In the past, several technologies for the removal of silica particles from chemical mechanical polishing (CMP) or backside grinder (BG) wastewater such as chemical coagulation, electrocoagulation, flotation, membrane filtration, and adsorption. Currently, the successful aggregation technologies by employing magnetic seeds have been reported. This paper assesses the potential for regeneration of used magnetic seeds by ultrasound employed on the treatment of wastewater from the semiconductor industry. The results show that the reuse cycles of magnetic seeds could be increased up to five times for seeds regenerated by ultrasound power of 235 W for 1 min which exhibited the best effect on the regeneration. Furthermore, the reuse cycles of magnetic seeds could be increased up to 12 times using pulsed ultrasound. In this study, the regeneration of magnetic seeds enhanced by using ultrasound could not only increase the reuse cycles of magnetic seeds but also lessen the usages of coagulants and reduce the quantity of chemical waste sludge. It also indicated that such regeneration processes of magnetic seeds enhanced by ultrasound has a high potential as an alternative to chemical and thermal regenerations of magnetic seeds for purposes of reclamation, recycling, and reuse of magnetic seeds, wastewater, and silica particles. (C) 2013 Elsevier B.V. All rights reserved.