Oily sludge treatment in subcritical and supercritical water: A review

Zhong Chen; Zhijian Zheng; Chunlan He; Jumei Liu; Rui Zhang; Qiao Chen

doi:10.1016/j.jhazmat.2022.128761

Oily sludge treatment in subcritical and supercritical water: A review

J Hazard Mater. 2022 Jul 5:433:128761. doi: 10.1016/j.jhazmat.2022.128761. Epub 2022 Mar 24.

Authors

Zhong Chen¹, Zhijian Zheng², Chunlan He³, Jumei Liu⁴, Rui Zhang⁵, Qiao Chen⁶

Affiliations

¹ Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China. Electronic address: chenzhong@cigit.ac.cn.
² State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China.
³ Chongqing Institute for Food and Drug Control, Chongqing 401120, China.
⁴ School of Petroleum and Natural Gas Engineering, Chongqing University of Science and Technology, Chongqing 401331, China.
⁵ Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
⁶ Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China. Electronic address: chenqiao@cigit.ac.cn.

PMID: 35364539
DOI: 10.1016/j.jhazmat.2022.128761

Abstract

Oily sludge, an inherent byproduct of the petroleum industry, presents dual characteristics of petroleum resources and hazardous waste. Owing to the unique physicochemical properties of sub-/supercritical water, hydrothermal technologies have been increasingly used for oily sludge treatment. This review is the first to focus on oily sludge treatment using sub-/supercritical water. Eight hydrothermal technologies used for different purposes are summarized herein: pressurized hot water extraction (PHWE) for hydrocarbon separation, thermal hydrolysis (TH) for dewaterability improvement, hydrothermal carbonization (HTC) for hydrochar production, wet air oxidation (WAO) for biodegradability improvement, hydrothermal liquefaction (HTL) for bio-oil production, supercritical water upgrading (SCWU) for light oil production, supercritical water oxidation (SCWO) for complete degradation, and supercritical water gasification (SCWG) for H₂-rich syngas production. Moreover, a general reaction pathway for sub-/supercritical water treatment of oily sludge is presented, with a particular focus on the chemical mechanism at temperatures above 350 °C. Lastly, two reaction maps are included to illustrate the reaction pathways of two groups of identifiable model compounds in oily sludge: aliphatic and aromatic hydrocarbons. This review provides detailed information that can promote a better understanding of various hydrothermal technologies, a guideline for selecting the suitable hydrothermal process for a particular oily sludge, and recommendations for further researches.

Keywords: Fuel recovery; Harmless treatment; Hydrothermal technology; Long-chain alkanes; Polycyclic aromatic hydrocarbons; Reaction pathways.

Publication types

Review
Research Support, Non-U.S. Gov't

MeSH terms

Hydrocarbons
Oils
Petroleum*
Sewage* / chemistry
Temperature

Substances

Hydrocarbons
Oils
Petroleum
Sewage