粉煤灰中污染物质的淋溶释放模型

LEACHING MODEL OF POLLUTANT IN FLY ASH

我国火电厂粉煤灰，全部为碱性灰，在自然淋溶条件下，淋出液中绝大多数重金属的含量一般较低，但是，ｐＨ值、ＳＯ_４^（２－）、Ｆ~－和Ｃｒ^（６＋）等项目经常超过生活饮用水卫生标准（ＧＢ５７４９－８５），ｐＨ值、Ｆ~－等项目甚至经常超过污水综合排放标准（ＧＢ８９７８－８８）新扩改一级，是粉煤灰中的主要污染因子。粉煤灰中不同污染因子受淋溶介质的影响不同，酸性介质有利于Ｃａ^（２＋），Ｆ~－的释放，碱性介质有利于Ｃｒ^（６＋）的释放，在各种介质淋溶下，主要污染因子的淋溶释放一般符合Ｃ_ｔ＝Ｇ_０~ｅ^（ｂｉｎｔ）模型。通过模型不仅可了解污染因子的释放能力及释放速度，而且可为灰场是否需要进行工程处理提供依据。此外，还可用于灰场对水环境污染的源强预测。

All fly ash of power station is alkaline in China. Concentrations of most heavy metals in leachate solution is generally lower under natural leaching conditions. Nevertheless, pH,SO_4￣(2-) , F￣- and Cr￣(6+) often exceed hygiene standard on drinking water (GB5749-85). Moreover, pH and F- often exceed comprehensive drainage standard on waste water (GB8978-88 ) .Ca￣(2+) and F￣- in ash are readily released in acid medium. Cr￣(6+) is readily released in alkaline medium. The leachation of main pollutants generally follow following equation under all kinds of conditions: Ct =C_0e￣(blnt). Mobility and release speed of pollutant can be predicted by the equation. suggestion on whether of not the ash pond needs special antiseep layer can be provided by the model.