矽晶圓之晶背研磨廢水處理及回收再利用評估

Abstract

本研究探討晶背研磨(Backside Grinder,BG)廢水之處理及廢水回收再利用評估。沉浸式超過濾(Ultrafiltration,UF)中空絲膜pilot系統用來處理個案工廠之BG廢水；於產水率提升過程中，pilot系統內的BG廢水污染物濃度亦同步升高，為瞭解BG廢水污染物濃度升高時，產水之水質的變化，應分析UF系統內的BG廢水水質及沉浸式超過濾膜產水之水質。研究結果顯示，個案工廠BG廢水之總固體物含量平均為1,000mg/L，其主要物質為矽微粒，且90%以上的矽粒徑小於1μm，另含少量之鈣、鎂、鐵等元素。以GE沉浸式超過濾膜(40nm)處理BG廢水後，其懸浮固體物SS去除率為99%以上，總固體物及矽、鈣、鎂、鐵等元素，平均去除率均亦達90%以上，故以沉浸式超過濾膜，去除矽微粒有良好的表現，但當pilot系統內的總固體物升高至15,000mg/L，超過濾膜產水之含矽量均容易超出50mg/L，不利個案工廠之再利用。在BG廢水處理過程中，不添加任何化學藥劑情況下，其pilot系統以膜通量於27LMH、每10分鐘反洗30秒及Air blow 15 L/min之操作條件下，可獲得穩定的570L/Day滲透產水量，且UF薄膜經長期運轉不易阻塞。BG廢水經沉浸式超過濾膜過濾後的水質極佳，優於生活次級用水及自來水供水標準。在不須增設任何水處理設備下，即可適用於冷卻水塔之水源補充及生活次級用水；但水源如欲導入廠區之純水系統，並供應產線生產使用，基於生產用水品質及風險考量，建議須搭配逆滲透膜處理後，再行導入純水系統。

This study investigates the wastewater treatment of backside grinder (BG) and the assessment of wastewater recycling using ultrafiltration (UF) hollow fiber membrane filter pilot system to deal with BG wastewater from the case factory. While the water production rate process was promoted, the wastewater pollutant concentration in the BG of the pilot system was also raised. To understand the changes in water quality while the wastewater pollutant concentration was increased in the BG, the water quality of BG wastewater in the UF system and that after filtering through UF hollow fiber membrane were analyzed. Analytical results indicated , the average total solid content of BG wastewater in the case factory was 1,000mg/L, which mainly contains silicon particles; 90% of these particles had a diameter less than 1µm a small amount of calcium, magnesium, iron, etc. were also found. After using the GE UF hollow fiber membrane (40nm) to filter BG wastewater, the removal efficiency of suspended solids (SS) was above 99% and the average removal efficiency of solids such as silicon, calcium, magnesium, and iron was above 90%. Thus, UF hollow fiber membrane demonstrated a good performance at removing the silicon particles. However, when the total solid in pilot system increased to 15,000mg/L, the silicon amount of wastewater after filtering through UF exceeded 50mg/L. This is no good for the case factory to reuse. In the BG wastewater treatment process, without adding any chemicals, when the pilot system operates under the membrane flux of 27LMH backwash for 30 sec every 10 min with Air blow 15 L/min, stable permeate water production could reach 570L/day, and UF membrane can have a long term operation without clogging. BG wastewater has great water quality after filtering through UF hollow fiber membrane, which is better than secondary living water and tap water. Therefore, the filtered water can be used as the supply for cooling water tower and as the secondary living water without any additional treatments. However, considering the water quality and risk of water production, it is recommended to use reverse osmosis membrane treatment to filter the water before importing into the pure water system to supply the production line.