In-Situ Carbon Recovery from Refractory Organics in Wastewater: A Critical Review

Abstract

Industrial wastewater containing refractory organic pollutants poses serious ecological and public health risks. Conventional mineralization technologies face challenges of carbon emissions and inefficient carbon utilization. Emerging in-situ carbon recovery systems enable synchronous oxidation of organics and reduction of endogenous CO2 into value-added products (e.g., CO, CH3OH and C2H5OH). This review systematically analyses the main technologies, related mechanisms and potential enhancement pathways: photocatalysis, electrocatalysis-advanced oxidation processes (AOPs), photo-electrocatalysis, and piezocatalysis-AOPs. The comprehensive performance is quantitatively evaluated through economic analysis and life cycle assessment (LCA) methodologies. Photocatalytic technology demonstrates suitability for low-concentration wastewater treatment, though its efficiency under anoxic conditions requires further enhancement. Electrocatalysis and piezocatalysis-AOPs systems exhibit superior performance in wastewater remediation with high-concentration contaminants but encounter substantial barriers including elevated operational costs and carbon footprints. Dual economic-environmental dimension analysis reveals that photocatalysis holds remarkable advantages. Whereas piezocatalysis-AOPs coupling technology necessitates mechanical energy harvesting optimization to improve economic-environmental benefits. Electrocatalysis-AOPs coupling technology urgently requires development of non-noble metal catalysts and process intensification strategies. Finally, scaling up the systems is hindered by complex water matrix interference, inefficient product separation, and inadequate reactor design. This review introduces a novel analytical framework that enables the first quantitative comparison of four in-situ carbon recovery technologies through the synergistic integration of techno-economic assessment with LCA. By explicitly bridging mechanistic understanding, sustainability performance and scalability constraints, the review establishes a coherent development pathway for green chemistry applications in carbon resource recovery, offering guidance for technology selection and process optimization.