流導電流儀在混凝╱膠凝程序中自動加藥控制之研究

Abstract

台灣淨水場操作之自動化已進行多年，但對於混凝程序之加藥監控則尚缺 乏有效的方式。流導電流偵測技術乃藉連續量測水體微粒表面之電性，以 作為混凝之指標，提供淨水場混凝程序一個有效且經濟的加藥監控方式。 因此本研究利用實驗室中一連續式混凝╱膠凝模擬程序之操作，評估其可 行性及實用性。以往監測訊號收集不易，無法由充份的數據反應出連續監 控時之加藥動作，因此本研究在一連續訊號處理系統下進行試驗之數據記 錄。結果發現過去文獻對於流導電流偵測儀之缺乏認識，造成了濁度突增 時加藥動作時之之不當反應。故在本研究中對於流導電流讀值的理論進行 探討並加以修正，認為於低濁度之操作狀況下，流導電流感測壁面之原始 電性不能予以忽略。經修正後，使得流導電流之加藥監控對於濁度變化大 之淨水處理具可行性。且由實驗中的各項特性，得知此技術之應用上仍有 若干限制，並建議流導電流監控技術適用於淨水處理，而不適用於具高離 子強度之廢水處理，且加鋁量不宜過高。 A streaming current monitor (SCM) was used to goven the chemical dosage in the continued coagulation /flocculation process and evaluated its feasibility for the application in the automatic control of coagulation dose from many dosing responses about various conditions. This continued data-logging system offered the more sufficient data to the SCM responses at various conditions than before. The unreasonable dosing response was found at sudden increase on turbidity. It was due to the misunderstanding about the means of SCM reading in the previous studies. The effect of original charge on the SCM reading from the sensor surface would not be neglected ,especially at a lower turbidity condiction. The modified dosing model was developed and applied in this laboratory scale process. The results showed that SCM operation with modified control model was useful in the automatic control of coagulation dose with regards to various turbidity conditions. It was suggested that the application of SCM technique was limited to the raw water with low ion strength(i.e. Drinking water treatment) and to the operation with low alum dosage.