Method for simultaneously enhancing removal and biological treatment effects of halogenated organic matters in coking wastewater based on ionization irradiation

Abstract

The invention provides a method for simultaneously enhancing removal and biological treatment effects of halogenated organic matters in coking wastewater based on ionization irradiation, which comprises the following steps: adding formate and carbon dioxide gas into coking wastewater subjected to ammonia distillation pretreatment, and then introducing the coking wastewater into an irradiation unit for ionization irradiation treatment, the halogenated organic matters in the coking wastewater are degraded; the effluent of the irradiation unit is further introduced into the biological treatment unit, and the COD value of the effluent is further reduced by means of metabolism of microorganisms; according to the method, formate and carbon dioxide gas are introduced into wastewater to regulate and control reaction conditions, so that the types of active species in an irradiation reaction system are regulated and controlled, and effective degradation of halogenated organic pollutants is promoted. Meanwhile, an intermediate product formed in the irradiation process can be used as a carbon source of a biological treatment unit, and the activity and load resistance of subsequent microorganisms are improved, so that the removal of halogenated organic pollutants and the dual enhancement of the biological treatment effect are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental engineering, and in particular to a method for simultaneously enhancing the removal of halogenated organic matter and biological treatment effects in coking wastewater based on ionizing radiation. Background Art

[0002] Coking wastewater, a type of high-concentration organic wastewater generated during the high-temperature dry distillation of coal, features complex water quality, a high pollution load, and typical characteristics such as high toxicity, high color, and high resistance to degradation. It contains large amounts of phenols, cyanides, nitrogen-containing organic compounds, and a variety of difficult-to-degrade halogenated organic pollutants. These halogenated organic compounds have stable molecular structures and are highly toxic. They are not only difficult to remove through conventional physicochemical or biochemical treatment processes, but can also inhibit or even poison subsequent biological treatment systems, severely impacting the normal metabolic activity and removal efficiency of microorganisms. This has become a key bottleneck restricting the advanced treatment of coking wastewater and achieving standard discharge.

[0003] Due to the dual challenges of halogenated organic matter, such as difficult biodegradability and high toxicity, traditional treatment technologies such as coagulation, adsorption, and Fenton oxidation often have problems such as incomplete treatment, high cost, and complex operation.

[0004] Therefore, developing an efficient, economical and environmentally friendly treatment method to effectively remove halogenated organic matter in coking wastewater and improve the treatment capacity of subsequent biological treatment systems has important engineering significance and application value. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the present invention provides a method for simultaneously enhancing the removal of halogenated organic matter and the biological treatment effect in coking wastewater based on ionizing irradiation, which can achieve dual enhancement of the removal of halogenated organic pollutants and the biological treatment effect in coking wastewater, and provides a new, efficient and feasible approach for the deep purification of coking wastewater.

[0006] The specific content of the invention is as follows: In a first aspect, the present invention provides a method for simultaneously enhancing the removal of halogenated organic matter and biological treatment in coking wastewater based on ionizing radiation, comprising: adding formate and carbon dioxide gas to the coking wastewater pretreated with ammonia distillation, and then passing the coking wastewater into an irradiation unit for ionizing irradiation treatment to degrade the halogenated organic matter in the coking wastewater; The effluent from the irradiation unit is further introduced into a biological treatment unit, where the COD value of the effluent is reduced by the metabolism of microorganisms.

[0007] Optionally, in the coking wastewater, the molar ratio of formate to adsorptive halogenated organic matter is 0.1-1.

[0008] Optionally, the carbon dioxide is introduced continuously at a flow rate of 0.01 to 1 m 3 CO2 / hm 3 .

[0009] Optionally, the flow rate of the carbon dioxide is 0.1~10.5m 3 CO2 / hm 3 .

[0010] Optionally, the radiation source of the ionizing radiation treatment is 60 Co、 137 Cs or electron accelerator.

[0011] Optionally, the dose of the ionizing radiation is 1-17 kGy.

[0012] Optionally, the formate salt is sodium formate.

[0013] Optionally, the pH of the coking wastewater pretreated with ammonia evaporation is 7.0-7.5.

[0014] Optionally, the degradation rate of the halogenated organic matter is greater than 70%.

[0015] Optionally, the biological treatment unit includes an aerobic biological treatment unit, an anaerobic biological treatment unit or a facultative biological treatment unit.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention provides a method for simultaneously enhancing the removal of halogenated organic matter and biological treatment effects in coking wastewater based on ionizing irradiation, the method comprising: adding formate and carbon dioxide gas to coking wastewater pretreated with ammonia evaporation, then passing the coking wastewater into an irradiation unit for ionizing irradiation treatment to degrade the halogenated organic matter in the coking wastewater; the effluent from the irradiation unit is further passed into a biological treatment unit, and the COD value of the effluent is further reduced by means of the metabolism of microorganisms; the present invention effectively regulates the types and conversion pathways of free radicals in the reaction system by introducing formate and passing carbon dioxide gas into the ionizing irradiation system; wherein, the introduction of formate causes it to combine with •OH and •H generated by ionizing irradiation to be converted into •CO2; the introduction of carbon dioxide causes the e generated by ionizing irradiation to be converted into aq - It preferentially reacts with CO2 to produce •CO2. Thus, a system with •CO2 as the primary active species is formed. Due to the high selectivity of •CO2, this system can effectively dehalogenate halogenated organic matter in complex coking wastewater. This solves the problem of poor selectivity and low removal efficiency of halogenated organic matter by •OH alone in complex wastewater, achieving an efficient and controllable pollutant degradation process.

[0017] In addition, while the present invention achieves efficient removal of halogenated organic matter, the residual formate in the system and the intermediate products oxalic acid and methanol generated during the irradiation process can be used as a usable carbon source for subsequent biological treatment processes, effectively alleviating the problem of carbon-nitrogen ratio imbalance in coking wastewater during biological treatment, enhancing microbial activity and the system's load resistance, thereby synergistically improving the treatment effect of the biological treatment unit and achieving an organic combination of pollution control and resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A flow chart of a method for simultaneously enhancing the removal of halogenated organic matter and biological treatment effects in coking wastewater based on ionizing radiation provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product that is identical or similar to the present invention and is obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work fall within the scope of protection of the present invention.

[0021] Before describing in detail the method provided by the present invention for simultaneously enhancing the removal of halogenated organic matter and the biological treatment effect in coking wastewater based on ionizing radiation, it is necessary to explain the relevant technologies as follows: As a new advanced oxidation technology, ionizing radiation technology has attracted wide attention in the field of wastewater treatment in recent years. This technology mainly uses high-energy electron beams to irradiate water bodies, exciting water molecules to produce hydroxyl radicals (•OH), hydrated electrons (e aq - ) and hydrogen radicals (•H) and other active species, these active species react with organic pollutants in water to achieve the purpose of removing organic pollutants. aq -The high reaction rate and its concentration are greater than the concentration of halogenated hydrocarbons in water, e aq - It reacts with oxygen to produce superoxide radicals (•O2 - ). Therefore, •OH dominates the degradation of organic pollutants in wastewater. However, •OH is non-selective for the oxidation of most organic compounds. In complex wastewater systems, it is often preferentially consumed by a large number of inorganic or easily degradable organic compounds, resulting in suboptimal degradation of halogenated organic compounds. Furthermore, some halogenated organic compounds have a low reaction rate with •OH, making complete mineralization difficult. Therefore, irradiation oxidation treatment methods that rely on •OH have difficulty achieving efficient removal of halogenated organic compounds in coking wastewater.

[0022] To address the aforementioned issues, the present invention provides a method based on ionizing irradiation for simultaneously enhancing the removal of halogenated organic matter and the biological treatment of coking wastewater. This method regulates reaction conditions by introducing formate and carbon dioxide gas into the wastewater to control the types of active species in the irradiation reaction system and promote the effective degradation of halogenated organic pollutants. Furthermore, the intermediate products in this system (such as methanol and oxalic acid) can serve as carbon sources for the biological treatment unit, enhancing the activity and load resistance of subsequent microorganisms, thereby achieving dual enhancement of halogenated organic pollutant removal and biological treatment effectiveness, providing a new, efficient and feasible approach for the deep purification of coking wastewater. Specific implementation methods are as follows: In a first aspect, the present invention provides a method for simultaneously enhancing the removal of halogenated organic matter and biological treatment effects in coking wastewater based on ionizing radiation. Figure 1 The flowchart of the method for simultaneously enhancing the removal of halogenated organic matter and biological treatment effect in coking wastewater based on ionizing radiation provided by an embodiment of the present invention is shown as follows: Figure 1 As shown, the method includes: S1. Adding formate and carbon dioxide gas to the coking wastewater pretreated with ammonia distillation, and then passing the coking wastewater into an irradiation unit for ionizing irradiation treatment to degrade the halogenated organic matter in the coking wastewater; It should be noted that the present invention performs deep purification treatment on the coking wastewater after ammonia evaporation pretreatment, and the ammonia evaporation pretreatment is used to remove high-concentration free ammonia nitrogen (NH3-N) in the wastewater. The pH value of the solution of the coking wastewater after ammonia evaporation pretreatment is 7.0-7.5.

[0023] The present invention effectively regulates the types of free radicals and the conversion paths in the reaction system by introducing formate and introducing carbon dioxide gas into the ionizing irradiation system; wherein, the introduction of formate causes it to combine with •OH and •H generated by ionizing irradiation and convert them into •CO2; the introduction of carbon dioxide causes the e generated by ionizing irradiation to aq -It preferentially reacts with CO2 to produce •CO2. Thus, a system with •CO2 as the main active species is formed. Due to the high selectivity of •CO2, it can effectively dehalogenate halogenated organic matter in coking wastewater, with a degradation rate of halogenated organic matter exceeding 55%.

[0024] In specific implementation, the radiation source for ionizing radiation treatment can be 60 Co、 137 Cs or electron accelerator, the amount of formate added to the coking wastewater is a molar amount related to the concentration of halogenated organic matter, and the concentration of halogenated organic matter is based on the adsorbable organic halogen. In the method provided by the embodiment of the present invention, the amount of formate added is controlled to have a mass ratio of 0.5 to 2 to the adsorbable halogenated organic matter contained in the coking wastewater; the adsorbable halogenated organic matter contained in the wastewater is calculated based on the molecular weight of chlorine atoms, and the amount of formate added is controlled to have a molar ratio of 0.1 to 1 to the adsorbable halogenated organic matter.

[0025] Furthermore, the carbon dioxide is introduced continuously with a flow rate between 0.01 m 3 CO2 / hm 3 ~1 m 3 CO2 / hm 3 ; The preferred flow rate is 0.1 m 3 CO2 / hm 3 ~0.5 m 3 CO2 / hm 3 .

[0026] In some embodiments, the formate salt is specifically selected from sodium formate.

[0027] In some embodiments, the dose of ionizing radiation is 1 to 17 kGy.

[0028] S2. The effluent from the irradiation unit is further introduced into a biological treatment unit to reduce the COD value of the effluent by means of the metabolism of microorganisms.

[0029] In practice, the irradiated effluent contains residual formate and intermediate products such as methanol and oxalic acid generated during the irradiation process. These can serve as a usable carbon source for the microorganisms in the biological treatment process, enhancing the biodegradability of the wastewater and improving microbial activity and load resistance. Through microbial metabolism, the COD value of the effluent from the biological treatment unit is significantly reduced.

[0030] It should be noted that the present invention does not limit the specific process of biological treatment, and the selected biological treatment unit can be an aerobic biological treatment unit, an anaerobic biological treatment unit, or a facultative biological treatment unit.

[0031] In order to enable those skilled in the art to more clearly understand the present invention, the method of the present invention for simultaneously enhancing the removal of halogenated organic matter and biological treatment effects in coking wastewater based on ionizing radiation is now described in detail through the following examples.

[0032] Example 1 Ammonia distillate wastewater from a coking wastewater treatment plant in Hebei Province was collected with a pH of 7. The concentration of adsorbable organic halogens (AOX) in the wastewater was 34 mg / L, COD was 2765 mg / L, and the BOD5 / COD (B / C) ratio was 0.07.

[0033] Sodium formate was added to the wastewater to a concentration of 0.25 mmol / L (17 mg / L), and carbon dioxide gas was continuously introduced at a flow rate of 0.06 m 3 CO2 / hm 3 Then it is passed into the irradiation unit and treated with electron beam irradiation at a dose of 4 kGy. After irradiation treatment in the irradiation unit, the effluent enters the aerobic sludge treatment unit.

[0034] In Example 1, after irradiation treatment by the irradiation unit, the AOX concentration in the effluent was 19 mg / L, and the B / C ratio of the wastewater increased by 0.23; the COD of the effluent from the aerobic sludge treatment unit was 214 mg / L.

[0035] Example 2 Ammonia distillate wastewater from a coking wastewater treatment plant in Hebei Province was collected with a pH of 7. The concentration of adsorbable organic halogens (AOX) in the wastewater was 34 mg / L, COD was 2765 mg / L, and the B / C ratio was 0.07.

[0036] Sodium formate was added to the wastewater to a concentration of 0.54 mmol / L (36.7 mg / L), and carbon dioxide gas was continuously introduced at a flow rate of 0.08 m 3 CO2 / hm 3 Then it is passed into the irradiation unit and treated with electron beam irradiation at a dose of 4 kGy. After irradiation treatment in the irradiation unit, the effluent enters the aerobic sludge treatment unit.

[0037] In Example 2, the AOX concentration in the effluent after irradiation treatment in the irradiation unit was 14 mg / L, and the B / C ratio of the wastewater increased by 0.24; the COD of the effluent from the aerobic sludge treatment unit was 201 mg / L.

[0038] Example 3 Ammonia distillate wastewater from a coking wastewater treatment plant in Hebei Province was collected with a pH of 7. The concentration of adsorbable organic halogens (AOX) in the wastewater was 34 mg / L, COD was 2765 mg / L, and the B / C ratio was 0.07.

[0039] Sodium formate was added to the wastewater to a concentration of 0.54 mmol / L (36.7 mg / L), and then carbon dioxide gas was introduced at a flow rate of 0.18 m 3 CO2 / hm 3 Then it is passed into the irradiation unit and treated with electron beam irradiation at a dose of 4 kGy. After irradiation treatment in the irradiation unit, the effluent enters the aerobic sludge treatment unit.

[0040] In Example 3, after irradiation treatment by the irradiation unit, the AOX concentration in the effluent was 9 mg / L, and the B / C ratio of the wastewater increased to 0.29; the COD of the effluent from the aerobic sludge treatment unit was 201 mg / L.

[0041] Example 4 Ammonia distillate wastewater from a coking wastewater treatment plant in Hebei Province was collected with a pH of 7. The concentration of adsorbable organic halogens (AOX) in the wastewater was 34 mg / L, COD was 2765 mg / L, and the B / C ratio was 0.07.

[0042] Sodium formate was added to the wastewater to a concentration of 0.8 mmol / L (54.4 mg / L), and then carbon dioxide gas was introduced at a flow rate of 0.36 m 3 CO2 / hm 3 Then it is passed into the irradiation unit and the wastewater is treated by electron beam irradiation with an irradiation dose of 6 kGy. After irradiation treatment by the irradiation unit, the effluent enters the aerobic sludge treatment unit.

[0043] In Example 4, after irradiation treatment by the irradiation unit, the AOX concentration in the effluent was 4 mg / L, and the B / C ratio of the wastewater increased by 0.35; the COD of the effluent from the aerobic sludge treatment unit was 134 mg / L.

[0044] Comparative Example 1 Ammonia distillate wastewater from a coking wastewater treatment plant in Hebei Province was collected with a pH of 7. The concentration of adsorbable organic halogens (AOX) in the wastewater was 34 mg / L, COD was 2765 mg / L, and the B / C ratio was 0.07.

[0045] The wastewater is passed into the irradiation unit and treated with electron beam irradiation at a dose of 4 kGy. After irradiation treatment, the effluent enters the aerobic sludge treatment unit for biological treatment.

[0046] In Comparative Example 1, the B / C ratio of the effluent after irradiation treatment in the irradiation unit increased to 0.17; the COD of the effluent from the aerobic sludge treatment unit was 247 mg / L.

[0047] By comparing the above results, it can be found that compared with Comparative Example 1, in Examples 1-4, for the coking wastewater after ammonia steam pretreatment, when formate was added and carbon dioxide was introduced, the AOX concentration and COD value in the effluent treated by ionizing irradiation in the irradiation unit were lower, and the biodegradability of the effluent was better; after the effluent of the irradiation unit was further biologically treated in the aerobic sludge treatment unit, its effluent COD value was still lower than that of Comparative Example 1; this shows that the introduction of formate and the introduction of carbon dioxide gas into the coking wastewater after ammonia steam pretreatment can achieve the purpose of simultaneously enhancing the removal of halogenated organic matter and the biological treatment effect in the coking wastewater.

[0048] It can be seen that the method provided by the embodiment of the present invention can efficiently decompose halogenated organic matter in ammonia evaporation coking wastewater. After treatment with ionizing radiation coupled with formate and carbon dioxide, the biodegradability of the wastewater is enhanced, which effectively improves the treatment effect of the subsequent biological treatment process, has good treatment effect and low economic cost.

[0049] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0050] For simplicity of description, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited by the order of the actions described, as certain steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in this specification are preferred embodiments, and the actions and components involved are not necessarily required for the present invention.

[0051] The above is a detailed introduction to a method provided by the present invention for simultaneously enhancing the removal of halogenated organic matter and the biological treatment effect in coking wastewater based on ionizing irradiation. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for simultaneously enhancing the removal of halogenated organic matter and biological treatment effects in coking wastewater based on ionizing radiation, characterized in that: The method comprises: adding formate and carbon dioxide gas to the coking wastewater pretreated with ammonia distillation, and then passing the coking wastewater into an irradiation unit for ionizing irradiation treatment to degrade the halogenated organic matter in the coking wastewater; The effluent from the irradiation unit is further introduced into a biological treatment unit, where the COD value of the effluent is reduced by the metabolism of microorganisms.

2. The method according to claim 1, characterized in that In the coking wastewater, the molar ratio of formate to adsorbable halogenated organic matter is 0.1-1.

3. The method according to claim 1, characterized in that The carbon dioxide is introduced continuously at a flow rate of 0.01 to 1 m 3 CO2 / hm 3 .

4. The method according to claim 3, characterized in that The flow rate of the carbon dioxide in the coking wastewater is 0.1~10.5m 3 CO2 / hm 3 .

5. The method according to claim 1, wherein The radiation source of the ionizing radiation treatment is 60 Co、 137 Cs or electron accelerator.

6. The method according to claim 1, characterized in that The dose of the ionizing radiation is 1-17 kGy.

7. The method according to claim 1, characterized in that The formate is sodium formate.

8. The method according to claim 1, characterized in that The pH of the coking wastewater pretreated with ammonia distillation is 7.0-7.

5.

9. The method according to claim 1, characterized in that The degradation rate of the halogenated organic matter is greater than 70%.

10. The method according to claim 1, characterized in that The biological treatment unit includes an aerobic biological treatment unit, an anaerobic biological treatment unit or a facultative biological treatment unit.

Images