CN112520937A

CN112520937A - Domestic wastewater treatment system and process

Info

Publication number: CN112520937A
Application number: CN202011187430.0A
Authority: CN
Inventors: 唐炜; 江慧如
Original assignee: Shanghai Yihu Environmental Engineering Technology Development Co ltd
Current assignee: Shanghai Yihu Environmental Engineering Technology Development Co ltd
Priority date: 2020-11-02
Filing date: 2020-11-02
Publication date: 2021-03-19

Abstract

The invention discloses a domestic wastewater treatment system and a process, which relate to the field of domestic wastewater treatment, and the technical scheme of the system comprises a primary treatment system, wherein the primary treatment system comprises a grid channel; the secondary treatment system comprises a nitrogen and phosphorus removal device, an ozonization device and a biological pond which are communicated with each other; the nitrogen and phosphorus removal device comprises a phosphorus content monitor, an anaerobic reaction tank, an anoxic reaction tank, an aerobic reaction tank and a sedimentation tank, wherein the phosphorus content monitor is arranged at a water inlet of the nitrogen and phosphorus removal device; a mixed liquid reflux device is arranged between the aerobic reaction tank and the anaerobic reaction tank; a sludge reflux device is arranged between the sedimentation tank and the anaerobic reaction tank; the technical effects are that the flexibility of the domestic wastewater treatment process is enhanced, the labor load is reduced, and the utilization efficiency of the treatment process is improved while the good treatment effect is ensured.

Description

Domestic wastewater treatment system and process

Technical Field

The invention relates to the field of wastewater treatment, in particular to a domestic wastewater treatment system and a domestic wastewater treatment process.

Background

Domestic wastewater is water used for washing in daily life of residents, the main sources of the domestic wastewater comprise kitchen wastewater, washing wastewater and bathing wastewater, only a small part of the domestic wastewater is treated, and most of the domestic wastewater is directly discharged into rivers, so that the rivers are seriously polluted.

The water quality characteristics of the domestic wastewater from different sources have difference, for example, table 1 is the water quality composition table of the domestic wastewater in a certain area of Jiangzhe area; as can be seen from the table, the total phosphorus content of the kitchen wastewater is lower, and the phosphorus content of the washing wastewater and the bathing wastewater is higher than that of the kitchen wastewater; the typical characteristic of domestic wastewater is that the drainage time of various types of wastewater is unstable, and in three dining time periods of morning, noon and evening, the main source of the domestic wastewater is kitchen wastewater, and at the moment, the phosphorus content in the domestic wastewater is lower.

TABLE 1 Water quality composition table of domestic wastewater in certain area of Jiangzhe area

Generally, the water quality of a certain wastewater is comprehensively judged by pH, turbidity, biochemical oxygen demand BOD, chemical oxygen demand COD, total phosphorus TP and total nitrogen TN. Wherein, PH judges the acid-base degree of the wastewater; determining the turbidity degree of the wastewater; biochemical oxygen demand BOD and chemical oxygen demand COD can comprehensively judge the content of organic pollutants in the wastewater; total phosphorus TP represents the total amount of phosphorus-containing contaminants in the wastewater; total nitrogen TN indicates the total amount of nitrogen-containing contaminants in the wastewater.

The monitoring method of total phosphorus TP is phosphomolybdic acid colorimetry; the monitoring method of total nitrogen TN is a salicylic acid spectrophotometry; the monitoring method of chemical oxygen demand COD is potassium dichromate method, and the monitoring method of biochemical oxygen demand BOD is potassium permanganate method.

The existing domestic wastewater treatment method is characterized in that domestic wastewater is adjusted and mixed and then treated, the water quality difference of domestic wastewater in different time periods is ignored, the flexibility and the flexibility of a treatment device are poor, and the treatment efficiency is low.

Disclosure of Invention

The invention aims to provide a domestic wastewater treatment system which has the advantages of simple and convenient treatment structure and flexible treatment modes for different water quality conditions.

The technical purpose of the invention is realized by the following technical scheme:

a domestic wastewater treatment system comprises

The primary treatment system comprises a grating channel;

the secondary treatment system comprises a nitrogen and phosphorus removal device, an ozonization device and a biological pond which are communicated with each other;

the nitrogen and phosphorus removal device comprises a phosphorus content monitor, an anaerobic reaction tank, an anoxic reaction tank, an aerobic reaction tank and a sedimentation tank, wherein the phosphorus content monitor is arranged at a water inlet of the nitrogen and phosphorus removal device, and water outlets of the anoxic reaction tank and the anaerobic reaction tank are communicated with the aerobic reaction tank; a mixed liquid reflux device is arranged between the aerobic reaction tank and the anaerobic reaction tank; the water outlet of the aerobic reaction tank is communicated with the sedimentation tank, and a sludge reflux device is arranged between the sedimentation tank and the anaerobic reaction tank; a certain concentration value of the phosphorus content is preset in the phosphorus content detector, and when the total phosphorus TP in the wastewater is greater than the preset value, the wastewater enters an anaerobic reaction tank; otherwise, the wastewater enters an anoxic reaction tank.

Through adopting above-mentioned technical scheme, can be according to the difference of the total phosphorus content of handling waste water, select the most appropriate processing apparatus, under the prerequisite of guaranteeing the treatment effect, choose the most economical processing mode for use, the system regulation and control is more nimble.

Further setting: the phosphorus content monitor comprises a screen, a photolysis chamber, a microfluid mixing chamber, a detection chamber and a control chamber which are communicated with each other; inside the waste water pipeline before the photodissociation cavity was located to the screen cloth, be equipped with the reductant of slow flow in the microfluid mixing chamber, install ultraviolet monochromatic light source in the measuring chamber.

By adopting the technical scheme, the phosphorus content detector can quickly measure the total phosphorus concentration in the wastewater at the moment, and then compares the total phosphorus concentration with the preset value, so that the relation between the total phosphorus content and the preset value at the moment is conveniently and quickly judged, and the effect of real-time monitoring is achieved.

Further setting: the phosphorus content concentration preset value of the phosphorus content detector is 2 mg/L.

By adopting the technical scheme, when the total phosphorus content in the wastewater is more than 2mg/L, the treatment load of the wastewater can be increased by adopting the anaerobic reaction tank process, and the treatment load is set to be 2mg/L, so that different treatment methods can be well adopted for domestic wastewater with different water qualities.

Further setting: the water inlets of the anoxic reaction tank and the anaerobic reaction tank are respectively provided with an electromagnetic valve, and the electromagnetic valves are electrically connected with the control chamber.

By adopting the technical scheme, the control room of the phosphorus content monitor can automatically select the use of the follow-up device in time after judgment, thereby reducing the labor intensity.

Further setting: the ozonization device comprises an ozone electrolysis device, an ozone pipe and an ozone mixing tank, wherein the ozone mixing tank is communicated with the sedimentation tank, and the ozone electrolysis device is communicated with the ozone mixing tank through the ozone pipe.

Through adopting above-mentioned technical scheme, ozone electrolytic device can fast deionize the air and generate ozone, and ozone takes place oxidation reaction in the ozone blending tank, gets rid of the organic matter in the aquatic in the twinkling of an eye, reduces biochemical oxygen demand BOD and chemical oxygen demand COD, also can reduce the turbidity and the stink of waste water simultaneously.

Further setting: and a grid is arranged in the grid channel.

By adopting the technical scheme, the grating can play a role of mechanical slag removal, and remove insoluble residues such as long fibers, dead leaves and the like in the wastewater.

Another object of the present invention is to provide a domestic wastewater treatment process which has the advantage of flexibility between processes.

a domestic wastewater treatment system comprising the steps of:

s01: domestic wastewater is collected to the grid channel through a wastewater pipeline to finish primary filtration;

s02: the domestic wastewater flows through the phosphorus content monitor through the water outlet pipeline of the grid channel, and the total phosphorus concentration in the domestic wastewater at the moment is monitored;

s03: when the phosphorus content monitor judges that the total phosphorus TP in the drained water is less than or equal to 2mg/L, adopting an anoxic-aerobic-anoxic-aerobic process;

s04: when the phosphorus content monitor judges that the total phosphorus TP in the drained water is more than 2mg/L, an anaerobic-aerobic-anoxic-aerobic process is adopted;

s05: a mixed liquid reflux device is arranged between the aerobic reaction tank and the anoxic reaction tank;

s06: domestic wastewater flows into a sedimentation tank from an aerobic reaction tank;

s07: a sludge reflux device is arranged between the sedimentation tank and the anaerobic reaction tank;

s08: domestic wastewater flows into the ozone mixing pipe from the sedimentation tank;

s09: the domestic wastewater flows into the biological pond through the ozone mixing pipe;

s10: domestic wastewater is discharged from the biological pond to the environment.

By adopting the technical scheme, the water quality differences of domestic wastewater in different time periods can be well distinguished, and a more appropriate treatment process is adopted for the domestic wastewater with different water qualities, so that the maximum utilization rate of the treatment process is achieved, the treatment efficiency is improved, and the treatment cost is reduced.

Further setting: the reflux ratio of the mixed solution in the mixed solution reflux unit was 250%.

By adopting the technical scheme, under the reflux ratio, the BOD removal rate of the anoxic reaction tank and the aerobic reaction tank is between 80% and 85%, and the TN removal rate is between 75% and 80%, so that the removal effects of the anoxic reaction tank and the aerobic reaction tank are good.

Further setting: the sludge reflux ratio of the sludge reflux device is 50 percent.

By adopting the technical scheme, the good removal effect of TN and TP can be ensured at the same time under the reflux proportion.

Further setting: the phosphorus content monitor comprises a screen, a photolysis chamber, a microfluid mixing chamber, a detection chamber and a control chamber which are communicated with each other; the screen is arranged in a waste water pipeline in front of the photolysis chamber, a slow-flowing reducing agent is arranged in the microfluid mixing chamber, and an ultraviolet monochromatic light source is arranged in the detection chamber; the phosphorus content detector adopts a phosphomolybdic acid colorimetric method to detect the total phosphorus content.

By adopting the technical scheme, the phosphorus content detector can quickly measure the total phosphorus concentration in the wastewater at the moment by utilizing a phosphomolybdic acid colorimetric method of a national standard detection method, and then the total phosphorus concentration is compared with a preset value, so that the relation between the total phosphorus content and the preset value at the moment is conveniently and quickly judged, and the effect of real-time monitoring is achieved.

In conclusion, the invention has the following beneficial effects:

according to different characteristics of total phosphorus TP content of domestic wastewater in different time periods, the total phosphorus content of the domestic wastewater to be treated is monitored in real time through a phosphorus content detector, then 2mg/L is taken as a boundary point, the domestic wastewater with the total phosphorus TP less than or equal to 2mg/L and the total phosphorus TP greater than 2mg/L is judged, a subsequent treatment process is automatically changed, the flexibility of the domestic wastewater treatment process is greatly enhanced, the labor burden is reduced, and the utilization efficiency of the treatment process is improved while a good treatment effect is ensured.

Drawings

FIG. 1 is a schematic view of a domestic wastewater treatment process;

FIG. 2 is a system diagram of a domestic wastewater treatment process;

FIG. 3 is a system schematic of a phosphorus content monitor of a domestic wastewater treatment process;

in the figure, the position of the upper end of the main shaft,

1. a primary processing system; 2. a secondary processing system; 20. an ozonization device;

101. a grid channel; 201 an anoxic reaction tank; 202. an aerobic reaction tank; 203. an anaerobic reaction tank; 204. a sedimentation tank; 205. a mixed liquid reflux device; 206. a sludge reflux device; 207. an ozone generator; 208. an ozone tube; 209. an ozone mixing tank; 210. a biological pond; 211. a phosphorus content monitor;

2111. screening a screen; 2112. a photolysis chamber; 2113. a microfluidic mixing chamber; 2114. a detection chamber; 2115. and a control room.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

First preferred embodiment:

a domestic wastewater treatment process comprises a grid channel 101, a nitrogen and phosphorus removal device, an ozonization device 20 and a biological pond 210 in sequence according to the water inlet and outlet sequence of domestic wastewater.

The process carries out different treatment processes on domestic wastewater with total phosphorus TP less than or equal to 2mg/L and domestic wastewater with total phosphorus TP more than 2 mg/L.

As shown in fig. 1, the first stage treatment includes a grid channel 101, and the grid channel 101 is provided with a grid which is used for mechanical slag removal and can remove insoluble residues such as long fibers and dead leaves in the wastewater.

Secondly, secondary advanced treatment, which comprises a nitrogen and phosphorus removal device, an ozonization device 20 and a biological pond 210;

the nitrogen and phosphorus removal device comprises a phosphorus content monitor 211, an anaerobic reaction tank 203, an anoxic reaction tank 201, an aerobic reaction tank 202 and a sedimentation tank 204; a water inlet of the nitrogen and phosphorus removal device is provided with a phosphorus content monitor 211, the phosphorus content monitor 211 sequentially comprises a screen 2111, a photolysis chamber 2112, a microfluid mixing chamber 2113, a monitoring chamber and a control chamber 2115 according to the wastewater flow direction, wherein the control chamber 2115 is electrically connected with electromagnetic valves of water inlets of the anoxic reaction tank 201 and the anaerobic reaction tank 203, and water outlets of the anoxic reaction tank 201 and the anaerobic reaction tank 203 are communicated with the aerobic reaction tank 202 through a sewage pipe; a mixed liquor reflux device 205 is arranged between the aerobic reaction tank 202 and the anaerobic reaction tank 203; the water outlet of the aerobic reaction tank 202 is communicated with a sedimentation tank 204 through a sewage pipe, and a sludge reflux device 206 is arranged between the sedimentation tank 204 and the anaerobic reaction tank 203; the domestic wastewater flows out of the grid channel 101 and then enters the nitrogen and phosphorus removal device for nitrogen and phosphorus removal treatment.

The specific nitrogen and phosphorus removal process flow is as follows:

according to the formula of denitrification theory, eta is (R + R)/(1+ R + R),

wherein R represents the reflux ratio of the mixed liquid;

r represents a sludge reflux ratio;

the difference of the reflux ratio R of the mixed liquor can affect the nitrogen removal effect of the nitrogen and phosphorus removal device, when R is too large, the internal reflux consumes large energy and can damage the anoxic environment, influence the COD concentration and further affect the nitrogen removal effect, and when the reflux ratio is between 200% and 300%, the overall removal effect is the best, so that the reflux ratio of the mixed liquor in the process is set to be 250%; in the case of a fixed reflux ratio of the mixed liquor, the larger the reflux of the sludge, the higher the removal rate of nitrogen, but the higher the reflux ratio of the sludge, the lower the removal rate of phosphorus, and in this process, when total phosphorus TP > 1.2mg/L, the wastewater passes through the anaerobic reaction tank 203, so the reflux ratio of the sludge in this process is set to 50%.

As shown in FIG. 3, a phosphorus content monitor 211 is provided at the water inlet of the denitrification and dephosphorization apparatus for real-time monitoring the total phosphorus content of the wastewater flowing in. When the domestic wastewater flows through the phosphorus content monitor 211, domestic wastewater with a volume of 2ml-3ml enters the flow tube after impurities are filtered by the screen 2111, then enters the photolysis chamber 2112 through the flow tube, an organic phosphorus is converted into an inorganic phosphorus by a photocatalytic reaction in the photolysis chamber 2112, then the inorganic phosphorus flows into the microfluidic mixing chamber 2113 through the flow tube, a monitoring reagent is arranged in the microfluidic mixing chamber to be mixed and developed with the wastewater to be detected, the wastewater to be detected after the color development reaction flows into the monitoring chamber, the absorbance at the maximum absorption wavelength of 710nm is tested in the monitoring chamber, the absorbance in the control chamber 2115 is rapidly compared with the absorbance at the preset total phosphorus concentration of 1.2mg/L, and whether the total phosphorus concentration at the moment is more than 2mg/L or not is judged.

As shown in fig. 1, when the phosphorus content monitor 211 judges that the total phosphorus TP in the discharged water is less than or equal to 2mg/L, the control chamber 2115 electrically connects and opens the electromagnetic valve of the anoxic reaction tank 201, and at the same time, the electromagnetic valve of the water inlet of the anaerobic reaction tank 203 is in a closed state, and at this time, an anoxic-aerobic-anoxic-aerobic process is adopted;

domestic wastewater enters the anoxic reaction tank 201 through a sewage pipe; the denitrifying bacteria in the anoxic reaction tank 201 utilize organic matters in the wastewater as a carbon source to reduce a large amount of NO3-N and NO2-N in the wastewater into N2 to be released into the air, so that the total nitrogen content in the wastewater is greatly reduced, and most of denitrification work is completed; the water outlet of the anoxic reaction tank 201 is communicated with the aerobic reaction tank 202, and the wastewater flows out of the anoxic reaction tank 201 and then enters the aerobic reaction tank 202; in the aerobic reaction tank 202, organic matters are biochemically degraded by microorganisms, organic nitrogen is ammoniated and then is nitrified, so that the concentration of NH3-N is obviously reduced, and phosphorus is also reduced at a higher speed due to excessive uptake of phosphorus accumulating bacteria; the water outlet of the aerobic reaction tank 202 is provided with a mixed liquor reflux device 205, the reflux proportion is 250%, the mixed liquor returns to the anoxic reaction tank 201 through the reflux device, organic matters in the mixed liquor provide a carbon source for anoxic reaction, and the mixed liquor is subjected to secondary nitrogen and phosphorus removal.

When the phosphorus content monitor 211 judges that the total phosphorus TP in the discharged water is more than 2mg/L, the control chamber 2115 electrically connects and opens the electromagnetic valve of the anaerobic reaction tank 203, and simultaneously makes the electromagnetic valve of the water inlet of the anoxic reaction tank 201 in a closed state, and at the moment, adopts the anaerobic-aerobic-anoxic-aerobic process;

the domestic wastewater enters an anaerobic reaction tank 203 through a sewage pipe; the dissolved organic matters in the anaerobic reaction tank 203 are absorbed by microbial cells to reduce the BOD concentration in the wastewater, NH3-N is partially removed due to the synthesis of the cells to reduce the NH3-N concentration in the wastewater and release phosphorus to increase the phosphorus concentration in the wastewater; the water outlet of the anaerobic reaction tank 203 is communicated with the aerobic reaction tank 202, organic matters are biochemically degraded by microorganisms in the aerobic reaction tank 202, organic nitrogen is ammoniated and then is nitrified, so that the concentration of NH3-N is obviously reduced, and phosphorus is also reduced at a higher speed due to excessive uptake of phosphorus accumulating bacteria; a mixed liquor reflux device 205 is arranged at a water outlet of the aerobic reaction tank 202, part of the wastewater flows back to the anoxic reaction tank 201 through the mixed liquor reflux device 205, organic matters in the mixed liquor provide a carbon source for anoxic reaction, and the mixed liquor is subjected to secondary nitrogen and phosphorus removal.

The water outlet of the aerobic reaction tank 202 is connected with a sedimentation tank 204, wastewater enters the sedimentation tank 204 from the aerobic reaction tank 202 for sedimentation, activated sludge is settled at the bottom of the tank, a sludge reflux device 206 is arranged between the sedimentation tank 204 and the anaerobic reaction tank 203, the sludge reflux proportion is 50%, and part of wastewater flows back to the anaerobic tank through the sludge reflux device 206 to provide microbial strains for the anaerobic tank.

The ozone purification tank comprises an ozone generator 207, an ozone pipe 208 and an ozone mixing tank 209; the water outlet of the sedimentation tank 204 is communicated with an ozone mixing tank 209 through a sewage pipe, and an ozone generator 207 is communicated with the ozone mixing tank 209 through an ozone pipe 208; the water outlet of the ozone mixing tank 209 is communicated with the biological tank 210 through a sewage pipe;

air in the ozone generator 207 is ionized to simultaneously generate high-concentration plasma and electrons, the electrons and the ions collide and accelerate under the action of an electric field force, oxygen molecules are instantly decomposed into monatomic oxygen, the monatomic oxygen and the oxygen molecules are combined to form ozone within a very short time, and the ozone enters the ozone mixing tube through the ozone tube 208;

the wastewater is discharged from a water outlet of the secondary sedimentation tank and enters an ozone mixing pipe, and the wastewater is ozonized in the ozone mixing pipe; ozone can generate active monatomic oxygen, hydroxyl, ozone ion groups, oxide ion groups and the like with strong oxidation effect in water, can effectively remove organic matters in water through oxidation reaction, reduce Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), and simultaneously can reduce turbidity and odor of wastewater;

because ozonization byproducts can be generated by ozone purified water, the water outlet of the ozone purification device is communicated with the biological pool 210 through a sewage pipe, wastewater enters the biological pool 210 after being subjected to pre-ozonization, the byproducts generated by ozone are removed through the adsorption effect of biological activated carbon in the biological pool 210, and finally the whole set of water purification process is completed and discharged into the environment.

Extracting a water sample of final drainage, and performing comprehensive water quality monitoring on the treated domestic wastewater according to a determination method in a national standard determination method; monitoring, the biochemical oxygen demand BOD of the finally discharged treated domestic wastewater is less than or equal to 10mg/L, the chemical oxygen demand COD is less than or equal to 50mg/L, the total phosphorus TP is less than or equal to 0.5mg/L, and the total nitrogen TN is less than or equal to 15mg/L, thereby meeting the A standard of the national primary sewage discharge standard;

comparing the quality of untreated directly discharged wastewater with the quality of wastewater discharged after treatment by the domestic wastewater treatment process, it can be found that, as shown in tables 2 and 3, the concentration of pollutants in untreated directly discharged domestic wastewater is high, which causes serious pollution to the environment; after treatment, the content of various pollutants is greatly reduced, the concentration is within the requirements of A standard of national first-level sewage discharge standard, and the pollution to the environment is also greatly reduced.

TABLE 2 comparison of anoxic-aerobic process removal effect when total phosphorus TP is less than or equal to 1.2mg/L

TABLE 3 comparison of the anaerobic-aerobic process removal when total phosphorus TP > 1.2mg/L

The second embodiment: a wastewater treatment process comprises the following treatment steps:

s01: domestic wastewater is collected to the grid channel 101 through a wastewater pipeline, primary filtration is completed, and insoluble impurities such as water fibers and dead leaves are removed;

s02: the domestic wastewater flows through the phosphorus content monitor 211 from the water outlet pipeline of the grid channel 101, and the total phosphorus concentration in the domestic wastewater at the moment is monitored;

s03: when the phosphorus content monitor 211 judges that the total phosphorus TP in the drainage is less than or equal to 2mg/L, an anoxic-aerobic-anoxic-aerobic process is adopted;

s04: when the phosphorus content monitor 211 judges that the total phosphorus TP in the drainage is more than 2mg/L, an anaerobic-aerobic-anoxic-aerobic process is adopted;

s05: a mixed liquor reflux device 205 is arranged between the aerobic reaction tank 202 and the anoxic reaction tank 201, and the reflux proportion of the mixed liquor is 250%;

s06: domestic wastewater flows into a sedimentation tank 204 from the aerobic reaction tank 202, so that sludge in the domestic wastewater is sedimentated to the bottom of the tank;

s07: a sludge reflux device 206 is arranged between the sedimentation tank 204 and the anaerobic reaction tank 203, and the sludge reflux proportion is 50 percent;

s08: domestic wastewater flows into the ozone mixing pipe from the sedimentation tank 204, and organic matters, turbidity and odor in the wastewater are removed through ozonization treatment;

s09: domestic wastewater flows into the biological pond 210 through the ozone mixing pipe, and a small amount of microorganisms are put into the biological pond 210 to remove byproducts generated by ozonization;

s10: domestic wastewater is discharged from the biological pond 210 into the environment.

The above-mentioned embodiments are merely illustrative and not restrictive, and those skilled in the art can make modifications to the embodiments without inventive contribution as required after reading the present specification, but only protected by the patent laws within the scope of the claims.

Claims

1. A domestic wastewater treatment system comprises

The primary treatment system (1), the primary treatment system (1) comprises a grating channel (101);

the secondary treatment system (2), the secondary treatment system (2) comprises a nitrogen and phosphorus removal device, an ozonization device (20) and a biological pond (210) which are communicated with each other;

the method is characterized in that: the nitrogen and phosphorus removal device comprises a phosphorus content monitor (211), an anaerobic reaction tank (203), an anoxic reaction tank (201), an aerobic reaction tank (202) and a sedimentation tank (204), wherein the phosphorus content monitor (211) is arranged at a water inlet of the nitrogen and phosphorus removal device, and water outlets of the anoxic reaction tank (201) and the anaerobic reaction tank (203) are communicated with the aerobic reaction tank (202); a mixed liquor reflux device (205) is arranged between the aerobic reaction tank (202) and the anaerobic reaction tank (203); the water outlet of the aerobic reaction tank (202) is communicated with the sedimentation tank (204), and a sludge reflux device (206) is arranged between the sedimentation tank (204) and the anaerobic reaction tank (203); a preset phosphorus content concentration value is preset in the phosphorus content detector, and when total phosphorus TP in the wastewater is greater than the preset phosphorus content concentration value, the wastewater enters an anaerobic reaction tank (203); otherwise, the wastewater enters an anoxic reaction tank (201).

2. The domestic wastewater treatment system according to claim 1, wherein: the phosphorus content monitor (211) comprises a screen (2111), a photolysis chamber (2112), a microfluidic mixing chamber (2113) and a detection chamber (2114) and a control chamber (2115) in communication with each other; inside the waste water pipeline before photolysis cavity (2112) was located in screen cloth (2111), be equipped with the reductant of slow flow in microfluid mixing chamber (2113), install ultraviolet monochromatic source in detection room (2114).

3. The domestic wastewater treatment system according to claim 1, wherein: the preset value of the phosphorus content concentration of the phosphorus content detector is 2 mg/L.

4. The domestic wastewater treatment system according to claim 1, wherein: the water inlets of the anoxic reaction tank (201) and the anaerobic reaction tank (203) are respectively provided with an electromagnetic valve, and the electromagnetic valves are in electric signal connection with the control chamber (2115).

5. The domestic wastewater treatment system according to claim 1, wherein: the ozonization device (20) comprises an ozone electrolysis device, an ozone pipe (208) and an ozone mixing tank (209), wherein the ozone mixing tank (209) is communicated with the sedimentation tank (204), and the ozone electrolysis device is communicated with the ozone mixing tank (209) through the ozone pipe (208).

6. The domestic wastewater treatment system according to claim 1, wherein: a grating is arranged in the grating channel (101).

7. The domestic wastewater treatment process is characterized by comprising the following steps:

s01: domestic wastewater is collected to the grid channel (101) through a wastewater pipeline to finish primary filtration;

s02: the domestic wastewater flows through a phosphorus content monitor (211) from a water outlet pipeline of the grid channel (101) to monitor the total phosphorus concentration in the domestic wastewater at the moment;

s03: when the phosphorus content monitor (211) judges that the total phosphorus TP in the drainage is less than or equal to 2mg/L, an anoxic-aerobic-anoxic-aerobic process is adopted;

s04: when the phosphorus content monitor (211) judges that the total phosphorus TP in the drainage is more than 2mg/L, an anaerobic-aerobic-anoxic-aerobic process is adopted;

s05: a mixed liquor reflux device (205) is arranged between the aerobic reaction tank (202) and the anoxic reaction tank (201);

s06: domestic wastewater flows into a sedimentation tank (204) from an aerobic reaction tank (202);

s07: a sludge reflux device (206) is arranged between the sedimentation tank (204) and the anaerobic reaction tank (203);

s08: the domestic wastewater flows into the ozone mixing pipe from the sedimentation tank (204);

s09: the domestic wastewater flows into the biological tank (210) through the ozone mixing pipe;

s10: domestic wastewater is discharged from the biological basin (210) into the environment.

8. The domestic wastewater treatment process according to claim 6, wherein: the mixed liquid reflux ratio of the mixed liquid reflux device (205) is 250%.

9. The domestic wastewater treatment process according to claim 6, wherein: the sludge reflux ratio of the sludge reflux device (206) is 50%.

10. The domestic wastewater treatment process according to claim 6, wherein: the phosphorus content monitor (211) comprises a screen (2111), a photolysis chamber (2112), a microfluidic mixing chamber (2113) and a detection chamber (2114) and a control chamber (2115) in communication with each other; the screen (2111) is arranged in a waste water pipeline in front of the photolysis chamber (2112), a slow-flowing reducing agent is arranged in the microfluid mixing chamber (2113), and an ultraviolet monochromatic light source is arranged in the detection chamber (2114); the phosphorus content detector adopts a phosphomolybdic acid colorimetric method to detect the total phosphorus content.