「多層複合濾料水質淨化系統 (Multi-Soil-Layering system, MSL)」(以下簡稱為MSL)為日本於1990年開發之現地水質淨化技術，臺灣與日本建立跨國合作關係，並自2015年引進MSL技術之後，嘗試將材料及施工方法本土化，並且已成功應用於國內許多地區。MSL是一種現地自然淨化系統 (On-site Natural Treatment System, NTS)，可廣泛應用於處理家庭生活污水及畜牧排放廢水等點源污染，亦可以使用於淨化河川、埤塘或水庫等之污染。近年來由於國內有愈來愈多的實務案例正在執行，但相關的本土化施工規範仍付之闕如，本研究主要針對目前國內採用的材料及施工慣例來研訂合宜的施工規範供參考。MSL內部組成主要分為兩大部分，「混合濾料層 (Soil Mixture Layer, SML)」以及「滲透濾層 (Permeable Layer, PL)」。經實驗結果得知，SML之最佳滲透係數(k值)控制於1.0 × 10-3 ~ 9.9 × 10-3 cm/sec可得到最佳的污染去除效率，且PL之k值控制於1.0 × 10-1 ~ 9.9 × 10-1 cm/sec可有效避免系統堵塞；再者，SML內之砂質土壤若可以採用火成岩風化土壤，可以提高部份的磷吸附能力，但目前臺灣僅有離島土壤具有上等功效，本島仍建議採用砂土。除此之外，SML施工時的夯實度亦須控制大於85%的最大乾單位重，一來可有效控制施工的夯實品質，二來可提供足夠的承載力來支撐上部荷載，避免日後沉陷的發生，由於現地進行夯實度檢測不易，故建議可以採用山中式土壤硬度計來替代，便可即時檢測現地SML的夯實密度。

"Multi-Soil-Layering System (MSL)", developed by Japan in 1990, is an on-site water purification technology. Taiwan and Japan have established a cross-border partnerships. Since the introduction of MSL technology in 2015, we have tried to localize the materials and construction methods used, and we have successfully applied them in many areas of our country. MSL is an On-site Natural Treatment System (NTS), which can be widely used to treat point source pollution such as household sewage and livestock wastewater. It can also be used to purify pollution in rivers, ponds or reservoirs.
In recent years, as more and more practical engineering cases are being implemented in our country, the relevant localized construction specifications are still lacking. This research mainly focuses on the materials used in our country and past construction practices, and develops appropriate construction specifications to provide reference.
The internal composition of MSL is mainly divided into two parts, "Soil Mixture Layer (SML)" and "Permeable Layer (PL)". According to the experimental results, the best permeability coefficient (k value) of SML should be controlled within (1.0~9.9) × 10-3 cm/sec to obtain the best pollution removal efficiency. And controlling the k value of PL within (1.0~9.9) ×10-1 cm/sec can effectively prevent the system from clogging. Furthermore, if soil formed by weathering of igneous rock can be used in SML, the ability to absorb phosphorus can be improved. However, only some soils on offshore islands in our country have superior effects, and it is still recommended to use sandy soil in Taiwan.
In addition, the compaction degree during constructing SML must also be controlled to be greater than 85% of the maximum dry unit weight. As a result, the compaction quality of construction can be effectively controlled. Secondly, it can provide enough bearing capacity to support the upper load and avoid the occurrence of subsidence in the future. Since it is not easy to check the compaction degree on site, it is recommended to use a soil hardness tester (Yamanaka type) instead, which can immediately detect the compaction density of SML.

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