以鈣鹽去除工業廢水中的磷酸是常見的處理方法，促使磷酸根離子與鈣離子結合，並提高水中的pH值降低溶解度，藉由固態膠羽顆粒的形成，利用固液分離方式去除磷酸。本研究團隊目前已知膠羽影像色度分析技術( FICA )能即時監測膠羽顆粒的混凝行為，可利用RGB變化程度來判斷混凝效果和膠羽長成之依據，因此藉由FICA系統分析RGB值與膠羽變化情形之間關聯性，除了探討FICA系統監測化學沉降之可行性，並了解實驗參數的影響以及磷酸鈣化學沉降情況。研究結果顯示，RGB值隨著時間先上升後下降，最後呈平穩起伏，由在不同pH與Ca/P下RGB變化的差異可知，FICA監測系統能適時的反應出化學沉降中膠羽變化的情形，隨著初始pH值越高或是Ca/P比例增加，RGB變化趨勢明顯地提早。從RGB變化趨勢可知，當快混階段之上升斜率由大變小時，以及慢混階段之標準偏差(SD)越大時，所形成的膠羽越大；另外，B值和R值對白色顆粒變化反應較明顯，當顆粒越緊實時影像越亮白，因此B－R值越大，而且B－R跳動幅度越大則粒徑越大，表示磷酸去除率越好且化學沉降性佳。從膠羽顆粒狀態與RGB值之間各種相關的探討可知，FICA系統能應用於監測化學沉降，並能藉由RGB變化趨勢了解膠羽顆粒形成情況。Chemical precipitation is commonly used for the removal of phosphorous species from industrial wastewater. Floc image colorimetric analysis (FICA) has been developed to monitor coagulation process. The objective of this work is to explore the feasibility of FICA for the monitoring of chemical precipitation. Also, the influences of experimental parameters and the degrees of precipitation on RGB values were investigated. The results showed that the RGB values increased significantly and then decreased, followed by a steady undulation. It was shown that the changes of and the differences between RGB values were affected by the solution pH and Ca/P. At higher solution pH or Ca/pH, the turning points in the RGB patterns showed up earlier. Also, when the flocs became bigger, the rising slopes of RGB values decreased, the standard deviation (SD) became greater. Because the B and R values were more sensitive to the white images, which indicated that the compactness of flocs, it was found the B－R values and ranges were greater when the particles became more compact and bigger and the removal efficiency was also higher. This work concluded that FICA applied to monitor the chemical precipitation, and various analyses of RGB values were able to understand the growth of flocs.