Method for treating phenolic wastewater by using two-stage serial sequencing batch reactor

Abstract

A method for treating phenolic wastewater by two-stage series sequencing batch reactors belongs to the technical field of wastewater treatment, and the specific scheme comprises the following steps: step 1, inoculating domesticated activated sludge into a sequencing batch reactor I and a sequencing batch reactor II; 2, introducing the phenol-containing wastewater into a sequencing batch reactor I, sequentially carrying out anoxic treatment and aerobic treatment, after the aerobic treatment is finished, standing and precipitating to separate mud from water, and discharging supernate; and 3, introducing the supernatant discharged by the sequencing batch reactor I into a sequencing batch reactor II, sequentially carrying out anoxic treatment and aerobic treatment, after the aerobic treatment is finished, standing and precipitating to separate mud and water, and discharging the supernatant to complete the whole process treatment. The method is applied to phenol-containing wastewater treatment, COD and total phenols can be removed by 95% or above after secondary complete treatment, and biotoxicity can be reduced by 98% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and specifically relates to a method for treating phenol-containing wastewater by using a double-stage series sequencing batch reactor (TSBR). Background Art

[0002] Coking wastewater has the characteristics of high organic matter, high NH3-N, and high toxicity. Improper treatment will cause great harm to the environment and human body. The pollutants in coking wastewater are mainly phenolic compounds, and also contain nitrogen heterocyclic compounds (NHCs), polycyclic aromatic hydrocarbons (PAHs), long-chain alkane compounds, NH3-N, cyanide and other substances. Its complex material composition makes coking wastewater have the characteristics of low biodegradability and high biological toxicity, so the difficulty of treatment is much higher than that of urban domestic sewage.

[0003] Biological treatment can effectively remove most pollutants in coking wastewater at a low cost, and has become the core process for removing the main pollutants in coking wastewater. However, the existing treatment processes have their own limitations. For example, anaerobic treatment has a high volumetric load, can withstand wastewater with high organic matter and high toxicity, has low power efficiency, but has a low metabolic rate, is difficult to start, and has low treatment efficiency; aerobic treatment has a higher efficiency in removing organic matter from wastewater, and can quickly decompose and mineralize most small molecules, but microorganisms reproduce and metabolize quickly, produce a high amount of residual sludge, are sensitive to toxic organic matter, can withstand a low load, and have unstable treatment effects. Therefore, it is urgent to develop a new method that can be applied in practice to efficiently and stably treat coking wastewater. This invention can provide a new process method for efficiently and stably treating coking wastewater. Summary of the invention

[0004] In order to efficiently and stably remove the main pollutants such as total phenols and NH3-N in phenol-containing wastewater, the present invention constructs a two-stage sequencing batch reactor (TSBR) in series that operates in anoxic-aerobic mode in time for the treatment of phenol-containing wastewater, aiming at the practical problems existing in single anaerobic treatment and aerobic treatment.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for treating phenol-containing wastewater by using a double-stage serial batch reactor, wherein the double-stage serial batch reactor comprises a sequencing batch reactor I and a sequencing batch reactor II, wherein the outlet pipe of the sequencing batch reactor I is connected to the inlet pipe of the sequencing batch reactor II, and the method for treating phenol-containing wastewater by using the double-stage serial batch reactor comprises the following steps:

[0007] Step 1, inoculating domesticated activated sludge into both sequencing batch reactor I and sequencing batch reactor II;

[0008] Step 2: passing the phenol-containing wastewater into a sequencing batch reactor I for anoxic treatment and aerobic treatment in sequence. After the aerobic treatment is completed, the wastewater is allowed to settle to separate the mud and water, and the supernatant is discharged;

[0009] Step 3: The supernatant discharged from the sequencing batch reactor I is passed into the sequencing batch reactor II and then subjected to anoxic treatment and aerobic treatment in sequence. After the aerobic treatment is completed, the mixture is allowed to settle to separate the mud and water, and the supernatant is discharged to complete the whole process.

[0010] Furthermore, in step 1, the domesticated activated sludge is activated sludge that is tolerant to phenol after domestication, and the concentration of the activated sludge in the sequencing batch reactor I and the sequencing batch reactor II is 4000-5000 mg / L.

[0011] Furthermore, both the sequencing batch reactor I and the sequencing batch reactor II are provided with a stirring device, and the reactants are stirred during the anoxic treatment and the aerobic treatment.

[0012] Furthermore, both the sequencing batch reactor I and the sequencing batch reactor II are provided with an aeration device, and during aerobic treatment, the aeration volume is the effective volume of the reactor*(0.3-0.4) L / min·L.

[0013] Furthermore, the anoxic treatment time in the sequencing batch reactor I and the sequencing batch reactor II was 4.5 h, and the aerobic treatment time was 17.5 h.

[0014] Furthermore, after the activated sludge is inoculated in the sequencing batch reactor I and the sequencing batch reactor II, they are allowed to stand, and the supernatant of 1 / 2 of the effective volume of the reactor is discharged, and then the phenol-containing wastewater of 1 / 2 of the effective volume of the reactor is introduced into the sequencing batch reactor I.

[0015] Furthermore, the reaction temperature in the sequencing batch reactor I and the sequencing batch reactor II is controlled at 25-28°C.

[0016] Preferably, the effective volume of the sequencing batch reactor I and the sequencing batch reactor II is 6L.

[0017] Furthermore, the COD concentration of the phenol-containing wastewater is 600-2800 mg / L, the total phenol concentration is 200-800 mg / L, the ammonia nitrogen concentration is 60-280 mg / L, and the pH is 7-7.5.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] Phenolic substances are the main source of acute toxicity in coking wastewater. They can also inhibit microbial activity at low concentrations, resulting in unstable treatment effects and low efficiency. The present invention discloses a method for degrading phenolic substances in coking wastewater and reducing biological toxicity using a two-stage series sequencing batch reactor. The method is used to treat phenolic wastewater. After two-stage complete treatment, the effluent COD and total phenols can be removed by more than 95%, and the biological toxicity can be reduced by more than 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 , a schematic diagram of the structure of a two-stage series sequencing batch reactor;

[0021] Figure 2 , the removal effect diagram of COD in phenol-containing wastewater using a two-stage series sequencing batch reactor;

[0022] Figure 3 , the removal effect diagram of total phenol in phenol-containing wastewater using a two-stage series sequencing batch reactor;

[0023] Figure 4 , the removal effect diagram of ammonia nitrogen in phenol-containing wastewater using a two-stage series sequencing batch reactor;

[0024] In the figure, 1, water inlet bucket, 2, sequencing batch reactor I, 3, intermediate water bucket, 4, sequencing batch reactor II, 5, water outlet bucket, 6, pipeline I, 7, peristaltic pump I, 8, stirring device I, 9, aeration device I, 10, pipeline II, 11, peristaltic pump II, 12, pipeline III, 13, peristaltic pump III, 14, stirring device II, 15, aeration device II, 16, pipeline IV, 17, peristaltic pump IV, 18, water inlet / outlet valve, 91, aeration pump I, 92, gas flow meter I, 93, aeration head I, 94, aeration pipeline I, 151, aeration pump II, 152, gas flow meter II, 153, aeration head II, 154, aeration pipeline II. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Embodiment 1:

[0027] The two-stage series sequencing batch reactor comprises a water inlet barrel 1, a sequencing batch reactor Ⅰ2, an intermediate water barrel 3, a sequencing batch reactor Ⅱ4, and a water outlet barrel 5. The water inlet barrel 1 is connected to the upper water inlet of the sequencing batch reactor Ⅰ2 through a pipeline Ⅰ6, and a peristaltic pump Ⅰ7 is arranged on the pipeline Ⅰ6. A stirring device Ⅰ8 and an aeration device Ⅰ9 are arranged inside the sequencing batch reactor Ⅰ2. The middle water outlet of the sequencing batch reactor Ⅰ2 is connected to the intermediate water barrel 3 through a pipeline Ⅱ10, and a peristaltic pump Ⅱ11 is arranged on the pipeline Ⅱ10. The intermediate water barrel 3 is connected to the upper water inlet of the sequencing batch reactor Ⅱ4 through a pipeline Ⅲ12, and a peristaltic pump Ⅲ13 is arranged on the pipeline Ⅲ12. A stirring device Ⅱ14 and an aeration device Ⅱ15 are arranged inside the sequencing batch reactor Ⅱ4. The middle water outlet of the sequencing batch reactor Ⅱ4 is connected to the water outlet barrel 5 through a pipeline Ⅳ16, and a peristaltic pump Ⅳ17 is arranged on the pipeline Ⅳ16.

[0028] Furthermore, the aeration device Ⅰ9 includes an aeration pump Ⅰ91, a gas flow meter Ⅰ92 and an aeration head Ⅰ93. The aeration head Ⅰ93 is arranged at the lower part of the sequencing batch reactor Ⅰ2. The aeration head Ⅰ93 is connected to the aeration pump Ⅰ91 through an aeration pipe Ⅰ94. The gas flow meter Ⅰ92 is installed on the aeration pipe Ⅰ94.

[0029] Furthermore, the aeration device II15 includes an aeration pump II151, a gas flow meter II152 and an aeration head II153. The aeration head II153 is arranged at the lower part of the sequencing batch reactor II4. The aeration head II153 is connected to the aeration pump II151 through an aeration pipe II154. The gas flow meter II152 is arranged on the aeration pipe II154.

[0030] Furthermore, a plurality of water inlet / outlet valves 18 are provided on the side walls of the sequencing batch reactor Ⅰ2 and the sequencing batch reactor Ⅱ4 from top to bottom.

[0031] After the activated sludge is inoculated inside the sequencing batch reactors Ⅰ2 and Ⅱ4 in the two-stage series sequencing batch reactor, the phenol-containing wastewater enters the sequencing batch reactor Ⅰ2, and then undergoes anoxic and aerobic treatments in sequence. After static sedimentation, the supernatant is discharged into the middle water bucket 3, and then is lifted by the peristaltic pump Ⅲ13 and enters the sequencing batch reactor Ⅱ4, and also undergoes anoxic and aerobic treatments in sequence. After static sedimentation, the treated wastewater is discharged. The specific steps are as follows:

[0032] Step 1, inoculating activated sludge in the two-stage reactor: taking activated sludge that has been acclimated and has a certain tolerance to phenol, and inoculating the acclimated activated sludge into sequencing batch reactor I2 and sequencing batch reactor II4. The effective volume of each sequencing batch reactor is 6L, and the activated sludge concentration is 4000-5000mg / L.

[0033] Step 2, the phenol-containing wastewater is passed into the sequencing batch reactor I2 for anoxic treatment: After the sequencing batch reactor I2 and the sequencing batch reactor II4 are inoculated with activated sludge, they are left to stand, and 3L of supernatant must be discharged. Then, 3L of phenol-containing wastewater is passed into the sequencing batch reactor I2, and stirring is started to create an anoxic environment for a total of 4.5 hours.

[0034] Step 3, aeration aerobic treatment in sequencing batch reactor I2: After 4.5 hours of anoxic reaction, aeration was started in sequencing batch reactor I2 while stirring, with an aeration volume of about 2 L / min, and aeration continued for 17.5 hours.

[0035] Step 4, static sedimentation of sequencing batch reactor I2: After 4.5 hours of anoxic reaction and 17.5 hours of aerobic reaction, stirring and aeration are stopped, and static sedimentation is allowed to proceed for about 1 hour to separate mud and water.

[0036] Step 5: Discharge the supernatant from the sequencing batch reactor Ⅰ2: After static sedimentation, 3L of supernatant is discharged into the middle water bucket 3 through the middle valve of the sequencing batch reactor 1 using the peristaltic pump Ⅱ11.

[0037] Step 6, the supernatant is passed into the sequencing batch reactor II4: the supernatant discharged from the sequencing batch reactor I2 collected by the intermediate water bucket 3 in the previous step is lifted by the peristaltic pump III13 and passed into the sequencing batch reactor II4.

[0038] Step 7, the sequencing batch reactor II4 is subjected to anoxic treatment: after the water is introduced in the previous step, the sequencing batch reactor II4 is stirred to create anoxic environment for a total of 4.5 hours.

[0039] Step 8, aeration aerobic treatment in sequencing batch reactor II4: After 4.5 hours of anoxic reaction, aeration was started in sequencing batch reactor II4 while stirring, with an aeration volume of about 2 L / min, and aeration continued for 17.5 hours.

[0040] Step 9, static sedimentation of sequencing batch reactor II4: After 4.5 hours of anoxic reaction and 17.5 hours of aerobic reaction, stirring and aeration are stopped, and static sedimentation is allowed to proceed for about 1 hour to separate mud and water.

[0041] Step 10, the supernatant is discharged from the sequencing batch reactor II4: after static sedimentation, 3L of supernatant is discharged into the final water outlet bucket 5 through the middle valve of the sequencing batch reactor II4 using a peristaltic pump IV17, completing the whole process.

[0042] Specific instructions:

[0043] (1) The inoculated activated sludge was taken from the secondary sedimentation tank sludge of a sewage treatment plant in Harbin, and after specific domestication, the tolerance concentration of phenolic substances was about 150 mg / L or more;

[0044] (2) The phenol-containing wastewater is prepared by diluting crude phenol as the main carbon source. The crude phenol comes from the phenol-ammonia recovery unit of a coal gasification plant in Henan Province. The crude phenol is mainly composed of various phenolic compounds. At the same time, appropriate amounts of ammonium chloride and potassium dihydrogen phosphate are added to provide nitrogen and phosphorus sources, respectively, and a certain amount of mineral salt solution is added to meet the microbial demand for trace elements. The COD concentration of the phenol-containing wastewater is 600-2800 mg / L, the total phenol concentration is 200-800 mg / L, the ammonia nitrogen concentration is 60-280 mg / L, and the pH is 7-7.5;

[0045] (3) The complete reaction process of each reactor is water inlet, anoxic process, aerobic process, static, and drainage. The total process of each stage is 24 hours, and the total process of two stages is 48 hours. The drainage ratio is 0.5, and the total HRT is 96 hours. The reaction time of each stage can be flexibly adjusted according to the actual water quality and treatment effect;

[0046] (4) The reaction temperature is controlled at 25-28°C;

[0047] (5) The two-stage serial batch reactor is an open system. Stirring during the anoxic process will increase the dissolved oxygen concentration, and aerobic aeration will have a certain stripping effect on volatile phenolic substances;

[0048] (6) There are no special requirements for the water inlet method of SBR I2 and SBR II4. When draining water, it is advisable to select the valve in the middle position to ensure that the drainage volume is appropriate;

[0049] (7) When the carbon source of the effluent after treatment by the sequencing batch reactor I2 is too low (COD is about 100 mg / L or less), glucose and other substances can be added to the sequencing batch reactor II4 as co-metabolism substrates to maintain microbial growth and improve the treatment effect. According to actual operating experience, the dosage can be determined by setting the COD content of the influent of the sequencing batch reactor II4 to above 300 mg / L, or the dosage can be flexibly determined according to field experiments;

[0050] (8) Steps 2 to 5 are a primary sequencing batch reactor process, and steps 6 to 10 are a secondary sequencing batch reactor process;

[0051] (9) When the two-stage series sequencing batch reactor is first started, the complete operation steps including step 1 must be carried out. After the start-up is successful, the treatment process can be started directly from step 2;

[0052] (10) After step 5, the phenol-containing wastewater can be introduced into the sequencing batch reactor I2 again for the next cycle of treatment.

[0053] The two-stage serial batch reactor disclosed in the present invention can operate stably and has been continuously operated for more than 180 days. The COD, total phenol and ammonia nitrogen in the influent gradually increase over time, and the treatment effect is stable. Figure 2-4 .

[0054] At present, the influent COD is 2400±300mg / L, the primary effluent COD is 280±30mg / L, the removal rate is 88.33% on average, the secondary effluent COD is 100±20mg / L, the removal rate is 95.83%, indicating that most of the COD in the influent can be removed after primary treatment, and the secondary treatment can further remove the COD in the primary effluent. The total phenol in the influent is 700±100mg / L, the total phenol in the primary effluent is 50±20mg / L, the removal rate is 92.86% on average, the phenol in the secondary effluent is 10±2mg / L, the removal rate is 98.57% on average. The removal capacity of volatile phenols in each stage of the reactor is relatively stable. The influent ammonia nitrogen is 280±20mg / L, the primary effluent ammonia nitrogen is 30±10mg / L, the average removal rate is 89.29%, the secondary effluent ammonia nitrogen is 10±5mg / L, the average removal rate is 96.43%, the overall removal rate tends to be stable, the intermediate treatment effect fluctuates, and after a period of adjustment, the treatment effect can be restored. Overall, the two-stage series AO mode sequencing batch reactor has good tolerance and treatment capacity for phenol-containing toxic wastewater.

[0055] The ability of the two-stage series sequencing batch reactor to reduce the acute biological toxicity of phenol-containing wastewater is shown in Table 1. The acute biological toxicity of wastewater is characterized by the relationship between EC50 and dilution multiple. After anoxic treatment in the first-stage sequencing batch reactor, the acute biological toxicity can be reduced by more than 80%, after complete first-stage treatment, the biological toxicity can be reduced by more than 97%, and after secondary treatment, it can be reduced by more than 98%.

[0056] Table 1 Biological toxicity reduction of two-stage series sequencing batch reactor

[0057]

[0058]

[0059] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for treating phenol-containing wastewater using a two-stage series sequencing batch reactor, characterized in that: The two-stage serial sequencing batch reactor comprises a sequencing batch reactor I and a sequencing batch reactor II, wherein the outlet pipe of the sequencing batch reactor I is connected to the inlet pipe of the sequencing batch reactor II. The method for treating phenol-containing wastewater by using the two-stage serial sequencing batch reactor comprises the following steps: Step 1, inoculating domesticated activated sludge into both sequencing batch reactor I and sequencing batch reactor II; Step 2: passing the phenol-containing wastewater into a sequencing batch reactor I for anoxic treatment and aerobic treatment in sequence. After the aerobic treatment is completed, the wastewater is allowed to settle to separate the mud and water, and the supernatant is discharged; Step 3: The supernatant discharged from the sequencing batch reactor I is passed into the sequencing batch reactor II and then subjected to anoxic treatment and aerobic treatment in sequence. After the aerobic treatment is completed, the mixture is allowed to settle to separate the mud and water, and the supernatant is discharged to complete the whole process.

2. The method according to claim 1, characterized in that: In step 1, the domesticated activated sludge is activated sludge that is tolerant to phenol after domestication, and the concentration of the activated sludge in the sequencing batch reactor I and the sequencing batch reactor II is 4000-5000 mg / L.

3. The method according to claim 1, characterized in that: The sequencing batch reactor I and the sequencing batch reactor II are both provided with a stirring device, and the reactants are stirred during the anoxic treatment and the aerobic treatment.

4. The method according to claim 1, characterized in that: The sequencing batch reactor I and the sequencing batch reactor II are both provided with an aeration device. During aerobic treatment, the aeration volume is the effective volume of the reactor*(0.3-0.4) L / min·L.

5. The method according to claim 1, characterized in that: The anoxic treatment time in the sequencing batch reactor I and the sequencing batch reactor II is 4.5 hours, and the aerobic treatment time is 17.5 hours.

6. The method according to claim 1, characterized in that: After the activated sludge is inoculated in the sequencing batch reactor I and the sequencing batch reactor II, they are left to stand, and 1 / 2 of the supernatant of the effective volume of the reactor is discharged, and then 1 / 2 of the phenol-containing wastewater of the effective volume of the reactor is introduced into the sequencing batch reactor I.

7. The method according to claim 1, characterized in that: The reaction temperature in the sequencing batch reactor I and the sequencing batch reactor II is controlled at 25-28°C.

8. The method according to claim 1, characterized in that: The effective volume of the sequencing batch reactor I and the sequencing batch reactor II is 6L.

9. The method according to claim 1, characterized in that: The phenol-containing wastewater has a COD concentration of 600-2800 mg / L, a total phenol concentration of 200-800 mg / L, an ammonia nitrogen concentration of 60-280 mg / L, and a pH of 7-7.5.

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