A micro-oxygen induced partial short-range nitrification and denitrification water treatment system and method

Abstract

The invention discloses a micro-oxygen induced partial short-range nitrification and denitrification water treatment system and method. The system comprises: a circulating flow structure micro-oxygen pool is divided into a nitrification zone and a denitrification zone, and the effective volume ratio of the nitrification zone to the denitrification zone is 1-4:1; a water outlet is arranged at the end of the circulating flow structure micro-oxygen pool, and the water outlet is connected to an aerobic pool and a sedimentation pool in sequence; a water inlet and a sludge return point are arranged at the same point on one side of the rear of the circulating flow structure micro-oxygen pool, and the positions of the two are located at the front end of the denitrification zone and the end of the nitrification zone in the circulating flow structure micro-oxygen pool according to the water flow direction; the water inlet is connected to a sewage inlet pipe; a micro-aeration device is arranged in the nitrification zone of the circulating flow structure micro-oxygen pool, and the dissolved oxygen in the nitrification zone can be maintained below 1.0 mg / L through the micro-aeration device; a stirrer and a flow pusher are arranged in the denitrification zone of the circulating flow structure micro-oxygen pool, and the inlet water, return sludge and nitrification mixed liquid can be fully mixed; the sedimentation tank is connected to the sludge return point of the circulating flow structure micro-oxygen pool through a sludge return pipe.

Description

Technical Field

[0001] The invention relates to the field of water treatment, and in particular to a micro-oxygen induced partial short-range nitrification and denitrification water treatment system and method. Background Art

[0002] At present, in the biological treatment process of municipal sewage, it is a common problem to meet the total nitrogen standard. In addition to design parameters and operational factors, the lack of organic carbon source for denitrification in the anoxic section is a major reason. The concentration of various pollutants in municipal sewage is low, and the water volume is large. The input of external carbon source will greatly increase the operating cost of the sewage treatment plant. Based on this, changing the traditional biological treatment process is a promising direction.

[0003] Compared with the traditional full-process nitrification and denitrification process, the short-term nitrification and denitrification process has a lower demand for organic carbon sources, less oxygen demand and less sludge production. However, it is difficult to achieve short-term nitrification and denitrification of municipal sewage with low ammonia nitrogen concentration. The reason is that ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) are in a symbiotic relationship. At the same time, there are almost no factors that inhibit NOB in municipal sewage, such as water temperature above 25°C, free ammonia inhibition (under high ammonia nitrogen concentration or high pH value), etc. Therefore, how to achieve partial short-term nitrification of municipal sewage with low ammonia nitrogen concentration at room temperature is a challenging problem.

[0004] Anoxic / aerobic (A / O) denitrification technology: Its denitrification process is to return the nitrified liquid in the aerobic zone to the pre-denitrification zone, and use the organic carbon source (BOD) in the influent to carry out denitrification to complete denitrification. Its characteristic is that excessive aeration is carried out in the aerobic zone to completely nitrify the ammonia nitrogen into nitrate nitrogen, and a part of it is returned for denitrification at the end, and the rest is used as effluent to enter the secondary sedimentation tank for mud and water separation. Although this technology can theoretically remove 75% of nitrate nitrogen (taking a typical internal reflux ratio of 300% as an example), it will cause several problems: ① Excessive aeration causes the internal reflux liquid to carry a certain amount of dissolved oxygen (DO). In the anoxic denitrification zone, since denitrifying bacteria preferentially use high-energy oxygen (O2>NO3 - ), thus affecting the effective denitrification time and resulting in unsatisfactory denitrification effect; ② The absolute partitioning of anoxic and aerobic conditions means that the entire nitrification-denitrification process can only be achieved through reflux, which results in at least a part of the nitrate nitrogen being unable to be removed by denitrification; ③ Excessive aeration in the aerobic zone leads to an increase in energy consumption per unit of sewage, pushing up operating costs and wasting energy.

[0005] SBR technology with denitrification function: Similar to A / O denitrification technology, it converts the anoxic and aerobic spatial partitions in A / O denitrification technology into time intervals in SBR, and converts the internal reflux ratio in A / O denitrification technology into the retention ratio in SBR (retention ratio = 1-drainage ratio). That is, SBR technology completes the nitrification process of ammonia nitrogen during the aeration time, and in the next cycle of water inlet stirring stage after drainage, it uses the nitrate nitrogen in the remaining sewage and the organic carbon source in the influent to carry out denitrification. In addition to several shortcomings of A / O denitrification technology, SBR technology with denitrification function is an intermittent process, the equipment is frequently started, and operation and maintenance are difficult.

[0006] SHARON short-range nitrification-denitrification technology: In the whole nitrification (NH4+→NO2-→NO3-)-denitrification (NO3-→NO2-→N2) process, it can be seen that NO2-→NO3- and NO3-→NO2- are two "multi-paths". Based on this principle, DELFT University in the Netherlands proposed and developed SHARON technology, namely Single reactor High activity Ammonia Removal Over Nitrite, which is a single reactor high activity deammoniation based on nitrite. This technology is mainly used to treat high ammonia nitrogen wastewater, such as sludge digestion supernatant, pressure leachate, etc. By setting aeration and anoxic time periods in a continuous flow complete mixing reactor, maintaining a water temperature above 30°C, using higher temperatures and high concentrations of ammonia nitrogen (free ammonia) to inhibit and eliminate nitrite oxidizing bacteria (NOB), thereby enriching ammonia oxidizing bacteria and making short-term nitrification dominant. During the anoxic period, an organic carbon source is added for nitrite-based denitrification, ultimately forming a short-term nitrification-denitrification process. Compared with the full nitrification-denitrification process, SHARON technology has the advantages of saving aeration and organic carbon sources, and low sludge production. However, this technology uses free ammonia formed by high temperature and high ammonia nitrogen to inhibit the growth of NOB, so it is only suitable for high-temperature, high-ammonia nitrogen type two-high wastewater, and its application range is greatly limited. It is not suitable for normal temperature, low ammonia nitrogen municipal sewage treatment.

[0007] In view of this, the present invention is proposed. Summary of the invention

[0008] The purpose of the present invention is to provide a micro-aerobic induced partial short-range nitrification and denitrification water treatment system and method, which can achieve micro-aerobic induced partial short-range nitrification and denitrification water treatment at normal temperature and low ammonia nitrogen municipal sewage, thereby solving the above-mentioned technical problems existing in the prior art.

[0009] The objective of the present invention is achieved through the following technical solutions:

[0010] A micro-aerobic induced partial short-range nitrification and denitrification water treatment system, comprising:

[0011] Circulating flow structure micro-aerobic pool, aerobic pool and sedimentation tank; among them,

[0012] The circulating flow structure micro-aerobic pool is divided into a nitrification zone and a denitrification zone, and the effective volume ratio of the nitrification zone to the denitrification zone is 1 to 4:1;

[0013] A water outlet is arranged at the end of the circulating flow structure micro-aerobic pool, and the water outlet is connected to the aerobic pool and the sedimentation pool in sequence through pipelines;

[0014] A water inlet point and a sludge return point are arranged at the same point on one side of the rear part of the circulating flow structure micro-aerobic pool, and the positions of the water inlet point and the sludge return point are located at the front end of the denitrification zone and the end of the nitrification zone in the circulating flow structure micro-aerobic pool according to the water flow direction;

[0015] The water inlet point is connected to the sewage inlet pipe;

[0016] A micro-aeration device is provided in the nitrification zone in the circulating flow structure micro-aeration pool, and the dissolved oxygen in the nitrification zone can be maintained below 1.0 mg / L by the micro-aeration device;

[0017] The denitrification zone in the circulating flow structure micro-aerobic pool is provided with an agitator and a flow pusher, which can fully mix the influent, the return sludge and the nitrification mixed liquid;

[0018] The sedimentation tank is connected back to the sludge return point of the circulating flow structure micro-aerobic tank through a sludge return pipe;

[0019] A water outlet and a residual sludge outlet are respectively provided at the end of the sedimentation tank.

[0020] A micro-aerobic induction partial short-range nitrification and denitrification water treatment method, using the system of the present invention, comprises the following steps:

[0021] Sewage with an average water temperature of 18°C ​​enters the circulating flow structure micro-aeration pool of the system through the water inlet point, and is aerated through the micro-aeration device in the nitrification zone of the circulating flow structure micro-aeration pool to maintain the dissolved oxygen below 1.0 mg / L, and the first nitrification is performed to convert ammonia nitrogen into nitrite and nitrate;

[0022] The influent, the return sludge and the nitrification mixed solution are mixed by the agitator and the flow promoter in the denitrification zone in the micro-aerobic tank of the circulating flow structure;

[0023] The sum of nitrite nitrogen and nitrate nitrogen in the effluent of the circulating flow structure microaerobic pool is less than 3.0 mg / L, and the ammonia nitrogen is 5.0-10.0 mg / L. The effluent enters the aerobic pool to perform deep nitrification on the remaining ammonia nitrogen as a second nitrification, and the dissolved oxygen concentration in the aerobic pool is maintained above 1.0 mg / L;

[0024] The sewage enters the sedimentation tank for mud-water separation, and part of the sludge is returned to the circulating flow structure micro-aerobic tank through the sludge return pipe. The effluent of the sedimentation tank enters the next treatment link, and the remaining sludge enters the sludge treatment link.

[0025] Compared with the prior art, the micro-aerobic induction partial short-range nitrification and denitrification water treatment system and method provided by the present invention has the following beneficial effects:

[0026] By adopting a micro-aerobic pool with a specific structure of circulating flow structure, a nitrification zone and a denitrification zone with a specific effective volume ratio are set in it. When it is applied to actual municipal sewage, only low-intensity aeration can be maintained in the nitrification zone to induce partial short-range nitrification (part of the ammonia nitrogen is converted into nitrite nitrogen), thereby saving a part of the organic carbon source in the denitrification process and making the total nitrogen meet the standard. A small section of aerobic pool is connected to the back end to convert the remaining ammonia nitrogen into nitrate nitrogen, so that the ammonia nitrogen meets the standard. This two-stage nitrification technology can save part of the aeration volume and avoid aerobic consumption of organic carbon sources; at the same time, the micro-aerobic environment induces partial short-range nitrification-denitrification, solving the problem of insufficient carbon source in the municipal (domestic) sewage treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 1 A schematic diagram of the structure of a micro-aerobic induced partial short-range nitrification and denitrification water treatment system provided in an embodiment of the present invention.

[0029] In the figure: 1-circulating flow structure micro-aerobic tank; 11-nitrification zone; 12-denitrification zone; 2-aerobic tank; 3-sedimentation tank; 4-water inlet pipe; 5-sludge return pipe; A-water inlet point; B-sludge return point; C-water outlet point; D-water outlet; E-residual sludge outlet. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0031] First, the terms that may be used in this article are explained as follows:

[0032] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0033] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0034] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0035] Unless otherwise specified or limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this article can be understood according to specific circumstances.

[0036] When concentration, temperature, pressure, size or other parameters are expressed in the form of a numerical range, the numerical range should be understood to specifically disclose all ranges formed by the pairing of any upper limit, lower limit, and preferred value in the numerical range, regardless of whether the range is explicitly stated; for example, if a numerical range of "2 to 8" is stated, the numerical range should be interpreted as including ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise specified, the numerical ranges stated herein include both their end values ​​and all integers and fractions within the numerical range.

[0037] The orientation or position relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience and simplification of description, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of this document.

[0038] The micro-aerobic induced partial short-range nitrification and denitrification water treatment system provided by the present invention is described in detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professional and technical personnel in the field. If no specific conditions are specified in the embodiments of the present invention, the conventional conditions in the field or the conditions recommended by the manufacturer are followed. The reagents or instruments used in the embodiments of the present invention, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0039] like Figure 1 As shown, an embodiment of the present invention provides a micro-aerobic induction partial short-range nitrification and denitrification water treatment system, comprising:

[0040] Circulating flow structure micro-aerobic pool, aerobic pool and sedimentation tank; among them,

[0041] The circulating flow structure micro-aerobic pool is divided into a nitrification zone and a denitrification zone, and the effective volume ratio of the nitrification zone to the denitrification zone is 1 to 4:1;

[0042] A water outlet is arranged at the end of the circulating flow structure micro-aerobic pool, and the water outlet is connected to the aerobic pool and the sedimentation pool in sequence through pipelines;

[0043] A water inlet point and a sludge return point are arranged at the same point on one side of the rear part of the circulating flow structure micro-aerobic pool, and the positions of the water inlet point and the sludge return point are located at the front end of the denitrification zone and the end of the nitrification zone in the circulating flow structure micro-aerobic pool according to the water flow direction;

[0044] The water inlet point is connected to the sewage inlet pipe;

[0045] A micro-aeration device is provided in the nitrification zone in the circulating flow structure micro-aeration pool, and the dissolved oxygen in the nitrification zone can be maintained below 1.0 mg / L by the micro-aeration device;

[0046] The denitrification zone in the circulating flow structure micro-aerobic pool is provided with an agitator and a flow pusher, which can fully mix the influent, the return sludge and the nitrification mixed liquid;

[0047] The sedimentation tank is connected back to the sludge return point of the micro-aerobic tank of the circulating flow structure through a sludge return pipe.

[0048] Preferably, in the above system, the hydraulic retention time of the microaerobic pool is 6 to 12 hours; the hydraulic retention time of the aerobic pool is 1 to 3 hours.

[0049] Preferably, in the above system, the circulation reflux ratio of the nitrification mixed solution in the micro-aerobic pool is 3 to 5 times the water intake.

[0050] The embodiment of the present invention also provides a method for treating water by micro-aerobic induction of partial short-range nitrification and denitrification, which uses the above system and includes the following steps:

[0051] Sewage with an average water temperature of 18°C ​​enters the circulating flow structure micro-aeration pool of the system through the water inlet point, and is aerated through the micro-aeration device in the nitrification zone of the circulating flow structure micro-aeration pool to maintain the dissolved oxygen below 1.0 mg / L, and the first nitrification is performed to convert ammonia nitrogen into nitrite and nitrate;

[0052] The influent, the return sludge and the nitrification mixed solution are mixed by the agitator and the flow promoter in the denitrification zone in the micro-aerobic tank of the circulating flow structure;

[0053] The sum of nitrite nitrogen and nitrate nitrogen in the effluent of the circulating flow structure microaerobic pool is less than 3.0 mg / L, and the ammonia nitrogen is 5.0-10.0 mg / L. The effluent enters the aerobic pool to perform deep nitrification on the remaining ammonia nitrogen as a second nitrification, and the dissolved oxygen concentration in the aerobic pool is maintained above 1.0 mg / L;

[0054] The sewage enters the sedimentation tank for mud-water separation, and part of the sludge is returned to the circulating flow structure micro-aerobic tank through the sludge return pipe. The effluent of the sedimentation tank enters the next treatment link, and the remaining sludge enters the sludge treatment link.

[0055] Preferably, in the above method, the circulation reflux ratio of the nitration mixture is 3 to 5 times the water intake.

[0056] From the above, it can be seen that the system and method of the embodiment of the present invention, by adopting a micro-aerobic pool with a specific structure of a circulating flow structure, sets a nitrification zone and a denitrification zone with a specific effective volume ratio therein. When applied to actual municipal sewage, it can induce the formation of partial short-range nitrification (part of the ammonia nitrogen is converted into nitrite nitrogen) by maintaining only low-intensity aeration in the nitrification zone, thereby saving a part of the organic carbon source in the denitrification process and making the total nitrogen meet the standard. A small section of aerobic pool is connected to the back end to convert the remaining ammonia nitrogen into nitrate nitrogen, so that the ammonia nitrogen meets the standard. This two-stage nitrification technology can save part of the aeration volume while avoiding aerobic consumption of organic carbon sources; at the same time, the micro-aerobic environment induces the formation of partial short-range nitrification-denitrification, solving the problem of insufficient carbon source in the process of municipal (domestic) sewage treatment.

[0057] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the micro-aerobic induced partial short-range nitrification and denitrification water treatment system provided by the embodiment of the present invention is described in detail with reference to specific embodiments below.

[0058] Example 1

[0059] like Figure 1 As shown, the embodiment of the present invention provides a micro-aerobic induction partial short-range nitrification and denitrification water treatment system, which can treat municipal (domestic) sewage with an average water temperature above 18°C. The system includes:

[0060] (1) In the circulating flow structure micro-aerobic pool 1, there is a nitrification zone 12 (i.e. Figure 1 The non-dashed area in the figure) and the denitrification zone 11 (i.e. Figure 1 The dotted area in the figure), the ratio of the effective volume of the nitrification zone 12 to the denitrification zone 11 is 1 to 4:1, preferably 2:1, the water inlet point A and the sludge return point B of the circulating flow structure micro-aerobic pool 1 are the same point (it can also be the water inlet cross section or the sludge return cross section), according to the water flow direction, the water inlet point A and the sludge return point B are at the front end of the denitrification zone 11, the end of the nitrification zone 12, and after the end water outlet point C of the circulating flow structure micro-aerobic pool 1, and the water inlet point A is connected to the water inlet pipe 4.

[0061] (2) A small amount of aeration is carried out in the nitrification zone 12, which occupies two-thirds of the effective volume of the circulating flow structure micro-aerobic pool 1, to maintain the dissolved oxygen (DO) below 1.0 mg / L, with a typical value of 0.2-0.5 mg / L, so that ammonia nitrogen is converted into nitrite and nitrate (first nitrification); an agitator and a flow promoter are set in the denitrification zone 11 to fully mix the influent, return sludge and nitrification mixed solution, and the circulating reflux ratio of the nitrification mixed solution is 3-5 times the influent volume (300-500% reflux ratio).

[0062] (3) The sum of nitrite nitrogen and nitrate nitrogen in the effluent of the circulating flow structure microaerobic pool 1 is less than 3.0 mg / L, and the ammonia nitrogen is between 5.0 and 10.0 mg / L. Then it enters the aerobic pool 2 for deep nitrification (second nitrification) of the remaining ammonia nitrogen, maintaining the dissolved oxygen concentration above 1.0 mg / L to ensure that the ammonia nitrogen concentration in the effluent of the aerobic pool 2 is lower than the discharge standard.

[0063] (4) Finally, mud and water are separated in the sedimentation tank 3. Part of the sludge is returned to the circulating flow structure micro-aerobic tank 1 through the sludge return pipe 5 and the sludge return point. The remaining sludge discharged from the sedimentation tank 3 enters the sludge treatment link through the remaining sludge outlet E, and the effluent enters the next treatment link through the outlet D.

[0064] In the above system, the residence time in the microaerobic zone is 6 to 12 hours, and the residence time in the aerobic zone is 1 to 3 hours.

[0065] The system of the present invention makes full use of the certain differences in the biological characteristics of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB), that is, in terms of affinity for dissolved oxygen, the oxygen affinity of AOB is higher than that of NOB. Based on this physiological difference, when the dissolved oxygen in the water is controlled at a lower level, oxygen molecules are preferentially used by AOB. When applied to actual municipal sewage, only low-intensity aeration can be maintained to induce partial short-range nitrification (part of the ammonia nitrogen is converted into nitrite nitrogen), thereby saving a part of the organic carbon source in the denitrification process and making the total nitrogen meet the standard. A small section of aerobic pool is connected to the back end to convert the remaining ammonia nitrogen into nitrate nitrogen, so that the ammonia nitrogen meets the standard. This two-stage nitrification technology can save part of the aeration volume while avoiding aerobic consumption of organic carbon sources; at the same time, the micro-aerobic environment induces partial short-range nitrification-denitrification, solving the problem of insufficient carbon source in the municipal (domestic) sewage treatment process.

[0066] The system of the present invention maintains a low dissolved oxygen concentration (0.2-1.0 mg / L) in the micro-aerobic pool with a circulating flow structure, and maintains the ammonia nitrogen concentration of the micro-aerobic pool effluent between 5.0-10.0 mg / L, thereby inducing partial short-range nitrification and further forming a partial short-range nitrification-denitrification denitrification effect. The former utilizes the biological characteristics that ammonia oxidizing bacteria (AOB) have a stronger affinity for oxygen than nitrite oxidizing bacteria (NOB), making them superior to NOB in a limited dissolved oxygen environment, thereby forming partial short-range nitrification; the latter maintains a certain concentration of ammonia nitrogen in the effluent, that is, maintains the ammonia nitrogen concentration of the entire micro-aerobic pool above 5.0 mg / L, and can utilize a small amount of free ammonia (NH3) in the water at this concentration to synergistically inhibit nitrite oxidizing bacteria, thereby better achieving the purpose of partial short-range nitrification.

[0067] The system and method of the present invention have at least the following beneficial effects, including:

[0068] (1) Short residence time: The residence time HRT of the circulating flow structure micro-aerobic pool + aerobic pool in the system of the present invention is 7 to 10 hours, which can make the four major pollution indicators of ammonia nitrogen, total nitrogen, COD, and BOD5 lower than the Class A standard in the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" GB18918-2002.

[0069] (2) Saving aeration volume: Under the condition of the same hydraulic retention time, the system of the present invention can make the four major pollution indicators of ammonia nitrogen, total nitrogen, COD and BOD5 lower than the Class A standard in the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" GB18918-2002, and save more than 10% of aeration volume.

[0070] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for treating water by micro-aerobic induction of partial short-range nitrification and denitrification, characterized in that: The following micro-oxygen induced partial short-range nitrification and denitrification water treatment system is adopted, including: a circulating flow structure micro-oxygen tank, an aerobic tank and a sedimentation tank; among which, The circulating flow structure micro-aerobic pool is divided into a nitrification zone and a denitrification zone, and the effective volume ratio of the nitrification zone to the denitrification zone is 1 to 4:1; A water outlet is arranged at the end of the circulating flow structure micro-aerobic pool, and the water outlet is connected to the aerobic pool and the sedimentation pool in sequence through pipelines; A water inlet point and a sludge return point are arranged at the same point on one side of the rear part of the circulating flow structure micro-aerobic pool, and the positions of the water inlet point and the sludge return point are located at the front end of the denitrification zone and the end of the nitrification zone in the circulating flow structure micro-aerobic pool according to the water flow direction; The water inlet point is connected to the sewage inlet pipe; A micro-aeration device is provided in the nitrification zone in the circulating flow structure micro-aeration pool, and the dissolved oxygen in the nitrification zone can be maintained below 1.0 mg / L by the micro-aeration device; The denitrification zone in the circulating flow structure micro-aerobic pool is provided with an agitator and a flow pusher, which can fully mix the influent, the return sludge and the nitrification mixed liquid; The sedimentation tank is connected back to the sludge return point of the circulating flow structure micro-aerobic tank through a sludge return pipe; The end of the sedimentation tank is respectively provided with a water outlet and a residual sludge outlet; The method comprises the following steps: Sewage with an average water temperature of 18°C ​​enters the circulating flow structure micro-aeration pool of the system through the water inlet point, and is aerated through the micro-aeration device in the nitrification zone of the circulating flow structure micro-aeration pool to maintain the dissolved oxygen below 1.0 mg / L, and the first nitrification is performed to convert ammonia nitrogen into nitrite and nitrate; The influent, the return sludge and the nitrification mixed solution are mixed by the agitator and the flow promoter in the denitrification zone in the micro-aerobic tank of the circulating flow structure; The sum of nitrite nitrogen and nitrate nitrogen in the effluent of the circulating flow structure microaerobic pool is less than 3.0 mg / L, and the ammonia nitrogen is 5.0-10.0 mg / L. The effluent enters the aerobic pool to perform deep nitrification on the remaining ammonia nitrogen as a second nitrification, and the dissolved oxygen concentration in the aerobic pool is maintained above 1.0 mg / L; The sewage enters the sedimentation tank for mud-water separation, and part of the sludge is returned to the circulating flow structure micro-aerobic tank through the sludge return pipe. The effluent of the sedimentation tank enters the next treatment link, and the remaining sludge enters the sludge treatment link.

2. The micro-aerobic induced partial short-range nitrification and denitrification water treatment method according to claim 1, characterized in that: The circulation reflux ratio of the nitrification mixed solution is 3 to 5 times the water intake.

3. The micro-aerobic induction partial short-range nitrification and denitrification water treatment method according to claim 1, characterized in that: The hydraulic retention time of the microaerobic pool is 6 to 12 hours; the hydraulic retention time of the aerobic pool is 1 to 3 hours.

4. The micro-aerobic induction partial short-range nitrification and denitrification water treatment method according to claim 1 or 3, characterized in that: The circulation reflux ratio of the nitrification mixed solution in the micro-aerobic pool is 3 to 5 times the water inlet volume.

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