多層複合濾料水質淨化系統(Multi-Soil-Layering System，MSL)為日本於 1990 年開發的現地處理設施，達至處理水質污染之效益。臺灣日前引進 MSL 技術已廣泛運用於許多地區，能針對各地區生活污水進行污染物等削減，進而保護排放至河川或水庫的水質。MSL 系統的使用年限在過去研究中較少討論，而污染物中正磷酸鹽的削減反應物會 存留於系統內，對於 MSL 系統之使用年限有較大關聯性，因此本論文針對系統中磷酸鹽的削減機制進行討論。本研究以不同材料填裝系統中的混合濾料包，探究標準配比(砂土:鐵粒:碳粒:稻殼 = 15:2:2:1)濾料包中的鐵粒與鐵粒以外其他材料對於磷酸鹽的去除百分比，並加入臺灣地區具有含鐵量較高的現地紅土置換濾料包中的砂土進行比較。 由實驗結果顯示，單個標準配比濾料包對於正磷酸鹽的削減率約為 21%，純鐵粒對於正磷酸鹽的削減率約為 16%，而鐵粒以外其他材料的削減率約為6%。而單個紅土配比濾料包對於正磷酸鹽的削減率約為 32%，顯示利用含鐵量高的紅土置換砂土有助於提升濾料包對於磷酸鹽的削減，並歸納出以削減率估算濾料包對於正磷酸鹽固定之削減總量，若以使用年限時提出以削減總量推估，需考量背景污染的濃度、目標削減率及現地處理的流量進行估算更完整。

Multi-Soil-Layering System (MSL) is a on-site treatment facility developed in Japan in 1990 for effectively addressing water quality pollution. Taiwan has recently introduced the MSL technology, which has been widely applied in various regions to reduce pollutants in domestic sewage, thereby safeguarding the water quality before its discharge into rivers or reservoirs. The lifespan of MSL systems has received limited attention in past research, and the retention of phosphate-reducing reactants within the system, especially the reduction of orthophosphate, is closely related to the system's longevity. Therefore, this paper focuses on discussing the mechanism of phosphate reduction within the MSL system. This study examines Soil Mixture Block (SMB) within different material-filled systems, investigating the removal percentage of phosphates by iron particles and other materials beside iron particles in the standard mix ratio (sand: iron particles: carbon particles: rice husks = 15:2:2:1) filter media pack. A comparison is made with the addition of locally abundant iron-rich red soil to replace sand in the SMB, in the context of the Taiwan region. Experimental results reveal that the removal percentage of orthophosphates is approximately 21% for a single standard SMB,around 16% for pure iron particles, and about 6% for other materials besides iron particles. In contrast, a single red soil ratio SMB achieves a removal percentage of about 32%, demonstrating that using iron-rich red soil instead of sand enhances the reduction of phosphates. The experiment also estimates the total reduction amount of orthophosphates fixed by the SMB, and proposes a method to estimate the lifespan by considering the total reduction amount, taking into account background pollution concentrations, target reduction rates, and on-site treatment flow rates for a more accurate estimation.

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