Abstract
Gallium is a critical material with increasing demand driven by compound semiconductors such as gallium nitride (GaN) and gallium arsenide (GaAs) used in power electronics and optoelectronics and a highly concentrated supply chain, with 98 % of refined production occurring in China. While recycling remains limited, GaAs semiconductor manufacturing generates wastewater that can contain gallium concentrations ranging from 1-35 mg·L?¹, representing an underutilized secondary resource. This study evaluates the technical and economic feasibility of recovering gallium from GaAs semiconductor wastewater across an input range of 10-100 m³·d?¹ using process modelling and a techno-economic analysis comparing two alternative separation routes: ion exchange (IX) and solvent extraction (SX). Using a real-world industrial wastewater composition, IX achieves a higher overall recovery than single-stage SX (80.40 % vs. 62.54 %), which translates into consistently lower levelized costs of gallium. The resulting levelized cost decreases from 563 to 144 €·kg?¹ for IX and from 701 to 161 €·kg?¹ for SX. The results demonstrate that separation step efficiency is the dominant determinant of economic performance and show that gallium recovery from semiconductor wastewater can be economically viable at fab-relevant scale. The analysis provides a proof-of-concept for integrating gallium recovery into semiconductor wastewater management and highlights its potential contribution to resource security and circular material supply.