河川水加磁後水沙分離效應

Magnetic Separation of Sand from Water for River Water

梁昇(Sheng Liang) ； 劉志偉(Chih-Wei Liu)

《坡地防災學報》 8卷1期 (2009/05) Pp. 40-50

https://doi.org/10.29995/JSHR.200905.0004

摘要

農業灌溉用水，每因高濁度而受益。然而當灌溉用水轉移到其他部門，如民生或工業用時，高濁度卻是良好水質的致命傷。台灣典型用水大宗轉移的案例包括集集共同集水計畫的工業用水與石門水庫民生用水。二者均採用沉沙池處理後即引入供水渠道的原水，一旦逢遇雨期，水中泥沙卻如夢魘般地破壞使用者的期待。自然河川流水之含沙濃度均隨流量增大而增；降雨天氣時源源不絕的雨時逕流進水，除本身挾帶較高泥沙外，更不斷引起沉沙池已沉降沙粒的反彈與再捲揚，這數種作用下沉沙池內持的「澄清水」之濁度會在下雨時段反而持續維持偏高值。以集集共同集水計畫95年資料所呈現的包烙線足以說明這個論點。此包烙線隨水濁度增加而遞減其斜率，就是沉沙池濾沙功能潛力隨河水濁度的升高而遞減的關係。
在追求其他在槽的降低泥沙手段來代替沉沙池的軀動下，本文針對加磁法來促進水沙分離作用進行測試。本研究以加磁法來促進水（簇團）變小，因而減少流水挾持泥沙的能力而能產生泥沙快速沉澱作用。當磁力場4, 000高斯強度時，大安溪后里圳取水口自5,245NTU到132NTU與人工複製350NTU及720NTU樣品，經磁化後水沙分離效果提升，尤其第二次磁化後效果更加令人鼓舞。本研究因此認為二次磁化處理是灌溉用水移作他用時改良水質的可行選項。

關鍵字

磁化水沙分離 ； 人工複製濁水 ； 二次磁化 ； 灌溉水轉移

並列摘要

High turbidity in irrigation water benefits agricultural production but harms water quality if it is transferred to other sectoral uses such as industry or public purpose. Two typical large amount transfer cases happened in Taiwan are Chi-Chi common water collection system for industry use and Shi-Men reservoir for public use. Both relys on sediment basins after which water passes and drains by the supply ditch. Once happened it rains, sediment break the expectation of good water quality. By combing the following three reasons as firstly the sediment content in river water increases as increasing stream-flow, secondly of high sediment content in erosive runoff, and finally the bounce and re-suspension of the sediment trapped in the sediment basins, The enveloped line of paired data points shown in a figure represents sediment contents before and after sediment basin in 2006 at Chi-Chi common water collection system is sufficiently enough to give the self-explained reasons that the sediment content become extremely high in sediment basin during rainfall period. The slope decreases with increasing turbidity, that is to imply the filtering function potential of sediment basin decreased with increasing turbidity of water. Under the driving force to find out any replaced approach applied in channel, this paper performs separation effect of sand from magnetic water. Water groups from TaAn Chi River at the Intake of HoLi channel ranges turbidity from 5.245NTU to 132 NTU and from artificial river water samples in turbidities of 360 and 720NTU are magnetized. After double magnetized, separation effect is superior to once magnetized samples. Therefore, we recommend the double magnetized method.

並列關鍵字

Magnetic separation ； artificial river water ； double magnetized ； agricultural water transfer