Method for extracting and dephenolizing coal chemical industry wastewater

Abstract

The invention discloses a method for extracting and dephenolizing coal chemical industry wastewater. Two different solvents are used as extracting agents, and serially-connected double-tower two-stage extracting dephenolization is adopted. The method comprises the following steps of: after carrying out gravity settling oil removal pretreatment on high-concentration phenol-contained wastewater produced in the coal chemical industry process and deacidifying, deaminizing and removing mechanical impurities, carrying out first-stage extracting dephenolization with the first solvent as the extracting agent; and carrying out second-stage extracting dephenolization with the second solvent as the extracting agent and conveying dephenolized water into a biochemical treatment working section. The wastewater subjected to first-stage dephenolization has the total phenol content of 400-1,000mg / l and the COD (Chemical Oxygen Demand) of 2,000-5,000mg / l; the wastewater subjected to second-stage dephenolization has the total phenol content of smaller than 300mg / l and the COD of smaller than 2,000mg / l; and the total phenol removal rate is larger than 90 percent, and the polyphenol removal rate is larger than 70 percent. The invention can meet the requirement of water quality of biochemical treatment, has the advantages of high phenol removal rate, less solvent dosage and low energy consumption and is particularly suitable for treating the wastewater which has high polyphenol content and is produced in the coal gasification, coking and chemical industry synthesis process.

Description

technical field

[0001] The invention relates to a coal chemical industry and industrial wastewater treatment technology, in particular to a coal chemical wastewater extraction and dephenolization method. Background technique

[0002] Coal chemical wastewater is wastewater produced during coal gasification, dry distillation, purification, and synthesis of chemical products. It has high pollutant concentration and complex composition, including tar, aromatic hydrocarbons, ammonia nitrogen, sulfide, cyanide and other pollutants. One of the most difficult industrial wastewater to treat, it is difficult and costly to treat.

[0003] The total phenol content in coal chemical industry wastewater can be as high as 5000 mg / l or more, and the composition is complex, including both unit phenols and polyphenols. It is one of the main pollutants that must be removed because of its great environmental hazards. But on the other hand, phenol is also an important chemical raw material, whic...

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