Sewage treatment method and system for autotrophic denitrification coupled with biological phosphorus removal

Abstract

The present disclosure provides a sewage treatment method and an execution system, comprising: under the conditions of stirring and anaerobic, absorbing and releasing phosphate by anaerobic phosphorus release and internal carbon source conversion reaction in the first sewage, taking the carbon-containing organic matter in the first sewage as a carbon source, to obtain the second sewage; performing aerobic treatment on the second sewage, determining the relative activity of aerobic phosphorus accumulating bacteria and aerobic ammonia-oxidizing bacteria in the second sewage according to the pH value change trend of the second sewage; treating the second sewage by using a multi-stage aeration mode according to the relative activity, adjusting the dissolved oxygen concentration by adjusting the aeration mode of the multi-stage aeration, to occur integrated nitritation-anammox and aerobic phosphorus absorption reaction, to obtain the third sewage; under the conditions of stirring and anaerobic, performing deep phosphorus and nitrogen removal on the third sewage by anaerobic ammonia oxidation reaction, denitrification phosphorus removal reaction and internal carbon source denitrification reaction to obtain the fourth sewage; standing the fourth sewage to separate the sludge and water, and outputting the sewage obtained after the sludge and water separation.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of sewage biological treatment, and particularly relates to a sewage treatment method and system for autotrophic denitrification coupled with biological phosphorus removal. BACKGROUND

[0002] The biological treatment process of sewage is to remove organic matter, nitrogen and phosphorus nutrients in sewage by microorganisms, so as to achieve the purpose of purification. For biological denitrification and phosphorus removal of sewage, the difficulty lies in the distribution of carbon source and the competition of dissolved oxygen in the microbial reaction, especially for low carbon-nitrogen ratio sewage, it is difficult to achieve efficient and stable simultaneous denitrification and phosphorus removal. It is beneficial to improve the activity of bacteria to maintain a high DO concentration (DO≥1.0mg / L) in the aerobic tank for aerobic ammonia-oxidizing bacteria and phosphorus-accumulating bacteria. In addition, anaerobic ammonia-oxidizing bacteria need to maintain a low DO concentration (DO≤0.3mg / L). In addition, the sludge environment for the survival of microorganisms is also in conflict: ammonia-oxidizing bacteria are mostly autotrophic microorganisms, which require a long sludge age; and phosphorus-removing microorganisms need to be controlled at a low sludge age.

[0003] Therefore, it is of great significance to find a more flexible and more balanced denitrification and phosphorus removal process for biological activity in the field of sewage treatment. SUMMARY

[0004] Therefore, in order to solve at least one of the technical problems in the related art and other aspects, the present disclosure provides a sewage treatment method and device.

[0005] In one aspect of the present disclosure, a sewage treatment method is provided, comprising the following steps.

[0006] Step S1: Under the condition of first stirring and anaerobic, the carbon-containing organic matter in the first sewage is absorbed as a carbon source and releases phosphate by anaerobic phosphorus release and internal carbon source conversion reaction, and the second sewage is obtained.

[0007] Step S2: The second sewage is subjected to aerobic treatment, and the relative activity of aerobic phosphorus-accumulating bacteria and aerobic ammonia-oxidizing bacteria in the second sewage is determined according to the pH value change trend of the second sewage.

[0008] Step S3: The second sewage is treated by a multi-stage aeration mode according to the relative activity, and the dissolved oxygen concentration is adjusted by adjusting the multi-stage aeration mode, so that the aerobic phosphorus-accumulating bacteria undergoes aerobic phosphorus uptake reaction and the ammonia-oxidizing bacteria undergoes aerobic ammonia oxidation reaction and anaerobic ammonia oxidation reaction, and part of ammonia nitrogen, total nitrogen and phosphate in the second sewage is removed, and nitrate and nitrite are produced, and the third sewage is obtained.

[0009] Step S4: Deeply removing phosphorus and nitrogen in the third wastewater by anaerobic ammonia oxidation reaction, denitrification phosphorus removal reaction and internal carbon source denitrification reaction under the condition of second stirring and anaerobic, to remove ammonia nitrogen, phosphate, nitrate and nitrite in the third wastewater, and obtain fourth wastewater.

[0010] Step S5: The fourth wastewater is left to separate sludge and water, and the wastewater obtained after sludge and water separation is output.

[0011] According to the embodiment of the present disclosure, the multi-stage aeration mode includes: a first aeration mode, a second aeration mode, and a third aeration mode. The dissolved oxygen concentration in the first aeration mode is 0.8-1.2 mg / L; the dissolved oxygen concentration in the second aeration mode is 0.4-0.7 mg / L; and the dissolved oxygen concentration in the third aeration mode is 0.2-0.3 mg / L.

[0012] According to the embodiment of the present disclosure, in the case that the pH value of the second wastewater is unchanged or increased relative to the first wastewater, it is determined that the activity of aerobic phosphorus accumulating bacteria is greater than that of aerobic ammonia oxidizing bacteria, and the process of multi-stage aeration is: first aeration mode-second aeration mode-third aeration mode.

[0013] According to the embodiment of the present disclosure, in the case that the pH value of the second wastewater is decreased relative to the first wastewater, it is determined that the activity of aerobic phosphorus accumulating bacteria is less than that of aerobic ammonia oxidizing bacteria, and the process of multi-stage aeration is: third aeration mode-second aeration mode-first aeration mode.

[0014] According to the embodiment of the present disclosure, in the case that the oxidation-reduction potential of the first wastewater reaction decreases to-200 to-300 mV, the first stirring and anaerobic treatment is stopped, and the second wastewater is obtained.

[0015] According to the embodiment of the present disclosure, in the case that the ammonia nitrogen concentration in the second wastewater decreases to 20-40 mg / L, the multi-stage aeration mode treatment is stopped, and the third wastewater is obtained.

[0016] According to the embodiment of the present disclosure, in the case that the ammonia nitrogen concentration in the third wastewater decreases to 10-20 mg / L, the second stirring and anaerobic treatment is stopped, and the fourth wastewater is obtained.

[0017] According to the embodiment of the present disclosure, the aeration mode switching of the multi-stage aeration mode is realized by adjusting the aeration amount and the aeration frequency.

[0018] According to the embodiment of the present disclosure, the time of the first stirring and anaerobic treatment is 120-180 min; and the time of the second stirring and anaerobic treatment is 60-120 min.

[0019] In another aspect of the present disclosure, a device for performing the aforementioned wastewater treatment method is provided, comprising a reaction unit, an aeration unit, a detection unit, and a control unit.

[0020] According to an embodiment of the present disclosure, the reaction unit comprises a sequencing batch reactor suitable for accommodating flocculent sludge and microbial packing, and the sequencing batch reactor is suitable for treating the wastewater by microbial action to remove pollutants in the first wastewater, and output the treated wastewater, wherein the pollutants include nitrogen-containing pollutants, phosphorus-containing pollutants, and carbon-containing organic matter. The aeration unit is configured to inject dissolved oxygen into the reaction unit. The detection unit comprises a plurality of detection electrodes arranged in the reaction unit, and is suitable for detecting wastewater parameters in the reaction unit, including ammonia nitrogen concentration, dissolved oxygen concentration, pH value, oxidation-reduction potential, and wastewater liquid level. The control unit is suitable for controlling the water inlet and outlet of the reaction unit and the aeration unit in response to the wastewater parameters, so as to perform the aforementioned wastewater treatment method.

[0021] According to an embodiment of the present disclosure, the concentration of flocculent sludge in the reaction unit is 3-5 g / L; the diameter of the microbial packing in the reaction unit is 1-2 cm, the specific surface area is 300-500 m 2 / m 3 , the packing rate is 20%-25%, and the microbial adhesion amount is 460-550 mg-TS·m -3 .

[0022] According to an embodiment of the present disclosure, the aeration unit comprises an aeration disc, an aeration fan, and a gas flow meter. The aeration disc is arranged at the bottom of the reaction unit and is suitable for injecting dissolved oxygen into the wastewater in the reaction unit. The aeration fan is arranged outside the reaction unit and is in communication with the aeration disc through a pipeline, and is suitable for introducing oxygen into the aeration disc. The gas flow meter is connected to the pipeline and is suitable for detecting the aeration amount and the aeration frequency.

[0023] According to an embodiment of the present disclosure, the detection electrodes of the detection unit comprise an oxidation-reduction electrode, a dissolved oxygen electrode, an ammonia nitrogen electrode, a pH electrode, and a liquid level meter.

[0024] According to an embodiment of the present disclosure, the nitrosation-anaerobic ammonia oxidation, biological phosphorus removal, and short-range denitrification-anaerobic ammonia oxidation are coupled in the same reactor to realize the simultaneous removal of carbon, nitrogen, and phosphorus in the wastewater. In the aeration stage, the wastewater treatment method provided by the present disclosure can flexibly adjust the aeration mode according to the concentrations of organic matter, nitrogen, and phosphorus in the wastewater and the microbial activity, on the one hand, to balance the working state of the denitrification and phosphorus removal microorganisms and improve the removal efficiency of pollutants, and on the other hand, to save the aeration energy consumption and realize high-efficiency and low-carbon operation. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a wastewater treatment flowchart in an embodiment of the present disclosure;

[0026] Figure 2 is a schematic diagram of a wastewater treatment system device in the embodiments of the present disclosure.

[0027] In the above-mentioned drawings, the meanings of the reference signs are as follows:

[0028] 1. Inlet water tank;

[0029] 2. Inlet water pump;

[0030] 3. Sequencing batch reactor;

[0031] 4. Aeration blower;

[0032] 5. Gas flow meter;

[0033] 6. Aeration disc;

[0034] 7. Agitator;

[0035] 8. Liquid level meter;

[0036] 9. Oxidation-reduction electrode;

[0037] 10. Dissolved oxygen electrode;

[0038] 11. Ammonia nitrogen electrode;

[0039] 12. pH electrode;

[0040] 13. Biological filler;

[0041] 14. Sampling port;

[0042] 15. First electrode table;

[0043] 16. Second electrode table;

[0044] 17. Control unit;

[0045] 18. Outlet;

[0046] 19. Outlet valve;

[0047] 20. Outlet water tank. DETAILED DESCRIPTION

[0048] In order to make the purposes, technical solutions and advantages of the present disclosure clearer, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the drawings.

[0049] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges are generally provided as approximations. Unless otherwise stated, the endpoints of the ranges are not limited to the precise values stated. Any value falling within the range is included. The endpoints of the ranges are typically provided to indicate that the range is from and including the lower value and to the higher value. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10. Also, all references to "outer" and "inner" are made with respect to the center of the range.

[0050] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined herein. It should be noted that the use of certain terms or words, such as those listed below, should not be understood to exclude other terms or words from being used in addition to those that are listed.

[0051] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting of the disclosure. As used herein, the terms "comprises", "comprising", "includes", "including" and the like are specifically intended to be open-ended and to mean that other elements can be added.

[0052] In the present disclosure, unless specifically stated and limited otherwise, the terms "mounting", "connected", "connecting", "fixed", "fixedly connected", and the like, should not be construed as being limited to direct and tight connections, but can be understood as being inclusive of a variety of specific connections between two elements, such as mechanical or electrical connections, or communication connections between two elements, unless otherwise explicitly stated and limited. In addition, it can be understood by those skilled in the art that the above terms can be interpreted in the specific meaning in the present disclosure according to the specific circumstances.

[0053] In the description of the present disclosure, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "back", "left", "right", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present disclosure and simplify the description, and therefore should not be construed or implied that the subsystems or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present disclosure.

[0054] Throughout the drawings, the same elements are denoted by the same or similar reference numbers. When it can cause confusion in understanding the present disclosure, conventional structures or configurations will be omitted. In addition, the shape, size, positional relationship of the components in the drawings do not reflect the actual size, ratio and actual positional relationship. In addition, in the present disclosure, any reference symbol located between parentheses should not be construed as limiting the present disclosure.

[0055] Similarly, to simplify the present disclosure and aid understanding of one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present disclosure, various features of the present disclosure are sometimes grouped together in a single embodiment, figure or description thereof. Reference to a term "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. The illustrative appearances of the above described terms in the description are not necessarily all referring to the same embodiment or example. Furthermore, the described particular features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0056] In addition, the terms "first", "second", and the like are used only to describe the purpose and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0057] In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present disclosure.

[0058] In the related art, biological phosphorus removal reaction is to use polyphosphorus bacteria to release phosphorus under anaerobic conditions, and then to absorb excess phosphorus under aerobic or anoxic conditions, so as to remove phosphates in wastewater through sludge discharge. In the biological phosphorus removal reaction, the pH value decreases in the anaerobic process and the pH value increases in the aerobic process. The phosphorus absorption rate of the aerobic phosphorus absorption reaction is improved under the condition of high dissolved oxygen (DO) (DO≥0.5 mg / L).

[0059] In the related art, integrated nitritation-anammox is an autotrophic denitrification process, which grows and reacts with aerobic ammonia-oxidizing bacteria and anaerobic ammonia-oxidizing bacteria in the same reactor by using certain control means, so as to realize collaborative denitrification. This process has the advantages of no need for external carbon source, low aeration energy consumption, and low sludge yield. Aerobic ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) are autotrophic microorganisms, and AnAOB needs nitrite (NO 2-) as substrate. Aerobic ammonia oxidizing bacteria consume alkalinity when nitrosation reaction occurs, and pH value decreases. Although anaerobic ammonia oxidation reaction produces a small amount of alkalinity, pH value shows a significant decreasing trend when integrated nitrosation-anaerobic ammonia oxidation occurs. Integrated nitrosation-anaerobic ammonia oxidation process often adopts low dissolved oxygen (DO≤0.2 mg / L) control, and floc sludge or granular sludge type is often used in the reactor.

[0060] However, the following problems exist in actual operation: first, due to the limitation of low DO condition, if DO supply is insufficient, AOB activity will be inhibited, thereby causing substrate NO 2- to be insufficient; and higher DO concentration will inhibit the activity of AnAOB. Second, organic matter rich in wastewater also has different degrees of inhibition on AOB and AnAOB. At the same time, if phosphorus removal microorganisms are added to the reactor of integrated nitrosation-anaerobic ammonia oxidation process, they cannot work cooperatively with nitrogen removal microorganisms.

[0061] In the denitrification and phosphorus removal reactor, the activity of functional microorganisms is in dynamic change. The aeration strategy and device of traditional integrated nitrosation-anaerobic ammonia oxidation often adopt fixed reaction process (for example, fixed aeration start-stop, reaction time, etc.) and fixed aeration rate, and in the aeration stage, DO adopts a lower range (DO≤0.3 mg / L), which will cause the reduction of treatment efficiency and waste of energy consumption, and cannot coordinate the simultaneous removal needs of carbon, nitrogen and phosphorus. Specifically, the traditional integrated nitrosation-anaerobic ammonia oxidation process has difficulty in solving the problem that denitrification and phosphorus removal microorganisms have different requirements for organic matter and dissolved oxygen when treating wastewater. Insufficient and excessive substrate will inhibit the efficiency of denitrification and phosphorus removal, in addition, the fluctuation of microbial activity and influent water quality will also lead to the reduction of nitrogen and phosphorus simultaneous removal efficiency and aeration efficiency.

[0062] In order to realize the coupling of autotrophic denitrification and biological phosphorus removal process, the sequencing batch reactor needs to be operated in anaerobic, aerobic (anoxic) conditions to provide reaction conditions for polyphosphorus bacteria. Increasing the DO concentration in the aeration stage is beneficial to the improvement of phosphorus absorption reaction rate. In addition, partial denitrification-anaerobic ammonia oxidation, denitrification phosphorus removal and other reactions under anoxic conditions can also achieve the simultaneous removal of nitrate and phosphorus.

[0063] The present disclosure proposes an aeration optimization control strategy based on automatic control, which reduces the energy consumption of treatment while realizing the efficient removal of carbon, nitrogen and phosphorus pollutants. At the same time, by constructing a floc sludge-biofilm composite process, a resilient system suitable for the aforementioned wastewater denitrification and phosphorus removal method, suitable for the growth of ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, denitrifying bacteria and polyphosphorus bacteria is formed.

[0064] In one aspect of the present disclosure, a wastewater treatment method is proposed, comprising the following steps.

[0065] Step S1: Under the condition of first stirring and anaerobic, the carbon-containing organic matter in the first wastewater is absorbed as a carbon source and releases phosphate by anaerobic phosphorus release and internal carbon source conversion reaction, to obtain second wastewater.

[0066] Step S2: The second wastewater is subjected to aerobic treatment, and the relative activity of aerobic phosphorus accumulating bacteria and aerobic ammonia-oxidizing bacteria in the second wastewater is determined according to the pH value change trend of the second wastewater.

[0067] Step S3: The second wastewater is treated by adopting a multi-stage aeration mode according to the relative activity, and the dissolved oxygen concentration is adjusted by adjusting the multi-stage aeration mode, so that the aerobic phosphorus accumulating bacteria undergoes aerobic phosphorus uptake reaction and the ammonia-oxidizing bacteria undergoes aerobic ammonia oxidation reaction and anaerobic ammonia oxidation reaction, thereby cooperatively removing part of ammonia nitrogen, total nitrogen and phosphate in the second wastewater, and generating nitrate and nitrite, to obtain third wastewater.

[0068] Step S4: Under the condition of second stirring and anaerobic, the third wastewater is subjected to advanced phosphorus removal and denitrification by anaerobic ammonia oxidation reaction, denitrification phosphorus removal reaction and internal carbon source denitrification reaction, to remove ammonia nitrogen, phosphate, nitrate and nitrite in the third wastewater, to obtain fourth wastewater.

[0069] Step S5: The fourth wastewater is left to separate the sludge and water, and the wastewater obtained after the sludge and water separation is output.

[0070] According to the embodiments of the present disclosure, the nitritation-anaerobic ammonia oxidation, biological phosphorus removal and the like are coupled in the same sequencing batch reactor, to realize the simultaneous removal of carbon, nitrogen and phosphorus in wastewater. In the aeration stage, the wastewater treatment method proposed by the present disclosure adjusts the aeration mode according to the concentrations of organic matter, nitrogen and phosphorus in the wastewater and the microbial activity, on the one hand, balances the working state of the denitrification and phosphorus removal microorganisms, improves the removal efficiency of pollutants, and on the other hand, saves the aeration energy consumption, and realizes efficient and low-carbon operation.

[0071] According to the embodiments of the present disclosure, in step S1, the organic matter in the influent is converted into internal carbon source by some glycogen bacteria and phosphorus accumulating bacteria and stored in the cell body; at the same time, the phosphorus accumulating bacteria complete the release of phosphate by absorbing the dissolved organic matter in the influent, about 90% of the organic matter in the influent is utilized or converted into internal carbon source, avoiding the inhibition of anaerobic ammonia-oxidizing bacteria. The theoretical reaction time of the anaerobic stage is about 120-180 min, and it is observed that the redox potential in the first wastewater decreases to-200 to-300 mV, and the specific reaction time can be adjusted according to the actual reaction progress.

[0072] According to the embodiment of the present disclosure, the multi-stage aeration mode includes: a first aeration mode, a second aeration mode, and a third aeration mode, wherein the dissolved oxygen concentration in the first aeration mode ranges from 0.8 to 1.2 mg / L; the dissolved oxygen concentration in the second aeration mode ranges from 0.4 to 0.7 mg / L; and the dissolved oxygen concentration in the third aeration mode ranges from 0.2 to 0.3 mg / L.

[0073] According to the embodiment of the present disclosure, by the multi-stage aeration mode, the aeration strategy is optimized, the working order of microorganisms is balanced, and the removal efficiency of pollutants is improved, thereby saving aeration energy consumption.

[0074] According to the embodiment of the present disclosure, in the case that the pH value of the second wastewater is unchanged or increased relative to the first wastewater, it is determined that the activity of the aerobic phosphorus accumulating bacteria is greater than the activity of the ammonia oxidizing bacteria, and the multi-stage aeration process is: the first aeration mode-the second aeration mode-the third aeration mode.

[0075] According to the embodiment of the present disclosure, in the case that the pH value of the second wastewater is decreased relative to the first wastewater, it is determined that the activity of the aerobic phosphorus accumulating bacteria is less than the activity of the ammonia oxidizing bacteria, and the multi-stage aeration process is: the third aeration mode-the second aeration mode-the first aeration mode.

[0076] According to the embodiment of the present disclosure, in step S2, the activity relationship of the microorganisms is determined by actually testing the parameters, and then the aeration stage of step S3 is performed, by adjusting the aeration strategy, the simultaneous occurrence or the alternate occurrence of the nitritation-anammox and the aerobic phosphorus uptake can be controlled. In the case that the pH value of the second wastewater is unchanged or increased relative to the first wastewater, it is determined that the activity of the aerobic phosphorus accumulating bacteria is greater than the activity of the ammonia oxidizing bacteria, and the aeration is started by preferentially adopting the first aeration mode-the second aeration mode-the third aeration mode. The phosphorus accumulating bacteria preferentially perform the phosphorus uptake reaction by using the dissolved oxygen; in the case that the pH value of the second wastewater is decreased relative to the first wastewater, it is determined that the activity of the aerobic phosphorus accumulating bacteria is less than the activity of the aerobic ammonia oxidizing bacteria, and the third aeration mode-the second aeration mode-the first aeration mode is preferentially adopted to occur the integrated nitritation-anammox reaction. In the aeration stage of step S3, the ammonia nitrogen and the phosphate can be removed simultaneously or successively, and a small amount of nitrate is produced.

[0077] According to the embodiment of the present disclosure, in step S3, the integrated nitritation-anammox occurs, the ammonia nitrogen is converted into nitrogen and a small amount of nitrate, and at the same time, the aerobic phosphorus accumulating bacteria perform the aerobic excess phosphorus uptake reaction to absorb the phosphate in the wastewater to synthesize new cells, thereby removing the phosphorus-rich sludge.

[0078] Figure 1 is a wastewater treatment flowchart in the embodiment of the present disclosure.

[0079] In steps S2 and S3, the pH change can be combined with the ammonia nitrogen concentration in the sewage to make a comprehensive judgment. Meanwhile, as shown in FIG. 8, the aeration time of the multi-stage aeration mode can be adjusted according to the real-time single detection of the ammonia nitrogen concentration. Figure 1

[0080] According to an embodiment of the present disclosure, when the oxidation-reduction potential of the first sewage reaction decreases to -200 to -300 mV, the first stirring and anaerobic treatment are stopped, and the second sewage is obtained.

[0081] According to an embodiment of the present disclosure, when the ammonia nitrogen concentration in the second sewage decreases to 20 to 40 mg / L, the multi-stage aeration mode treatment is stopped, and the third sewage is obtained.

[0082] According to an embodiment of the present disclosure, after the aeration stage of step S3 ends, the remaining ammonia nitrogen in the third sewage will be used as a reactant for subsequent anaerobic ammonia oxidation.

[0083] According to an embodiment of the present disclosure, when the ammonia nitrogen concentration in the third sewage decreases to 10 to 20 mg / L, the second stirring and anaerobic treatment are stopped, and the fourth sewage is obtained.

[0084] According to an embodiment of the present disclosure, the aeration mode switching of the multi-stage aeration mode is achieved by adjusting the aeration amount and the aeration frequency.

[0085] According to an embodiment of the present disclosure, the aeration mode switching is achieved by adjusting the aeration amount and the aeration frequency to adjust the aeration air volume. The specific aeration amount and the aeration frequency are adjusted according to the real-time change of the dissolved oxygen concentration. The aeration time is controlled as a termination point by real-time feedback of the ammonia nitrogen electrode 11 or fixed time length.

[0086] According to an embodiment of the present disclosure, in step S4, the short-range denitrifying bacteria can convert the nitrate produced in step S3 into nitrite by using the internal carbon source stored in step S1. The generated nitrite then performs an anaerobic ammonia oxidation reaction with the remaining ammonia nitrogen in the sequencing batch reactor 3, generates nitrogen, and realizes deep denitrification. At the same time, the denitrifying phosphorus accumulating bacteria can also absorb phosphate by using the nitrate, thereby realizing simultaneous removal of nitrogen and phosphorus.

[0087] According to an embodiment of the present disclosure, the time of the first stirring and anaerobic treatment is 120 to 180 min; and the time of the second stirring and anaerobic treatment is 60 to 120 min.

[0088] ​According to the embodiments of the present disclosure, the stirring time of the first sewage and the third sewage is theoretically calculated and conventionally inferred, and in actual application, the stirring time can be adjusted and controlled according to the monitored sewage parameters, for example, the redox potential is adjusted according to the growth and respiration mode of the microorganism, for example, in anaerobic treatment, the redox potential needs to be lower than -200 mV, and the anaerobic treatment time can be controlled according to the real-time change of the redox potential.

[0089] According to the embodiments of the present disclosure, the standing precipitation time in step S5 is preferably 30 min.

[0090] Figure 2 is a schematic diagram of a sewage treatment system device in the embodiments of the present disclosure.

[0091] In another aspect of the present disclosure, a device for performing the aforementioned sewage treatment method is provided, as shown in Figure 2 The device includes a reaction unit, an aeration unit, a detection unit, and a control unit 17.

[0092] According to the embodiments of the present disclosure, the reaction unit includes a sequencing batch reactor 3 suitable for containing floc sludge and microbial filler, and the sequencing batch reactor 3 is suitable for treating sewage by microbial action to remove pollutants in the first sewage, and outputs treated sewage, wherein the pollutants include nitrogen-containing pollutants, phosphorus-containing pollutants, and carbon-containing organic matter. The aeration unit is configured to inject dissolved oxygen into the reaction unit. The detection unit includes a plurality of detection electrodes arranged in the reaction unit, which are suitable for detecting sewage parameters in the reaction unit, including ammonia nitrogen concentration, dissolved oxygen concentration, pH value, redox potential, and sewage liquid level. The control unit is suitable for controlling the water inlet and outlet of the reaction unit and the aeration unit in response to the sewage parameters to perform the above-mentioned sewage treatment method.

[0093] According to the embodiments of the present disclosure, the sequencing batch reactor 3 of the reaction device body highly integrates the sewage treatment process, and does not need complex and large equipment for treatment. The sequencing batch reactor 3 contains floc sludge and biological filler 13, and the microorganism exists in two forms of suspended state and attached state. The autotrophic and anaerobic microorganism, such as anaerobic ammonia oxidation bacteria, grows in an attached state, can be retained and grown in the sequencing batch reactor 3, and is prevented from being inhibited by factors such as organic matter in the influent and high dissolved oxygen generated by aeration. At the same time, the anaerobic ammonia oxidation bacteria can resist the adverse effects of temperature changes. At the same time, the reaction device is based on an automatic control system, and realizes automatic water inlet, aeration, anoxic stirring, and sedimentation and drainage, thereby saving process treatment and labor costs.

[0094] According to the embodiments of the present disclosure, the concentration of the floc sludge in the reaction unit is 3-5 g / L; the diameter of the biological filler 13 in the reaction unit is 1-2 cm, and the specific surface area is 300-500 m 2 / m 3, the filling rate is 20%~25%, and the microbial adhesion amount is 460~550 mg-TS·m -3 .

[0095] According to the embodiment of the present disclosure, the sequencing batch activated sludge reactor 3 in the reaction unit is composed of a flocculent sludge and a biofilm composite system, the sludge age is controlled at 20~25 d, the material of the biofilm filler is polyurethane sponge, the diameter is preferably about 2 cm, the specific surface area is 600 m 2 / m 3 , and the filling rate is 20%. The sludge adhesion amount is related to the dissolved oxygen concentration in the aeration stage. When the microbial adhesion amount on the biofilm is high, the first aeration mode can be used.

[0096] According to the embodiment of the present disclosure, the aeration unit includes an aeration disc 6, an aeration fan 4, and a gas flow meter 5. The aeration disc 6 is arranged at the bottom of the reaction unit and is suitable for injecting dissolved oxygen into the wastewater in the reaction unit. The aeration fan 4 is arranged outside the reaction unit and is in communication with the aeration disc 6 through a pipeline and is suitable for introducing oxygen into the aeration disc 6. The gas flow meter 5 is connected to the pipeline and is suitable for detecting the aeration amount and the aeration frequency.

[0097] According to the embodiment of the present disclosure, the detection electrode of the detection unit includes an oxidation-reduction electrode 9, a dissolved oxygen electrode 10, an ammonia-nitrogen electrode 11, a pH electrode 12, and a liquid level meter 8.

[0098] According to the embodiment of the present disclosure, the detection unit monitors the wastewater parameters in the reaction unit in real time through the detection electrode. The oxidation-reduction electrode 9 is used for detecting the oxidation-reduction state of the reaction unit as a whole. The dissolved oxygen electrode 10 is used for detecting the change of the dissolved oxygen concentration in the wastewater. The ammonia-nitrogen electrode 11 is used for detecting the change of the ammonia-nitrogen concentration in the wastewater. The pH electrode 12 is used for detecting the change of the acid-base in the wastewater. The liquid level meter 8 is used for detecting the wastewater height in the reaction unit. The wastewater parameters detected by the detection electrode are transmitted to the control system, so as to control the wastewater treatment process by controlling the aeration system.

[0099] According to the embodiment of the present disclosure, the control system is a programmable logic controller (PLC).

[0100] In some specific embodiments, in step S1, the wastewater is pumped into the SBR reactor 3 from the water inlet tank 1 by the water inlet pump 2. When the liquid level meter 8 detects that the water amount reaches the set value, the PLC control system immediately controls the water inlet pump 2 to stop and the stirring paddle 7 to start, and the reaction enters the anaerobic stage.

[0101] In some specific embodiments, in step S2 and step S3, the aeration fan is automatically turned on, and the PLC control system adjusts the aeration fan frequency according to the organic matter, nitrogen, phosphorus concentration and microbial activity in the sewage to form a multi-mode aeration mode. In this stage, nitrosation-anaerobic ammonia oxidation and aerobic phosphorus absorption can occur simultaneously or alternately, and accordingly, ammonia nitrogen and phosphate can be removed simultaneously or successively, and a certain concentration of nitrate is produced. The aeration stop can be controlled by a time relay or an online ammonia nitrogen electrode. At the end of the reaction, the residual ammonia nitrogen concentration is 20-40 mg / L.

[0102] In some specific embodiments, after step S3 is completed, the aeration fan is turned off, the reaction enters an anoxic stirring stage, and deep denitrification is achieved. At the same time, denitrifying phosphorus-accumulating bacteria can also absorb phosphate using nitrate, thereby achieving simultaneous removal of nitrogen and phosphorus. The reaction time is controlled by time or ammonia nitrogen electrode 11, and is 60-120 min.

[0103] In some specific embodiments, after the anoxic stirring stage of step S4 is completed, the stirring paddle 7 is turned off, the reaction enters a standing and sedimentation stage, and the standing and sedimentation time is 30 min. After the standing and sedimentation is completed, the effluent valve is automatically opened, the reaction enters a drainage stage, and the supernatant automatically flows into the effluent tank 20. The drainage volume is controlled by the liquid level meter 8 and the PLC control system, and the single drainage volume is about 5 L. The drainage time is 2-5 min.

[0104] In some specific embodiments, after the drainage in step S5 is completed, the effluent valve is closed, and the reaction enters the next cycle.

[0105] It should be noted that the embodiments described are only some of the embodiments of the present disclosure, not all the embodiments. Based on the embodiments in the present disclosure, other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present disclosure.

[0106] Embodiments

[0107] In this embodiment, the pig farm anaerobic digestion liquid is used as the treated sewage, which contains a high concentration of nitrogen and phosphorus, a low carbon-nitrogen ratio, and a large fluctuation in pollutant concentration. The specific water quality indexes are shown in Table 1 below:

[0108] Table 1:

[0109]

[0110] During the experiment, the specific operation parameters of the reactor are as follows:

[0111] The integrated SBR reactor has an effective volume of 20 L, a floc sludge concentration of 3-5 g / L, a biological filler filling rate of 20%, and a microbial attachment amount of 460-550 mg-TS·m-3 The metal bracket is fixed in the reactor.

[0112] Influent stage: the influent pump is opened, and single influent is 5 L, and the ammonia nitrogen concentration of the sewage in the reactor is 100-150 mg / L.

[0113] Anaerobic stage: the influent pump is closed, the stirring paddle is opened, the rotating speed is 120 r / min, DO < 0.02 mg / L, and the reaction time is 120-180 min.

[0114] Aeration stage:

[0115] The control group ① is a single aeration mode, and the DO concentration in the fixed aeration stage is 0.2-0.3 mg / L.

[0116] The experimental group ② is a multi-stage aeration mode, and the third aeration mode is used in the aerobic aeration reaction, the DO concentration is set to 0.2-0.3 mg / L, then the aeration fan frequency is increased, and the DO concentration in the reactor is controlled to be 0.4-0.7 and 0.8-1.2 mg / L.

[0117] The experimental group ③ is a multi-stage aeration mode, and the first aeration mode is used in the initial stage of aerobic aeration, the aeration fan frequency is increased, and the DO concentration in the reactor is controlled to be 0.8-1.2 mg / L, when the ammonia nitrogen concentration in the reactor is reduced to 60 mg / L, the aeration fan frequency is reduced, the DO in the reactor is controlled to be 0.4-0.7 mg / L, then it is further reduced to 0.2-0.3 mg / L, and the residual ammonia nitrogen concentration is 20-40 mg / L at the end of the reaction.

[0118] Anoxic stage: the aeration fan is closed, DO < 0.02 mg / L, the reaction time is 120-180 min, and the residual ammonia nitrogen concentration is 10-20 mg / L.

[0119] Precipitation stage: the stirring paddle is closed, and the precipitation time is 30 min.

[0120] Drainage stage: the effluent valve is opened, and single drainage is 5 L.

[0121] In the control group ① in the conventional single aeration mode, the removal rates of COD, TN, PO4 3- -P are 82%, 90% and 45% respectively; in the experimental group ② (high aeration amount in the later period), the removal rates of COD, TN, PO4 3- -P reach 83%, 94% and 65.2% respectively; in the experimental group ③ (high aeration amount in the early period), the removal rates of COD, TN, PO4 3-The P removal rates reached 86%, 96%, and 60% respectively, realizing efficient simultaneous removal of carbon, nitrogen and phosphorus in the anaerobic digestion liquid of the pig farm. Meanwhile, it is found in the examples that the hydraulic retention time of the experimental groups ② and ③ is reduced by 20%-30% compared with the control group ①.

[0122] The above-described specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above-described specific embodiments are merely specific embodiments of the present disclosure and are not used to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A wastewater treatment method combining autotrophic nitrogen removal with biological phosphorus removal, comprising: Under the first stirring and anaerobic conditions, the carbon-containing organic matter in the first wastewater is absorbed as a carbon source and phosphate is released through anaerobic phosphorus release and internal carbon source conversion reaction, resulting in the second wastewater. The second wastewater was subjected to aerobic treatment, and the relative activities of aerobic polyphosphate-accumulating bacteria and aerobic ammonia-oxidizing bacteria in the second wastewater were determined based on the pH value change trend of the second wastewater. The second wastewater is treated using a multi-stage aeration mode based on the relative activity. The dissolved oxygen concentration is adjusted by changing the multi-stage aeration mode so that the aerobic polyphosphate-accumulating bacteria can undergo aerobic phosphorus uptake and the ammonia-oxidizing bacteria can undergo aerobic and anaerobic ammonia oxidation reactions. This synergistically removes some ammonia nitrogen, total nitrogen, and phosphate from the second wastewater, while simultaneously producing nitrate and nitrite, resulting in the third wastewater. Under the conditions of second stirring and anaerobic conditions, the third wastewater is subjected to deep phosphorus and nitrogen removal through anaerobic ammonia oxidation reaction, denitrification phosphorus removal reaction and internal carbon source denitrification reaction, so as to remove ammonia nitrogen, phosphate, nitrate and nitrite from the third wastewater to obtain the fourth wastewater; The fourth wastewater is allowed to stand to separate the mud and water, and the wastewater obtained after mud and water separation is output. The multi-stage aeration mode includes: a first aeration mode, a second aeration mode, and a third aeration mode, wherein, In the first aeration mode, the dissolved oxygen concentration ranges from 0.8 to 1.2 mg / L; In the second aeration mode, the dissolved oxygen concentration ranges from 0.4 to 0.7 mg / L; The dissolved oxygen concentration in the third aeration mode ranges from 0.2 to 0.3 mg / L; When the pH value of the second wastewater remains unchanged or increases relative to the first wastewater, it is determined that the activity of the aerobic polyphosphate-accumulating bacteria is greater than the activity of the aerobic ammonia-oxidizing bacteria, and the multi-stage aeration process is: first aeration mode - second aeration mode - third aeration mode. When the pH value of the second wastewater is lower than that of the first wastewater, it is determined that the activity of the aerobic polyphosphate-accumulating bacteria is less than that of the aerobic ammonia-oxidizing bacteria. The multi-stage aeration process is: third aeration mode - second aeration mode - first aeration mode.

2. The wastewater treatment method according to claim 1, wherein, When the redox potential of the first wastewater reaction drops to -200 to -300 mV, the first stirring and anaerobic treatment are stopped to obtain the second wastewater; When the ammonia nitrogen concentration in the second wastewater drops to 20-40 mg / L, the multi-stage aeration mode treatment is stopped to obtain the third wastewater. When the ammonia nitrogen concentration in the third wastewater drops to 10-20 mg / L, the second stirring and anaerobic treatment is stopped to obtain the fourth wastewater.

3. The wastewater treatment method according to claim 1, wherein, The switching of the aeration mode in the multi-segment aeration mode is achieved by adjusting the aeration volume and aeration frequency.

4. The wastewater treatment method according to claim 1, wherein, The duration of the first stirring and anaerobic treatment is 120–180 min; The second stirring and anaerobic treatment takes 60–120 minutes.

5. A wastewater treatment system, comprising: The reaction unit includes a sequencing batch reactor (3) suitable for containing flocculent sludge and microbial packing material. The sequencing batch reactor (3) is suitable for treating wastewater by microbial action to remove pollutants from the first wastewater and output treated wastewater, wherein the pollutants include nitrogen-containing pollutants, phosphorus-containing pollutants and carbon-containing organic matter. An aeration unit is configured to inject dissolved oxygen into the reaction unit; The detection unit includes multiple detection electrodes disposed within the reaction unit, suitable for detecting wastewater parameters within the reaction unit, including ammonia nitrogen concentration, dissolved oxygen concentration, pH value, oxidation-reduction potential, and wastewater level. The control unit (17) is adapted to control the influent and effluent of the reaction unit and the aeration unit in response to the wastewater parameters, so as to perform the wastewater treatment method as described in any one of claims 1 to 4.

6. The system according to claim 5, wherein, The concentration of flocculent sludge in the reaction unit is 3–5 g / L; The diameter of the microbial packing material in the reaction unit is 1–2 cm, and the specific surface area is 300–500 m². 2 / m 3 The filling rate is 20%–25%, and the amount of microbial attachment is 460–550 mg-TS·m -3 .

7. The system according to claim 5, wherein, The aeration unit includes: An aeration disc (6) is installed at the bottom of the reaction unit and is suitable for injecting dissolved oxygen into the wastewater in the reaction unit. An aeration blower (4) is located outside the reaction unit and is connected to the aeration disc (6) via a pipe. It is suitable for introducing oxygen into the aeration disc (6). A gas flow meter (5) is connected to the pipeline and is suitable for detecting aeration volume and aeration frequency.

8. The system according to claim 5, wherein, The detection electrodes of the detection unit include: a redox electrode (9), a dissolved oxygen electrode (10), an ammonia nitrogen electrode (11), a pH electrode (12), and a level gauge (8).

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