Sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method

Abstract

The invention provides a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method and system.The method comprises the steps that after specific strains are inoculated into an anaerobic reactor, an anoxic reactor and an aerobic reactor which are sequentially communicated, coking wastewater to be treated sequentially passes through the anaerobic reactor, the anoxic reactor and the aerobic reactor; and settling through a settling pond to realize wastewater treatment. In the process, the coking wastewater to be treated sequentially passes through the anaerobic reactor inoculated with the sulfate reducing bacteria, the anoxic reactor inoculated with the sulfur autotrophic denitrifying bacteria and the aerobic reactor inoculated with the nitrifying bacteria, and sulfur circulation is embedded in the coking wastewater treatment process, so that various pollutants in the coking wastewater are effectively removed.

Description

Technical Field

[0001] The invention relates to the technical field of coking wastewater treatment, in particular to a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method. Background Art

[0002] Since there are many key industrial enterprises in my country in the Yangtze River and Yellow River basins, the complex industrial wastewater they produce is an important source of pollutants in the Yangtze River and Yellow River basins. Coking wastewater generated by the steel industry, as a highly difficult-to-treat industrial wastewater, has received special attention in the ecological protection of the Yangtze River and Yellow River basins. Unlike municipal sewage treatment, coking wastewater has a complex composition and is biologically toxic. It contains difficult-to-degrade components with poor biodegradability, such as polycyclic aromatic hydrocarbons (PAHs), phenolic compounds, heterocyclic compounds, thiocyanates, ammonia and cyanide. In addition, the carbon emissions during the treatment of coking wastewater are relatively large, and traditional biological treatment processes have a low impact on COD and NH4 + The treatment effect of pollutants such as -N is not ideal, and the functional bacteria have a low tolerance to the toxicity of coking wastewater. Therefore, the study of efficient biological treatment processes for the difficult treatment of coking wastewater is carried out, and a low-carbon and stable biological treatment unit is constructed to provide strong scientific and technological support for the safety and governance of key river basins such as the Yangtze River and the Yellow River.

[0003] Sulfur-mediated processes often use sulfur for electron transfer. Common reactions include sulfate reduction, sulfur autotrophic denitrification, sulfur disproportionation, etc., with the advantages of low sludge production, no need for external carbon sources, and low energy consumption. Sulfur-mediated processes are currently commonly used to treat municipal wastewater rich in sulfur, such as seawater toilet flushing wastewater, etc. However, sulfur-mediated processes are rarely used in coking wastewater. Therefore, it is of great significance to explore suitable working conditions for sulfur-mediated processes in the field of coking wastewater, improve the efficiency of coking wastewater treatment, and reduce the cost of wastewater treatment.

[0004] In view of this, it is necessary to design an improved sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method, comprising the following steps:

[0007] Inoculate anaerobic seed sludge in an anaerobic reactor with internal reflow, and perform in-situ acclimatization to enrich sulfate-reducing bacteria;

[0008] Inoculating anoxic seed mud in an anoxic reactor equipped with fillers, and carrying out in-situ acclimatization to enrich sulfur autotrophic denitrifying bacteria;

[0009] Inoculate aerobic seed sludge in an aerobic reactor with external reflow, and perform in-situ acclimatization to enrich nitrifying bacteria;

[0010] The coking wastewater is introduced into the anaerobic reactor, and passes through the anaerobic reactor, the anoxic reactor and the aerobic reactor in sequence. The coking wastewater undergoes sulfate reduction reaction and thiosulfate reduction reaction in the anaerobic reactor, the coking wastewater undergoes sulfur autotrophic denitrification reaction in the anoxic reactor, and the coking wastewater undergoes nitrification reaction and oxidation reaction in the aerobic reactor.

[0011] Furthermore, the pH of the inlet water of the anaerobic reactor is 7.8-8.3.

[0012] Furthermore, the inlet pH of the anoxic reactor is 7.5-7.8.

[0013] Furthermore, the pH of the inlet water of the aerobic reactor is 7.5-8.0.

[0014] Furthermore, the reflow ratio of the anaerobic reactor is 10-15.

[0015] In particular, the method is carried out with the aid of a wastewater treatment system for treating coking wastewater, comprising an anaerobic reactor, an anoxic reactor, an aerobic reactor, and a sedimentation tank connected in sequence;

[0016] An internal reflux structure is provided in the anaerobic reactor, a first external reflux structure is provided between the aerobic reactor and the sedimentation tank, and the first external reflux structure is used to return the sludge in the sedimentation tank to the aerobic reactor; a second external reflux structure is provided between the sedimentation tank and the anoxic reactor, and the second external reflux structure is used to return part of the liquid in the sedimentation tank to the anoxic reactor;

[0017] A water inlet is provided at the bottom of the anaerobic reactor, and the water inlet is connected to an external water inlet pump; a first pipeline is provided between the anoxic reactor and the anaerobic reactor, which is used to connect the water inlet of the anoxic reactor and the water outlet of the anaerobic reactor; a second pipeline is provided between the anoxic reactor and the aerobic reactor, which is used to connect the water outlet of the anoxic reactor and the water inlet of the aerobic reactor; a third pipeline is also provided on the aerobic reactor, and the third pipeline is used to connect the water outlet of the aerobic reactor and the water inlet of the sedimentation tank.

[0018] Furthermore, a three-phase separator is provided in the anaerobic reactor, and the three-phase separator is arranged on the upper part of the anaerobic reactor, and the anaerobic reactor and the upper space of the three-phase separator together constitute a mud-water separation zone;

[0019] The anoxic reactor is provided with a first agitator and a filler, the aerobic reactor is provided with a second agitator, and the sedimentation tank is provided with a mud scraper.

[0020] Furthermore, an aeration device is provided inside the aerobic reactor, and the dissolved oxygen in the aerobic reactor is 3-5 mg / L.

[0021] Furthermore, the reflux ratio of the inner reflux structure is 10-15, the reflux ratio of the first outer reflux structure is 1-2, and the reflux ratio of the second outer reflux structure is 2-4.

[0022] Furthermore, the filler is biochemical cotton.

[0023] The beneficial effects of the present invention are:

[0024] The sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method provided by the present invention can achieve wastewater treatment by inoculating specific bacterial species in sequentially connected anaerobic reactors, anoxic reactors, and aerobic reactors, and then passing the coking wastewater to be treated through the anaerobic reactors, anoxic reactors, and aerobic reactors in sequence, and then precipitating in a sedimentation tank. In the above process, by passing the coking wastewater to be treated through the anaerobic reactor inoculated with sulfate-reducing bacteria, the anoxic reactor inoculated with sulfur autotrophic denitrifying bacteria, and the aerobic reactor of nitrifying bacteria in sequence, the chemical reaction between specific pollutants in the wastewater and specific bacterial species in the corresponding reactors can be utilized to gradually remove the pollutants in the wastewater, thereby achieving effective removal of multiple pollutants in the coking wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a wastewater treatment system involved in wastewater treatment of the present invention;

[0026] Figure 2 It is the principle diagram of wastewater treatment of the present invention;

[0027] Figure 3 This is a graph showing COD changes during wastewater treatment in Example 2 of the present invention;

[0028] Figure 4 This is a graph showing changes in phenol concentration during wastewater treatment in Example 2 of the present invention;

[0029] Figure 5 is the SCN in the wastewater treatment process of Example 2 of the present invention - Concentration variation graph;

[0030] Figure 6 This is a graph showing changes in TN concentration during wastewater treatment in Example 2 of the present invention;

[0031] Figure 7This is a graph showing changes in TOC concentration during wastewater treatment in Example 2 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0034] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0035] The sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method provided by the present invention can remove pollutants in the wastewater by passing the coking wastewater into a wastewater treatment system, and making the wastewater pass through the anaerobic reactor, anoxic reactor, aerobic reactor and sedimentation tank of the wastewater treatment system in sequence. The method specifically comprises the following steps:

[0036] Inoculate anaerobic seed sludge in an anaerobic reactor with internal reflow, and perform in-situ acclimatization to enrich sulfate-reducing bacteria;

[0037] Inoculating anoxic seed mud in an anoxic reactor equipped with fillers, and carrying out in-situ acclimatization to enrich sulfur autotrophic denitrifying bacteria;

[0038] Inoculate aerobic seed sludge in an aerobic reactor with external reflow, and perform in-situ acclimatization to enrich nitrifying bacteria;

[0039] The coking wastewater is passed into the anaerobic reactor, and the wastewater passes through the anaerobic reactor, the anoxic reactor, the aerobic reactor, and the sedimentation tank in sequence. The wastewater mainly undergoes sulfate reduction reaction and thiosulfate reduction reaction in the anaerobic reactor, mainly undergoes sulfur autotrophic denitrification reaction in the anoxic reactor, and mainly undergoes nitrification reaction and oxidation reaction in the aerobic reactor; the sludge coming out of the sedimentation tank is returned to the aerobic reactor, and part of the supernatant is returned to the anoxic reactor. It should be noted that the anaerobic seed sludge in the above process is taken from the anaerobic section of the municipal sewage treatment plant, the anoxic seed sludge is taken from the anoxic section of the municipal sewage treatment plant, and the aerobic seed sludge is taken from the aerobic section of the municipal sewage treatment plant.

[0040] In the above technical scheme, by making the coking wastewater to be treated pass through an anaerobic reactor, an anoxic reactor, and an aerobic reactor inoculated with specific bacterial species in sequence, the chemical reaction between specific pollutants in the wastewater and specific bacterial species in the corresponding reactors can be utilized to gradually remove the pollutants in the wastewater, thereby achieving effective removal of multiple pollutants in the coking wastewater; by selecting sulfur bacteria (sulfate-reducing bacteria and sulfur-autotrophic denitrifying bacteria) to treat the wastewater, their high resistance to toxicity can be utilized to better adapt to the highly toxic and high-salt water quality environment. In addition, the coking wastewater itself contains a certain amount of sulfate, which can provide electron acceptors for sulfate-reducing bacteria. Under the above two factors, the wastewater treatment efficiency is effectively improved.

[0041] As an embodiment of the present invention, the reflux ratio of the anaerobic reactor is 10-15. Through this setting, it can be ensured that the sludge and water inside the anaerobic reactor are effectively mixed during the water treatment process, and the liquid can be in an upward state; the reflux ratio of the sludge in the sedimentation tank to the aerobic reactor is 1-2, and the reflux ratio of part of the liquid in the sedimentation tank to the anoxic reactor is 2-4. The sedimentation tank separates the mud and water mixture flowing out of the aerobic reactor, and the sludge is precipitated in the lower part and the supernatant is in the upper part. The sludge in the lower part of the sedimentation tank is returned to the aerobic reactor, and part of the liquid is returned to the anoxic reactor to provide nitrate for the anoxic reactor. By controlling the reflux ratio within the above range, the sludge concentration inside the aerobic reactor can be kept constant, and the sludge loss of the aerobic reactor can be avoided, which affects the biochemical effect.

[0042] As an embodiment of the present invention, the inlet pH of the anaerobic reactor is 7.8-8.3, the inlet pH of the anoxic reactor is 7.5-7.8, and the inlet pH of the aerobic reactor is 7.5-8.0.

[0043] As an embodiment of the present invention, the temperature of the wastewater treatment process is 20-35°C.

[0044] As an embodiment of the present invention, the residence time of wastewater in the anaerobic reactor is 18-24 hours, the residence time in the anoxic reactor is 18-24 hours, and the residence time in the aerobic reactor is 54-72 hours.

[0045] Furthermore, wastewater treatment is achieved by means of a wastewater treatment system, the structure of which is as follows Figure 1As shown, it specifically includes an anaerobic reactor, an anoxic reactor, an aerobic reactor, and a sedimentation tank that are connected in sequence. A water inlet is provided at the bottom of the anaerobic reactor, and the water inlet is connected to an external water inlet pump (not shown in the figure). The water inlet pump can be used to pass the coking wastewater to be treated into the anaerobic reactor. The anaerobic reactor is provided with an internal reflux structure, and the reflux ratio is preferably 15. In other embodiments, it can also be adjusted according to actual needs; in particular, a three-phase separator is also provided in the anaerobic reactor, and the three-phase separator is arranged on the upper part of the anaerobic reactor. The upper space of the anaerobic reactor and the three-phase separator together constitute a mud-water separation zone. By setting up a three-phase separator, the wastewater can be separated from the mud and water first to ensure that the bacterial flora in the anaerobic reactor will not be lost. It should be noted that the processes involving liquid flow and other processes that require a power source in this scheme can all be provided with a power source through external power mechanisms such as pumps.

[0046] Specifically, a first pipeline is provided between the anoxic reactor and the anaerobic reactor, which is used to connect the water inlet of the anoxic reactor and the water outlet of the anaerobic reactor. A first agitator and a filler are provided in the anoxic reactor. The first agitator is used to stir the reaction system in the anoxic reactor to ensure that the reactor is in a homogeneous state. In some embodiments, the filler is specifically biochemical cotton, which is arranged in the middle of the anoxic reactor. The part of the first agitator that plays a stirring role is located below the filler, and the filling amount is usually two-thirds of the volume of the anoxic reactor. Through the above arrangement, the wastewater to be treated can be contacted with the anoxic seed mud in the anoxic reactor by means of the stirring action of the first agitator during the water treatment process, and react. The seed mud in the wastewater after the reaction is blocked by the filler, and the liquid part enters the aerobic reactor. In other embodiments, a first external reflux structure is provided between the aerobic reactor and the sedimentation tank, and the reflux ratio is 1-2.

[0047] A second pipe is provided between the anoxic reactor and the aerobic reactor, which is used to connect the water outlet of the anoxic reactor and the water inlet of the aerobic reactor. The water outlet of the anoxic reactor is located above the plane where the top of the filler is located. A third pipe is provided on the aerobic reactor, which is used to connect the water outlet of the aerobic reactor and the water inlet of the sedimentation tank. A second agitator is provided in the aerobic reactor, and the second agitator can ensure that the aerobic reactor is kept in a homogeneous state; a first external reflux structure is provided between the aerobic reactor and the sedimentation tank, which is used to return the sludge in the sedimentation tank to the aerobic reactor, and the reflux ratio is 1-2; an aeration device is also provided inside the aerobic reactor, which is used to maintain an aerobic environment in the reactor, and the dissolved oxygen in the anoxic reactor is 3-5 mg / L. It should be noted that the stirring speed of the first agitator and the second agitator can be adjusted according to actual needs, such as selecting according to the amount of wastewater to be treated, as long as it can meet the needs of actual application, and this is not limited here.

[0048] Furthermore, a second external reflux structure is provided between the sedimentation tank and the anoxic reactor, which is used to allow part of the liquid in the sedimentation tank to flow back to the anoxic reactor, with a reflux ratio of 2-4; a scraper is also provided in the sedimentation tank, and the setting of this structure can scrape off the sludge settled in the sedimentation tank, thereby facilitating subsequent sludge return and discharge.

[0049] The working principle of using the above wastewater treatment system to treat wastewater is as follows: During the wastewater treatment process, the entire system is in working condition. First, the wastewater is introduced into the anaerobic reactor with the help of an external water inlet pump. The wastewater enters the mud-water separation zone. Under the separation action of the three-phase separator, the anaerobic seed mud is separated from the wastewater. In the anaerobic reactor, the wastewater mainly undergoes sulfate reduction reaction (the chemical reaction formula is 100COD+150.2SO4 2- +43.7H2O→53.2H2S+1.9Sludge+190.9HCO3 - ) and thiosulfate reduction reaction. In this process, driven by sulfate-reducing bacteria, the available organic carbon source in the coking wastewater is used as an electron donor and sulfate is used as an electron acceptor to reduce sulfate to sulfide. At the same time, thiosulfate is reduced (the chemical reaction formula is CH3COO - +S2O3 2- +H2O→2HS - +2HCO3 - +H + ), generating sulfide and sulfate, the coking wastewater rich in sulfide, sulfate and residual thiosulfate enters the anoxic unit; the wastewater treated by the anaerobic reactor mainly undergoes sulfur autotrophic denitrification reaction in the anoxic reactor (chemical reaction formula is 10NO3 - +0.6HCO3 - +3.6H2S→

[0050] 2.3N2+10.1SO4 2- +0.2Sludge, the chemical reaction formula of thiosulfate autotrophic denitrification is:

[0051] S2O3 2- +1.16NO3 - +0.035CO2+0.519HCO3 - +0.11NH4 + +0.124H2O→

[0052] 0.110C5H7O2N+0.578N2+0.435H + +2SO4 2- The chemical reaction formula of thiocyanate autotrophic denitrification is 5SCN - +8NO3 - →5SO42- +5NH4 + +4N2+5HCO3 - +5OH - ,3SCN - +8NO2 - +2H2O+8H + →3SO4 2- +3NH4 + +4N2+3CO2), driven by sulfur oxidizing bacteria, the sulfide produced by the anaerobic unit, the remaining thiosulfate and the thiocyanate contained in the coking wastewater are used as electron donors, and the nitrate / nitrite in the nitrification liquid returned from the sedimentation tank is used as an electron acceptor to carry out autotrophic denitrification reaction, denitrifying nitrate nitrogen into nitrogen gas, and sulfur is converted back into sulfate. The treated wastewater enters the aerobic reactor. In this process, the chemical reaction formula of aerobic oxidation of thiocyanate is:

[0053] 0.125SCN - +0.017CO2+0.379H2O+0.0228O2→

[0054] 0.0044C5H7O2N+0.121NH4 + +0.125SO4 2- +0.121HCO3 - +0.1253H + The wastewater treated by the anoxic reactor mainly undergoes nitrification and oxidation reactions in the aerobic reactor, and consumes the remaining COD. Driven by nitrifying bacteria, oxygen can be used as an electron donor and ammonia nitrogen as an electron acceptor to oxidize ammonia nitrogen into nitrate / nitrite. Under the action of oxidizing bacteria, the phenol rich in coking wastewater undergoes mineralization reaction (chemical reaction formula is

[0055] C6H6O+4.12O2+0.504HCO 3- +0.504NH4 + →0.504C5H7O2N+13.356H2O+3.984CO2), the remaining thiocyanate is oxidized to nitrate / nitrite (the specific chemical reaction formula is 2NH4 + +2O2 ammonia oxidizing bacteria → 2NO2 - +2H2O+H + ;2NO2 - +O2 nitrite oxidizing bacteria → 2NO3 - ), the treated wastewater enters the sedimentation tank, where it is allowed to settle. After sedimentation, the sludge at the bottom returns to the aerobic reactor through the second external reflux structure, and the supernatant is discharged.

[0056] The sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method provided by the present invention is further described below in conjunction with specific embodiments:

[0057] Example 1

[0058] The present embodiment provides a wastewater treatment system that can be applied to sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment, comprising an anaerobic reactor, an anoxic reactor, an aerobic reactor, and a sedimentation tank that are connected in sequence. The anaerobic reactor is used to supply wastewater for sulfate reduction reaction and thiosulfate reduction reaction to undergo therein, the anoxic reactor is used to supply wastewater treated by the anaerobic reactor for sulfur autotrophic denitrification reaction to undergo therein, and the aerobic reactor is used to supply wastewater treated by the anoxic reactor for nitrification reaction and oxidation reaction to undergo therein.

[0059] Specifically, a water inlet is provided at the bottom of the anaerobic reactor, and the water inlet is connected to an external water inlet pump. The water inlet pump can be used to pass the coking wastewater to be treated into the anaerobic reactor. An internal reflux structure is provided in the anaerobic reactor, and the reflux ratio is 15; in particular, a three-phase separator is also provided in the anaerobic reactor. In this embodiment, the three-phase separator is a triangular funnel, which is fixed on the upper part of the anaerobic reactor. The funnel neck of the funnel passes through the top of the anaerobic reactor and extends to the outside to communicate with the air. The distance between the edge of the funnel body and the inner wall of the anaerobic reactor is 10 mm. The space above the anaerobic reactor and the three-phase separator together constitute a mud-water separation zone. By setting the three-phase separator, the wastewater can be separated from the mud and water first to ensure that the bacterial flora in the anaerobic reactor will not be lost.

[0060] Furthermore, the water inlet of the anoxic reactor is connected to the water outlet of the anaerobic reactor through a first pipe. A first agitator and biochemical cotton are provided in the anoxic reactor. The first agitator is used to stir the reaction system in the anoxic reactor to ensure that the reactor is in a homogeneous state; the biochemical cotton is mainly used to filter and enrich the bacterial flora to reduce the accumulation of harmful substances in the anoxic reactor, thereby improving the water treatment efficiency. The biochemical cotton is filled in the middle of the anoxic reactor, and its filling amount is two-thirds of the volume of the anoxic reactor.

[0061] Among them, a second pipe is provided between the anoxic reactor and the aerobic reactor, which is used to connect the water outlet of the anoxic reactor and the water inlet of the aerobic reactor. A third pipe is also provided on the aerobic reactor, and the third pipe is used to connect the water outlet of the aerobic reactor and the water inlet of the sedimentation tank. A second agitator is provided in the aerobic reactor, and the second agitator can ensure that the aerobic reactor is kept in a homogeneous state; an aerobic reactor is also provided with an aeration device inside, which is used to maintain an aerobic environment in the reactor. The dissolved oxygen in the aerobic reactor is 3-5 mg / L.

[0062] Furthermore, a first external reflux structure is provided between the aerobic reactor and the sedimentation tank, with a reflux ratio of 2; a second external reflux structure is provided between the sedimentation tank and the anoxic reactor, with a reflux ratio of 4, and a sludge scraper is provided in the sedimentation tank.

[0063] Example 2

[0064] In this embodiment, the wastewater treatment system provided in Example 1 is used to treat coking wastewater, wherein the wastewater inlet flow rate is 2.36 mL / min, and the carbon volume load of the entire treatment process is 0.149 kg / m 3 / d, nitrogen volume load is 0.044kg / m 3 / d, the specific processing method includes the following steps:

[0065] Inoculate anaerobic seed sludge in an anaerobic reactor with internal reflow, and perform in-situ acclimatization to enrich sulfate-reducing bacteria;

[0066] Inoculating anoxic seed mud in an anoxic reactor equipped with fillers, and carrying out in-situ acclimatization to enrich sulfur autotrophic denitrifying bacteria;

[0067] Inoculate aerobic seed sludge in an aerobic reactor with external reflow, and perform in-situ acclimatization to enrich nitrifying bacteria;

[0068] The coking wastewater is passed into the anaerobic reactor, and the wastewater passes through the anaerobic reactor, the anoxic reactor, the aerobic reactor, and the sedimentation tank in turn. The wastewater mainly undergoes sulfate reduction and thiosulfate reduction reactions in the anaerobic reactor, sulfur autotrophic denitrification in the anoxic reactor, and nitrification and oxidation reactions in the aerobic reactor; the sludge from the sedimentation tank is returned to the aerobic reactor, and part of the supernatant is returned to the anoxic reactor. Among them, the reflux ratio of the anaerobic reactor is 15, the reflux ratio of the aerobic reactor is 4, the reflux ratio of the sludge in the sedimentation tank is 2, and the dissolved oxygen in the anoxic reactor is 5 mg / L; the influent pH of the anaerobic reactor is 8.0, the influent pH of the anoxic reactor is 7.5, and the influent pH of the aerobic reactor is 7.5; the temperature of the wastewater treatment process is 30°C.

[0069] The results of using the above method to treat coking wastewater are as follows: Figures 3 to 7As shown, specifically: the average COD of the influent in stage one is 1480.62mg / L, the average COD of the influent in stage one is 2681.03mg / L, the average COD of the influent in stage three is 3918.97mg / L, and the average COD removal rates of stages one to three are 82.21%, 81.46% and 83.48% respectively; the average TOC of the influent in stage one is 322.81mg / L, the average TOC of the influent in stage two is 479.14mg / L, the average TOC of the influent in stage three is 747.49mg / L, and the average TOC removal rates of stages one to three are 93.52%, 92.34% and 93.31% respectively; the average TN of the influent in stage one is 65.27mg / L, the average TN of the influent in stage two is 124.68mg / L, and the average TN of the influent in stage three is The average TN value is 250.12 mg / L, and the average TN removal rates of stages one to three are 78.87%, 71.34% and 78.68% respectively; the average volatile phenol content of the influent of stage one is 87.66 mg / L, the average volatile phenol content of the influent of stage two is 170.98 mg / L, and the average volatile phenol content of the influent of stage three is 370.97 mg / L, with a removal rate of 99.76%, and the average removal rates of volatile phenols from stages one to three are 99.61%, 99.68% and 99.75% respectively; the average thiocyanate content of the influent of stage one is 179.55 mg / L, the average thiocyanate content of the influent of stage two is 412.54 mg / L, and the average thiocyanate content of the influent of stage three is 525.74 mg / L, and the average removal rates of thiocyanate from stages one to three are 98.25%, 99.14% and 99.13% respectively. It should be noted that stages one to three here represent the reaction processes of wastewater in the anaerobic reactor, the anoxic reactor, and the aerobic reactor, respectively.

[0070] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method, characterized in that: The steps include: Inoculate anaerobic seed sludge in an anaerobic reactor with internal reflow, and perform in-situ acclimatization to enrich sulfate-reducing bacteria; Inoculating anoxic seed mud in an anoxic reactor equipped with fillers, and carrying out in-situ acclimatization to enrich sulfur autotrophic denitrifying bacteria; Inoculate aerobic seed sludge in an aerobic reactor with external reflow, and perform in-situ acclimatization to enrich nitrifying bacteria; The coking wastewater is introduced into the anaerobic reactor, and passes through the anaerobic reactor, the anoxic reactor and the aerobic reactor in sequence. The coking wastewater undergoes sulfate reduction reaction and thiosulfate reduction reaction in the anaerobic reactor, the coking wastewater undergoes sulfur autotrophic denitrification reaction in the anoxic reactor, and the coking wastewater undergoes nitrification reaction and oxidation reaction in the aerobic reactor.

2. The method for treating coking wastewater according to claim 1, characterized in that: The inlet pH of the anaerobic reactor is 7.8-8.

3.

3. The method for treating coking wastewater according to claim 1, characterized in that: The inlet pH of the anoxic reactor is 7.5-7.

8.

4. The method for treating coking wastewater according to claim 1, characterized in that: The pH of the inlet water of the aerobic reactor is 7.5-8.

0.

5. The method for treating coking wastewater according to claim 1, characterized in that: The reflux ratio of the anaerobic reactor is 10-15.

6. A sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment system, characterized in that: It includes an anaerobic reactor, an anoxic reactor, an aerobic reactor, and a sedimentation tank which are connected in sequence; The anaerobic reactor is provided with an internal reflow structure, and a first external reflow structure is provided between the aerobic reactor and the sedimentation tank, wherein the first external reflow structure is used to return the sludge in the sedimentation tank to the aerobic reactor; A second external reflux structure is provided between the sedimentation tank and the anoxic reactor, and the second external reflux structure is used to return part of the liquid in the sedimentation tank to the anoxic reactor; A water inlet is provided at the bottom of the anaerobic reactor, and the water inlet is connected to an external water inlet pump; a first pipeline is provided between the anoxic reactor and the anaerobic reactor, which is used to connect the water inlet of the anoxic reactor and the water outlet of the anaerobic reactor; a second pipeline is provided between the anoxic reactor and the aerobic reactor, which is used to connect the water outlet of the anoxic reactor and the water inlet of the aerobic reactor; a third pipeline is also provided on the aerobic reactor, and the third pipeline is used to connect the water outlet of the aerobic reactor and the water inlet of the sedimentation tank.

7. The wastewater treatment system according to claim 6, characterized in that: The anaerobic reactor is provided with a three-phase separator, which is arranged on the upper part of the anaerobic reactor. The anaerobic reactor and the upper space of the three-phase separator together constitute a mud-water separation zone; The anoxic reactor is provided with a first agitator and a filler, the aerobic reactor is provided with a second agitator, and the sedimentation tank is provided with a sludge scraper.

8. The wastewater treatment system according to claim 6, characterized in that: An aeration device is also provided inside the aerobic reactor, and the dissolved oxygen in the aerobic reactor is 3-5 mg / L.

9. The wastewater treatment system according to claim 6, characterized in that: The reflux ratio of the inner reflux structure is 10-15, the reflux ratio of the first outer reflux structure is 1-2, and the reflux ratio of the second outer reflux structure is 2-4.

10. The wastewater treatment system according to claim 7, characterized in that: The filler is biochemical cotton.

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