Refining sludge treatment with alkaline inorganic salt and surfactant

In order to solve a large amount of refining sludge produced in the process of oily wastewater treatment in refinery, the refining sludge was treated by thermochemical-washing, the effects of different types of alkaline inorganic salts and surfactants on the oil removal efficiency of refining sludge were investigated, and the hot washing process conditions were optimized. The results showed that sodium silicate (Na2SiO3) has the best degreasing effect in single hot washing agent, and the degreasing rate was up to 40.3%. Sodium silicate sodium fatty alcohol polyoxyethylene ether sulfate (AES)‍-octylphenol polyoxyethylene ether (OP-10) had the best oil removal rate of 58.2%. The results of orthogonal experiment showed that the influence of chemical hot washing process conditions on oil removal rate was as follows: reagent concentration>hot washing temperature>hot washing time>sludge-water ratio>stirring rate. The optimum operating condition was agent concentration 3g/L, washing temperature 80℃, thermal washing time 60min, stirring speed 300r/min and sludge-water ratio 1:6, the oil removal rate was 75.1%. Gas chromatography analysis showed that the composition of crude oil decreased significantly before and after hot washing, shorter component(C12-C20), medium length component(C21-C30), and longer components(C31-C36)removal rates were 57.8%, 86.2% and 98.0%, respectively. The removal efficiency of long chain alkanes(C31-C36)was the best. After the hot washing agent was reused for 3 times, the oil removal rate was still more than 40.8%. © 2022, Chemical Industry Press Co., Ltd. All right reserved.