CMP(化學機械研磨)是半導體製造業的重要工藝。製程中所使用研磨液及後清洗液均會導致CMP研磨廢水濁度提高。CMP研磨顆粒屬奈米等級且具有較高介達電位，一般混凝沉澱效能不佳，因此著手研究二氧化矽與 氧化鋁廢水混合處理之特性與作用機制。 本研究以二氧化矽研磨液及氧化鋁研磨液稀釋200倍來模擬實廠排放廢水 透過不同混和比例：100%二氧化矽、70%二氧化矽+30%氧化鋁及50%二氧化矽+50%氧化鋁確認對混凝效果之影響。由實驗結果發現當廢水pH 為7時殘餘濁度最低，殘餘濁度隨著pH上升而增加。另外當廢水pH為7且PACl添加量為600ppm時，殘餘濁度會隨著氧化鋁濃度增加而增加，原因為氧化鋁研磨液本身濁度較高。 另外針對陽離子和陰離子助凝劑不同混合比例對於去除濁度、總懸浮固體、化學需氧量和粒徑分析的影響進行研究。由實驗結果發現陽離子和陰離子助凝劑加藥量絕大部分取決於二氧化矽與氧化鋁混合比例。當氧化鋁混合比例上升時，總懸浮固體較高，原因為氧化鋁顆粒粒徑大於玻璃纖維濾紙孔徑0.1μm及氧化鋁密度高於二氧化矽。 通常混合研磨廢水中含有較高濃度氧化鋁時會得到較高殘餘濁度，儘管二氧化矽與氧化鋁三種混合比例的去除效率相似。建議當廢水中存在兩種不同的CMP研磨顆粒時，70%二氧化矽+30% 氧化鋁可得到更好的混凝效果。;CMP(chemical mechanical polishing) is an important process in semiconductor industry. Both of polishing slurry and post cleaning result in high turbidity of CMP wastewater. CMP particles are in nano scale and have high zeta potentials, which are difficult to remove by coagulation and flocculation. In this study, chemical coagulation treatment of mixing silica and alumina oxide CMP wastewater was studied. The wastewater was prepared by diluting silica and aluminum oxide (Al2O3) slurries to 200 times. Effects of mixing ratio on coagulation were examined by 100% silica, 70% silica and 30% Al2O3, and 50% silica and 50% Al2O3. It was found that the residual turbidity was the lowest when the solution pH was 7 and increased with increasing pH. Also, when the solution pH was 7 and PACl was 600 ppm, the residual turbidity increasing with increasing amount of Al2O3, which is because the Al2O3 slurry had much higher turbidity. Effects of the mixing ratio of cationic and anionic polymers on the removal of turbidity, suspended solids (TSS), chemical oxygen demands (COD),and particle size distribution were also investigated. It was found that the dosing of cationic and anionic polymer was greatly dependent on the ratio of silica and Al2O3. The TSS was higher when there were more Al2O3 nanoparticles, which was because the particle size of Al2O3 was larger than the pore size of the filter (0.1 m) and the density of Al2O3 was higher than that of silica. In general, higher ratio of Al2O3 leaded to higher residual turbidity though the removal efficiencies for three mixing ratio of silica and Al2O3 were similar. It is suggested that when there are two different CMP nanoparticles in wastewater, 70% silica and 30% Al2O3 would have better coagulation performance.
