摘要
固化污染土的环境效应是废土二次应用过程中需研究的工程问题。以镉、铅、镍污染土为研究对象,通过固化率指标初筛适宜固化材料配比,模拟干湿循环、长期浸水、高温、冻融循环环境,以浸出毒性指标评价水泥、水泥+粉煤灰、石灰固化后土体的环境效应,并结合微观形态及重金属形态分析,评价失稳机制。结果表明:无机材料可将土中重金属的固化率提高至90%以上,8%的石灰适用于镉污染土的固化,32%+8%的水泥+粉煤灰适用于铅及镍污染土的固化。水环境(干湿、浸水)条件下固化污染土均不存在环境风险,其浸出毒性均低于《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3-2007)中的限值;但无机材料固化污染土对温度(高温、冻融)敏感,特别是水泥、水泥+粉煤灰固化污染土,在温度超过70℃时的浸出毒性超过标准中限值,在冻融循环5~7次时接近标准限值。高温会促使重金属赋存形态从稳定态向非稳定态转化,冻融循环会破坏重金属-固化产物体系的结构。无机材料固化重金属污染土的应用需要考虑环境温度的影响。
The environmental effect of solidified contaminated soil is an engineering issue that needs to be studied in the process of waste soil reapplication.Taking cadmium,lead and nickel contaminated soil as the research object,through the initial screening of the curing rate index,the suitable curing material ratio,simulating wetting and drying cycles,long-term water immersion,high temperature,freeze-thaw cycles environment,and evaluate the environmental effects of soil after cement,cement+fly ash and lime solidification by the leaching toxicity index,combined with microscopic and heavy metal morphology analysis,evaluate the instability mechanism.The result shows that inorganic materials can increase the solidification rate of heavy metals to more than 90%,8%lime is suitable for the solidification of cadmium contaminated soil,and 32%+8%cement+fly ash is suitable for lead and nickel contaminated soil.Solidification of contaminated soil under water environment(wetting and drying,water immersion)has no environmental risk,and its leaching toxicity is lower than the limit in the Identification standard for hazardous wastes:Identification for extraction toxicity(GB 5085.3-2007);but solidification contaminated soil is sensitive to temperature(high temperature,freeze-thaw),especially cement,cement+fly ash solidified contaminated soil,when the temperature exceeds 70℃,the leaching toxicity exceeds the standard limit,and it is close to the freeze-thaw cycles 5-7 times the standard limit.High temperature will promote the transformation of the occurrence of heavy metals from a stable state to an unsteady state.The freeze-thaw cycles will destroy the structure of the heavy metal-solidified product system.The application of inorganic materials to solidify heavy metal contaminated soil needs to consider the influence of environmental temperature.
作者
李敏
张然然
田冰雪
LI Min;ZHANG Ranran;TIAN Bingxue(School of Civil and Transportation Engineering,Hebei University of Technology,Tianjin 300401,P.R.China;Hebei Research Center of Civil Engineering Technology,Hebei University of Technology,Tianjin 300401,P.R.China)
出处
《土木与环境工程学报（中英文）》
CSCD
北大核心
2024年第4期202-210,共9页
Journal of Civil and Environmental Engineering
基金
国家自然科学基金(51978235)
河北省自然科学基金(E2018202274)
河北省科技创新战略基金(20180602)。
关键词
重金属污染土
固化污染土
固化配比
环境效应
失稳机制
浸出毒性
heavy metal contaminated soil
solidified contaminated soil
curing ratio
environmental effects
instability mechanism
leaching toxicity
