The Evaluation of Organic Carbon Leaching from Acidic Wash and the Environmental Monitoring of Municipal Solid Waste Incineration Bottom Ash Used in Road Application
Date Issued
2010
Date
2010
Author(s)
Wu, Yi-Chi
Abstract
According to the statistics from Taiwan Environmental Protection Administration, the percentage of municipal solid waste incineration (MSWI) was increased from 55% to 96% since 2001. Although incineration could reduce the volume of the solid waste significantly, it produces large amount of fly ash and bottom ash. In 2009, overall bottom ash production from all incinerations in Taiwan was 850,000 tons. The utilization of MSWI bottom ash as road pavement has been widespread in Japan, Europe and North America. Some long term monitoring studies were completed, such as ten-year evaluation in France. The aim of this study was to monitor a test road located in Wanli, Taipei County, which was constructed with local MSWI bottom ash. . The environmental impact assessment of bottom ash utilization would be base on analyzing pH, conductivity, Cl- and DOC (dissolved organic carbon). The analysis results of surface water and ground water have been stable since the beginning. The leachate pH, conductivity and concentrations of Cl- and DOC concentration drop down quickly during the first 1.5 years and gradually reach the minimum values over 4 years, as well as heavy metals. In the later monitoring, the leachate concentration of Zn has been gradually increased due to the same status in surface water probably. Moreover, the portion of eluted heavy metals from bottom ash was estimated. The results show that As and Cd had the highest elution potential as 2.87% and 1.52% , respectively.
Another objective for this study was to test the organic carbon leaching properties from MSWI bottom ash. The bottom ashes were collected from Xindian, Bali and Zhuyin incineration plants. In order to reduce the heterogeneity of the bottom ash, different batches of sample were collected. The basic analysis results shows the moisture content of stabilized bottom ash was approximately 17%, ignition loss was 3.8% and no toxic chemical was found to over the regulation limits from TCLP tests. In acid extraction test, the elution of dissolved organic carbon (DOC) and heavy metals were corrrelated to the liquid to solid ratio (L/S). The best DOC extraction efficiency was found under the condiction as L/S=20, and Zn was the major heavy metal eluted. However, when L/S=5 and 10 the major eluted heavy metals were Ba and Cu intead of Zn.
Subjects
MSWI bottom ash
acidic wash
road application monitoring
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