| Abstract: | 都市垃圾焚化飛灰成份複雜且含有高濃度的重金屬、戴奧辛與氯鹽等問題，因此被歸類為有害廢棄物，資源化的難度高。本研究團隊發現水萃反應灰具有卜作嵐材料的特性，且水萃灰經研磨後的重金屬溶出濃度都相當低。但飛灰中大量的氯鹽即便經過水萃程序仍無法完全洗出，做為水泥摻配料會對水泥漿體的工程性質造成影響。因此本研究將淨水污泥摻合都市垃圾焚化飛灰來製成水泥取代料，並探討摻入水泥後的水泥漿體氯鹽穩定能力。
研究中將不同比例的煆燒淨水污泥與水萃灰混合，以不同濃度NaOH溶液、時間進行研磨活化，活化完之活化粉摻入水泥灌漿，進行7天及28天養護後檢測活化粉、水泥漿體的氯鹽再溶出量及氯鹽穩定能力，並搭配FTIR及XRD來觀察穩定氯鹽的機制。
由實驗結果得知，水萃灰中氯鹽含量高達160,000 mg/kg，當煆燒淨水污泥與水萃灰混合配比為70%比30%時，以水研磨活化96小時之活化粉，取代10%水泥量灌漿養護28天後，水泥漿體的氯鹽溶出量為N.D，氯鹽穩定率高達100%，相對抗壓強度亦提升至96.29%，無論在氯鹽穩定或抗壓強度都有相當好的成果。
The composition of municipal solid waste incinerator (MSWI) fly ash is complex, which contains high concentration of heavy metals, dioxins and chloride, was classified as hazardous waste and difficult to be recycled. From the former study, it was found that water-extracted MSWI fly ash (WFA) has the characteristic of pozzolanic property, and the heavy metals leaching potential of WFA are quite low after mechanical milling. Nevertheless, the large amount of chloride in the MSWI fly ash could not be lowed down effectively even after several times of water-extraction, that will impact the utility of the WFA recovery.
In this study, chloride stabilizing ability was explored by mechanical milling and alkali activation for the water treatment plant sludge (CWTPS) blended with WFA, in order to evaluate the feasibility of recovery the MSWI fly ash as cement substitute.
In this study, calcined CWTPS was blended with WFA in different weight ratios, milled and activated by different concentrations of NaOH solution compared with water for different periods to produce the activated powder, replaced a part of the cement, grouted and cured for 7 and 28 days, exam the chloride stabilizing ability of activated powder and the cement paste by FTIR and XRD analysis.
The results showed that, the chloride content of WFA as high as 160,000 mg / kg. When CWTPS blended with WFA in 70% to 30% by weight, milled with water for 96 hours, and then replaced 10% of cement, grouted and cured for 28 days, the chloride leaching concentration of cement paste was non-detectable. The chloride stabilizing rate reached 100%, and the relative compressive strength compared with pure cement reached 96.29%. Both the chloride stabilizing rate and compressive strength presented excellent results. |
