| 摘要: | 混凝/膠凝程序一直是淨水處理過程中重要的單元，其操作的成效直接影響後續處理單元如沈澱與過濾單元的處理水質；混凝/膠凝為淨水工程中廣泛運用於去除水中微粒與有機物的物化程序。雖然國內外釵h研究對於混凝/膠凝的影響因子在實驗室之中皆有廣泛的探討，但於淨水場混凝/膠凝操作因子影響膠羽形成的實場評估卻是非常稀少。
本研究以實驗室所獲得的實驗數據為基礎，配合實際的操作現況，於現場進行混凝評估試驗。首先對潭頂淨水場現有設備及操作情況作一全面性的評估，以瞭解各單元操作的現況及對濁度去除的效能，再於實驗室利用淨水場現場不同水質之原水進行混凝劑最適劑量的評估，接下來再利用前述實驗評估所得的最適劑量針對混凝劑不同的稀釋比例、不同慢混攪拌操作（G、t值），以評估淨水混凝加藥稀釋與慢混操作對濁度去除之影響。
研究的結果顯示，若以現場操作的便利與穩定性而言，以沉澱掃除之作用機制為佳，拉長慢混時間可得到較佳的濁度去除成效。但隨Al(OH)3(s)的增加，會減少顆粒間的結合力，在混沉過程中容易破碎。這是因為在沉降過程中，由於大量的Al(OH)3(s)的產生，導致顆粒間的結合力下降所致；反之，若混凝作用為電性中和或異相混凝的機制，於沉降與再破壞之後，可能因膠羽破碎導致上層液中的懸浮顆粒增加，形成了後續殘餘濁度升高。南北兩區注入點的混凝劑鋁鹽型態會隨著輸送時間而變化，呈現不同比例鋁鹽成分組成，也導致不同最適加藥量的情況發生。
In water treatment, coagulation/flocculation is the most commonly used physicochemical process for particle removal, which is also an essential pretreatment for the subsequent sedimentation and filtration. Mechanisms of coagulation have been widely investigated by many researchers. However, the on-site studies of the impact of coagulation/flocculation performance on flocs were quite rare.
In this study, coagulation assessment experiments were carrying out in water treatment plant after the laboratory assessment test. In first step, a comprehensive assessment for the Tan-Din water facility was making for each unit operation in order to understand the current situation and the efficiency. And then, assessment tests for optimum coagulant dosage, coagulant dilution ratio, different mixing operations ( G, t value) were both carry out in Lab and on site.
The results showed that under the mechanism of Sweep-coagulation, it expressed higher stability for operation, therefore, the prolonged slow mixing can enhance turbidity remove. However, with the increase coagulation dosage, the floc size increased and showed loose structure. This is owing to the increase of Al(OH)3(s) and reduce the combination force between the particle and the other one. Under the other coagulation mechanism, the Charge-neutralization or hetercoagulation, and floc breakage would result in the residual turbidity increment because of the low floc recovery ability. In addition, two different dosing points, the north and south points in Tan-Din water treatment plant, showed different optimum dosage because of different deliver time, the injection coagulant showed different Ala, Alb and Alc proportion, it resulted different optimum dosage between the north and south treatment processes. |
