Nitrification strengthening method for low-temperature denitrification

Abstract

The invention discloses a nitrification strengthening method for low-temperature denitrification, which comprises the following steps: preparing a nitrification sludge culture unit, adding biochemical system sludge as inoculated sludge into an aerobic tank, feeding biochemical inlet water and ammonia-containing wastewater into a regulating tank, uniformly mixing, feeding into an anoxic tank and the aerobic tank, and carrying out intermittent inlet water culture, when the nitrification rate reaches 13-20 mg / (L.h), continuous water inlet culture is started, and nitrified sludge obtained through culture is periodically added into a biochemical denitrification system for low-temperature denitrification. The method is low in cost, nitrified sludge can be efficiently cultured, and normal operation of a biochemical denitrification system under the low-temperature condition in winter is guaranteed through nitrification strengthening.

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 will significantly inhibit the growth rate of autotrophic nitrifying bacteria and the activity of their own enzymes, reducing the removal efficiency of ammonia nitrogen. The normal growth temperature of most nitrifying bacteria is 20℃~35℃. Low temperatures have a greater impact on the activity of enzymes in microbial cells. When the water temperature is lower than 19℃ in winter, it is necessary to extend the acclimatization time of nitrifying bacteria and increase the hydraulic retention time of the biochemical system to ensure the normal operation of the nitrification system. When the water temperature is lower than 16℃, the nitrification activity drops significantly, the nitrification efficiency drops 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 a variety of measures such as heating and insulation, 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 insulating sewage, on the one hand, increases energy consumption and greatly increases the cost of sewage treatment; on the other hand, due to the high steam consumption and supply shortage in winter, it may not be possible to heat the water to a suitable temperature; (2) The commercially available nitrifying bacteria are relatively single, expensive, environmentally incompatible, 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 relatively 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 on 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 prior art and provide a nitrification enhancement method for low-temperature denitrification, which has low cost, can efficiently cultivate nitrifying sludge, and ensure 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: preparing a nitrifying sludge cultivation unit, the device comprising a regulating tank, an anoxic tank and an aerobic tank connected in sequence; adding biochemical system sludge with a total nitrogen removal rate of 60% to 80% as inoculating sludge into the aerobic tank, stirring and aerating while adding;

[0008] (2) Intermittent water inflow culture: 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 300 mg / L-10000 mg / L. After mixing, the ammonia nitrogen concentration of the inflow is controlled to be 100 mg / L-200 mg / 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 0.15 mg / L-0.35 mg / 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 1.5 mg / L-8 mg / L, and the pH value is adjusted to 7.0-8.5, and nitrification reaction is carried out in the aerobic tank. After the nitrification reaction, the water is discharged; after the discharge, the above-mentioned operation of water inflow to discharge is repeated to carry out intermittent water inflow culture;

[0009] (3) Continuous water inflow culture: When the nitrification rate of intermittent water inflow culture reaches 13 mg / (L·h) to 20 mg / (L·h), continuous water inflow culture is started, the ammonia nitrogen concentration of the influent in the regulating tank is controlled to be 200 mg / L to 500 mg / L, the carbon-nitrogen ratio is controlled to be 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 controlled to be 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 inflow 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 inflow culture is 10 h to 48 h.

[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 day to 30 days, and the amount of nitrifying sludge added 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 2500mg / L to 6500mg / 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 to the culture, the water addition time is 1h to 2h, the hydraulic retention time is 10h to 24h, and the drainage time is 1h to 2h.

[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 step (2) and step (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] The present invention adopts the method of intermittent water inlet cultivation and then continuous water inlet cultivation, which greatly shortens the cultivation time of nitrification sludge, has a simple device and simple operation, and is convenient for engineering application. Compared with the method of gradually increasing the ammonia nitrogen inlet gradient cultivation, the present invention adopts direct cultivation at appropriate ammonia nitrogen concentrations, which will not inhibit the nitrification sludge and accelerate the cultivation 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 water for cultivating nitrifying sludge in the present invention is the influent water 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 the artificially prepared nutrient solution, which is closer to the actual project 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 is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments 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 that are connected in sequence. The anoxic tank and the aerobic tank are both equipped with plug flow reactors. 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 reflux 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 culture: 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 of the biochemical station by filter press. 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, and 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, and the dissolved oxygen in the aerobic tank is controlled to be 3mg / L~5mg / L, and the pH value is adjusted to 7.0~8.5, and nitrification reaction is carried out in the aerobic tank. After the nitrification reaction, the water is discharged; after the discharge, the above-mentioned operation of water intake to discharge is repeated, and intermittent water intake cultivation is carried out. During each intermittent water intake cultivation, the water intake time is 1h, the hydraulic retention time is 24h, and the discharge time is 2h. In the aerobic tank, part of the nitrified liquid (containing nitrate nitrogen) flows back to the anoxic tank through the nitrified liquid return pipe, and the amount of the refluxed nitrified liquid is 200% of the water intake flow.

[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 water of the regulating tank. The cultivation of nitrifying sludge generally requires less carbon source, but in order to ensure a better sedimentation 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 water at 2-5. In this embodiment, the carbon-nitrogen ratio of the nitrification influent water is controlled to be 5.

[0036] In this step, the influent ammonia nitrogen concentration is 100 mg / L to 200 mg / L. The daily operation of the biochemical station usually maintains a biochemical influent ammonia nitrogen concentration of 30 to 60 mg / L. In order to cultivate nitrifying sludge, a taming method of increasing the influent ammonia nitrogen concentration by gradient is usually used. 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 100 mg / L, the accumulation of nitrite nitrogen is less, the nitrification rate increases faster, and the cultured nitrifying sludge can reach a higher nitrification rate faster and better.

[0037] (3) Continuous water inflow culture: After 30 days of intermittent water inflow culture, when the nitrification rate reaches 20 mg / (L·h), the nitrification effect of intermittent water inflow culture tends to be stable, and continuous water inflow culture (same biochemical water inflow and ammonia-containing wastewater) begins, that is, continuous water inflow and continuous water discharge, without stopping the reaction to discharge water intermittently, the ammonia nitrogen concentration of the influent in the regulating tank is controlled to be 300 mg / L, the carbon-nitrogen ratio is 3, the hydraulic retention time is 24h, the dissolved oxygen in the anoxic tank is controlled to be 0.15-0.35 mg / L, the dissolved oxygen in the aerobic tank is controlled to be 3 mg / L-5 mg / L, the pH is 7.0-8.5, and the 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 nitrified liquid return pipe, and 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. The nitrite nitrogen accumulation of the nitrifying sludge in continuous influent cultivation is generally low, and the actual operation of the project is simpler. The influent ammonia nitrogen concentration of continuous influent cultivation is higher than that of intermittent cultivation, and the nitrification rate achieved is also higher than that of intermittent cultivation. 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 cultivation 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, it can be added to the biochemical denitrification system A 2 In the O pool of A / O, the nitrification rate of the biochemical system during low temperature operation is greater than 2 mg / (L·h), achieving low temperature denitrification nitrification enhancement. 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) 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 effective components of the system sludge are reduced, the activity of nitrifying bacteria is reduced, and the system denitrification efficiency is greatly reduced. The proportion of nitrifying bacteria in the nitrifying sludge cultivated through steps (1)-(3) is greatly increased, and it is periodically added to the biochemical system. On the one hand, since the nitrification influent composition is similar to the influent of the biochemical denitrification system, it has good environmental compatibility and is not easy to lose. On the other hand, it increases the concentration of nitrifying bacteria in the biochemical system, with more active components, 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 that are connected in sequence. The anoxic tank and the aerobic tank are both equipped with plug flow reactors. 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 reflux 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 culture: 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, and the ammonia nitrogen concentration of the ammonia-containing wastewater is 5000 mg / L. The ammonia-containing wastewater uses the ammonia-containing wastewater from 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 0.15mg / L~0.35mg / L, denitrification reaction is carried out in the anoxic pool, the effluent of the anoxic pool flows into the aerobic pool, the dissolved oxygen in the aerobic pool is controlled to 3mg / L~5mg / L, the pH value is adjusted to 7.0~8.5, nitrification reaction is carried out in the aerobic pool, and the water is discharged after the nitrification reaction; after the water is discharged, the above-mentioned operation of water inlet to water outlet is repeated, and intermittent water inlet cultivation is carried out. During each intermittent water inlet cultivation, the water inlet time is 2h, the hydraulic retention time is 10h, and the drainage time is 1h. In the aerobic pool, part of the nitrified liquid flows back to the anoxic pool through the nitrified liquid return pipe, and the amount of the refluxed nitrified liquid is 250% of the water inlet flow rate.

[0046] (3) Continuous water inflow culture: After 60 days of intermittent water inflow culture, when the nitrification rate reaches 13 mg / (L·h), the nitrification effect of intermittent water inflow culture tends to be stable, and continuous water inflow culture is started, that is, continuous water inflow and continuous water discharge, without stopping the reaction to discharge water intermittently. The ammonia nitrogen concentration of the influent in the regulating tank is controlled to be 500 mg / L, the carbon-nitrogen ratio is 4, the hydraulic retention time is 48h, the dissolved oxygen in the anoxic tank is controlled to be 0.15-0.35 mg / L, the dissolved oxygen in the aerobic tank is controlled to be 3 mg / L-5 mg / L, the pH is 7.0-8.5, and the 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, and 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, it can be added to the biochemical denitrification system A 2 In the O pool of A / O, the nitrification rate of the biochemical system during low temperature operation is greater than 2 mg / (L·h), achieving low temperature denitrification nitrification enhancement. 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, and 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 that are connected in sequence. The anoxic tank and the aerobic tank are both equipped with plug flow reactors. 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 reflux 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 culture: The biochemical influent and ammonia-containing wastewater are pumped into the regulating tank in a certain proportion. The carbon-nitrogen ratio of the biochemical influent 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 influent and the ammonia-containing wastewater are mixed evenly, and the ammonia nitrogen concentration of the influent 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 influent. The nitrified influent is sent from the regulating tank to the anoxic tank to control the dissolved The dissolved oxygen is 0.15mg / L~0.35mg / L, denitrification reaction is carried out in the anoxic pool, the effluent of the anoxic pool flows into the aerobic pool, the dissolved oxygen in the aerobic pool is controlled to be 3mg / L~5mg / L, the pH value is adjusted to 7.0~8.5, nitrification reaction is carried out in the aerobic pool, and the water is discharged after the nitrification reaction; after the water is discharged, the above-mentioned operation of water inlet to water discharge is repeated, and intermittent water inlet cultivation is carried out. During each intermittent water inlet cultivation, the water inlet time is 2h, the hydraulic retention time is 24h, and the drainage time is 2h. In the aerobic pool, part of the nitrified liquid flows back to the anoxic pool through the nitrified liquid return pipe, and the amount of the refluxed nitrified liquid 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 discharge, without stopping the reaction to discharge water intermittently. The ammonia nitrogen concentration of the influent in the regulating tank is controlled to be 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 be 0.15-0.35 mg / L, the dissolved oxygen in the aerobic tank is controlled to be 3 mg / L-5 mg / L, the pH is 7.0-8.5, and the 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, and the amount of the refluxed nitrified liquid 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, it can be added to the biochemical denitrification system A 2 In the O pool of A / O, the nitrification rate of the biochemical system during low temperature operation is greater than 2 mg / (L·h), achieving low temperature denitrification nitrification enhancement. 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 sludge in the secondary sedimentation tank is filtered and incinerated after sludge concentration. At the low temperature of 15℃ in winter, the nitrification rate of the A / O biochemical denitrification system is 1.8mg / (L·h) or lower.

[0058] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and 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 according to 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) Inoculating sludge: preparing a nitrifying sludge cultivation unit, the device comprising a regulating tank, an anoxic tank and an aerobic tank connected in sequence; adding biochemical system sludge with a total nitrogen removal rate of 60% to 80% as inoculating sludge into the aerobic tank, stirring and aerating while adding; (2) Intermittent water inflow culture: 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 300 mg / L-10000 mg / L. After mixing, the ammonia nitrogen concentration of the inflow is controlled to be 100 mg / L-200 mg / 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 0.15 mg / L-0.35 mg / 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 1.5 mg / L-8 mg / L, and the pH value is adjusted to 7.0-8.5, and nitrification reaction is carried out in the aerobic tank. After the nitrification reaction, the water is discharged; after the discharge, the above-mentioned operation of water inflow to discharge is repeated to carry out intermittent water inflow culture; (3) Continuous water inflow culture: When the nitrification rate of intermittent water inflow culture reaches 13 mg / (L·h) to 20 mg / (L·h), continuous water inflow culture is started, the ammonia nitrogen concentration of the influent in the regulating tank is controlled to be 200 mg / L to 500 mg / L, the carbon-nitrogen ratio is controlled to be 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 controlled to be 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.

2. The nitrification enhancement method for low-temperature denitrification according to claim 1, characterized in that: The time 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 inflow culture is 10 h to 48 h.

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 nitrification sludge added 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 a stirrer or a plug flow reactor, the aerobic tank is provided with a stirrer or a plug flow reactor, the aerobic tank is also provided with an online monitoring device, the online monitoring device includes an aeration device, a pH probe, a dissolved oxygen probe and a temperature probe, and the aerobic tank is connected with the anoxic tank through a nitrification liquid reflux pipe.

9. The nitrification enhancement method for low-temperature denitrification according to claim 8, characterized in that: In step (2) and step (3), part of the nitrified liquid produced in the aerobic pool flows back to the anoxic pool through the nitrified liquid reflux pipe, and the amount of the part of the nitrified liquid is 200% to 300% of the inlet water flow rate.

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