廢棄物焚化灰渣最適當處理研究

台灣地區近年來，由於經濟快速成長，人民生活水準大幅提高，因而廢棄物產出量亦隨之大量增加，加上外貿與工業生產高度成長，造成產業廢棄物之增加，甚而下水污泥亦待處理，因此廢棄物處理工作，已成為不能輕忽的重要課題。據統計垃圾清運量已從民國79年的625萬公噸/年，提升到民國85年的880萬公噸/年，預估民國89年更將高達1070萬公噸/年，若加上事業廢棄物其數量更是驚人，資料顯示85年台灣地區的事業廢棄物高達3000萬公噸/年。廢棄物處理可分為掩埋、焚化、回收三大方式，台灣地區地狹人稠，土地資源有限，掩埋處理非長久之計，且廢棄物中有機物與有害物質，也會造成環境污染。焚化處理可防病菌傳染，使有害物質無害化，更可在短時間內減容為原來的10﹪~15﹪，故成為廢棄物處理的主流。回收雖漸受重視，但數量有限。基於上述，民國72年行政院第五次科技顧問會議確定「焚化是台灣地區最可行之長期垃圾處理方法。」，民國79年政府於垃圾處理基本政策中更揭示：配合都會區發展，未來垃圾處理應以焚化為主，在考慮經濟規模及能源利用的前提下以設置中、大型垃圾焚化廠為原則。政府以致力於設立焚化廠來解決垃圾問題，預定民國89年以前完成22座垃圾焚化廠，每天可處理22,050公噸的垃圾，約佔89年垃圾量之75﹪。垃圾焚化後殘留10﹪~15﹪的灰渣，若無適當的處理將會產生二次污染及掩埋場地難覓等問題。由於科技的進步現今對於二次公害中的飛灰、氯化氫、硫氰化物、氮氧化物等均可做到高破壞去除率的技術水準。目前的課題則是如何將含有重金屬及戴奧辛等之灰渣，予以減量及無害處理。本研究以台北縣樹林及台北市木柵垃圾焚化廠分別代表乾式及濕式系統，探討焚化灰渣基本特性，分析項目包括灰渣含水率、灼燒減量、原灰ph值、重金屬總重濃度及毒性特性溶出程序(TCLP)之重金屬濃度。本文主要目標在探討都市垃圾焚化灰渣重金屬物種形成、分佈特性、建立本土化資料，提供未來焚化灰渣再資源化之參考。結果顯示鉛主要分佈於底灰與及集塵灰中；鎘分佈於集塵灰及反應灰中；鉻平均分佈在灰底、鍋爐灰與及集塵灰中；鋅分佈在反應灰及底灰中；汞主要分佈於集塵灰與反應灰中。根據國內底灰與飛灰重金屬含量分析及和國外情況比較加以研究國外灰渣處理及資源化技術綜合研討，建議日後國內焚化廠加裝分類設施有助於降低焚化灰渣中重金屬之含量。而底灰中鎘汞之含量不高，未來可直接作為製磚或造路之原料，至於飛灰在處置前以萃取法回收主要重金屬應是兼顧避免兩次污染及回收資源之必要步驟。

關鍵字

灰渣

並列摘要

The Municipal waste was increased quickly due to sharp improvement of prosperous economy and people living in Taiwan. The industrial wastes were also increased because the gradual growth of export and domestic requirement to local industries. Thus, the disposal of refuse has become vital topic today. The scavenged quantity of municipal waste was increased from 6.25 million ton/year to 8.8 million ton/year between 1990 and 1996.The predicted quantity will be much as 10.7 million ton/year in the coming year 2000.As for the industrial waste, the quantity was more than 30 million ton/year by the report in 1996. Landfill, incineration and recovery are three essential methods of waste disposal. Landfill will not be accepted due to lack of proper location for high population density in Taiwan. The characteristics of 85%~90% volume reduction and almost-complete harmful-constituent destruction in short time make incineration be disposal method. The recovery will be paid more attention in the next stage. Based on the above reason, "incineration will be most feasible municipal waste disposal method for the long-term scheme in Taiwan was determined at the fifth technology consultation committee of Excutive Yuan in 1983.Furthermore, the main policy of the municipal waste disposal was announced by the government in 1989, that incineration will be main method of the municipal waste disposal and the medium or large incineration plants will be constructed according to urban development, beneficial capacity & recovered energy utilization in the future. Concretely, the 22 incineration plants were scheduled to be set up around this island by the year of 2000.The treatment rate will be 22 thousand ton/year that is almost 75% of daily municipal-wast production-rate in the year of 2000. Although the wide-application of incineration technique can deal with refuse disposal problem effectively, to avoid second pollution after incineration becomes new focus. As we know, most of the second-pollution causing contents, for example, particulate, HCl, SOx & NOx can be destroyerd or gotten rid of by wide-commercialized techniques. Unfortunately, the reduction and treatment of harmful contents in left ash (10%~15% of original volume) especially for heavy metal and dioxin are still important issues in the present. The purposes of this study is to study the constituents, distribution of heavy metal in ash of present incineration plants in Taiwan, in addition, the treatment techniques in the world are collected for future-application suggestions after overall analyses and discussions. The moisture content, burned reduction rate & PH value of the collected ash in addition to total mass fraction(mg/kg)by elemental analysis & liquated mass contration (μg/l) by the analysis of toxic characteristics after liquefaction precesses for heavy metal in the ash are investigated. The representative test samples were collected from Mu-Zha incineration plant in Taipei city for wet-type of APCZD & Shu-lin incineration plant in Taipei county for dry-type of APCD (air pollution control device). The results reveal that pb in bottom ash below particulate-collector, Cd in reaction ash & ash below particulate-collector, Cr in bottom ash & ashes below both boiler & particulate-collector, Zn in botton ash & reaction ash in addition to Hg in reaction ash & ash bellow particulate-collector are the essential distribution. Besides, the application of sorting devices for reduction of heavy-metal content, the resource-recovery as essential material of brick or road for bottom ash in addition to resource recovery by chemistry extraction of importment heavy-metal content in fly ash (others except bottom ash) before further treatment are suggested strongly.