Treatment of alkaline wastewater from cleaning of color filter glass

The treatment of alkaline wastewater (noted as A-water) from cleaning of color filter glass (CFG) was studied. The A-water contains hydroxide ion and dissolved acrylic resin of high concentrations of 4 M and 80,446 mg/L chemical oxygen demand (COD), respectively. The suspended solid (SS) of A-water was removed via filtration. The effluent after filtration process (noted as F-water) was further treated via advanced oxidation processes (AOPs) such as ozonation (OZ), OZ/ultra-violet (UV) irradiation (OZ/UV) and catalytic OZ/UV with Pt/γ-Al₂O₃ (OZ/UV/Pt). The filtration process employing 0.5 μm PTFE filter yielded the F-water containing 55,749 mg/L COD with the removal efficiency of COD (η_C) relative to A-water (η_C,FA) of about 30.7% for treating the A-water. It was noted that about 33.7% COD of A-water can be also removed using the gravity sedimentation (GS). However, the GS time was as long as about 7.5 h. The values of η_C relative to F-water (η_C,OF) via AOPs for treating the F-water were about 8-12% at the reaction time of 60 h. The overall η_C relative to A-water (η_C,OA) can reach about 36.2-39.1% after filtration process and AOPs.