A sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method

Abstract

The application provides a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method and system. The method is characterized by inoculating specific bacteria in an anaerobic reactor, an anoxic reactor and an aerobic reactor which are sequentially connected, and then making the coking wastewater to be treated sequentially pass through the anaerobic reactor, the anoxic reactor and the aerobic reactor, and then precipitating in a sedimentation tank, so as to realize wastewater treatment. In the above process, the coking wastewater to be treated sequentially passes through the anaerobic reactor inoculated with sulfate-reducing bacteria, the anoxic reactor inoculated with sulfur autotrophic denitrifying bacteria and the aerobic reactor inoculated with nitrifying bacteria, and the "sulfur cycle" is embedded in the coking wastewater treatment process, so that various pollutants in the coking wastewater can be effectively removed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coking wastewater treatment, and particularly relates to a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method. BACKGROUND

[0002] As there are many key industrial enterprises in the Yangtze River and Yellow River Basin, the complex industrial wastewater generated by the enterprises is an important source of pollutants in the Yangtze River and Yellow River Basin. As a kind of high-difficult-to-treat industrial wastewater, coking wastewater in the steel industry has been paid special attention in the ecological protection of the Yangtze River and Yellow River Basin. Unlike municipal sewage treatment, coking wastewater is complex in composition and has biological toxicity, and contains poorly biodegradable components such as polycyclic aromatic hydrocarbons (PAHs), phenolic compounds, heterocyclic compounds, thiocyanate, ammonia and cyanide, etc. In addition, the carbon emission in the coking wastewater treatment process is large, and the traditional biological treatment process has an unsatisfactory treatment effect on COD, NH4 + -N and other pollutants in coking wastewater, and the tolerance of functional flora to the toxicity of coking wastewater is low. Therefore, it is necessary to study a high-efficiency biological treatment process for the difficult-to-treat status of coking wastewater, construct a low-carbon stable biological treatment unit, and provide strong scientific and technological support for the safety protection and governance capacity of the Yangtze River, Yellow River and other key river basins.

[0003] The sulfur-mediated process often uses sulfur for electron transfer, and common reactions include sulfate reduction, sulfur autotrophic denitrification and sulfur disproportionation, etc. The sulfur-mediated process has the advantages of low sludge production, no need for external carbon source and low energy consumption. The sulfur-mediated process is currently often used for treating municipal sewage rich in sulfur, such as seawater flushing toilet sewage, etc. However, the sulfur-mediated process is rarely used in coking wastewater. Therefore, it is of great significance to explore suitable working conditions of the sulfur-mediated process in the field of coking wastewater, improve the treatment efficiency of coking wastewater and reduce the cost of wastewater treatment.

[0004] Therefore, it is necessary to design an improved sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method to solve the above problems. SUMMARY

[0005] The present application aims to provide a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method.

[0006] To achieve the above-mentioned purpose, the present application provides a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method, which comprises the following steps:

[0007] Inoculating anaerobic seed sludge in the anaerobic reactor provided with internal reflux, and performing in-situ domestication to enrich sulfate-reducing bacteria;

[0008] Inoculating anoxic seed sludge in the anoxic reactor provided with filler, and performing in-situ domestication to enrich sulfur autotrophic denitrifying bacteria;

[0009] Inoculate aerobic sludge in the aerobic reactor with external reflux and conduct in-situ domestication to enrich nitrifying bacteria;

[0010] The coking wastewater is introduced into the anaerobic reactor, and sequentially passes through the anaerobic reactor, the anoxic reactor and the aerobic reactor, and 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] Further, the influent pH of the anaerobic reactor is 7.8-8.3.

[0012] Further, the influent pH of the anoxic reactor is 7.5-7.8.

[0013] Further, the influent pH of the aerobic reactor is 7.5-8.0.

[0014] Further, the reflux ratio of the anaerobic reactor is 10-15.

[0015] In particular, the above method is performed by means of a wastewater treatment system for treating coking wastewater, which comprises an anaerobic reactor, an anoxic reactor, an aerobic reactor and a sedimentation tank connected in sequence;

[0016] The anaerobic reactor is provided with an internal reflux structure, the aerobic reactor and the sedimentation tank are provided with a first external reflux structure, the first external reflux structure is used for refluxing sludge in the sedimentation tank to the aerobic reactor, and the sedimentation tank and the anoxic reactor are provided with a second external reflux structure, the second external reflux structure is used for refluxing part of liquid in the sedimentation tank to the anoxic reactor.

[0017] The bottom of the anaerobic reactor is provided with a water inlet, the water inlet is connected with a water inlet pump outside; the anoxic reactor and the anaerobic reactor are provided with a first pipeline for connecting the water inlet of the anoxic reactor and the water outlet of the anaerobic reactor; the anoxic reactor and the aerobic reactor are provided with a second pipeline for connecting the water outlet of the anoxic reactor and the water inlet of the aerobic reactor, and the aerobic reactor is further provided with a third pipeline for connecting the water outlet of the aerobic reactor and the water inlet of the sedimentation tank.

[0018] Further, the anaerobic reactor is provided with a three-phase separator, the three-phase separator is arranged at the upper part of the anaerobic reactor, and the anaerobic reactor and the upper space of the three-phase separator together constitute a sludge-water separation zone.

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

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

[0021] Further, the reflux ratio of the internal reflux structure is 10-15, the reflux ratio of the first external reflux structure is 1-2, and the reflux ratio of the second external reflux structure is 2-4.

[0022] Further, the fillers are biochemical cotton.

[0023] The present application has the following beneficial effects:

[0024] The sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method provided by the present application can realize wastewater treatment by inoculating specific bacteria in the anaerobic reactor, the anoxic reactor and the aerobic reactor which are sequentially connected, and then making the coking wastewater to be treated sequentially pass through the anaerobic reactor, the anoxic reactor and the aerobic reactor, and then pass through the sedimentation tank for sedimentation. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure is a structural schematic diagram of the wastewater treatment system involved in the wastewater treatment of the present application.

[0026] Figure 2 The figure is a principle diagram of the wastewater treatment of the present application.

[0027] Figure 3 The figure is a COD change diagram in the wastewater treatment process of Example 2 of the present application.

[0028] Figure 4 The figure is a phenol concentration change diagram in the wastewater treatment process of Example 2 of the present application.

[0029] Figure 5 The figure is a SCN concentration change diagram in the wastewater treatment process of Example 2 of the present application. -

[0030] Figure 6 The figure is a TN concentration change diagram in the wastewater treatment process of Example 2 of the present application.

[0031] Figure 7 ​The figure of TOC concentration change in the wastewater treatment process of embodiment 2 of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be described in detail below with reference to the drawings and specific embodiments.

[0033] Here, it also needs to be explained that, in order to avoid the present application being obscured by unnecessary details, only the structures and / or processing steps closely related to the scheme of the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0034] In addition, it also needs to be explained that the term "comprise", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment.

[0035] The present application provides a sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment method, which comprises the following steps:

[0036] Inoculating anaerobic seed sludge in the anaerobic reactor with internal reflux, and performing in-situ domestication to enrich sulfate-reducing bacteria;

[0037] Inoculating anoxic seed sludge in the anoxic reactor with filler, and performing in-situ domestication to enrich sulfur autotrophic denitrifying bacteria;

[0038] Inoculating aerobic seed sludge in the aerobic reactor with external reflux, and performing in-situ domestication to enrich nitrifying bacteria;

[0039] Passing coking wastewater into the anaerobic reactor, and the wastewater sequentially passes through the anaerobic reactor, the anoxic reactor, the aerobic reactor and the sedimentation tank; the wastewater mainly performs sulfate reduction reaction and thiosulfate reduction reaction in the anaerobic reactor, mainly performs sulfur autotrophic denitrification reaction in the anoxic reactor, and mainly performs nitrification reaction and oxidation reaction in the aerobic reactor; the sludge from the sedimentation tank is refluxed to the aerobic reactor, and part of the supernatant is refluxed to the anoxic reactor. It needs to be explained that the anaerobic seed sludge in the above process is taken from the anaerobic section of a municipal wastewater treatment plant, the anoxic seed sludge is taken from the anoxic section of the municipal wastewater treatment plant, and the aerobic seed sludge is taken from the aerobic section of the municipal wastewater treatment plant.

[0040] In the technical scheme, the coking wastewater to be treated is sequentially passed through the anaerobic reactor, the anoxic reactor and the aerobic reactor inoculated with specific bacteria, so that the specific pollutants in the wastewater are removed step by step through the chemical reaction between the specific pollutants and the specific bacteria in the corresponding reactors, and the effective removal of multiple pollutants in the coking wastewater is realized; the wastewater is treated by selecting sulfur bacteria (sulfate-reducing bacteria and sulfur autotrophic denitrifying bacteria), so that the high resistance to toxicity of the sulfur bacteria is utilized, and the sulfur bacteria can better adapt to the high-toxicity and high-salt water quality environment; in addition, the coking wastewater itself contains a certain amount of sulfate, which can provide an electron acceptor for the sulfate-reducing bacteria, and under the above two factors, the treatment efficiency of the wastewater is effectively improved.

[0041] As an embodiment of the present application, the reflux ratio of the anaerobic reactor is 10-15, which can ensure that the sludge in the anaerobic reactor is effectively mixed with water 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 sludge-water mixture discharged from 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 refluxed to the aerobic reactor, and part of the liquid is refluxed to the anoxic reactor to provide nitrate for the anoxic reactor; by controlling the reflux ratio within the above range, the sludge concentration in the aerobic reactor can be kept constant, and the loss of sludge in the aerobic reactor can be avoided, thereby affecting the biochemical effect.

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

[0043] As an embodiment of the present application, the temperature of the wastewater treatment process is 20-35℃.

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

[0045] Further, the wastewater treatment is realized by means of a wastewater treatment system, and the structure of the wastewater treatment system is as shown in Figure 1As shown, specifically includes the anaerobic reactor, anoxic reactor, aerobic reactor, sedimentation tank, the bottom of the anaerobic reactor is provided with a water inlet, the water inlet is connected with the water inlet pump (not shown in the figure) outside, using the water pump can be treated into the anaerobic reactor coking wastewater, anaerobic reactor is provided with internal reflux structure, reflux ratio is preferably 15, in other embodiments, also can be adjusted according to actual needs; In particular, the anaerobic reactor is also provided with a three-phase separator, the three-phase separator is arranged on the upper part of the anaerobic reactor, the anaerobic reactor and the space above the three-phase separator together constitute the sludge-water separation zone, by setting the three-phase separator, the wastewater can be separated first, to ensure that the anaerobic reactor bacteria population will not be lost. It should be noted that the process of liquid flow and other need to provide power source in this scheme, can be provided by the external power mechanism such as pump power source.

[0046] Specifically, the first pipeline is arranged between the anoxic reactor and the anaerobic reactor, and is used for connecting the water inlet of the anoxic reactor and the water outlet of the anaerobic reactor. The first agitator and the filler are arranged in the anoxic reactor. The first agitator is used for stirring the reaction system in the anoxic reactor, so that the reaction system in the anoxic reactor is in a homogeneous state. In some embodiments, the filler is specifically biochemical cotton, which is arranged in the middle part of the anoxic reactor. The part of the first agitator for stirring is located below the filler. 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 sludge in the anoxic reactor and react under the stirring action of the first agitator in the water treatment process. The seed sludge in the reacted wastewater is blocked by the filler, and the liquid part enters the aerobic reactor. In other embodiments, the first external reflux structure is arranged between the aerobic reactor and the sedimentation tank, and the reflux ratio is 1-2.

[0047] The second pipeline is arranged between the anoxic reactor and the aerobic reactor, and is used for connecting 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 topmost part of the filler. The third pipeline is arranged on the aerobic reactor, and is used for connecting the water outlet of the aerobic reactor and the water inlet of the sedimentation tank. The second agitator is arranged in the aerobic reactor, so that the aerobic reactor is kept in a homogeneous state. The first external reflux structure is arranged between the aerobic reactor and the sedimentation tank, and is used for refluxing the sludge in the sedimentation tank to the aerobic reactor. The reflux ratio is 1-2. The aeration device is further arranged in the aerobic reactor, and is used for maintaining an aerobic environment in the aerobic reactor. 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 the amount of wastewater to be treated. As long as the actual application requirements can be met, this is not limited herein.

[0048] Further, the second external reflux structure is arranged between the sedimentation tank and the anoxic reactor, which is used to reflux part of the liquid in the sedimentation tank to the anoxic reactor, and the reflux ratio is 2-4; and the mud scraper is arranged in the sedimentation tank, so that the sludge precipitated in the sedimentation tank can be scraped off, facilitating the subsequent sludge reflux and sludge discharge.

[0049] The working principle of the wastewater treatment system for treating wastewater is as follows: during the treatment of wastewater, the whole system is in a working state, wastewater is first introduced into the anaerobic reactor by means of an external water inlet pump, and the anaerobic sludge is separated from the wastewater under the separation action of the three-phase separator in the sludge-water separation zone, and the wastewater is mainly subjected to sulfate reduction reaction (chemical reaction formula is 100COD + 150.2SO4 2- +43.7H2O→53.2H2S + 1.9Sludge + 190.9HCO3 - ) and thiosulfate reduction reaction in the anaerobic reactor, in which process, under the driving of 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 the sulfate to sulfide; meanwhile, thiosulfate is subjected to reduction reaction (chemical reaction formula is CH3COO - +S2O3 2- +H2O→2HS - +2HCO3 - +H + ), and the coking wastewater rich in sulfide, sulfate and residual thiosulfate enters the anoxic unit; the wastewater treated in the anaerobic reactor is mainly subjected to 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- , and the chemical reaction formula of thiocyanate autotrophic denitrification is 5SCN - +8NO3 - →5SO42- +5NH4 + +4N2+5HCO3 - +5OH - 3SCN - +8NO2 - +2H₂O+8H + →3SO4 2- +3NH4 + Driven by sulfur-oxidizing bacteria, the sulfides produced in the anaerobic unit, the remaining thiosulfate, and the thiocyanate present in the coking wastewater serve as electron donors, while the nitrate / nitrite in the nitrification liquid returned from the sedimentation tank acts as electron acceptors. This process involves autotrophic denitrification, converting nitrate nitrogen into nitrogen gas and sulfur back into sulfate. The treated wastewater then enters the aerobic reactor. The chemical reaction for the aerobic oxidation of thiocyanate in this process is as follows:

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

[0054] 0.0044C5H7O2N+0.121NH4 + +0.125SO4 2- +0.121HCO3 - +0.1253H + The wastewater treated in the anoxic reactor undergoes nitrification and oxidation in the aerobic reactor, consuming the remaining COD. Driven by nitrifying bacteria, oxygen is 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 abundant in the coking wastewater undergoes a mineralization reaction (chemical reaction formula is...).

[0055] C6H6O + 4.12O2 + 0.504HCO 3- +0.504NH4 + →0.504C5H7O2N+13.356H2O+3.984CO2), the remaining thiocyanate ions are oxidized to nitrates / nitrites (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 settles. 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 application will be further described below in combination with specific examples.

[0057] Example 1

[0058] The present embodiment provides a wastewater treatment system applicable to the sulfur-mediated anaerobic-anoxic-aerobic coking wastewater treatment, which comprises an anaerobic reactor, an anoxic reactor, an aerobic reactor and a sedimentation tank connected in sequence, the anaerobic reactor is used for the sulfate reduction reaction and the thiosulfate reduction reaction of wastewater, the anoxic reactor is used for the sulfur autotrophic denitrification reaction of wastewater treated by the anaerobic reactor, and the aerobic reactor is used for the nitrification reaction and oxidation reaction of wastewater treated by the anoxic reactor.

[0059] Specifically, the bottom of the anaerobic reactor is provided with a water inlet connected with a water inlet pump outside, and the water inlet pump is 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 15; in particular, the anaerobic reactor is further provided with a three-phase separator, which is a triangular funnel in the present embodiment, and is fixed at the upper part of the anaerobic reactor, the funnel neck of the funnel extends to the outside through the top of the anaerobic reactor and is in communication with air, the distance between the edge of the funnel body and the inner side wall of the anaerobic reactor is 10 mm, and the anaerobic reactor and the space above the three-phase separator together constitute a sludge-water separation zone, and by setting the three-phase separator, the wastewater can be first subjected to sludge-water separation to ensure that the bacterial flora in the anaerobic reactor will not be lost.

[0060] Further, the water inlet of the anoxic reactor is connected with the water outlet of the anaerobic reactor through a first pipeline, the anoxic reactor is provided with a first stirrer and biochemical cotton, the first stirrer 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, and the biochemical cotton is filled in the middle part of the anoxic reactor, and the filling amount is two-thirds of the volume of the anoxic reactor.

[0061] The 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, the third pipeline is further 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, the second stirrer is provided in the aerobic reactor, which can ensure that the aerobic reactor is in a homogeneous state; the aerobic reactor is further provided with an aeration device inside, which is used to maintain an aerobic environment in the reactor, and the dissolved oxygen in the aerobic reactor is 3-5 mg / L.

[0062] Further, a first external reflux structure is arranged between the aerobic reactor and the sedimentation tank, and the reflux ratio is 2; a second external reflux structure is arranged between the sedimentation tank and the anoxic reactor, and the reflux ratio is 4; and a mud scraper is arranged in the sedimentation tank.

[0063] Example 2

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

[0065] Inoculate anaerobic seed sludge in the anaerobic reactor with internal reflux, and perform in-situ domestication to enrich sulfate-reducing bacteria;

[0066] Inoculate anoxic seed sludge in the anoxic reactor with filler, and perform in-situ domestication to enrich sulfur autotrophic denitrifying bacteria;

[0067] Inoculate aerobic seed sludge in the aerobic reactor with external reflux, and perform in-situ domestication to enrich nitrifying bacteria;

[0068] Coking wastewater is introduced into the anaerobic reactor, and the wastewater sequentially passes through the anaerobic reactor, the anoxic reactor, the aerobic reactor, and the sedimentation tank. The wastewater mainly performs sulfate reduction and thiosulfate reduction in the anaerobic reactor, mainly performs sulfur autotrophic denitrification in the anoxic reactor, and mainly performs nitrification and oxidation in the aerobic reactor. The sludge from the sedimentation tank is refluxed to the aerobic reactor, and part of the supernatant is refluxed to the anoxic reactor. 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℃.

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

[0070] The above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the present application.

Claims

1. A process for the treatment of coking wastewater by sulphur mediated anaerobic-anoxic-aerobic process, characterized by, The method comprises the following steps: Inoculating anaerobic seed sludge in an anaerobic reactor with internal reflux, and in-situ acclimation to enrich sulfate-reducing bacteria; Inoculating anoxic seed sludge in an anoxic reactor with filler, and in-situ acclimation to enrich sulfur autotrophic denitrifying bacteria; Inoculating aerobic seed sludge in an aerobic reactor with external reflux, and in-situ acclimation to enrich nitrifying bacteria; Passing coking wastewater into the anaerobic reactor, and the coking wastewater sequentially passes through the anaerobic reactor, the anoxic reactor and the aerobic reactor, the coking wastewater undergoes sulfate reduction reaction and thiosulfate reduction reaction in the anaerobic reactor, the coking wastewater undergoes sulfur autotrophic denitrification reaction, thiosulfate autotrophic denitrification reaction and thiocyanate autotrophic denitrification reaction in the anoxic reactor, and the coking wastewater undergoes nitrification reaction and oxidation reaction in the aerobic reactor, the oxidation reaction is aerobic oxidation reaction of thiocyanate and mineralization reaction of phenol.

2. The coking wastewater treatment method according to claim 1, characterized by, The influent pH of the anaerobic reactor is 7.8-8.

3.

3. The coking wastewater treatment method according to claim 1, characterized by, The influent pH of the anoxic reactor is 7.5-7.

8.

4. The coking wastewater treatment method of claim 1, wherein, The influent pH of the aerobic reactor is 7.5-8.

0.

5. The coking wastewater treatment method of claim 1, wherein, The reflux ratio of the anaerobic reactor is 10-15.

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