本研究即針對此以廢酸液回收進行再利用研究，將其製作成多元氯化鐵(PFC)或多元硫酸鐵(PFS)的聚合鐵混凝劑與單體性氯化鐵(FeCl3)和實驗室所製備而成的高鐵酸鉀(K2FeO4)進行測試，當聚合鐵混凝劑在水溶液中會以存在大量的[Fe2(OH)3]3+ 、[Fe(H2O)6]3+ 、[Fe3(OH)3]6+ 等聚合鐵螯合離子呈現，具有多核螯合離子的立體聚合結構，是一種凝聚性能極佳的混凝劑，主要作用機制為電性中和與架橋作用；氯化鐵具有強烈的腐蝕性，在水中會消耗鹼度，其去除有機物質的最佳pH值在3.5 ~ 4.5之間，主要的去穩定機制為電性中和與沉澱網除；而高鐵酸鉀有先氧化後混凝的優勢，在溶液中會先以六價鐵(Fe6+)的方式存在於水中，先氧化溶液的有機質後再以(Fe3+)進行混凝的方式去除的優勢存在。
本研究將評估利用蝕刻廢水所製備之多元氯化鐵或多元硫酸鐵和氯化鐵與高鐵酸鉀的混凝去除濁度、色度、COD值和混凝完後之汙泥先以冷凍去水後使用傅利葉紅外線轉換(FT-IR)觀察汙泥中之官能基，介以推測是何種有機物質被混凝所去除。
先對實廠之水樣進行基本水質之分析，包含pH值、導電度、濁度、色度與COD值，然後以人工方式配製模擬實場之廢水作為本次研究使用，再利用聚合鐵混凝劑與氯化鐵和高鐵酸鉀透過瓶杯試驗針對pH值、藥劑劑量與攪拌條件(Gt值)等進行最適操作條件評估，瓶杯試驗的評估項目有殘餘濁度、色度與的評估，混凝後之溶液再使用UV分光測定COD值介以說明去除之效率。
本次實驗有助於多元氯化鐵或多元硫酸鐵和氯化鐵與高鐵酸鉀在實場中的高色度廢水中之去除與應用，可做為染整業減廢及提高混凝去除效率之參考。 This study investigated the efficiency of various iron-based coagulants, such as polymeric ferric chloride (PFC) and polymeric ferric sulfate (PFS) recycled from etching wastewater, simple ferric chloride (FeCl3) and laboratory-made potassium ferrate (K2FeO4). It has been widely known that the use of coagulants based on iron were effective in the removal of particles present in wastewater. In aqueous solution, polymeric iron exists as [Fe2(OH)3]3+, [Fe(H2O)6]3+ , [Fe3(OH)3]6+ with high molecular weight, thus, they are considered excellent coagulants due to their charge neutralization and bridging capacities. Meanwhile, K2FeO4 is a multifunction chemical that first acts as an oxidant and later as coagulant when Fe6+ reduced to Fe3+ without producing hazardous by-products.
In this work, dyeing and finishing wastewater was simulated and optimum operating parameters such as coagulant dosing, pH and mixing conditions (Gt value) were carefully studied. A series of jar tests were conducted to assess these iron-based coagulants in terms of turbidity and color removal. Moreover, to evaluate the organic matter removal efficiency, COD values were determined by UV/Vis Spectrophotometry. In addition, Fourier Transform Infrared (FTIR) Spectroscopy was performed to analyze the sludge formed after the coagulation and the functional groups observed in the sludge were used to specify the type of organic matter removed. Overall, this study demonstrates PFC, PFS, FeCl3 and K2FeO4 as promising chemicals for an enhanced wastewater treatment particularly in the dyeing and finishing industry.
