Sewage short-range biological denitrification control system and process, control method and readable medium, and electronic equipment

Abstract

This invention provides a short-cut biological nitrogen removal control system and process for wastewater, its control method, a readable medium, and electronic equipment. The wastewater short-cut biological nitrogen removal control system includes a reflux pump, an online ammonia nitrogen detector, an online thermometer, a pH electrode, an electromagnetic flowmeter, and a controller. The controller calculates the free ammonia concentration according to Formula I based on the ammonia nitrogen concentration, pH value, liquid temperature, and influent flow rate of the anoxic unit. It compares the free ammonia concentration with a set upper limit value. If the free ammonia concentration is greater than the set upper limit value, the reflux flow rate of the reflux system is adjusted to ensure that the free ammonia concentration does not exceed the set upper limit value. If the free ammonia concentration is less than or equal to the set upper limit value, the reflux flow rate of the reflux system remains unchanged. This invention's system can achieve rapid and stable short-cut nitrification when treating high-ammonia nitrogen wastewater and can be automatically controlled.

Description

Technical Field

[0001] The invention relates to a sewage short-range biological denitrification control system and process, a control method and a readable medium and electronic equipment thereof. Background Art

[0002] Sludge, as a by-product of wastewater treatment, refers to the solid part retained or separated in the process of treating domestic sewage or industrial wastewater. With the rapid development of urban population and industry in my country, the amount of urban sewage treatment has increased year by year, resulting in a surge in the production of sludge as the final product of sewage treatment. The treatment and disposal of residual sludge has received increasing attention and has gradually become one of the main reasons that plague the development of the sewage treatment industry. At present, the main methods of domestic sludge disposal are composting, landfilling, incineration, and manufacturing building materials.

[0003] For a long time to come, landfill will remain one of the most important methods of sludge treatment in my country. However, at present, sludge treatment in my country lags far behind sewage treatment. Among the existing sewage treatment facilities in China, less than 1 / 4 has sludge stabilization treatment facilities, and less than 1 / 10 has relatively complete treatment processes and supporting facilities. In the past 20 years of sewage treatment, a considerable proportion of sludge was directly transported out of the sewage treatment plant after being dehydrated to a moisture content of less than 80%, and was simply landfilled in abandoned mines, depressions, ditches, wastelands, etc.

[0004] In recent years, with the advancement of technology, my country has implemented a large number of sludge deep dehydration projects, and the moisture content of deep dehydrated sludge can be reduced to about 60% or even lower. After deep dehydration, the sludge volume will be reduced to less than 50% of conventional dehydration, and the shear strength of the dehydrated sludge cake will be greatly improved, which makes it possible for the sludge to be buried separately in the landfill, and can also greatly reduce the volume required for landfill. Therefore, it is necessary to carry out secondary dehydration treatment on the landfill sludge with too high moisture content in the early stage, reduce the landfill area, and reduce potential environmental risks.

[0005] Sludge dehydration will bring a large amount of sludge dehydration liquid, which is a typical high-ammonia nitrogen wastewater. The ammonia nitrogen concentration of sludge dehydration liquid is as high as 1000-3000mg / L, and the chemical oxygen demand (COD) concentration can also reach more than 1000mg / L. Direct discharge will cause serious pollution to the environment. Discharge to urban sewage treatment plants will impact the original system and seriously interfere with the stable operation of the system. With the continuous improvement of my country's sewage treatment discharge standards, the total amount of pollutants in it is also increasingly valued. Therefore, how to effectively treat sludge dehydration liquid has become an urgent problem to be solved.

[0006] Sludge dewatering liquid is a difficult point in the field of biological treatment due to its high ammonia nitrogen concentration, substrate inhibition, insufficient influent alkalinity, and lack of carbon source for denitrification. The traditional nitrification and denitrification biological denitrification process converts ammonia nitrogen into nitrate nitrogen through the action of ammonia oxidizing bacteria under aerobic conditions, and then reduces nitrate nitrogen to nitrogen gas through organic matter in the anoxic zone, thereby achieving the purpose of denitrification. Short-range biological denitrification refers to controlling the oxidation of ammonia nitrogen in the nitrite stage in the aerobic zone, oxidizing ammonia nitrogen to nitrite by ammonia oxidizing bacteria, and preventing nitrite from being further oxidized to nitrate by nitrite oxidizing bacteria, and then anoxic denitrification through organic matter, gradually reducing nitrite nitrogen to nitrogen gas. Nitrification is the process of oxidizing ammonia nitrogen to nitrate nitrogen; short-range nitrification is the process of oxidizing ammonia nitrogen to nitrite nitrogen. Semi-short-range nitrification is the process of oxidizing about half of ammonia nitrogen to nitrite nitrogen. It is necessary to control the oxidation amount of ammonia nitrogen on the basis of achieving short-range nitrification, which can be achieved by controlling the aeration volume and alkalinity dosage. The following is the reaction equation for semi-short-range nitration:

[0007]

[0008] With the gradual rise of short-term nitrification and denitrification denitrification technology, the cost of using biological technology to treat sludge dewatering liquid has been greatly reduced. However, in the process of short-term nitrification and denitrification, the stability control of nitrite oxidizing bacteria is one of the difficulties in the application of short-term nitrification biological denitrification technology. In general sewage treatment systems, ammonia nitrogen undergoes nitrification reaction. If you want to control the ammonia nitrogen in the system to be oxidized only to nitrite nitrogen, special control conditions are required. At present, the realization of short-term nitrification mostly adopts the control strategy of high pH value (7.5-8.0), high free ammonia (7-20mg / L), high temperature (30-35℃) and low dissolved oxygen (0.3-1.0mg / L) to selectively eliminate nitrifying bacteria or inhibit their activity. In high-ammonia nitrogen wastewater, the nitrification process of sewage is easily affected by the toxic effect of free ammonia. Controlling the concentration of free ammonia is one of the key factors in regulating sewage denitrification. The conventional practice is to achieve short-term nitrification by controlling the pH of the system. This technology requires the addition of a large amount of alkali to make the free ammonia concentration in the system reach a level that inhibits the activity of nitrite oxidizing bacteria. Therefore, the alkalinity of the entire system is excessive, and this technology is only applicable when the ammonia nitrogen in the influent is stable. When the ammonia nitrogen concentration in the influent fluctuates, if the amount of alkali added cannot be adjusted in time, the short-term nitrification cannot be maintained stably. Summary of the invention

[0009] In order to solve the defect that short-term nitrification is difficult to maintain stably when treating high-ammonia nitrogen sewage by short-term nitrification and denitrification technology in the prior art, the present invention provides a sewage short-term biological denitrification system and process, a control system and method, a readable medium, and an electronic device. The sewage short-term biological denitrification treatment system and treatment process of the present invention can achieve rapid and stable short-term nitrification when treating high-ammonia nitrogen sewage, and can achieve automatic control.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions.

[0011] In the first aspect, the present invention provides a sewage short-range biological denitrification control system, which is used to control the reflux volume of the reflux system in the sewage short-range biological denitrification system, including: a reflux pump, an online ammonia nitrogen detector, an online thermometer, a pH electrode, an electromagnetic flowmeter and a controller; wherein,

[0012] The reflux pump is used to adjust the reflux volume;

[0013] The online ammonia nitrogen detector is used to detect the ammonia nitrogen concentration;

[0014] The online thermometer is used to detect the temperature of the liquid;

[0015] The pH electrode is used to detect the pH value of the liquid;

[0016] The electromagnetic flowmeter is used to detect the water inlet flow rate;

[0017] The controller is used to calculate the free ammonia concentration according to formula I based on the ammonia nitrogen concentration of the anoxic unit, the pH value, the liquid temperature and the water inlet flow rate; compare the free ammonia concentration with the set upper limit value of the free ammonia concentration, and if the free ammonia concentration is greater than the upper limit value of the free ammonia concentration, adjust the reflux amount of the reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value of the free ammonia concentration, the reflux amount of the reflux system remains unchanged;

[0018] Formula I:

[0019] Wherein, FA is the free ammonia concentration, mg / L; C is the ammonia nitrogen concentration, mg / L; pH is the pH value of the aqueous phase; T is the water temperature, ℃.

[0020] In a second aspect, the present invention provides a short-cut biological denitrification process for sewage, which comprises the following steps:

[0021] S1, introducing the sewage to be treated into the pretreatment unit for pretreatment;

[0022] S2, the effluent after pretreatment enters the anoxic tank and the aerobic tank of the two or more anoxic and aerobic units connected in series in the biological treatment unit in sequence, denitrification reaction is carried out in the anoxic tank, and short-cut nitrification reaction is carried out in the aerobic tank; the effluent of one or more of the aerobic tanks is partially returned to one or more of the anoxic tanks through the reflux system, and the reflux amount of the reflux system is controlled by the sewage short-cut biological denitrification control system as described above;

[0023] S3. The effluent from the biological treatment unit enters the deep treatment unit for deep treatment.

[0024] In a third aspect, the present invention provides a method for controlling short-term biological denitrification of sewage, which adopts the short-term biological denitrification control system of sewage as described above to control the reflux amount of the reflux system in the short-term biological denitrification system of sewage, including: obtaining ammonia nitrogen concentration, pH value, liquid temperature and inlet flow rate, and calculating the free ammonia concentration according to formula I; comparing the free ammonia concentration with a set upper limit value of the free ammonia concentration, if the free ammonia concentration is greater than the upper limit value of the free ammonia concentration, adjusting the reflux amount of the reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value of the free ammonia concentration, the reflux amount of the reflux system remains unchanged.

[0025] In a fourth aspect, the present invention provides a readable medium having a non-volatile program code executable by a processor, wherein the program code enables the processor to execute the above-mentioned short-range biological denitrification control method for sewage.

[0026] In a fifth aspect, the present invention provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the computer program, the short-term biological denitrification control method for sewage as described above is implemented.

[0027] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0028] The reagents and raw materials used in the present invention are commercially available.

[0029] The positive and progressive effects of the present invention are:

[0030] 1. The present invention effectively controls the concentration of free ammonia by controlling the reflux rate, and can simultaneously achieve:

[0031] (1) Inhibit the activity of nitrite-oxidizing bacteria and achieve short-term nitrification; using reflux to control the free ammonia concentration can avoid the defects of conventional methods such as excessive alkali dosage, inability to adjust in time, and high treatment costs, making short-term nitrification rapid and stable.

[0032] (2) The effluent from the aerobic pool is returned to the anoxic pool. Nitrification occurs in the aerobic pool, causing the alkalinity to decrease and the acidity to increase. The return of the nitrification solution will replenish the alkalinity in the aerobic pool, which is beneficial to the nitrification reaction.

[0033] (3) The nitrification products undergo a "nitrification-denitrification" cycle, which is beneficial to deep nitrogen removal.

[0034] 2. The present invention is suitable for short-range biological denitrification treatment of high-concentration ammonia nitrogen wastewater (especially landfill sludge dewatering liquid), so that the effluent meets the discharge standards, and plays an important role in improving the theory and technology of high-concentration ammonia nitrogen wastewater treatment.

[0035] 3. The present invention realizes automatic control of short-range biological denitrification treatment of sewage by automatically controlling the return flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the structure of the sewage short-range biological denitrification system of Example 1.

[0037] Figure 2 This is a flow chart of the short-range biological denitrification control method for sewage in Example 1. DETAILED DESCRIPTION

[0038] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0039] In the sewage short-range biological denitrification control system of the first aspect of the present invention:

[0040] In the present invention, preferably, the sewage short-range biological denitrification system comprises a pretreatment unit, a biological treatment unit and a deep treatment unit connected in sequence along the sewage treatment direction, wherein the biological treatment unit comprises two or more anoxic aerobic units connected in series, the anoxic aerobic unit comprises an anoxic tank and an aerobic tank connected in sequence, a reflux system is provided between one or more of the aerobic tanks and one or more of the anoxic tanks, one end of the reflux system is connected to the outlet of the aerobic tank, and the other end is connected to the inlet of the anoxic tank; the step of adjusting the reflux amount of the reflux system so that the free ammonia concentration is not greater than the set upper limit value of the free ammonia concentration comprises:

[0041] K1, substituting the upper limit value of the free ammonia concentration into formula I to obtain the maximum value of the ammonia nitrogen concentration;

[0042] K2. Substitute the maximum value of the ammonia nitrogen concentration into formula II to calculate the minimum theoretical reflux volume of the reflux system:

[0043] Formula II:

[0044] Among them, C in is the influent ammonia nitrogen concentration of the biological treatment unit, mg / L; C A is the maximum value of the ammonia nitrogen concentration, mg / L; C out is the effluent ammonia nitrogen concentration of the aerobic pool connected to the inlet of the reflux system, mg / L; Q in is the inlet flow rate of the biological treatment unit, m 3 / h;Q 理论 is the minimum theoretical reflux volume of the reflux system, m 3 / h;

[0045] K3. Adjust the reflux volume of the reflux system so that the reflux volume of the reflux system is greater than or equal to the minimum theoretical reflux volume of the reflux system.

[0046] More preferably, the working efficiency of the reflux pump is calculated based on the minimum theoretical flow of the reflux system and the maximum flow of the reflux pump; the flow of the reflux pump is adjusted according to the working efficiency of the reflux pump, thereby controlling the reflux amount of the reflux system.

[0047] Preferably, at least one of the aerobic tanks has a built-in membrane component.

[0048] Among them, more preferably, the pretreatment unit includes a coagulation tank and a sedimentation tank connected in sequence; the coagulant in the coagulation tank preferably includes one or more of polyaluminum sulfate, polyferric sulfate, calcium oxide and calcium hydroxide.

[0049] Preferably, the deep treatment unit comprises an acidification tank, an oxidation tank and a neutralization tank connected in sequence. The acidic agent in the acidification tank preferably comprises hydrochloric acid. The oxidation method in the oxidation tank is preferably ozone oxidation, Fenton oxidation or persulfate oxidation. The alkaline agent in the neutralization tank preferably comprises one or more of sodium hydroxide, calcium oxide and calcium hydroxide.

[0050] In a preferred embodiment of the present invention, the biological treatment unit comprises a primary anoxic aerobic unit and a secondary anoxic aerobic unit connected in series, a first reflux system is provided between the aerobic tank of the secondary anoxic aerobic unit and the anoxic tank of the primary anoxic aerobic unit, and a second reflux system is provided between the aerobic tank of the secondary anoxic aerobic unit and the anoxic tank of the secondary anoxic aerobic unit.

[0051] In the above embodiment, preferably, the step of adjusting the reflux amount of the first reflux system so that the free ammonia concentration of the primary anoxic tank is not greater than the upper limit of the free ammonia concentration comprises:

[0052] K1. Substituting the upper limit of the free ammonia concentration into formula I to obtain the maximum value of the ammonia nitrogen concentration of the primary anoxic tank; the upper limit of the free ammonia concentration is preferably 120 to 200, for example, 150 or 160;

[0053] Formula I:

[0054]

[0055] K2. Substitute the maximum value of the ammonia nitrogen concentration of the primary anoxic tank into Formula II to calculate the minimum theoretical reflux volume of the reflux system:

[0056] Formula II:

[0057] Among them, C in is the influent ammonia nitrogen concentration of the biological treatment unit, mg / L; C A1 is the maximum ammonia nitrogen concentration in the primary anoxic pool, mg / L; C out is the effluent ammonia nitrogen concentration of the secondary aerobic pool, mg / L; Q in is the water inlet flow rate of the biological treatment unit, m 3 / h;Q 理论1 is the minimum theoretical return flow to the primary anoxic tank, m 3 / h;

[0058] K3. Adjust the reflux volume of the first reflux system so that the reflux volume of the first reflux system is greater than or equal to the minimum theoretical reflux volume of the first reflux system.

[0059] In the above embodiment, the step of adjusting the reflux amount of the second reflux system so that the free ammonia concentration of the secondary anoxic tank is not greater than the upper limit of the free ammonia concentration comprises:

[0060] K1. Substituting the upper limit value of the free ammonia concentration into formula I to obtain the maximum value of the ammonia nitrogen concentration of the secondary anoxic tank; the upper limit value of the free ammonia concentration is preferably 50 to 80, for example, 50 or 60;

[0061] Formula I:

[0062] K2. Substitute the maximum value of the ammonia nitrogen concentration of the secondary anoxic tank into Formula II to calculate the minimum theoretical reflux flow of the second reflux system:

[0063] Formula II:

[0064] Among them, C A2is the maximum ammonia nitrogen concentration in the secondary anoxic pool, mg / L; C O1 is the effluent ammonia nitrogen concentration of the primary aerobic pool, mg / L; C out is the effluent ammonia nitrogen concentration of the secondary aerobic pool, mg / L; Q in is the water inlet flow rate of the biological treatment unit, m 3 / h; Q1 is the minimum theoretical return flow to the primary anoxic tank, m 3 / h;Q 理论2 is the minimum theoretical return flow to the secondary anoxic tank, m 3 / h;

[0065] K3. Adjust the reflux volume of the second reflux system so that the reflux volume of the second reflux system is greater than or equal to the minimum theoretical reflux volume of the second reflux system.

[0066] In the present invention, the calculation formulas of Q1 and Q2 are specially designed according to the law of conservation of materials in order to achieve effective control of free ammonia without adding alkali to adjust the pH.

[0067] In the present invention, the inventors found in the research and development that the free ammonia concentration limit exists in a range through the actual feedback from the field pilot test. A1 ≤120~200, and FA A2 ≤50~80, rapid and stable short-range nitrification can be achieved.

[0068] In the present invention, the inventors found during research and development that it is a better choice to set up a two-stage anoxic aerobic unit in series in the biological treatment unit. If the number of stages is increased, the FA concentration in the subsequent anoxic / aerobic tank is too low, and the short-range nitrification effect cannot be achieved. At the same time, if there are too many staged stages, the denitrification effect may not be greatly improved, and the system process will be complicated and difficult to control.

[0069] In a short-cut biological denitrification process for sewage according to the second aspect of the present invention:

[0070] In step S1, preferably, the sewage to be treated and the coagulant are mixed in the coagulation tank for coagulation treatment; the effluent after the coagulation treatment is subjected to solid-liquid separation in a sedimentation tank to obtain pretreated effluent.

[0071] More preferably, the hydraulic retention time (HRT) of the sewage to be treated in the coagulation tank is 0.1 to 1 h.

[0072] More preferably, the solid-liquid separation method is gravity sedimentation.

[0073] More preferably, the hydraulic retention time (HRT) of the effluent after the coagulation treatment in the sedimentation tank is 0.1 to 2 hours.

[0074] In the present invention, the COD of the sewage to be treated is preferably 1000 mg / L to 10000 mg / L, the total nitrogen value is preferably 2000 mg / L to 8000 mg / L, and the total phosphorus value is preferably 50 mg / L to 500 mg / L.

[0075] In the present invention, the pH value of the sewage to be treated is preferably 5-8.

[0076] In the present invention, the sewage to be treated is preferably dehydrated liquid of landfill sludge.

[0077] In step S2, preferably, the pretreated effluent is sequentially passed through a primary anoxic aerobic unit and a secondary anoxic aerobic unit to perform primary anoxic / aerobic treatment and secondary anoxic / aerobic treatment respectively.

[0078] In step S2, preferably, the effluent after the secondary anoxic / aerobic treatment is subjected to solid-liquid separation by a membrane assembly in a secondary aerobic tank. The solid-liquid separation method is preferably a membrane separation method.

[0079] More preferably, the primary anoxic / aerobic treatment is carried out in a primary anoxic tank (primary A tank) and a primary aerobic tank (primary O tank).

[0080] More preferably, the total HRT of the pretreated effluent in the primary anoxic tank and the primary aerobic tank is 4 to 8 days. The ratio of the HRT of the pretreated effluent in the primary anoxic tank to the total HRT time is preferably 20% to 30%, and the ratio of the HRT of the pretreated effluent in the primary aerobic tank to the total HRT time is preferably 70% to 80%.

[0081] More preferably, the total HRT of the effluent after the primary anoxic / aerobic treatment in the secondary anoxic pool and the secondary aerobic pool is 4 to 10 days. The ratio of the HRT of the effluent after the primary anoxic / aerobic treatment in the secondary anoxic pool to the total HRT time is preferably 20% to 30%, and the ratio of the HRT of the effluent after the primary anoxic / aerobic treatment in the secondary aerobic pool to the total HRT time is preferably 70% to 80%.

[0082] More preferably, part of the effluent after the secondary anoxic / aerobic treatment is returned to the primary anoxic tank of the primary anoxic aerobic unit, and the return amount is Q1; part of the effluent is returned to the secondary anoxic tank of the secondary anoxic aerobic unit, and the return amount is Q2. The reflux ratio is preferably 100% to 900%. Through reflux treatment, the inhibitory effect of ammonia nitrogen in raw water can be further reduced.

[0083] In the present invention, the dissolved oxygen in the wastewater of the primary anoxic tank is preferably 0.5 mg / L to 1 mg / L.

[0084] In the present invention, the pH of the wastewater in the primary anoxic tank is preferably >6.5.

[0085] In the present invention, the dissolved oxygen in the wastewater of the primary aerobic pool is preferably 1 mg / L to 5 mg / L.

[0086] In the present invention, the pH of the wastewater in the primary aerobic tank is preferably >6.5.

[0087] In the present invention, the pH of the wastewater in the secondary anoxic tank is preferably >6.5.

[0088] In the present invention, the dissolved oxygen in the wastewater of the secondary aerobic pool is preferably 1 mg / L to 5 mg / L.

[0089] In the present invention, the pH of the wastewater in the secondary aerobic tank is preferably >6.5.

[0090] In step S3, preferably, the deep processing step includes:

[0091] 1) The effluent from the biological treatment unit enters the acidification tank of the deep treatment unit to adjust the pH value;

[0092] 2) introducing the effluent after adjusting the pH value into an oxidation pond for oxidation treatment;

[0093] 3) The effluent after the oxidation treatment is introduced into a neutralization tank, the pH value is adjusted to be neutral, and the effluent is discharged.

[0094] More preferably, the deep processing step satisfies at least one of the following conditions:

[0095] Acidic agent is added to adjust the pH value of the sludge dewatering liquid to 2-6; and the acidic agent is hydrochloric acid.

[0096] The hydrochloric acid is preferably concentrated hydrochloric acid, and the concentration of the hydrochloric acid is preferably ≥ 20%.

[0097] Wherein, the total HRT of the effluent from the biological treatment unit in the acidification tank is preferably 0.1 to 0.5 h.

[0098] The effluent after adjusting the pH value is introduced into an oxidation pond for oxidation treatment, which can further reduce the pollutant concentration of the wastewater. The oxidation treatment method can be ozone oxidation, Fenton oxidation or persulfate oxidation.

[0099] The total HRT of the effluent after adjusting the pH value in the oxidation pond is preferably 0.1 to 1 h.

[0100] Wherein, the alkaline agent added to the neutralization tank is preferably one or more of sodium hydroxide, calcium oxide and calcium hydroxide.

[0101] Wherein, in the step 3), various indicators of the effluent can all meet the requirements of Grade A in the "Water Quality Standards for Sewage Discharge into Urban Sewers" (CJ 343-2010) (ammonia nitrogen ≤ 45 mg / L, total nitrogen ≤ 70 mg / L, COD ≤ 500 mg / L, SS ≤ 400 mg / L).

[0102] In a method for controlling short-range biological denitrification of sewage according to the third aspect of the present invention:

[0103] In a preferred embodiment of the present invention, the sewage short-range biological denitrification control method adopts the sewage short-range biological denitrification control system as described above to control the reflux amount of the reflux system in the sewage short-range biological denitrification system, the biological treatment unit of the sewage short-range biological denitrification control system comprises a primary anoxic aerobic unit and a secondary anoxic aerobic unit connected in series, a first reflux system is provided between the aerobic tank of the secondary anoxic aerobic unit and the anoxic tank of the primary anoxic aerobic unit; a second reflux system is provided between the aerobic tank of the secondary anoxic aerobic unit and the anoxic tank of the secondary anoxic aerobic unit, respectively;

[0104] The sewage short-range biological denitrification control method comprises:

[0105] S1, obtain ammonia nitrogen concentration, pH value and water flow rate,

[0106] S2. Calculate the free ammonia concentration of the primary anoxic tank according to the formula I; compare the free ammonia concentration of the primary anoxic tank with the upper limit value of the free ammonia concentration of the primary anoxic tank; if the free ammonia concentration is greater than the upper limit value of the free ammonia concentration, adjust the reflux amount of the first reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value of the free ammonia concentration, the reflux amount of the first reflux system remains unchanged; wherein, the step of adjusting the reflux amount of the first reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration is the same as before.

[0107] S3. Calculate the free ammonia concentration of the secondary anoxic tank according to the formula I; compare the free ammonia concentration of the secondary anoxic tank with the upper limit value of the free ammonia concentration of the secondary anoxic tank; if the free ammonia concentration is greater than the upper limit value of the free ammonia concentration, adjust the reflux amount of the second reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value of the free ammonia concentration, the reflux amount of the second reflux system remains unchanged; wherein, the step of adjusting the reflux amount of the second reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration is the same as before.

[0108] In the present invention, the step of adjusting the reflux amount of the reflux system so that the free ammonia concentration is not greater than the set upper limit value of the free ammonia concentration is as described above.

[0109] In the present invention, the sewage short-range biological denitrification control system is as described above.

[0110] In the readable medium of the fourth aspect and the electronic device of the fifth aspect of the present invention:

[0111] The readable medium is a computer-readable medium having a non-volatile program code executable by a processor. A computer program is stored on the computer-readable medium. When the computer program is run by the processor, the above-mentioned sewage short-range biological denitrification control method is executed.

[0112] The computer program product provided in the embodiment of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the method described in the previous method embodiment. The specific implementation can be found in the method embodiment and will not be repeated here.

[0113] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0114] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 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 the present invention can be understood according to specific circumstances.

[0115] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read Only Memory), random access memory (RAM, Ran Access Memory), disk or optical disk, etc., various media that can store program codes.

[0116] Example 1

[0117] This embodiment provides a sewage short-range biological denitrification control system, which is used to control the reflux volume of the reflux system in the sewage short-range biological denitrification system, including: a reflux pump, an online ammonia nitrogen detector, an online thermometer, a pH electrode, an electromagnetic flowmeter and a controller; wherein,

[0118] Reflux pump, used to adjust the reflux volume;

[0119] Online ammonia nitrogen detector, used to detect ammonia nitrogen concentration;

[0120] Online thermometer, used to detect liquid temperature;

[0121] pH electrode, used to detect the pH value of liquid;

[0122] Electromagnetic flowmeter, used to detect water inlet flow;

[0123] The controller is used to calculate the free ammonia concentration according to formula I based on the ammonia nitrogen concentration, pH value, liquid temperature and water inlet flow rate of the anoxic unit; compare the free ammonia concentration with the upper limit value set for the free ammonia concentration, and if the free ammonia concentration is greater than the upper limit value set for the free ammonia concentration, adjust the reflux amount of the reflux system so that the free ammonia concentration is not greater than the upper limit value set for the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value set for the free ammonia concentration, the reflux amount of the reflux system remains unchanged;

[0124] Formula I:

[0125] Where FA is the free ammonia concentration, mg / L; C A1 is the ammonia nitrogen concentration of the anoxic unit, mg / L; pH is the pH value of the water phase; T is the water temperature, °C;

[0126] The sewage short-range biological denitrification control system of this embodiment also includes a pretreatment unit, a biological treatment unit and a deep treatment unit connected in sequence along the sewage treatment direction, such as Figure 1 shown.

[0127] Wherein, the biological treatment unit comprises a first anoxic aerobic unit and a second anoxic aerobic unit connected in series, a first reflux system is arranged between the aerobic tank of the second anoxic aerobic unit and the anoxic tank of the first anoxic aerobic unit, and the first reflux system comprises a first reflux pump; a second reflux system is arranged between the aerobic tank of the second anoxic aerobic unit and the anoxic tank of the second anoxic aerobic unit, and the second reflux system comprises a second reflux pump.

[0128] Among them, both the primary aerobic pool and the secondary aerobic pool are equipped with membrane components.

[0129] The pretreatment unit includes a coagulation tank and a sedimentation tank which are connected in sequence.

[0130] The deep treatment unit includes an acidification tank, an oxidation tank and a neutralization tank which are connected in sequence.

[0131] In this embodiment, the step of adjusting the reflux amount of the first reflux system so that the free ammonia concentration in the primary anoxic tank is not greater than the upper limit of the free ammonia concentration includes:

[0132] K1. Substitute the upper limit of the free ammonia concentration into formula I to obtain the maximum value of the ammonia nitrogen concentration in the primary anoxic pool; the upper limit of the free ammonia concentration is 150;

[0133] Formula I:

[0134]

[0135] K2. Substitute the maximum value of the ammonia nitrogen concentration in the primary anoxic tank into Formula II to calculate the minimum theoretical reflux flow of the reflux system:

[0136] Formula II:

[0137] Among them, C in is the influent ammonia nitrogen concentration of the biological treatment unit, mg / L; C A1 is the maximum ammonia nitrogen concentration in the primary anoxic pool, mg / L; C out is the effluent ammonia nitrogen concentration of the secondary aerobic pool, mg / L; Q in is the inlet flow rate of the biological treatment unit, m 3 / h;Q 理论1 is the minimum theoretical return flow to the primary anoxic tank, m 3 / h;

[0138] K3. Adjust the reflux amount of the first reflux system so that the reflux amount of the first reflux system is greater than or equal to the minimum theoretical reflux amount of the first reflux system;

[0139] Specifically, the working efficiency of the first reflux pump is calculated based on the minimum theoretical flow of the first reflux system and the maximum flow of the first reflux pump; the flow of the first reflux pump is adjusted according to the working efficiency of the first reflux pump, thereby controlling the reflux volume of the first reflux system.

[0140] In this embodiment, the step of adjusting the reflux amount of the second reflux system so that the free ammonia concentration in the secondary anoxic tank is not greater than the upper limit of the free ammonia concentration includes:

[0141] K1. Substitute the upper limit of the free ammonia concentration into formula I to obtain the maximum value of the ammonia nitrogen concentration in the secondary anoxic pool; the upper limit of the free ammonia concentration is 50;

[0142] Formula I:

[0143] K2. Substitute the maximum value of the ammonia nitrogen concentration in the secondary anoxic tank into Formula II to calculate the minimum theoretical reflux flow of the second reflux system:

[0144] Formula II:

[0145] Among them, C A2 is the maximum ammonia nitrogen concentration in the secondary anoxic pool, mg / L; C O1 is the effluent ammonia nitrogen concentration of the primary aerobic pool, mg / L; C out is the effluent ammonia nitrogen concentration of the secondary aerobic pool, mg / L; Q in is the water inlet flow rate of the biological treatment unit, m 3 / h; Q1 is the minimum theoretical return flow to the primary anoxic tank, m 3 / h;Q 理论2 is the theoretical return flow to the secondary anoxic tank, m 3 / h;

[0146] K3, adjusting the reflux amount of the second reflux system so that the reflux amount of the second reflux system is greater than or equal to the minimum theoretical reflux amount of the second reflux system;

[0147] Specifically, the working efficiency of the second reflux pump is calculated based on the minimum theoretical flow of the second reflux system and the maximum flow of the second reflux pump; the flow of the second reflux pump is adjusted according to the working efficiency of the second reflux pump, thereby controlling the reflux volume of the second reflux system.

[0148] This embodiment also provides a short-range biological denitrification process for sewage, which comprises the following steps:

[0149] S1. Introducing the sewage to be treated into the pretreatment unit for pretreatment;

[0150] S2, the effluent after pretreatment enters the anoxic tank and the aerobic tank of the two or more anoxic and aerobic units connected in series in the biological treatment unit in sequence, denitrification reaction is carried out in the anoxic tank, and short-cut nitrification reaction is carried out in the aerobic tank; the effluent of one or more aerobic tanks is partially returned to one or more anoxic tanks through the reflux system, and the reflux amount of the reflux system is controlled by the above sewage short-cut biological denitrification control system;

[0151] S3. The effluent from the biological treatment unit enters the deep treatment unit for deep treatment.

[0152] The sewage to be treated in this embodiment is sludge dewatering liquid, which has the characteristics of high COD, high total nitrogen, and high ammonia nitrogen. The main physical and chemical indicators are shown in Table 1 below.

[0153] Table 1 Physicochemical properties of sludge low temperature carbonization dehydrated liquid of Example 1

[0154] index pH COD(mg / L) Total nitrogen (mg / L) Ammonia nitrogen (mg / L) Numeric 6.5 1476～4800 1685～3326 1613～3125

[0155] See attached Figure 1 , which illustrates the specific steps of the short-range biological denitrification process for sewage in this example as follows: the sludge dehydrated liquid first enters the coagulation tank, and the coagulant calcium oxide is added for coagulation treatment. The wastewater stays in the coagulation tank for 0.5 hours. The wastewater after coagulation has good sedimentation performance and is very suitable for solid-liquid separation by gravity sedimentation; it then enters the sedimentation tank and stays for 30 minutes for solid-liquid separation; the supernatant successively enters the primary anoxic / aerobic system, the secondary anoxic / aerobic system, the acidification tank, the oxidation tank and the neutralization tank, among which the HRT of the primary anoxic tank is 1 day (the influent flow includes the diluted return water from the secondary aerobic tank), and the HRT in the primary aerobic tank is 5 days; the HRT of the secondary anoxic tank is 3 days (the influent flow includes the diluted return water from the secondary aerobic tank), and the HRT in the secondary aerobic tank is 1 day; the reflux flow from the secondary aerobic tank to the primary anoxic tank is Q1, and the flow rate is Q2. By real-time detection of the ammonia nitrogen concentration in the primary anoxic tank, calculating the free ammonia concentration in the primary anoxic tank, and controlling the size of Q1, the free ammonia concentration in the primary anoxic tank is ≤150mg / L; the reflux volume from the secondary aerobic tank to the secondary anoxic tank is Q2. By real-time detection of the ammonia nitrogen concentration in the secondary anoxic tank, calculating the free ammonia concentration in the secondary anoxic tank, and controlling the size of Q2, the free ammonia concentration in the secondary anoxic tank is ≤50mg / L, thereby achieving rapid start-up and stable operation of short-range nitrification; the activities of nitrification and denitrification are very high; the HRT in the acidification tank is 30 minutes, the acidic agent added is hydrochloric acid, and the pH value is adjusted to 2; the HRT in the oxidation tank is 20 minutes, and the added agents are potassium monopersulfate and ferrous sulfate heptahydrate; the HRT in the neutralization tank is 30 minutes, and the alkaline agent added is sodium hydroxide, and the pH value is adjusted to 7.

[0156] This embodiment 1 provides a method for controlling the short-range biological denitrification of sewage, which uses the above short-range biological denitrification control system for sewage to control the reflux volume of the reflux system in the short-range biological denitrification system of sewage, such as Figure 2 As shown, including:

[0157] S1, obtain ammonia nitrogen concentration, pH value and water flow rate,

[0158] S2, according to formula I calculate the free ammonia concentration of the first anoxic pool; the free ammonia concentration of the first anoxic pool and the upper limit value (FA A1≤150mg / L) for comparison, if the free ammonia concentration is greater than the upper limit value set for the free ammonia concentration, the reflux amount of the first reflux system is adjusted so that the free ammonia concentration is not greater than the upper limit value set for the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value set for the free ammonia concentration, the reflux amount of the first reflux system remains unchanged; wherein, the step of adjusting the reflux amount of the first reflux system so that the free ammonia concentration is not greater than the upper limit value set for the free ammonia concentration is the same as before.

[0159] S3, according to the above formula 1 calculate the free ammonia concentration of the secondary anoxic pool; the free ammonia concentration of the secondary anoxic pool and the upper limit value (FA A2 ≤50mg / L) for comparison, if the free ammonia concentration is greater than the upper limit value set for the free ammonia concentration, the reflux amount of the second reflux system is adjusted so that the free ammonia concentration is not greater than the upper limit value set for the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value set for the free ammonia concentration, the reflux amount of the second reflux system remains unchanged; wherein, the step of adjusting the reflux amount of the second reflux system so that the free ammonia concentration is not greater than the upper limit value set for the free ammonia concentration is the same as before.

[0160] After the short-range biological denitrification control system of sewage in this embodiment 1 controls the reflux volume of the first reflux system and the second reflux system, the short-range biological denitrification control system of sewage in this embodiment is processed by the process flow, and the highly polluted sludge dehydrated liquid meets the requirements of Grade A in the "Water Quality Standard for Sewage Discharged into Urban Sewers" (CJ 343-2010). After continuous operation for 100 days according to the above process, the average concentrations of effluent COD, ammonia nitrogen and total nitrogen are lower than 500, 50 and 100 mg / L respectively. The average removal rates of COD, ammonia nitrogen and total nitrogen are 78.9%, 97.8% and 95.8% respectively.

[0161] The embodiments described above are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. A sewage short-range biological denitrification control system, characterized in that: It is used to control the reflux volume of the reflux system in the short-range biological denitrification system of sewage, and includes: a reflux pump, an online ammonia nitrogen detector, an online thermometer, a pH electrode, an electromagnetic flowmeter and a controller; among them, The reflux pump is used to adjust the reflux volume; The online ammonia nitrogen detector is used to detect the ammonia nitrogen concentration; The online thermometer is used to detect the temperature of the liquid; The pH electrode is used to detect the pH value of the liquid; The electromagnetic flowmeter is used to detect the water inlet flow rate; The controller is used to calculate the free ammonia concentration according to formula I based on the ammonia nitrogen concentration, the pH value, the liquid temperature and the inlet water flow rate; compare the free ammonia concentration with the set upper limit value of the free ammonia concentration, and if the free ammonia concentration is greater than the set upper limit value of the free ammonia concentration, adjust the reflux amount of the reflux system so that the free ammonia concentration is not greater than the upper limit value of the free ammonia concentration; if the free ammonia concentration is less than or equal to the upper limit value of the free ammonia concentration, the reflux amount of the reflux system remains unchanged; Formula I: Wherein, FA is the free ammonia concentration, mg / L; C is the ammonia nitrogen concentration, mg / L; pH is the pH value of the aqueous phase; T is the water temperature, °C; The sewage short-range biological denitrification system comprises a pretreatment unit, a biological treatment unit and a deep treatment unit connected in sequence along the sewage treatment direction, wherein the biological treatment unit comprises two or more stages of anoxic aerobic units connected in series, the anoxic aerobic unit comprises an anoxic tank and an aerobic tank connected in sequence, a reflux system is provided between one or more of the aerobic tanks and one or more of the anoxic tanks, one end of the reflux system is connected to the outlet of the aerobic tank, and the other end is connected to the inlet of the anoxic tank; the step of adjusting the reflux amount of the reflux system so that the free ammonia concentration is not greater than the upper limit of the free ammonia concentration comprises: K1, substituting the upper limit value of the free ammonia concentration into formula I to obtain the maximum value of the ammonia nitrogen concentration; K2. Substitute the maximum value of the ammonia nitrogen concentration into formula II to calculate the minimum theoretical reflux volume of the reflux system: Formula II: Among them, C in is the influent ammonia nitrogen concentration of the biological treatment unit, mg / L; C A is the maximum value of the ammonia nitrogen concentration, mg / L; C out is the effluent ammonia nitrogen concentration of the aerobic pool connected to the inlet of the reflux system, mg / L; Q in is the water inlet flow rate of the biological treatment unit, m 3 / h;Q 理论 is the minimum theoretical reflux volume of the reflux system, m 3 / h; K3. Adjust the reflux volume of the reflux system so that the reflux volume of the reflux system is greater than or equal to the minimum theoretical reflux volume of the reflux system.

2. The sewage short-range biological denitrification control system according to claim 1, characterized in that: The working efficiency of the reflux pump is calculated based on the minimum theoretical flow of the reflux system and the maximum flow of the reflux pump; the reflux volume of the reflux pump is adjusted according to the working efficiency of the reflux pump, thereby controlling the reflux volume of the reflux system.

3. The sewage short-range biological denitrification control system according to claim 1 is characterized in that: The sewage short-cut biological denitrification system meets one or more of the following conditions: (1) at least one of the aerobic tanks has a built-in membrane module; (2) The pretreatment unit comprises a coagulation tank and a sedimentation tank connected in sequence; and, (3) The deep treatment unit includes an acidification tank, an oxidation tank and a neutralization tank connected in sequence.

4. The sewage short-range biological denitrification control system according to claim 3 is characterized in that: The coagulant in the coagulation tank includes one or more of polyaluminium sulfate, polyferric sulfate, calcium oxide and calcium hydroxide.

5. The sewage short-range biological denitrification control system according to claim 1 is characterized in that: The biological treatment unit comprises a primary anoxic aerobic unit and a secondary anoxic aerobic unit connected in series, a first reflux system is provided between the aerobic tank of the secondary anoxic aerobic unit and the anoxic tank of the primary anoxic aerobic unit, and a second reflux system is provided between the aerobic tank of the secondary anoxic aerobic unit and the anoxic tank of the secondary anoxic aerobic unit.

6. The sewage short-range biological denitrification control system according to claim 5 is characterized in that: The step of adjusting the reflux amount of the first reflux system so that the free ammonia concentration of the primary anoxic tank is not greater than the upper limit of the free ammonia concentration comprises: K1, substituting the upper limit value of the free ammonia concentration into formula I1 to obtain the maximum value of the ammonia nitrogen concentration in the primary anoxic tank; Formula I1: K2. Substitute the maximum value of the ammonia nitrogen concentration of the primary anoxic tank into formula II1 to calculate the minimum theoretical reflux volume of the reflux system: Formula II1: Among them, C in is the influent ammonia nitrogen concentration of the biological treatment unit, mg / L; C A1 is the maximum ammonia nitrogen concentration in the primary anoxic pool, mg / L; C out is the effluent ammonia nitrogen concentration of the secondary aerobic pool, mg / L; Q in is the water inlet flow rate of the biological treatment unit, m 3 / h;Q 理论1 is the minimum theoretical return flow to the primary anoxic tank, m 3 / h; K3. Adjust the reflux volume of the first reflux system so that the reflux volume of the first reflux system is greater than or equal to the minimum theoretical reflux volume of the first reflux system.

7. The sewage short-range biological denitrification control system according to claim 6 is characterized in that: The upper limit of the free ammonia concentration is 120-200.

8. The sewage short-range biological denitrification control system according to claim 7 is characterized in that: The upper limit of the free ammonia concentration is 150 or 160.

9. The sewage short-range biological denitrification control system according to claim 5, characterized in that: The step of adjusting the reflux amount of the second reflux system so that the free ammonia concentration of the secondary anoxic tank is not greater than the upper limit of the free ammonia concentration comprises: K1, substituting the upper limit value of the free ammonia concentration into formula I2 to obtain the maximum value of the ammonia nitrogen concentration in the secondary anoxic tank; Official I2: K2, the maximum value of the ammonia nitrogen concentration of the secondary anoxic tank is brought into formula II2 to calculate the minimum theoretical reflux flow of the second reflux system: Formula II2: Among them, C A2 is the maximum ammonia nitrogen concentration in the secondary anoxic pool, mg / L; C O1 is the effluent ammonia nitrogen concentration of the primary aerobic pool, mg / L; C out is the effluent ammonia nitrogen concentration of the secondary aerobic pool, mg / L; Q in is the water inlet flow rate of the biological treatment unit, m 3 / h; Q1 is the minimum theoretical reflux flow back to the primary anoxic tank, m 3 / h;Q 理论2 is the minimum theoretical return flow to the secondary anoxic tank, m 3 / h; K3. Adjust the reflux volume of the second reflux system so that the reflux volume of the second reflux system is greater than or equal to the minimum theoretical reflux volume of the reflux system.

10. The sewage short-range biological denitrification control system according to claim 9, characterized in that: The upper limit of the free ammonia concentration is 50-80.

11. The sewage short-range biological denitrification control system according to claim 10, characterized in that: The upper limit of the free ammonia concentration is 50 or 60.

12. A short-cut biological denitrification process for sewage, characterized in that: It includes the following steps: S1. Introducing the sewage to be treated into the pretreatment unit for pretreatment; S2, the effluent after pretreatment enters the anoxic tank and the aerobic tank of the two or more anoxic and aerobic units connected in series in the biological treatment unit in sequence, denitrification reaction is carried out in the anoxic tank, and short-cut nitrification reaction is carried out in the aerobic tank; the effluent of one or more of the aerobic tanks is partially returned to one or more of the anoxic tanks through the reflux system, and the reflux amount of the reflux system is controlled by the sewage short-cut biological denitrification control system according to any one of claims 1 to 11; S3. The effluent from the biological treatment unit enters a deep treatment unit for deep treatment.

13. A method for controlling short-range biological denitrification of sewage, characterized in that: The method adopts the sewage short-range biological denitrification control system as described in any one of claims 1 to 11 to control the reflux amount of the reflux system in the sewage short-range biological denitrification system, including: obtaining ammonia nitrogen concentration, pH value, liquid temperature and water inlet flow, and calculating the free ammonia concentration according to formula I; comparing the free ammonia concentration with the set upper limit value of the free ammonia concentration, if the free ammonia concentration is greater than the set upper limit value of the free ammonia concentration, adjusting the reflux amount of the reflux system so that the free ammonia concentration is not greater than the set upper limit value of the free ammonia concentration; if the free ammonia concentration is less than or equal to the set upper limit value of the free ammonia concentration, the reflux amount of the reflux system remains unchanged.

14. A readable medium having a non-volatile program code executable by a processor, characterized in that: The program code enables the processor to execute the sewage short-range biological denitrification control method as described in claim 13.

15. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the computer program, the sewage short-term biological denitrification control method as described in claim 13 is implemented.

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