應用流體化結晶床處理含磷廢水之研究—以TFT-LCD廠為例

Removal of phosphorous wastewater by fluidized bed – a case study of a TFT-LCD plant

周連智(Lien-chih Chou)

指導教授 ： 秦靜如

國立中央大學/工學院/環境工程研究所/碩士(2012年)

摘要

本研究目的以實廠既有流體化結晶床（fluidized bed crystallizer，FBC）除氨氮系統改善為除磷系統，用在處理液晶顯示器（thin film transistor - liquid crystal display，TFT-LCD）含磷廢水的可行性研究，以期達到低磷排放之最佳處理效果。藉以提供未來TFT-LCD製造業含磷廢水，在除磷的最佳可行技術的應用參考。
本研究另探討，傳統化學沉澱與流體化結晶床在除磷的差異性。比較兩者在除磷效率的差異性，化學沉澱法除磷，在Ca/P莫耳比1.8、pH值8條件下除磷效率可達92 %；小型FBC模廠除磷試驗結果，Ca/P莫耳比1.6、pH值6.8條件下除磷效率可達95.2 %；在藥劑的加藥量對去除率的表現上，FBC模廠試驗結果較傳統化學除磷較佳。
實廠試驗的研究探討，分別使用氯化鎂、氯化鈣在除磷的結晶率與去除率的表現。實廠試驗結果證明，氯化鈣除磷較佳，在Ca/P莫耳比1.6，pH控制在6.8－7.2間，結晶率及去除率都可達70 %以上；預估每日約有3.5噸磷結晶物及磷鹽污泥產出，結晶產物構造主要以水合磷灰石（Ca5(PO4)3OH, HAP）與具有兩個結晶水的磷酸氫鈣（CaHPO4．2H2O, DCPD）複合之磷酸鈣產物，其純度高及易脫水特性，未來如能提供相關業者回收再利用，將可降低污泥處理問題。

關鍵字

結晶 ； 污泥減量 ； 鈣磷莫耳比

並列摘要

The purpose of this study was to investigate the removal of phosphorous wastewater from thin film transistor- liquid crystal display (TFT-LCD) by a full-sized fluidized bed crystallizer (FBC), which was originally designed to remove ammonia. The operation parameters, such Ca/P ratio, solution pH, and arrangement of tower (series or parallel) on the removal efficiency were examined in both pilot-scale and real-sized systems. From the pilot study, it was found that, compared to traditional chemical precipitation, the FBC had higher phosphorous removal efficiency with lower Ca/P. The phosphorous removal efficiency of FBC was 95.2 with Ca/P of 1.6, while that of chemical precipitation was 92 % with Ca/P of 1.8. The results of the pilot study were used in the real-sized fluidized bed. It was found that when the Ca/P was about 1.6, the solution pH ranged from 6.8 to 7.2, the crystallization efficiency of phosphorous calcium was up to 70 %. The major products were Ca5(PO4)3OH and CaHPO4．2H2O, with high purity and dewatering characteristics. It was also found that the chemical sludge produced in the fluidized bed was more suitable for sludge reduction and reused/recycled/reclamation.

並列關鍵字

sludge deduction ； Ca/P ； crystallization

參考文獻

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