Method for starting and stably maintaining short-cut nitrification by multi-mode copper ion stress regulation

Abstract

This invention discloses a method for regulating short-range nitrification initiation and stable maintenance under multi-mode copper ion stress, relating to the field of wastewater biological treatment technology. This invention utilizes a multi-mode gradient concentration of Cu... 2+ The activated sludge system was subjected to stress to initiate short-cut nitrification. After experiencing different concentrations of stress, the nitrite accumulation rate in the activated sludge system reached over 80%. Furthermore, using PLC control, a multi-mode Cu was employed during the short-cut nitrification breakdown. 2+ Stress treatment of activated sludge followed by sludge exchange not only maintains a high nitrite accumulation rate in the activated sludge system but also avoids sludge toxicity to a single concentration or a single concentration gradient of Cu. 2+ This invention fosters tolerance and enables stable operation of the short-cut nitrification system. It eliminates the need for controlling harsh environmental conditions to initiate short-cut nitrification, and the addition of Cu is stopped after successful initiation of short-cut nitrification. 2+ The system can still maintain a high nitrite accumulation rate and maintain the stability of short-cut nitrification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage biological treatment, in particular to a method for starting and stably maintaining short-cut nitrification under multi-mode copper ion stress regulation, which is suitable for wastewater treatment fields such as domestic sewage and industrial wastewater. BACKGROUND

[0002] With the continuous development of urbanization and industrialization, the discharge of sewage is gradually increasing, and pollution problems bring great challenges to water environments. Nitrogen-containing pollutants in sewage can cause water eutrophication and other problems, and therefore have attracted widespread attention. Biological denitrification of sewage is widely used. The traditional denitrification process based on nitrification-denitrification has the defects of large aeration quantity and the need for additional carbon source, which increases the operation cost of sewage treatment plants. Compared with the traditional process, the new denitrification process based on short-cut nitrification-anaerobic ammonia oxidation has the advantages of saving 25% of aeration quantity, no need for additional carbon source, and less residual sludge, and is a relatively efficient, low-carbon and economic biological denitrification process.

[0003] The short-cut nitrification-anaerobic ammonia oxidation denitrification process relies on stable short-cut nitrification to provide nitrite nitrogen (NO2 - -N) for anaerobic ammonia oxidation. The core goal is to inhibit nitrite-oxidizing bacteria (NOB) and avoid ammonia nitrogen (NH4 + -N) in sewage being oxidized to NO2 - -N by ammonia-oxidizing bacteria (AOB) and then further oxidized to nitrate nitrogen (NO3 - -N) by NOB, so as to form nitrite accumulation. The difficulty lies in the balance of microorganisms. Maintaining stable short-cut nitrification requires long-term inhibition of the activity of NOB and maintaining the dominant position of AOB. The indicators of municipal sewage such as water temperature, pH and COD are dynamically changing, and NOB in the municipal sewage pipe network will be introduced into the water treatment biological system, so that the activity of AOB is inhibited or the dominant position is difficult to maintain, further leading to the destruction of short-cut nitrification. Therefore, how to maintain stable short-cut nitrification to ensure stable supply of NO2 - -N is a key problem in the application of anaerobic ammonia oxidation.

[0004] The main influencing factors of the current short-cut nitrification method are as follows: (1) Temperature affects the growth rate and metabolic activity of microorganisms, and the optimum temperatures of AOB and NOB are different. Their activities change asynchronously with temperature. AOB has a higher growth rate at a higher temperature (>30 ℃), while NOB is more suitable for a lower temperature (15 ℃~25 ℃). Therefore, controlling the system at a higher temperature can make the growth rate of AOB higher than that of NOB, so as to regulate the formation of short-cut nitrification. However, the temperature of municipal sewage is not stable, and in the low-temperature season, NOB is likely to break through the temperature inhibition, affecting the effect of short-cut nitrification; (2) The oxygen affinity of AOB is lower than that of NOB, and their oxygen saturation constants are 0.2~0.4 mg / L and 1.2~1.5 mg / L, respectively. At a low DO concentration, the activity of NOB will be significantly weakened, so that the growth rate of AOB is greater than that of NOB. Although the low DO concentration will weaken the metabolic activity of microorganisms, the ammonia oxidation of the nitrification process is not significantly affected, so as to realize short-cut nitrification; (3) The optimum pH of AOB and NOB is about 8.0 and about 7.0, respectively. Adding alkali to increase the pH of the system can inhibit the growth of NOB. In addition, under the condition of pH 7.5~8.5, it can promote the dissociation of ammonia nitrogen into free ammonia (FA). When the concentration of free ammonia is higher than 6 mg / L, the activity of NOB can be completely inhibited, but it has a significant effect on AOB. Therefore, increasing the pH can form a double inhibition of pH and FA on NOB, so as to realize short-cut nitrification; (4) Hydroxylamine is an intermediate product of AOB catalyzing ammonia oxidation to nitrite (NH2OH→NO2 - ). Exogenous addition of hydroxylamine can directly enter the metabolic pathway of AOB, accelerate the ammonia oxidation rate, and NOB lacks the metabolic capacity of hydroxylamine and can inhibit its activity. The addition of hydroxylamine can realize short-cut nitrification; (5) Hydrazine can block the nitrite oxidation process of NOB by affecting enzyme activity and interfering with electron transfer, and inhibit the growth of NOB. Low-concentration hydrazine has no inhibition on AOB and can be used as a nitrogen source for AOB. The addition of low-concentration hydrazine can realize short-cut nitrification.

[0005] However, the current short-cut nitrification method still has some defects. Since the water quality indicators of municipal sewage are dynamically changing, in the low-temperature season, NOB may recover its activity and easily break through the inhibition, thereby affecting the effect of short-cut nitrification. Low dissolved oxygen can inhibit NOB, but in the actual reactor, there may be uneven aeration and dissolved oxygen gradient, and NOB may increase in local area. The addition of hydroxylamine and hydrazine can quickly form short-cut nitrification, but long-term use will lead to the resistance of NOB, and the short-cut nitrification will be gradually destroyed. In addition, the short-cut nitrification process needs to inhibit NOB for a long time and maintain stable nitrite accumulation, but how to realize the rapid start-up and stable maintenance of short-cut nitrification is a technical problem to be solved at present. SUMMARY

[0006] The present application aims to provide a method for starting and stably maintaining short-cut nitrification by multi-mode copper ion stress regulation, so as to solve the problems in the prior art. The method can realize short-cut nitrification with high nitrite accumulation rate without harsh conditions, and can automatically perform sludge treatment according to the effluent quality to maintain the stability of short-cut nitrification.

[0007] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0008] One of the technical solutions of the present application is to provide a multi-mode Cu 2+ stress directional regulation method for realizing short-cut nitrification and stable maintenance, wherein the PLC-controlled activated sludge system comprises a short-cut nitrification device and a sludge treatment device in communication.

[0009] The method comprises the following steps.

[0010] (1) Starting of the short-cut nitrification system: in the short-cut nitrification device, the activated sludge with nitrification performance is subjected to multi-mode stress of Cu 2+ with a concentration gradient.

[0011] The concentration gradient Cu 2+ comprises two modes.

[0012] Mode one: the concentration of Cu 2+ increases in a gradient of 1 mg / L, 5 mg / L and 10 mg / L.

[0013] Mode two: the concentration of Cu 2+ decreases in a gradient of 10 mg / L, 5 mg / L and 1 mg / L.

[0014] The gradient concentration of Cu 2+ is sequentially applied by any one of the modes, and when the nitrite accumulation rate in the effluent is greater than or equal to 80% and stable, the addition of Cu 2+ is stopped, and the starting of the short-cut nitrification system is completed.

[0015] (2) Stable maintenance of the short-cut nitrification system: when the nitrite accumulation rate in the water body decreases by 10%, the sludge treatment and exchange are started by the PLC control device:

[0016] A certain proportion of the sludge-water mixture in the short-cut nitrification device is flowed into the sludge treatment device, and the sludge is subjected to stress treatment by using the gradient concentration of Cu 2+ in the mode one or the mode two.

[0017] The treated sludge in the sludge treatment device is returned to the short-cut nitrification device until the nitrite accumulation rate is restored to greater than or equal to 80%.

[0018] As a further preferred embodiment of the present application, in step (2), to avoid the development of tolerance by the activated sludge, if the same mode is used for the first three treatments, the next treatment is automatically switched to another mode.

[0019] As a further preferred embodiment of the present application, the activated sludge is inoculated into the short-cut nitrification device, the dissolved oxygen is controlled to be 4-6 mg / L, and the temperature is controlled to be 23-25℃, and the activated sludge with nitrification performance is obtained when the ammonia nitrogen removal rate is ≥95% in the sequencing batch operation.

[0020] As a further preferred embodiment of the present application, in step (1), the Cu 2+ In the concentration stress stage, Cu 2+ After the effluent water quality is stable (the nitrogen form concentration in the influent and effluent water remains stable), the next gradient concentration is adjusted.

[0021] As a further preferred embodiment of the present application, the sludge treatment device is operated in a sequencing batch mode, and a single treatment cycle comprises: influent, aeration, sedimentation, effluent and idling.

[0022] As a further preferred embodiment of the present application, the PLC-controlled activated sludge system comprises: a raw sewage tank, an influent pump, an aeration device, a short-cut nitrification device, a sludge treatment device, a sludge valve, a dosing device, a sludge return pump, a first effluent valve, a second effluent valve, a water quality detection device, a PLC control device and a temperature control device.

[0023] The raw sewage tank is communicated with the short-cut nitrification device through the influent pump, and the short-cut nitrification device is provided with the aeration device, the water quality detection device, the temperature control device and the first effluent valve; the bottom of the short-cut nitrification device is communicated with the sludge treatment device through the sludge valve, and the sludge treatment device is further communicated with the short-cut nitrification device through the sludge return pump; the sludge treatment device is provided with the second effluent valve; the dosing device is communicated with the short-cut nitrification device and the sludge treatment device; and the influent pump, the aeration device, the temperature control device, the water quality detection device, the sludge valve, the first effluent valve, the dosing device, the sludge return pump, the first effluent valve and the second effluent valve are connected with the PLC control device.

[0024] In the present application, the second effluent valve can be connected with a subsequent anaerobic ammonia oxidation process link.

[0025] Further, the sewage is added to the short-cut nitrification device so that the sludge concentration is 4500 mg / L.

[0026] Further, the short-cut nitrification device is operated in batch mode, and a sludge treatment cycle includes 10 min of sludge feeding, 180 min of stirring, 30 min of standing, 10 min of water draining, and 10 min of idling.

[0027] The sludge treatment device is operated in batch mode, and a sludge treatment cycle includes 10 min of sludge feeding, 180 min of stirring, 30 min of standing, 10 min of water draining, and 10 min of idling.

[0028] More specifically, the present application includes the following strategies:

[0029] a. obtaining activated sludge with good nitrification performance:

[0030] The collected activated sludge is inoculated in the short-cut nitrification device, and synthetic sewage is fed into the short-cut nitrification device from a sewage raw water tank through a water feeding pump at a water draining ratio of 60%, and the sludge concentration (MLSS) is controlled to be about 4500 mg / L.

[0031] After the water feeding is completed, the aeration pump is started, the DO in the short-cut nitrification device is controlled to be 4-6 mg / L through a gas flow meter, and the temperature control device is started to control the temperature to be 23-25℃.

[0032] The short-cut nitrification device is operated in batch mode, and the hydraulic retention time (HRT) is 3 h, and there are 4 cycles per day, each cycle including 10 min of water feeding, 200 min of aeration, 30 min of sedimentation, 10 min of water draining, and 110 min of idling. 20 min before the end of aeration, the water quality in the short-cut nitrification device is detected by using a water quality detection device. When the ammonia nitrogen removal rate is above 95% and stable, activated sludge with good nitrification performance is obtained.

[0033] b. multi-mode Cu 2+ Stress-oriented regulation of sludge to obtain short-cut nitrification function:

[0034] In the present application, after the performance of the activated sludge is restored and stabilized, the short-cut nitrification device is maintained in batch mode, and gradient concentrations of Cu 2+ Stress the activated sludge system, and use the response difference of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to Cu 2+ to realize short-cut nitrification.

[0035] In the present application, gradient concentrations of Cu 2+ Stress modes include two kinds: concentration gradient increasing mode and concentration gradient decreasing mode. Either mode can be used to stress the activated sludge system.

[0036] The specific starting Cu 2+ concentration in any mode 2+ , the effluent water quality is detected by the water quality detection device, and according to the effluent water quality detection result, when the performance of the short-cut nitrification device is stable (the concentration of various forms of nitrogen in the influent and effluent remains stable), the Cu 2+ concentration is adjusted to the next Cu 2+ concentration in the mode.

[0037] Before and after the Cu 2+ concentration changes, the NH4 + -N, NO2 - -N and NO3 - -N concentrations in the water body in the short-cut nitrification device are measured throughout the cycle, and the NH4 + -N, NO2 - -N and NO3 - -N concentrations in the influent and effluent are measured in other cycles. When the nitrite accumulation rate is ≥80%, the directional regulation of activated sludge is completed, and the sludge obtains short-cut nitrification function, and Cu 2+ is not added to the short-cut nitrification device thereafter. The nitrite accumulation rate is the proportion of nitrite nitrogen concentration in the effluent to the total nitrogen concentration.

[0038] According to the water quality detection, when the nitrite accumulation rate is ≥80% and remains stable, it is considered that the sludge has obtained short-cut nitrification function.

[0039] c. Multi-mode Cu 2+ stress directional regulation and maintenance strategy

[0040] Multi-mode Cu 2+ stress directional regulation and maintenance of short-cut nitrification is controlled by a PLC control device, which uses multi-mode concentration gradient Cu 2+ to treat activated sludge, and performs sludge exchange on the short-cut nitrification device and the sludge treatment device to maintain stable short-cut nitrification. The Cu 2+ concentration mode of sludge treatment is selected by the PLC control device from mode one and mode two, in order to avoid the activated sludge adapting to one Cu 2+ concentration mode, when the same Cu 2+ concentration mode is used for the current three times of sludge treatment, the PLC control device selects another Cu 2+ concentration mode for the next time of sludge treatment.

[0041] The short-cut nitrification device is maintained in a sequencing batch operation, and 10 minutes before the aeration of the short-cut nitrification device ends, the sludge valve is opened, and a certain proportion of sludge-water mixture flows into the sludge treatment device. Different modes of gradient concentration Cu2+ Stress activated sludge, through dosing device to sludge treatment device with 60% of the drainage ratio to add Cu 2+ Liquid medicine, after dosing, control the stirring device stirring, after stirring, control the second drainage valve drainage. Sludge treatment device adopts sequence batch operation, in a sludge treatment period, water inlet 10 min, stirring 180 min, standing 30 min, drainage 10 min, idle 10 min. When completing a sludge treatment, 10 min before aeration of short path nitrification device, control sludge reflux pump to return the activated sludge to short path nitrification device.

[0042] When the nitrite accumulation rate fed back by the water quality detection device in the short path nitrification device decreases by 10%, start sludge exchange and sludge treatment under the control of PLC control device until the nitrite accumulation rate is greater than or equal to 80%.

[0043] The present application discloses the following technical effects:

[0044] (1) The present application can provide stable nitrite nitrogen for anaerobic ammonia oxidation process of municipal wastewater;

[0045] (2) The present application does not need to accurately control parameters such as aeration amount, pH, aeration time, etc., and can still maintain stable short path nitrification even under the condition of higher dissolved oxygen, avoiding problems such as sludge bulking caused by low dissolved oxygen;

[0046] (3) The present application does not need to control harsh environmental conditions to start short path nitrification, is easy to realize, and after successfully starting short path nitrification, stop adding Cu 2+ , the system can still maintain a high nitrite accumulation rate;

[0047] (4) The present application can automatically perform sludge treatment according to the feedback of nitrite accumulation rate to maintain the short path nitrification function of activated sludge. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0049] Figure 1The structural schematic diagram of the device used in the present application; wherein: 1-wastewater raw water tank, 2-water inlet pump, 3-aeration pump, 4-gas flow meter, 5-aeration head, 6-short-range nitrification device, 7-sludge valve, 8-dosing device, 9-sludge return pump, 10-stirrer, 11-sludge treatment device, 12-first water outlet valve, 13-second water outlet valve, 14-water quality detection device, 15-PLC control device, 16-temperature control device.

[0050] Figure 2 The change curve diagram of nitrite nitrogen, nitrate nitrogen and nitrite accumulation rate of effluent of the activated sludge system after the mode one regulation and control is adopted in the embodiment 1 of the present application;

[0051] Figure 3 The full cycle concentration change diagram of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen of the activated sludge system before (a) and after (b) the mode one regulation and control is adopted in the embodiment 1 of the present application;

[0052] Figure 4 The change curve diagram of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and nitrite accumulation rate of effluent of the activated sludge system after the mode two regulation and control is adopted in the embodiment 2 of the present application;

[0053] Figure 5 The full cycle concentration change diagram of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen of the activated sludge system before (a) and after (b) the mode two regulation and control is adopted in the embodiment 2 of the present application. DETAILED DESCRIPTION

[0054] The various illustrative embodiments of the present application will now be described in detail in connection with the accompanying drawings. This description is made for the purpose of demonstrating certain aspects of the present application and should not be taken as limiting the present application. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0055] It should be understood that the terms used in the present application are merely used to describe particular embodiments and are not intended to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range, and any other stated value or intermediate value in the stated range, is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0056] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In case of conflict, the content of the present specification will control.

[0057] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the application. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0058] As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having”, and the like are open-ended terms that are intended to denote the inclusion of elements or steps without excluding other elements or steps.

[0059] It should be noted that the present application does not describe in detail the conventional operation means in the art, and is not the focus of the present application.

[0060] The activated sludge used in the embodiments of the present application is collected from the aeration tank of a municipal sewage treatment plant; the sewage used is synthetic sewage, and the ammonia nitrogen concentration thereof is 30-35 mg / L, and the chemical oxygen demand (COD) concentration is 270-300 mg / L.

[0061] The structural schematic diagram of the device used in the embodiments of the present application is as shown in Figure 1 The structural schematic diagram of the device used in the embodiments of the present application is as shown in

[0062] 1-wastewater raw water tank, 2-water inlet pump, 3-aeration pump, 4-gas flow meter, 5-aeration head, 6-short-cut nitrification device, 7-sludge valve, 8-dosing device, 9-sludge return pump, 10-agitator, 11-sludge treatment device, 12-first water outlet valve, 13-second water outlet valve, 14-water quality detection device, 15-PLC control device, 16-temperature control device.

[0063] The wastewater raw water tank 1 is connected with the short-cut nitrification device 6 via the water inlet pump 2, and the aeration pump 3 is connected with the aeration head 5 at the bottom of the short-cut nitrification device 6 via the gas flow meter 4;

[0064] The short-cut nitrification device 6 is provided with the water quality detection device 14 and the temperature control device 16, and is also provided with the first water outlet valve 12 and the sludge valve 7, and the sludge valve 7 is connected with the sludge treatment device 11 through a pipeline;

[0065] The sludge treatment device 11 is provided with the second water outlet valve 13 and the agitator 10;

[0066] The sludge treatment device 11 is connected with the short-cut nitrification device 6 via the sludge backflow pump 9;

[0067] The dosing device 8 is connected with the short-cut nitrification device 6 and the sludge treatment device 11 simultaneously.

[0068] The water inlet pump 2, the aeration pump 3, the temperature control device 16, the water quality detection device 14, the sludge valve 7, the first water outlet valve 12, the dosing device 8, the agitator 10, the sludge backflow pump 9, and the second water outlet valve 13 are connected with the PLC control device 15 respectively.

[0069] Example 1

[0070] A multi-mode Cu 2+ The method for realizing short-cut nitrification and stably maintaining by stress directional regulation:

[0071] a. Obtain activated sludge with good nitrification performance:

[0072] The collected activated sludge is inoculated in the short-cut nitrification device 6, and the synthetic sewage from the sewage raw water tank 1 enters the short-cut nitrification device 6 through the water inlet pump 2 according to a drainage ratio of 60%, and the sludge concentration (MLSS) is controlled to be about 4500 mg / L.

[0073] After the water inlet is completed, the aeration pump 3 is started, the DO in the short-cut nitrification device 6 is controlled to be 4-6 mg / L through the gas flow meter 4, and the temperature control device 16 is started to control the temperature to be 23-25℃.

[0074] The short-cut nitrification device 6 adopts sequencing batch operation, the hydraulic retention time (HRT) is 3 h, there are 4 cycles per day, in each cycle, the water inlet is 10 min, the aeration is 200 min, the sedimentation is 30 min, the water outlet is 10 min, and the idle is 110 min. 20 min before the end of the aeration, the water quality in the short-cut nitrification device 6 is detected by using the water quality detection device 14. When the ammonia nitrogen removal rate is ≥95% and is stable, the activated sludge with good nitrification performance is obtained.

[0075] b. Multi-mode Cu 2+ Obtain short-cut nitrification function by stress directional regulation of sludge:

[0076] Obtain activated sludge with good nitrification performance, adopt gradient concentration Cu 2+ Stress (mode one) activated sludge system, utilize the response difference of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to Cu 2+ to realize short-cut nitrification.

[0077] In the starting Cu2+ Concentration, short-range nitrification device 6 into the water at the same time, by adding device 8 to short-range nitrification device 6 Cu 2+ , using water quality detection device 14 to detect effluent water quality, according to the effluent water quality test results, when the performance of short-range nitrification device 6 is stable, adjust Cu 2+ Concentration is the next Cu 2+ Concentration.

[0078] Before and after the period of Cu 2+ Concentration change, the NH4 + -N, NO2 - -N and NO3 - -N concentration in the short-range nitrification device 6 water body, other periods only measure the NH4 + -N, NO2 - -N and NO3 - -N concentration. According to the water quality detection, when the nitrite accumulation rate is greater than or equal to 80%, the directional control of activated sludge is completed, and the sludge obtains short-range nitrification function. After that, no Cu 2+ .

[0079] c. Multi-mode Cu 2+ Stress directional control maintenance strategy

[0080] Multi-mode stress directional control of short-range nitrification is controlled by PLC control device 15, which uses multi-mode concentration gradient Cu 2+ to treat activated sludge, and the sludge exchange is carried out in short-range nitrification device 6 and sludge treatment device 11, so as to maintain stable short-range nitrification.

[0081] To avoid the activated sludge adapting to a Cu 2+ Concentration mode, the first three times of sludge treatment all use the same Cu 2+ Concentration mode (mode one), the next time of sludge treatment, PLC control device 15 selects another Cu 2+ Concentration mode (mode two).

[0082] Before the aeration of short-range nitrification device 6 ends for 10 min, open the sludge valve 7, and a certain proportion of sludge-water mixture flows into the sludge treatment device 11. Using different modes of gradient concentration Cu 2+ Stress activated sludge, through adding device 8 to add Cu 2+The liquid medicine is added, and the stirring device 10 is controlled to stir after the addition of the medicine is completed. The second drain valve 13 is controlled to drain after the stirring is completed. The sludge treatment device 11 adopts a sequencing batch operation. In one sludge treatment period, water is fed for 10 minutes, stirring is performed for 180 minutes, standing is performed for 30 minutes, water is drained for 10 minutes, and idling is performed for 10 minutes. When one sludge treatment is completed, the treated activated sludge is returned to the short-cut nitrification device 6 by controlling the sludge return pump 9 before the aeration of the short-cut nitrification device 6 is completed.

[0083] Example 2

[0084] A multi-mode Cu 2+ The method for realizing short-cut nitrification and stably maintaining by stress directional regulation:

[0085] a. Obtain activated sludge with good nitrification performance:

[0086] The collected activated sludge is inoculated in the short-cut nitrification device 6. The synthetic sewage is fed into the short-cut nitrification device 6 from the sewage raw water tank 1 through the water feeding pump 2 according to a drainage ratio of 60%, and the sludge concentration (MLSS) is controlled to be about 4500 mg / L.

[0087] After the water feeding is completed, the aeration pump 3 is started, the DO in the short-cut nitrification device 6 is controlled to be 4-6 mg / L through the gas flow meter 4, and the temperature control device 16 is started to control the temperature to be 23-25℃.

[0088] The short-cut nitrification device 6 adopts a sequencing batch operation, the hydraulic retention time (HRT) is 3 hours, there are 4 cycles per day, in each cycle, water is fed for 10 minutes, aeration is performed for 200 minutes, sedimentation is performed for 30 minutes, water is drained for 10 minutes, and idling is performed for 110 minutes. The water quality in the short-cut nitrification device 6 is detected by using the water quality detection device 14 before the aeration is completed for 20 minutes. When water is drained, the first drain valve 12 is opened to drain. According to the water quality detection result, when the ammonia nitrogen removal rate is greater than or equal to 95% and is stable, it is considered that the activated sludge performance is recovered and stable.

[0089] b. Multi-mode Cu 2+ Obtain short-cut nitrification function by stress directional regulation of sludge:

[0090] After the activated sludge with good nitrification performance is obtained, the gradient concentration Cu 2+ stress (mode two) activated sludge system is used to realize short-cut nitrification by using the response difference of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) to Cu 2+ .

[0091] Under the initial Cu 2+ concentration of mode two, Cu is added to the short-cut nitrification device 6 by using the dosing device 8 while water is fed into the short-cut nitrification device 6.2+ The water quality is detected by the water quality detection device 14. After the performance of the short-cut nitrification device 6 is stable, the Cu 2+ concentration is adjusted according to the detection result of the effluent water quality. 2+ concentration.

[0092] The NH4 2+ -N, NO2 + -N and NO3 - -N concentrations in the short-cut nitrification device 6 are measured during the period before and after the change of the Cu - concentration. The NH4 + -N, NO2 - -N and NO3 - -N concentrations in the influent and effluent are measured during other periods. When the nitrite accumulation rate is greater than or equal to 80%, the directional regulation of the activated sludge is completed, and the Cu 2+ is no longer added to the short-cut nitrification device 6.

[0093] c. Multi-mode Cu 2+ stress directional regulation maintenance strategy

[0094] The multi-mode Cu 2+ stress directional regulation is used to maintain the short-cut nitrification by the PLC control device 15. The activated sludge is treated by using the multi-mode Cu 2+ stress, and the sludge exchange is performed on the short-cut nitrification device 6 and the sludge treatment device 11, so as to maintain the stable short-cut nitrification.

[0095] To avoid the adaptation of the activated sludge to one Cu 2+ concentration mode, the same Cu 2+ concentration mode (mode two) is used for the first three times of sludge treatment, and another Cu 2+ concentration mode (mode one) is selected by the PLC control device 15 for the next sludge treatment.

[0096] Before the aeration of the short-cut nitrification device 6 is completed for 10 minutes, the sludge valve 7 is opened, and a certain proportion of the sludge-water mixture flows into the sludge treatment device 11. The activated sludge is stressed by using different modes of gradient Cu 2+ concentration, and the Cu 2+When the concentration reaches the set value, the dosing is completed, the stirring device 10 is controlled to stir, and after the stirring is completed, the second drain valve 13 is controlled to drain after a period of standing. The sludge treatment device 11 is operated in a sequencing batch mode, in which, in one sludge treatment cycle, water is fed for 10 min, stirring is performed for 180 min, standing is performed for 30 min, water is drained for 10 min, and the device is idle for 10 min. When one sludge treatment is completed, 10 min before the aeration of the short-cut nitrification device 6 is completed, the sludge reflux pump 9 is controlled to reflux the treated activated sludge to the short-cut nitrification device 6.

[0097] Figure 2 The change curve diagram of nitrite nitrogen, nitrate nitrogen and nitrite accumulation rate of effluent of the activated sludge system after the mode one is adopted to regulate in the embodiment 1 of the application is shown in the following figure;

[0098] Figure 3 The full-cycle concentration change diagram of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen of the activated sludge system before (a) and after (b) the mode one is adopted to regulate in the embodiment 1 of the application is shown in the following figure;

[0099] Figure 4 The change curve diagram of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and nitrite accumulation rate of effluent of the activated sludge system after the mode two is adopted to regulate in the embodiment 2 of the application is shown in the following figure;

[0100] Figure 5 The full-cycle concentration change diagram of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen of the activated sludge system before (a) and after (b) the mode two is adopted to regulate in the embodiment 2 of the application is shown in the following figure.

[0101] From the figures of Figure 2 and Figure 4 , it can be seen that the two embodiments use different modes to start the short-cut nitrification, and even if the inhibition of Cu ions is removed, the nitrite accumulation rate of the effluent of the system can be maintained at a high level.

[0102] From the figures of Figure 3 and Figure 5 , it can be seen that the similarities and differences of the full-cycle performance before and after the start of the short-cut nitrification in the two embodiments, and after the start, the nitrogen in the effluent is mainly in the form of nitrite.

[0103] The above-described embodiments only describe the preferred modes of the application, and do not limit the scope of the application. Without departing from the design spirit of the application, various modifications and improvements to the technical solutions of the application made by those skilled in the art shall fall within the protection scope determined by the claims of the application.

Claims

1. A multi-modal Cu 2+ The method for stress-oriented regulation to achieve short-range nitrification and stable maintenance is characterized in that, The PLC-controlled activated sludge system comprises a short-cut nitrification device and a sludge treatment device in communication; The method comprises the following steps: (1) Start-up of a short-cut nitrification system: in the short-cut nitrification device, a concentration gradient of Cu 2+ was applied to activated sludge having nitrification performance as a multi-mode stress; The concentration gradient Cu 2+ Includes two modes: Mode one: Cu 2+ The concentration is increased by 1 mg / L, 5 mg / L, 10 mg / L gradient; Mode two: Cu 2+ The concentration is decreased by 10 mg / L, 5 mg / L, 1 mg / L gradient; Sequentially applying gradient concentration Cu by any mode 2+ When the accumulation rate of nitrite in effluent is ≥80% and stable, stop adding Cu 2+ Complete the start-up of the short-cut nitrification system; (2) Stable maintenance of the short-cut nitrification system: when the nitrite accumulation rate in the water body decreases by 10%, the sludge treatment and exchange are started by the PLC control device: passing a portion of the sludge mixture within the short-cut nitrification device to the sludge treatment device, employing the gradient concentration Cu of mode one or mode two 2+ stressed sludge; The treated sludge in the sludge treatment device is returned to the short-cut nitrification device until the nitrite accumulation rate is restored to ≥80%.

2. The method of claim 1, wherein, In step (2), to avoid the tolerance of activated sludge, if the same mode is used for the first three treatments, the next treatment is automatically switched to another mode.

3. The method of claim 1, wherein, The activated sludge is inoculated into the short-cut nitrification device, the dissolved oxygen is controlled at 4-6 mg / L, the temperature is controlled at 23-25℃, and the system is operated in a sequencing batch mode; when the ammonia nitrogen removal rate is ≥95%, the activated sludge with nitrification performance is obtained.

4. The method of claim 1, wherein, In step (1), in a single Cu 2+ Concentration stress phase, synchronously add Cu 2+ , after the effluent water quality is stable, adjust to the next gradient concentration.

5. The method of claim 1, wherein, The PLC-controlled activated sludge system comprises a sewage raw water tank, a water inlet pump, an aeration device, a short-cut nitrification device, a sludge treatment device, a sludge valve, a dosing device, a sludge return pump, a first drainage valve, a second drainage valve, a water quality detection device, a PLC control device, and a temperature control device; The sewage raw water tank is in communication with the short-cut nitrification device through the water inlet pump, and the short-cut nitrification device is provided with the aeration device, the water quality detection device, the temperature control device, and the first drainage valve; the bottom of the short-cut nitrification device is in communication with the sludge treatment device through the sludge valve, and the sludge treatment device is also in communication with the short-cut nitrification device through the sludge return pump; the sludge treatment device is provided with the second drainage valve; the dosing device is in communication with the short-cut nitrification device and the sludge treatment device; and the water inlet pump, the aeration device, the temperature control device, the water quality detection device, the sludge valve, the first drainage valve, the dosing device, the sludge return pump, the first drainage valve, and the second drainage valve are connected with the PLC control device.

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