A short-cut nitrification and denitrification rapid start-up process

Abstract

The present application belongs to the technical field of sewage treatment, and relates to a short-cut nitrification and denitrification rapid start-up process, comprising the following steps: sludge inoculation, water inlet: sludge rich in nitrifying bacteria is inoculated into an SBR reactor, and then sewage is introduced; FA medium concentration stress: the FA stress concentration of water inlet of the reactor is controlled to be 9-60 mg / L, and aeration is performed for 4-12 h; FA high concentration stress: the FA stress concentration of water inlet of the reactor is controlled to be 40-180 mg / L, and aeration is performed for 20-40 h; FA medium concentration stress: the FA concentration of water inlet of the reactor is controlled to be 10-80 mg / L, and aeration is performed for 8-20 h; operation: the FA concentration of water inlet of the reactor is controlled to be 5-8 mg / L, and aeration operation is performed. Based on the sensitive difference of AOB and NOB to high-concentration FA stress, the FA concentration is gradually increased from medium concentration to high concentration, and then slowly reduced to low concentration. The nitrite nitrogen accumulation rate is greater than 50% within 3 days of stress, so that the in-situ short-cut nitrification and denitrification rapid start-up in the process of low-ammonia-nitrogen wastewater treatment is realized. Even after the FA concentration is reduced, stable operation can still be maintained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment and relates to a short-cut nitrification and denitrification rapid start-up process. BACKGROUND

[0002] In the field of water pollution control, the main reason for the unsatisfactory total nitrogen removal effect is that the traditional denitrification method (full nitrification and denitrification) has problems such as low denitrification efficiency and high operation cost. The research focus in the field of wastewater biological denitrification has shifted to efficient and low-cost technologies. Compared with traditional denitrification technologies, the short-cut nitrification and denitrification process has attracted widespread attention due to its advantages such as reducing carbon source by 40% and saving 25% of aeration energy.

[0003] However, the conventional short-cut nitrification and denitrification start-up method is based on the control of operating parameters (DO, pH) to achieve AOB enrichment, NOB inhibition and gradual elimination. This method has problems such as long start-up time and unstable nitrite accumulation rate, especially in the process of treating low ammonia nitrogen wastewater, it is difficult to continuously maintain the short-cut effect. For example, in the literature "Short-cut nitrification and denitrification rapid start-up and stable operation research", the short-cut nitrification start-up is achieved under low DO conditions through real-time control of DO and pH. It takes about 25 days to achieve a nitrite accumulation rate of 50% and realize start-up. Patent CN200410017477.7 proposes a short-cut nitrification rapid start-up method for ammonia-containing wastewater. The characteristics of this method are as follows: using aerobic activated sludge as inoculum, adopting continuous operation mode, controlling temperature at 25-28℃, pH at 7.2-7.5, and dissolved oxygen concentration at 2.5-3.0 mg / L to enrich sufficient nitrifying bacteria; when the ammonia nitrogen removal rate reaches 98% and the operation is stable, the pH value is adjusted to 8.0-8.2, the temperature is controlled between 32-35℃, and the dissolved oxygen concentration is controlled between 1.0-1.5 mg / L to select nitrite bacteria and eliminate nitrate bacteria. The initial concentration of ammonia-containing wastewater in the start-up process is 5-6 mmol / L, and the final concentration is 30 mmol / L. The short-cut nitrification rapid start-up can be achieved after 39-46 days of operation. In addition, although adding chemicals (such as hydroxylamine) to achieve short-cut start-up is an effective method, there is a risk of secondary pollution. Therefore, it is necessary to develop a high-efficiency, rapid and green economic short-cut nitrification and denitrification rapid start-up technology.

[0004] Free ammonia (FA) is a kind of protonated ammonia substance. Studies have shown that, compared with AOB, NOB is more sensitive to FA inhibition. Therefore, it is a feasible method to achieve in-situ rapid start-up of short-cut nitrification and denitrification under FA stress conditions. Currently, the conventional short-cut nitrification and denitrification start-up method is to use relatively mild conditions to enrich AOB and inhibit and gradually eliminate NOB. This method has problems such as slow short-cut nitrification start-up and unstable nitrite accumulation rate after start-up. SUMMARY

[0005] The present application aims to provide a short-cut nitrification and denitrification rapid start-up process, which uses high-concentration FA to strongly inhibit the activity of AOB and NOB, and after reducing the concentration of FA, AOB can quickly restore ammonia oxidation activity, but due to the generation of nitrite nitrogen, free nitrous acid (FNA) will also inhibit NOB, under the double inhibition of FA and FNA, the continuous control of low DO and high pH, and the discharge of activated sludge, NOB loses activity and is gradually eliminated, thereby realizing the rapid start-up of short-cut nitrification and denitrification, stable operation of the short-cut process, stable accumulation of nitrite nitrogen after start-up, and efficient denitrification.

[0006] A short-cut nitrification and denitrification rapid start-up process, comprising the following steps:

[0007] Step 1, sludge inoculation and water feeding: inoculating sludge rich in nitrifying bacteria into an SBR reactor, and then introducing sewage;

[0008] Step 2, FA medium concentration stress: controlling the FA stress concentration of the reactor to be 9-60 mg / L, and aerating for 4-12 h;

[0009] Step 3, FA high-concentration stress: controlling the FA stress concentration of the reactor to be 40-180 mg / L, and aerating for 20-40 h to complete the start-up process of short-cut nitrification and denitrification;

[0010] Step 4, FA medium concentration stress: controlling the FA concentration of the reactor to be 10-80 mg / L, and aerating for 8-20 h;

[0011] Step 5, operation: controlling the FA concentration of the reactor to be 5-8 mg / L, and aerating for operation.

[0012] In some embodiments, in the FA medium concentration stress stage of step 2, the ammonia nitrogen concentration of the influent is set to be 100-300 mg / L; in the FA high-concentration stress stage of step 3, the ammonia nitrogen concentration of the influent is set to be 300-900 mg / L; in the FA medium concentration stress stage of step 4, the ammonia nitrogen concentration of the influent is set to be 100-400 mg / L; and in the operation stage of step 5, the ammonia nitrogen concentration of the influent is set to be 30-50 mg / L.

[0013] In some embodiments, the specific method of the FA medium concentration stress in step 2 is: first controlling the FA stress concentration of the reactor to be 18-20 mg / L, and aerating for 3-5 h, and then controlling the FA stress concentration of the reactor to be 35-40 mg / L, and aerating for 7-9 h.

[0014] In some embodiments, the step 3 high concentration of FA stress is specifically: first control the reactor influent FA stress concentration of 45-100 mg / L, aeration 18-22 h, and then control the reactor influent FA stress concentration of 40-75 mg / L, aeration 18-22 h.

[0015] In some embodiments, the step 4 medium concentration of FA stress is specifically: first control the reactor influent FA concentration of 25-40 mg / L, aeration 10-15 h, and then control the reactor influent FA concentration of 13-36 mg / L, aeration 8-15 h.

[0016] In some embodiments, the step 2 medium concentration of FA stress stage is: first set the influent ammonia nitrogen concentration to 90-110 mg / L, aeration 3-5 h, and then set the influent ammonia nitrogen concentration to 190-210 mg / L, aeration 7-9 h; the step 3 high concentration of FA stress stage is: first set the influent ammonia nitrogen concentration to 490-510 mg / L, aeration 18-22 h, and then set the influent ammonia nitrogen concentration to 390-410 mg / L, aeration 18-22 h; the step 4 medium concentration of FA stress stage is: first set the influent ammonia nitrogen concentration to 190-210 mg / L, aeration 10-15 h, and then set the influent ammonia nitrogen concentration to 90-210 mg / L, aeration 8-15 h.

[0017] In some embodiments, during the whole process, the DO range is 0.3-1 mg / L, the pH range is 8-9, the ammonia nitrogen residual amount is 15-35 mg / L, and the carbon-nitrogen ratio is 5-8; preferably, the DO range is 0.5-0.7 mg / L, the pH range is 8-9, the ammonia nitrogen residual amount is 20-30 mg / L, and the carbon-nitrogen ratio is 6-7.

[0018] In some embodiments, in the step 1, the sludge inoculation and influent mode is specifically: taking the sludge of the sewage plant aeration tank treatment unit, inoculating into the SBR reactor after sewage culture, introducing sewage into the SBR reactor, and controlling the sludge concentration MLSS in the SBR reactor to be 6000-7000 mg / L.

[0019] In some embodiments, the carbon-nitrogen ratio of the sewage is 6-7, the ammonia nitrogen is 35-45 mg / L, and the COD is 250-300 mg / L.

[0020] In some embodiments, the aeration operation strategy of the running phase in step 5 is as follows: the SBR running cycle is set to 250-300 min, water feeding is 20-40 min, aeration is 110-130 min, anoxic is 50-70 min, aeration is 20-40 min, sedimentation is 20-40 min, and water discharge is 5-15 min; preferably, the aeration operation strategy is as follows: the SBR running cycle is set to 280 min, water feeding is 30 min, aeration is 120 min, anoxic is 60 min, aeration is 30 min, sedimentation is 30 min, and water discharge is 10 min.

[0021] In summary, the present application includes at least one of the following beneficial technical effects:

[0022] (1) Based on the sensitive difference of AOB and NOB to high-concentration FA stress, by gradually increasing the FA concentration from medium to high, and then slowly reducing it to low, the nitrite nitrogen accumulation rate can reach more than 50% within 3 days of stress, realizing the rapid start of in-situ short-cut nitrification and denitrification. Even in the process of low-ammonia-nitrogen wastewater treatment, a high nitrite nitrogen accumulation rate can be maintained, and stable operation can be maintained after the FA concentration is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The water quality change rule chart of Example 1, wherein T1-T2 represents the sludge inoculation and water feeding stage of the first 2 days of the whole process; T3-T4 represents the medium-concentration stress stage of the first 2 days of FA stress of the third 4 days of the whole process; T5 represents the high-concentration stress stage of the third day of FA stress of the fifth day of the whole process; T6-T7 represents the medium-concentration stress stage of the fourth 5 days of FA stress of the sixth 7 days of the whole process; and T8 represents the running stage of the eighth day of the whole process.

[0024] Figure 2 The water quality change rule chart of Example 2, wherein T1-T2 represents the sludge inoculation and water feeding stage of the first 2 days of the whole process; T3 represents the medium-concentration stress stage of the first day of FA stress of the third day of the whole process; T4-T5 represents the high-concentration stress stage of the second 3 days of FA stress of the fourth 5 days of the whole process; T6 represents the medium-concentration stress stage of the fourth day of FA stress of the sixth day of the whole process; and T7-T8 represents the running stage of the seventh 8 days of the whole process.

[0025] Figure 3The water quality change rule chart of Example 3, wherein T1-T2 represents the sludge inoculation and water feeding stage of the first 2 days of the whole process, T3-T4 represents the third 4 days of the whole process, the first 2 days of FA stress, the medium concentration stress stage, T5-T6 represents the fifth 6 days of the whole process, the third 4 days of FA stress, the high concentration stress stage, T7-T8 represents the seventh 8 days of the whole process, the fourth 5 days of FA stress, the medium concentration stress stage;

[0026] Figure 4 The FA change rule comparison chart of Example 3 and Comparative Example 1;

[0027] Figure 5 The short-cut nitrification and denitrification process pollutant removal performance chart of Example 3;

[0028] Figure 6 The full nitrification and denitrification process pollutant removal performance chart of Comparative Example 1;

[0029] Figure 7 The ammonia nitrogen removal rate chart during the start-up process of Comparative Example 2, wherein T1-T5 represents the sludge inoculation and water feeding stage of the first 5 days of the whole process; T6-T7 represents the sixth 7 days of the whole process, the first 2 days of FA stress, the high concentration stress stage; T8-T10 represents the eighth 10 days of the whole process, the running stage;

[0030] Figure 8 The ammonia nitrogen removal rate and nitrite nitrogen accumulation rate chart during the start-up process of Comparative Example 3, wherein T1-T7 represents the sludge culture and water feeding stage of the first 7 days of the whole process, T8-T9 represents the eighth 9 days of the whole process, the first 2 days of FA stress; T10-T12 represents the tenth 12 days of the whole process, the third 5 days of FA stress. DETAILED DESCRIPTION

[0031] The technical solutions of the present application are further illustrated by specific examples below, and the specific examples do not represent a limitation on the protection scope of the present application. Some non-essential modifications and adjustments made by others according to the concept of the present application still belong to the protection scope of the present application.

[0032] The sewage treated by the present application is simulated domestic sewage, the nitrogen source is ammonium sulfate, and the carbon source is glucose. The inorganic salt medium and trace elements are composed as follows:

[0033] Table 1.1 Composition of artificial simulated domestic sewage

[0034]

[0035] Table 1.2 Composition of trace elements

[0036]

[0037] Example 1

[0038] A short-cut nitrification-denitrification rapid start-up process, comprising the following steps:

[0039] Step 1, sludge inoculation, influent:

[0040] Take the sludge of the aeration tank treatment unit of a sewage plant, configure artificial simulated domestic sewage with ammonia nitrogen concentration of about 40 mg / L and COD concentration of about 280 mg / L, inoculate the seed sludge into the SBR reactor, introduce sewage with carbon-nitrogen ratio of 6-7 into the SBR reactor, control the sludge concentration MLSS in the reactor to be 6000-7000 mg / L, use NaHCO3 to adjust the pH range to be 8.1-8.5, use the aeration pump to control the DO range to be 0.5-1.0 mg / L, and use the pH and DO online monitoring instrument to monitor the pH and DO changes in the system in real time;

[0041] Step 2, concentration stress in FA:

[0042] Set the influent ammonia nitrogen concentration to 100 mg / L, the FA stress concentration in the reactor is 18.49 mg / L, aeration for 4 h, control the DO range to be about 0.5, use NaHCO3 to adjust the pH range to be about 8.5, on the one hand, higher pH is suitable for AOB growth and inhibits NOB activity, on the other hand, higher pH corresponds to higher FA concentration, which causes multiple inhibition effects on NOB, in addition, a certain amount of ammonia nitrogen residue (about 20-30 mg / L) is ensured, at this time, the nitrite nitrogen accumulation rate increases from 0.06% to 28.86%, and further denitrification for 4 h is performed;

[0043] Then increase the influent ammonia nitrogen concentration to 200 mg / L, the FA stress concentration in the reactor is 36.99 mg / L, aeration for 8 h, control the DO range to be about 0.5 by using the air flow meter, at this time, the nitrite nitrogen accumulation rate is 28.32%, and further denitrification for 4 h is performed;

[0044] Step 3, high concentration stress stage in FA:

[0045] Increase the influent ammonia nitrogen concentration to 300 mg / L, the FA stress concentration in the reactor is 55.48 mg / L, due to the high ammonia nitrogen concentration, the oxygen consumption increases, therefore the aeration pump can be appropriately increased, control the DO range to be about 0.5, aeration for 20 h, at this time, the nitrite nitrogen accumulation rate increases to 68.74%, indicating that the short-cut process is started (according to “Study on Rapid Start-up and Stable Operation of Short-cut Nitrification-denitrification of Pig Manure and Straw Biogas” by Gao Xingdong et al., nitrite nitrogen accumulation rate of not less than 50% is considered as successful start-up of short-cut nitrification-denitrification), and further denitrification for 6 h is performed;

[0046] Step 4, concentration stress stage in FA:

[0047] Adjust the ammonia nitrogen concentration of the influent to 200 mg / L, the FA concentration of the influent in the reactor is 29.97 mg / L, aeration for 12 h, control the DO range at about 0.5, the nitrite nitrogen accumulation rate is as high as 100%, at this time, according to the amount of residual ammonia nitrogen in the system, add an appropriate amount of carbon source (keep the residual ammonia nitrogen 20-30 mg / L and the carbon-nitrogen ratio 6-7), this stage starts to gradually increase the activity of AOB and denitrifying bacteria by adding glucose, and further denitrification for 4 h;

[0048] Adjust the ammonia nitrogen concentration of the influent to 100 mg / L, at this time, the FA concentration of the influent in the reactor is 13.95 mg / L, aeration for 8 h, control the DO range at about 0.5, the nitrite nitrogen accumulation rate is as high as 71.11%, similarly, according to the amount of residual ammonia nitrogen in the system, add an appropriate amount of carbon source (keep the residual ammonia nitrogen 20-30 mg / L and the carbon-nitrogen ratio 6-7), further denitrification for 4 h;

[0049] Step 5, running phase:

[0050] Further adjust the ammonia nitrogen concentration of the influent to about 40 mg / L, at this time, the FA concentration of the influent in the reactor is 7.77 mg / L, when the MLSS exceeds 7000 mg / L, a part of sludge can be appropriately discharged, the MLSS control range is 3500-4500 mg / L, because the growth rate of AOB is higher than that of NOB, the NOB in the system can be eliminated by continuous sludge discharge, the aeration strategy (SBR running cycle is set to 280 min: influent for 30 min, aeration for 120 min, anoxic for 60 min, aeration for 30 min, sedimentation for 30 min, and effluent for 10 min), control the DO range at about 0.5, the nitrite nitrogen accumulation rate is 59.10%, still short process.

[0051] Example 2

[0052] A short nitrification and denitrification rapid start-up process, comprising the following steps:

[0053] Step 1, sludge inoculation, influent:

[0054] Take the sludge of the treatment unit of the aeration tank of the sewage plant, configure artificial simulated domestic sewage with ammonia nitrogen concentration of about 40 mg / L and COD concentration of about 280 mg / L, inoculate the seed sludge into the SBR reactor, introduce the sewage with carbon-nitrogen ratio of 6-7 into the SBR reactor, control the sludge concentration MLSS in the reactor to be 6000-7000 mg / L, use NaHCO3 to adjust the pH range to be 8.1-8.5, use the aeration pump to control the DO range to be 0.5-1.0 mg / L, and use the pH and DO online monitoring instrument to monitor the pH and DO changes in the system in real time;

[0055] Step 2, concentration stress stage in FA:

[0056] The ammonia nitrogen concentration of the influent water was set to 100 mg / L, the FA stress concentration of the reactor influent water was 9.71 mg / L, aeration was performed for 4 h, the DO range was controlled to be about 0.5, NaHCO3 was used to adjust the pH range to be about 8.5, at this time, the nitrite nitrogen accumulation rate was 1.55%, and further denitrification was performed for 4 h;

[0057] Step 3, high concentration stress stage in FA:

[0058] The ammonia nitrogen concentration of the influent water was increased to 500 mg / L, the FA stress concentration of the reactor influent water was 47.15 mg / L, because the ammonia nitrogen concentration was very high, the oxygen consumption was increased, therefore, the aeration pump could be appropriately increased, the DO range was controlled to be about 0.5, aeration was performed for 20 h, the nitrite nitrogen accumulation rate was increased to 44.42%, and further denitrification was performed for 6 h;

[0059] Further high concentration FA was used to continuously inhibit NOB, the ammonia nitrogen of the influent water was 400 mg / L, the FA concentration of the reactor influent water was 41.24 mg / L, the DO range was controlled to be about 0.5, aeration was performed for 20 h, the nitrite nitrogen accumulation rate was increased to 59.65%, indicating that the short process was started, and further denitrification was performed for 6 h;

[0060] Step 4, concentration stress stage in FA:

[0061] The ammonia nitrogen concentration of the influent water was adjusted to 100 mg / L, at this time, the FA concentration of the reactor influent water was 10.33 mg / L, aeration was performed for 8 h, the DO range was controlled to be about 0.5, the nitrite nitrogen accumulation rate was 72.56.%, and the same, according to the residual ammonia nitrogen concentration in the system, an appropriate amount of carbon source was added (the residual ammonia nitrogen in the system was maintained to be 20-30 mg / L and the carbon-nitrogen ratio was 6-7), and further denitrification was performed for 4 h;

[0062] Step 5, running stage:

[0063] The ammonia nitrogen concentration of the influent water was further adjusted to be about 40 mg / L, at this time, the FA concentration of the reactor influent water was 5.34 mg / L, when the MLSS exceeded 7000 mg / L, part of the sludge could be appropriately discharged, the MLSS control range was 3500-4500 mg / L, because the growth rate of AOB was higher than that of NOB, the NOB in the system could be eliminated by continuously discharging sludge, the aeration strategy (SBR running cycle was set to 280 min: influent water 30 min, aeration 120 min, anoxic 60 min, aeration 30 min, sedimentation 30 min, and effluent 10 min) was used, the DO range was strictly controlled to be about 0.5, and the nitrite nitrogen accumulation rate was as high as 80.29%.

[0064] Example 3

[0065] A short-cut nitrification-denitrification rapid start-up process, comprising the following steps:

[0066] Step 1, sludge inoculation, influent:

[0067] Take the sludge of the aeration tank treatment unit of a sewage plant, configure artificial simulated domestic sewage with ammonia nitrogen concentration of about 40 mg / L and COD concentration of about 280 mg / L, inoculate the seed sludge into the SBR reactor, introduce the sewage with carbon-nitrogen ratio of 6-7 into the SBR reactor, control the sludge concentration MLSS in the reactor to be 6000-7000 mg / L, adjust the pH range to be 8.1-8.5 by using NaHCO3, control the DO range to be 0.5-1.0 mg / L by using an aeration pump, and monitor the pH and DO changes in the system in real time by using an on-line pH and DO monitor;

[0068] Step 2, concentration stress phase in FA:

[0069] Set the ammonia nitrogen concentration of the influent to be 100 mg / L, the FA stress concentration of the reactor influent to be 19.18 mg / L, control the DO range to be about 0.5 by aeration for 4 h, adjust the pH range to be about 8.5 by using NaHCO3, on the one hand, higher pH is suitable for the growth of AOB and inhibits the activity of NOB, on the other hand, higher pH corresponds to higher FA concentration, which causes multiple inhibition effects on NOB, in addition, a certain amount of residual ammonia nitrogen (about 20-30 mg / L) is needed, at this time, the nitrite nitrogen accumulation rate is 0.66%, and further denitrification is carried out for 4 h;

[0070] Then increase the ammonia nitrogen concentration of the influent to 200 mg / L, the FA stress concentration of the reactor influent to be 40.46 mg / L, control the DO range to be about 0.5 by aeration for 8 h, at this time, the nitrite nitrogen accumulation rate is 23.14%, indicating that the activity of NOB is slightly inhibited under the stress of the FA concentration, and further denitrification is carried out for 4 h;

[0071] Step 3, high concentration stress phase of FA:

[0072] Increase the ammonia nitrogen concentration of the influent to 500 mg / L, the FA stress concentration of the reactor influent to be 98.78 mg / L, since the ammonia nitrogen concentration is very high, the oxygen consumption increases, therefore, the aeration pump can be appropriately increased, the DO range is controlled to be about 0.5, aeration is carried out for 20 h, at this time, the nitrite nitrogen accumulation rate increases to 98.20%, indicating that the short-cut process is started, and further denitrification is carried out for 6 h;

[0073] Reduce the FA concentration of the influent to continuously inhibit NOB, set the ammonia nitrogen concentration of the influent to be 400 mg / L, the FA concentration of the reactor influent to be 73.98 mg / L, control the DO range to be about 0.5, aeration is carried out for 20 h, the nitrite nitrogen accumulation rate increases to 91.37%, and further denitrification is carried out for 6 h;

[0074] Step 4, concentration stress stage in FA:

[0075] The ammonia nitrogen concentration of the influent was adjusted to 200 mg / L, the FA concentration of the influent in the reactor was 38.81 mg / L, aeration was performed for 12 h, the DO range was controlled at about 0.5, and the nitrite nitrogen accumulation rate was as high as 100%. At this time, carbon source was appropriately supplemented according to the amount of residual ammonia nitrogen in the system (the residual ammonia nitrogen was maintained at 20-30 mg / L and the carbon-nitrogen ratio was 6-7), AOB and denitrifying bacteria activity was gradually increased by adding glucose, and further denitrification was performed for 4 h;

[0076] The ammonia nitrogen concentration of the influent was continuously stressed at 200 mg / L, the FA concentration of the influent in the reactor was 36.32 mg / L, aeration was performed for 12 h, the DO range was controlled at about 0.5, and the nitrite nitrogen accumulation rate was as high as 100%. At this time, carbon source was appropriately supplemented according to the amount of residual ammonia nitrogen in the system (the residual ammonia nitrogen was maintained at 20-30 mg / L and the carbon-nitrogen ratio was 6-7), AOB and denitrifying bacteria activity was gradually increased by adding glucose, and further denitrification was performed for 4 h;

[0077] Step 5, running stage:

[0078] The ammonia nitrogen concentration of the influent was further adjusted to about 40 mg / L, at this time the FA concentration of the influent in the reactor was 5.24 mg / L, when the MLSS exceeded 7000 mg / L, part of the sludge could be appropriately discharged, the MLSS control range was 3500-4500 mg / L, because the growth rate of AOB was higher than that of NOB, NOB in the system could be eliminated by continuous sludge discharge, the aeration strategy (SBR operation cycle was set to 280 min: influent for 30 min, aeration for 120 min, anoxic for 60 min, aeration for 30 min, sedimentation for 30 min, and effluent for 10 min) was used, and the DO range was strictly controlled at about 0.5.

[0079] Effect example

[0080] The water quality of Examples 1-3 was monitored, and the specific detection method was as follows:

[0081] NH4 + -N, NO2 - -N, NO3 - -N, TN, MLSS, and COD were determined by the national standard method "National Environmental Protection Bureau. Water and wastewater monitoring and analysis method". 3rd edition. Beijing: China Environmental Publishing House, 1997: 252-272, pH and DO were detected by PHSJ-3F type Leici pH meter and DZB-712 type Leici portable dissolved oxygen meter, respectively.

[0082] The nitrite nitrogen accumulation rate calculation formula is as follows:

[0083] Nitrite nitrogen accumulation rate = [NO2 - -N] / ([NO2 - -N]+[NO3 - -N])

[0084] The results are as follows Figures 1-3 As shown:

[0085] Depend on Figure 1 As can be seen in Example 1, the nitrite accumulation rate increased with the extension of FA stress. Rapid startup of short-range nitrification (nitrite accumulation rate greater than 50%) was achieved on the third day (T5) of FA stress, demonstrating the feasibility of this startup method. However, when the influent FA concentration was reduced, the nitrite accumulation rate showed a decreasing trend, indicating that the short-range process startup method was not stable, possibly because the low FA concentration did not completely eliminate NOB in the system.

[0086] Depend on Figure 2 It can be seen that the nitrite nitrogen accumulation rate increases with the increase of FA stress time. Similarly, the rapid start-up of short-range nitrification is achieved on the third day (T5) of FA stress, indicating that this startup method is feasible. When the influent FA concentration is reduced, the system still maintains a high nitrite nitrogen accumulation rate, but after reducing the influent FA concentration, the nitrite nitrogen accumulation rate has a downward trend.

[0087] Depend on Figure 3 As can be seen, the nitrite accumulation rate increases with increasing FA stress time. Similarly, rapid startup of short-range nitrification was achieved on the third day (T5) of FA stress, demonstrating the feasibility of this startup method. When the influent FA concentration was reduced, the system still maintained a high nitrite accumulation rate, indicating that the startup method of Example 3 can both quickly start and have high process stability. However, the ammonia oxidation process was also significantly inhibited under this concentration stress, with an ammonia nitrogen removal rate of only 19.3%. Therefore, the ammonia nitrogen concentration should not be higher than 500 mg / L to avoid irreversible damage to AOB.

[0088] In summary, the present invention realizes the rapid start of in situ short-range nitrification and denitrification based on the differential sensitivity of AOB and NOB to high-concentration FA stress, and the nitrite nitrogen accumulation rate can be greater than 50% within 3 days of stress.

[0089] Comparative Example 1

[0090] The pollutant removal performance of the short-cut process and the full-cut process of Example 3 were compared by running the full-cut nitrification and denitrification process simultaneously. After the short-cut process was started according to the method described in Example 3, it was run continuously for 18 days. At the same time, the full-cut nitrification and denitrification process was started and run simultaneously for 18 days.

[0091] The full nitrification and denitrification process: the carbon-nitrogen ratio is set in the range of 6-7, the MLSS control range is 3500-4500 mg / L, the ammonia nitrogen concentration is 30-35 mg / L, the pH range is 7.3-7.8, and the DO range is controlled by the aeration pump in the range of 2.0-4.0 mg / L. After stable operation, the running cycle of the full nitrification and denitrification process is set as 280 min: 30 min of influent, 120 min of aeration, 60 min of anoxic, 30 min of aeration, 30 min of sedimentation, and 10 min of effluent. The short and full nitrification and denitrification processes are synchronously operated for 18 days.

[0092] The results, as shown in Figure 4 The average concentration of FA in the short process is 5.34 mg / L, while the average concentration of FA in the full process is 1.20 mg / L, indicating that the higher FA concentration in the short process continuously inhibits the activity of NOB.

[0093] Further analysis and comparison of the decontamination performance of the short and full nitrification and denitrification processes operated for 18 days show that Figures 5-6 After stable operation, the total nitrogen removal rates of the short and full processes are 82.99% and 62.21%, respectively; the nitrite nitrogen accumulation rates are 90.19% and 2.27%, respectively; the ammonia nitrogen removal rates are 94.69% and 87.71%, respectively; and the COD removal rates are 92.42% and 90.21%, respectively, proving that the decontamination performance of the short process is significantly better than that of the full process. In addition, the effluent of the short process can meet the first level A standard in the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant" (GB 18918-2002).

[0094] Comparative Example 2

[0095] A short nitrification and denitrification rapid start-up process, comprising the following steps:

[0096] Step 1, sludge inoculation and influent:

[0097] Take the sludge of the treatment unit of the aeration tank in the sewage plant, configure artificial simulated domestic sewage with an ammonia nitrogen concentration of about 40 mg / L and a COD concentration of about 280 mg / L, inoculate the seed sludge into the SBR reactor, introduce the sewage with a carbon-nitrogen ratio of 6-7 into the SBR reactor, control the sludge concentration MLSS in the reactor to be 6000-7000 mg / L, adjust the pH range to be 8.1-8.5 using NaHCO3, control the DO range to be 0.5-1.0 mg / L using the aeration pump, and monitor the pH and DO changes in the system in real time using the online pH and DO monitoring instrument;

[0098] Step 2, FA high-concentration stress stage:

[0099] The influent ammonia nitrogen concentration is increased to 500 mg / L, the influent FA stress concentration in the reactor is 90.71 mg / L, the DO range is controlled at about 0.5, the pH is about 8.5, and the aeration time is 20 h;

[0100] The influent ammonia nitrogen concentration is set to 400 mg / L, the influent FA concentration in the reactor is 79.72 mg / L, the pH range is about 8.5, the DO range is controlled at about 0.5, and the aeration time is 20 h;

[0101] Step 3, running phase:

[0102] The influent ammonia nitrogen concentration is further adjusted to about 40 mg / L, the aeration strategy (SBR running cycle is set to 280 min: influent 30 min, aeration 120 min, anoxic 60 min, aeration 30 min, sedimentation 30 min, and effluent 10 min), the DO range is strictly controlled at about 0.5, the pH range is 8.5, and the system is continuously run for 3 days.

[0103] The results are shown in Figure 7 Step 2, when the influent ammonia nitrogen concentration is increased to 500 mg / L, the ammonia nitrogen removal rate is only 0.71%, when the influent ammonia nitrogen concentration is set to 400 mg / L, the ammonia nitrogen removal rate is -1.17%, due to high concentration of FA stress, the system has appeared sludge bulking, the system is unstable, the ammonia oxidation process is completely inhibited in the continuous running phase, the sludge bulking is serious, and the system cannot be recovered.

[0104] Comparative Example 3

[0105] A short-cut nitrification and denitrification rapid start-up process, comprising the following steps:

[0106] Step 1, sludge inoculation and influent:

[0107] The sludge of the aeration tank treatment unit of a sewage plant is taken, artificial simulated domestic sewage with ammonia nitrogen concentration of about 40 mg / L and COD concentration of about 280 mg / L is configured to culture seed sludge, which is then inoculated into the SBR reactor, sewage with carbon-nitrogen ratio of 6-7 is introduced into the SBR reactor, the sludge concentration MLSS in the reactor is controlled to be 6000-7000 mg / L, NaHCO3 is used to adjust the pH range to be 8.1-8.5, aeration pump is used to control the DO range to be 0.5-1.0 mg / L, and the pH and DO online monitors are used to monitor the changes of pH and DO in the system in real time;

[0108] Step 2, FA medium concentration stress phase:

[0109] The influent ammonia nitrogen concentration was set to 100 mg / L, and the reactor was continuously operated for 2 days under FA stress concentration of 16.49 mg / L, aeration for 4 h, DO range controlled at about 0.5, and pH range adjusted to about 8.5 by NaHCO3. At this time, the nitrite nitrogen accumulation rate was 15.08%, and further denitrification was performed for 4 h.

[0110] Then the influent ammonia nitrogen concentration was increased to 200 mg / L, and the reactor was continuously operated for 3 days under FA stress concentration of 39.25 mg / L, aeration for 8 h, and pH range controlled at about 8.5. DO range was controlled at about 0.5 by an air flow meter. At this time, the nitrite nitrogen accumulation rate was 23.28%, and further denitrification was performed for 4 h.

[0111] The results are shown in Table 1. Figure 8 As shown in Table 1, although the nitrite nitrogen accumulation rate increased under the FA stress at this concentration, the nitrite nitrogen accumulation rate still did not exceed 50% after 5 days of stress, and the rapid start-up of shortcut nitrification-denitrification could not be achieved.

[0112] It can be understood that the present application is described by some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to the features and embodiments without departing from the spirit and scope of the present application. In addition, the features and embodiments can be modified to adapt to specific conditions and materials under the guidance of the present application without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope of the present application.

Claims

1. A short-cut nitrification and denitrification rapid start-up process, characterized in that: The following steps are involved: Step 1, sludge inoculation and water inflow: sludge rich in nitrifying bacteria is inoculated into the SBR reactor, and then sewage is introduced; Step 2, FA medium concentration stress: control the FA stress concentration of the reactor inlet water to 9-60 mg / L, and aerate for 4-12 hours; Step 3, FA high concentration stress: control the FA stress concentration of the influent in the reactor to 40-180 mg / L, aerate for 20-40 hours, and complete the short-range nitrification and denitrification startup process; Step 4, FA concentration stress: control the FA concentration of the influent in the reactor to 10-80 mg / L, and aerate for 8-20 hours; Step 5: Operation: Control the FA concentration of the influent in the reactor to 5-8 mg / L and operate with aeration; Wherein, the FA stress concentration of step 2 is less than the FA stress concentration of step 3, the FA stress concentration of step 3 is greater than the FA stress concentration of step 4, and the FA is free ammonia.

2. The rapid start-up process according to claim 1, wherein: In the FA medium concentration stress stage in step 2, the inlet ammonia nitrogen concentration is set to 100-300 mg / L; in the FA high concentration stress stage in step 3, the inlet ammonia nitrogen concentration is set to 300-900 mg / L; in the FA medium concentration stress stage in step 4, the inlet ammonia nitrogen concentration is set to 100-400 mg / L; in the operation stage in step 5, the inlet ammonia nitrogen concentration is set to 30-50 mg / L.

3. The rapid start-up process according to claim 1, wherein: The specific method of FA concentration stress in step 2 is: first control the FA stress concentration of the reactor inlet water to 18-20 mg / L, aerate for 3-5 hours, then control the FA stress concentration of the reactor inlet water to 35-40 mg / L, aerate for 7-9 hours.

4. The rapid start-up process according to claim 1, wherein: The specific method of FA high concentration stress in step 3 is: first control the FA stress concentration of the reactor inlet water to 45-100 mg / L, aerate for 18-22 hours, and then control the FA stress concentration of the reactor inlet water to 40-75 mg / L, aerate for 18-22 hours.

5. The rapid start-up process according to claim 1, wherein: The specific method of FA concentration stress in step 4 is as follows: first, the FA concentration of the influent water in the reactor is controlled to 25-40 mg / L, and aeration is carried out for 10-15 hours; then, the FA concentration of the influent water in the reactor is controlled to 13-36 mg / L, and aeration is carried out for 8-15 hours.

6. The rapid start-up process according to claim 1, wherein: In the FA medium concentration stress stage in step 2, the following steps are performed: first, the influent ammonia nitrogen concentration is set to 90-110 mg / L, aeration is performed for 3-5 hours, and then the influent ammonia nitrogen concentration is set to 190-210 mg / L, and aeration is performed for 7-9 hours; in the FA high concentration stress stage in step 3, the influent ammonia nitrogen concentration is first set to 490-510 mg / L, aeration is performed for 18-22 hours, and then the influent ammonia nitrogen concentration is set to 390-410 mg / L, and aeration is performed for 18-22 hours; in the FA medium concentration stress stage in step 4, the influent ammonia nitrogen concentration is first set to 190-210 mg / L, aeration is performed for 10-15 hours, and then the influent ammonia nitrogen concentration is set to 90-210 mg / L, and aeration is performed for 8-15 hours.

7. The rapid start-up process according to claim 1, wherein: During the entire process, the DO range is 0.3-1 mg / L, the pH range is 8-9, the residual ammonia nitrogen is 15-35 mg / L, and the carbon-nitrogen ratio is 5-8.

8. The rapid start-up process according to claim 7, characterized in that: During the entire process, the DO range was 0.5-0.7 mg / L, the pH range was 8-9, the residual ammonia nitrogen content was 20-30 mg / L, and the carbon-nitrogen ratio was 6-7.

9. The rapid start-up process according to claim 1, wherein: In step 1, the specific method of sludge inoculation and water inflow is: taking sludge from the aeration tank treatment unit of the sewage treatment plant, culturing it with artificially simulated domestic sewage and then inoculating it into the SBR reactor, introducing the sewage to be treated into the SBR reactor, and controlling the sludge concentration MLSS in the SBR reactor to be 6000-7000 mg / L.

10. The rapid start-up process according to claim 9, characterized in that: The carbon-nitrogen ratio of the sewage to be treated is 6-7, the ammonia nitrogen is 35-45 mg / L, and the COD is 250-300 mg / L.

11. The rapid start-up process according to any one of claims 1 to 10, characterized in that: The aeration operation strategy in the operation phase in step 5 is: the SBR operation cycle is set to 250-300 min, water inlet 20-40 min, aeration 110-130 min, anoxic 50-70 min, aeration 20-40 min, sedimentation 20-40 min, and water outlet 5-15 min.

12. The rapid start-up process according to claim 11, wherein: The aeration operation strategy is as follows: the SBR operation cycle is set to 280 min, with water inlet for 30 min, aeration for 120 min, anoxicity for 60 min, aeration for 30 min, sedimentation for 30 min, and water outlet for 10 min.

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