The Treatment Of Waste Lye From Gasoline Alkaline Washing Process:the Phenol Recovery And Raffinate Biological Treatment

It is necessary to wash the liquefied petroleum gas and gasoline with lye (sodium hydroxide solution for example) in the petroleum refining process to obtain refined oil products. The waste caustic sludge contains high concentration of sulfides, phenols, and oil, it is difficult to be disposed. Starting from the point of view of the circular economy, if the economic value of the components are separated by suitable methods, not only can reduce the concentration of pollutants in the spent caustic, but also will be considerable economic benefits. The FCC gasoline caustic refining waste caustic sludge is the object of study, we try to reduce the organic matter of the waste caustic sludge by neutralization and complexation extraction, providing a basis for further biological treatment of waste caustic sludge.Tributyl phosphate is used as a complexing agent, the phenols in waste caustic sludge is extracted with complex extraction method, and the attrition rate of extraction agent is investigated with multi-level cross-flow process. The laminar flow interface-constant pool is used to investigate the impact of the factors such as speed, interfacial area, temperature, initial phenol concentration, and the extraction process control mode is studied.The experiments show that:the initial pH is below8, the temperature is20to30℃, and the volume fraction of tributyl phosphate is from25to30%, the extraction rate of the phenolic compounds arrives at least98%The stripping extraction rate of phenol is over90%when the concentration of sodium hydroxide is10%. the temperature of back-extraction of phenol is50℃and stripping ratio is1:1. During the extraction process, the loss rate of extractant is less than0.1%, the extraction ratio is more than97%while the tri-butyl phosphate is used10times. Kinetic study of tributyl phosphate extraction of phenolic compounds shows that the phenolic extraction process is a diffusion-controlled process, the derived kinetic equation is R=kf1[ArOH(w)]·[TBP(o)]-kb[ArOH(o)], and the extracted reaction is to an first order reversible reaction.The best experimental condition is obtained by the biological treatment of extracted waste caustic sludge with the sequencing batch reactor (SBR). At the condition of a temperature of27±2℃, pH value between7.0to8.5, DO of2～4mg/L, we make a successful acclimation of activated sludge with the phenol and waste caustic sludge as carbon source, and the effect of biodegradation of organic matter is stabile. while the influent COD concentration is500mg/L, the effluent COD concentration is about120mg/L, and the COD removal efficiency is more than76%, the whole system runs well.The biochemical system of SBR reactor is at a certain degree of salt tolerance, When the salt content is60g/L, and the effluent COD stays160mg/L, the COD removal efficiency remains above65%.