The Study On Treatment Technology Of The Coal Chemical Processing Wastewater

Components are complex in coal chemical processing wastewater, including tar, phenols, ammonia, hydrogen sulfide, carbon dioxide and so on. Treating the coal chemical processing wastewater generally requires three steps: chemical and physical treatment, biological treatment and advanced treatment. Among them, chemical and physical treatment results will directly affect biological treatment effect. Using efficient chemical and physical treatment technology can reduce the cost and energy of the entire process. The chemical and physical treatment includes oil separation and dust removal process, deacidification, ammonia removal, and solvent extraction dephenolization process. As every business has different choice of the raw coal quality and process, so the quality of coal wastewater has great difference. We should targeted choose the coal chemical processing wastewater treatment.This paper studied the extraction process of phenols from coal chemical processing wastewater. This research enabled us to confirm MIBK was a good phenols remover. Using MIBK as the extractive agent, at 50 degrees Celsius, phase ratio R=1:4 and after 4-stage extraction, the concentration of total phenols from 9422mg/L to 478 mg/L, with removal percent up to 94.93%, and the COD in wastewater was decreased from 33000mg/L to 2521mg/L, with the removal percent up to 92.36%.Besides, this article has presented the extraction process of oil to treat the coal chemical processing wastewater containing too much oil and dust. Extraction-recovery process of oil was added after oil separation and dust removal process. First, through simulation and studying in the lab, the results enabled us to confirm “toluene :MIBK=1:1” was a good oil remover. The results showed that using “toluene: MIBK=1:1” as the extractive agent, at temperature from 40℃to 60℃,phase ratio R=1:4 and after 4-stage extraction, the COD in wastewater was decreased from 39000mg/L to 9900mg/L, with the removal percent up to 70%and the concentration of total phenols from 6678mg/L to 1335 mg/L, with removal percent up to 80%.In order toreduceenergy consumption, extraction was replacedwiththe resin adsorptionmethodfortreatingthe wastewater after the ammonia stilling. The studyontheadsorptionofphenol and oil was carriedout. The study on the static test of resin adsorption showed the adsorption rate and adsorptive capacity for the organic matter at room temperature. We got out that the resin adsorption capacity for total phenols was 78.6mg/g, with the resin adsorption rate up to 28.90%, and the resin adsorption capacity for COD was 264mg/g, with the resin adsorption rate up to 28.78%. The COD in the third bed volume wastewater has already came to more than 12000mg/L, and the concentration of total phenols has already came to more than1100mg/L. The COD in the forth bed volume wastewater has already came to more than 15000mg/L, and the concentration of total phenols has already came to more than1900mg/L. Thesedataindicated that the selectedresin showedbad adsorptionpropertiesfor phenols, because the bed was penetrated soon. Besides, there would be many oily substances produced which were viscous and black with the decrease in the pH value of the wastewater after the ammonia stilling. There would be more oily substances produced with the pH value decreasing. which might greatly improve the adsorption effect.