Spiking test-based evaluation of semiconductor wastewater reuse process under shock-loading conditions: removal of TMAH and metal(loid) contaminants

Stable treatment performance is essential for semiconductor wastewater reuse systems under shock-loading conditions. This study evaluated the removal behavior of tetramethylammonium hydroxide (TMAH) and selected metal(loid)s in a lab-scale semiconductor wastewater reuse system consisting of coagulation-flocculation (CF), granular activated carbon adsorption (GAC), cation exchange resin (CEX), anion exchange resin (AEX), ultrafiltration (UF), and reverse osmosis (RO). Unit process tests using real semiconductor wastewater spiked at 5, 50, and 500 mg/L were conducted to investigate specific contaminant removal behavior. TMAH showed negligible removal in CF, GAC, AEX, and UF, whereas CEX and RO showed high removal performance. For the metal(loid)s, CEX and RO were also effective for most target contaminants, while B showed limited removal in the ion exchange processes. The final effluent concentration of TMAH remained low at 1.4 mg/L even under 500 mg/L spiking, whereas Ca and B showed relatively higher residual concentrations of 4.1 and 4.3 mg/L. In the recirculation scenarios, two cycles of RO reduced all target substances to below 0.8 mg/L, while the combined GAC+CEX configuration operated for three cycles was predicted to achieve concentrations below 0.5 mg/L. These results show that the proposed configurations have strong practical potential for semiconductor wastewater reuse systems.