光纖技術監測淨水膠凝行為之研究

Abstract

水處理單元中混凝程序的加藥控制一直是水處理自動化的瓶頸,但尚缺乏 有效的監控方法對混凝膠凝行為作即時監測。光纖偵測技術為使用光學的 方式,利用量測穿透懸浮液的光強度變動情形作為膠羽生成大小的指標,並 可依其作為現場混凝監控及決定混凝最適加藥量之方法。本研究利用批次 實驗探討PDA(Photometric Dispersion Analyzer)在各種情形下的操作, 評估用於實場監控膠凝的可行性及實用性。由結果顯示監測的過程中,PDA 可以靈敏地偵測出不同混凝劑量對膠羽生成之效的最大值表示生成沉降性 最良好之膠羽,可用其作為決定最適加藥量之依據。PDA適合不同混凝劑之 監測,能即時得到膠凝所生成膠羽大小特性之資料。此外在不同的濁度情 況之下,尤其是濁度,亦能正常操作,顯示其能適應濁度突然變化的情況,而 且能正確地指出最適藥量,因此很適合作為現場監測膠凝及決定混凝加藥 量的技術。另外,原水本身的特性,如離子強度,色度,及pH等,並沒有對PDA 的監測造成困擾,反而能靈敏地監測這些因子對膠羽生成大小之影響,使得 光纖偵測技術的適用範圍不限於淨水膠凝之監測。由本研究所獲致之結果 顯示在即時監測膠凝的技術上,光纖技術為一極具潛力之監控工具。 On-line monitoring the state of coagulation/flocculation enables automatic control of coagulation process with respect to the condition of the chemical additive. A new method "Fiber- optic monitoring thehnique" as a tool has been employed to evaluate the state of flocculation, which is to measure the flutuating light intensity transmitted through a flowing suspension. The purpose of this study is to assess the feasibility for the application of monitoring the flocculation by using photometric dispersion analyzer (PDA), and to perform a series of batch flocculation tests with PDA under different conditions. The result shows that the fiber-optic technique is useful to monitor the state of aggregation with different coagulants and the variation of turbidity conditions, it provides a reliable index related to the floc size can be used in determing the optimum coagulant dosage. Nevertheless, it also can be used in the case of wastewater treatment. The result concludes that PDA is superior to streaming current detector in monitoring the state of flocculation.