Device and method for realizing shortcut nitrification-denitrification dephosphorization coupling of municipal domestic sewage under anoxic/aerobic alternate condition
Technical Field
The invention relates to a device and a method for realizing short-cut nitrification-denitrification dephosphorization of municipal domestic sewage under an anoxic/aerobic alternative condition, belonging to the technical field of biological sewage treatment.
Background
When the content of nutrient elements such as nitrogen and phosphorus in the water body is excessive, the nutrient elements exceed the self-cleaning capacity and the bearing capacity of the water body, so that the eutrophication of the water body is caused, algae and plankton grow excessively, the algae and plankton can secrete toxin in the growth process, and simultaneously, a large amount of DO can be consumed in the respiration process to ensure that the aquatic organisms die due to excessive anaerobism. The water quality of the water body is more turbid and malodorous, the stability of an ecosystem is reduced, the utilization of water resources is greatly influenced, and the development of industrial agriculture and animal husbandry is limited and even the physical health of human beings is threatened. At present, most sewage treatment plants in China have the problem that nitrogen and phosphorus cannot reach the standard simultaneously. In the practical application process of the traditional biological nitrogen and phosphorus removal process, the phenomenon that the nitrogen removal effect and the phosphorus removal effect cannot reach the optimal effect at the same time often occurs, and the problems of large consumption of aeration and carbon source, complex process, low nitrogen and phosphorus removal efficiency, high operation cost and the like exist.
The basic principle of the short-cut nitrification and denitrification nitrogen removal is that the growth of nitrite oxidizing bacteria is inhibited by controlling the conditions of temperature, dissolved oxygen, pH, sludge age and the like, so that the nitrification reaction is stopped when generating nitrite, and the nitrite is not further oxidized into nitrate but directly used as an electron acceptor for denitrification so as to remove nitrogen in the wastewater. The short-cut nitrification and denitrification can reduce the amount of oxygen demand (about 25%) and the organic carbon source (about 40%), thereby reducing the operation energy consumption and the operation cost.
The Enhanced Biological Phosphorus Removal (EBPR) technology can absorb an organic carbon source in sewage and synthesize an internal carbon source PHA (polyhydroxyalkanoate) to be stored in a body for releasing phosphorus at the same time in an anaerobic condition through the enriched PAOs and DPAOs in a sewage treatment system, then absorb the phosphorus by taking oxygen as an electron acceptor in an aerobic condition, and finally realize the removal of the phosphorus in the system by discharging phosphorus-rich excess sludge. Meanwhile, under the anoxic condition, the DPAOs can perform denitrification dephosphorization by taking nitrite nitrogen or nitrate nitrogen as electron acceptors. The denitrification dephosphorization realizes 'one carbon dual-purpose', and effectively realizes the synchronous removal of nitrogen and phosphorus and the saving of carbon sources. Furthermore, in EBPR systems, there is enrichment of GAOs at the same time as PAOs are enriched. The GAOs have a similar metabolic mechanism to that of the phosphorus accumulating bacteria, can absorb organic carbon sources in sewage under anaerobic conditions and store the organic carbon sources in vivo in the form of internal carbon source PHA, and can decompose the PHA productivity in vivo by using nitrite nitrogen or nitrate nitrogen as an electron acceptor for denitrification nitrogen under anoxic conditions.
The invention provides a novel process for realizing short-cut nitrification-denitrification dephosphorization of municipal domestic sewage under an anoxic/aerobic alternative condition. The short-cut nitrification and denitrification dephosphorization process can enable the short-cut nitrification process, the denitrification process, the dephosphorization process and the carbon removal process to occur in the same reactor at the same time, so that the required oxygen amount is greatly reduced, and the energy consumption is saved. The carbon sources can be effectively saved by the internal carbon stored by PAOs, DPAOs, GAOs and DGAOs in the anaerobic section when COD is consumed, so that the sewage with low C/N ratio can be better treated.
Disclosure of Invention
The invention aims to solve the technical problem of realizing short-cut nitrification and denitrification dephosphorization of urban domestic sewage under the anoxic/aerobic alternate condition and solve the problems that the carbon source is insufficient in the current sewage treatment, the effluent is not up to the first grade A, the treatment cost is high and the like, thereby realizing stable denitrification and dephosphorization. Firstly, pumping municipal domestic sewage into an SBR reactor through a peristaltic pump, absorbing an organic carbon source in the sewage by phosphorus removal bacteria (PAOs and DPAOs), glycan bacteria (GAOs) and denitrifying glycan bacteria (DGAOs) through anaerobic stirring, synthesizing an internal carbon source PHA (PHA) and storing the internal carbon source in a body, and simultaneously carrying out anaerobic phosphorus release by the phosphorus removal bacteria. Then entering a hypoxia/aerobiotic alternative stage, wherein periodic aeration is adopted in the process, and the aerobic stage carries out short-cut nitrification, endogenous denitrification of nitrite nitrogen, aerobic phosphorus absorption and denitrifying phosphorus removal in four periods in total. The anoxic section generates endogenous denitrification and denitrification dephosphorization. And after the anoxic/aerobic alternation is finished, the hypoxia aeration is continued, and the aeration is stopped by the real-time control of DO and pH. The alternation of low dissolved oxygen and anoxic/aerobic is beneficial to maintaining the stability of the short-cut nitrification. The PAOs, DPAOs, GAOs and DGAOs consume COD in the anaerobic section, and the stored internal carbon can effectively save carbon sources, so that the sewage with low C/N ratio can be better treated, the effect of enhancing biological phosphorus removal is achieved, and compared with the traditional nitrogen and phosphorus removal process, the process has the advantages of saving aeration amount and no need of additional carbon sources.
The purpose of the invention is solved by the following technical scheme:
device based on synchronous short-cut nitrification and denitrification dephosphorization is realized to oxygen deficiency/good oxygen in turn, its characterized in that: the device comprises a municipal sewage raw water tank (1), an anoxic/aerobic alternative shortcut nitrification and denitrification coupling dephosphorization SBR (2.3) connected with a water inlet valve (2.2) by a water inlet peristaltic pump (2.1), a stirrer (2.4) connected with the anoxic/aerobic alternative shortcut nitrification and denitrification coupling dephosphorization SBR (2.3) is connected with a stirring paddle (2.5), an aeration head (2.6), a gas flow meter (2.7), an air inlet valve (2.8), an air pump (2.9), a DO sensor (2.10), a pH sensor (2.11), a DO/pH tester (2.12), an overflow valve (2.13), a first drain valve (2.14), a second drain valve (2.15) and a sludge discharge valve (2.16). The anoxic/aerobic alternate shortcut nitrification coupled denitrification dephosphorization SBR (2.3) is connected with the sludge discharge tank (3) through a sludge discharge peristaltic pump (2.17); is connected with a drainage tank (4) through a drainage peristaltic pump (2.18).
The process comprises the following steps:
1) the reactor start-up phase: anoxic/aerobic alternative shortcut nitrification coupled denitrification dephosphorization SBR (2.3)
Short-cut nitrifying sludge and sludge containing PAOs, DPAOs, GAOs and DGAO in a domestic sewage reactor are treated by inoculation, and the volume ratio is 2: 1, the sludge concentration is controlled at 2500-3000 mg/L. Starting anoxic/aerobic alternate shortcut nitrification coupled denitrification dephosphorization SBR (2.3) under the condition of room temperature.
2) The operation of the operation process is adjusted as follows: domestic sewage in the raw urban sewage tank (1) is pumped into the anoxic/aerobic alternative shortcut nitrification and denitrification dephosphorization SBR (2.3) through a water inlet peristaltic pump (2.1). After water feeding is finished, anaerobic stirring is started for 2.5 hours by using anoxic/aerobic alternative short-cut nitrification and denitrification coupled with dephosphorization SBR (2.3), PAOs, DPAOs, GAOs and DGAOs absorb organic carbon sources in sewage through anaerobic stirring and synthesize an internal carbon source PHA to be stored in a body, and the PAOs and the DPAOs carry out anaerobic phosphorus release at the same time. Entering an anoxic/aerobic alternate stage, wherein the anoxic/aerobic alternate process adopts periodic first period of anoxic aeration for 2h, then anoxic stirring for 20min, and the subsequent three periods of anoxic aeration for 1h and anoxic stirring for 20min, wherein the total period is four.
In the aerobic stage, the PAOs performs aerobic phosphorus absorption while ammonia nitrogen in the inlet water is subjected to short-range nitrification and oxidation to nitrite nitrogen through aeration. The hypoxia aeration creates a hypoxia microenvironment, and the DPAOs perform denitrification dephosphorization by taking nitrite nitrogen as an electron acceptor and PHA stored in an anaerobic section as an electron donor. In the same way, the DGAOs take nitrite nitrogen as an electron acceptor and PHA stored in an anaerobic section as an electron donor to carry out endogenous denitrification. Further performing endogenous denitrification and denitrification dephosphorization in an anoxic stage by the same principle, and realizing the effect of deep denitrification and dephosphorization. In the anoxic stage of the anoxic/aerobic alternation, the activities of AOB and NOB are inhibited, but the recovery rate of AOB in the aerobic section is faster than that of NOB, and meanwhile, nitrite generated by the aerobic section is denitrified into nitrogen in the anoxic section, so that the substrates of NOB are reduced, and the anoxic/aerobic alternation is favorable for the stable maintenance of shortcut nitrification.
And (3) after the anoxic/aerobic alternation, continuously performing the anoxic aeration for 30-50 min, and controlling and stopping the aeration when a DO breakthrough point (dDO/dt is more than 1) is observed and a pH ammonia valley point (dpH/dt is more than or equal to 0) is real, wherein the aeration rate in the aeration process is adjusted by a gas flowmeter (2.7) to control the DO in the anoxic/aerobic alternation shortcut nitrification coupled denitrifying phosphorus removal SBR (2.3) to be 0.2-0.3 mg/L. Finally, after 20min of sedimentation, the wastewater enters a drainage stage, and after the aeration is stopped, the water is drained into a drainage tank (4) through a second drainage valve (2.15), wherein the drainage ratio is 60-70%.
Sludge needs to be discharged in the operation process of the anoxic/aerobic alternate shortcut nitrification and denitrification coupling dephosphorization SBR (2.3), a sludge discharge pump (2.17) is started and the sludge discharge time is controlled, so that the active sludge age in the anoxic/aerobic alternate shortcut nitrification and denitrification coupling dephosphorization SBR (2.3) is kept at 12-15 days.
A device and a method for realizing short-cut nitrification and denitrification dephosphorization of municipal domestic sewage under an anoxic/aerobic alternate condition have the following advantages:
1) the anoxic/aerobic alternation is favorable for the stability of short-cut nitrification, and the anoxic section strengthens denitrification and denitrification dephosphorization and further improves the removal rate of nitrogen and phosphorus.
2) The low oxygen and oxygen deficiency/aerobic alternation can effectively save energy, the carbon source in the anaerobic section storage is subjected to denitrification dephosphorization, the effect of one carbon and two purposes is achieved, no additional carbon source is needed, and the cost is saved.
3) The invention completes nitrogen and phosphorus removal in one SBR reactor, and has simple and easily controlled process and convenient operation.
Drawings
FIG. 1 is a schematic structural diagram of a device and a method for realizing synchronous short-cut nitrification and denitrification dephosphorization under anoxic/aerobic alternate conditions.
In fig. 1: 1 is a municipal sewage raw water tank, 2.1 is a water inlet peristaltic pump, 2.2 is a water inlet valve, 2.3 is anoxic/aerobic alternative shortcut nitrification coupled denitrification dephosphorization SBR, 2.4 is a stirrer, 2.5 is a stirring paddle, 2.6 is an aeration head, 2.7 is a gas flow meter, 2.8 is an air inlet valve, 2.9 is an air pump, 2.10 is a DO sensor, 2.11 is a pH sensor, 2.12 is a DO/pH tester, 2.13 is an overflow valve, 2.14 is a first drain valve, 2.15 is a second drain valve, 2.16 is a mud valve, 2.17 is a mud discharge peristaltic pump, 2.18 is a water discharge peristaltic pump, 3 is a mud discharge tank and 4 is a water discharge tank.
FIG. 2 is a timing diagram of the operation of short-cut nitrification-denitrification dephosphorization of municipal domestic sewage under anoxic/aerobic alternate conditions.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the drawings and examples.
As shown in figure 1, the device and the method for realizing short-cut nitrification-denitrification coupling dephosphorization of municipal domestic sewage under the anoxic/aerobic alternate condition are characterized in that: the device comprises a municipal sewage raw water tank (1), an anoxic/aerobic alternative shortcut nitrification and denitrification coupling dephosphorization SBR (2.3) connected with a water inlet valve (2.2) by a water inlet peristaltic pump (2.1), a stirrer (2.4) connected with the anoxic/aerobic alternative shortcut nitrification and denitrification coupling dephosphorization SBR (2.3) is connected with a stirring paddle (2.5), an aeration head (2.6), a gas flow meter (2.7), an air inlet valve (2.8), an air pump (2.9), a DO sensor (2.10), a pH sensor (2.11), a DO/pH tester (2.12), an overflow valve (2.13), a first drain valve (2.14), a second drain valve (2.15) and a sludge discharge valve (2.16). The anoxic/aerobic alternate shortcut nitrification coupled denitrification dephosphorization SBR (2.3) is connected with the sludge discharge tank (3) through a sludge discharge peristaltic pump (2.17); is connected with a drainage tank (4) through a drainage peristaltic pump (2.18).
The domestic sewage of the family district of Beijing university is used for investigating the nitrogen, phosphorus and carbon removal performance of the system, and the specific water quality of the raw water is as follows: COD concentration is 120-260 mg/L, NH4 +The concentration of-N is 50-75 mg/L, NO2 -Concentration of-N<0.1mg/L,NO3 -Concentration of-N<0.8mg/L, 5-7 mg/L of P concentration and 7-8 of pH. The test system is shown in figure 1, the reactor is made of organic glass, the anoxic/aerobic alternate shortcut nitrification is coupled with the denitrification dephosphorization SBR (2.3), and the effective volume is 10L.
The specific operation is as follows:
1) the reactor start-up phase: anoxic/aerobic alternative shortcut nitrification coupled denitrification dephosphorization SBR (2.3)
Short-cut nitrifying sludge and sludge containing PAOs, DPAOs, GAOs and DGAO in a domestic sewage reactor are treated by inoculation, and the volume ratio is 2: 1, the sludge concentration is controlled at 2500-3000 mg/L. Starting anoxic/aerobic alternate shortcut nitrification coupled denitrification dephosphorization SBR (2.3) under the condition of room temperature.
2) The operation of the operation process is adjusted as follows: domestic sewage in the raw urban sewage tank (1) is pumped into the anoxic/aerobic alternative shortcut nitrification and denitrification dephosphorization SBR (2.3) through a water inlet peristaltic pump (2.1). After water feeding is finished, anaerobic stirring is started for 2.5 hours by using anoxic/aerobic alternative short-cut nitrification and denitrification coupled with dephosphorization SBR (2.3), PAOs, DPAOs, GAOs and DGAOs absorb organic carbon sources in sewage through anaerobic stirring and synthesize an internal carbon source PHA to be stored in a body, and the PAOs and the DPAOs carry out anaerobic phosphorus release at the same time. Entering an anoxic/aerobic alternate stage, wherein the anoxic/aerobic alternate process adopts periodic first period of anoxic aeration for 2h, then anoxic stirring for 20min, and the subsequent three periods of anoxic aeration for 1h and anoxic stirring for 20min, wherein the total period is four. How the final aeration controls the stop reaction
In the aerobic stage, the PAOs performs aerobic phosphorus absorption while ammonia nitrogen in the inlet water is subjected to short-range nitrification and oxidation to nitrite nitrogen through aeration. The hypoxia aeration creates a hypoxia microenvironment, and the DPAOs perform denitrification dephosphorization by taking nitrite nitrogen as an electron acceptor and PHA stored in an anaerobic section as an electron donor. In the same way, the DGAOs take nitrite nitrogen as an electron acceptor and PHA stored in an anaerobic section as an electron donor to carry out endogenous denitrification. Further performing endogenous denitrification and denitrification dephosphorization in an anoxic stage by the same principle, and realizing the effect of deep denitrification and dephosphorization. In the anoxic stage of the anoxic/aerobic alternation, the activities of AOB and NOB are inhibited, but the recovery rate of AOB in the aerobic section is faster than that of NOB, and meanwhile, nitrite generated by the aerobic section is denitrified into nitrogen in the anoxic section, so that the substrates of NOB are reduced, and the anoxic/aerobic alternation is favorable for the stable maintenance of shortcut nitrification.
And (3) after the anoxic/aerobic alternation, continuously performing the anoxic aeration for 30-50 min, and controlling and stopping the aeration when a DO breakthrough point (dDO/dt is more than 1) is observed and a pH ammonia valley point (dpH/dt is more than or equal to 0) is real, wherein the aeration rate in the aeration process is adjusted by a gas flowmeter (2.7) to control the DO in the anoxic/aerobic alternation shortcut nitrification coupled denitrifying phosphorus removal SBR (2.3) to be 0.2-0.3 mg/L. Finally, after 20min of sedimentation, the wastewater enters a drainage stage, and after the aeration is stopped, the water is drained into a drainage tank (4) through a second drainage valve (2.15), wherein the drainage ratio is 60-70%.
Sludge needs to be discharged in the operation process of the anoxic/aerobic alternate shortcut nitrification and denitrification coupling dephosphorization SBR (2.3), a sludge discharge pump (2.17) is started and the sludge discharge time is controlled, so that the active sludge age in the anoxic/aerobic alternate shortcut nitrification and denitrification coupling dephosphorization SBR (2.3) is kept at 12-15 days.
The results of successive experiments show that: under the operating condition, the final effluent water average COD and NH4 +-N、NO2 - -N、NO3 - the-N, TN and TP are 34.51mg/L, 3.44mg/L, 5.06mg/L, 0.52mg/L, 9.02mg/L and 0.358mg/L respectively. The water quality indexes of the effluent all reach the first grade A standard of pollutant discharge Standard of urban Sewage treatment plant (GB 18918-2002).