以生物法去除半導體產業與光電產業產生之水溶性有機廢氣研究(Ⅲ)

Abstract

本研究團隊過去參與「農業國家型科技計畫」，已成功研發出兩項成果：「可提高廢氣 處理效率之生物濾料製作法」、「以生物處理技術之廢氣處理系統及方法」。為解決工業廢 氣處理目前活性碳消耗量龐大及水洗塔循環水再生問題，我們結合高效能分解菌株（生物脫 附作用），加上水洗塔吸收效果（化學吸收作用），新開發以生物反應系統去除半導體與光 電產業排放之水溶性有機廢氣。 第一年計畫成果顯示，光電業排放的主要有機污染物以丙酮、異丙醇與乙醇為大宗。針 對半導體與光電業者所排放廢氣進行採樣分析，發現其中主要成份以丙酮為主，濃度範圍約 100 ppm，異丙酮次之(約20 ppm)，光電業另測得少量三氯乙烷( < 2 ppm)。我們將已篩選到 對水溶性有機物具高去除能力的菌株，在停留時間30 秒情況下，對100 ppm 之丙酮與異丙醇 氣體，具有99%以上的去除效果。進一步提高廢氣濃度，在停留時間10 秒鐘情況下，對800 ppm 丙酮去除率達95%，同時對800 ppm 異丙醇，可維持去除率達98%。在停留時間30 秒鐘，對750 ppm 乙酸丙二醇單甲基醚酯具有90% 去除率。在突變菌種篩選方面，共篩得 15 株菌株，以丙酮與乙酸丙二醇單甲基醚酯為基質測試，可耐受濃度為1500 ppm。 第二年計畫則針對目標污染物在各種不同操作條件下，進行生化反應速率及有機廢氣去 除效率之關聯性實驗，評估影響微生物去除率之因子。目前已完成實驗室生物濾床系統、流 體化生物洗滌塔及改良平板式生物洗滌塔在不同植種菌量與不同營養源條件下，對揮發性有 機污染物去除效率的探討。另外合作廠商清華科技檢驗公司也完成三座去除揮發性有機氣體 模場之建置及監測，結果顯示三組VOC 生物反應器的菌數皆可維持在108 cfu/g，偵測總碳氫 化合物之去除效果，其去除效率均達環保標準。目前合作廠商正進行建構其中一家半導體廠 放大二百倍後之實場生物反應器，預計將在今年七月完工進行測試運轉，因此今年度(第三年) 本計畫將對此實場反應器進行監測與採樣分析，針對進出流基質濃度、總碳氫化合物去除效 率、二氧化碳濃度、壓損及水中COD 濃度進行分析，同時也利用分子生物方法觀察菌相變化， 將監測分析結果與理論值比較，並根據實際操作條件進行參數係數修正，以提供實場改良參 考依據。最後將進行經濟分析反應器設置成本與操作成本，成為其他實場生物反應器開發建 置之示範場

The aim of this project is to establish the parameters of field-scale bioreactors which apply to the removal of water soluble organic waste gases emission from semiconductors and photonics industry. The trickling tower has been used to remove water soluble organic compounds. However, it needs a lot of water and produces waste water pollution. In the first year, we have screened 15 effective microorganisms which can efficiently remove several water soluble organic compounds. Moreover, we have developed and examined the efficiency of three types of reactors including biofilters, fluidized bioscrubbers and modified bio-plate towers to remove water soluble waste gases including acetone, IPA （isopropanol）, PGMEA（Propylene Glycol mono-methylether acetate）. The strains screened in our laboratory were immobilized in three types of reactors to analyze the removal efficiency during long-term operation. Steady-state efficiency (~99%) was carried out to remove 100 ppm acetone removal at the EBRT of 30s. When the EBRT reduced to 10s, the removal efficiency of acetone slightly decreased to 95 % at 800 ppm while the removal efficiency of isopropanol reached 98 % at 800 ppm. Also, at the EBRT of 30s, the removal efficiency of PGMEA was 90% at 750 ppm. In the second year, we studied and established the relationship between mass-transfer velocity, biochemical-reaction rate and removal of organic waste gases in different operation conditions. Also, some parameters has be set up and confirmed to modify a practical model for scale-up. In addition, a 100-fold scale-up biofilter will be constructed to eliminate organic waste gases by cooperative company. In the third year, the removal efficiency of waste gases, concentration of CO2, COD, pressure drop and pattern of bacteria in the scale-up biofilter will be monitored and compared with theoretical model. The related coefficients of operation parameters will be adjusted to improve the removal efficiency. Finally, we will analyze the construction cost and operation cost, which could be an important reference for additional scale-up in the future.