生物炭及水力停留時間對土壤管柱系統溫室氣體排放及甲烷菌群變動之影響

Abstract

氣候變化與人類活動加劇了溫室氣體 (Greenhouses gases, GHGs) 的排放，如甲烷(Methane, CH4)及二氧化碳(Carbon dioxide, CO2)。GHGs的上升增強了溫室效應，對生態環境、農業以及人類健康造成嚴重影響。本研究透過土壤管柱系統模擬廢水生態土壤滲濾系統(Wastewater ecological soil infiltration system, WESIS)，添加生物炭以及調整不同空床接觸時間 (Empty Bed Contact Time, EBCT)，以減少CH4與CO2排放為本研究重點。生物炭是近年來被國際認可的減排技術，具有高比表面積、孔隙度以及豐富的官能基，能有效改善土壤性質。所以透過批次實驗結果得知，添加10%生物炭的組別在Gompertz模型擬合中顯著降低了CH4及CO2的排放速度。將10% 生物炭應用於土壤管柱系統，其結果顯示，10%生物炭的組別在EBCT 4天時，有最低的有機負荷為2.08 g/m³/h ，明顯降低了CH4和CO2的排放通量，分別為1.216 mg/m²·h·kg soil以及5.94 mg/m²·h·kg soil，較未添加生物炭系統降低了30.1%以及2.78%的排放量，且COD和TN去除率分別為89.28%和21.97%，比未添加生物炭的系統提升了6.58%和40.9%去除率。在微生物群落方面，添加生物炭的系統中，隨著mcrA、pmoA基因增加，CH4以及CO2呈下降趨勢。且發現添加生物炭能增加下層土壤pmoA基因與甲烷氧化菌16S rRNA基因數及相對豐度。根據本研究結果可得知，添加10%生物炭且以EBCT為4天的WESIS操作條件，在減少溫室氣體排放和提升污染物處理方面具有顯著潛力，對優化WESIS和其應用具有重要參考價值。

Climate change and human activities have intensified the emission of greenhouse gases (GHGs), including methane (CH₄) and carbon dioxide (CO₂). The rising levels of GHGs have amplified the greenhouse effect, leading to profound impacts on ecological systems, agriculture, and human health. This study aims to mitigate CH₄ and CO₂ emissions by simulating a wastewater ecological soil infiltration system (WESIS) through soil column experiments, incorporating biochar, and adjusting various empty bed contact time (EBCT). Biochar, recognized internationally in recent years as an effective emission reduction technology, possesses a high specific surface area, porosity, and abundant functional groups, thereby enhancing soil properties. The results of batch experiments indicated that the group with 10% biochar significantly reduced CH₄ and CO₂ emission rates, as demonstrated by the Gompertz model fitting. When applying 10% biochar to the soil column system, the results showed that at an EBCT of 4 days, with the lowest organic loading of 2.08 g/m³/h, CH₄ and CO₂ emission fluxes were markedly reduced to 1.216 mg/m²·h·kg soil and 5.94 mg/m²·h·kg soil, respectively, representing reductions of 30.1% and 2.78% compared to the system without biochar. Furthermore, COD and TN removal efficiencies were 89.28% and 21.97%, respectively, showing increases of 6.58% and 40.9% over the system without biochar. Regarding the microbial community, the system with biochar addition exhibited a decrease in CH₄ and CO₂ emissions concurrent with the increase of mcrA and pmoA genes. Additionally, the introduction of biochar was found to enhance the abundance and relative abundance of pmoA genes and methane-oxidizing bacteria 16S rRNA genes in the lower soil layers. The findings of this study suggest that the application of 10% biochar with an EBCT of 4 days in WESIS demonstrates significant potential for reducing greenhouse gas emissions and improving pollutant removal, providing critical insights for the optimization and application of WESIS.