請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64680
標題: | 下水污泥碳化之生命週期評估 Life cycle assessment of sewage sludge carbonization |
作者: | Ning-Yi Wang 王寧沂 |
指導教授: | 闕蓓德(Pei-Te Chiueh) |
關鍵字: | 下水污泥,碳化,生命週期評估,共燃,生質能, Sewage sludge,carbonization,life cycle assessment,co-firing,bioenergy, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 台灣地區近年來都市發展快速,政府大力推廣興建污水下水道,預期民國103年提升全國公共污水下水道普及率至35.77%,屆時每天污泥產量將達到約1040公噸。污泥的成分複雜,須以適當方式處置,傳統處理方式如掩埋可能面臨土地資源缺乏問題,而焚化亦面臨二次污染控制問題。隨著再生能源議題受到關注,可將污泥轉化為生質能源的碳化技術亦已有文獻發表。污泥碳化(carbonization)可將下水污泥製成生質炭(biocoal),擁有體積減量、有效利用污泥熱質、增加可磨性、除臭、抑制N2O排放、容易保存等優點。污泥的生質炭應用於發電廠共燃(co-firing)發電,不僅減少化石燃料的消耗,亦可減少溫室氣體的排放,在日本、美國亦有少數實際案例。然而碳化各階段有能源與物質的投入產出,此種進出皆可能造成環境影響,本研究利用生命週期評估軟體 SimaPro 7.2,並選用其中的 IMPACT2002+衝擊評估模式,進行污泥碳化之環境效益與衝擊評估,並以掩埋、化(混燒)及單獨焚化方案為比較基準。本研究之功能單位為1公噸都市下水污泥,由於生質炭取代部分煤炭共燃發電,結果顯示污泥碳化方案於陸域生態毒性(Terrestrial ecotoxicity)、水域生態毒性(Aquatic ecotoxicity)、土地利用(Land occupation)、游離輻射(Ionizing radiation)、水體優養化(Aquatic eutrophication)、非再生資源(Non-renewable energy)、礦物資源(Mineral extraction)衝擊類別,具有減量的正面效益。綜合評估結果顯示四種下水污泥處置方案,四種污泥處置方案中,以污泥生質炭共燃案例為最佳方法,其次依序為混燒、掩埋及單獨焚化方式。至於溫室氣體排放的結果,掩埋排放量最高 296.9kg CO2eq,其次為單獨焚化 232.2kg CO2eq、生質炭共燃 146.1kg CO2eq 及混燒-15.4kg CO2eq。雖然綜合評估結果中,生質炭共燃案例為最佳方法,但考慮非再生能源消耗及節能減碳之議題,碳化製程若能改善因污泥高含水率所導致的能源消耗,使製程的能源利用效率提升,下水污泥碳化技術將能有效減少溫室氣體排放等衝擊影響。因此,決策者須權衡下水污泥處理之環境衝擊,以評估生質能源於環境面之可行性。 Sewage sludge production in Taiwan is rapidly increasing as a result of continuous population growth. Wastewater treatment plants are estimated to generate 1040 ton/d of dewatered sludge by 2014. Therefore, evaluating currently available dewatered sludge management practices is critical for reducing the negative impacts of sludge management and disposal. Currently, landfill and co-incineration with municipal solid waste are the 2 most common approaches for managing dewatered sludge from wastewater treatment plants in Taiwan. However, the scarcity of available land for landfill and the prevention of secondary pollution as a result of incineration are pressing problems without a satisfactory solution at this moment. One recently proposed method that is increasingly receiving the attention of researchers is carbonization, because it not only recycles sewage sludge but also reduces greenhouse gas emissions. Carbonization is a newly developed process that converts sewage sludge to biocoal which is a type of solid biomass that can be used to partially substitute coal for power generation. Carbonization offers the advantages of reducing sludge volume, exploiting its thermal content, increasing sludge grindability, removing odor, reducing N2O emission and easy handling. However, during the carbonization process, the input and output of energy and materials may create some adverse environmental impacts. Therefore, the main objectives of this study were to compare and evaluate the application of carbonization, landfill, co-incineration and mono-incineration processes for sewage sludge treatment in Taiwan regarding various environmental impacts. The life cycle assessment software SimaPro 7.2 was used and the IMPACT2002+ methodology was applied to evaluate functional unit of 1 ton municipal sewage sludge. Noticeable positive results regarding terrestrial ecotoxicity, aquatic ecotoxicity, land occupation, ionizing radiation, aquatic eutrophication, non-renewable energy and mineral extraction were observed when co-firing of biocoal and coal was applied for power generation. Overall, carbonization is the optimal treatment approach followed by co-incineration, landfill and mono-incineration. Although carbonization is the ideal solution for sludge treatment, even after sludge pre-treatment (condensation, digestion and dewatering), the sludge still contains high content of moisture, thus requiring a significant amount of energy consumption. Therefore, carbonization of sewage sludge could be more effective once the energy delivery efficiency is enhanced. Moreover, it is imperative for policy makers to consider environmental impacts and evaluate the environmental feasibility of bioenergy recovery. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64680 |
全文授權: | 有償授權 |
顯示於系所單位: | 環境工程學研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-101-1.pdf 目前未授權公開取用 | 3.58 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。