CN111499102A

CN111499102A - Step purification process for complex organic sewage

Info

Publication number: CN111499102A
Application number: CN202010342560.0A
Authority: CN
Inventors: 陈润华; 柴喜林; 查从品; 毛攀; 周传国; 江红波
Original assignee: Jiangxi Wannian Zhongnan Environmental Protection Industry Co Operative Research Institute Co ltd; Central South University of Forestry and Technology; Jiangxi Gaia Environmental Science and Technology Co Ltd
Current assignee: Jiangxi Wannian Zhongnan Environmental Protection Industry Co Operative Research Institute Co ltd; Central South University of Forestry and Technology; Jiangxi Gaia Environmental Science and Technology Co Ltd
Priority date: 2020-04-27
Filing date: 2020-04-27
Publication date: 2020-08-07

Abstract

The invention provides a step purification process for complex organic sewage, belonging to the field of wastewater treatment. The process comprises the steps of pre-removing heavy metals in the sewage, electrically driving to induce sedimentation of sludge micelle particles, carrying out medicament strengthening and adjusting treatment, carrying out anoxic-anaerobic-aerobic step purification and relevant reflux processes. The process has the advantages of effectively improving the agglomeration performance of sludge flocculation particles in the sewage, reducing the microbial poisoning in biochemical regions, preventing suspended particles from blocking a packing layer and the like, thereby realizing the standard discharge of the low biochemical rate multi-impurity complex organic sewage with high efficiency, energy conservation and low cost, and having higher application and popularization values.

Description

Step purification process for complex organic sewage

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to a complex organic sewage gradient purification process.

Background

While the agricultural science and technology and the livestock and poultry breeding industry develop at a high speed, a large amount of organic sewage containing complex pollutant components such as antibiotics, heavy metals, suspended particles and the like is generated. The sewage has a plurality of technical difficulties of high chemical oxygen consumption, low biochemical rate, large turbidity, difficult separation and sedimentation and the like. In recent years, water body pollution events caused by the random discharge and accumulation of antibiotics, heavy metals, high chemical oxygen consumption and refractory organic matters are frequent, and prevention and control of black and odorous water body pollution and remediation of organic polluted soil and fields become key problems in the field of environmental research in China.

The basic principle of organic wastewater treatment is oxidative degradation, that is, organic substances in wastewater are oxidized and degraded into small molecules and finally converted into inorganic substances such as carbon dioxide, water and inorganic salts. The existing mainstream method mainly comprises two major types of biodegradation method and chemical oxidation method, wherein biodegradation utilizes the action of microbial flora such as aerobic microorganisms and anaerobic microorganisms to degrade organic pollutants in water, the technology has the characteristics of low cost, large anaerobic bacteria degradation load, high aerobic bacteria efficiency and the like, but the biodegradation technology requires the technical premises of high biochemical rate of organic matters in wastewater, no biological toxicity of wastewater and the like. The chemical oxidation process is a method for rapidly depriving electrons of organic matters after a strong oxidant is contacted with the organic matters so as to reduce the content of the organic matters in a water body through oxidative degradation, and is a rapid and efficient organic wastewater treatment process. Especially aiming at the technical problems that the flocculation particles are difficult to grow up, the microorganism in a biochemical region is poisoned, the suspended particles block a packing layer, the biochemical effect of the wastewater is poor and the like in the treatment process of organic wastewater with low biochemical rate and complex components containing heavy metal impurities and suspended matters.

Disclosure of Invention

Aiming at the problems, the invention provides the complex organic sewage step purification process which is economical, feasible, stable in process and high in water purification efficiency, so that the agglomeration performance of sludge flocculation particles in sewage is improved, the risks of microbial poisoning and suspended particles blocking a packing layer in a biochemical region are reduced, the treatment stability of a system is improved, and finally the complex organic sewage with low biochemical rate and multiple impurities is discharged up to the standard at low cost.

The technical scheme provided by the invention is as follows:

a step purification process for complex organic sewage is characterized by comprising the following steps: the sewage enters a water purification system from a wastewater inlet, and is purified and discharged after heavy metal pre-removal, electric flocculation agglomeration reaction, flocculation sedimentation, anoxic biochemical reaction, anaerobic phosphorus removal reaction and aeration nitration reaction in sequence.

Particularly, the step of pre-removing the heavy metals is specifically that after the sewage enters an agglomeration reaction tank, the sewage is filtered by an agglomeration tank filler bed layer filled with a multi-group porous carbon-based composite material.

Particularly, the step of the electric flocculation agglomeration reaction is specifically that the sewage from which heavy metals are removed is contacted with an agglomeration tank turntable connected with a first anode terminal, so that the surface of a sludge micelle in the sewage is positively charged; simultaneously, sludge at the bottom of the anoxic biochemical tank is in contact with an anoxic tank turntable connected with a cathode terminal to enable sludge micelles to be negatively charged, and the sludge micelles with negative charges flow back into a return sludge inlet of the anoxic biochemical tank on the side surface of the agglomeration reaction tank through a first return pipeline; sludge at the bottom of the nitrification aeration tank is contacted with an aeration tank rotating disc connected with a second anode terminal to positively charge sludge micelles, and the positively charged sludge micelles flow back to a return sludge inlet of the nitrification aeration tank on the side surface of the agglomeration reaction tank through a second return pipeline; and mixing the positively charged sludge micelles and the negatively charged sludge micelles in an agglomeration reaction tank, destabilizing, flocculating and growing.

Particularly, the process also comprises the step of adding a treatment agent after the electric flocculation agglomeration reaction, wherein the agent is an aqueous solution prepared from one or more of polyacrylamide, polymeric ferric sulfate and polymeric aluminum sulfate for sewage with high colloid content and difficult flocculation and sedimentation, and/or the agent is an aqueous solution prepared from one or more of hydrogen peroxide, sodium hypochlorite and sodium chlorate for sewage with low biochemical rate and high chemical oxygen consumption.

Particularly, the process also comprises the step of refluxing sludge micelles and anaerobic bacteria in the anaerobic biochemical tank to the anaerobic biochemical tank, wherein the step specifically comprises the steps of after sewage subjected to anaerobic biochemical treatment enters the anaerobic dephosphorization tank, passing through an anaerobic tank turntable, allowing the sludge micelles and the anaerobic bacteria in the sewage to pass through a sludge outlet at the bottom of the anaerobic dephosphorization tank, returning to the anaerobic biochemical tank through a third return pipeline, and adjusting the size of the return flow through a one-way valve and/or a return pump so as to adjust the microbial population quantity of the anaerobic and anoxic procedures.

Particularly, the process also comprises a step of jet flow oxygenation between the anaerobic phosphorus removal reaction and the aeration nitrification reaction, wherein the step is that the upper-layer sewage after the anaerobic phosphorus removal reaction flows into the aeration nitrification tank through a second wastewater pump and a jet flow reactor which are connected through a pipeline at the top of the anaerobic phosphorus removal tank, wherein the second wastewater pump arranged at the front end of the jet flow reactor sucks air into water through an oxygen inlet through negative pressure to generate a large amount of micro bubbles so as to quickly improve the dissolved oxygen value in the sewage.

Particularly, the specific steps of the aeration nitrification reaction are that sewage flowing into the aeration nitrification tank passes through the aeration nitrification tank from bottom to top through an aeration tank rotating disc and an aeration tank packing bed layer, wherein aerobic bacteria are propagated on the surface of the aeration tank packing bed layer, and organic matters in the water body are degraded by taking dissolved oxygen and the organic matters in the sewage as self energy sources, so that purified water is obtained.

In particular, anoxic biochemical reaction, anaerobic phosphorus removal reaction and aeration nitration reaction respectively occur in an anoxic tank filler bed layer, an anaerobic tank filler bed layer and an aeration tank filler bed layer, and the filler bed layers are fixed bed layers or flowing bed layers; one or more porous carbon-based composite materials with multiple pores and rich functional groups are filled in the filler bed layer, and preferably, the porous carbon-based composite materials are iron-carbon-based composite materials.

In particular, the porous carbon-based composite material is prepared by adopting fungi hypha composite carbon nano tubes or graphene oxide, performing surface functionalization treatment and then carbonizing at low temperature.

In particular, the process also includes the provision of a grate at the waste water inlet to initially intercept large particulate matter entering the apparatus.

The complex organic sewage step purification process provided by the invention has the following advantages:

1. multi-cycle electrically driven induction enhanced colloid flocculation: PAM and PAC are required to be added in the traditional flocculation sedimentation process and used as floccules to destabilize the colloid, the process destabilizes the colloid by changing the surface electrical property of the micelle, and the stability of the particle micelle is efficiently destroyed and rapidly grown up by inducing crystallization of sludge with positive charges on the surface of an aeration nitrification tank, sludge with negative charges on the surface of an anoxic biochemical tank and the micelle with positive charges in the wastewater under the driving of a flocculation reaction tank rotating disc. The colloid is destabilized by changing the surface electrical property, so that the amount of the external medicament is greatly reduced, the secondary pollution of the external medicament to the water body is reduced, and the energy consumption is reduced.

2. The jet electrode is cooperated with oxygenation to improve degradation efficiency: the traditional aeration oxygenation technology has high energy consumption and low air utilization rate. The process improves the utilization efficiency of oxygen by adopting the synergistic effect of jet flow oxygenation and water electrolysis of the aeration tank turntable. The negative pressure of the front-end pump of the ejector sucks oxygen into water and bubbles generated by water electrolysis have strong chemical reaction activity, a large amount of formed micro bubbles can rapidly improve the dissolved oxygen value in water, the strong chemical activity is obtained, a large amount of micro bubbles are also generated, and the jet aerator is high in efficiency, low in noise and low in energy consumption.

3. Strong impact resistance to heavy metal ions: the traditional biological treatment process is difficult to resist the impact of toxic substances such as heavy metals and the like, and has poor wave resistance. The process comprises a porous carbon-based composite material filler bed layer rich in functional groups, wherein the surface of the porous carbon-based material is rich in a large number of chemical groups such as hydroxyl, carboxyl, amino, sulfydryl and the like, and can form stable matched bonds with heavy metals, so that the heavy metals can be effectively intercepted at the front section of a biochemical treatment process, and the subsequent treatment risk is reduced.

4. The process stability is high: the process designs a multi-backflow pipeline system and a multi-electrode induction and transmission system, wherein the multi-backflow pipeline improves the sedimentation performance of the flocculating particles, so that the sludge of the system is discharged from the only outlet at the bottom of the flocculation sedimentation tank, and meanwhile, the circulation of microorganisms is more stable. The multi-electrode induction and transfer system not only provides colloidal particles with different charges on the surface for flocculation and sedimentation of the system, but also can strengthen a reducing system of anaerobic and anoxic reactions in the cathode region and strengthen an oxidizing system of aerobic reactions in the anode region. In addition, the traditional anaerobic-aerobic process adopts an AAO process, namely anaerobic, anoxic and aerobic. The process adopts anoxic, anaerobic and aerobic processes, and the anaerobic section is arranged at the middle stage, so that the stability of the process is effectively ensured.

5. The biochemical reaction efficiency is high: the process design adopts a porous carbon-based composite material, the carbon nano tube or graphene oxide is compounded by fungal hypha, the carbon nano tube or graphene oxide is prepared, the surface is treated and then the carbon material is carbonized at low temperature, and the carbon material prepared by the process has high surface porosity and is rich in a large number of organic groups such as hydroxyl, carboxyl, amino and the like. Compared with the traditional process, the packed bed adopts the activated carbon and the zeolite as the packing, and the specific surface area is smaller. The process uses porous carbon-based composite material with specific surface area over 200m³The/g can provide more microbial reaction sites, and the biochemical reaction efficiency of the packed bed is enhanced. In particular, the porous carbon-based composite material can be selected from porous iron-carbon-based composite materials, and the iron-carbon-based composite material is formed by combining carboxyl iron, hydroxyl iron, amino iron, sulfydryl iron and zero-valent iron on the surface group of the carbon-based material in a coexisting mannerThe compound can effectively adsorb refractory organic matters at the tail end of organic wastewater treatment, and can also provide inorganic components for the growth activity of microorganisms attached to the compound, so that the water purification efficiency is higher, and the biochemical reaction is more stable; simultaneously has better degradation effect: the main principle of the method is that hydroxyl free radicals can be generated by a micro-battery structure formed between iron and carbon, the generated hydroxyl free radicals have extremely strong oxidation performance, and the method can slowly oxidize, degrade and adsorb organic matters on the surface of a material, so that the water purification effect is further improved.

Drawings

FIG. 1 is a schematic view of a complex organic sewage step purifier.

The names corresponding to the reference numbers in the figures are as follows:

1. an agglomeration reaction tank, 2, a flocculation settling tank, 3, an anoxic biochemical tank, 4, an anaerobic phosphorus removal tank, 5, an aeration nitrification tank, 6, a jet flow reactor, 7, a first anode terminal, 8, an inclined tube plate, 9, a cathode terminal, 10, a second anode terminal, 11, an oxygen inlet, 12, an agglomeration tank rotating disc, 13, an anoxic tank rotating disc, 14, an anaerobic tank rotating disc, 15, an aeration tank rotating disc, 16, an agglomeration tank packing bed, 17, an anoxic tank packing bed, 18, an anaerobic tank packing bed, 19, an aeration tank packing bed, 20, a first wastewater pump, 21, a reagent pump, 22, a fourth check valve, 23, a second wastewater pump, 24, a third check valve, 25, a first reflux pump, 26, a second reflux pump, 27, a sludge pump, 28, a first check valve, 29, a second check valve, 30, a fifth check valve, 31, a wastewater inlet, 32, 33, a purified water discharge port, 34. and a waste residue discharge port 35, a third reflux pump.

FIG. 2 is a flow chart of a complicated organic sewage step water purification process.

Detailed Description

For further understanding of the present invention, preferred embodiments of the present invention will be described in further detail below with reference to examples and comparative examples, but the embodiments of the present invention are not limited thereto.

Example 1

The process is suitable for treating complex organic sewage such as Suspended Solid (SS), ammonia nitrogen organic matters, phosphorus-containing organic matters and the like in the wastewater, can be applied to scenes such as treatment and improvement of black and odorous water, treatment of livestock and poultry breeding wastewater, treatment of domestic sewage, restoration of rural pond water and the like, and has the advantages of effectively improving the agglomeration performance of sludge flocculating particles, reducing microbial poisoning in biochemical regions, preventing suspended particles from blocking packing layers and the like, so that the complex organic wastewater with low biochemical rate and multiple impurities is discharged up to the standard with high efficiency, energy conservation and low cost, and the process is an economical, feasible, stable in performance and high in water purification efficiency.

The invention discloses a complex organic sewage step purification process, which is explained by combining an attached figure 1 and an attached figure 2 as follows:

(1) sewage enters the system: the complex organic sewage enters the water purification system through a wastewater inlet 31 and is pumped into the agglomeration reaction tank 1 through a first wastewater pump 20, wherein a grid is arranged at the wastewater inlet 31 to primarily intercept large particles entering the system.

(2) Pre-removing heavy metals in sewage: after entering the agglomeration reaction tank 1, the sewage is filtered by an agglomeration tank filler bed layer 16 filled with a multi-group porous carbon-based composite material so as to slow down heavy metal poisoning in the circulating operation process of a biochemical system.

(3) And (3) electric flocculation agglomeration reaction: the sewage after heavy metal removal is contacted with the conductive agglomeration tank turntable 12 connected with the first anode terminal 7, so that electrons on the surface of the colloidal sludge particles in the sewage are deprived, and the surface of the colloidal sludge groups in the sewage is positively charged. Meanwhile, sludge at the bottom of the anoxic biochemical tank 3 is contacted with an anoxic tank rotating disc 13 connected with a cathode terminal 9, so that the sludge micelle is negatively charged, and the negatively charged sludge is pumped into a return sludge inlet of the anoxic biochemical tank on the side surface of the agglomeration reaction tank 1 through a first return pipeline provided with a first return pump 25 and a first check valve 28; the bottom of the aeration nitrification tank 5 is contacted with an aeration tank rotating disc 15 connected with a second anode terminal 10 to positively charge sludge micelles, and the positively charged sludge is pumped into a return sludge inlet of the aeration nitrification tank on the side surface of the agglomeration reaction tank 1 through a second return pipeline provided with a second return pump 26 and a second one-way valve 29; the sludge with negative electricity and positive electricity and the sludge with positive electricity in the agglomeration reaction tank 1 are mixed, destabilized and flocculated to grow in the agglomeration reaction tank 1.

(4) Adding a treatment agent: a medicament inlet 32 is arranged below the outlet of the packing bed layer 16 of the agglomeration tank 1, and medicaments are pumped into the tank body through a medicament pump 21. The method is characterized in that whether a treatment agent is added or not is selected according to the quality of sewage, for the sewage with high colloid content and difficult flocculation and sedimentation, the agent can be a flocculant agent, specifically can be an aqueous solution prepared from one or more of polyacrylamide, polymeric ferric sulfate and polymeric aluminum sulfate, and for the sewage with low biochemical rate and high chemical oxygen consumption, the agent can be an oxidant agent, specifically can be an aqueous solution prepared from one or more of hydrogen peroxide, sodium hypochlorite and sodium chlorate.

(5) Flocculation and sedimentation: the bottom of the agglomeration reaction tank 1 is communicated with a flocculation settling tank 2, sludge micelles after flocculation growth in the agglomeration reaction tank 1 enter the flocculation settling tank 2, the micelles further grow through an inclined tube plate 8 of the flocculation settling tank 2 and are subjected to layer sedimentation through extrusion, and settled sludge enters a sludge hopper and then is discharged into waste residues through a waste residue discharge port 34 through a pipeline provided with a sludge pump 27 and a fifth one-way valve 30, so that most of solid suspended matters in the sewage are effectively removed.

(6) And (3) negatively charging and refluxing the sludge micelle: the upper layer sewage through the flocculation settling tank 2 enters the side sewage inlet of the anoxic biochemical tank 3 through the fourth one-way valve 22, and is contacted with the anoxic tank turntable 13 connected with the cathode terminal 9, so that suspended sludge micelles in the sewage are negatively charged, and the sludge is settled and separated and enters the agglomeration reaction tank 1 through the first return pipeline, thereby reducing the risk of pipeline blockage in the anoxic biochemical, anaerobic phosphorus removal and aeration nitration reaction processes.

(7) Anaerobic biochemical reaction: the upper layer sewage passes through the anoxic biochemical tank 3 from bottom to top through the anoxic tank filler bed layer 17 filled with the iron-carbon-based composite material, and is efficiently oxidized and degraded on the surface of the flowing iron-carbon-based composite material.

(8) Sludge micelle and anaerobic bacteria backflow: the sewage after the anaerobic biochemical reaction enters a sewage inlet on the side surface of the anaerobic phosphorus removal tank 4 through an outlet on the top of the anaerobic biochemical tank 3, sludge micelles in the sewage passing through the anaerobic tank turntable 14 pass through a sludge outlet on the bottom of the anaerobic phosphorus removal tank 4 and flow back to the sewage inlet of the anaerobic biochemical tank 3 through a third return pipeline provided with a third one-way valve 24 and a third return pump 35, meanwhile, a part of anaerobic bacteria in the anaerobic phosphorus removal tank 4 flow back and are supplemented into the anaerobic biochemical tank 3 through the third return pipeline, the amount of the return flow is adjusted through the one-way valve and the return pump, and then the microbial population quantity of the anaerobic and anoxic processes is adjusted, so that the biochemical reaction efficiency of the anaerobic and anoxic process sections is balanced, active microbial populations in the system keep high degradation activity, and aeration strains are saved and are prevented from flowing into the nitrification section and being inactivated.

(9) Anaerobic phosphorus removal reaction: the upper layer sewage after the anoxic biochemical reaction passes through the anaerobic phosphorus removal tank 4 from bottom to top through the anaerobic tank filler bed layer 18, a large amount of iron-carbon-based composite materials are also arranged in the oxygen tank filler bed layer 18, the iron-carbon-based composite material fluidized bed provides more reaction sites for chemical reaction, and meanwhile, a low dissolved oxygen state creates favorable conditions for effectively removing phosphorus in the sewage.

(10) Jet flow oxygenation: the upper layer sewage after the anaerobic phosphorus removal reaction flows into the aeration nitrification tank 5 through the second waste water pump 23 and the jet flow reactor 6 which are connected through the pipeline at the top of the anaerobic phosphorus removal tank 4, wherein the second waste water pump 23 arranged at the front end of the jet flow reactor 6 sucks air into water through the oxygen inlet 11 through negative pressure to generate a large amount of micro bubbles, and the dissolved oxygen value in the sewage is rapidly improved.

(11) Positively charging and refluxing the sludge micelle: the sewage after jet flow oxygenation enters the aeration nitrification tank 5, and after the sewage is contacted with the aeration tank rotating disc 15 connected with the second anode terminal 10, the solid suspended matters in the sewage flow back to the agglomeration reaction tank 1 through a sludge outlet at the bottom of the aeration nitrification tank 5 and a second return pipeline provided with a second one-way valve 29 and a second return pump 26.

(12) Aeration nitration reaction: the rest sewage without the sludge micelle passes through the aeration nitrification tank 5 from bottom to top through the aeration tank filler bed layer 19 filled with a large amount of iron-carbon-based composite materials, the process adopts the synergistic effect of jet flow oxygenation and water electrolysis of the aeration tank turntable 15 to improve the utilization efficiency of oxygen, aerobic bacteria are propagated on the surface of the iron-carbon-based composite materials, and dissolved oxygen and organic matters in the sewage are used as self energy sources to degrade organic matters in the water body, so that purified water is obtained. The purified water is discharged out of the system through a purified water outlet 33 at the top of the aeration nitrification tank 5.

The domestic sewage in a certain college area is taken as an example and treated by the process, so that solid suspended matters and nitrogen and phosphorus organic matters in the sewage are purified, the domestic sewage initially intercepts large granular matters entering a system through a water inlet grid, then the large granular matters are removed through an electric auxiliary flocculation and flocculation settling area, the concentration of the solid suspended matters in the sewage after flocculation settling reaches 4-10 mg/L, the removal rate reaches 96.5-98.6%, then the sewage is pumped into a cathode filling area at the bottom of an anoxic biochemical tank to carry out deep solid suspended matters removal, the sewage sequentially passes through an anoxic biochemical tank, an anaerobic phosphorus removal tank and an aeration nitrification tank to carry out nitrogen and phosphorus removal, the temperature of the anoxic-anaerobic-aerobic denitrification and phosphorus removal system is controlled at 20-25 ℃, the Dissolved Oxygen (DO) of the anoxic biochemical tank and the anaerobic phosphorus removal tank is controlled at 0.1-0.5 mg/L, the pH of inlet water is basically maintained at 7.3-7.6, the ratio of the aeration nitrification tank is controlled at 1-2:1, the dissolved oxygen consumption is controlled at 3-4 mg/L, the hydraulic retention time (T) is 10h, the water quality is treated by the aeration tank, the total ammonia nitrogen and the sewage is purified by the aerobic nitrification process, and the total ammonia nitrogen and the sewage is subjected to pass through the aerobic nitrification process, and the total ammonia nitrogen and the total nitrogen and.

TABLE 1 Water quality measurement results before and after Sewage treatment

	Before treatment	After treatment	Removal rate
				Water temperature (. degree.C.)	15-25	/	/
CODcr(mg/L)	200-350(304)	32-54	82.2-89.5％
				Solid suspension (SS, mg/L)	150-360(283)	4-10	96.5-98.6％
Ammonia Nitrogen (NH)₄ ⁺-N，mg/L)	40-50	0.4-1.9	95.2-99.3％
				Total nitrogen (TN, mg/L)	45-60	5.6-9.5	78.9-90.6％
Total phosphorus (TP, mg/L)	4-6	<0.5	87.5-91.7％

According to the data, after the complex organic sewage is treated by the complex organic sewage step purification process, the removal rate of indexes such as chemical oxygen consumption, solid suspended matters, ammonia nitrogen, total phosphorus and the like of the effluent is high, and the quality of the effluent stably reaches the national first-class A standard.

Therefore, the process can pre-remove heavy metals in the complex organic sewage, electrically drive and induce particles to settle to remove most sludge particles, and simultaneously, through medicament strengthening and adjusting treatment, an anoxic-anaerobic-aerobic step purification process and a related backflow process, the process can effectively improve the agglomeration performance of sludge flocculation particles in the sewage, reduce microbial poisoning in biochemical regions, prevent suspended particles from blocking packing layers and other risks, and further realize the standard discharge of the complex organic sewage with low biochemical rate and multiple impurities with high efficiency, energy conservation and low cost, thereby being an economical and feasible water purification process with stable performance and high water purification efficiency.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A step purification process for complex organic sewage is characterized by comprising the following steps: the sewage enters a water purification system from a wastewater inlet, and is purified and discharged after heavy metal pre-removal, electric flocculation agglomeration reaction, flocculation sedimentation, anoxic biochemical reaction, anaerobic phosphorus removal reaction and aeration nitration reaction in sequence.

2. The step purification process of complex organic wastewater according to claim 1, wherein the step of pre-removing heavy metals is carried out by filtering the wastewater after entering the agglomeration reaction tank through an agglomeration tank packed bed filled with a porous carbon-based composite material containing a plurality of groups.

3. The step purification process of complex organic sewage according to claim 1, wherein the step of electrocoagulation-agglomeration reaction is specifically that the sewage from which heavy metals are removed is contacted with an agglomeration tank turntable connected to the first anode terminal to positively charge the surface of the sludge micelle in the sewage; simultaneously, sludge at the bottom of the anoxic biochemical tank is in contact with an anoxic tank turntable connected with a cathode terminal to enable sludge micelles to be negatively charged, and the sludge micelles with negative charges flow back into a return sludge inlet of the anoxic biochemical tank on the side surface of the agglomeration reaction tank through a first return pipeline; sludge at the bottom of the nitrification aeration tank is contacted with an aeration tank rotating disc connected with a second anode terminal to positively charge sludge micelles, and the positively charged sludge micelles flow back to a return sludge inlet of the nitrification aeration tank on the side surface of the agglomeration reaction tank through a second return pipeline; and mixing the positively charged sludge micelles and the negatively charged sludge micelles in an agglomeration reaction tank, destabilizing, flocculating and growing.

4. The process for the step purification of complex organic wastewater according to claim 1, further comprising adding a treatment agent after the electrocoagulation-flocculation reaction, wherein for wastewater with high colloid content and difficult flocculation and sedimentation, the treatment agent is an aqueous solution prepared from one or more of polyacrylamide, polyferric sulfate and polyaluminium sulfate, and/or for wastewater with low biochemical rate and high chemical oxygen consumption, the treatment agent is an aqueous solution prepared from one or more of hydrogen peroxide, sodium hypochlorite and sodium chlorate.

5. The step purification process of complex organic sewage as claimed in claim 3, further comprising the step of returning the sludge micelles and anaerobic bacteria in the anoxic biochemical tank to the anoxic biochemical tank, wherein the step is that after the sewage after the anoxic biochemical treatment enters the anaerobic dephosphorization tank, the sludge micelles and anaerobic bacteria in the sewage pass through a sludge outlet at the bottom of the anaerobic dephosphorization tank and then return to the anoxic biochemical tank through a third return pipeline, and the amount of the return flow is adjusted through a one-way valve and/or a return pump so as to adjust the microbial population quantity of the anoxic and anaerobic processes.

6. The complicated organic sewage step purification process as claimed in claim 1, further comprising a step of jet aeration between the anaerobic dephosphorization reaction and the aeration nitrification reaction, wherein the step of jet aeration is implemented by allowing the upper layer sewage after the anaerobic dephosphorization reaction to flow into the aeration nitrification tank through a second wastewater pump and a jet reactor which are connected with each other through a pipeline at the top of the anaerobic dephosphorization tank, wherein the second wastewater pump arranged at the front end of the jet reactor sucks air into water through an oxygen inlet by negative pressure to generate a large amount of micro bubbles so as to rapidly increase the dissolved oxygen value in the sewage.

7. The complicated organic sewage gradient purification process as claimed in claim 6, wherein the aeration nitrification reaction comprises the specific steps that the sewage flowing into the aeration nitrification tank passes through the aeration nitrification tank from bottom to top through the aeration tank rotating disc and the aeration tank packing bed layer, wherein aerobic bacteria are propagated on the surface of the aeration tank packing bed layer, and dissolved oxygen and organic matters in the sewage are used as self energy sources to degrade organic matters in the water body, so as to obtain the purified water.

8. A complicated organic sewage step purification process as claimed in any one of claims 1 to 7, wherein the anoxic biochemical reaction, the anaerobic dephosphorization reaction and the aeration nitration reaction respectively occur in an anoxic tank filler bed layer, an anaerobic tank filler bed layer and an aeration tank filler bed layer, and the above filler bed layers are fixed bed layers or flowing bed layers; one or more porous carbon-based composite materials with multiple pores and rich functional groups are filled in the filler bed layer, and preferably, the porous carbon-based composite materials are iron-carbon-based composite materials.

9. The stepped purification process for complex organic sewage as claimed in claim 8, wherein the porous carbon-based composite material is prepared by performing surface functionalization treatment on a fungal hypha composite carbon nanotube or graphene oxide and then performing low-temperature carbonization.

10. A complex organic wastewater cascade purification process as claimed in claim 1, wherein the process further comprises providing a grating at the wastewater inlet to primarily intercept large particles entering the apparatus.