Synergistic enhancement of dewatering and Co-recovery of oil and gas from oily scum via integrated Hydrothermal-Mechanical process

To address the challenges of complex composition, high stability, and poor dewaterability of oily scum, this study applied hydrothermal treatment for its processing. The effects of reaction temperature, time, and stirring speed on dewatering performance were investigated, with flash evaporation and mechanical dewatering integrated to enhance treatment. Optimal conditions (170 °C, 30 min) achieved a dewatering efficiency of 66.64%. Analytical techniques including Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS), particle size analysis, and four-component analysis revealed that hydrothermal treatment converted constrained water into free water, markedly improving dewaterability. With increasing temperature, sludge particles became smaller and the surface morphology turned smoother and more compact. Recovered oil mainly contained saturates and aromatics, indicating good quality, while hydrothermal gas was rich in CO₂ and light hydrocarbons, with temperatures above 200 °C favoring hydrogen production. In summary, hydrothermal treatment not only improved the dewatering and solid conversion of oily scum but also facilitated the recovery of high-quality oil.