The discharge of toxic heavy metals and synthetic dyes into aquatic systems has become a pressing global environmental concern, necessitating the development of sustainable treatment technologies. Photocatalysis is increasingly recognized as a promising approach due to its efficiency and eco-friendly nature, yet most existing studies emphasize photocatalytic performance while neglecting environmental and economic implications. Biochar has recently emerged as an attractive support material owing to its low cost, carbon resource utilization, and favorable adsorption capacity. Nevertheless, the influence of different precursors and synthesis pathways on environmental burdens and production costs remains insufficiently studied. Additionally, so far research is mostly based in the lab, thus the potential impacts from the consequential large-scale application remain unknown. This study aims to conduct a combined life cycle assessment (LCA) and life cycle cost (LCC) analysis of photocatalysts loaded with biochar at an industrial scale. These catalysts are used to degrade hexavalent chromium (Cr(VI)) and Rhodamine B (RhB)—two typical pollutants commonly associated with dye wastewater. The study investigates bismuth tungstate (Bi₂WO₆), titanium dioxide prepared from three precursors [titanium isopropoxide (TTIP), titanium butoxide (TBOT), and commercial P25], and graphitic carbon nitride (g-C₃N₄) synthesized from urea and melamine. The methodological framework integrates environmental impact evaluation, process upscaling, and Aspen Plus simulations, along with economic cost, to provide a comprehensive understanding of both sustainability and feasibility. By comparing these precursor-dependent synthesis routes, the study seeks to identify environmental hotspots, assess process scalability, and explore trade-offs between environmental and economic performance. The outcomes are expected to contribute new insights into the sustainable design of photocatalysts and to support the potential large-scale application of biochar-based composites for industrial wastewater treatment.

Biochar-supported Photocatalysts, Dye Wastewater Treatment, Life Cycle Assessment, Life Cycle Costing, Up-scaling