Thermal treatment of heavy oily sludge: resource recovery and potential utilization of residual asphalt-like emulsion as a stabilization/solidification material

Abstract

An innovative application of oily sludge via a distillation modification treatment has been proposed. Particular attention was paid to key parameters of the recovered light oil and residual emulsion, including the separation ratio of light oil, the change of chemical composition, values of penetration and softening point of the residual emulsion. In addition, leaching tests were conducted to investigate the effect of modified oily sludge as a material to solidify other hazardous waste on controlling the release of heavy metals. The results showed that the separated light oil was higher than 29.2% of the original dewatered oily sludge, such as 33.4% at 493 K and 39.2% at 573 K for 180 min. In an appropriate range of thermal treatment parameters (distillation temperature 493–533 K and time 2–3 h), the research achieved more desirable results for the residual emulsion. For example, the content of resin and asphaltene in the residual emulsion was increased from 29.1% to 47.5% at 493 K for 180 min. Furthermore, it was found that the values of penetration and softening point of the residual emulsion were 88 and 48.5 °C, respectively. And this modification enhanced its bond capacity. When this asphalt-like emulsion was used as a solidifying or embedding material, an ideal ratio was achieved at 0.5 (m/m) for controlling the release of heavy metals in this study. The results contribute to the development of new technologies relating to the utilization of oily sludge.