Removing of Nano-Particles from Semiconductor Wastewater Using a Hybrid Treatment System

Packaging process is one of the main manufacturing steps in the wafer fabrication industries. However, nano-particles would be produced during the packaging process. The produced nano-particle-contained wastewater has characteristics of dark color and high turbidity. Because the nano-particles would usually result in the clogging of the membrane filtration system when it is used for water treatment and reclamation, the application of a pre-treatment system is required to extend the membrane life. The objective of this study was to develop a pre-treatment system for packaging wastewater treatment before membrane system was applied for further water quality improvement. In this laboratory-scale study, a hybrid treatment system containing a chemical coagulation/flocculation followed by ultra-filtration (UF) membrane technology was developed for the wafer fabrication wastewater treatment. The chemical coagulation/flocculation unit was used as the pre-treatment process to improve the efficiency of the following ultra-filtration (UF) membrane system. The packaging wastewater was collected from a wafer fabrication factory and used to evaluate the feasibility of the coagulation/flocculation process on nano-scale particle removal. Results show that approximately 98% of turbidity could be removed at pH 7 when 2.2 mg/L of polyaluminum chloride (PAC) (used as coagulant) and 0.5 mg/L of polyacrylamide (cPAM) (used as flocculant) were added during the coagulation/flocculation process. Results indicate that the coagulation/flocculation is a feasible pre-treatment process for nano-particle removal before UF membrane is applied for further water purification. Results from this study will be helpful in designing a scale-up system for practical applications.