A Review of Innovative Methods for Recycling Oily Sludge: Technological Advances, Challenges, and Environmental Benefits Publisher



Taherkhani S ; Dehghani MH ; Khani A ; Mahvi AH ; Yaghmaian K ; Momeniha F
Source: Desalination and Water Treatment Published:2025

Abstract

Oily sludge, a complex and hazardous by-product of petroleum operations, poses major environmental and economic challenges due to its high hydrocarbon, heavy metal, and water content. Recycling this waste into valuable products has become a strategic priority for sustainable waste management and resource recovery. To provide a comprehensive synthesis of recent advances, a systematic review was conducted in accordance with PRISMA guidelines, covering studies published between January 2015 and April 2025 in PubMed, Scopus, and Web of Science. From 1464 initial records, 179 studies were included after full-text screening and quality appraisal using a modified CASP checklist. Evidence indicates that catalytic pyrolysis, bioremediation, and green solvent extraction are the most extensively investigated approaches. Reported hydrocarbon recoveries ranged from 80 % to 95 %, with pyrolysis achieving high oil yield but accompanied by elevated energy demand and concentration of metals in char, whereas bioremediation offered lower environmental impacts at the expense of longer treatment times. Solvent-based and hybrid systems demonstrated promising recovery rates with variable techno-economic feasibility depending on process integration. This review highlights the need for standardized sludge characterization, integration of life cycle assessment, and development of modular, AI-assisted hybrid systems. The synthesis presented provides novel insights by combining technical, economic, and environmental dimensions to guide future research and industrial applications. © 2025 Elsevier B.V., All rights reserved.