- 學位論文
廢白土與下水污泥共同堆肥化並再利用於土壤品質之改進
Using spent bleached clay co-composted with sewage sludge as organic amendment to improve soil quality
摘要
下水污泥富有極高含量之有機質、氮及磷等生物生長所需之養分，但因含有重金屬，而使得在土地施用上有其疑慮。廢白土可以吸附重金屬，與下水污泥結合後適合應用於土壤之改良。本研究即利用下水污泥及廢白土共同堆肥化處理，探討堆肥化過程之相關腐熟參數，並以序列抽出法監測堆肥化過程中廢白土對於下水污泥之重金屬型態轉變影響，另利用FT-IR觀察堆肥過程中之官能基轉變，再以腐熟堆肥依三種不同比利施用於土壤中，探討孵育過程之氮礦化量、CO2溢散量、磷、鉀含量及重金屬型態等變化，並結合盆栽試驗觀察堆肥施用後之土壤對於植體產量及肥力改善之成效。實驗結果顯示，依堆肥腐熟特徵可判別不同比例之下水污泥與廢白土混合製成之堆肥皆已達腐熟，而於堆肥過程中，重金屬可由不穩定之可交換態逐漸轉變為穩定之可氧化態或殘餘態。孵育試驗中，隨堆肥的施用比例不同而使得氮礦化速率及礦化潛能產生不同之結果，在重金屬型態變化部分，鉻、銅與鎳由較穩定型態略轉變為可交換態；鉛及鋅則不因土壤與堆肥混合孵育條件改變而有明顯變化。藉由小白菜盆栽試驗觀察，發現堆肥施用可有效提升植體產量，且盆栽試驗後土樣中之氮、鉀、有機質等養分皆因堆肥施用而有增加。
並列摘要
Sewage sludge is abundant in organic matter, nitrogen, phosphorus and other nutrients that can be used for crop growth. The nestriction of sewage sludge in land application is due to potentially contains heavy metals. Spent bleached clay due to its strong metal adsorption capacity can be used to fix heavy metals from sewage sludge, and to improve soil quality. This study was to use spent bleached clay co-composted with sewage sludge in the composting process. Key parameters in the process were determined by using composting mature and heavy metal fractionation. Fourier transfer infrared (FT-IR) spectroscopy was applied to evaluate the transformation of functional groups. Based on application of the compost with three rates into the studied soil, the measurements of nitrogen mineralization, CO2 emission, phosphorus, potassium and heavy metal transfer were conducted. A pot experiment was observed by Chinese cabbage and fertility amelioration of the soil was evaluated. The results showed that the acid-exchangeable fraction of heavy metals were gradually transformed to oxidizable fraction or residue fraction, respectively. With respect to the pot experiment, the compost application by three rates could create positive effects on the soil. Additionally, the sequential extraction of heavy metal indicated that the residue fractions of Cr, Cu, and Ni were changed into relatively unstable fraction, but Pb and Zn were constant among fractions during the incubation of soil and compost mixture. Comparison of the crop growth by the pot experiment, the compost application could increase the crop yield, and the contents of nitrogen, potassium and organic matter in the pot soil were significantly increased after the crop harvest.