An approach integrating waste-derived resources for SiO2 recovery and CO2 mineralization from chemical mechanical polishing sludge

The rapid expansion of the semiconductor industry has led to increased waste generation from chemical mechanical polishing (CMP), a process with the highest water consumption in wafer fabrication. Although wastewater recycling technologies are well established, CMP sludge remains difficult to treat and lacks value-added recycling pathways. In this study, a strategy using waste-derived resources was developed to address this challenge. Waste sulfuric acid from semiconductor processes and cement-based materials from the construction sector were combined to enable simultaneous CMP sludge valorization and CO 2 mineralization. CMP sludge was first leached with waste sulfuric acid, achieving over 99 % SiO 2 recovery with a purity exceeding 99 %. Subsequent treatment of the leachate with cement induced chemical precipitation and neutralization, producing treated water that met Japanese effluent discharge standards. The resulting solid precipitate, mainly CaSO 4 ·2H 2 O, was further carbonated using Na 2 CO 3 , achieving a Ca conversion of 86 % and a CO 2 uptake of 428 mg CO 2 g −1 cement, approximately 2.1 times higher than that obtained using cement alone. Mass balance analysis indicated that treating 100 g of CMP sludge yielded ∼99.5 g of recycled SiO 2 and enabled 50 g of CO 2 uptake potential. These results demonstrate a viable pathway for integrated resource recovery and industrial waste valorization.