1 Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, USA.
2 Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL, USA.
Waste Manag Res. 2019 Sep;37(9):951-955. doi: 10.1177/0734242X19864651. Epub 2019 Aug 5.
The use of municipal solid waste incinerator bottom ash for road-base construction is an accepted practice in Europe and Asia, and of growing interest in the US. It is common practice to cure bottom ash by stockpiling it for several weeks before using it in this application. The curing process exposes the bottom ash to atmospheric carbon dioxide, which promotes carbonation, lowering its pH (making it less alkaline), and making many heavy metals less soluble. While this process makes bottom ash a more environmentally acceptable material, it takes time and requires additional handling. This article investigates a concept to facilitate carbonation of bottom ash in its compacted state, potentially eliminating the stockpile curing process. It is demonstrated here that blending a small amount of organic material with bottom ash will accelerate carbonation and lower pH in compacted samples by providing a carbon source for bacteria to produce carbon dioxide. Different quantities of biosolids (1%, 2%, 3%, and 5% by mass) were added to compacted bottom ash samples to examine the effect of organic materials on carbonation, and results were compared with a compacted control bottom ash sample. The pH of the control bottom ash sample decreased from 12.07 to 9.78 after 63 days, while the pH of the sample containing 5% biosolids decreased from 11.70 to 9.74 in only 7 days and to 8.18 after 63 days. Physical testing was conducted to examine suitability for beneficial use. The results indicate that bottom ash containing less than 3% biosolids met minimum bearing strength requirements for road base.
在欧洲和亚洲，将城市固体废物焚烧炉底灰用于道路基层建设是一种被广泛接受的做法，在美国也越来越受到关注。在将底灰用于这种应用之前，通常将其储存数周以进行固化。固化过程使底灰暴露于大气中的二氧化碳中，从而促进碳酸化作用，降低其 pH 值（使碱性降低），并降低许多重金属的可溶性。虽然这一过程使底灰成为一种更环保的材料，但它需要时间并需要额外的处理。本文研究了一种促进底灰在压实状态下碳酸化的概念，可能会消除储存固化过程。这里证明，将少量有机材料与底灰混合将通过为细菌提供产生二氧化碳的碳源来加速压实样品中的碳酸化作用并降低 pH 值。将不同数量的生物固体（按质量计 1％、2％、3％和 5％）添加到压实的底灰样品中，以研究有机材料对碳酸化的影响，并将结果与压实的对照底灰样品进行比较。对照底灰样品的 pH 值从 12.07 降低到 9.78 ，而含有 5％生物固体的样品的 pH 值从 11.70 降低到 9.74 仅需 7 天，63 天后降低到 8.18 。进行了物理测试以检查其是否适合有益使用。结果表明，含有少于 3％生物固体的底灰满足道路基层的最小承载强度要求。
