Enhanced removal of refractory organic pollutants in wafer surface treatment wastewater by combining Fenton oxidation and O3/H2O2/FeOOH: Removal efficiency, intermediate composition, and toxicity prediction

Wafer surface treatment is a crucial step in the integrated circuit packaging process, which would generate high-strength organic wastewater using propylene glycol monomethyl ether (PGME) as a photoresistor thinner. This study investigated the performance of Fenton oxidation and catalytic ozonation (O 3 /H 2 O 2 /FeOOH) for removing refractory organics in wafer surface treatment wastewater by optimizing operation and combining utilizations. Gas chromatography–mass spectrometry was employed to analyze intermediates composition in the effluents treated by various advanced oxidation processes , and the toxicity of organics was predicted using the Quantitative Structure-Activity Relationship tool. Fenton oxidation outperformed O 3 /H 2 O 2 /FeOOH in the removal efficiencies of chemical oxygen demand (COD) and PGME, but produced 9.60 kg·m −3 of chemical sludge . Additionally, 3-hydroxy- N -phenylaniline, an acutely toxic compound, was dominant in the intermediates of Fenton oxidation, indicating the ecological risks of chemical sludge. O 3 /H 2 O 2 /FeOOH followed by Fenton oxidation (O 3 /H 2 O 2 /FeOOH + Fenton) exhibited higher total organic carbon removal (77.7 %) with less chemical sludge production (8.47 kg·m −3 ) than the reverse combination (Fenton + O 3 /H 2 O 2 /FeOOH). Although the intermediates of aniline, ketone, and ester exhibited considerable acute and developmental toxicity , the significant improvement in biodegradability of the effluents (BOD 5 /COD ratio of 0.36 > 0.02 for raw wastewater) favored subsequent biological treatment. These findings provide guidance for the cost-effective treatment of wafer surface treatment through rational designing combined processes.