一般處理化學機械研磨廢水（CMP wastewaters）須添加大量混凝劑，如此會產生大量污泥，並且所使用之混凝劑無法再次利用，因而提高廢水處理成本及環境上之負荷。本研究群前期已利用自行製備的氧化鐵奈米顆粒（Fe3O4），以磁種凝絮法處理化學機械研磨（CMP）廢水中的奈米懸浮顆粒，針對濁度去除率可達95％以上。且投入的氧化鐵顆粒可回收再利用於廢水處理系統中為磁種凝絮法的優點之一，因此本研究藉由加入不同濃度(0.1~2.0 CMC)及種類之界面活性劑(SDS及CTAB)回收再利用氧化鐵顆粒，以減少廢水處理成本及污泥產生量。研究中發現，若將氧化鐵以連續使用方式處理CMP廢水，1g 的Fe3O4可負載廢水中359 mg的總矽量。若加入低濃度（系統濃度0.1 CMC）之CTAB於處理系統中，可延長氧化鐵再用性。且針對廢水中濁度及總矽去除率均可達97 %以上，相當於1g 的Fe3O4可負載廢水中1917 mg的總矽量。若相較於利用氧化鐵單一次處理CMP廢水，其總矽增加率高達1497.5 %。若加入低濃度SDS，對於氧化鐵再用性僅有些微幫助，總矽增加率為400 %。實驗結果顯示，加入高濃度（系統濃度2 CMC）之SDS或CTAB回收再利用氧化鐵顆粒，其會增加氧化鐵與二氧化矽顆粒間之立體能障（steric repulsion），故氧化鐵顆粒處理廢水之成效即會大幅降低。 Magnetic seeding aggregation has been developed to remove silica nanoparticles from CMP wastewaters successfully with removal efficiency of turbidity higher than 95 %. With proper treatments, seeded magnetite (Fe3O4) nanoparticles can be reused repeatedly in the magnetic seeding aggregation of CMP wastewaters. In this study, the recovery of magnetite nanoparticles by different types and concentrations of surfactants and removal efficiency of total silicon (e.g. summation of silica nanoparticles and silicate) from CMP wastewaters treated by reused seeding particles were investigated. Experimental results showed that recovery of magnetite nanoparticles was always higher than 99% when silica/magnetite aggregates were treated by any SDS or CTAB concentrations used in this work (0.1 ~ 2 CMC). Though the addition of CTAB limited the separation between silica and magnetite nanoparticles, this improved the reusability of magnetite nanoparticles, which was due to lateral interactions of hydrophobic groups of CTAB molecules adsorbed on the surface of silica nanoparticles. When silica/magnetite aggregates were treated by 0.1 CMC CTAB, the silicon removal ability of magnetite nanoparticles is 1917 mg total Si / 1g magnetite, which is 1497.5% more than those used only once in the magnetic seeding aggregation of CMP wastewaters. However, total silicon removal efficiency of CMP wastewaters was very poor when they were treated by high concentration (2 CMC) of CTAB or SDS. This might be due to the steric repulsions between particles resulted from adsorbed surfactant molecules.