CN114307591A - Process and device for deep denitrification of petrochemical wastewater - Google Patents
Process and device for deep denitrification of petrochemical wastewater Download PDFInfo
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Abstract
The invention relates to the technical field of petrochemical tail water treatment, and discloses a process and a device for deep denitrification of petrochemical wastewater. The invention can utilize the hydrogen sulfide component in the absorption liquid as an electron donor in the sulfur autotrophic denitrification process, thereby simultaneously removing the hydrogen sulfide component in the waste gas and nitrate pollutants in the petrochemical tail water. Compared with the traditional heterotrophic denitrification process, the method provided by the invention can be used for deep denitrification treatment of low C/N tail water of a petrochemical wastewater treatment plant without adding an exogenous organic carbon source, so that the treatment cost of deep denitrification of petrochemical tail water is greatly reduced.
Description
Technical Field
The invention belongs to the technical field of petrochemical tail water treatment, and relates to a process and a device for deep denitrification of petrochemical wastewater. In particular to a complete set of device for removing hydrogen sulfide gas in petrochemical wastewater and deeply denitrifying tail water.
Background
The production of malodorous gases is one of the prominent features of petrochemical wastewater. As the early petrochemical wastewater treatment plants in China are not provided with gas collecting and deodorizing devices, the whole petrochemical wastewater treatment plants are permeated with malodorous gas, and the physical and mental health of plant workers is seriously influenced. Meanwhile, malodorous gases diffused with wind often have great negative effects on daily life of surrounding residents, and complaints about malodorous gases emitted by petrochemical wastewater treatment plants are frequent. However, with the attention of our country to the control of the malodorous gas of the sewage treatment plant and the general application of the deodorization process, the malodorous gas emission of most domestic petrochemical wastewater treatment plants can meet the national or local standard. The main components of malodorous gas generated by petrochemical wastewater comprise hydrogen sulfide, methanol sulfur, ethanol sulfur, butanol sulfur, methyl sulfide, organic acid and other malodorous substances, wherein the content of the hydrogen sulfide is the highest. According to the gas sampling result of the safety integrated petrochemical sewage treatment plant in the Linyuanchong, the concentration of the hydrogen sulfide gas in the petrochemical wastewater treatment unit is as high as 35.77mg/m3。
Hydrogen sulfide is an inorganic compound of the formula H2S, an acid gas that is malodorous and flammable at ambient temperature. Hydrogen sulfide can generate hydrogen sulfuric acid after being dissolved in water, the hydrogen sulfuric acid is unstable weak acid, and hydrogen sulfide gas can escape again after being heated. Hydrogen sulfide is a potent neurotoxin and is useful for humansThe body mucosa has strong stimulation, and symptoms such as lacrimation, ophthalmalgia, intraocular foreign body sensation, photophobia, blurred vision, watery nasal discharge, throat burning sensation, cough, chest distress, headache, dizziness, hypodynamia, vague consciousness and the like can appear after high-concentration hydrogen sulfide is absorbed in a short time. In severe cases, cerebral edema and pulmonary edema may occur, with very high concentration (1000 mg/m)3Above) can be suddenly coma within seconds, and flash death occurs. Long-term exposure to low concentrations of hydrogen sulfide gas can cause neurasthenia and vegetative nerve dysfunction. The highest allowable concentration of hydrogen sulfide gas emission in the town sewage treatment plant kingdom (protective zone edge) specified in the discharge Standard of pollutants for municipal Sewage treatment plants (GB18918-2002) issued by China is shown in Table 1. TABLE 1 maximum permissible concentration of hydrogen sulfide gas emissions
At present, the hydrogen sulfide gas removal method applied in large-scale industry is mainly wet removal, such as a chemical oxidation method, an alcohol amine solution absorption method, an ionic liquid method, a biological method and the like. Among them, the biological hydrogen sulfide removal process is receiving more and more attention due to its lower operation cost. Compared with a chemical removal process, the biological method generally does not need additional chemical agents, has lower operation cost, and generates much less solid waste than the chemical method, so the biological method is more environment-friendly.
The petrochemical wastewater generally has the characteristic of low C/N (C/N is less than 3), and when the conventional nitrification and denitrification process is used for treating the wastewater, the denitrification process is often restricted due to insufficient organic carbon sources in the wastewater, so that the content of nitrate in effluent exceeds the standard. In the actual operation of the petrochemical wastewater treatment plant, an additional organic carbon source is usually adopted to provide an electron donor for the denitrification process, such as adding methanol, glucose and the like, so that the treatment cost of the petrochemical wastewater is greatly increased. Moreover, if the adding amount of the organic carbon source is not properly controlled, the COD of the effluent water may exceed the standard. In the face of low C/N wastewater, sulfur autotrophic denitrification processesThe process is a better choice. S can be utilized in the process of sulfur autotrophic denitrification2-、S-、HS-And S2O3 2-And the reducing sulfur-containing compound or sulfur elementary substance is used as an electron donor in the denitrification process. Some cheap sulfur-containing ores, such as pyrite, pyrite and natural pyrite, even S in wastewater2-、HS-These contaminants can act as electron donors in the sulfur autotrophic denitrification process. This means that if the nitrate-containing waste water also contains S2-、HS-When the reducing sulfur-containing pollutants are treated, the sulfur autotrophic denitrification process is adopted to remove the water body pollutants together, and the addition of an exogenous organic carbon source is saved or even avoided. Therefore, a process and a complete set of device for removing the hydrogen sulfide gas in the petrochemical wastewater and deeply denitrifying the tail water are provided.
Disclosure of Invention
The invention aims to solve the defects in the prior art mentioned in the background art, and provides a process and a device for deep denitrification of petrochemical wastewater. The device can utilize the hydrogen sulfide gas of the petrochemical wastewater treatment plant as an electron donor in the denitrification process, can simultaneously achieve the purposes of removing the hydrogen sulfide gas of the petrochemical wastewater and deeply denitrifying the tail water, and avoids the addition of an exogenous organic carbon source.
In order to achieve the purpose, the invention adopts the following technical scheme:
a technology for deeply denitrifying petrochemical wastewater is designed, and the technology adopts four units of spraying, mixing, dosing and sulfur autotrophic denitrification, wherein the four units comprise a primary spraying tower, a secondary spraying tower, a primary mixing tank, a secondary mixing tank, a dosing tank and a sulfur autotrophic denitrification deep bed filter, sodium carbonate is added into petrochemical tail water for medicament mixing, absorption of the petrochemical tail water on hydrogen sulfide gas in waste gas is completed through multiple liquid phase circulations, and then deep denitrification of the petrochemical tail water is completed through sulfur autotrophic denitrification. The spraying unit is divided into two stages, the hydrogen sulfide waste gas completes the absorption process of hydrogen sulfide gas in the first-stage spraying tower and the second-stage spraying tower in sequence, and absorption liquid in the spraying tower is petrochemical tail water added with a sodium carbonate medicament. Hybrid unit masterThe method is used for uniformly mixing the absorption liquid and the medicament and the absorption liquid with high hydrogen sulfide content and the absorption liquid with low hydrogen sulfide content. The sodium carbonate is added into the absorption liquid through the dosing tank, so that the absorption efficiency of the absorption liquid sprayed in the spray tower on the hydrogen sulfide waste gas can be improved, and the re-dissipation amount of the hydrogen sulfide gas in the absorption liquid can be reduced. The absorption liquid after the hydrogen sulfide waste gas absorption process is completed, wherein the hydrogen sulfide component comprises H2S (molecular state), S2-、HS-And S formed by oxidation0Fine particles and the like, and the reducing sulfur-containing compounds and sulfur simple substances cooperate with pyrite filler in a subsequent sulfur autotrophic denitrification deep bed filter device to be used as an electron donor in the sulfur autotrophic denitrification process, so that the deep denitrification process of petrochemical tail water is completed, and the final removal of hydrogen sulfide components is also completed. Through the process of sulfur autotrophic denitrification, the hydrogen sulfide component is finally oxidized into nontoxic sulfate, and the nitrate in the petrochemical tail water is finally reduced into nitrogen. The deep bed filter is selected as the reaction device of the sulfur autotrophic denitrification process, because the sulfur autotrophic denitrification bacteria belong to autotrophic bacteria, the generation period is long, the proliferation rate is slow, and the filler in the deep bed filter device and the pores formed by the accumulation of the filler can effectively intercept the sulfur autotrophic denitrification functional bacteria, thereby ensuring the denitrification performance of the sulfur autotrophic denitrification process.
The specific process flow is as follows:
step 1, delivering the treated petrochemical tail water to a primary mixing tank and a pipeline mixer through a first pipeline and a second pipeline respectively, and uniformly mixing the petrochemical tail water entering the primary mixing tank with a sodium carbonate medicament from a dosing tank under the action of stirring equipment;
step 3, enabling the absorption liquid with low hydrogen sulfide content in the step 2) to automatically flow back to the first-stage mixing tank through gravity, mixing the absorption liquid with petrochemical tail water and sodium carbonate medicament again, and conveying the mixture to the second-stage spray tower again to complete liquid phase circulation between the second-stage spray tower and the first-stage mixing tank;
step 4, overflowing the low-hydrogen sulfide content absorption liquid in the primary mixing tank through a first overflow weir to enter a secondary mixing tank, mixing the low-hydrogen sulfide content absorption liquid with reflux liquid from a primary spray tower under the action of stirring equipment, uniformly mixing the low-hydrogen sulfide content absorption liquid and the reflux liquid, and then conveying the mixed liquid to the primary spray tower again to absorb hydrogen sulfide gas in the hydrogen sulfide waste gas of a petrochemical tail water treatment plant to obtain high-hydrogen sulfide content absorption liquid so as to complete liquid phase circulation between the primary spray tower and the secondary mixing tank;
step 5, mixing the absorption liquid with high hydrogen sulfide content in the secondary mixing tank with the petrochemical tail water in the second pipeline in the step 1) through a pipeline mixer by a third pipeline, mixing, then feeding the mixed absorption liquid into a sulfur autotrophic denitrification deep bed filter to complete deep denitrification, and discharging the effluent after deep denitrification treatment through a pipeline;
and 6, sequentially conveying the hydrogen sulfide waste gas from the petrochemical tail water treatment plant to a primary spray tower and a secondary spray tower to complete liquid phase circulating spray absorption in the steps 3) -4), and then discharging the hydrogen sulfide waste gas to the atmosphere or entering a subsequent waste gas treatment process.
The process for deep denitrification of petrochemical wastewater, which is provided by the technical scheme, has the beneficial effects that:
according to the invention, the liquid phase absorption circulation is carried out through the primary spray tower and the secondary mixing tank, and the liquid phase absorption circulation is carried out through the secondary spray tower and the primary mixing tank, so that the hydrogen sulfide component in the secondary mixing tank not only comes from the primary spray tower which carries out the liquid phase absorption circulation with the secondary mixing tank, but also comes from the overflow of the hydrogen sulfide-containing absorption liquid of the primary mixing tank, and the hydrogen sulfide concentration of the absorption liquid in the secondary mixing tank is higher. In contrast, the hydrogen sulfide component in the primary mixing tank only comes from the secondary spray tower, and the concentration of the absorption liquid in the primary mixing tank is far lower than that of the absorption liquid in the secondary mixing tank because the concentration of the gaseous hydrogen sulfide in the secondary spray tower is far lower than that of the gaseous hydrogen sulfide in the primary spray tower. In general, the process flow setting mode enables the absorption liquid with high hydrogen sulfide concentration to absorb the waste gas with high hydrogen sulfide concentration and the absorption liquid with low hydrogen sulfide concentration to absorb the waste gas with low hydrogen sulfide concentration, so that on one hand, the absorption performance of the absorption liquid is fully exerted, and the absorption liquid approaches to the absorption saturation state, on the other hand, the absorption liquid with low hydrogen sulfide concentration is more beneficial to the liquid phase absorption of the waste gas with hydrogen sulfide, and therefore the process flow setting improves the final absorption rate of the hydrogen sulfide component in the waste gas.
Further, the bottom elevation of one-level spray tower and second grade spray tower is unanimous, and the bottom elevation of one-level blending tank and second grade blending tank is unanimous, and the bottom elevation of one-level spray tower is higher than the highest liquid level of second grade blending tank and is not less than 0.5m, and the bottom elevation of second grade spray tower is higher than the highest liquid level of one-level blending tank and is not less than 0.5m, and the highest liquid level of second grade blending tank should be less than one-level blending tank overflow weir height and is not less than 0.2 m. The height difference between different treatment units in the device is set to fully utilize the gravity flow of absorption liquid between different treatment units, and the setting of a lifting water pump between the treatment units and the corresponding energy consumption are reduced.
Further, in the step 1), the adding amount of the sodium carbonate medicament should ensure that the pH value of the petrochemical tail water in the first-stage mixing tank is more than 9, and in the step 5), the flow ratio of the second pipeline and the third pipeline should ensure that the pH value is between 6.5 and 8 after the mixing of the pipeline mixer. The sodium carbonate medicament is added into the petrochemical tail water, so that the absorption capacity of the absorption liquid to the hydrogen sulfide can be improved, and the absorption removal rate of the hydrogen sulfide component in the waste gas is further improved. Meanwhile, sodium carbonate can also be used as an inorganic carbon source in the subsequent sulfur autotrophic denitrification process. The pilot test result of the sewage treatment plant shows that the pH value of the petrochemical tail water is about 6.1, the pH value of the petrochemical tail water in the primary mixing tank is increased from 6.1 to 9.0 by adding sodium carbonate, and the total absorption rate of the two-stage spray tower to the hydrogen sulfide component in the waste gas is increased from 75.3% to 92.6% under the condition that the rest operation conditions are optimal. Under the operating condition of the pilot plant, the pH value of the petrochemical tail water (effluent of the two-stage mixing tank) flowing through the second pipeline is about 8.4. The previous literature research results show that the optimum pH range of the sulfur autotrophic denitrification functional bacteria is 6.5-8. The pH of the petrochemical tail water flowing through the third pipeline (raw petrochemical tail water without sodium carbonate) is slightly lower than the optimal pH interval of the sulfur autotrophic denitrification functional bacteria, and the pH of the petrochemical tail water flowing through the second pipeline is slightly higher than the optimal pH interval of the sulfur autotrophic denitrification functional bacteria, so that the two kinds of petrochemical tail water are mixed in a proper proportion to adjust the proper pH (6.5-8) meeting the requirement of the water inlet of the sulfur autotrophic denitrification deep bed filter.
Furthermore, the deep denitrification process of the sulfur autotrophic denitrification deep bed filter tank is carried out from top to bottom in a gravity-flow mode, the effective volume of a filter tank filling area is 5-8 times of the effective volume of a single mixing tank in a first-stage mixing tank or a second-stage mixing tank, and the height-diameter ratio of the filter tank filling area is 4-5: 1.
Further, in the step 5), the HRT of the deep sulfur autotrophic denitrification bed filter is controlled to be about 4.5 hours, the backwashing time interval is 7-10 days, and the backwashing control conditions of the deep sulfur autotrophic denitrification bed filter are as follows:
a. independent air washing: the strength is 15-20L/(m 2 s), and the time is 2-3 min;
b. air-water combined backwashing: the air washing strength is 13-16L/(m 2 & s), the water washing strength is 2.5-3L/(m 2 & s), and the time is 4-5 min;
c. and (3) single water washing: 6.5-10L/(m 2 s) for 4-5 min.
The pilot test result shows that the HRT of about 4.5h can ensure the stability of the deep bed filter and higher nitrate removal rate, and the nitrate removal rate of the deep bed filter can reach more than 92% when the concentration of the nitrate in the inlet water of the petrochemical tail water is 35 mg/L. Further reducing HRT of the deep bed filter to 3h, and rapidly reducing the nitrate removal rate to below 64%. The key points of controlling the backwashing strength and time of the filter tank are that the filter tank is periodically backwashed to remove filter particles and aged and fallen biological membranes, the permeability of the filter tank is recovered, and the water head resistance of the filter tank is reduced, but the backwashing strength is not too strong, and the time is not too long, so that the biological membranes attached to the filler are prevented from falling off, and the autotrophic denitrification performance is further influenced.
The device for deeply denitrifying petrochemical wastewater is suitable for the process of deeply denitrifying petrochemical wastewater, and comprises a primary spray tower, a secondary spray tower, a primary mixing tank, a secondary mixing tank, a dosing tank and a sulfur autotrophic denitrification deep bed filter; the first-stage spray tower and the second-stage mixing tank form liquid phase circulation of first-stage absorption of hydrogen sulfide gas in the hydrogen sulfide waste gas through a first return pipe and a fourth pipeline, and a first water pump is arranged on the fourth pipeline; the secondary spray tower and the primary mixing tank form a liquid phase circulation for secondary absorption of hydrogen sulfide gas in the hydrogen sulfide waste gas through a second reflux and a fifth pipeline, and a second water pump is arranged on the fifth pipeline; the first overflow weir of the first-stage mixing tank is connected with the second-stage mixing tank through an overflow pipe; the second-stage mixing tank and a second pipeline are converged and mixed through a pipeline mixer through a third pipeline and then flow into the sulfur autotrophic denitrification deep bed filter through a water inlet main pipe, the second pipeline is communicated with petrochemical tail water of a petrochemical wastewater treatment plant, and a third water pump is arranged on the third pipeline; the primary spray tower is connected with a deodorization pipeline of a petrochemical wastewater treatment plant through an air inlet pipe; the gas outlet of the first-stage spray tower is connected with the gas inlet at the bottom of the second-stage spray tower through a first gas outlet pipe; a dosing tank is connected to the primary mixing tank, and a dosing pump is arranged between the dosing tank and the primary mixing tank; the primary mixing tank is connected with a first pipeline, and the first pipeline is communicated with petrochemical tail water of a petrochemical wastewater treatment plant.
Further, the primary spray tower and the secondary spray tower are cylindrical structures, the height-diameter ratio is 4-6: 1, and the size, the inner structure, the outer structure and the operation control parameters of the primary spray tower and the secondary spray tower are the same; three high-pressure spray headers are sequentially arranged at the centers inside the spray towers of the first-stage spray tower and the second-stage spray tower from top to bottom, and the ratio of the total hourly flow of the three high-pressure spray headers to the effective volume of a single spray tower is controlled to be 1: 4-5; a fan for conveying hydrogen sulfide waste gas is arranged on the air inlet pipe at the lower part of the primary spray tower, and the ratio of the hourly air volume of the fan to the effective volume of a single spray tower is controlled to be 50-60: 1. And a second air outlet pipe is arranged at the top of the second-stage spray tower, and a rain-proof plate is fixedly arranged at the top of the second air outlet pipe. The total flow of the spray header and the air quantity of the fan are controlled to ensure the sufficient absorption efficiency of absorption liquid (petrochemical tail water) in the spray tower to the hydrogen sulfide waste gas and ensure the operation economy. Under the operation condition, the absorption rate of the two-stage absorption tower of the first-stage spray tower and the second-stage spray tower to the hydrogen sulfide component in the hydrogen sulfide waste gas can reach more than 92.6 percent, and the emission requirement of the hydrogen sulfide component in the waste gas is completely met.
Furthermore, the primary mixing tank and the secondary mixing tank are square or cylindrical liquid storage tanks, and the sizes and the structures of the primary mixing tank and the secondary mixing tank are the same; the first overflow weirs are arranged on two sides of the upper part of the first-stage mixing tank; the effective volume of a single mixing tank in the first-stage mixing tank or the second-stage mixing tank is 10-15% of the effective volume of a single spray tower in the first-stage spray tower or the second-stage spray tower; the inside of one-level blending tank and second grade blending tank has the mixer of two vertical axes respectively, and the power selection of the inside two mixers of one-level blending tank should guarantee the sodium carbonate medicament of interpolation and petrochemical industry tail water intensive mixing, and the homogeneity of petrochemical industry tail water should be guaranteed in the power selection of the inside two mixers of second grade blending tank. The effective volume of the mixing tank is selected based on considerations of ensuring a low hydrogen sulfide absorption concentration in the absorption liquid and economy. The concentration of hydrogen sulfide in the absorption liquid, the flow of the spray header and the air volume of the fan are main factors influencing the absorption removal rate of the hydrogen sulfide, and the lower concentration of the hydrogen sulfide in the absorption liquid is beneficial to the liquid-phase absorption process of the hydrogen sulfide, which has the common purpose with the process flow. When the effective volume of the mixing tank meets the requirement, the HRT of the circulating absorption liquid in the mixing tank is 25-45 min. Further reducing the effective volume of the mixing tank can cause the increase of the concentration of the hydrogen sulfide in the absorption liquid, thereby reducing the absorption removal rate of the absorption liquid to the hydrogen sulfide component in the waste gas.
Furthermore, a back-flushing exhaust pipe is arranged at the top of the sulfur autotrophic denitrification deep-bed filter, and a second overflow weir and a water outlet pipe connected with a weir groove of the second overflow weir are arranged at the upper part of the sulfur autotrophic denitrification deep-bed filter; a filler zone is arranged in the sulfur autotrophic denitrification deep bed filter, and the height of the filler zone is about 80 percent of the height of the filter reaction zone; the upper part of the filling area is provided with a filter chamber spray head connected with the water inlet main pipe; the lower part of the filling area is provided with porous filter bricks, and the strength of the porous filter bricks can ensure that the porous filter bricks are not damaged under the actions of filling gravity and back washing (air washing and water washing). Permeability of porous filter brickIt should be possible to ensure that after one continuous run, it results in a head loss of less than 0.5 m. The lower part of the porous filter brick is respectively provided with a back-flushing gas distribution device and a back-flushing water distribution device from top to bottom, the back-flushing gas distribution device is connected with a back-flushing gas inlet pipe, and the back-flushing water distribution device is connected with a back-flushing water inlet pipe; and a filtering water outlet pipe is arranged at the bottom of the sulfur autotrophic denitrification deep bed filter. And (4) the absorption liquid containing the hydrogen sulfide components after the absorption of the first-stage spray tower and the second-stage spray tower enters a sulfur autotrophic denitrification deep bed filter for final hydrogen sulfide component removal and denitrification. It is to be emphasized again here that the hydrogen sulfide component of the absorption liquid comprises H2S (molecular state), S2-、HS-And S formed by oxidation0Fine particles, etc. reducing sulfide and sulfur simple substance. The effective volume of the filler zone of the filter is obtained on the basis of a small experiment, and the requirement on the aspect of economy is fully considered on the premise of ensuring that the hydrogen sulfide component in the absorption liquid is effectively removed. The porous filter brick at the bottom of the filler layer is used as a supporting layer of the filler above the porous filter brick, is used for filtering water and is used as a channel for backwashing water and backwashing gas in the backwashing process, so that the porous filter brick needs to meet the requirements of strength and permeability at the same time.
Further, the filler zone adopts a mixed filler of pyrite and quartz; the mass ratio of the pyrite ore to the quartz stone in the filler zone is 1: 1-2, the particle size of the pyrite ore filler is 5-15 mm, and the particle size of the quartz stone filler is 50-100 mm. The hydrogen sulfide component contained in the absorption liquid entering the sulfur autotrophic denitrification deep bed filter tank is not enough to supply the need of the autotrophic denitrification process, so that an additional electron donor needs to be added into the filter tank. A great deal of research results show that the pyrite is a good-quality and cheap electron donor source in the process of the sulfur autotrophic denitrification. FeS is the main component of the pyrite2Which slowly dissolves in water and Fe generated under the action of microbial organic acid2+And S-Can be used as an electron donor in the autotrophic denitrification process. It is to be explained here that Fe2+Can be used as an electron donor in autotrophic denitrification processHowever, the process belongs to the iron autotrophic denitrification process, not the sulfur autotrophic denitrification process. Because the quartz stone filler in the filter tank has the properties of high strength and inertia, the quartz stone filler plays the role of a hard skeleton of the filler layer in the filter tank filler, and is used for ensuring that the filler layer cannot excessively collapse after the pyrite ore is excessively consumed, thereby ensuring the porosity and the permeability of the filler layer of the filter tank in the later operation stage. Meanwhile, the sufficient porosity of the filler layer of the filter also provides sufficient living space for the sulfur autotrophic denitrification functional bacteria attached to the filler, thereby being beneficial to the rapid proliferation of the sulfur autotrophic denitrification functional bacteria in the filler layer and occupying the dominant position. The selection of the particle size of the pyrite filler enables the pyrite filler to have a large enough specific surface area, and the requirements of solid-liquid mass transfer and a sulfur autotrophic denitrifying bacteria attachment space are met. If the particle size of the pyrite is further reduced, the specific surface area of the pyrite can be further increased, but the porosity of the filter bed is reduced, and the filler with the particle size being too small is easily flushed out of the filter during the back flushing process of the filter, so that the filler is lost. The proportion of the ferro-sulphur ore and the quartzite in the filter filling material is selected to meet the requirement of supplying enough electron donors to the sulfur autotrophic denitrification process on one hand, and to ensure the proportion of the quartzite on the other hand, so as to fully play the role of the quartzite as the hard framework of the filter filling material layer. Similarly, in order to make the quartzite filler fully play a role as a hard framework of the filter filler, the particle size of the quartzite filler is obviously larger than that of the pyrite filler.
Compared with the prior art, adopt the device of petrochemical industry waste water degree of depth denitrogenation of this technical scheme, beneficial effect lies in:
(1) the device for deeply denitrifying petrochemical wastewater provided by the invention adopts a mode of absorbing hydrogen sulfide waste gas by two stages of absorption towers in a grading manner, and the process flow of the device is set so that the absorption liquid with high hydrogen sulfide concentration absorbs the high-concentration hydrogen sulfide waste gas, and the absorption liquid with low hydrogen sulfide concentration absorbs the low-concentration hydrogen sulfide waste gas, so that on one hand, the absorption performance of the absorption liquid is fully exerted, the absorption liquid approaches to a saturated absorption state, and on the other hand, the absorption liquid with low hydrogen sulfide concentration is more beneficial to liquid phase absorption of the hydrogen sulfide waste gas, so that the final absorption rate of hydrogen sulfide components in the waste gas is improved. InTest results show that under the optimal operation condition, the absorption rate of the complete set of equipment to the hydrogen sulfide component in the waste gas can reach 92.6%. The concentration of hydrogen sulfide in the waste gas absorbed by the two-stage spray tower is generally lower than 0.5mg/m3The emission requirements are fully met in terms of hydrogen sulfide concentration alone.
(2) The device for deeply denitrifying petrochemical wastewater provided by the invention takes the petrochemical tail water as the absorption liquid of the hydrogen sulfide waste gas, and the hydrogen sulfide components (reductive sulfide and elemental sulfur) in the absorption liquid are taken as the electron donor in the sulfur autotrophic denitrification process, so that the hydrogen sulfide components and nitrate pollutants in the petrochemical tail water can be removed simultaneously. Compared with the traditional heterotrophic denitrification process, the device provided by the invention can be used for deep denitrification treatment of low C/N tail water of a petrochemical wastewater treatment plant without adding an exogenous organic carbon source, so that the treatment cost of deep denitrification of petrochemical tail water is greatly reduced.
(3) The filler in the deep bed filter device and the pores formed by the filler and the filler are accumulated, so that sulfur autotrophic denitrification functional bacteria can be effectively intercepted. The deep bed filter filling material consists of pyrite and quartz. The pyrite is used as a supplement of hydrogen sulfide components in the absorption liquid to provide a stable electron donor for the sulfur autotrophic denitrification process, and the quartzite is used as a hard framework of the packing layer due to higher strength and stability to maintain the porosity of the packing layer of the deep bed filter. The deep bed filter filler composed of the pyrite and the quartzite provides good survival and proliferation conditions for the sulfur autotrophic denitrification functional bacteria, thereby ensuring the denitrification performance of the sulfur autotrophic denitrification process. The pilot test results show that under the optimal operation condition, the deep bed filter device can achieve 100% of removal rate of hydrogen sulfide components in absorption liquid and over 92% of removal rate of nitrate in petrochemical tail water.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic view illustrating the construction of a complete set for deep denitrification of petrochemical wastewater according to the present invention;
labeled as: 1. a first air outlet pipe; 2. a first stage spray tower; 3. a fan; 4. an air inlet pipe; 5. a flashing board; 6. a second air outlet pipe; 7. a high pressure spray header; 8. a secondary spray tower; 9. a first return pipe; 101. a fourth conduit; 102. a fifth pipeline; 11. a first water pump; 12. a dosing box; 13. a dosing pump; 14. a first conduit; 15. a first water pump; 16. a first overflow weir; 17. a blender; 18. second refluxing; 19. a first-stage mixing tank; 20. an overflow pipe; 21. a second-stage mixing tank; 22. a third water pump; 23. a second conduit; 24. a pipeline mixer; 25. a water inlet main pipe; 26. a sulfur autotrophic denitrification deep bed filter; 27. a second overflow weir; 28. a filter chamber spray head; 29. a third pipeline; 30. a filler zone; 31. porous filter bricks; 32. a back-flushing gas distribution device; 33. a backwashing water distribution device; 34. back flushing the exhaust pipe; 35. backwashing the drain pipe; 36. backwashing the air inlet pipe; 37. a water outlet pipe is filtered; 38. and (4) backwashing the water inlet pipe.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," "fourth," and "fifth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The invention will now be further described with reference to the accompanying drawings.
Example 1
The method specifically comprises the following steps: the pilot scale petrochemical wastewater deep denitrification complete equipment is formally operated in a sewage treatment plant area of a certain industrial park in Hebei in 3-8 months in 2020, and tail water of the sewage treatment plant is used as inlet water of the pilot scale equipment. The industrial park sewage treatment plant mainly receives mixed sewage of coking wastewater of an industrial park and domestic sewage of the park, and the quality of inlet and outlet water and the concentration of hydrogen sulfide in a gas-collecting hood of a regulating pond are shown in the table I.
Table-table of quality of inlet and outlet water of industrial park sewage treatment plant and concentration of hydrogen sulfide in gas-collecting channel of regulating tank
According to the national discharge standard of sewage and sludge from urban sewage treatment plants (GB18918-2002), except TN index, the effluent (petrochemical tail water) quality index of the sewage treatment plants in industrial parks meets the first-class B discharge standard.
The pilot-scale petrochemical wastewater deep denitrification device comprises a primary spray tower 2, a secondary spray tower 8, a primary mixing tank 19, a secondary mixing tank 21, a dosing tank 12 and a sulfur autotrophic denitrification deep bed filter 26; the primary spray tower 2 and the secondary mixing tank 21 form a liquid phase circulation of primary absorption of hydrogen sulfide gas in the hydrogen sulfide waste gas through a first return pipe 9 and a fourth pipeline 101, and a first water pump 11 is arranged on the fourth pipeline 101. The secondary spray tower 8 and the primary mixing tank 19 form a liquid phase circulation of secondary absorption of hydrogen sulfide gas in the hydrogen sulfide waste gas through a second reflux 18 and a fifth pipeline 102, and a second water pump 15 is arranged on the fifth pipeline 102. The first overflow weir 16 of the first-stage mixing tank 19 is connected with the second-stage mixing tank 21 through an overflow pipe 20; the second-stage mixing tank 21 and the second pipeline 23 are converged and mixed through a third pipeline 29 and a pipeline mixer 24, and then flow into the sulfur autotrophic denitrification deep bed filter 26 through a water inlet main pipe 25, the second pipeline 23 is communicated with petrochemical tail water of a petrochemical wastewater treatment plant, and a third water pump 22 is arranged on the third pipeline 29; the primary spray tower 2 is connected with a deodorization pipeline of a petrochemical wastewater treatment plant through an air inlet pipe 4; the gas outlet of the first-stage spray tower 2 is connected with the gas inlet at the bottom of the second-stage spray tower 8 through a first gas outlet pipe 1; a dosing box 12 is connected to the primary mixing tank 19, and a dosing pump 13 is arranged between the dosing box 12 and the primary mixing tank 19; the first pipeline 14 is connected to the first-stage mixing tank 19, and the first pipeline 14 is communicated with petrochemical tail water of a petrochemical wastewater treatment plant.
The device has the following process flow:
the treated petrochemical tail water is respectively conveyed to a primary mixing tank 19 and a pipeline mixer 24 through a first pipeline 14 and a second pipeline 23, and the petrochemical tail water entering the primary mixing tank 19 is uniformly mixed with a sodium carbonate medicament from a dosing tank 12.
And secondly, delivering the petrochemical tail water uniformly mixed in the primary mixing tank to a secondary spray tower 8, mixing the petrochemical tail water with the waste gas from the primary spray tower 2 through a high-pressure spray header 7, and absorbing hydrogen sulfide gas in the waste gas to obtain the absorption liquid with low hydrogen sulfide content.
And thirdly, the absorption liquid with low hydrogen sulfide content in the second step automatically flows back to the first-stage mixing tank 19 through gravity, is mixed with the petrochemical tail water and the sodium carbonate medicament again, and is conveyed to the second-stage spray tower 8 again after being mixed, so that liquid phase circulation between the second-stage spray tower 8 and the first-stage mixing tank 19 is completed.
And fourthly, the absorption liquid with low hydrogen sulfide content in the primary mixing tank 19 overflows through the first overflow weir 16 to enter the secondary mixing tank 21, is mixed with the reflux liquid from the primary spray tower 2, is uniformly mixed and then is conveyed to the primary spray tower 2 again, and absorbs the hydrogen sulfide gas in the hydrogen sulfide waste gas of the petrochemical tail water treatment plant to obtain the absorption liquid with high hydrogen sulfide content, so that the liquid phase circulation between the primary spray tower 2 and the secondary mixing tank 21 is completed.
Fifthly, mixing the absorption liquid with high hydrogen sulfide content in the secondary mixing tank 21 with the petrochemical tail water in the second pipeline 23 in the step I through a third pipeline 29 by a pipeline mixer 24, feeding the mixed absorption liquid into a sulfur autotrophic denitrification deep bed filter 26 to complete deep denitrification, and discharging the effluent after deep denitrification treatment through a pipeline 37.
And sixthly, conveying the hydrogen sulfide waste gas from the petrochemical tail water treatment plant to a primary spray tower 2 and a secondary spray tower 8 in sequence to finish the steps of liquid phase circulating spray absorption in the third step to be discharged to the atmosphere or enter a subsequent waste gas treatment process.
The petrochemical tail water is volatilized and the generated hydrogen sulfide gas is sequentially subjected to primary absorption and secondary absorption in the primary spray tower 2 and the secondary spray tower 8. The primary spray tower 2 and the secondary spray tower 8 are identical in size, internal and external structure and operation control parameters. The first-stage spray tower 2 and the second-stage spray tower 8 are cylindrical structures, the height is 2.5m, the diameter is 0.5m, and the height-diameter ratio is 5: 1. The bottom of the first-level spray tower 2 is connected with a fan 3 used for conveying hydrogen sulfide waste gas in the first-level spray tower 2. Three high-pressure spray headers 7 are sequentially arranged at the center of the spray tower from top to bottom, and the total hourly flow of the three high-pressure spray headers 7 is 0.12m3And the ratio of the effective volume of the spray tower to the effective volume of a single spray tower is 1: 4. The air quantity of the fan 3 per hour is 30m3The ratio of the effective volume of the single spray tower to the effective volume of the single spray tower is controlled to be 60: 1. The primary 19 and secondary 21 mixing tanks are identical in size, configuration and other operating parameters, except that the primary mixing tank 19 is provided with a weir 16 and the power of the internal agitator is different. The first-stage mixing tank 19 and the second-stage mixing tank 21 are square or cylindrical liquid storage tanks. The effective volume of a single mixing tank is 75L, which is 15% of the effective volume of a single spray tower. Two vertical axis agitators 17 are provided inside the first-stage mixing tank 19 and the second-stage mixing tank 21, respectively. The power of the two mixers 17 in the first-stage mixing tank 19 is 0.55kW, so that the added sodium carbonate medicament can be fully mixed with the petrochemical tail water, and the work of the two mixers in the second-stage mixing tank 21 can be guaranteedThe rate is 0.37kW, and the homogeneity of the petrochemical tail water can be ensured. The bottom elevations of the first-stage spray tower 2 and the second-stage spray tower 8 are consistent, the bottom elevations of the first-stage mixing tank 19 and the second-stage mixing tank 21 are consistent, the bottom elevation of the first-stage spray tower 2 is 0.6m higher than the highest liquid level of the second-stage mixing tank 21, and the bottom elevation of the second-stage spray tower 8 is 0.6m higher than the highest liquid level of the first-stage mixing tank 19. The highest liquid level of the second-stage mixing tank 21 is 0.3m lower than the height of an overflow weir of the first-stage mixing tank 19. The concentration of the sodium carbonate solution in the sodium carbonate dosing tank is 50g/L, and the dosage is 100 mL/h. The raw water pH of the petrochemical tail water is about 6.1, the pH of the petrochemical tail water in the first-stage mixing tank after the sodium carbonate is added is about 9.0, and the pH of the petrochemical tail water in the pipelines 23 and 29 is about 7.2 after the petrochemical tail water is mixed by the pipeline mixer 25.
The deep denitrification process of the sulfur autotrophic denitrification deep bed filter 26 is carried out from top to bottom in a gravity flowing mode. The diameter of the filler zone 30 of the filter is 0.5m, the height is 2.5m, the height-diameter ratio of the filler zone 30 of the filter is 5:1, and the effective volume is 0.49m 36 times the effective volume of a single mixing tank. The top of the sulfur autotrophic denitrification deep bed filter 26 is provided with a back flush exhaust pipe 34. The upper part of the sulfur autotrophic denitrification deep bed filter 26 is provided with a second overflow weir 27 and a back flush drain pipe 35 connected with the weir groove of the second overflow weir 27. The height of the reaction zone of the sulfur autotrophic denitrification deep-bed filter 26 is 3.1m, and the height of the filler zone 30 is 80 percent of the height of the reaction zone of the sulfur autotrophic denitrification deep-bed filter 26. The upper portion of the packing region 30 is provided with a filter spray header 28 connected to the water inlet manifold 25. The lower part of the filler area 30 is provided with a porous filter brick 31, the compressive strength of the porous filter brick 31 is 25MPa, and the porous filter brick can be ensured not to be damaged under the action of the gravity and back washing (air washing and water washing) of the filler area 30. The pilot test results show that after the porous filter bricks 31 are continuously operated for one week, the head loss caused by the porous filter bricks is not more than 0.3 m. The lower part of the porous filter brick 31 is respectively provided with a back-flushing gas distribution device 32 and a back-flushing water distribution device 33 from top to bottom, the back-flushing gas distribution device 32 is connected with a back-flushing gas inlet pipe 36, and the back-flushing water distribution device 33 is connected with a back-flushing water inlet pipe 38. The bottom of the sulfur autotrophic denitrification deep bed filter 26 is provided with a filtered water pipe 37. The filter filling 30 adopts the mixed filling of the pyrite and the quartz. The total mass of the pyrite ore in the packing zone 30 is 0.2t, the total mass of the quartzite is 0.4t, and the mass ratio is 1: 2.The particle size of the pyrite filler is 5-10 mm, and the particle size of the quartz filler is 50-80 mm. The petrochemical tail water flow entering the sulfur autotrophic denitrification deep-bed filter 26 through the third pipeline 29 is 35L/h, and the petrochemical tail water flow entering the sulfur autotrophic denitrification deep-bed filter 26 through the second pipeline 23 is 100L/h, so that the total water inlet flow of the sulfur autotrophic denitrification deep-bed filter 26 is 135L/h, and the HRT of the sulfur autotrophic denitrification deep-bed filter 26 is 4.5 h. The back flushing time interval of the sulfur autotrophic denitrification deep bed filter 26 is 10 days. The back-washing control conditions of the sulfur autotrophic denitrification deep bed filter 26 are as follows:
1) independent air washing: intensity 15L/(m2 & s), time 3 min;
2) air-water combined backwashing: the air washing strength is 15L/(m2 & s), the water washing strength is 2.5L/(m2 & s), and the time is 4 min;
3) and (3) single water washing: 8L/(m2 · s), time 4 min.
Example 2
The method specifically comprises the following steps: the complete equipment for deep denitrification of industrial scale petrochemical wastewater is formally operated in a sewage treatment plant area of a certain petrochemical park in a continuous port in 2021 and 5 months, and tail water of the sewage treatment plant is taken as inlet water of the complete equipment. The quality of inlet and outlet water and the concentration of hydrogen sulfide in a gas-collecting hood of a regulating pond of a sewage treatment plant in a certain petrochemical park of the Hongkong port are shown in the second table. Meter of water quality of sewage treatment plant and hydrogen sulfide concentration in gas collecting hood of regulating pool
According to the national discharge standard of sewage and sludge from urban sewage treatment plants (GB18918-2002), except TN index, the effluent (petrochemical tail water) quality index of a sewage treatment plant in a certain petrochemical park in a continuous port conforms to the first-level B discharge standard.
The functional unit composition and process flow of this commercial scale plant was exactly the same as the pilot plant of example 1. However, unlike example 1, the spray tower of the industrial scale plant was 21m high,the diameter is 3.5m, and the height-diameter ratio is 6: 1. The total hourly flow of the three high-pressure spray headers 7 in the spray tower is 40m3And the ratio of the effective volume of the spray tower to the effective volume of a single spray tower is 1: 5. The air quantity of the fan 3 per hour is 12000m3The ratio of the effective volume of the single spray tower to the effective volume of the single spray tower is controlled to be 60: 1. The effective volume of a single mixing tank is 30m2And is 15 percent of the effective volume of a single spray tower. The power of two inside mixers 17 of one-level blending tank 19 is 5.5kW, can guarantee the sodium carbonate medicament and the petrochemical industry tail water intensive mixing that add, and the power of two inside mixers of second grade blending tank 21 is 4kW, can guarantee the homogeneity of petrochemical industry tail water. The adding amount of the sodium carbonate solution is 40L/h. The raw water pH of the petrochemical tail water is about 6.2, the pH of the petrochemical tail water in the first-stage mixing tank after the sodium carbonate is added is about 9.1, and the pH of the petrochemical tail water in the pipelines 23 and 29 is about 6.9 after the petrochemical tail water is mixed by the pipeline mixer 25.
The diameter of the filling area 30 of the sulfur autotrophic denitrification deep bed filter 26 is 3.5m, the height is 17.5m, the height-diameter ratio of the filling area 30 of the filter is 5:1, and the effective volume is 135m 36 times the effective volume of a single mixing tank. The height of the reaction zone of the sulfur autotrophic denitrification deep bed filter 26 is 22m, and the height of the filling zone 30 is 80 percent of the height of the reaction zone of the sulfur autotrophic denitrification deep bed filter 26. The compression strength of the porous filter bricks 31 is 60 MPa. The pilot test results show that after the porous filter bricks 31 are continuously operated for one week, the head loss caused by the porous filter bricks is not more than 0.3 m. The total mass of the pyrite ore in the filler 30 is 67t, the total mass of the quartzite is 135t, and the mass ratio is 1: 2. The particle size of the pyrite filler is 10-15 mm, and the particle size of the quartz filler is 60-1010 mm. The flow rate of the petrochemical tail water entering the sulfur autotrophic denitrification deep bed filter 26 through a pipeline 29 is 15m3The petrochemical tail water flow entering the filter chamber through a pipeline 23 is 22m3The total water inlet flow of the filter is 37m3And h, leading the HRT of the sulfur autotrophic denitrification deep bed filter 26 to be 4.5 h. The back flushing time interval of the sulfur autotrophic denitrification deep bed filter 26 is 8 days. The back-washing control conditions of the sulfur autotrophic denitrification deep bed filter 26 are as follows:
1) independent air washing: intensity 15L/(m2 & s), time 2 min;
2) air-water combined backwashing: the air washing strength is 13L/(m2 & s), the water washing strength is 2.5L/(m2 & s), and the time is 4 min;
3) and (3) single water washing: 6.5L/(m2 · s), time 4 min.
The results of the pilot plant of example 1 run for three months and the industrial plant of example 2 run for four months. Table III pilot plant scale plant and results of operation of an industrial scale plant
As can be seen from the effluent water quality data of the sewage treatment plants in the first industrial park and the second industrial park, the main reason for causing the quality TN of the petrochemical tail water not to reach the first-class B standard is that the nitrate content in the effluent is too high, so that the quality of the petrochemical tail water can be improved to the first-class B standard as long as the nitrate content in the petrochemical tail water is effectively reduced. From the data results of table three, it can be seen that the pilot plant scale and industrial scale complete equipment has good absorption and removal rate for the hydrogen sulfide gas in the petrochemical wastewater, and can realize the simultaneous and efficient removal of the hydrogen sulfide component and the nitrate in the petrochemical tail water. And the TN removal rate is mainly realized by the reduction of nitrate, so that the high-efficiency removal of TN in the petrochemical tail water is realized. The reason that the removal rate of COD in the filter tank is low is probably that B/C of the petrochemical tail water is low, so that the COD is difficult to be utilized by heterotrophic denitrifying bacteria and other heterotrophic bacteria, which also means that the denitrification efficiency is ensured by adding exogenous organic carbon sources if the traditional heterotrophic denitrification process is adopted. The complete equipment can realize the efficient denitrification process without adding an exogenous organic carbon source, so that the complete equipment provided by the invention has great advantages and application prospects when being applied to denitrification of low C/N petrochemical tail water.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A process for deep denitrification of petrochemical wastewater is characterized in that the process adopts four units of spraying, mixing, dosing and sulfur autotrophic denitrification, wherein the four units comprise a primary spraying tower (2), a secondary spraying tower (8), a primary mixing tank (19), a secondary mixing tank (21), a dosing tank (12) and a sulfur autotrophic denitrification deep bed filter (26), sodium carbonate reagents are added into petrochemical tail water for mixing, absorption of petrochemical tail water on hydrogen sulfide gas in waste gas is completed through multiple liquid phase cycles, and then deep denitrification of petrochemical tail water and final removal of hydrogen sulfide components in absorption liquid are completed through sulfur autotrophic denitrification;
the specific process flow is as follows:
1) the treated petrochemical tail water is respectively conveyed to a primary mixing tank (19) and a pipeline mixer (24) through a first pipeline (14) and a second pipeline (23), and the petrochemical tail water entering the primary mixing tank (19) is uniformly mixed with a sodium carbonate medicament from a dosing tank (12);
2) uniformly mixing the petrochemical tail water in the primary mixing tank (19) in the step 1) and conveying the petrochemical tail water to a secondary spray tower (8), and mixing the petrochemical tail water with the waste gas from the primary spray tower (2) through a high-pressure spray header (7) to complete the absorption of hydrogen sulfide gas in the waste gas to obtain absorption liquid with low hydrogen sulfide content;
3) refluxing the absorption liquid with low hydrogen sulfide content in the step 2) to a first-stage mixing tank (19) through gravity flow, mixing the absorption liquid with petrochemical tail water and a sodium carbonate medicament again, and conveying the mixture to a second-stage spray tower (8) again to complete liquid phase circulation between the second-stage spray tower (8) and the first-stage mixing tank (19);
4) the absorption liquid with low hydrogen sulfide content in the primary mixing tank (19) overflows through a first overflow weir (16) and enters a secondary mixing tank (21), is mixed with the reflux liquid from the primary spray tower (2), is uniformly mixed and then is conveyed to the primary spray tower (2) again, and absorbs the hydrogen sulfide gas in the hydrogen sulfide waste gas of the petrochemical tail water treatment plant to obtain the absorption liquid with high hydrogen sulfide content, so that the liquid phase circulation between the primary spray tower (2) and the secondary mixing tank (21) is completed;
5) mixing the absorption liquid with high hydrogen sulfide content in the secondary mixing tank (21) with the petrochemical tail water in the second pipeline (23) in the step 1) through a third pipeline (29) by a pipeline mixer (24), feeding the mixed absorption liquid into a sulfur autotrophic denitrification deep bed filter (26) to complete deep denitrification, and discharging the discharged water after deep denitrification treatment through a pipeline (37);
6) and hydrogen sulfide waste gas from a petrochemical tail water treatment plant is sequentially conveyed to a primary spray tower (2) and a secondary spray tower (8) to complete liquid phase circulating spray absorption in the steps 3) -4), and then is discharged to the atmosphere or enters a subsequent waste gas treatment process.
2. The process for the advanced nitrogen removal of petrochemical wastewater according to claim 1, wherein the bottom elevations of the primary spray tower (2) and the secondary spray tower (8) are consistent, the bottom elevations of the primary mixing tank (19) and the secondary mixing tank (21) are consistent, the bottom elevation of the primary spray tower (2) is higher than the highest liquid level of the secondary mixing tank (21) and is not less than 0.5m, the bottom elevation of the secondary spray tower (8) is higher than the highest liquid level of the primary mixing tank (19) and is not less than 0.5m, and the highest liquid level of the secondary mixing tank (21) is lower than the overflow weir height of the primary mixing tank (19) and is not less than 0.2 m.
3. The process for the advanced denitrification of petrochemical wastewater according to claim 1, wherein in step 1), the sodium carbonate agent is added in an amount to ensure that the pH of the petrochemical tail water in the primary mixing tank (19) is more than 9, and in step 5), the flow ratio of the second and third pipelines (23, 29) is ensured to ensure that the pH is between 6.5 and 8 after the pipeline mixer (24) is mixed.
4. The process for the deep denitrification of petrochemical wastewater according to claim 1, wherein the deep denitrification process of the deep sulfur autotrophic denitrification filter (26) is carried out from top to bottom in a gravity-flow mode, the effective volume of a filter filling area is 5-8 times of the effective volume of a single mixing tank in a primary mixing tank (19) or a secondary mixing tank (21), and the height-diameter ratio of the filter filling area is 4-5: 1.
5. The process for the deep denitrification of petrochemical wastewater according to claim 1, wherein in the step 5), the HRT of the deep bed filter (26) is controlled to be about 4.5h, the backwashing time interval is 7-10 days, and the backwashing control conditions of the deep bed filter (26) are as follows:
a. independent air washing: the strength is 15-20L/(m 2 s), and the time is 2-3 min;
b. air-water combined backwashing: the air washing strength is 13-16L/(m 2 & s), the water washing strength is 2.5-3L/(m 2 & s), and the time is 4-5 min;
c. and (3) single water washing: 6.5-10L/(m 2 s) for 4-5 min.
6. The device for the deep denitrification of the petrochemical wastewater is suitable for the process for the deep denitrification of the petrochemical wastewater, which is characterized by comprising a primary spray tower (2), a secondary spray tower (8), a primary mixing tank (19), a secondary mixing tank (21), a dosing tank (12) and a sulfur autotrophic denitrification deep bed filter (26);
the primary spray tower (2) and the secondary mixing tank (21) form liquid phase circulation of primary absorption of hydrogen sulfide gas in the hydrogen sulfide waste gas through a first return pipe (9) and a fourth pipeline (101), and a first water pump (11) is arranged on the fourth pipeline (101);
the secondary spray tower (8) and the primary mixing tank (19) form liquid phase circulation of secondary absorption of hydrogen sulfide gas in the hydrogen sulfide waste gas through a second reflux (18) and a fifth pipeline (102), and a second water pump (15) is arranged on the fifth pipeline (102);
the first overflow weir (16) of the first-stage mixing tank (19) is connected with the second-stage mixing tank (21) through an overflow pipe (20);
the secondary mixing tank (21) and a second pipeline (23) are converged and mixed through a third pipeline (29) and a pipeline mixer (24) and then flow into the sulfur autotrophic denitrification deep bed filter (26) through a water inlet main pipe (25), the second pipeline (23) is communicated with petrochemical tail water of a petrochemical tail water treatment plant, and a third water pump (22) is arranged on the third pipeline (29);
the primary spray tower (2) is connected with a deodorization pipeline of a petrochemical wastewater treatment plant through an air inlet pipe (4);
the gas outlet of the first-stage spray tower (2) is connected with the gas inlet at the bottom of the second-stage spray tower (8) through a first gas outlet pipe (1);
a dosing box (12) is connected to the primary mixing tank (19), and a dosing pump (13) is arranged between the dosing box (12) and the primary mixing tank (19);
the primary mixing tank (19) is connected with a first pipeline (14), and the first pipeline (14) is communicated with petrochemical tail water of a petrochemical wastewater treatment plant.
7. The device for deeply denitrifying petrochemical wastewater according to claim 6, wherein the primary spray tower (2) and the secondary spray tower (8) have cylindrical structures, the height-diameter ratio is 4-6: 1, and the size, the internal structure, the external structure and the operation control parameters are the same;
the three high-pressure spray headers (7) are sequentially arranged at the centers inside the spray towers of the primary spray tower (2) and the secondary spray tower (8) from top to bottom, and the ratio of the total hourly flow of the three high-pressure spray headers (7) to the effective volume of a single spray tower is controlled to be 1: 4-5;
a fan (3) for conveying hydrogen sulfide waste gas is arranged on an air inlet pipe (4) at the lower part of the primary spray tower (2), and the ratio of the hourly air volume of the fan (3) to the effective volume of a single spray tower is controlled to be 50-60: 1;
and a second air outlet pipe (6) is arranged at the top of the second-stage spray tower (8), and a rain-proof plate (5) is fixedly arranged at the top of the second air outlet pipe (6).
8. The apparatus for the advanced nitrogen removal of petrochemical wastewater according to claim 6, wherein the primary mixing tank (19) and the secondary mixing tank (21) are square or cylindrical liquid storage tanks, which are identical in size and structure;
the two sides of the upper part of the first-stage mixing tank (19) are provided with the first overflow weirs (16);
the effective volume of a single mixing tank in the first-stage mixing tank (19) or the second-stage mixing tank (21) is 10-15% of the effective volume of a single spray tower in the first-stage spray tower (2) or the second-stage spray tower (8);
the inside of one-level blending tank (19) and second grade blending tank (21) has mixer (17) of two vertical axes respectively, and the power selection of two inside mixer (17) of one-level blending tank (19) should guarantee the sodium carbonate medicament of interpolation and petrochemical tail water intensive mixing, and the power selection of two inside mixer (17) of second grade blending tank (21) should guarantee the homogeneity of petrochemical tail water.
9. The apparatus for the deep denitrification of petrochemical wastewater according to claim 6, wherein a back-flushing exhaust pipe (34) is arranged at the top of the deep sulfur autotrophic denitrification bed filter (26), and a second overflow weir (27) and a back-flushing drain pipe (35) connected with a weir trough of the second overflow weir (27) are arranged at the upper part of the deep sulfur autotrophic denitrification bed filter (26);
a filler zone (30) is arranged inside the sulfur autotrophic denitrification deep bed filter (26), and the height of the filler zone (30) is about 80 percent of the height of the filter reaction zone;
the upper part of the filling area (30) is provided with a filter chamber spray header (28) connected with the water inlet main pipe (25);
the lower part of the filling area (30) is provided with porous filter bricks (31), the lower parts of the porous filter bricks (31) are respectively provided with a back-washing gas distribution device (32) and a back-washing water distribution device (33) from top to bottom, the back-washing gas distribution device (32) is connected with a back-washing gas inlet pipe (36), and the back-washing water distribution device (33) is connected with a back-washing water inlet pipe (38);
and a filtering water outlet pipe (37) is arranged at the bottom of the sulfur autotrophic denitrification deep bed filter (26).
10. The apparatus for the deep denitrification of petrochemical wastewater according to claim 9, characterized in that the packing zone (30) employs a mixed packing of pyrite and quartzite;
the mass ratio of the pyrite ore to the quartz stone in the filler zone (30) is 1: 1-2, the particle size of the pyrite ore filler is 5-15 mm, and the particle size of the quartz stone filler is 50-100 mm.
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