應用鹼性固體廢棄物於生物滯留池強化磷酸鹽去除績效評估

Abstract

近年來，地表徑流已成為非點源污染的重要來源。磷（P）是一種備受關注的水污染物，因為它限制了大多數淡水系統的產量，若沒有合適的處理，大量磷進入水體可能導致富營養化，破壞周邊生態平衡。生物滯留是城市雨水管理中的一種低影響發展措施，其設計目的是減少洪峰流量、減少雨水量和減輕雨水污染物。生物滯留系統已經應用於去除污染物，如總懸浮固體和重金屬。 本研究主要目標在於選擇合適的鹼性固體廢棄物填充與生物滯留池的介質中並藉此提高磷去除效率。通過淋洗實驗和吸附實驗，對 6 種鹼性固體廢棄物進行了測試。結合這兩個試驗結果，選擇了八里垃圾焚燒廠的底灰（BA）用於替代生物滯留池中的 10%（按重量計）的土壤。通過掃描電鏡和 BET 分析，測定了BA 在洗滌前、洗滌後和吸附後的表面形貌和成分。 本研究建立了三種生物滯留池，分別為對照組、底灰組和飽和區生物滯留池。在生物滯留池中進行了批次試驗，以確定除磷效率。研究了降雨強度、磷濃度、植被和不同的生物保持池設計對其性能的影響。結果表明，改良生物滯留池具有良好的去除性能，且降雨強度較小，生物滯留池可以更徹底地去除磷酸鹽。在高磷酸鹽濃度下，磷酸鹽含量明顯下降。本研究所採用的植被對除磷效果不明顯。 此外，本研究測定了改良生物滯留體系除磷的吸附等溫線。結果顯示使用Freundlich 等溫線，可以更好地描述吸附過程。

Storm water runoff has become a significant source of non-point source pollution in recent years. Phosphorus (P), as a typical water pollutant, has raised great concern since it limits the productivity of most freshwater systems and may further cause eutrophication whenever high loads. Bioretention, a low impact development measure in urban storm water management, is designed to attenuate peak flows, reduce stormwater volume, and mitigate storm water contaminants. Currently, bioretention systems have been widely applied to water body pollutants removal, such as phosphorous, organics and other total suspended solids (TSS). This study focuses on the modification of bioretention media by certain alkaline solid wastes and thus to optimize the TP removal efficiency. The study compared six types of solid wastes on leaching and adsorption performance. Combining the results of these two experiments, bottom ash (BA) from Bali Refuse Incineration Plant was selected to replace ten percent (by mass) soil in bioretention soil. The characteristics of BA before leaching, after leaching and after adsorption were detected via SEM-EDS and BET analysis to obtain the surface topography and ash composition. Three bioretention cells were designed in this study which were control, bottom ash (BA) and saturated zone (SZ) bioretention cells. Batch experiments in bioretention cells were conducted to determine the phosphorus removal efficiency. The effect of rainfall intensity, phosphate concentration, vegetation and different bioretention cell designs on performance were investigated. The results suggest that the modified bioretention cell shows excellent removal performance and with smaller rainfall intensity bioretention cells could remove phosphate more completely. Under high phosphate concentration, the phosphate decreased noticeably. Vegetation used in this study doesn’t show remarkable improvement. The adsorption isotherms of phosphorus removal by the modified bioretention systems have also determined. The adsorption process could be better described by Freundlich isotherm.