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An Investigation of Spiral Flocculation and Direct Filtration System
optimum operating conditions
average floc size
|上傳時間: ||2009-10-08 14:53:19 (UTC+8)|
|摘要: ||為增進混凝成效，本研究之螺旋混凝設備係以細、粗不同內徑之半透明塑膠管纏繞在直徑PVC管柱上分別作為混凝單元之快混與慢混設備。實驗中藉由水流通過螺旋管中，因水流斷面間之速度差而產生混合之效應達成混凝之效果。在研究之過程中，以高嶺土分別配置成濁度為15.9、55及100NTU三種不同濃度之懸浮液，並分別以硫酸鋁、多元氯化鋁及氯化鐵為混凝劑。由實驗結果得知：以硫酸鋁與氯化鐵為混凝劑時所形成膠羽之尺寸大小與沉降性並不一致，但以PAC為混凝劑時則趨於一致。另外，分別以硫酸鋁、多元氯化鋁及氯化鐵為混凝劑時，當高嶺土懸浮液濁度為55 NTU時，所形成膠羽之平均粒徑均較懸浮液濁度為15.9及100NTU時為大。最後並比較瓶杯機械攪拌與螺旋管混凝之成效得知兩種混凝方式，雖然瓶杯機械攪拌沉降後之上澄液水質較佳，但若以混凝設備之效率而言，連續水流(in line)之螺旋混凝設備之效率比批式(batch)瓶杯機械攪拌之混凝設備高。
For improving the efficiency of flocculation, two plastic tubes with different internal diameter wounded on the surface of a PVC column were used as a spiral flocculator in this study. The spiral flocculator functions on the principle of flow through spiral tube created a velocity gradient and flocculated the flow. Three different turbidities of Kaolin Clay suspensions of 15.9, 55 and 100NTU, and three coagulants of aluminum sulfate (Alum), ferrous chloride and polyaluminum chloride (PAC) were used in this study. It was found that there is inharmonic between the average floc size and sedimentation property by using aluminum sulfate and ferrous chloride as coagulant, but it is harmonic by using PAC as coagulant. It was also found that the biggest average floc size was obtained at the turbidity equal to 55 NTU of Kaolin Clay suspensions. Moreover, although the better supernatant could be acquired by the mechanical mixer with batch type, but the higher flocculation efficiency was happened at inline spiral flocculator
In other hand, a direct filtration system using deep bed filter was also investigated in this study. The pilot filter has 30cm of length and 5 cm of diameter. Experiments were conducted under various operating conditions including influence, characteristics of media (sand and anthracite), packed depth and filtration velocity, in order to observe the relationships between the filtration head loss and the filtrate quality, and the optimum packed depths of the filter were also obtained. From the experiments results, it was found that the higher filtration head losses and the better quality of filtrate were happened when an influence flocculated by ferrous chloride, sand used as packed material and packed depth was thicker. In addition, the filtration velocity increased with an increase in filtration head losses, but with a decrease in filtration run. Finally, the optimum packed depths of a filter under the various operating conditions were also found in this study.
|Appears in Collections:||[環境工程與科學系(所)] 博碩士論文|
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