CN104129853B - A kind of starting method of quick short distance nitration - Google Patents

Abstract

The invention discloses a kind of starting method of rapidly and efficiently short distance nitration, the method is: import in sbr reactor device by the seed sludge being rich in nitrobacteria; Sewage being imported sbr reactor device makes the concentration of mud in reactor be 2500 ~ 3500mg/L, controls sewage temperature 30 ± 1 DEG C, pH7.9 ~ 8.2; The aeration facility starting reactor makes dissolved oxygen concentration be 0.8 ~ 1.2mg/L; Aeration time is 1.5 ~ 2.5h; Stop aeration, open stirring and muddy water is mixed, stir 0.5 ~ 1.5h; Repeat 1 ~ 5 aeration and stirring operation; Then leave standstill and make solid-liquid separation; Discharge supernatant liquor.The present invention carries out short distance nitration in intermittent aeration mode, compared to traditional continuous aeration, the growth of AOB can be promoted better, suppress nitration reaction, and effectively can reduce the energy consumption of reaction unit, the startup of the short distance nitration of the sanitary sewage to low ammonia-nitrogen content can be realized.

Description

A start-up method of rapid short-cut nitrification

technical field

The invention belongs to the field of sewage treatment and relates to a fast and efficient start-up method for short-range nitrification, in particular to a process and method for realizing short-range nitrification and accumulation of nitrite under low ammonia nitrogen conditions.

Background technique

Currently, conventional biological nitrification/denitrification is still the main method for denitrification of sewage. Although it has cost advantages compared with physical and chemical denitrification methods, it still has disadvantages such as low efficiency, high energy and material consumption, and large amount of residual sludge. With the in-depth understanding of nitrogen conversion pathways, a series of new nitrogen removal processes have been developed to address the inherent shortcomings of traditional nitrogen removal processes. Such as anaerobic ammonia oxidation process, short-cut nitrification and denitrification process, etc. Compared with the traditional denitrification process, the anaerobic ammonium oxidation process and the short-cut nitrification and denitrification process are the cutting-edge technologies for the current sewage denitrification treatment. , significantly reducing the amount of sludge produced, and other advantages provide a new research direction for the current sewage denitrification technology, especially in the current situation of pursuing high efficiency and low energy consumption in sewage treatment, it has attracted more and more attention.

Short-cut nitrification, as the premise of ANANMOX (Anammox Anaerobic AmmoniuOxidation, anaerobic ammonium oxidation) and short-cut nitrification and denitrification process, is to use the difference in nitrogen conversion between ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) to control ammonia nitrogen oxidation at The NO ₂ ^- -N stage eliminates the two steps of oxidizing nitrite to nitrate and reducing to nitrite in traditional biological denitrification. How to achieve efficient nitrite accumulation restricts anammox and reaction. Development of nitrification process.

At present, the main process methods for realizing short-range nitrification are: the SHARON short-range nitrification process proposed by Hellinga et al. for high-temperature and high-ammonia-nitrogen wastewater. At about 35°C, the high-ammonia-nitrogen wastewater is treated in a fully mixed reactor to control the hydraulic retention time ( HRT) is equal to the sludge residence time (SRT) to achieve short-range nitrification. The SHARON short-cut nitrification process is mainly used in the treatment of digested sludge dehydration liquid, landfill leachate and pig wastewater and other high ammonia nitrogen wastewater treatment. Han Xiaoyu et al. (Startup and maintenance of short-cut nitrification with FA and FNA as control factors[J]. Environmental Science, 2009, 03) used continuous flow A/O reactor to treat digested sludge dewatering liquid using FA (free ammonia) and FNA ( Free nitrite) combined inhibition to achieve stable short-range nitrification. This method is mainly aimed at the impact of FA and FNA on short-range nitrification under high ammonia nitrogen conditions, and has certain limitations. Yan Lilong et al. (Effect of pH value on short-range nitrification characteristics of pig farm wastewater at room temperature [J]. Journal of Agricultural Machinery, 2011, 42 (10)) used water inflow for 5 minutes, aeration for 300 minutes, sedimentation for 40 minutes, drainage for 10 minutes, and idle time for 5 minutes. The operation mode of running 4 cycles has realized the nitrification of high ammonia nitrogen pig farm wastewater, the pH value is 7.0-9.5, and the nitrite accumulation rate is between 75% and 80%. This research is mainly aimed at high ammonia nitrogen wastewater, and adopts The traditional short-cut nitrification process adopts a one-way control process, the short-cut nitrification rate is low, and the conversion of nitrite to nitrate is prone to occur.

It can be seen that the current short-range nitrification research on high-ammonia nitrogen wastewater is relatively mature. For the short-range nitrification of urban domestic sewage with low ammonia nitrogen, due to the low concentration of the substrate and slow domestication of ammonia oxidizing bacteria, there are relatively few mature short-range nitrification results. Most of them are in the stage of experimental research, and how to maintain the long-term stable existence of nitrite after accumulation is the key to the short-range biological denitrification technology; while the traditional short-range nitrification process adopts a one-way control process, that is, "water intake→stirring→exposure Air→sedimentation→water effluent” operation mode, in which the control of aeration time is generally adjusted according to the change of pH, which is difficult to operate, and the existing automatic control technology is difficult to meet the needs; on the other hand, AOB is very vulnerable to dissolution Oxygen (DO), because the aeration time is difficult to control, it is easy to cause nitrite to be oxidized to nitrate, which is not conducive to the growth of short-range nitrification ammonium oxidizing bacteria, and there are still some difficulties in stably realizing nitrification; especially short-range nitrification The proliferation and domestication of strain AOB still has the problem of low start-up efficiency.

CN102173536B discloses a high-efficiency short-range nitrification method realized in a nitrification tank by using an inhibitor. In the method, by setting a regulating tank, a nitrification tank and a sedimentation tank, and through the action of autotrophic bacteria, part or all of the ammonia nitrogen in the liquid is oxidized into Nitrite nitrogen; the mud-water mixture flowing out of the nitrification tank is precipitated in the sedimentation tank, and after solid-liquid separation, the effluent enters the denitrification tank, and the sludge enters the nitrification tank through a circulating pump; before the nitrification tank, a regulating tank is set. The ammonia nitrogen online measuring device, the flow rate of the water inlet pump and the circulating pump are installed in the regulating tank. The method has an influent ammonia nitrogen concentration of 500-2000 mg/L, and is not suitable for low ammonia nitrogen wastewater with an influent ammonia nitrogen concentration lower than 50 mg/L. Moreover, parameters such as the hydraulic retention time of this method need to be regulated according to the concentration of ammonia nitrogen in the influent, lacking system operating parameters, and the operation is relatively complicated, which is not conducive to actual production. CN101638267A discloses a rapid start-up method for short-range nitrification of ammonia-containing wastewater. By adopting intermittent operation mode, the initial concentration of ammonia nitrogen is gradually increased from 200-300 mg/L to 400-700 mg/L, pH=7.8-8.5, and the hydraulic pressure of continuous operation mode is The residence time is 14~20h, which realizes the rapid start of short-cut nitrification; however, this method adopts the method of gradually increasing the ammonia nitrogen concentration from 50mg/L to 100mg/L, and the concentration of nitrogen-containing wastewater is basically stable in reality. The method is difficult to operate, and it is not suitable for low-ammonia-nitrogen urban domestic sewage.

Therefore, there is an urgent need to develop a set of treatment methods and technologies that can quickly and stably realize short-range nitrification of low-ammonia wastewater, so as to provide new ideas for reducing consumption and emission of urban sewage treatment processes.

Contents of the invention

In order to solve the above-mentioned existing problems, the present invention adopts a sequenced batch (SBR) bioreactor, adopts an intermittent aeration method, and combines specific temperature, dissolved oxygen, and pH to solve the current short-range nitrification process (especially low-ammonia nitrogen domestic sewage There are problems such as slow proliferation efficiency of ammonia oxidizing bacteria (AOB), low nitrite accumulation efficiency, and long start-up period of short-cut nitrification.

The purpose of the present invention is to provide a fast and efficient start-up method for short-range nitrification.

The technical scheme that the present invention takes is:

A method for starting fast and efficient short-range nitrification, comprising the following steps:

1) Introduce the inoculum sludge rich in nitrifying bacteria into the SBR reactor;

2) Water intake: import the sewage to be treated into the SBR reactor so that the sludge concentration MLSS in the reactor is 2500~3500mg/L, and control the temperature of the sewage to be 30±1°C and pH7.9~8.2;

3) Aeration: Start the aeration facility in the SBR reactor to make the reactor an aerobic environment, in which the dissolved oxygen concentration is 0.8~1.2mg/L; the aeration time is 1.5~2.5h;

4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the SBR reactor are fully mixed and then close the stirring facility; the stirring time is 0.5~1.5h;

5) Repeat step 3) and step 4) 1 to 5 times;

6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid;

7) Water outlet: discharge the supernatant.

Further, in step 1), the inoculum sludge concentration MLSS is 4500-5000 mg/L.

Further, in step 2), the chemical oxygen demand (COD) of the sewage is 150-200 mg/L.

Further, in step 2), the ammonia nitrogen concentration of the sewage is above 40 mg/L.

Further, in step 2), the ammonia nitrogen concentration of the sewage is 40-60 mg/L.

Further, in step 6), the natural precipitation time is 0.5h~1h.

Further, after step 7) is completed, new sewage to be treated is replenished into the reactor to enter the next round of cycle operation.

The beneficial effects of the present invention are:

1) The present invention establishes a relatively complete short-cut nitrification realization method, including how to carry out the proliferation and cultivation of ammonia oxidizing bacteria, and the control conditions for realizing the maximum accumulation of nitrite, and effectively solves the short-cut nitrification process of the SBR process through the membrane-hanging method. The problems of slow bacterial growth and low conversion efficiency of ammonia nitrogen in the process laid the foundation for the actual operation of the project.

2) The present invention creatively proposes an intermittent aeration method for short-range nitrification. Compared with traditional continuous aeration, it has a significant effect on promoting the growth of AOB and inhibiting the nitrification reaction, and can effectively reduce the energy consumption of the reaction device.

3) The present invention provides the use of SBR (sequenced batch activated sludge process) process to achieve short-range nitrification of urban domestic sewage with low ammonia nitrogen. Various control factors include specific parameters such as temperature, dissolved oxygen, pH, and intermittent aeration operation time. It is innovative to combine ANAMMOX and denitrification technology to remove ammonia nitrogen.

4) The present invention adopts the whole automatic control module to operate, the control is simple and feasible, and has important reference value for engineering application.

Description of drawings

Figure 1 shows the concentration changes of NH ₄ ⁺ -N, NO ₂ ^- -N, NO ₃ ^- -N during the start of short-cut nitrification;

Figure 2 shows the change of ammonia nitrogen removal rate and nitrite nitrogen accumulation rate during the start of short-range nitrification;

Fig. 3 shows the concentration changes of NH ₄ ⁺ -N, NO ₂ ^- -N, NO ₃ ^- -N and the removal rate of NH ₄ ⁺ -N and accumulation rate of NO ₂ ^- -N in different periods of short-cut nitrification.

detailed description

A method for starting fast and efficient short-range nitrification, comprising the following steps:

1) Introduce the inoculum sludge rich in nitrifying bacteria into the SBR reactor;

2) Water intake: import the sewage to be treated into the SBR reactor so that the sludge concentration MLSS in the reactor is 2500~3500mg/L, and control the temperature of the sewage to be 30±1°C and pH7.9~8.2;

3) Aeration: Start the aeration facility in the SBR reactor to make the reactor an aerobic environment, in which the dissolved oxygen concentration is 0.8~1.2mg/L; the aeration time is 1.5~2.5h;

4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the SBR reactor are fully mixed and then close the stirring facility; the stirring time is 0.5~1.5h;

5) Repeat step 3) and step 4) 1 to 5 times;

6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid;

7) Water outlet: discharge the supernatant.

Preferably, in step 1), the inoculum sludge concentration MLSS is 4500-5000 mg/L.

Preferably, in step 2), the chemical oxygen demand (COD) of the sewage is 150-200 mg/L.

Preferably, in step 2), the ammonia nitrogen concentration of the sewage is above 40mg/L.

More preferably, in step 2), the ammonia nitrogen concentration of the sewage is 40-60 mg/L.

Preferably, in step 5), repeat step 3) and step 4) twice;

Preferably, in step 6), the natural precipitation time is 0.5h~1h.

Preferably, after step 7) is completed, new sewage to be treated is replenished into the reactor to enter the next round of cycle operation.

The present invention will be further described below in conjunction with specific embodiments, and the protection scope of the present invention is not limited thereto.

Example 1:

1. The start of fast and efficient short-range nitrification includes the following steps:

1) Introduce the inoculation sludge rich in nitrifying bacteria into the SBR reactor, the inoculation sludge is the return sludge of the secondary sedimentation tank of the municipal sewage plant; the concentration of the inoculation sludge MLSS is 4800mg/L; the reactor adopts intermittent operation mode;

2) Influent water: import the sewage to be treated into the SBR reactor, so that the inoculation sludge concentration MLSS in the previous step is 3000mg/L, control the temperature of the sewage to be 30±1°C, pH8, and the chemical oxygen demand COD of the sewage to be treated 170mg/L, ammonia nitrogen concentration 50mg/L;

3) Aeration: Start the aeration facility in the reactor to make the reactor an aerobic environment, in which the dissolved oxygen DO concentration is 1mg/L; the aeration time is 2h;

4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the reactor are fully mixed and then close the stirring facility; the stirring time is 1h;

5) Repeat step 3) and step 4) twice;

6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid. The natural precipitation time is 0.5h;

7) Water outlet: Then discharge the supernatant, add new sewage to be treated into the reactor, and enter the next round of cycle operation.

In the start-up phase of this example, the operating cycle time of the SBR reactor is about 10.3 hours (water inflow is 0.3 hours, aeration/stirring is performed alternately 3 times for 3 hours each, precipitation is 0.5 hours, water outlet is 0.5 hours, a total of 10.3 hours).

The SBR reactor runs two cycles a day, each cycle 10.3h. And the test found that 2, 3, 4, 5, and 6 times of alternating aeration/stirring can start short-range nitrification quickly and efficiently, but when the aeration/stirring alternately runs 3 times, the nitrite accumulation rate is the highest, and the overall test effect optimal.

2. Strain adjustment period

When the above SBR reactor was operated from the 0th day to the 6th day, because the activated sludge was domesticated by inoculation, at this time, both AOB and NOB were in the activity adjustment and adaptation stage and the elimination stage. During this adjustment period, the NO in the effluent ₂ ^- -N concentration ≤ 1.35mg/L, NO ₃ ^- -N concentration ≤ 21.45mg/L, NH ₄ ⁺ -N removal rate ≤ 59.50% (as shown in Figure 1-3); Most of the DO and NH ₄ ⁺ -N are converted into NO ₃ ^- -N by NOB. At this time, NOB still dominates in the mixed liquor, and the whole process of nitrification is mainly carried out in the SBR reactor.

3. Rapid growth period of bacteria

From the 6th day to the 17th day of operation, it is the logarithmic growth period of AOB. From the 6th day of start-up, the concentration of NO ₂ ^- -N in the effluent continuously increases, and the concentration of NO ₃ ^- -N gradually decreases; NH ₄ ⁺ -N is removed The rate initially decreased sharply and then showed an upward trend over time. It shows that with the increase of running time, through the control of the operating conditions of the biochemical reactor, a favorable habitat is created for the growth of AOB, so that the proliferation rate of AOB is higher than that of NOB, and AOB gradually becomes the dominant strain. When running to the 15th day, the concentrations of NO ₃ ^- -N and NO ₂ ^- -N in the effluent water were the same, and the accumulation rate of NO ₂ ^- -N showed a linear upward trend at this stage [NO ₂ ^- -N/(NO ₂ ^- -N+NO ₃ ^- -N)%] up to 89.10% (as shown in Figures 1 to 3).

4. Stable period

From the 17th day to the 30th day of operation, it is the stable growth period of the AOB strain. From the 17th day, the concentrations of NH ₄ ⁺ -N, NO ₂ ^- -N, and NO ₃ ^- -N in the reactor tend to be stable . In the effluent, the concentration of NH ₄ ⁺ -N drops to about 2mg/L, the removal rate reaches 95%, and the accumulation rate of NO ₂ ^- -N [NO ₂ ^- -N/(NO ₂ ^- -N+NO ₃ ^- -N)% ] reached more than 90% (as shown in Figure 1 to Figure 3), and was in a stable state; so far, it shows that the rapid and efficient short-range nitrification of low-ammonia nitrogen wastewater has been successfully realized.

Example 2:

The start of fast and efficient short-cut nitrification includes the following steps:

1) Introduce the inoculation sludge rich in nitrifying bacteria into the SBR reactor, the inoculation sludge is the return sludge of the secondary sedimentation tank of the municipal sewage plant; the concentration of the inoculation sludge MLSS is 4800mg/L; the reactor adopts intermittent operation mode;

2) Influent water: import the sewage to be treated into the SBR reactor, make the concentration of inoculated sludge MLSS in the previous step 3000mg/L, control the temperature of the sewage at 30°C, pH8.0, and the chemical oxygen demand COD of the sewage to be treated 150mg/L, ammonia nitrogen concentration 40mg/L;

3) Aeration: Start the aeration facility in the reactor to make the reactor an aerobic environment, in which the dissolved oxygen DO concentration is 1mg/L; the aeration time is 2h;

4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the reactor are fully mixed and then close the stirring facility; the stirring time is 1h;

5) Repeat step 3) and step 4) twice;

6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid. The natural precipitation time is 1 hour;

7) Water outlet: Then discharge the supernatant, add new sewage to be treated into the reactor, and enter the next round of cycle operation.

Example 3:

The start of fast and efficient short-cut nitrification includes the following steps:

1) Introduce the inoculation sludge rich in nitrifying bacteria into the SBR reactor, the inoculation sludge is the return sludge of the secondary sedimentation tank of the urban sewage plant; the concentration of the inoculation sludge MLSS is 5000mg/L; the reactor adopts intermittent operation mode;

2) Influent water: Import the sewage to be treated into the SBR reactor, so that the inoculation sludge concentration MLSS in the previous step is 3500mg/L, control the temperature of the sewage at 29°C, pH7.9, and the chemical oxygen demand COD of the sewage to be treated 200mg/L, ammonia nitrogen concentration is 60mg/L;

3) Aeration: Start the aeration facility in the reactor to make the reactor an aerobic environment, in which the dissolved oxygen DO concentration is 1.2mg/L; the aeration time is 2.5h;

4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the reactor are fully mixed and then close the stirring facility; the stirring time is 1.5h;

5) Repeat step 3) and step 4) twice;

6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid. The natural precipitation time is 0.5h;

7) Water outlet: Then discharge the supernatant, add new sewage to be treated into the reactor, and enter the next round of cycle operation.

Example 4:

The start of fast and efficient short-cut nitrification includes the following steps:

1) Introduce the inoculation sludge rich in nitrifying bacteria into the SBR reactor, the inoculation sludge is the return sludge of the secondary sedimentation tank of the urban sewage plant; the concentration of the inoculation sludge MLSS is 5000mg/L; the reactor adopts intermittent operation mode;

2) Water intake: import the sewage to be treated into the SBR reactor, so that the concentration of inoculated sludge in the previous step MLSS is 2500mg/L, control the temperature of the sewage to 31°C, pH8.2, and the chemical oxygen demand COD of the sewage to be treated 200mg/L, ammonia nitrogen concentration is 100mg/L;

3) Aeration: Start the aeration facility in the reactor to make the reactor an aerobic environment, in which the dissolved oxygen DO concentration is 0.8mg/L; the aeration time is 1.5h;

4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the reactor are fully mixed and then close the stirring facility; the stirring time is 0.5h;

5) Repeat step 3) and step 4) 4 times;

6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid. The natural precipitation time is 1.5 hours;

7) Water outlet: Then discharge the supernatant, add new sewage to be treated into the reactor, and enter the next round of cycle operation.

The above-mentioned embodiments are only specific embodiments of the present invention, and are not used to limit the implementation scope of the present invention; that is, all equivalent changes and modifications made according to the content of the present invention are covered by the scope of protection claimed by the claims of the present invention.

Claims (4)

1. A start-up method of fast short-range nitrification, characterized in that: comprise the following steps: 1) Introduce the inoculum sludge rich in nitrifying bacteria into the SBR reactor; 2) Water intake: import the sewage to be treated into the SBR reactor so that the sludge concentration MLSS in the reactor is 2500~3500mg/L, and control the temperature of the sewage to be 30±1°C and pH7.9~8.2; 3) Aeration: Start the aeration facility in the SBR reactor to make the reactor an aerobic environment, in which the dissolved oxygen concentration is 0.8~1.2mg/L; the aeration time is 1.5~2.5h; 4) Turn off the aeration facility and turn on the stirring facility at the same time, so that the mud and water in the SBR reactor are fully mixed and then close the stirring facility; the stirring time is 0.5~1.5h; 5) Repeat step 3) and step 4) 1 to 5 times; 6) After stopping the aeration and stirring, let the reactor stand still to allow the material in it to settle naturally and separate the solid from the liquid; 7) Water outlet: discharge the supernatant; The chemical oxygen demand COD of sewage described in step 2) is 150 ~ 200mg/L; In step 2), the ammonia nitrogen concentration of the sewage is 40-60 mg/L. 2. The start-up method of rapid short-cut nitrification according to claim 1, characterized in that: in step 1), the inoculum sludge concentration MLSS is 4500-5000 mg/L. 3. The start-up method of rapid short-range nitrification according to claim 1, characterized in that in step 6), the natural precipitation time is 0.5h~1h. 4. The start-up method of rapid short-range nitrification according to claim 1, characterized in that: after step 7) is completed, new sewage to be treated is added to the reactor to enter the next round of periodic operation.