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CN-117185566-B - Treatment method and treatment system for wastewater generated in process of extracting phenolic compounds from coal tar

CN117185566BCN 117185566 BCN117185566 BCN 117185566BCN-117185566-B

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a wastewater treatment method and a wastewater treatment system generated in a process of extracting phenolic compounds from coal tar. The treatment method comprises the steps of mixing wastewater with stable gasoline, standing and separating to obtain an upper oil phase and a lower wastewater phase, mixing the wastewater phase with a precipitant to precipitate phosphate in the wastewater phase to obtain a precipitate and a supernatant, deaminizing the supernatant in a distillation mode to obtain ammonia gas and deaminated wastewater, mixing the deaminated wastewater with an extractant to extract to obtain an extract phase and a raffinate phase, rectifying the raffinate phase to obtain qualified biochemical treatment inlet water, and recycling the recovered extractant in the extraction process. The method solves the problems that the treated wastewater still cannot reach biochemical treatment indexes and secondary pollution is generated.

Inventors

  • LIU NING
  • WANG YONG
  • JI RUI
  • SUN JIANGJIANG
  • LIU WEI
  • WANG YANJUN
  • GAO XIANGYU

Assignees

  • 陕西煤业化工集团神木天元化工有限公司

Dates

Publication Date
20260505
Application Date
20231010

Claims (6)

  1. 1. The method for treating the wastewater generated in the process of extracting the phenolic compounds from the coal tar is characterized by comprising the following steps of: Mixing the wastewater with stable gasoline, and standing for separation to obtain an upper oil phase and a lower wastewater phase, wherein the wastewater phase contains oil, pyridine and pyridine derivatives, phenolic compounds, ammonium phosphate and pyridinium phosphate; Mixing the wastewater phase and a precipitator to precipitate phosphate radical in the wastewater phase to obtain precipitate and supernatant; Deamination is carried out on the supernatant liquid in a distillation mode to obtain ammonia gas and deamination wastewater, wherein the deamination wastewater comprises oil, pyridine and pyridine derivatives, phenolic compounds and water; Mixing the deamination wastewater with an extractant for extraction to obtain an extraction phase and a raffinate phase, wherein the extraction phase contains the extractant, oil, pyridine and pyridine derivatives and phenolic compounds; rectifying the raffinate phase to obtain qualified biochemical treatment water; carrying out biochemical treatment on the qualified biochemical treatment water; the pH value of the wastewater is 9-10; the wastewater comprises 150-300 g/L of COD, 1-2 g/L of oil, 50-80 g/L of total phenol, 9.5g/L of ammonia nitrogen and 0.5-15 g/L of phosphate radical, wherein the ammonia nitrogen comprises pyridine, pyridine derivatives and nitrogen in ammonium phosphate salt; The extractant comprises one or more of an ester solvent, a hydrocarbon solvent, an ether solvent and a ketone solvent; The deamination treatment is performed in a deamination system; the temperature of the tower top of the deamination system is 135-150 ℃ and the pressure is 0.3-0.7 MPa; the temperature of the bottom of the deamination system is 148-160 ℃, and the pressure is 0.33-0.73 MPa; The number of the tower plates of the deamination system is 35-45, and the reflux ratio is 2-9.
  2. 2. The treatment method according to claim 1, wherein the mass ratio of the wastewater to the stabilized gasoline is 1 (1-10); the mixing temperature of the wastewater and the stable gasoline is 25-50 ℃, and the pressure is normal pressure.
  3. 3. The process of claim 1, wherein the precipitant comprises calcium hydroxide; The mass ratio of the precipitant to the wastewater phase is (0.3-10) to 100.
  4. 4. A process according to claim 1 or 3, wherein the precipitation temperature is 25 to 80 ℃ and the pressure is 90 to 200kpa; the precipitation is carried out under the condition of stirring, and the stirring speed is 500-3000 r/min.
  5. 5. The process of claim 1, wherein, The mass ratio of the extractant to the deamination wastewater is 1 (1-10).
  6. 6. The method according to claim 1 or 5, wherein the extraction is performed in a rectifying column having a tray number of 70 to 90; the extraction temperature is 25-65 ℃ and the pressure is 90-350 kPa.

Description

Treatment method and treatment system for wastewater generated in process of extracting phenolic compounds from coal tar Technical Field The invention relates to the technical field of wastewater treatment, in particular to a wastewater treatment method and a wastewater treatment system generated in a process of extracting phenolic compounds from coal tar. Background The wastewater generated in the process of extracting phenolic compounds from coal tar mainly comprises oil, pyridine and pyridine derivatives, phenolic compounds, ammonium phosphate salts, pyridinium phosphate salts and the like. At present, the treatment methods of the phenol-containing wastewater mainly comprise a biodegradation method, a solvent treatment method (extraction method), an activated carbon adsorption method, a chemical oxidation method and the like. The biodegradation method is mainly suitable for low-concentration phenol-containing wastewater, phenol and derivatives thereof in high-phenol-containing wastewater have strong toxic action on microorganisms, and the biological activity of the microorganisms is greatly affected, so that the microorganisms are difficult to degrade phenolic organic matters. The extraction method and the active carbon adsorption method have better treatment effect on the high-phenol-content wastewater, but the extraction method has higher requirements on extraction environment and process, the phenol-content wastewater is generally alkaline, and the extraction dephenolization needs to be carried out under acidic conditions, so that a large amount of acid is needed during the extraction, the extraction method needs enough temperature, secondary pollution is easy to generate, the recovery of extractant also needs higher energy consumption, and the active carbon adsorption method has the defects of easy saturation and difficult analysis, high regeneration cost and easy secondary pollution. Industrial wastewater with pyridine and pyridine derivatives as main pollutants usually contains high-concentration salt and ammonia nitrogen, and the long-team biochemical treatment method needs to be diluted in a large amount, and usually the salinity is diluted to be below 0.5%, so that the water treatment amount is increased, the energy consumption is increased, the occupied area of a wastewater treatment system is large, and meanwhile, the degradation efficiency of the traditional biochemical method on the pyridine and pyridine derivative pollutants is low, so that the environment is polluted. Although the distillation concentration method can effectively remove salt, because the boiling point of pyridine and pyridine derivative substances is close to that of water, about 115 ℃, a large amount of pyridine and pyridine derivative substances are distilled along with the water and are difficult to remove, the distilled liquid also contains ammonia nitrogen with a certain concentration, and meanwhile, the treatment of the distilled concentrated liquid is still difficult, and the treatment cost of the method is as high as hundreds of yuan per ton of wastewater, which is not born by most enterprises. The dephosphorization process in the wastewater mainly comprises a precipitation method, a coagulation method, an adsorption method, an ion exchange method, a biological method and the like, but the method still has the problem of high cost. Meanwhile, no method for simultaneously removing oil, pyridine and pyridine derivatives, phenolic compounds, ammonium phosphate salts, pyridinium phosphate salts and the like in the wastewater is available in the prior art, so that deamination wastewater reaches biochemical treatment indexes and secondary pollution is avoided. Disclosure of Invention The invention aims to provide a method and a system for treating wastewater generated in the process of extracting phenolic compounds from coal tar. The treatment method can simultaneously remove oil, pyridine and pyridine derivatives, phenolic compounds, ammonium phosphate and pyridinium phosphate in the wastewater, and solves the problems of malodor caused by the wastewater, high treatment cost, incapability of achieving biochemical treatment indexes and secondary pollution after the wastewater is treated. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a method for treating wastewater generated in a process of extracting phenolic compounds from coal tar, which comprises the following steps: Mixing the wastewater with stable gasoline, and standing for separation to obtain an upper oil phase and a lower wastewater phase, wherein the wastewater phase contains oil, pyridine and pyridine derivatives, phenolic compounds, ammonium phosphate and pyridinium phosphate; Mixing the wastewater phase and a precipitator to precipitate phosphate radical in the wastewater phase to obtain precipitate and supernatant; Deamination is carried out on the supernatant liquid in a dist