Xu Shuyuan, Zhang Yongbo, Guo Jiangbo, Wu Aijing, Xiang Xinghua, Sun Haodong
Department of Geology and Surveying Engineering, Shanxi Institute of Energy, Taiyuan, 030600, China.
Geological Environments and Disaster Prevention and Reduction Research Center, Shanxi Institute of Energy, Taiyuan, 030600, China.
Sci Rep. 2025 Jan 22;15(1):2758. doi: 10.1038/s41598-025-86591-x.
In China, a significant amount of coal fly ash is stored or used for landfill reclamation. The contaminants in coal fly ash (CFA) leachate can cause regional soil and groundwater contamination during long-term storage. This paper focuses on a coal gangue comprehensive utilisation power plant in Fenyang City, Shanxi Province, China, where the leaching characteristics of CFA were investigated by leaching tests. Laboratory-scale long-term soil column leaching tests and long-term ash column leaching tests were conducted using compacted soil and compacted CFA, respectively, to simulate contaminant migration patterns from CFA during the early and later stages of landfill operation. Hydrus-1D simulation software was used to calculate contaminant transport from the CFA landfill. The test results indicate that the concentrations of six representative elements or compounds in the CFA leachate exceeded the Groundwater Standard Class III. Among these contaminants, Pb contamination was the worst, with concentrations 26.67 times above the standard. The flow rate of the leachate is lower when the degree of compaction of the Ma'lan loess and the CFA is higher, and it takes longer for the leachate to start flowing. The greatest release of the ions occurred at a Ma'lan loess compaction coefficient of 0.943 and a hydraulic conductivity of 6.031 × 10. Under extreme rainfall conditions, the contaminants and heavy metals in the fly ash leachate migrate to a maximum depth of 56 cm in the compacted soil layer, with Pb reaching a depth of 28 cm, nickel 23 cm, cadmium 9 cm and hexavalent chromium 5 cm to meet Class III groundwater quality standards. These results indicate a potential risk of groundwater contamination in the vicinity of CFA deposits or land reclamation projects in long-term storage. To mitigate this risk, the Guofeng Power Plant may consider utilizing locally compacted Malan loess in combination with geosynthetic materials or implementing a liner much thicker than 1.5 m to enhance the impermeability of the fly ash landfill.
在中国，大量的粉煤灰被储存或用于填埋场复垦。粉煤灰渗滤液中的污染物在长期储存过程中会导致区域土壤和地下水污染。本文聚焦于中国山西省汾阳市的一座煤矸石综合利用发电厂，通过淋溶试验研究了粉煤灰的淋溶特性。分别使用压实土壤和压实粉煤灰进行了实验室规模的长期土壤柱淋溶试验和长期灰柱淋溶试验，以模拟填埋场运营早期和后期粉煤灰中污染物的迁移模式。利用Hydrus - 1D模拟软件计算粉煤灰填埋场中污染物的运移情况。试验结果表明，粉煤灰渗滤液中六种代表性元素或化合物的浓度超过了《地下水质量标准》Ⅲ类。在这些污染物中，铅污染最为严重，浓度超标26.67倍。当马兰黄土和粉煤灰的压实程度较高时，渗滤液的流速较低，渗滤液开始流动所需的时间更长。离子的最大释放量发生在马兰黄土压实系数为0.943、水力传导率为6.031×10时。在极端降雨条件下，粉煤灰渗滤液中的污染物和重金属在压实土层中的最大迁移深度为56厘米，铅达到28厘米深度，镍达到23厘米深度，镉达到9厘米深度，六价铬达到5厘米深度，以满足Ⅲ类地下水水质标准。这些结果表明，长期储存的粉煤灰堆场或土地复垦项目附近存在地下水污染的潜在风险。为降低这种风险，国峰电厂可考虑采用当地压实的马兰黄土并结合土工合成材料，或实施厚度远大于1.5米的衬层，以增强粉煤灰填埋场的防渗性。
