particle morphology, and community structure within the cycle) and the characteristics of different carriers themselves that have different effects on the aerobic granular sludge granulation process, evaluated the advantages and disadvantages of different types of carriers, screened out carriers suitable for rapid start-up of aerobic granular sludge process and long-term stability of particle formation, explored new ways to apply sludge-based biochar to sewage treatment, analyzed the interaction mechanism between sludge granulation and carriers and microorganisms after sludge formation, and provided technical support and theoretical basis for the research and development and promotion and application of aerobic granular sludge process.

[0013] Preferably, the upflow water inflow time inside the reactor is 5 minutes.

[0014] Preferably, the aeration duration of the aeration stage is 310 min, and the aeration time of the aeration stage gradually increases to 10 min, 12 min, 15 min and 17 min.

[0015] Preferably, the sedimentation time in the sludge acclimation stage is 20 minutes, and over time, the sedimentation time in the sludge acclimation stage is gradually reduced to 15 minutes, 10 minutes, 8 minutes and 5 minutes.

[0016] Preferably, the drain valve adopts a drainage ratio of 50%, and adopts a drainage ratio of 75% when the inlet COD is lower than 150 mg / l. The drainage flow rate is controlled by an electromagnetic valve, and the drainage time is 5 minutes.

[0017] Through the coordinated setting of the above steps, the process of removing nitrogen and phosphorus from sewage by using the five stages of water inlet, aeration, sedimentation, drainage and standing to enhance the abundance of microbial populations in biochar-enhanced sludge has the following benefits:

[0018] In the water inlet stage, sewage is introduced into the treatment system. At this time, biochar can be used as an adsorbent to absorb pollutants such as organic matter and heavy metal ions in sewage by utilizing its high porosity and large specific surface area, thus reducing the burden for subsequent treatment stages. At the same time, the introduction of biochar also provides abundant attachment space for microorganisms, which is conducive to the growth of microbial populations and the improvement of their abundance.

[0019] During the aeration stage, air is introduced into the sewage to provide sufficient oxygen for microorganisms and promote their metabolic activities. The presence of biochar not only enhances the adsorption capacity of sludge, but also provides a better growth environment for microorganisms. In addition, the functional groups on the surface of biochar can react with organic matter in sewage to accelerate the degradation of organic matter, which helps to improve the efficiency of nitrogen and phosphorus removal in sewage, because the removal of nitrogen and phosphorus is often closely related to the degradation of organic matter.

[0020] In the sedimentation stage, sludge and water are separated, and impurities such as suspended matter and colloids in sewage settle to the bottom under the action of gravity. The introduction of biochar helps to improve the sedimentation performance of sludge, making it more compact and easier to separate. At the same time, biochar can also adsorb some soluble organic and inorganic matter to further purify water quality.

[0021] The drainage stage is to discharge the treated clean water out of the system. At this time, the adsorption effect of biochar has removed most of the pollutants, which significantly improves the quality of the discharged water. In addition, biochar can also promote the absorption and utilization of nutrients such as nitrogen and phosphorus by microorganisms, thereby reducing the residual amount of these elements in the sewage.

[0022] During the static stage, the system is in a relatively static state, which is conducive to the further growth and reproduction of microorganisms. The presence of biochar provides a stable attachment matrix for microorganisms, which is conducive to the continuous improvement of the abundance of microbial populations. At the same time, the static stage also helps the biochar to fully contact and react with pollutants in the sewage, further improving the efficiency of nitrogen and phosphorus removal.

[0023] In summary, the introduction of biochar enhances the adsorption capacity of sludge and the metabolic activity of microorganisms, which helps to accelerate the removal process of pollutants such as nitrogen and phosphorus; through multiple mechanisms such as adsorption, oxidation and biodegradation, biochar can significantly reduce the concentration of pollutants such as organic matter and heavy metal ions in sewage, and improve the effluent quality; biochar provides rich attachment space and growth environment for microorganisms, which is conducive to the growth and abundance of microbial populations; biochar has good regeneration performance and can be reused, reducing long-term operating costs. At the same time, the introduction of biochar may also reduce the use of chemical agents, further saving costs.

[0024] Preferably, the standing time of the standing stage is 20 minutes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention uses the biochar powder produced by microwave pyrolysis of the residual biochar in the urban sewage treatment plant as the core of the carrier, and compares the changes in the properties of the sludge and the water treatment capacity during the granulation process of the SBR reactor with two sludge carriers, namely, CaO-sludge biochar powder (R4) and Fe2O3-sludge biochar powder (R5). The results are compared with the operation results of the reactors without carrier materials (R1), chitosan (R2), and zeolite powder (R3) in the previous study. By analyzing the performance of different carriers in the aerobic granulation process of sludge (sludge changes, sewage treatment effect, microbial extracellular polymers secretion changes) and the performance of mature aerobic granular sludge (pollutant degradation rules, particle morphology, and community structure within the cycle), deeply explore and reveal the different effects of the characteristics of different carriers on the aerobic granular sludge granulation process, evaluate the advantages and disadvantages of different types of carriers, screen out carriers suitable for rapid start-up of aerobic granular sludge process and long-term stability of granule formation, explore new ways to apply sludge-based biochar to sewage treatment, analyze the interaction mechanism between sludge granulation and carriers after sludge formation and microorganisms, and provide technical support and theoretical basis for the research and development and promotion and application of aerobic granular sludge process;

[0027] The introduction of biochar enhances the adsorption capacity of sludge and the metabolic activity of microorganisms, which helps to accelerate the removal of pollutants such as nitrogen and phosphorus; through multiple mechanisms such as adsorption, oxidation and biodegradation, biochar can significantly reduce the concentration of pollutants such as organic matter and heavy metal ions in sewage, and improve the effluent quality; biochar provides abundant attachment space and growth environment for microorganisms, which is conducive to the growth and abundance of microbial populations; biochar has good regeneration performance and can be reused, reducing long-term operating costs. At the same time, the introduction of biochar may also reduce the use of chemical agents, further saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0030] A method for enhancing the abundance of microbial populations in sludge and denitrification and phosphorus removal from sewage by biochar, comprising: A method for enhancing the abundance of microbial populations in sludge and denitrification and phosphorus removal from sewage by biochar, characterized in that it comprises five stages of water intake, aeration, sedimentation, drainage and standing, and also comprises:

[0031] Step 1: During the water inlet stage, the water inlet pump is turned on, and the sewage enters the aerobic granular sludge reactor through the uniform water distributor at the bottom of the reactor. The water inlet flow rate is controlled by the electromagnetic valve and monitored by the flow meter, and a high flow rate is maintained to make the reactor flow upflow, and the water inlet time is 5 minutes;

[0032] Step 2: During the aeration phase, after the water is inletted, the water inlet pump is turned off and the blower is turned on to allow air to enter the reactor through the microporous aerator at the bottom of the reactor. The air flow rate is monitored in real time by the rotor flowmeter. The aeration time is 310 min, and the time is gradually increased by 10 min, 12 min, 15 min and 17 min.

[0033] Step 3: Settling stage: after aeration is completed, turn off the aerator and the sludge begins to settle. The settling time in the sludge acclimation stage is 20 minutes, which gradually decreases to 15 minutes, 10 minutes, 8 minutes, and 5 minutes. The extra time is compensated for the aeration time accordingly.

[0034] Step 4: In the water discharge stage, open the drain valve, generally use a 50% drainage ratio, and use a 75% drainage ratio when the inlet COD is lower than 150 mg / l. The drainage flow rate is controlled by the electromagnetic valve, and the drainage time is generally 5 minutes;

[0035] Step 5: During the static stage, after the clean water and a small amount of sludge flocs on the top of the drain valve are discharged, let it stand for 20 minutes, thus completing a cycle, and then repeat the operation from step 1;

[0036] The operating parameters of the SBR reactor at different stages are shown in the following table:

[0037]

[0038]

[0039] The present invention is carried out in two stages. The first stage is the preliminary exploratory test stage. After the reactor is started, different aerobic granular sludge carriers are added to the three organic glass cylinders SBR1, SBR2 and SBR3 respectively. In the first stage, on the second day of the operation of the reactor, 100 ml of broken aerobic granular sludge is added to the SBR1 reactor, 10 g of chitosan is added to the SBR1 reactor, and 10 g of zeolite powder is added to the SBR1 reactor as a carrier of aerobic granular sludge, which is used to strengthen particle formation and reactor denitrification and phosphorus removal. The three SBR reaction devices are placed in the room. The equipment operates at a temperature of 24.5℃, and the pH is maintained between 7 and 8. One cycle of the equipment includes five stages: water intake, aeration, sedimentation, drainage, and standing. In the first four days of equipment operation, in order to accelerate the start of sludge granulation, a 3-hour cycle is adopted, including 5 minutes of water intake, 135 minutes of aeration, 15 minutes of sedimentation, 5 minutes of drainage, and 20 minutes of standing. After that, the operation cycle becomes 6 hours, 5 minutes of water intake, 310 minutes of aeration, and the sedimentation time decreases from 15 minutes. The rest of the time is compensated for the aeration stage, 5 minutes of drainage, and 20 minutes of standing.

[0040] In the second stage, the reactor was re-operated, 10g CaO-biochar powder was added to the SBR4 reactor, 10g Fe2O3-biochar powder was added to the SBR5 reactor, and SBR6 was used as a spare reactor to maintain the smooth progress of the second stage experiment. The operating conditions of SBR4 and SBR5 in the second stage were the same as those of the reactors in the first stage, and the reaction time of each section in the cycle was also the same. The equipment was operated for the first four days with a cycle of 3h, including 5min of water intake, 135min of aeration, 15min of sedimentation, 5min of drainage, and 20min of standing. Starting from the 5th day, the operating cycle became 6h, including 5min of water intake, 310min of aeration, and the sedimentation time decreased from 15min and compensated for the aeration stage, 5min of drainage, and 20min of standing.

[0041] As can be seen from the above, the present invention uses the biochar powder produced by microwave pyrolysis of the residual biochar in the urban sewage treatment plant as the core of the carrier, and compares the changes in the properties of the sludge and the water treatment capacity during the granulation process of the SBR reactor with two sludge carriers, namely, CaO-sludge biochar powder (R4) and Fe2O3-sludge biochar powder (R5), and compares the operation results of the reactor without adding carrier material (R1), chitosan (R2), and zeolite powder (R3) in the previous study. By analyzing the performance of different carriers in the aerobic granulation process of sludge (sludge changes, sewage treatment effect, microbial extracellular The authors investigated the performance of mature aerobic granular sludge (pollutant degradation patterns, particle morphology, and community structure within the cycle) and the characteristics of different carriers themselves that have different effects on the aerobic granular sludge granulation process, evaluated the advantages and disadvantages of different types of carriers, screened out carriers suitable for rapid start-up of aerobic granular sludge process and long-term stability of particle formation, explored new ways to apply sludge-based biochar to sewage treatment, analyzed the interaction mechanism between sludge granulation and carriers and microorganisms after sludge formation, and provided technical support and theoretical basis for the research and development and promotion and application of aerobic granular sludge process.

[0042] Through the coordinated setting of the above steps, the process of removing nitrogen and phosphorus from sewage by using the five stages of water inlet, aeration, sedimentation, drainage and standing to enhance the abundance of microbial populations in biochar-enhanced sludge has the following benefits:

[0043] In the water inlet stage, sewage is introduced into the treatment system. At this time, biochar can be used as an adsorbent to absorb pollutants such as organic matter and heavy metal ions in sewage by utilizing its high porosity and large specific surface area, thus reducing the burden for subsequent treatment stages. At the same time, the introduction of biochar also provides abundant attachment space for microorganisms, which is conducive to the growth of microbial populations and the improvement of their abundance.

[0044] During the aeration stage, air is introduced into the sewage to provide sufficient oxygen for microorganisms and promote their metabolic activities. The presence of biochar not only enhances the adsorption capacity of sludge, but also provides a better growth environment for microorganisms. In addition, the functional groups on the surface of biochar can react with organic matter in sewage to accelerate the degradation of organic matter, which helps to improve the efficiency of nitrogen and phosphorus removal in sewage, because the removal of nitrogen and phosphorus is often closely related to the degradation of organic matter.

[0045] In the sedimentation stage, sludge and water are separated, and impurities such as suspended matter and colloids in sewage settle to the bottom under the action of gravity. The introduction of biochar helps to improve the sedimentation performance of sludge, making it more compact and easier to separate. At the same time, biochar can also adsorb some soluble organic and inorganic matter to further purify water quality.

[0046] The drainage stage is to discharge the treated clean water out of the system. At this time, the adsorption effect of biochar has removed most of the pollutants, which significantly improves the quality of the discharged water. In addition, biochar can also promote the absorption and utilization of nutrients such as nitrogen and phosphorus by microorganisms, thereby reducing the residual amount of these elements in the sewage.

[0047] During the static stage, the system is in a relatively static state, which is conducive to the further growth and reproduction of microorganisms. The presence of biochar provides a stable attachment matrix for microorganisms, which is conducive to the continuous improvement of the abundance of microbial populations. At the same time, the static stage also helps the biochar to fully contact and react with pollutants in the sewage, further improving the efficiency of nitrogen and phosphorus removal.

[0048] In summary, the introduction of biochar enhances the adsorption capacity of sludge and the metabolic activity of microorganisms, which helps to accelerate the removal process of pollutants such as nitrogen and phosphorus; through multiple mechanisms such as adsorption, oxidation and biodegradation, biochar can significantly reduce the concentration of pollutants such as organic matter and heavy metal ions in sewage, and improve the effluent quality; biochar provides rich attachment space and growth environment for microorganisms, which is conducive to the growth and abundance of microbial populations; biochar has good regeneration performance and can be reused, reducing long-term operating costs. At the same time, the introduction of biochar may also reduce the use of chemical agents, further saving costs.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by using biochar, characterized in that: It includes five stages: water intake, aeration, sedimentation, drainage and standing, and also includes: Step 1: During the water inlet stage, the water inlet pump is turned on, and the sewage enters the aerobic granular sludge reactor through the uniform water distributor at the bottom of the reactor. The water inlet flow rate is controlled by the electromagnetic valve and monitored by the flow meter, and a high flow rate is maintained to make the water inflow in the reactor upflow; Step 2: During the aeration phase, after the water is inletted, the water inlet pump is turned off and the blower is turned on to allow air to enter the reactor through the microporous aerator at the bottom of the reactor. The air flow rate is monitored in real time by the rotor flow meter. Step 3: Sedimentation stage: After aeration is completed, the aerator is turned off and the sludge begins to settle; Step 4: During the water discharge phase, open the drain valve to drain water; Step 5: During the static stage, after the clean water and a small amount of sludge flocs on the top of the drain valve are discharged, repeat the operation from step 1.

2. The method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by biochar according to claim 1, characterized in that: The upflow water inflow time inside the reactor is 5 minutes.

3. The method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by biochar according to claim 1, characterized in that: The aeration duration of the aeration stage is 310 min, and the aeration time of the aeration stage is gradually increased to 10 min, 12 min, 15 min and 17 min.

4. The method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by biochar according to claim 1, characterized in that: The sedimentation time in the sludge acclimation stage is 20 minutes, and over time, the sedimentation time in the sludge acclimation stage is gradually reduced to 15 minutes, 10 minutes, 8 minutes and 5 minutes.

5. The method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by biochar according to claim 1, characterized in that: The drainage valve adopts a drainage ratio of 50%, and adopts a drainage ratio of 75% when the inlet COD is lower than 150 mg / l. The drainage flow rate is controlled by an electromagnetic valve, and the drainage time is 5 minutes.

6. The method for enhancing the abundance of microbial populations in sludge and removing nitrogen and phosphorus from sewage by biochar according to claim 1, characterized in that: The standing time of the standing stage is 20 minutes.

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