| 摘要: | 隨著下水道普及率的提升，大量下水污泥的產生已使傳統處置方式不堪重負。因此研究從材料化的角度，探討將下水污泥摻入控制性低強度回填材料（CLSM）的可行性。且為提升下水污泥資源化再利用的效益，研究中引入焚化再生粒料進行相關試驗。本研究聚焦於三種不同乾燥程序處理的下水污泥：帶濾式脫水污泥、槳葉式乾燥污泥和熱泵式乾燥污泥，並特別關注脫水污泥。透過試驗了解污泥的材料特性及其在CLSM中的應用效果。利用摻料中的金屬離子與污泥中的不利因子進行化學沉澱，與水泥反應促進鈣釩石的生成，以解決下水污泥引起的嚴重緩凝問題。
本研究從工程效益、成本效益和減碳效益三方面進行綜合評估，並根據結果對下水污泥的處置提出建議。試驗結果顯示，將下水污泥應用於CLSM是可行的，但隨著污泥加入量越高，其試體強度越低且凝結時間變化劇烈，因此添加量有限並需搭配高水泥用量。硫酸鋁速凝劑適用於三種下水污泥，對下水污泥CLSM凝結時間有良好改善效果，且最佳使用量為水泥用量的10%至12%；過多硫酸鋁速凝劑的情況下，將影響強度發展。針對帶濾式脫水污泥，使用熟石灰作為摻料對下水污泥CLSM的強度具有明顯提升效果，過多熟石灰則會影響其凝結時間。下水污泥CLSM加入焚化再生粒料皆符合使用要求，但取代量不宜過多。
成本效益評估顯示，未來下水污泥產量將持續增加，污泥處置費用也有所上升，使得直接使用帶濾式脫水污泥能減少能源消耗和處理成本，具備經濟效益。於碳排放計算需以下水污泥全生命週期去進行計算，單考慮作為CLSM之原物料其碳排效益不佳，如若將下水污泥處理處置碳排加入計算其總碳排效益有所增加。且隨著掩埋場容量減少和運輸距離碳排放增加，材料化處置模式的環保優勢將逐年提升。
;With the increasing coverage rate of sewage systems, the substantial generation of sewage sludge has overwhelmed traditional disposal methods. Therefore, this study explores the feasibility of incorporating sewage sludge into Controlled Low-Strength Material (CLSM) from a materialization perspective. To enhance the benefits of recycling sewage sludge, incinerated recycled aggregates were introduced into the related experiments. This research focuses on three types of sewage sludge treated by different drying processes: belt-filter dewatered sludge, paddle dryer-dried sludge, and heat pump dryer-dried sludge, with a particular emphasis on dewatered sludge. The study examines the material properties of sludge and its application in CLSM through experiments. By utilizing the metal ions in the admixtures to chemically precipitate with the unfavorable factors in the sludge, a reaction with cement promotes the formation of ettringite to address the severe retardation issue caused by sewage sludge.
The study conducts a comprehensive evaluation from the perspectives of engineering benefits, cost benefits, and carbon reduction benefits, and provides recommendations for sewage sludge disposal based on the results. The experimental results indicate that applying sewage sludge in CLSM is feasible. However, as the amount of sludge increases, the strength of the specimens decreases, and the setting time changes significantly, thus limiting the amount of sludge that can be added and requiring a high cement content. Aluminum sulfate quick-setting agents are suitable for all three types of sewage sludge, significantly improving the setting time of sludge CLSM, with the optimal usage being 10% to 12% of the cement content. Excessive aluminum sulfate quick-setting agents can affect the strength development. For belt-filter dewatered sludge, using slaked lime as an admixture significantly enhances the strength of sewage sludge CLSM, but too much slaked lime can affect the setting time. The addition of incinerated recycled aggregates to sewage sludge CLSM meets usage requirements, but the substitution amount should not be excessive.
The cost-benefit evaluation shows that the future production of sewage sludge will continue to increase, and sludge disposal costs will rise, making the direct use of belt-filter dewatered sludge reduce energy consumption and treatment costs, thus providing economic benefits. Carbon emissions calculations should be based on the entire life cycle of sewage sludge. When only considering its use as a raw material for CLSM, the carbon reduction benefits are not significant. However, if the carbon emissions from sludge treatment and disposal are included, the overall carbon reduction benefits increase. Furthermore, with the decreasing capacity of landfills and the increasing carbon emissions from transportation distances, the environmental advantages of materialization disposal models will enhance annually. |
