Device and method for realizing simultaneous denitrification and phosphorus removal by short-cut nitrification / anaerobic ammonia oxidation based on sludge side chlorination treatment

Abstract

The present application belongs to the field of sewage biological treatment technology, and particularly relates to a device and method for realizing simultaneous denitrification and phosphorus removal by short-cut nitrification / anaerobic ammonia oxidation based on sludge side chlorination treatment, comprising a water inlet tank, an AO reactor connected with the outlet of the water inlet tank, a secondary sedimentation tank connected with the outlet of the reactor, and a sludge chlorination pretreatment reactor connected with the outlet of the secondary sedimentation tank, wherein the AO reactor is divided into an anaerobic zone and an aerobic zone, the sludge chlorination pretreatment reactor is communicated with the aerobic zone through a first sludge return pump, and the secondary sedimentation tank is communicated with the anaerobic zone through a second sludge return pump, wherein the sludge is treated by side anoxic treatment, only part of the residual sludge is subjected to chlorination treatment, and the influence on anaerobic ammonia oxidation bacteria on the biofilm is avoided, so as to ensure the stable operation of the whole system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage biological treatment, and particularly relates to a device and method for realizing simultaneous denitrification and phosphorus removal based on sludge side chlorination treatment. BACKGROUND

[0002] Traditional sewage treatment processes are difficult to guarantee the removal of total nitrogen and phosphorus of low carbon-nitrogen ratio municipal sewage under the condition of no additional carbon source. Therefore, how to reduce the cost while improving the removal rate of pollutants has become the main challenge of low carbon-nitrogen ratio municipal sewage treatment. Anaerobic ammonia oxidation has become a research hotspot due to its autotrophic denitrification and no need to add external carbon source. If the stable operation of short-cut nitrification is realized, it can be coupled with anaerobic ammonia oxidation, thereby further saving aeration quantity and reducing energy consumption of sewage treatment.

[0003] In the traditional nitrification process, NH4 + -N is oxidized to NO2 - -N by ammonia-oxidizing bacteria (AOB), NO2 - -N is further oxidized to NO3 - -N by nitrite-oxidizing bacteria (NOB). AOB and NOB have similar physiological characteristics, and it is difficult to separate the two under normal operating conditions. How to inhibit NOB and enrich AOB is a big problem for realizing stable operation of short-cut nitrification. At present, the main research direction is to inhibit the activity of NOB by external strategy to realize short-cut nitrification. Sodium hypochlorite is a conventional disinfectant, which is usually used for disinfection of final effluent in sewage treatment, and sometimes used for sludge bulking control. In the past denitrification research, it has been found that bacteria in the two stages of nitrification reaction have different responses to inhibitors, thereby causing short-cut nitrification reaction. Therefore, in the process of sewage biological treatment, sodium hypochlorite solution is applied to side chlorination pretreatment of part of residual sludge to inhibit the activity of NOB, and then the pretreated sludge is returned to the main stream reactor to occur short-cut nitrification reaction, which is expected to greatly reduce the cost of sewage treatment. SUMMARY

[0004] The purpose of the application is to provide a device and method for realizing simultaneous denitrification and phosphorus removal based on sludge side chlorination treatment, which solves the deep denitrification and phosphorus removal technology of low C / N sewage.

[0005] To achieve the above purpose, the technical scheme adopted by the application is:

[0006] The device for realizing simultaneous denitrification and phosphorus removal by short-cut nitrification / anammox based on sludge side chlorination treatment, characterized by comprising a water inlet tank, an AO reactor connected with the outlet of the water inlet tank, a secondary sedimentation tank connected with the outlet of the reactor, and a sludge chlorination pretreatment reactor connected with the outlet of the secondary sedimentation tank, wherein the AO reactor is divided into an anaerobic zone and an aerobic zone, the sludge chlorination pretreatment reactor is communicated with the aerobic zone through a first sludge return pump, and the secondary sedimentation tank is communicated with the anaerobic zone through a second sludge return pump.

[0007] Further, the secondary sedimentation tank is communicated with the sludge chlorination pretreatment reactor through a third sludge return pump.

[0008] Further, the anaerobic zone is provided with a stirring device, the aerobic zone is internally provided with anammox biofilm filler, and the bottom of the aerobic zone is provided with an aeration head, and the sludge chlorination pretreatment reactor is provided with a stirring device and a dosing port.

[0009] The method for realizing simultaneous denitrification and phosphorus removal by short-cut nitrification / anammox based on sludge side chlorination treatment, comprising the following steps:

[0010] 1) Starting the system: the activated sludge of a municipal wastewater treatment plant is added to the AO reactor, so that the sludge concentration MLSS in the reactor is 2000-5000 mg / L, and meanwhile, the mature anammox biofilm filler is inoculated in the aerobic zone, and the filling ratio is 10%-20%;

[0011] 2) The operation is adjusted as follows:

[0012] a) The wastewater in the water inlet tank of the municipal wastewater is introduced into the anaerobic zone of the AO reactor through a water inlet pump, and meanwhile, the return sludge of the secondary sedimentation tank is also introduced, and the return ratio is 50%-100%; the phosphorus accumulating bacteria in the anaerobic zone absorb the organic matter in the raw water and store it in the form of PHAs in the organism, and meanwhile, a large amount of phosphorus is released;

[0013] b) The mixed liquid in the anaerobic zone is introduced into the aerobic zone of the AO reactor, and meanwhile, the chlorinated pretreated sludge is introduced in a time-keeping manner every day; the dissolved oxygen in the aerobic zone is maintained at 0.5-2 mg / L, the sludge age is 15 d, the hydraulic retention time is 8 h, the short-cut nitrification anammox reaction occurs in the aerobic zone, and meanwhile, the phosphorus accumulating bacteria absorb the phosphorus in the wastewater, so as to realize simultaneous denitrification and phosphorus removal;

[0014] c) The mixed liquid in the aerobic zone is introduced into the secondary sedimentation tank to complete the separation of sludge and water, the supernatant is discharged through a water outlet, part of the sludge at the bottom is returned to the anaerobic zone of the AO reactor, and part of the sludge is introduced into the sludge chlorination pretreatment reactor through a sludge return pump in a time-keeping manner every day; the amount of sludge introduced into the sludge chlorination pretreatment reactor each time is 2-5 L, and the remaining sludge is discharged through a sludge outlet, so as to ensure the growth of the phosphorus accumulating bacteria;

[0015] d) After the secondary sedimentation tank sludge enters the sludge chlorination pretreatment reactor, the effective chlorine concentration in the sludge chlorination pretreatment reactor is 40-100 mg / L by adding sodium hypochlorite solution into the sludge chlorination pretreatment reactor, and the sludge retention time is 8-24 h.

[0016] The basic principle is that oxidants, especially chlorate oxidants, have an impact on the nitrification reaction, and at a certain concentration, the NOB activity is significantly inhibited, while the AOB activity is not greatly affected. The disinfectants used in sewage treatment are mostly oxidants, which destroy enzymes in biological molecules through oxidation to achieve the purpose of killing bacteria. The biochemical characteristics of the two types of bacteria (AOB and NOB) involved in the nitrification reaction are different, so under the appropriate oxidation (bactericidal) action, selective inhibition of the more sensitive bacteria will occur, and the inhibition of NOB activity will be much greater than that of AOB Figure 2 The figure mainly reflects the specific situation of the activity of nitrifying bacteria (AOB and NOB) being inhibited after chlorination treatment at different effective chlorine concentrations. As can be clearly seen from the figure, for AOB, chlorination treatment has little effect on it; for NOB, chlorination treatment has a significant inhibitory effect on its activity. In the A / O process of the present application, anaerobic ammonia oxidation bacteria and nitrifying bacteria exist simultaneously in the entire reactor, and the volume of the main reactor is large. If sodium hypochlorite solution is directly added to the reactor, not only a large amount of addition is required, but also the anaerobic ammonia oxidation bacteria on the biofilm will be inhibited. Therefore, a side pretreatment system is applied to chlorinate part of the concentrated residual sludge, which not only reduces the addition amount of sodium hypochlorite solution but also effectively selectively inhibits the activity of NOB; then the pretreated sludge is backflowed to the aerobic zone of the main reactor, thereby ensuring the stable operation of the shortcut nitrification reaction and avoiding the inhibition of the anaerobic ammonia oxidation bacteria on the biofilm.

[0017] The process for treating sewage is as follows: municipal sewage and the return sludge of the secondary sedimentation tank enter the anaerobic zone of the AO reactor, where the phosphorus accumulating bacteria absorb a large amount of easily degradable organic matter and store it in the form of PHAs in their bodies, while releasing a large amount of phosphorus; the mixed liquor in the anaerobic zone and the sludge pretreated by chlorination added at regular time enter the aerobic zone, where the shortcut nitrification and anaerobic ammonia oxidation reactions occur, and the phosphorus accumulating bacteria absorb the remaining phosphorus; the mixed liquor in the aerobic zone enters the secondary sedimentation tank to complete the separation of sludge and water, the supernatant is discharged through the drainage port, part of the sludge at the bottom is returned to the anaerobic zone, part of it enters the sludge chlorination pretreatment reactor, and the rest is discharged through the sludge discharge port; part of the residual sludge is pretreated by chlorination on the side to effectively inhibit the growth of nitrite oxidizing bacteria, and then is backflowed to the aerobic zone, thereby realizing and maintaining the stable operation of the system shortcut nitrification, so that the anaerobic ammonia oxidation reaction can also be stably carried out.

[0018] The present application has the following advantages:

[0019] 1. The present application side oxygen deficiency treatment sludge, only to part of the remaining sludge chlorination treatment, avoid the influence on the anaerobic ammonia oxidation bacteria on the biofilm, so as to ensure the stable operation of the whole system;

[0020] 2. The present application adopts sodium hypochlorite solution chlorination treatment sludge, under the action of oxidation sterilization, selective inhibition of more sensitive NOB, so as to cause short nitrification reaction, realize stable operation;

[0021] 3. The present application is inoculated with anaerobic ammonia oxidation biofilm filler, and when the discharge of residual sludge is used to achieve the purpose of phosphorus removal, the loss of anaerobic ammonia oxidation bacteria is avoided, and the anaerobic ammonia oxidation activity in the system is ensured;

[0022] 4. The present application couples short nitrification, anaerobic ammonia oxidation and biological phosphorus removal, realizes simultaneous denitrification and phosphorus removal, saves carbon source and aeration quantity, and reduces the energy consumption of sewage treatment. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the device structure schematic diagram of the present application based on sludge side chlorination treatment to realize short nitrification / anaerobic ammonia oxidation denitrification and simultaneous phosphorus removal.

[0024] Figure 2 It is the influence of different effective chlorine concentration on nitrifying bacteria activity.

[0025] The specific calculation formula is:

[0026] Wherein, y is the inhibition degree, R0 is the initial nitrifying bacteria activity (mgN / (gVSS·h)), Rx is the nitrifying bacteria activity after chlorination treatment under different effective chlorine concentration (mgN / (gVSS·h)) DETAILED DESCRIPTION

[0027] As shown in the figure, a device for realizing short nitrification / anaerobic ammonia oxidation denitrification and simultaneous phosphorus removal based on sludge side chlorination treatment: provided with municipal sewage inlet tank 1, AO reactor 2, secondary sedimentation tank 3, sludge chlorination pretreatment reactor 4; wherein the AO reactor 2 is divided into anaerobic zone 2.1 and aerobic zone 2.2, and the aerobic zone 2.2 is provided with anaerobic ammonia oxidation biofilm filler 2.5; the sewage in the municipal sewage inlet tank 1 enters the AO reactor 2 through the water inlet pump 1.1, and then flows through the anaerobic zone 2.1 and the aerobic zone 2.2, and enters the secondary sedimentation tank 3; the secondary sedimentation tank 3 is connected with the anaerobic zone 2.1 and the sludge chlorination pretreatment reactor 4 through the second sludge return pump 3.3 and the third sludge return pump 3.2 respectively; the sludge chlorination pretreatment reactor 4 is connected with the aerobic zone through the first sludge return pump 4.3.

[0028] The treatment process of municipal wastewater in the process is as follows: the municipal wastewater and the return sludge of the secondary sedimentation tank enter the anaerobic zone of the AO reactor, the phosphorus accumulating organisms absorb a large amount of easily degradable organic matter in the anaerobic zone and store it in the form of PHAs in their organisms, and release a large amount of phosphorus at the same time; the mixed liquid in the anaerobic zone and the sludge pretreated by chlorination added at a fixed time every day enter the aerobic zone, short-cut nitrification and anammox reaction are carried out in the aerobic zone, and the phosphorus accumulating organisms absorb the remaining phosphorus; the mixed liquid in the aerobic zone enters the secondary sedimentation tank, the separation of sludge and water is completed, the supernatant is discharged through the water outlet, part of the sludge at the bottom is returned to the anaerobic zone, part of the sludge enters the sludge chlorination pretreatment reactor, and the rest is discharged through the sludge outlet; part of the residual sludge is pretreated by side chlorination, which effectively inhibits the growth of nitrite oxidizing bacteria, and then is returned to the aerobic zone, so that the system short-cut nitrification is stable, and the anammox reaction can also be stably carried out.

[0029] The specific test water is simulated municipal wastewater, and the water quality is as follows: the COD concentration is 230 mg / L; the NH4 + -N concentration is 60 mg / L, the NO2 - -N≤0.5 mg / L, the NO3 - -N≤0.5 mg / L, P=6 mg / L, CaCl2·2H2O=14 mg / L, MgSO4·7H2O=90 mg / L. The test system is shown in Figure 1 Each reactor is made of organic glass, and the effective volume of the AO reactor is 24 L.

[0030] The specific operation is as follows:

[0031] 1) Start the system: add the activated sludge of the municipal wastewater treatment plant to the AO reactor 2, so that the sludge concentration MLSS in the reactor is 2000-5000 mg / L, and inoculate the mature anammox biofilm filler 2.5 in the aerobic zone 2.2, and the filling ratio is 10%-20%.

[0032] 2) The adjustment operation during operation is as follows:

[0033] a) The wastewater in the wastewater tank 1 enters the anaerobic zone 2.1 of the AO reactor 2 through the water pump 1.1, and the return sludge of the secondary sedimentation tank 3 also enters at the same time, and the return ratio is 50%-100%. The phosphorus accumulating organisms in the anaerobic zone absorb the organic matter in the raw water and store it in the form of PHAs in their organisms, and release a large amount of phosphorus at the same time.

[0034] b) the mixed liquor in the anaerobic zone 2.1 enters the aerobic zone 2.2 of the AO reactor 2, and the chlorinated sludge added at a fixed time every day also enters the aerobic zone 2.2, the dissolved oxygen in the aerobic zone 2.2 is kept at about 0.5 mg / L-2 mg / L, the sludge age is 15 d, and the hydraulic retention time is 8 h. The short-cut nitrification and anammox reaction occurs in the aerobic zone, and the phosphorus-accumulating bacteria absorb the residual phosphorus, so that the simultaneous nitrogen and phosphorus removal is realized.

[0035] c) the mixed liquor in the aerobic zone 2.2 enters the secondary sedimentation tank 3, and the sludge-water separation is completed, the supernatant is discharged through the water outlet 3.4, and part of the sludge at the bottom is returned to the anaerobic zone 2.1 of the AO reactor 2, and part of the sludge is returned to the sludge chlorination pretreatment reactor 4 at a fixed time every day through the third sludge return pump 3.2, the amount of sludge entering the sludge chlorination pretreatment reactor 4 each time is 2-5 L, the remaining sludge is discharged through the sludge outlet 3.1, and the growth of the phosphorus-accumulating bacteria is ensured.

[0036] d) after part of the sludge in the secondary sedimentation tank 3 enters the sludge chlorination pretreatment reactor 4, sodium hypochlorite solution is added to the sludge chlorination pretreatment reactor 4, so that the effective chlorine concentration in the reactor is 40-100 mg / L, and the sludge retention time is 8-24 h.

[0037] The test results show that after stable operation, the final effluent COD of the reactor is 30-50 mg / L, NH4 + -N<3 mg / L, P<0.5 mg / L, NO2 - -N<1 mg / L, NO3 - -N<3 mg / L; after the floc sludge in the aerobic tank is taken out, the activity of short-cut nitrification is measured separately, and the NO2 - -N accumulation rate is as high as more than 90%.

[0038] The device and method for realizing short-cut nitrification / anammox simultaneous nitrogen and phosphorus removal based on sludge side chlorination treatment can be widely applied to municipal sewage.

Claims

1. A method for simultaneous denitrification and phosphorus removal based on short-cut nitrification / anaerobic ammonia oxidation (ANAMMOX) by sludge side chlorination treatment, characterized in that, The phosphorus removal device comprises a water inlet tank, an AO reactor connected with the outlet of the water inlet tank, a secondary sedimentation tank connected with the outlet of the reactor, and a sludge chlorination pretreatment reactor connected with the outlet of the secondary sedimentation tank, wherein the AO reactor is divided into an anaerobic zone and an aerobic zone, the sludge chlorination pretreatment reactor is connected with the aerobic zone through a first sludge return pump, and the secondary sedimentation tank is connected with the anaerobic zone through a second sludge return pump; the method comprises the following steps: 1) starting the system: adding activated sludge from a municipal wastewater treatment plant to the AO reactor to make the sludge concentration in the reactor MLSS=2000-5000 mg / L, and inoculating the aerobic zone with mature anaerobic ammonia oxidation biofilm filler at a filling ratio of 10%-20%; 2) adjusting the operation as follows during operation: a) the wastewater in the water inlet tank of the municipal wastewater is pumped into the anaerobic zone of the AO reactor, and the return sludge of the secondary sedimentation tank is also introduced, with a return ratio of 50%-100%; the phosphorus accumulating bacteria in the anaerobic zone absorb the organic matter in the raw water and store it in the form of PHAs in their bodies, while releasing a large amount of phosphorus; b) the mixed liquid in the anaerobic zone enters the aerobic zone of the AO reactor, and the chlorinated pretreated sludge is also introduced at a constant time, with the dissolved oxygen in the aerobic zone maintained at 0.5-2 mg / L, the sludge age being 15 d, the hydraulic retention time being 8 h, and the short-cut nitrification and anaerobic ammonia oxidation reaction occurring in the aerobic zone, while the phosphorus accumulating bacteria absorb the phosphorus in the wastewater to achieve simultaneous denitrification and phosphorus removal; c) the mixed liquid in the aerobic zone enters the secondary sedimentation tank to complete the separation of sludge and water, the supernatant is discharged through the water outlet, and part of the sludge at the bottom is returned to the anaerobic zone of the AO reactor, and part of the sludge is introduced into the sludge chlorination pretreatment reactor at a constant time through the sludge return pump, with the amount of sludge introduced into the sludge chlorination pretreatment reactor being 2-5 L each time, and the remaining sludge being discharged through the sludge discharge port; d) after the sludge in the secondary sedimentation tank enters the sludge chlorination pretreatment reactor, sodium hypochlorite solution is added to the sludge chlorination pretreatment reactor to make the effective chlorine concentration in the reactor 40-100 mg / L, and the sludge retention time is 8-24 h.

2. The method according to claim 1, wherein the sludge is treated by side-stream chlorination. The secondary sedimentation tank is connected with the sludge chlorination pretreatment reactor through a third sludge return pump.

3. The method according to claim 1, wherein the sludge is treated by side-stream chlorination. The anaerobic zone is provided with a stirring device, the aerobic zone is internally provided with anaerobic ammonia oxidation biofilm filler, and the bottom of the aerobic zone is provided with an aeration head, and the sludge chlorination pretreatment reactor is provided with a stirring device and a dosing port.

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