| 摘要: | 隨著台灣地區污水下水道接管率提升，預期下水污泥產生量將逐年增加，因此污泥焚化已成為下水污泥處理方案之一。雖然污泥焚化有良好之減量及安定效果，但產生之下水污泥灰渣需加以資源化再利用，以減少最終處置需求及對環境衝擊。在各種下水污泥灰渣資源化技術中，將其回收作為骨材與卜作嵐摻料，並應用於水泥砂漿，經相關研究初步證明可行。然而對於下水污泥灰渣特性，及其在砂漿中之作用機制，以及污泥灰渣砂漿之改良技術，目前尚缺乏有系統之相關探討。 基於以上理由，本研究採取民生及八里污水處理廠下水污泥，以模具式焚化爐製備下水污泥灰渣，除分析其物理、化學、結晶及卜作嵐性質，並將樣本應用於水泥砂漿，取代部份骨材或水泥，並分析試體工作性及抗壓強度。至於在污泥灰渣砂漿改良技術方面，本研究選擇污泥灰渣高溫灼燒、機械研磨增加灰渣細度，以及於砂漿中使用強塑劑與活化劑等化學摻料，進行分析與探討。 本研究經試驗得知，下水污泥灰渣主要為污泥焚化之灼燒殘餘物構成，為表面不規則之細微顆粒，具有相當之孔隙體積與表面積，主要成分為矽、鋁、鐵之氧化物，以及石英等結晶成分，同時具有一定之卜作嵐活性。此外，本研究發現以下水污泥灰渣取代砂漿骨材，其灰渣砂漿工作性及抗壓強度發展均不理想；但以下水污泥灰渣作為卜作嵐摻料，以取代5?20%之砂漿水泥，則硬固試體第28天抗壓強度，可達控制組砂漿之60?80%，顯示具有應用價值。在污泥灰渣砂漿改良成效方面，本研究發現下水污泥灰渣經1,000?1,200oC高溫灼燒，並配合水淬處理，可明顯提高卜作嵐活性及灰渣砂漿工作性；以機械研磨處理下污泥灰渣，其細度每提高100 m2/kg，約可增加5%之強度活性指數；至於使用化學摻料，由於強塑劑之減水效應，以及活化劑對水化產物生成之催化作用，使其分別能改善砂漿工作性及早期抗壓強度發展。 綜合以上各項發現，本研究證明下水污泥灰渣具有特定之物理、化學及卜作嵐性質，可被視為一有用資源，並可應用於水泥砂漿以取代部份水泥。此外，本研究同時掌握污泥灰渣在砂漿中之影響機制，以及有效之灰渣砂漿改良技術，均有助於進一步提升其應用潛力與價值。 Due to the continuous upgrading of the service rate of the urban sewerage system in Taiwan area, the sewage sludge production is expected to increase simultaneously. Thus, the sludge incineration has become one of the alternatives for sewage sludge disposal. Although incineration can obtain optimum volume reduction and stabilization for sewage sludge, the sewage sludge ash (SSA) still needs to be reused in order to minimize the land demand for final disposal and the environmental impact. Among those reusing technologies, to apply SSA into cement mortar has been proved to be technically and economically feasible by previous research works. However, the total properties of SSA, and its roles in mortar, and the corresponding modification technologies for SSA mortars, have seldom been discussed in the literatures. For above reasons, this study selected the sewage sludge of the Ming-Shen Community WWTP and the Pa-Li WWTP to be investigated. The samples of sewage sludge were incinerated in a modular incinerator and the SSA was obtained. The physical properties, chemical compositions, crystalline constituents, and pozzolanic properties of SSA were analyzed. The SSA samples were further applied into mortar to replace partial cement or aggregate. Meanwhile, the workability and compressive strength of SSA mortar were tested. In addition, three potential modifications for SSA mortar, including the high-temperature calcination of SSA, the extended grinding to increase SSA fineness, the application of chemical admixtures, including super-plasticizers and activators, were also investigated and evaluated in this study. According to the test results, the SSA was essentially the burnt residue of raw sludge and contained fine particles with porous irregular morphology and great amounts of pore volume and surface area. The major chemical compositions of SSA included SiO2, Al2O3, and Fe2O3, and its crystalline constituent was primarily quartz. In addition, SSA exhibited certain pozzolanic activity. When SSA was reused to replace mortar aggregate, the SSA mortar exhibited poor workability and compressive strength. In contrast, when SSA was reused to replace 5-20% mortar cement, the compressive strength at age of 28 days of the hardened SSA mortar could achieve 60-80% of that of control mortar. This result revealed that to reuse SSA in replacing mortar cement has higher potential than in replacing mortar aggregate. Regarding the modification of SSA mortar, this study found that to calcined SSA at 1,000-1,200oC and followed by water quenching, could greatly improve the pozzolanic activity of SSA and the workability of SSA mortars. In addition, the extended grinding of SSA was found to increase 5% of the strength activity index of SSA with per increment of 100 m2/kg of the Blaine fineness. Finally, due to the water-reducing effect provided by the super-plasticizers, and the hydration acceleration effect provided by the activators, to apply the chemical admixtures could improve the workability and compressive strength development at early ages of SSA mortars respectively. Based on above results, the SSA is a useful material in respect of its physical, chemical, and mineral properties, and can be reused as a pozzolanic material to replace partial cement of mortar. This study has also revealed the roles and mechanisms of SSA, and the effective modification technologies for SSA mortars. These findings are helpful in elevating the potential and value of the application of SSA in cement mortar. |
