Treatment method of coking wastewater

Abstract

The invention provides a treatment method of coking wastewater, and relates to the technical field of biological treatment of environmental engineering wastewater. The treatment method of the coking wastewater provided by the invention comprises the following steps: culturing chlorella and activated sludge to obtain first light particles, domesticating the first light particles by using low-concentration first coking wastewater to obtain second light particles resistant to the coking wastewater, and finally biodegrading the high-concentration second coking wastewater by using the second light particles. The second light particles with regular and stable shapes can be rapidly obtained through domestication culture of the low-concentration first coking wastewater, and the domesticated second light particles have good tolerance to the coking wastewater, have good microorganism retention capacity, have the characteristics of being high in toxicity resistance, stable and capable of degrading complex organic matters, and have good application prospects. The coking wastewater can be efficiently and stably treated for a long time.

Description

Technical Field

[0001] The present application relates to the technical field of biological treatment of environmental engineering wastewater, and in particular to a method for treating coking wastewater. Background Art

[0002] Coking wastewater mainly comes from processes such as coking, coal gas purification, and refining of chemical products. Its water quality varies with the quality of raw coal and the different coking processes. During the coking process, tar distillation and phenol refining distillation processes often separate a large amount of high-concentration organic wastewater with poor biodegradability, which needs to be sent to the tar workshop tubular incinerator for incineration. The water quality of coking wastewater is extremely complex. Generally speaking, pollutants in coking wastewater include organic compounds such as phenols and polycyclic aromatic compounds, as well as inorganic substances such as ammonia nitrogen and nitric nitrogen. Since the discharge of coking wastewater into the environment poses great harm to the ecosystem and human health, exploring effective high-salt coking wastewater degradation technology has become an urgent problem to be solved in industrial water treatment.

[0003] Biological treatment is the preferred treatment method over physicochemical methods due to its economical, efficient, and harmless nature. However, it is generally believed that conventional biological treatment methods are not suitable for coking wastewater. Furthermore, the impact of high-concentration coking wastewater fluctuations can inhibit and toxicize microorganisms. Therefore, conventional microbial treatment systems are unable to effectively degrade organic pollutants such as phenanthrene under high-salinity conditions. Summary of the Invention

[0004] The purpose of this application is to provide a method for treating coking wastewater, aiming to solve the problem that existing biological treatment methods are difficult to adapt to coking wastewater and the impact caused by fluctuations in high-concentration coking wastewater will have an inhibitory and toxic effect on microorganisms.

[0005] To achieve the above objectives, the present application provides a method for treating coking wastewater, comprising:

[0006] Mixing Chlorella and activated sludge and inoculating them into a first sequencing batch reactor for cultivation to obtain first light particles;

[0007] Inoculating the first light particles into a second sequencing batch reactor for acclimation, wherein the influent matrix of the second sequencing batch reactor contains the first coking wastewater, to obtain second light particles resistant to coking wastewater;

[0008] inoculating the second light particles into the second coking wastewater in the third sequencing batch reactor to degrade the second coking wastewater;

[0009] Among them, the pollutant concentrations of the first coking wastewater are COD 500-800 mg / L, ammonia nitrogen 15-30 mg / L, and nitric nitrogen 30-50 mg / L; the pollutant concentrations of the second coking wastewater are COD 1200-3000 mg / L, ammonia nitrogen 40-100 mg / L, and nitric nitrogen 80-200 mg / L.

[0010] In some embodiments, the mixed inoculum dry weight ratio of the Chlorella and the activated sludge is 2.5:1 to 3.5:1.

[0011] In some embodiments, the culture conditions of Chlorella are: 0.8-1.2 ml / L of methanol, 70-80 mg / L of ammonium chloride, 280-300 mg / L of potassium nitrate, 25-30 mg / L of calcium chloride, 40-50 mg / L of magnesium sulfate, and 45-55 mg / L of dipotassium hydrogen phosphate.

[0012] In some embodiments, the inoculation dry weight concentration of the first light particles and the second light particles is 2-4 gSS / L.

[0013] In some embodiments, the first sequencing batch reactor operates according to a plurality of sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal and idle stage;

[0014] The total operation time of the four stages is controlled within 6 hours, the feeding stage is 5 to 10 minutes, the aerobic aeration stage is 5 hours and 10 minutes to 5 hours and 30 minutes, the static stratification stage is 5 to 10 minutes, and the supernatant removal and idle stage is 20 to 30 minutes.

[0015] In some embodiments, the second sequencing batch reactor operates according to a plurality of sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage;

[0016] The total operation time of the four stages is controlled within 12 hours, with a feeding stage of 5 to 10 minutes, an aerobic aeration stage of 11 hours and 30 minutes to 11 hours and 45 minutes, a static stratification stage of 5 to 10 minutes, and a supernatant removal stage of 5 to 10 minutes.

[0017] In some embodiments, the third sequencing batch reactor operates according to a plurality of sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage;

[0018] The total operation time of the four stages is controlled at 12h to 24h, the feeding stage is 5 to 10 minutes, the aerobic aeration stage is 11 hours and 30 minutes to 23 hours and 45 minutes, the static stratification stage is 5 to 10 minutes, and the supernatant removal stage is 5 to 10 minutes.

[0019] In some embodiments, at least one of the following conditions is met:

[0020] A. The culture temperature is controlled at 22-27°C;

[0021] B. The dissolved oxygen in the culture is controlled at 2-4 mg / L;

[0022] C. The light intensity of the culture is controlled at 4000-6000 lx;

[0023] D. The culture time is 4 to 6 weeks.

[0024] In some embodiments, at least one of the following conditions is met:

[0025] A. The dissolved oxygen in the acclimation is controlled at 2-4 mg / L;

[0026] B. The acclimation temperature is controlled at 22-27°C;

[0027] C. the pH of the acclimation is controlled at 6 to 8;

[0028] D. The light intensity of the acclimation is controlled at 4000lx~6000lx;

[0029] E. The acclimation time is 30 to 40 days.

[0030] In some embodiments, at least one of the following conditions is met:

[0031] A. The degradation temperature is controlled at 22-27°C;

[0032] B. The dissolved oxygen during the degradation is controlled at 2-4 mg / L.

[0033] Compared with the prior art, the advantages of this application include:

[0034] The treatment method of coking wastewater provided in the present application includes culturing Chlorella and activated sludge to obtain first light particles, then acclimating the first light particles with low-concentration first coking wastewater to obtain second light particles resistant to coking wastewater, and finally using the second light particles to biodegrade the high-concentration second coking wastewater. The present application can quickly obtain second light particles with regular and stable shapes through acclimation and cultivation of low-concentration first coking wastewater. The acclimated second light particles have good tolerance to coking wastewater and good microbial retention capacity, and have the characteristics of strong toxicity resistance, stability and the ability to degrade complex organic matter, and can treat coking wastewater efficiently and stably for a long time. In the present application, it is only necessary to acclimate the light particles with low-concentration coking wastewater, and then operate them in a sequencing batch reactor for a long time. The operation is simple, the economy is high, and there is a certain prospect for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0036] Figure 1 This is a light microscope image of the second light particle resistant to coking wastewater in Example 1;

[0037] Figure 2 This is a graph showing the results of the second light particles resistant to coking wastewater in Example 1 degrading coking wastewater;

[0038] Figure 3 This is a light microscope image of the second light particle resistant to coking wastewater in Example 2;

[0039] Figure 4 This is a graph showing the results of the second light particles resistant to coking wastewater in Example 2 degrading coking wastewater;

[0040] Figure 5 This is a graph showing the results of the degradation of coking wastewater by the second light particles of Examples 2 and 3 and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0041] As used herein:

[0042] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0043] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0044] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0045] In these examples, parts and percentages are by mass unless otherwise indicated.

[0046] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the mass of all components is not limited to 100 parts.

[0047] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0049] The term "COD" stands for chemical oxygen demand, also known as chemical oxygen consumption (COD). It is an important comprehensive indicator used to indicate the amount of organic matter and reducing substances such as nitrites, ferrous salts, and sulfides in water. COD refers to the amount of oxidant consumed when a strong oxidant is used to oxidize organic matter and some reducing substances in water under certain conditions. It is expressed in mg / L of oxygen. A higher COD value indicates a greater concentration of oxygen-demanding pollutants in the water and a greater degree of contamination.

[0050] The present application provides a method for treating coking wastewater, comprising:

[0051] S100: Chlorella and activated sludge are mixed and inoculated into a first sequencing batch reactor for cultivation to obtain first light particles.

[0052] S200: inoculating the first light particles into a second sequencing batch reactor for acclimation, wherein the influent matrix of the second sequencing batch reactor contains the first coking wastewater, to obtain second light particles resistant to coking wastewater.

[0053] S300: inoculating the second light particles into the second coking wastewater in the third sequencing batch reactor to degrade the second coking wastewater.

[0054] Among them, the pollutant concentrations of the first coking wastewater are COD 500-800 mg / L, ammonia nitrogen 15-30 mg / L, and nitrate nitrogen 30-50 mg / L; the pollutant concentrations of the second coking wastewater are COD 1200-3000 mg / L, ammonia nitrogen 40-100 mg / L, and nitrate nitrogen 80-200 mg / L.

[0055] The method for treating coking wastewater provided in the present application includes culturing Chlorella and activated sludge to obtain first light particles, then acclimating the first light particles with low-concentration first coking wastewater to obtain second light particles resistant to coking wastewater, and finally using the second light particles to biodegrade high-concentration second coking wastewater. The present application can quickly obtain second light particles with regular and stable shapes through acclimation and cultivation of low-concentration first coking wastewater. The acclimated second light particles have good tolerance to coking wastewater and good microbial retention capacity, are highly resistant to toxicity, are stable, and can degrade complex organic matter, and can treat coking wastewater efficiently and stably over a long period of time.

[0056] Among them, light particles are a special bacteria-algae symbiotic system, specifically referring to the co-aeration and mixed cultivation of microalgae and activated sludge to a dense particle structure.

[0057] In some embodiments, the chlorella is pure strain chlorella purchased from the Institute of Hydrobiology, Chinese Academy of Sciences. Because chlorella is easy to culture, grows quickly, has a high protein content, and has strong adhesion, it is easier to quickly culture into stable light particles.

[0058] In some embodiments, the first sequencing batch reactor in step S100 is a long cylindrical reactor with a height of 100 cm and a diameter of 6 cm. This high aspect ratio reactor provides higher hydraulic shear force, a longer circulation path, and a higher sludge collision frequency, making it easier for the microbial flocs to form a regular particle structure.

[0059] In some embodiments, the culture temperature in step S100 is controlled at 22-27°C, and the light intensity is controlled at 4000-6000 lx. This is more conducive to the rapid growth of Chlorella. Chlorella is rich in protein and polysaccharides. The increase in these substances facilitates the precise integration of algae and mud, and more quickly forms regularly shaped particles.

[0060] In some embodiments, the dry weight ratio of the mixed inoculum of the Chlorella and the activated sludge in step S100 is 2.5:1 to 3.5:1, for example, it can be 2.5:1, 3.0:1, 3.5:1 or any value between 2.5:1 and 3.5:1.

[0061] In some embodiments, the culture conditions of the Chlorella vulgaris in step S100 are: 0.8-1.2 ml / L of methanol, 70-80 mg / L of ammonium chloride, 280-300 mg / L of potassium nitrate, 25-30 mg / L of calcium chloride, 40-50 mg / L of magnesium sulfate, and 45-55 mg / L of dipotassium hydrogen phosphate.

[0062] More specifically, for example, the following may be used: 1 ml / L methanol, 75 mg / L ammonium chloride, 290 mg / L potassium nitrate, 28 mg / L calcium chloride, 45 mg / L magnesium sulfate, and 50 mg / L potassium hydrogen phosphate.

[0063] In some embodiments, the dissolved oxygen in the culture in step S100 is controlled at 2-4 mg / L.

[0064] In some embodiments, the culturing time in step S100 is 4 to 6 weeks.

[0065] In some embodiments, the first sequencing batch reactor in step S100 is operated according to a plurality of sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal and idle stage;

[0066] The total operation time of the four stages is controlled within 6 hours, the feeding stage is 5 to 10 minutes, the aerobic aeration stage is 5 hours and 10 minutes to 5 hours and 30 minutes, the static stratification stage is 5 to 10 minutes, and the supernatant removal and idle stage is 20 to 30 minutes.

[0067] More specifically, for example, the feeding stage is 5 minutes, the aerobic aeration stage is 5 hours and 20 minutes, the static stratification stage is 5 minutes, and the supernatant removal and idle stage is 30 minutes.

[0068] The running time of the sequencing batch process is set to 6 hours. The shorter hydraulic retention time can increase the load of the bacteria and algae system, enabling it to form a particle structure faster.

[0069] In some embodiments, the aeration intensity during the aerobic aeration stage should be controlled at 3-5 L / min. Too low aeration will result in too low hydraulic conditions in the reactor, which is not conducive to particle formation, while too high aeration will disperse particles that are not dense enough.

[0070] In some embodiments, the dissolved oxygen in the acclimation in step S200 is controlled at 2-4 mg / L; the acclimation temperature is controlled at 22-27°C; the acclimation pH is controlled at 6-8; the light intensity is controlled at 4000lx-6000lx; the time is 30-40 days, and the second light particles with regular and stable shapes that are resistant to coking wastewater are obtained, which can be used for aerobic degradation of real coking wastewater.

[0071] In some embodiments, the dry weight concentration of the inoculated first light particles in step S200 is 2-4 g SS / L, for example, 2 g SS / L, 3 g SS / L, 4 g SS / L, or any value between 2-4 g SS / L. The specific inoculation amount can be adjusted according to actual needs to meet the inoculation amount required for the final wastewater treatment. The unit "g SS / L" refers to the weight of suspended solids per liter of solution. In other words, the dry weight of suspended solids of the first light particles per liter of solution in the second sequencing batch reactor is 2-4 g.

[0072] In some embodiments, the second sequencing batch reactor in step S200 operates according to multiple sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage;

[0073] The total operation time of the four stages is controlled within 12 hours, with a feeding stage of 5 to 10 minutes, an aerobic aeration stage of 11 hours and 30 minutes to 11 hours and 45 minutes, a static stratification stage of 5 to 10 minutes, and a supernatant removal stage of 5 to 10 minutes.

[0074] More specifically, for example, the duration may be: a feeding stage of 5 minutes, an aerobic aeration stage of 11 hours and 45 minutes, a static stratification stage of 5 minutes, and a supernatant removal stage of 5 minutes.

[0075] The stratification phase lasts for 5 to 10 minutes. It's important to note that the stratification phase should be gradually shortened to eliminate light particles that disintegrate due to their difficulty adapting to the coking wastewater environment while retaining particles with strong tolerance. This improves the settling performance of the particles and significantly enriches the dephenolization bacteria.

[0076] In some embodiments, the second light particles in step S300 are inoculated into the second coking wastewater at a dry weight concentration of 2 to 4 gSS / L to treat high-concentration real coking wastewater. The inoculation concentration of the second light particles can be, for example, 2 gSS / L, 3 gSS / L, 4 gSS / L or any value between 2 and 4 gSS / L. The specific inoculation amount can be adjusted according to actual needs and must meet the inoculation amount required for the final sewage treatment. Among them, the unit gSS / L means the weight of suspended solids per liter of solution, that is, the dry weight of suspended solids of the second light particles per liter of solution in the third sequencing batch reactor is 2 to 4 g.

[0077] In some embodiments, the third sequencing batch reactor in step S300 operates according to multiple sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage;

[0078] The total operation time of the four stages is controlled at 12h to 24h, the feeding stage is 5 to 10 minutes, the aerobic aeration stage is 11 hours and 30 minutes to 23 hours and 45 minutes, the static stratification stage is 5 to 10 minutes, and the supernatant removal stage is 5 to 10 minutes.

[0079] More specifically, for example, the total operating time of the four stages is controlled within 12 hours, with a feeding stage of 5 minutes, an aerobic aeration stage of 11 hours and 45 minutes, a standing and stratification stage of 5 minutes, and a supernatant removal stage of 5 minutes; or the total operating time of the four stages is controlled within 24 hours, with a feeding stage of 5 minutes, an aerobic aeration stage of 23 hours and 45 minutes, a standing and stratification stage of 5 minutes, and a supernatant removal stage of 5 minutes.

[0080] In some embodiments, the degradation temperature in step S300 is controlled at 22-27° C.; and the dissolved oxygen is controlled at 2-4 mg / L.

[0081] In this application, only low-concentration coking wastewater is needed to acclimate the light particles, and then the particles are operated in a sequencing batch reactor for a long time. The operation is simple, the economy is high, and there is a certain prospect for promotion and application.

[0082] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0083] Example 1

[0084] This embodiment provides a method for treating coking wastewater, comprising the following steps:

[0085] (1) Cultivating light particles:

[0086] Excess sludge removed from the secondary sedimentation tank of a sewage treatment plant was mixed with Chlorella vulgaris purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, and inoculated into a sequencing batch reactor (SBR). The dry weight ratio of Chlorella to activated sludge was 3:1. The light granule culture formulation was as follows: 1 ml / L methanol, 75 mg / L ammonium chloride, 290 mg / L potassium nitrate, 28 mg / L calcium chloride, 45 mg / L magnesium sulfate, and 50 mg / L dipotassium hydrogen phosphate. The SBR was operated according to a sequencing batch process, with the culture temperature controlled at 25°C, the pH between 7.2 and 7.8, and the aeration rate at 4 L / min. During the SBR operation, each sequencing batch process includes a feeding stage, an aerobic aeration stage, a static stratification stage, a supernatant removal and an idle stage. The total operation time of the four stages is controlled within 6 hours, including 5 minutes for feeding, 5 hours and 20 minutes for the aerobic aeration incubation stage, 5 minutes for the static stratification stage, and 30 minutes for the supernatant removal and idle stage. After 4 weeks of operation, light particles with regular shape and dense structure are obtained.

[0087] (2) Configure low-concentration coking wastewater:

[0088] The formula of low-concentration coking wastewater is as follows: 200ml of coking wastewater from a sewage treatment plant and 1800ml of distilled water.

[0089] (3) Taming light particles:

[0090] The light particles cultured in (1) were inoculated into the SBR at a dry weight concentration of 3 gSS / L, and the SBR was operated according to the sequencing batch process. The acclimation temperature was controlled at 25°C and the aeration intensity was controlled at 4 L / min. During the operation of the SBR, each sequencing batch process included a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage. The total operation time of the four stages was controlled at 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage. After acclimation for 4 weeks, the particles were stable, and light particles tolerant to coking wastewater were obtained. The optical microscope image is shown in FIG. Figure 1 shown.

[0091] (4) Configuration of coking wastewater:

[0092] The formula of coking wastewater is as follows: 400ml of coking wastewater from a sewage treatment plant and 1600ml of distilled water.

[0093] (5) Tolerance to coking wastewater light particle degradation of coking wastewater:

[0094] The acclimated light particles in (3) were inoculated into the SBR at a dry weight concentration of 2 g SS / L. An aeration stone was set at the bottom of the SBR to fully disperse the air and maintain the aerobic environment of the system. The temperature was controlled at 25 ° C and the DO was controlled at 4 mg / L. During the operation of the SBR, each sequencing batch process stage included the feeding stage, the aerobic aeration stage, the static stratification stage, and the supernatant removal stage. The total operation time of the four stages was controlled within 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage.

[0095] At the same time, in order to compare the treatment efficiency of light particle coking wastewater, activated sludge was also set as a control in this embodiment. In this control group, the activated sludge acclimated according to the operation mode in (3) was directly inoculated into the SBR at a dry weight concentration of 2g SS / L, and the coking wastewater configured in (4) was used as the water inlet mechanism, and the operation was carried out in the above manner.

[0096] Take the SBR effluent every day, use spectrophotometer to measure the COD concentration of coking wastewater effluent, calculate the COD removal rate, the results are as follows: Figure 2 As shown, the results show that the light particles of the present application have a COD removal rate of 67% for coking wastewater. Although not completely degraded, the light particles have a higher efficiency in degrading coking wastewater than the control group activated sludge process (47%).

[0097] Example 2

[0098] This embodiment provides a method for treating coking wastewater, comprising the following steps:

[0099] (1) Cultivating light particles:

[0100] Excess sludge removed from the secondary sedimentation tank of a sewage treatment plant was mixed with Chlorella vulgaris purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, and inoculated into a sequencing batch reactor (SBR). The dry weight ratio of Chlorella to activated sludge was 3:1. The light granule culture formulation was as follows: 1 ml / L methanol, 75 mg / L ammonium chloride, 290 mg / L potassium nitrate, 28 mg / L calcium chloride, 45 mg / L magnesium sulfate, and 50 mg / L dipotassium hydrogen phosphate. The SBR was operated according to a sequencing batch process, with the culture temperature controlled at 25°C, the pH between 7.2 and 7.8, and the aeration rate at 4 L / min. During the SBR operation, each sequencing batch process includes a feeding stage, an aerobic aeration stage, a static stratification stage, a supernatant removal and an idle stage. The total operation time of the four stages is controlled within 6 hours, including 5 minutes for feeding, 5 hours and 20 minutes for the aerobic aeration incubation stage, 5 minutes for the static stratification stage, and 30 minutes for the supernatant removal and idle stage. After 4 weeks of operation, light particles with regular shape and dense structure are obtained.

[0101] (2) Configure low-concentration coking wastewater:

[0102] The formula of low-concentration coking wastewater is as follows: 200ml of coking wastewater from a sewage treatment plant and 1800ml of distilled water.

[0103] (3) Taming light particles:

[0104] The light particles cultured in (1) were inoculated into the SBR at a dry weight concentration of 3 gSS / L, and the SBR was operated according to the sequencing batch process. The acclimation temperature was controlled at 25°C and the DO was controlled at 4 mg / L. During the operation of the SBR, each sequencing batch process included a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage. The total operation time of the four stages was controlled within 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage. After acclimation for 4 weeks, the particles were stable, and light particles tolerant to coking wastewater were obtained. The optical microscope image thereof is shown in FIG. Figure 3 shown.

[0105] (4) Configuration of coking wastewater:

[0106] The formula of coking wastewater is as follows: 1000ml of coking wastewater from a sewage treatment plant, 1000ml of distilled water.

[0107] (5) Tolerance to coking wastewater light particle degradation of coking wastewater:

[0108] The acclimated particles in (3) were inoculated into the SBR at a dry weight concentration of 2 g SS / L. An aeration stone was set at the bottom of the SBR to fully disperse the air and maintain an aerobic environment in the system. The temperature was controlled at 25°C and the DO was controlled at 4 mg / L. During the operation of the SBR, each sequencing batch process included a feeding stage, an aerobic aeration stage, a standing stratification stage, and a supernatant removal stage. The total operation time of the four stages was controlled within 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the standing stratification stage, and 5 minutes for the supernatant removal stage.

[0109] At the same time, in order to compare the treatment efficiency of light particle coking wastewater, activated sludge was also set as a control in this embodiment. In this control group, the activated sludge acclimated according to the operation mode in (3) was directly inoculated into the SBR at a dry weight concentration of 2g SS / L, and the coking wastewater configured in (4) was used as the water inlet mechanism, and the operation was carried out in the above manner.

[0110] Take the SBR effluent every day, use spectrophotometer to measure the COD concentration of coking wastewater effluent, calculate the COD removal rate, the results are as follows: Figure 4As shown in the results, the light particles have a COD removal rate of 57% in coking wastewater. Although not completely degraded, the light particles are more efficient in degrading coking wastewater than the control group activated sludge process (28%).

[0111] Example 3

[0112] This embodiment provides a method for treating coking wastewater, comprising the following steps:

[0113] (1) Cultivating light particles:

[0114] Excess sludge removed from the secondary sedimentation tank of a sewage treatment plant was mixed with Chlorella vulgaris purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, and inoculated into a sequencing batch reactor (SBR). The dry weight ratio of Chlorella to activated sludge was 3:1. The light granule culture formulation was as follows: 1 ml / L methanol, 75 mg / L ammonium chloride, 290 mg / L potassium nitrate, 28 mg / L calcium chloride, 45 mg / L magnesium sulfate, and 50 mg / L dipotassium hydrogen phosphate. The SBR was operated according to a sequencing batch process, with the culture temperature controlled at 25°C, the pH between 7.2 and 7.8, and the aeration rate at 4 L / min. During the SBR operation, each sequencing batch process includes a feeding stage, an aerobic aeration stage, a static stratification stage, a supernatant removal and an idle stage. The total operation time of the four stages is controlled within 6 hours, including 5 minutes for feeding, 5 hours and 20 minutes for the aerobic aeration incubation stage, 5 minutes for the static stratification stage, and 30 minutes for the supernatant removal and idle stage. After 4 weeks of operation, light particles with regular shape and dense structure are obtained.

[0115] (2) Configure low-concentration coking wastewater:

[0116] The formula of low-concentration coking wastewater is as follows: 200ml of coking wastewater from a sewage treatment plant and 1800ml of distilled water.

[0117] (3) Taming light particles:

[0118] The light particles cultured in (1) were inoculated into the SBR at a dry weight concentration of 3 gSS / L. The SBR was operated according to the sequencing batch process, with the acclimation temperature controlled at 25°C and the aeration intensity controlled at 4 L / min. During the SBR operation, each sequencing batch process included a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage. The total operation time of the four stages was controlled within 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage. After acclimation for 4 weeks, the particles were stable, and light particles tolerant to coking wastewater were obtained.

[0119] (4) Configuration of coking wastewater:

[0120] The formula of coking wastewater is as follows: 1000ml of coking wastewater from a sewage treatment plant, 1000ml of distilled water.

[0121] (5) Tolerance to coking wastewater light particle degradation of coking wastewater:

[0122] The acclimated light particles in (3) were inoculated into the SBR at a dry weight concentration of 2 g SS / L. An aeration stone was set at the bottom of the SBR to fully disperse the air and maintain the aerobic environment of the system. The temperature was controlled at 25 ° C and the DO was controlled at 4 mg / L. During the operation of the SBR, each sequencing batch process stage included the feeding stage, the aerobic aeration stage, the static stratification stage, and the supernatant removal stage. The total operation time of the four stages was controlled within 24 hours, including 5 minutes for the feeding stage, 23 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage.

[0123] Take the SBR effluent every day, use the spectrophotometer to measure the COD concentration of the coking wastewater effluent, and calculate the COD removal rate, such as Figure 5 As shown, the results show that the COD removal rate of the light particles in this embodiment for coking wastewater is 59%.

[0124] Comparative Example 1

[0125] This comparative example provides a method for treating coking wastewater, comprising the following steps:

[0126] (1) Cultivating light particles:

[0127] Excess sludge removed from the secondary sedimentation tank of a sewage treatment plant was mixed with Chlorella vulgaris purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, and inoculated into a sequencing batch reactor (SBR). The dry weight ratio of Chlorella to activated sludge was 3:1. The light granule culture formulation was as follows: 1 ml / L methanol, 75 mg / L ammonium chloride, 290 mg / L potassium nitrate, 28 mg / L calcium chloride, 45 mg / L magnesium sulfate, and 50 mg / L dipotassium hydrogen phosphate. The SBR was operated according to a sequencing batch process, with the culture temperature controlled at 25°C, the pH between 7.2 and 7.8, and the aeration rate at 4 L / min. During the SBR operation, each sequencing batch process includes a feeding stage, an aerobic aeration stage, a static stratification stage, a supernatant removal and an idle stage. The total operation time of the four stages is controlled within 6 hours, including 5 minutes for feeding, 5 hours and 20 minutes for the aerobic aeration incubation stage, 5 minutes for the static stratification stage, and 30 minutes for the supernatant removal and idle stage. After 4 weeks of operation, light particles with regular shape and dense structure are obtained.

[0128] (2) Configuration of coking wastewater:

[0129] The formula of coking wastewater is as follows: 1000ml of coking wastewater from a sewage treatment plant, 1000ml of distilled water.

[0130] (3) Photocatalytic degradation of coking wastewater:

[0131] The light particles cultured in (1) were inoculated into the SBR at a dry weight concentration of 2 g SS / L. An aeration stone was set at the bottom of the SBR to fully disperse the air and maintain the aerobic environment of the system. The temperature was controlled at 25 ° C and the DO was controlled at 4 mg / L. During the operation of the SBR, each sequencing batch process stage included the feeding stage, the aerobic aeration stage, the static stratification stage, and the supernatant removal stage. The total operation time of the four stages was controlled within 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage.

[0132] Take the SBR effluent every day, use the spectrophotometer to measure the COD concentration of the coking wastewater effluent, and calculate the COD removal rate, such as Figure 5 As shown, the results show that the COD removal rate of the light particles in this comparative example for coking wastewater is only 35%.

[0133] Comparative Example 2

[0134] This comparative example provides a method for treating coking wastewater, comprising the following steps:

[0135] (1) Cultivating light particles:

[0136] Excess sludge removed from the secondary sedimentation tank of a sewage treatment plant was mixed with Chlorella vulgaris purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, and inoculated into a sequencing batch reactor (SBR). The Chlorella vulgaris to activated sludge ratio was 1:1 by dry weight. The light granule culture formulation was as follows: 1 ml / L methanol, 75 mg / L ammonium chloride, 290 mg / L potassium nitrate, 28 mg / L calcium chloride, 45 mg / L magnesium sulfate, and 50 mg / L dipotassium hydrogen phosphate. The SBR was operated according to a sequencing batch process, with the culture temperature maintained at 25°C, the pH between 7.2 and 7.8, and the aeration rate at 4 L / min. During the SBR operation, each sequencing batch process includes a feeding stage, an aerobic aeration stage, a static stratification stage, a supernatant removal and an idle stage. The total operation time of the four stages is controlled within 6 hours, including 5 minutes for feeding, 5 hours and 20 minutes for the aerobic aeration incubation stage, 5 minutes for the static stratification stage, and 30 minutes for the supernatant removal and idle stage. After 4 weeks of operation, light particles with regular shape and dense structure are obtained.

[0137] (2) Configure low-concentration coking wastewater:

[0138] The formula of low-concentration coking wastewater is as follows: 200ml of coking wastewater from a sewage treatment plant and 1800ml of distilled water.

[0139] (3) Taming light particles:

[0140] The light particles cultured in (1) were inoculated into the SBR at a dry weight concentration of 3 gSS / L. The SBR was operated according to the sequencing batch process, with the acclimation temperature controlled at 25°C and the aeration intensity controlled at 4 L / min. During the SBR operation, each sequencing batch process included a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage. The total operation time of the four stages was controlled within 12 hours, including 5 minutes for the feeding stage, 11 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage. After acclimation for 4 weeks, the particles were stable, and light particles tolerant to coking wastewater were obtained.

[0141] (4) Configuration of coking wastewater:

[0142] The formula of coking wastewater is as follows: 1000ml of coking wastewater from a sewage treatment plant, 1000ml of distilled water.

[0143] (5) Tolerance to coking wastewater light particle degradation of coking wastewater:

[0144] The acclimated light particles in (3) were inoculated into the SBR at a dry weight concentration of 2 g SS / L. An aeration stone was set at the bottom of the SBR to fully disperse the air and maintain the aerobic environment of the system. The temperature was controlled at 25 ° C and the DO was controlled at 4 mg / L. During the operation of the SBR, each sequencing batch process stage included the feeding stage, the aerobic aeration stage, the static stratification stage, and the supernatant removal stage. The total operation time of the four stages was controlled within 24 hours, including 5 minutes for the feeding stage, 23 hours and 45 minutes for the aerobic aeration stage, 5 minutes for the static stratification stage, and 5 minutes for the supernatant removal stage.

[0145] Take the SBR effluent every day, use the spectrophotometer to measure the COD concentration of the coking wastewater effluent, and calculate the COD removal rate, such as Figure 5 As shown, the results show that the COD removal rate of the light particles in this comparative example for coking wastewater is only 45%.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0147] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form distinct embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for treating coking wastewater, characterized in that: include: Mixing Chlorella and activated sludge and inoculating them into a first sequencing batch reactor for cultivation to obtain first light particles; Inoculating the first light particles into a second sequencing batch reactor for acclimation, wherein the influent matrix of the second sequencing batch reactor contains the first coking wastewater, to obtain second light particles resistant to coking wastewater; inoculating the second light particles into the second coking wastewater in the third sequencing batch reactor to degrade the second coking wastewater; Among them, the pollutant concentrations of the first coking wastewater are COD 500-800 mg / L, ammonia nitrogen 15-30 mg / L, and nitric nitrogen 30-50 mg / L; the pollutant concentrations of the second coking wastewater are COD 1200-3000 mg / L, ammonia nitrogen 40-100 mg / L, and nitric nitrogen 80-200 mg / L.

2. The method for treating coking wastewater according to claim 1, wherein The mixed inoculum dry weight ratio of the chlorella and the activated sludge is 2.5:1 to 3.5:

1.

3. The method for treating coking wastewater according to claim 1, wherein: The culture conditions of the chlorella are: 0.8-1.2 ml / L of methanol, 70-80 mg / L of ammonium chloride, 280-300 mg / L of potassium nitrate, 25-30 mg / L of calcium chloride, 40-50 mg / L of magnesium sulfate, and 45-55 mg / L of dipotassium hydrogen phosphate.

4. The method for treating coking wastewater according to claim 1, wherein: The inoculation dry weight concentration of the first light particles and the second light particles is 2 to 4 gSS / L.

5. The method for treating coking wastewater according to claim 1, wherein: The first sequencing batch reactor operates according to a plurality of sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal and idle stage; The total operation time of the four stages is controlled within 6 hours, the feeding stage is 5 to 10 minutes, the aerobic aeration stage is 5 hours and 10 minutes to 5 hours and 30 minutes, the static stratification stage is 5 to 10 minutes, and the supernatant removal and idle stage is 20 to 30 minutes.

6. The method for treating coking wastewater according to claim 1, wherein: The second sequencing batch reactor operates according to a plurality of sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage; The total operation time of the four stages is controlled within 12 hours, with a feeding stage of 5 to 10 minutes, an aerobic aeration stage of 11 hours and 30 minutes to 11 hours and 45 minutes, a static stratification stage of 5 to 10 minutes, and a supernatant removal stage of 5 to 10 minutes.

7. The method for treating coking wastewater according to claim 1, wherein: The third sequencing batch reactor operates according to multiple sequencing batch processes, wherein the sequencing batch processes include: a feeding stage, an aerobic aeration stage, a static stratification stage, and a supernatant removal stage; The total operation time of the four stages is controlled at 12h to 24h, the feeding stage is 5 to 10 minutes, the aerobic aeration stage is 11 hours and 30 minutes to 23 hours and 45 minutes, the static stratification stage is 5 to 10 minutes, and the supernatant removal stage is 5 to 10 minutes.

8. The method for treating coking wastewater according to any one of claims 1 to 7, characterized in that: At least one of the following conditions is met: A. The culture temperature is controlled at 22-27°C; B. The dissolved oxygen in the culture is controlled at 2-4 mg / L; C. The light intensity of the culture is controlled at 4000-6000 lx; D. The culture time is 4 to 6 weeks.

9. The method for treating coking wastewater according to any one of claims 1 to 7, characterized in that: At least one of the following conditions is met: A. The dissolved oxygen in the acclimation is controlled at 2-4 mg / L; B. The acclimation temperature is controlled at 22-27°C; C. the pH of the acclimation is controlled at 6 to 8; D. The light intensity of the acclimation is controlled at 4000lx~6000lx; E. The acclimation time is 30 to 40 days.

10. The method for treating coking wastewater according to any one of claims 1 to 7, characterized in that: At least one of the following conditions is met: A. The degradation temperature is controlled at 22-27°C; B. The dissolved oxygen during the degradation is controlled at 2-4 mg / L.

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