Nitrification enhancement process for low temperature denitrification

Abstract

The application discloses a nitrification enhancement method for low-temperature denitrification, which comprises the following steps: preparing a nitrification sludge culture unit, adding biochemical system sludge as inoculation sludge to an aerobic tank, mixing biochemical influent and ammonia-containing wastewater uniformly in a regulating tank, and then sending the mixed water to an anoxic tank and the aerobic tank, carrying out intermittent water culture, starting continuous water culture when the nitrification rate reaches 13-20 mg / (L.h), and periodically adding the obtained nitrification sludge to a biochemical denitrification system for low-temperature denitrification. The method has low cost, can efficiently culture nitrification sludge, and guarantees the normal operation of the biochemical denitrification system under low-temperature conditions in winter through nitrification enhancement.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment and relates to a nitrification enhancement method for low-temperature denitrification. Background Art

[0002] For traditional biochemical denitrification processes, low temperatures significantly inhibit the growth rate of autotrophic nitrifying bacteria and the activity of their own enzymes, reducing the efficiency of ammonia nitrogen removal. The normal growth temperature of most nitrifying bacteria is 20℃ to 35℃. Low temperatures have a significant impact on the activity of enzymes within microbial cells. In winter, when the water temperature is below 19℃, measures such as extending the acclimation time of nitrifying bacteria and increasing the hydraulic retention time of the biochemical system are needed to ensure the normal operation of the nitrification system. When the water temperature is below 16℃, the nitrification activity and efficiency drop significantly, and the nitrification system cannot operate normally, resulting in abnormal denitrification function of the biochemical station and excessive NH3-N and TN in the effluent of the biochemical station.

[0003] Although there are many measures such as heating and heat preservation, adding nitrifying bacteria, and increasing sludge concentration that can be used to ensure the nitrification function of the biochemical system under low-temperature conditions, the above measures also have many shortcomings: (1) Heating and heat preservation of sewage, on the one hand, increases energy consumption and greatly increases the cost of sewage treatment; on the other hand, due to the large steam consumption and supply shortage in winter, it may be impossible to heat the water to a suitable temperature; (2) The commercially available nitrifying bacteria are relatively single, expensive, have poor environmental compatibility, and slow to take effect. Adding nitrifying bacteria cannot guarantee the long-term stability of the nitrification function of the biochemical system; (3) The proportion of nitrifying bacteria in ordinary biochemical sludge is low. Increasing the sludge concentration will only increase the number of nitrifying bacteria to a limited extent, and significantly increasing the sludge concentration of the system will increase the load of the subsequent sludge filter press system. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a low-cost, efficient cultivation of nitrifying sludge, and a nitrification enhancement method for low-temperature denitrification that ensures the normal operation of the biochemical denitrification system under low temperature conditions in winter through nitrification enhancement.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0006] A nitrification enhancement method for low-temperature denitrification comprises the following steps:

[0007] (1) Inoculating sludge: Prepare a nitrifying sludge cultivation unit, which includes a regulating tank, an anoxic tank, and an aerobic tank connected in sequence; add biochemical system sludge with a total nitrogen removal rate of 60% to 80% as inoculating sludge to the aerobic tank, stirring and aerating while adding;

[0008] (2) Intermittent water inflow cultivation: biochemical inflow and ammonia-containing wastewater are sent to the regulating tank, the carbon-nitrogen ratio of the biochemical inflow is 8-15, and the ammonia nitrogen concentration of the ammonia-containing wastewater is 300mg / L-10000mg / L. After mixing, the ammonia nitrogen concentration of the inflow is controlled to be 100mg / L-200mg / L, the carbon-nitrogen ratio is 2-5, and the pH value is adjusted to 7.5-8.5 to obtain nitrified inflow. The nitrified inflow is sent from the regulating tank to the anoxic tank, the dissolved oxygen in the anoxic tank is controlled to be 0.15mg / L-0.35mg / L, and denitrification reaction is carried out in the anoxic tank. The effluent from the anoxic tank flows into the aerobic tank, the dissolved oxygen in the aerobic tank is controlled to be 1.5mg / L-8mg / L, and the pH value is adjusted to 7.0-8.5. Nitrification reaction is carried out in the aerobic tank, and the water is drained after the nitrification reaction. After drainage, the above-mentioned water inflow to drainage operation is repeated to carry out intermittent water inflow cultivation;

[0009] (3) Continuous water inlet culture: When the nitrification rate of the intermittent water inlet culture reaches 13 mg / (L·h) to 20 mg / (L·h), continuous water inlet culture is started, the ammonia nitrogen concentration of the inlet water in the regulating tank is controlled to be 200 mg / L to 500 mg / L, the carbon-nitrogen ratio is 2 to 5, the dissolved oxygen in the anoxic tank is controlled to be 0.10 mg / L to 0.35 mg / L, and denitrification reaction is carried out in the anoxic tank, the dissolved oxygen in the aerobic tank is controlled to be 1.5 mg / L to 8 mg / L, and the pH value is 7.0 to 8.5, and nitrification reaction is carried out in the aerobic tank to obtain nitrified sludge;

[0010] (4) Low-temperature denitrification: When the biochemical denitrification system is operated at a low temperature, the low temperature is 13°C to 19°C, and the nitrified sludge obtained from the aerobic tank in step (3) is periodically added to the biochemical denitrification system, so that the nitrification rate of the biochemical system when operating at a low temperature is greater than 2 mg / (L·h), thereby achieving nitrification enhancement of low-temperature denitrification.

[0011] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, the time for the intermittent water infusion culture in step (3) to reach the nitrification rate is 15 to 60 days.

[0012] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, in step (3), the hydraulic retention time of the continuous water inlet culture is 10 hours to 48 hours.

[0013] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, in step (4), the time for periodically adding nitrifying sludge is 1 to 30 days, and the amount of periodically added nitrifying sludge each time is 1% to 10% of the volume of the biochemical denitrification system.

[0014] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, the sludge concentration in the aerobic tank is controlled to be 2500 mg / L to 6500 mg / L during both the intermittent water inlet culture and the continuous water inlet culture.

[0015] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, in step (2), each time water is intermittently added for cultivation, the water addition time is 1 hour to 2 hours, the hydraulic retention time is 10 hours to 24 hours, and the drainage time is 1 hour to 2 hours.

[0016] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, in step (2), the ammonia-containing wastewater is one or more of the ammonia-containing wastewater from the biochemical station filter press, the ammonia-containing wastewater from the power plant, and the ammonia-containing wastewater from the production workshop.

[0017] The above-mentioned nitrification enhancement method for low-temperature denitrification is preferably provided with an agitator or a plug flow reactor in the anoxic tank, and an agitator or a plug flow reactor in the aerobic tank. The aerobic tank is also provided with an online monitoring device, and the online monitoring device includes an aeration device, a pH probe, a dissolved oxygen probe and a temperature probe. The aerobic tank is connected to the anoxic tank through a nitrification liquid reflux pipe.

[0018] In the above-mentioned nitrification enhancement method for low-temperature denitrification, preferably, in steps (2) and (3), part of the nitrified liquid produced in the aerobic tank is refluxed to the anoxic tank through the nitrified liquid reflux pipe, and the amount of the part of the nitrified liquid is 200% to 300% of the water inlet flow rate.

[0019] Explanation of terms in this invention:

[0020] Hydraulic retention time refers to the average residence time of sewage in the biochemical system, that is, the ratio of the biochemical system pool capacity to the inlet flow rate.

[0021] A2O refers to the anaerobic-anoxic-aerobic process.

[0022] A / O refers to the anoxic-aerobic denitrification process.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] (1) The method of the present invention uses the return sludge of the biochemical station or the sludge of the thickening tank as the inoculated sludge to cultivate nitrifying sludge, thereby retaining the biodiversity of the sludge itself, having good biocompatibility and low cultivation cost.

[0025] This method employs intermittent water infusion followed by continuous water infusion, significantly shortening the incubation time for nitrifying sludge. The simple apparatus and operation facilitate engineering applications. Compared to gradient incubation methods that gradually increase the ammonia nitrogen content in the influent, this method directly incubates at appropriate ammonia nitrogen concentrations, which neither inhibits nitrifying sludge nor accelerates the incubation process.

[0026] The method of the present invention can cultivate nitrifying sludge at low cost and high efficiency, increase the proportion of nitrifying bacteria in the biochemical system by adding nitrifying sludge, and ensure the normal operation of the nitrification system under low temperature conditions in winter through nitrification enhancement technology.

[0027] (2) The influent for cultivating nitrifying sludge in the present invention is the influent of the factory biochemical station, the filter press wastewater of the biochemical station, the ammonia nitrogen-containing wastewater of the factory power workshop, and the triethylamine and di-n-butylamine wastewater of the production workshop, etc., rather than artificially prepared nutrient solution. This is closer to engineering practice, and the cultivated nitrifying sludge has better environmental compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a process flow chart of the nitrification enhancement method for low-temperature denitrification in Examples 1 to 3 of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby. The materials and instruments used in the following examples are all commercially available.

[0030] Example 1

[0031] A nitrification enhancement method for low-temperature denitrification of the present invention, such as Figure 1 As shown, the following steps are included:

[0032] (1) Inoculating sludge: Prepare a nitrifying sludge culture unit, which includes a regulating tank, an anoxic tank and an aerobic tank connected in sequence. Both the anoxic tank and the aerobic tank are equipped with a plug flow reactor. The aerobic tank is also equipped with an online monitoring device, which includes an aeration device, a pH probe, a dissolved oxygen probe and a temperature probe. The aerobic tank is also connected to the anoxic tank through a nitrification liquid return pipe.

[0033] While the aerobic tank is being stirred and aerated, the biochemical system sludge (specifically the sludge from the biochemical station concentration tank) with a total nitrogen removal rate of 70% is added to the aerobic tank as inoculated sludge. During subsequent intermittent water inlet culture and continuous water inlet culture, the sludge concentration in the aerobic tank is controlled to be 3500 mg / L.

[0034] (2) Intermittent water inlet cultivation: send the biochemical inlet water and ammonia-containing wastewater into the regulating tank, the carbon-nitrogen ratio of the biochemical inlet water is 10, the ammonia nitrogen concentration is 55 mg / L, and the ammonia nitrogen concentration of the ammonia-containing wastewater is 8000 mg / L. The ammonia-containing wastewater uses the ammonia-containing wastewater of the power plant, the ammonia-containing wastewater of the production workshop or the ammonia-containing wastewater filtered by the biochemical station. The biochemical inlet water and the ammonia-containing wastewater are mixed evenly, and the ammonia nitrogen concentration of the inlet water is controlled to be 100 mg / L and the carbon-nitrogen ratio is 5. The pH value is adjusted to 8.5. The ammonia water of the power plant or the alkali of the workshop waste liquid can be used to adjust the pH value to obtain nitrified inlet water. The nitrification influent is sent from the regulating tank to the anoxic tank, where the dissolved oxygen level is controlled at 0.15mg / L to 0.35mg / L. Denitrification occurs in the anoxic tank. The effluent from the anoxic tank flows into the aerobic tank, where the dissolved oxygen level is controlled at 3mg / L to 5mg / L and the pH is adjusted to 7.0 to 8.5. Nitrification occurs in the aerobic tank, and the water is drained after nitrification. After drainage, the above water inlet and draining operations are repeated for intermittent water infusion. Each intermittent water infusion infusion has a water inflow time of 1 hour, a hydraulic retention time of 24 hours, and a draining time of 2 hours. In the aerobic tank, a portion of the nitrified liquid (containing nitrate nitrogen) is returned to the anoxic tank through the nitrification liquid return pipe. The amount of refluxed nitrified liquid is 200% of the inlet flow rate.

[0035] In this step, the ammonia-containing wastewater can provide ammonia nitrogen for cultivating nitrifying sludge and reduce the carbon-nitrogen ratio of the influent of the regulating tank. The cultivation of nitrifying sludge generally requires less carbon source, but in order to ensure a better settling ratio and growth rate of the nitrifying sludge and prevent the loss of nitrifying sludge, it is more appropriate to maintain the carbon-nitrogen ratio of the nitrification influent at 2 to 5. In this embodiment, the carbon-nitrogen ratio of the nitrification influent is controlled to be 5.

[0036] In this step, the ammonia nitrogen concentration of the influent is 100mg / L to 200mg / L. The ammonia nitrogen concentration of the biochemical influent of a general biochemical station during daily operation is maintained at 30 to 60mg / L. In order to cultivate nitrifying sludge, a culturing method is usually used to increase the ammonia nitrogen concentration of the influent by a gradient. However, this cultivation method has a long cycle, generally 100 to 300 days. At the same time, due to the lack of continuous drainage, intermittent cultivation generally has accumulation of nitrite nitrogen. The present invention maintains the nitrification influent ammonia nitrogen concentration of the nitrifying sludge cultivation unit at 100mg / L, resulting in less accumulation of nitrite nitrogen, faster increase in nitrification rate, and the cultivated nitrifying sludge can achieve a higher nitrification rate faster and better.

[0037] (3) Continuous water inflow cultivation: After 30 days of intermittent water inflow cultivation, when the nitrification rate reaches 20 mg / (L·h), the nitrification effect of intermittent water inflow cultivation tends to be stable, and continuous water inflow cultivation (also with biochemical water and ammonia-containing wastewater) is started, that is, continuous water inflow and continuous water outflow, without stopping the reaction to drain water intermittently. The ammonia nitrogen concentration of the influent in the regulating tank is controlled to 300 mg / L, the carbon-nitrogen ratio is 3, the hydraulic retention time is 24 hours, the dissolved oxygen in the anoxic tank is controlled to 0.15-0.35 mg / L, the dissolved oxygen in the aerobic tank is controlled to 3 mg / L-5 mg / L, and the pH is 7.0-8.5. Nitrification reaction is carried out in the aerobic tank to obtain nitrified sludge. In the aerobic tank, part of the nitrified liquid (containing nitrate nitrogen) is returned to the anoxic tank through the nitrification liquid return pipe. The amount of refluxed nitrified liquid is 200% of the influent flow rate.

[0038] In this step, the influent ammonia nitrogen concentration is preferably 200 mg / L to 500 mg / L, and in this embodiment, it is controlled at 300 mg / L. Nitrifying sludge cultured with continuous influent generally has a lower accumulation of nitrite nitrogen, and the actual operation of the project is simpler. The influent ammonia nitrogen concentration of continuous influent culture is higher than that of intermittent culture, and the nitrification rate achieved is also higher than that of intermittent culture. At the same time, in order to facilitate the periodic addition of nitrifying sludge in step (4), it is more reasonable to maintain continuous influent culture for long-term operation.

[0039] (4) Low temperature denitrification: When the biochemical denitrification system is operated at a low temperature of 15°C, the nitrified sludge obtained in the aerobic tank in step (3) is periodically added to the biochemical denitrification system, specifically to the biochemical denitrification system A. 2 In the O pool of O or A / O, the nitrification rate of the biochemical system during low temperature operation is greater than 2 mg / (L·h), achieving nitrification enhancement of low temperature denitrification. In this embodiment, the periodic addition of nitrification sludge is 10 days, and the amount added each time is 5% of the volume of the biochemical denitrification system, so that the biochemical denitrification system (A 2 O or A / O) can achieve a nitrification rate of 6.5 mg / (L·h) when running at a low temperature of 15℃ in winter, and still has a good denitrification effect.

[0040] When the biochemical denitrification system is operated at low temperatures in winter, the active ingredients in the system sludge decrease, the activity of nitrifying bacteria decreases, and the denitrification efficiency of the system drops significantly. The proportion of nitrifying bacteria in the nitrifying sludge cultivated in steps (1)-(3) increases significantly. Periodically adding it to the biochemical system, on the one hand, because the composition of the nitrifying influent is similar to that of the biochemical denitrification system influent, it has good environmental compatibility and is not easily lost. On the other hand, it increases the concentration of nitrifying bacteria in the biochemical system, with more active ingredients, more nitrifying bacteria participating in biochemical denitrification, and better denitrification effect.

[0041] Example 2

[0042] A nitrification enhancement method for low-temperature denitrification of the present invention, such as Figure 1As shown, the following steps are included:

[0043] (1) Inoculating sludge: Prepare a nitrifying sludge culture unit, which includes a regulating tank, an anoxic tank and an aerobic tank connected in sequence. Both the anoxic tank and the aerobic tank are equipped with a plug flow reactor. The aerobic tank is also equipped with an online monitoring device, which includes an aeration device, a pH probe, a dissolved oxygen probe and a temperature probe. The aerobic tank is also connected to the anoxic tank through a nitrification liquid return pipe.

[0044] While the aerobic tank is being stirred and aerated, the biochemical system sludge (specifically the sludge from the biochemical station concentration tank) with a total nitrogen removal rate of 60% is added to the aerobic tank as inoculated sludge. During subsequent intermittent water inlet culture and continuous water inlet culture, the sludge concentration in the aerobic tank is controlled to be 6500 mg / L.

[0045] (2) Intermittent water inlet cultivation: send the biochemical inlet water and ammonia-containing wastewater into the regulating tank, the carbon-nitrogen ratio of the biochemical inlet water is 8, the ammonia nitrogen concentration is 65 mg / L, the ammonia nitrogen concentration of the ammonia-containing wastewater is 5000 mg / L, and the ammonia-containing wastewater uses the ammonia-containing wastewater of the power plant. The biochemical inlet water and the ammonia-containing wastewater are mixed evenly, and the ammonia nitrogen concentration of the inlet water is controlled to be 150 mg / L and the carbon-nitrogen ratio is 2. The pH value is adjusted to 8.5 to obtain nitrified inlet water. The nitrified inlet water is sent from the regulating tank to the anoxic tank, and the dissolved oxygen in the anoxic tank is controlled to be The concentration of dissolved oxygen in the anoxic tank is 0.15mg / L to 0.35mg / L. Denitrification reaction is carried out in the anoxic tank. The effluent from the anoxic tank flows into the aerobic tank. The dissolved oxygen in the aerobic tank is controlled to 3mg / L to 5mg / L, and the pH is adjusted to 7.0 to 8.5. Nitrification reaction is carried out in the aerobic tank. After nitrification reaction, the water is discharged. After the discharge, the above water inlet and water outlet operations are repeated for intermittent water inlet cultivation. Each intermittent water inlet cultivation has a water inlet time of 2 hours, a hydraulic retention time of 10 hours, and a drainage time of 1 hour. In the aerobic tank, part of the nitrified liquid is returned to the anoxic tank through the nitrified liquid return pipe. The amount of nitrified liquid returned is 250% of the water inlet flow rate.

[0046] (3) Continuous water inflow cultivation: After 60 days of intermittent water inflow cultivation, when the nitrification rate reaches 13 mg / (L·h), the nitrification effect of intermittent water inflow cultivation tends to be stable, and continuous water inflow cultivation is started, that is, continuous water inflow and continuous water outflow, without stopping the reaction to drain water intermittently. The ammonia nitrogen concentration of the influent in the regulating tank is controlled to 500 mg / L, the carbon-nitrogen ratio is 4, the hydraulic retention time is 48 hours, the dissolved oxygen in the anoxic tank is controlled to 0.15-0.35 mg / L, the dissolved oxygen in the aerobic tank is controlled to 3 mg / L-5 mg / L, and the pH is 7.0-8.5. Nitrification reaction is carried out in the aerobic tank to obtain nitrified sludge. In the aerobic tank, part of the nitrified liquid is returned to the anoxic tank through the nitrified liquid return pipe. The amount of nitrified liquid returned is 250% of the influent flow rate.

[0047] (4) Low temperature denitrification: When the biochemical denitrification system is operated at a low temperature of 15°C, the nitrified sludge obtained in the aerobic tank in step (3) is periodically added to the biochemical denitrification system, specifically to the biochemical denitrification system A. 2 In the O pool of O or A / O, the nitrification rate of the biochemical system during low temperature operation is greater than 2 mg / (L·h), achieving nitrification enhancement of low temperature denitrification. In this embodiment, the periodic addition of nitrification sludge is 30 days, and the amount added each time is 1% of the volume of the biochemical denitrification system, so that the biochemical denitrification system (A 2 O or A / O) can achieve a nitrification rate of 4.4 mg / (L·h) at a low temperature of 15℃ in winter, which still has a good denitrification effect.

[0048] Example 3

[0049] A nitrification enhancement method for low-temperature denitrification of the present invention, such as Figure 1 As shown, the following steps are included:

[0050] (1) Inoculating sludge: Prepare a nitrifying sludge culture unit, which includes a regulating tank, an anoxic tank and an aerobic tank connected in sequence. Both the anoxic tank and the aerobic tank are equipped with a plug flow reactor. The aerobic tank is also equipped with an online monitoring device, which includes an aeration device, a pH probe, a dissolved oxygen probe and a temperature probe. The aerobic tank is also connected to the anoxic tank through a nitrification liquid return pipe.

[0051] While the aerobic tank is being stirred and aerated, the biochemical system sludge (specifically the sludge from the biochemical station concentration tank) with a total nitrogen removal rate of 80% is added to the aerobic tank as inoculated sludge. During subsequent intermittent water inlet culture and continuous water inlet culture, the sludge concentration in the aerobic tank is controlled to be 2500 mg / L.

[0052] (2) Intermittent water inlet cultivation: The biochemical inlet and ammonia-containing wastewater are pumped into the regulating tank in a certain proportion. The carbon-nitrogen ratio of the biochemical inlet is 12, the ammonia nitrogen concentration is 60 mg / L, and the ammonia nitrogen concentration of the ammonia-containing wastewater is 3000 mg / L. The ammonia-containing wastewater uses the ammonia-containing wastewater from the power plant. The biochemical inlet and the ammonia-containing wastewater are mixed evenly, and the ammonia nitrogen concentration of the inlet is controlled to be 200 mg / L and the carbon-nitrogen ratio is 4. The pH value is adjusted to 8.5 to obtain nitrified inlet water. The nitrified inlet water is sent from the regulating tank to the anoxic tank to control the dissolved The dissolved oxygen concentration is 0.15mg / L to 0.35mg / L, and denitrification is carried out in the anoxic tank. The effluent from the anoxic tank flows into the aerobic tank, where the dissolved oxygen is controlled at 3mg / L to 5mg / L, and the pH is adjusted to 7.0 to 8.5. Nitrification is carried out in the aerobic tank, and the water is drained after nitrification. After drainage, the above-mentioned water inlet and water outlet operations are repeated for intermittent water inlet cultivation. Each intermittent water inlet cultivation has a water inlet time of 2 hours, a hydraulic retention time of 24 hours, and a drainage time of 2 hours. In the aerobic tank, part of the nitrified liquid is returned to the anoxic tank through the nitrified liquid return pipe, and the amount of nitrified liquid returned is 300% of the water inlet flow rate.

[0053] (3) Continuous water inflow cultivation: After 15 days of intermittent water inflow cultivation, when the nitrification rate reaches 16 mg / (L·h), the nitrification effect of intermittent water inflow cultivation tends to be stable, and continuous water inflow cultivation is started, that is, continuous water inflow and continuous water outflow, without stopping the reaction to drain water intermittently. The ammonia nitrogen concentration of the influent in the regulating tank is controlled to 200 mg / L, the carbon-nitrogen ratio is 5, the hydraulic retention time is 10 hours, the dissolved oxygen in the anoxic tank is controlled to 0.15-0.35 mg / L, the dissolved oxygen in the aerobic tank is controlled to 3 mg / L-5 mg / L, and the pH is 7.0-8.5. Nitrification reaction is carried out in the aerobic tank to obtain nitrified sludge. In the aerobic tank, part of the nitrified liquid is returned to the anoxic tank through the nitrification liquid return pipe. The amount of nitrified liquid returned is 300% of the influent flow rate.

[0054] (4) Low temperature denitrification: When the biochemical denitrification system is operated at a low temperature of 15°C, the nitrified sludge obtained in the aerobic tank in step (3) is periodically added to the biochemical denitrification system, specifically to the biochemical denitrification system A. 2 In the O pool of O or A / O, the nitrification rate of the biochemical system during low-temperature operation is greater than 2 mg / (L·h), achieving nitrification enhancement of low-temperature denitrification. In this embodiment, the periodic addition of nitrification sludge is 1 day, and the amount added each time is 10% of the volume of the biochemical denitrification system, so that the biochemical denitrification system (A 2 O or A / O) can achieve a nitrification rate of 5.6 mg / (L·h) at a low temperature of 15℃ in winter, and still has a good denitrification effect.

[0055] Comparative Example 1

[0056] A low-temperature denitrification method for an A / O biochemical denitrification system comprises the following steps:

[0057] The biochemical influent first enters the primary sedimentation tank for sedimentation, then enters the A / O biochemical denitrification system for biochemical denitrification, and then enters the secondary sedimentation tank for sedimentation. The biochemical effluent is discharged, and the secondary sedimentation tank sludge is concentrated, filtered, and incinerated. At the low temperature of 15°C in winter, the nitrification rate of the A / O biochemical denitrification system is 1.8mg / (L·h) or less.

[0058] The above description is only a preferred embodiment of the present invention and does not constitute any formal limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A nitrification enhancement method for low-temperature denitrification, characterized in that: The following steps are involved: (1) Inoculation sludge: Prepare a nitrification sludge cultivation unit, which includes a regulating tank, an anoxic tank, and an aerobic tank connected in sequence; add the biochemical system sludge with a total nitrogen removal rate of 60% to 80% as inoculation sludge to the aerobic tank, stirring and aerating while adding; (2) Intermittent water inflow cultivation: biochemical inflow and ammonia-containing wastewater are sent to the regulating tank, the carbon-nitrogen ratio of the biochemical inflow is 8-15, and the ammonia nitrogen concentration of the ammonia-containing wastewater is 300mg / L-10000mg / L. After mixing, the ammonia nitrogen concentration of the inflow is controlled to be 100mg / L-200mg / L, the carbon-nitrogen ratio is 2-5, and the pH value is adjusted to 7.5-8.5 to obtain nitrified inflow. The nitrified inflow is sent from the regulating tank to the anoxic tank, the dissolved oxygen in the anoxic tank is controlled to be 0.15mg / L-0.35mg / L, and denitrification reaction is carried out in the anoxic tank. The effluent from the anoxic tank flows into the aerobic tank, the dissolved oxygen in the aerobic tank is controlled to be 1.5mg / L-8mg / L, and the pH value is adjusted to 7.0-8.5, and nitrification reaction is carried out in the aerobic tank. After nitrification reaction, the water is discharged; after drainage, the above-mentioned water inflow to drainage operation is repeated to carry out intermittent water inflow cultivation; (3) Continuous water inflow cultivation: When the nitrification rate of intermittent water inflow cultivation reaches 13 mg / (L·h) to 20 mg / (L·h), continuous water inflow cultivation is started, and the ammonia nitrogen concentration of the influent in the regulating tank is controlled to be 200 mg / L to 500 mg / L and the carbon-nitrogen ratio is 2 to 5. The dissolved oxygen in the anoxic tank is controlled to be 0.10 mg / L to 0.35 mg / L, and denitrification reaction is carried out in the anoxic tank. The dissolved oxygen in the aerobic tank is controlled to be 1.5 mg / L to 8 mg / L and the pH value is 7.0 to 8.5, and nitrification reaction is carried out in the aerobic tank to obtain nitrified sludge; (4) Low-temperature denitrification: When the biochemical denitrification system is operated at a low temperature, the low temperature is 13°C to 19°C, and the nitrified sludge obtained from the aerobic tank in step (3) is periodically added to the biochemical denitrification system, so that the nitrification rate of the biochemical system when operating at a low temperature is greater than 2 mg / (L·h), thereby achieving nitrification enhancement of low-temperature denitrification; In step (2) and step (3), part of the nitrification liquid produced in the aerobic tank is returned to the anoxic tank through the nitrification liquid return pipe, and the amount of the part of the nitrification liquid is 200% to 300% of the inlet water flow rate.

2. The nitrification enhancement method for low-temperature denitrification according to claim 1, characterized in that: The time required for the intermittent water infusion culture in step (3) to reach the nitrification rate is 15 to 60 days.

3. The nitrification enhancement method for low-temperature denitrification according to claim 1, characterized in that: In step (3), the hydraulic retention time of the continuous water inlet culture is 10 hours to 48 hours.

4. The nitrification enhancement method for low-temperature denitrification according to claim 1, characterized in that: In step (4), the time for periodically adding nitrification sludge is 1 day to 30 days, and the amount of periodically added nitrification sludge each time is 1% to 10% of the volume of the biochemical denitrification system.

5. The nitrification enhancement method for low-temperature denitrification according to any one of claims 1 to 4, characterized in that: During the intermittent water inlet culture and the continuous water inlet culture, the sludge concentration in the aerobic tank is controlled to be 2500 mg / L to 6500 mg / L.

6. The nitrification enhancement method for low-temperature denitrification according to any one of claims 1 to 4, characterized in that: In step (2), each time water is intermittently added to the culture, the water addition time is 1 hour to 2 hours, the hydraulic retention time is 10 hours to 24 hours, and the drainage time is 1 hour to 2 hours.

7. The nitrification enhancement method for low-temperature denitrification according to any one of claims 1 to 4, characterized in that: In step (2), the ammonia-containing wastewater is one or more of the ammonia-containing wastewater from the biochemical station filter press, the ammonia-containing wastewater from the power plant, and the ammonia-containing wastewater from the production workshop.

8. The nitrification enhancement method for low-temperature denitrification according to any one of claims 1 to 4, characterized in that: The anoxic tank is provided with an agitator or a plug flow reactor, the aerobic tank is provided with an agitator or a plug flow reactor, the aerobic tank is further provided with an online monitoring device and an aeration device, the online monitoring device includes a pH probe, a dissolved oxygen probe and a temperature probe, and the aerobic tank is connected to the anoxic tank through a nitrification liquid reflux pipe.

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