薄膜生物反應槽處理半導體廠廢異丙醇之探討

Abstract

目前半導體製程所排放之有機溶劑中，異丙醇(Isopropyl Alcohol, IPA)為最大宗之溶劑，其處理方式大多以收集後清運委外處理為主，而IPA具有生物可分解性，為了達到有機溶劑減量目標，本研究嘗試探討以廠內現有的薄膜生物反應槽(Membrane Bioreactor, MBR)生物處理系統進行處理。MBR是結合傳統活性污泥法與薄膜技術之廢水處理方法，廠區中MBR系統的污水來源為餐廳廢水、地排及化糞池之上層排出水，接著進入生物反應槽，再利用薄膜與生物處理去除水中的有機質，最後輸送至總放流或進入回收水系統。研究採用品管控制手法(Quality Control Story, QC Story)中的各項程序，例如系統數據收集整理，文獻的回顧與參考等，加以驗證後，以出流水的化學需氧量(Chemical Oxygen Demand, COD)和反應槽內的混合液懸浮固體物(Mixed Liquor Suspended Solids, MLSS)作為本研究探討的主要指標。 實驗期間依序每日嘗試添加10 L~100 L之IPA與原生活污水混合，當IPA添加至100 L時，出流水的COD開始有較顯著升高之變化，已超過出流水之標準，然而當IPA每日添加量固定為100 L時，觀察其COD變化，得知若將MLSS經適當排泥並維持於MBR系統中約20,000 mg/L，出流水的COD最低則可維持低於出流水標準。本研究是以實際工廠進行操作評估，證實薄膜生物反應槽處理有機溶劑具可行性，所獲得的參數指標可提供給業界參考。

Among the waste organic solvent drain from semiconductor manufacturing processes, isopropyl alcohol (IPA) accounts for the most significant amount of the waste solvent. The waste solvent is usually treated by collecting them and then sent to a qualitifed contractor for treatment. To achieve an objective of reduction of organic solvent, this study was attempted to explore the potential of using the existing membrane biological reactor (MBR) for the treatment of biodegradable IPA. MBR process combines traditional biological acivated sludge and membrane technologies for treating wastewater. The source of wastewater for theMBR system is from restaurants, floor drains and septic tanks and the treated water is either discharged or recycled. Research was conducted employing the Quality control story (QC Story) procedure, including steps such as data collection, review of literatures, and verification. Chemical Oxygen Demand (COD) and mixed liquor suspended solids (MLSS) were adopted as the main parameters in this study . During the experiment, 10 L to 100 L of IPA were in sequence added into the raw wastewater in collection tank. When 100 L of IPA was added, COD in the effluent exceeded the regulation level. However, if MLSS in the MBR system was reduced to around 20000 mg/L, the COD level in the effluent can be maintained under the regulation level. This study was conducted in the on-site MBR system in an semiconductor factory and demonstrated a possibility of using MBR system for treating IPA. Therefore, operation parameters obtained in this study may be as references for the industrial waste treatment.