Life Cycle Assessment of Sediment Remediation and Circular Management: A Systematic Methodological Review Towards Improved Comparability

Sediment remediation and circular management can reduce ecological risk and recover resources, but may shift burdens to energy, materials, transport, and residual-stream management. Life cycle assessment (LCA) can reveal these trade-offs, yet published sediment LCAs often model non-equivalent functions and use inconsistent functional units, counterfactuals, boundaries, databases, allocation rules, and circularity credits. This systematic methodological review examines how these choices restrict comparison. A predefined Scopus search and PRISMA-based selection identified 53 studies and 185 management pathways nested within studies. Reporting completeness was assessed across six domains: functional unit and boundaries, foreground-data provenance, background database and version, LCIA reporting, allocation and cut-off rules, and interpretation robustness. Product-oriented cradle-to-gate and remediation-oriented cradle-to-grave studies frequently addressed different functions; contribution, sensitivity, and uncertainty analyses were inconsistently reported. Climate change and resource or energy use were the most frequently decision-relevant categories, but outcomes depended on energy supply, transport, binders, chemicals, water management, substitution assumptions, and residue fate. Circular pathways were widespread, whereas explicit avoided-burden modeling was less frequent. No universal technology ranking was supported. A proposed methodological framework links sediment management function to reference flows, counterfactuals, complete management-chain boundaries, traceable inventories, auditable allocation and substitution, and targeted robustness analyses.