To Recover Heavy Metals and Stabilize Fly Ash from Municipal Waste Incinerator by Electro-Deposition Process

• Main Authors: Sing-Chia Wang, 王薪嘉
• Other Authors: Wing-Ping Liao
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/06313512490972821683

碩士 === 國立中興大學 === 環境工程學系所 === 96 === In the past years in Taiwan, the main way to deal with domestic wastes in the 1980’s was landfill, in the 1990’s was incineration, and in the 2000’s was resource recycling and reuse. In June 2007, the proper treatment efficiency of domestic wastes was raised to 99.76%. From 2007, the environmental rule stated that domestic wastes can’t be allowed to the landfill without any treatment, but must be dealt with incineration. According to EPA statistic in Taiwan, every 1.0 kg of MSWI (Municipal Solid Waste Incinerator) wastes incineration will produce about 0.04 kg of fly ash, and the original MSWI fly ash TCLP (Toxicity Characteristic Leaching Procedure) test results showed that heavy metal concentration of lead was several times higher than other heavy metals, which over the environmental standard limits was up to 52.9%, and the MSWI ash of reutilization efficiency was only about 40.9% in 2007, that the primary technology of disposal of MSWI fly ash was still solidification and landfill. This will make MSWI fly ash turn to the heavy metal of underwater pollution. Thus was the subject to the bioavailability study. Based on zero waste and reuse policy of domestic wastes, the study mainly treated MSWI fly ash by electrodeposition process. Including sampling of the three different MSWI fly ash was called Ash-A, -B, -C, and testing of TCLP,sequential extraction procedure and bioavailability study,the focus was before and after the electrodeposition process. The results showed that Ash-A and -B''s lead, Ash-C''s copper were in the weak phase of the highest proportion,so these heavy metals had the highest removal efficiency by electrodeposition process. Otherwise, on the bioavailability after the electrodeposition process, these heavy metals compared with the original fly ash which was reduced. The reducing percentage of Ash-A and -B''s lead was 56.4% and 76.1% respectively, and the Ash-C of Copper was 93.2%. In addition, the three ashes of the chloride concentration were significant decline (18.9% → 8.2%, 16.0% → 6.7%, 2.3% → 0.07%). The results showed that the lead of electrodeposition fly ash could pass TCLP standard limits, and the electrodeposition fly ash was worthful used as the resources. Comparing with several different treatment technology: electrodeposition process and water washing combined with electrokinetic process, both fly ash can pass TCLP standard limits, but the total removal efficiency of heavy metals in fly ash wasn’t significant.