Sewage treatment method and multi-carbon-source adding system

Abstract

The invention provides a sewage treatment method and a multi-carbon-source adding system, and belongs to the technical field of sewage treatment.The sewage treatment method comprises the steps that S10, adding valves are arranged at the starting end, the middle end and the tail end of an anoxic zone of a sewage treatment pond respectively, and a temperature sensor is arranged at the water inlet end, located at the starting end, of the anoxic zone; s20, a methanol storage tank and a sodium acetate storage tank which are communicated with the feeding pipeline are arranged, and an electric control valve is arranged at the bottom of each storage tank; s30, when the temperature exceeds a first preset value, the feeding valves at the initial end and the tail end are opened, and when the temperature is smaller than or equal to the first preset value, the feeding valves at the middle end and the tail end are opened; and S40, when the nitrogen value exceeds the second preset value, whether the reading of the temperature sensor is lower than the first preset value or not is judged, if yes, the storage tank corresponding to sodium acetate is opened, if not, the storage tank corresponding to methanol is opened, and when the nitrogen value is equal to or smaller than the second preset value, the opening state of the currently used storage tank is maintained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sewage treatment, and particularly relates to a sewage treatment method and a multi-carbon source feeding system. BACKGROUND

[0002] In the field of sewage treatment, when the carbon-nitrogen ratio in the sewage inflow is low and the system has strict requirements on total nitrogen removal efficiency, the sewage needs to be treated to ensure that the treatment effect meets the production requirements. The commonly used method is carbon source feeding. By feeding a single carbon source into the sewage, energy and material basis can be provided for microorganisms to ensure normal metabolism, thereby efficiently removing nitrogen and phosphorus pollutants in the sewage.

[0003] The disadvantages of traditional carbon source feeding are as follows: (1) A single carbon source can only selectively promote the growth of specific microorganisms, leading to an imbalance in the bacterial flora structure in the activated sludge. Once the water quality or operating parameters fluctuate, the system is prone to problems such as sludge activity decline and treatment efficiency drop. This method cannot adapt to changing water environments and is difficult to cope with sudden changes in water quality, resulting in poor treatment effect of the sewage. (2) When switching from one carbon source to another, due to the large volume of the carbon source storage container, the distance between adjacent containers is far, and the volume of each control valve in the corresponding sewage treatment system is large. This process needs to be operated manually, which not only consumes a lot of time in the transfer position, but also consumes a lot of time cost and labor cost when opening and closing the valve, with a lag in response, affecting the treatment efficiency of the sewage. SUMMARY

[0004] The present application provides a sewage treatment method and a multi-carbon source feeding system, which aims to solve the technical problems of the existing single carbon source feeding treatment mode that cannot adapt to changing water environments, poor treatment effect of the sewage, high labor cost and low treatment efficiency.

[0005] In a first aspect, the present application provides a sewage treatment method, comprising: S10: A temperature sensor is arranged at the inflow end of the anoxic zone at the beginning end of the sewage treatment tank; S20: Methanol storage tanks and sodium acetate storage tanks are arranged in communication with the feeding pipe. Each bottom of the storage tanks is provided with an electric control valve and a feeding pipe. Each feeding pipe is provided with three feeding valves corresponding to the beginning end, the middle end and the end of the anoxic zone; S30: The electric control valve and the temperature sensor are connected to the controller. When the temperature exceeds the first preset value, the feeding valves at the beginning end and the end are opened. When the temperature is less than or equal to the first preset value, the feeding valves at the middle end and the end are opened. S40: a total nitrogen sensor is arranged at the outlet pipe of the aerobic zone of the sewage treatment tank, the total nitrogen sensor is connected to the controller, when the nitrogen value exceeds the second preset value, it is judged whether the reading of the temperature sensor is lower than the first preset value, if lower, the corresponding storage tank of sodium acetate is opened, if equal to or greater than the first preset value, the corresponding storage tank of methanol is opened, when the nitrogen value is equal to or less than the second preset value, the opening state of the current storage tank is maintained.

[0006] Compared with the prior art, the scheme shown in the embodiments of the present application determines the opening number and position of the dosing valve at the top of the anoxic zone through measurement of the inlet water temperature, determines the type of carbon source (methanol or sodium acetate) to be put into the anoxic zone according to the measurement of the inlet water temperature and the total nitrogen of the outlet water, and the dosing valve is opened at two positions at the same time, so that carbon source is available in the entire sewage treatment tank at high temperature, avoiding incomplete denitrification due to insufficient carbon source, making the total nitrogen concentration of the outlet water lower and more stable, improving the carbon source utilization rate at low temperature, ensuring that the necessary denitrification efficiency is maintained under poor water temperature conditions, preventing the system from collapsing due to low temperature, avoiding excessive consumption at the beginning under high temperature conditions, avoiding blindly increasing the carbon source dosage to care for the end, avoiding carbon source penetration waste under low temperature conditions, and achieving on-demand distribution and precise dosing, thereby saving carbon source reagent costs under the premise of achieving the same denitrification effect, avoiding excessive carbon source from entering the aerobic zone, ensuring the oxygen required by nitrifying bacteria and the survival advantage, ensuring effective removal of ammonia nitrogen, reducing the oxygen consumption of the aerobic zone due to decomposition of excess carbon source, and correspondingly reducing the aeration amount of the fan (used to provide oxygen to the aerobic zone), thereby further saving energy consumption, effectively controlling the outlet water COD and TN to reach the standard, reducing the risk of outlet water quality fluctuations caused by improper carbon source addition, and controlling the opening and closing and opening degree of the dosing valve and the electric control valve through the controller, realizing rapid switching of the opening position of the dosing valve and the type of carbon source, flexibly responding to the fluctuation state of the water quality, and ensuring the treatment effect of the sewage.

[0007] In combination with the first aspect, in a possible implementation manner, a glucose storage tank is further included, and the glucose storage tank is also provided with an electric control valve, a feeding pipeline and a dosing valve. When the nitrogen value exceeds the second preset value and the reading of the temperature sensor is equal to or greater than the first preset value, the controller judges whether the methanol corresponding storage tank is normal, if normal, the methanol corresponding storage tank is opened, and if not normal, the glucose corresponding storage tank is opened.

[0008] In combination with the first aspect, in a possible implementation manner, an inlet water flow meter is arranged at the inlet end of the anoxic zone, and a metering pump is arranged on each of the storage tanks, and the inlet water flow meter and the metering pump are in communication connection with the controller.

[0009] In combination with the first aspect, in a possible implementation manner, a leakage alarm is arranged on the methanol storage tank.

[0010] With reference to the first aspect, in a possible implementation manner, when the nitrogen value is equal to or less than the second preset value, it is determined whether the amount of sodium acetate exceeds a third preset value, and if yes, the methanol storage tank is switched on, and if no, the current state of the storage tank is maintained.

[0011] With reference to the first aspect, in a possible implementation manner, when switching from the methanol storage tank to the sodium acetate storage tank, the opening degree of the sodium acetate storage tank gradually increases within a preset time range, and the opening degree of the methanol storage tank gradually decreases until the methanol storage tank is closed. Alternatively, when switching from the sodium acetate storage tank to the methanol storage tank, the opening degree of the methanol storage tank gradually increases within a preset time range, and the opening degree of the sodium acetate storage tank gradually decreases until the sodium acetate storage tank is closed.

[0012] With reference to the first aspect, in a possible implementation manner, the preset time range is 20 minutes, and the proportion of the carbon source corresponding to the storage tank that is turned on last is increased by 10% every 2 minutes.

[0013] In a second aspect, the present application also provides a multi-carbon source dosing system for implementing the above-mentioned sewage treatment method, which comprises: a sewage treatment tank comprising an anoxic zone and an aerobic zone that are in communication with each other, a water inlet pipe is arranged at the beginning of the anoxic zone, a water outlet pipe is arranged at the end of the aerobic zone, a water inlet flow meter and a temperature sensor are arranged on the water inlet pipe, and a total nitrogen sensor is arranged on the water outlet pipe; three dosing modules arranged above the anoxic zone, each of the dosing modules comprising a feeding pipe and three dosing valves arranged on the feeding pipe, and the three dosing valves are arranged at the beginning, the middle and the end of the anoxic zone, respectively; a carbon source module comprising three storage tanks corresponding to the dosing modules one by one, and each of the storage tanks is provided with an electric control valve and a metering pump at the bottom; a controller for controlling the opening and closing and opening degree of the dosing valves and the electric control valves, and receiving the working parameters of the total nitrogen sensor, the temperature sensor and the metering pump.

[0014] Compared with the prior art, the scheme shown in the embodiments of the present application can realize real-time acquisition of sewage treatment parameters (water inlet flow, water inlet temperature, water outlet total nitrogen, etc.) through the communication connection of the controller, the sensor and the flow meter, the sensor is directly connected with the controller, and manual sampling is replaced, so that not only the hysteresis of manual detection is avoided, but also the controller can be provided with accurate and continuous original parameters, thereby ensuring the accurate control of the carbon source dosing position, the carbon source type and the carbon source dosing amount; the three storage tanks are respectively filled with methanol, sodium acetate and glucose, and are provided with electric control valves and metering pumps, so that the accurate dosing of the carbon source can be realized in combination with the dosing valves, and different working conditions and water body environments can be flexibly adjusted.

[0015] With reference to the second aspect, in a possible implementation manner, the stirring machine is arranged in the anoxic zone.

[0016] With reference to the second aspect, in a possible implementation manner, the electrically-controlled valve is a pneumatic butterfly valve. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A structural schematic diagram of the multi-carbon source dosing system provided by the embodiment of the present application is shown in the figure. Figure 2 A control principle of the sewage treatment method provided by the embodiment of the present application is shown in the figure. Figure 1 ; Figure 3 A control principle of the sewage treatment method provided by the embodiment of the present application is shown in the figure. Figure 2 .

[0018] REFERENCE SIGNS: 10 - sewage treatment tank; 11 - anoxic zone; 12 - aerobic zone; 13 - water inlet pipe; 14 - flow meter; 15 - total nitrogen sensor; 16 - temperature sensor; 20 - feed pipe; 21 - dosing valve; 30 - storage tank; 31 - electrically-controlled valve; 32 - metering pump; 40 - stirring machine. DETAILED DESCRIPTION

[0019] In order to make the technical problems to be solved by the present application, the technical solutions and the beneficial effects more clearly understood, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not intended to limit the present application.

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0021] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of a feature, step, operation, device, component and / or their combination.

[0022] The foregoing is considered as merely illustrative of the principles of the application, and not in limitation thereof since modifications of the teachings of the application will occur to those skilled in the art upon reading this disclosure. For example, the relative positioning of the components and steps illustrated in the drawings, the numerical expressions and values set forth in the examples, and the like, are not to be construed as limiting the scope of the application. Also, it is to be understood that the dimensions of the various parts shown in the drawings are not to scale as the drawings are shown for purposes of convenience and to facilitate description. Techniques, methods, and apparatus known to those of ordinary skill are not discussed in detail but should be considered as part of the description unless otherwise noted in context. In all examples shown and discussed herein, any specific value is to be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0023] In the description of the present application, it needs to be understood that the indicated orientation or positional relationship is generally based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and in the absence of the opposite indication, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0024] Please refer to Figures 2 to 3 The sewage treatment method provided by the present application will be described. The sewage treatment method comprises: S10: A temperature sensor 16 is arranged at the water inlet end of the anoxic zone 11 at the starting end of the sewage treatment tank 10; S20: A methanol storage tank and a sodium acetate storage tank in communication with the feed pipe 20 are arranged, and each storage tank 30 is provided with an electric control valve 31 and a feed pipe 20, and each feed pipe 20 is provided with three dosing valves 21, and the three dosing valves 21 correspond to the starting end, the middle end and the end of the anoxic zone 11; S30: The electric control valve 31 and the temperature sensor 16 are both connected to the controller, when the temperature exceeds the first preset value, the dosing valves 21 at the starting end and the end are opened, and when the temperature is less than or equal to the first preset value, the dosing valves 21 at the middle end and the end are opened; S40: A total nitrogen sensor 15 is arranged at the water outlet pipe of the aerobic zone 12 of the sewage treatment tank 10, and the total nitrogen sensor 15 is connected to the controller, when the nitrogen value exceeds the second preset value, it is judged whether the reading of the temperature sensor 16 is lower than the first preset value, if lower, the corresponding storage tank 30 of sodium acetate is opened, if equal to or greater than the first preset value, the corresponding storage tank 30 of methanol is opened, and when the nitrogen value is equal to or less than the second preset value, the opening state of the current storage tank 30 is maintained.

[0025] It should be noted that the first preset value is in the range of 12℃-15℃; when the temperature is greater than the first preset value, the metabolism of microorganisms is slow, and the treatment effect on sewage is poor, by inputting methanol, the acclimation of sludge can be completed in a certain time, and the denitrification rate is improved; when the temperature is less than or equal to the first preset value, the metabolic capacity of microorganisms is vigorous, and there is no need to acclimate the sludge, and sodium acetate is used to have good activity at low temperature and no toxicity.

[0026] Optionally, the total nitrogen sensor 15 is a total nitrogen water quality automatic detector.

[0027] In the prior art, under the condition of high temperature (greater than the first preset value), the denitrifying bacteria have vigorous metabolism and strong activity, and the uptake and utilization rate of carbon source is very fast. After the traditional carbon source is input into the water inlet, because the water will gradually flow to the aerobic zone 12 at the end of the anoxic zone 11, the active microorganisms will consume the carbon source before reaching the aerobic zone 12, resulting in a lack of electron donor (carbon source) in the second half of the anoxic zone 11, and the denitrification reaction cannot be completed. The remaining nitrate (NO3 - ) has no carbon source for reduction, and finally flows out with the effluent, affecting the denitrification efficiency. Under the condition of low temperature (less than or equal to the first preset value), the denitrifying bacteria become lazy, and the activity is significantly reduced, and the metabolic reproduction rate is slow. At this time, the carbon source is input into the water inlet, and the reaction of the microorganisms cannot consume all the carbon source in time, and the unused carbon source will penetrate the anoxic zone 11 and enter the aerobic zone 12. In the aerobic zone 12, the heterotrophic bacteria will preferentially oxidize and decompose these organic matters, consume a large amount of oxygen, increase the aeration energy consumption, more seriously, squeeze the oxygen and space required by the nitrifying bacteria, inhibit the nitrification reaction (ammonia nitrogen oxidation), and cause the entire biological denitrification system to fail. At the same time, the direct effluent of the unused carbon source will cause the effluent COD (chemical oxygen demand) to exceed the standard.

[0028] The sewage treatment method provided by the embodiment, under normal circumstances, sewage flows into the inside from the water inlet end of the anoxic zone 11, flows to the end of the anoxic zone 11, and then enters the aerobic zone 12, and flows out after the reaction in the aerobic zone 12 is completed. The temperature sensor 16 is arranged at the water inlet end of the anoxic zone 11, which can measure the temperature of the water inlet end in real time. The activity of the microorganisms in the anoxic zone 11 is determined by comparing the temperature with the first preset value. When the activity is greater than the first preset value, carbon sources are added at the beginning end and the end of the anoxic zone 11. The carbon source at the beginning end enters the anoxic zone 11 to provide the main energy, and treats most of the nitrate brought by the front-end process. The carbon source at the end treats the residual nitrate, and ensures the thoroughness of denitrification. When the activity is less than or equal to the first preset value, carbon sources are added at the middle end and the end of the anoxic zone 11. The mixed liquid has a preheating and microorganism activation process between the middle ends of the anoxic zone 11, the microorganism concentration in the water is higher, and the activity is relatively stable, so that the carbon source at the middle end can be used faster, the utilization rate is high, the risk of carbon source penetration is reduced, and the carbon source at the end can play a role in bottom protection and fine adjustment, and ensure that the nitrate in the final effluent meets the standard.

[0029] Compared with the prior art, the sewage treatment method provided by the application determines the opening number and position of the dosing valve 21 at the top of the anoxic zone 11 by measuring the temperature of the water inlet, determines the type of carbon source (methanol or sodium acetate) to be added into the anoxic zone 11 according to the temperature of the water inlet and the measurement of the total nitrogen in the water outlet, and simultaneously opens two dosing valves 21, so that the carbon source is available in the entire sewage treatment tank 10 at high temperature, the incomplete denitrification caused by insufficient carbon source is avoided, the total nitrogen concentration in the water outlet is lower and more stable, the carbon source utilization rate is improved at low temperature, the necessary denitrification efficiency is ensured under adverse water temperature conditions, the system is prevented from collapsing due to low temperature, the excessive consumption at the beginning end under high temperature is avoided, the carbon source dosage is not blindly increased for the end, the waste caused by carbon source penetration under low temperature is avoided, the carbon source is allocated and added accurately, and therefore the carbon source medicine cost is saved under the premise of achieving the same denitrification effect, the excessive carbon source is prevented from entering the aerobic zone 12, the oxygen and survival advantage required by nitrifying bacteria are ensured, the effective removal of ammonia nitrogen is ensured, the oxygen consumption of the aerobic zone 12 for decomposing the excess carbon source is reduced, the aeration amount of the fan (for providing oxygen to the aerobic zone 12) can be correspondingly reduced, energy consumption is further saved, the outflow of water COD and TN is effectively controlled to meet the standard, the risk of water quality fluctuation caused by improper carbon source addition is reduced, and the opening position and type of the carbon source are quickly switched by the controller controlling the opening and closing and opening degree of the dosing valve 21 and the electric control valve 31, so that the fluctuation state of the water quality is flexibly coped with, and the sewage treatment effect is ensured.

[0030] In the whole text, high temperature refers to the case that the temperature is greater than the first preset value, and low temperature refers to the case that the temperature is less than or equal to the first preset value.

[0031] In order to ensure the treatment efficiency of sewage, the sealing test of the dosing valve 21, the calibration of the temperature sensor 16, the verification of the performance of the total nitrogen sensor 15 and the corresponding test of the electrically controlled valve 31 of the storage tank 30 can be performed before use.

[0032] As an improved embodiment, the sewage treatment method further comprises a glucose storage tank, the glucose storage tank is provided with an electrically controlled valve 31, a feed pipeline 20 and a dosing valve 21, when the nitrogen value exceeds the second preset value and the reading of the temperature sensor 16 is equal to or greater than the first preset value, the controller determines whether the methanol corresponding storage tank 30 is normal, if normal, the methanol corresponding storage tank 30 is opened, if not normal, the glucose corresponding storage tank 30 is opened.

[0033] In this embodiment, a glucose storage tank is provided, and the opening condition is that the total nitrogen exceeds the second preset value, the water temperature is less than or equal to the first preset value, and the methanol storage tank is abnormal. Glucose, as an easily degradable organic carbon source, is quickly decomposed and utilized by denitrifying bacteria in the anoxic zone 11 after being added to sewage, providing sufficient electron donor for denitrification reaction. When the main carbon source (methanol) cannot be normally supplied, glucose can replace methanol to maintain denitrification reaction, avoid the sudden drop of total nitrogen removal rate due to carbon source terminal, and ensure that the total nitrogen of effluent meets the standard stably.

[0034] It is easily conceivable that the dosing valve 21 on the feed pipeline 20 corresponding to the glucose storage tank also has three, respectively corresponding to the beginning, middle and end of the anoxic zone 11; when which carbon source is used, the dosing valve 21 on the feed pipeline 20 corresponding to the carbon source is opened, and the carbon source flows out from the corresponding storage tank and enters the corresponding feed pipeline 20, which can effectively avoid cross contamination and reaction risk caused by sharing.

[0035] The judgment condition of the methanol storage tank abnormality can be that a pressure sensor is arranged in the methanol storage tank, when the methanol storage tank is opened, if the reading of the internal pressure sensor has no obvious change within 10 minutes, or a liquid level sensor is arranged in the methanol storage tank, when the liquid level sensor detects that the liquid level does not drop after the methanol storage tank is opened, it is judged that the methanol storage tank is abnormal.

[0036] In order to facilitate observation of the abnormal condition of the methanol storage tank, a leakage alarm can be arranged on the methanol storage tank. Correspondingly, a pressure sensor or a liquid level sensor can be arranged in the methanol storage tank, the pressure sensor, the leakage alarm and the liquid level sensor are all connected to the controller, when the methanol storage tank is opened, if the electrical signal transmitted by the pressure sensor to the controller has no obvious fluctuation within a certain period of time (such as 10 minutes), it is determined that the methanol storage tank is abnormal, the controller controls the circuit of the leakage alarm to be connected, and the leakage alarm performs sound and light alarm, which facilitates the operator to check in time.

[0037] Based on the above, in the case of setting methanol storage tank, sodium acetate storage tank, glucose storage tank at the same time, the complete control process of the controller is described: The signal acquisition module comprises a temperature sensor 16 and a total nitrogen sensor 15. The execution terminal comprises an electric control valve 31 and a dosing valve 21, both of which can be electric ball valves. The control terminal comprises a controller.

[0038] The temperature sensor 16 is arranged at the water inlet end of the anoxic zone 11. When the temperature changes, the resistance value changes, and the corresponding electric signal is transmitted to the controller. The controller is internally provided with an analog input module and a digital input module, which can convert the received electric signal into a numerical signal (temperature value) and compare the temperature value with the first preset value set in the internal system. When the conditions for opening the electric control valve 31 or the dosing valve 21 are met in the comparison process, the controller sends instructions to the corresponding electric control valve 31 or dosing valve 21, and the motor of the electric ball valve is powered through the relay driving circuit. The motor rotates forward (valve opening) or reverses (valve closing) through two different signal controls to complete the opening and closing of the electric control valve 31 or the dosing valve 21.

[0039] Alternatively, the electric control valve 31 can also be a pneumatic butterfly valve. In the case of a pneumatic butterfly valve, the controller outputs a signal, and the pneumatic actuator in the pneumatic butterfly valve receives the signal and converts the pneumatic energy into rotary mechanical energy to provide power for opening and closing. The butterfly plate (disc-shaped) rotates around the valve stem to change the "on-off area" with the valve body flow passage to realize opening and closing control.

[0040] As an improved embodiment, when the nitrogen value is equal to or less than the second preset value, it is judged whether the amount of sodium acetate exceeds the third preset value. If it exceeds, the methanol storage tank is switched on. If it does not exceed, the current opening state of the storage tank 30 is maintained. When the amount of sodium acetate exceeds the third preset value, although sodium acetate is easy to degrade, even if the total nitrogen is up to standard, the sodium acetate that is not fully utilized by the anoxic zone 11 denitrifying bacteria may still penetrate into the aerobic zone 12. The heterotrophic bacteria in the aerobic zone 12 will preferentially decompose these excess organic matters. If the decomposition is not complete, it will directly lead to an increase in the chemical oxygen demand of the effluent. In addition, the excess sodium acetate entering the aerobic zone 12 will increase the oxygen consumption of the heterotrophic bacteria, increase the aeration amount of the fan to maintain the dissolved oxygen required for nitrification, and lead to an increase in aeration energy consumption. Therefore, excessive use of sodium acetate will lead to high cost. Under the above conditions, switching to the methanol storage tank can reduce the daily operating cost of wastewater treatment by using the lower range carbon source cost of methanol on the premise of ensuring that the total nitrogen is up to standard.

[0041] It should be noted that the amount of sodium acetate can be determined by two cases: one is to set the metering pump 32 to calculate the amount of sodium acetate, and the other is to set the timer to calculate the use time of sodium acetate.

[0042] As an improved embodiment, when switching from the methanol tank to the sodium acetate tank, the opening degree of the sodium acetate tank gradually increases within a preset time range, and the opening degree of the methanol tank gradually decreases until it is closed. Or, when switching from the sodium acetate tank to the methanol tank, the opening degree of the methanol tank gradually increases within a preset time range, and the opening degree of the sodium acetate tank gradually decreases until it is closed.

[0043] The above transition process is used when the carbon source is initially added to the sewage and when the carbon sources are switched to each other, which can avoid sudden decrease and sudden increase of the carbon source. When the carbon source suddenly decreases, the denitrifying bacteria will stop denitrification due to insufficient donors, and the total nitrogen in the effluent will increase rapidly. When the carbon source suddenly increases, the excess carbon source will penetrate into the aerobic zone 12, causing the oxygen consumption of the heterotrophic bacteria in the aerobic zone 12 to increase rapidly, the aeration energy consumption to rise, and even the survival space of the nitrifying bacteria to be squeezed, causing the ammonia nitrogen removal efficiency to decrease. Gradual transition can ensure the stability of the total carbon source dosage during the switching process, maintain continuous denitrification reaction, and avoid large fluctuations in denitrification efficiency. The degradation difficulty of different carbon sources and the microbial adaptability differ. If the carbon source is not suddenly replaced, the microorganisms need to quickly adjust the metabolic pathway to adapt to the new carbon source, which will cause the microbial activity to decrease temporarily, resulting in temporary weakening of the denitrification ability. The transition process gives the microorganisms a buffer time to adapt to the new carbon source, ensuring that the microbial activity does not decrease sharply, and maintaining the stability of the sludge microbial community structure.

[0044] Among them, the mutual switching of carbon sources includes switching from sodium acetate to methanol, switching from methanol to sodium acetate, and switching from methanol to glucose.

[0045] The transition process can be specifically: the preset time range is 20 minutes, and the proportion of the carbon source corresponding to the tank 30 opened later is increased by 10% every 2 minutes.

[0046] For example, when switching from sodium acetate carbon source to methanol carbon source, the proportion of methanol in all carbon sources in the first 2 minutes is 10%, increased to 20% at the 4th minute, 30% at the 6th minute, 40% at the 8th minute, 50% at the 10th minute, 60% at the 12th minute, 70% at the 14th minute, 80% at the 16th minute, 90% at the 18th minute, and 100% at the 20th minute. Correspondingly, the proportion of sodium acetate in all carbon sources in the first 2 minutes is reduced to 90%, reduced to 80% at the 4th minute, 70% at the 6th minute, 60% at the 8th minute, 50% at the 10th minute, 40% at the 12th minute, 30% at the 14th minute, 20% at the 16th minute, 10% at the 18th minute, and 0 at the 20th minute. The same applies when switching from methanol to sodium acetate or from methanol to glucose.

[0047] As an improved embodiment, the water inlet end of the anoxic zone 11 is provided with a water inlet flow meter 14, and each storage tank 30 is provided with a metering pump 32, and the water inlet flow meter 14 and the metering pump 32 are in communication connection with the controller. When the electric control valve 31 on the storage tank 30 is opened, the metering pump 32 is also opened synchronously, and the carbon source flowing out will form a fixed proportion with the water in the anoxic zone 11, thereby ensuring that the total nitrogen in the effluent meets the standard while saving the use of carbon source and saving cost.

[0048] The water inlet flow meter 14 and the metering pump 32 can also be connected to the controller. The flow meter 14 can adopt an electromagnetic flow meter 14, which is internally provided with an induction coil and an electrode. When sewage flows through the pipeline installed with the flow meter 14, the magnetic field generated by the coil is cut, and according to Faraday's law of electromagnetic induction, the electrode will induce a weak current signal proportional to the flow. After being amplified and filtered by an amplifier and a filter, the current signal is converted into a current signal and transmitted to the controller. The controller connects the circuit connected to the metering pump 32, and the metering pump 32 is opened. The metering pump 32 also calculates the flow of the carbon source (for example, a plunger type metering pump 32) during operation, and transmits the value to the controller. When the controller analyzes that the ratio of carbon source and sewage meets the requirements, the circuit connected to the metering pump 32 is disconnected, and the metering pump 32 is closed.

[0049] Based on the same inventive concept, see Figure 1The embodiment of the present application also provides a multi-carbon source adding system for implementing the above-mentioned sewage treatment method, comprising a sewage treatment tank 10, three adding modules, a carbon source module and a controller. The sewage treatment tank 10 comprises an anoxic zone 11 and an aerobic zone 12 which are in communication with each other. The anoxic zone 11 is provided with an inlet pipe 13 at the beginning end, and the aerobic zone 12 is provided with an outlet pipe at the end. The inlet pipe 13 is provided with an inlet flow meter 14 and a temperature sensor 16, and the outlet pipe is provided with a total nitrogen sensor 15. The adding module is arranged above the anoxic zone 11 and comprises a feeding pipe 20 and three adding valves 21 arranged on the feeding pipe 20. The three adding valves 21 are respectively arranged at the beginning end, the middle end and the end of the anoxic zone 11. The carbon source module comprises three storage tanks 30 corresponding to the adding module. Each storage tank 30 is provided with an electric control valve 31 and a metering pump 32 at the bottom. The controller is used for controlling the opening and closing and the opening degree of the adding valves 21 and the electric control valves 31 and receiving the working parameters of the total nitrogen sensor 15, the temperature sensor 16 and the metering pump 32.

[0050] Compared with the prior art, the multi-carbon source adding system provided by the embodiment can collect sewage treatment parameters (inlet flow, inlet temperature, outlet total nitrogen, etc.) in real time through the communication connection of the controller, the sensor and the flow meter 14. The sensor is directly connected with the controller in communication, replacing manual sampling. Not only the hysteresis of manual detection is avoided, but also the controller can be provided with accurate and continuous original parameters, so that the accurate control of the carbon source adding position, the carbon source type and the carbon source adding amount is ensured. The three storage tanks 30 respectively store methanol, sodium acetate and glucose, and are provided with the electric control valves 31 and the metering pumps 32. The accurate addition of the carbon source can be realized by combining the adding valves 21, and different working conditions and water environments can be flexibly adjusted.

[0051] In some embodiments, a modified embodiment of the above-mentioned sewage treatment tank 10 can adopt a structure as shown in Figure 1 . Referring to Figure 1 , the anoxic zone 11 is provided with a stirrer 40. When sewage enters the anoxic zone 11, the stirrer 40 starts to operate. When there is no carbon source, the operation of the stirrer 40 can realize hydraulic disturbance, ensure the stable denitrification efficiency in the anoxic zone 11 and avoid the deposition of sludge at the bottom of the tank. When the carbon source is added, the stirrer 40 can be used for the rapid mixing of the carbon source and the sewage, so that the added carbon source is rapidly diffused to the whole anoxic zone 11, the uniform distribution of the carbon source concentration in the sewage is ensured, the stable carbon source supply for the denitrifying bacteria is provided, the local enrichment or shortage of the carbon source is avoided, and the efficient denitrification reaction is ensured.

[0052] Optionally, the stirrer 40 can be a submersible stirrer.

[0053] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of sewage treatment, characterised in that, The method comprises the following steps: S10: setting a temperature sensor at the water inlet end of the anoxic zone at the beginning end of the sewage treatment tank; S20: setting a methanol storage tank and a sodium acetate storage tank in communication with the feeding pipe, and each of the storage tanks is provided with an electric control valve and a feeding pipe, and each of the feeding pipes is provided with three dosing valves corresponding to the beginning end, the middle end and the end of the anoxic zone; S30: connecting the electric control valve and the temperature sensor to the controller, and when the temperature exceeds the first preset value, the dosing valves at the beginning end and the end are opened, and when the temperature is less than or equal to the first preset value, the dosing valves at the middle end and the end are opened; S40: setting a total nitrogen sensor at the water outlet pipe of the aerobic zone of the sewage treatment tank, and the total nitrogen sensor is connected to the controller, when the nitrogen value exceeds the second preset value, it is judged whether the reading of the temperature sensor is lower than the first preset value, if lower, the corresponding storage tank of sodium acetate is opened, if equal to or greater than the first preset value, the corresponding storage tank of methanol is opened, when the nitrogen value is equal to or less than the second preset value, the opening state of the current storage tank is maintained.

2. The method of sewage treatment according to claim 1, characterized in that, The method further comprises a glucose storage tank, which is also provided with an electric control valve, a feeding pipe and a dosing valve; When the nitrogen value exceeds the second preset value and the reading of the temperature sensor is equal to or greater than the first preset value, the controller judges whether the corresponding storage tank of methanol is normal, if normal, the corresponding storage tank of methanol is opened, if not normal, the corresponding storage tank of glucose is opened.

3. The method of claim 2, wherein the wastewater is treated in a wastewater treatment plant. The water inlet end of the anoxic zone is provided with a water inlet flowmeter, and each of the storage tanks is provided with a metering pump, and the water inlet flowmeter and the metering pump are in communication connection with the controller.

4. The method of claim 2, wherein the wastewater is treated in a wastewater treatment plant. The methanol storage tank is provided with a leakage alarm.

5. The method of claim 1, wherein the wastewater is treated in a wastewater treatment plant. When the nitrogen value is equal to or less than the second preset value, it is judged whether the amount of sodium acetate exceeds the third preset value, if exceeds, the methanol storage tank is switched on, if does not exceed, the opening state of the current storage tank is maintained.

6. The method of sewage treatment according to claim 1, wherein When switching from the methanol storage tank to the sodium acetate storage tank, the opening degree of the sodium acetate storage tank gradually increases within a preset time range, and the opening degree of the methanol storage tank gradually decreases until it is closed; Or, when switching from the sodium acetate storage tank to the methanol storage tank, the opening degree of the methanol storage tank gradually increases within a preset time range, and the opening degree of the sodium acetate storage tank gradually decreases until it is closed.

7. The method of sewage treatment according to claim 6, characterized in that, The preset time range is 20 minutes, and the proportion of the carbon source corresponding to the storage tank opened later is increased by 10% every 2 minutes.

8. A multi-carbon source dosing system, characterized by, The method comprises the following steps: A sewage treatment tank comprising an anoxic zone and an aerobic zone in communication with each other, the beginning end of the anoxic zone is provided with a water inlet pipe, the end of the aerobic zone is provided with a water outlet pipe, the water inlet pipe is provided with a water inlet flowmeter and a temperature sensor, and the water outlet pipe is provided with a total nitrogen sensor; Three dosing modules are arranged above the anoxic zone, each dosing module comprises a feeding pipe and three dosing valves arranged on the feeding pipe, and the three dosing valves are respectively arranged at the beginning end, the middle end and the end of the anoxic zone; A carbon source module comprising three storage tanks corresponding to the dosing modules one by one, and each of the storage tanks is provided with an electric control valve and a metering pump at the bottom; A controller is arranged to control the opening and closing and opening degree of the dosing valve and the electrically-controlled valve, and receives the total nitrogen sensor, the temperature sensor and the operating indication of the metering pump.

9. The multi-carbon source dosing system of claim 8, wherein, A stirrer is arranged in the anoxic zone.

10. The multi-carbon source dosing system of claim 8, wherein, The electrically-controlled valve is a pneumatic butterfly valve.

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