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预处理飞灰重金属的固定化效果及环境影响评估

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针对垃圾焚烧飞灰广泛存在重金属超标的问题,采用哌嗪螯合剂、二甲基二硫代氨基甲酸盐及水泥对飞灰进行预处理,以降低填埋风险.通过《固体废物浸出毒性方法醋酸缓冲溶液法》(HJ/T300-2007)探讨预处理对飞灰中重金属的固定效果,并采用X射线衍射、扫描电镜和BCR形态提取分析各飞灰的物相组成、微观形貌和重金属形态分布,使用RAC和STI模型对各飞灰进行环境风险评估.结果表明,原灰中重金属Ni、Pb、Cd的浸出毒性超标,重金属含量呈Zn>Pb>Cu>Cd>Cr>Ni顺序分布.预处理作用后,飞灰中重金属Ni、Cd、Pb的浸出毒性满足标准限值,固定率达99%以上,未超标重金属Cr、Zn、Cu的固定率高于96%.同等添加量下,SDD的稳定效果优于TS300,但TS300协同水泥固定重金属的作用优于SDD.稳定化对Cr的处理效果优于固化/稳定化,单一水泥固化对Zn、Pb、Ni的固定作用最佳,但40%的水泥用量及高增容比限制了水泥固化的应用.ANC测试表明,水泥固化的ANC最强.XRD和SEM分结果表明,稳定化形成的新矿物对重金属的固定起重要作用,水泥水化生成的Ca(OH)2和C-S-H通过物理吸附等作用将重金属包裹固定.BCR形态提取结果表明,预处理降低了重金属不稳定态的比重.RAC与STI模型评估结果表明,重金属Zn、Pb、Cd是环境风险的主要贡献者,相较于RAC指数法,STI模型的评估结果更符合预期.
Immobilization effect and environmental impact assessment of heavy metals in pretreated fly ash
In view of the widespread problem of excessive heavy metals in waste incineration fly ash,the fly ash was pretreated with piperazine chelating agent,dimethyl dithiocarbamate and cement to reduce the landfill risk.The fixation effect of pretreatment on heavy metals in fly ash was investigated by means of acetic acid buffer Solution Method for solid waste leaching Toxicity(HJ/T300-2007),and the phase composition,microscopic morphology and heavy metal morphological distribution of fly ash were analyzed by X-ray diffraction,scanning electron microscopy and BCR morphological extraction.The RAC and STI models were used to assess the environmental risk of each fly ash.The results showed that the leaching toxicity of heavy metals Ni,Pb and Cd in raw ash exceeded the standard,and the heavy metal contents were distributed in the order of Zn>Pb>Cu>Cd>Cr>Ni.After pretreatment,the leaching toxicity of heavy metals Ni,Cd and Pb in fly ash met the standard limit,and the fixation rate was more than 99%,and the fixation rate of heavy metals Cr,Zn and Cu was higher than 96%.The stabilization effect of SDD was better than that of TS300,but the effect of TS300 on cementing heavy metals was better than that of SDD.The effect of stabilization on Cr was better than that of solidification/stabilization.Single cement curing had the best fixing effect on Zn,Pb and Ni,but the application of cement curing was limited by 40%cement dosage and high-capacity ratio.ANC tests showed that cement solidified ANC was strongest.XRD and SEM results showed that the new minerals formed by stabilization played an important role in the fixation of heavy metals.Ca(OH)2 and C-S-H formed by cement hydration can bind heavy metals through physical adsorption.The results of BCR morphology extraction showed that pretreatment reduced the proportion of unstable heavy metals.The evaluation results of RAC and STI model showed that heavy metals Zn,Pb and Cd were the main contributors to environmental risks.Compared with the RAC index method,the evaluation results of STI model were more in line with expectations.

waste incineration fly ashstabilizationsolidification/stabilizationleaching toxicityimmobilization effectenvironmental risk assessment

杨延梅、郭明坤、王菲、慕宗宇、杨玉飞

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重庆交通大学河海学院,重庆 400000

中国环境科学研究院固体废物污染控制技术研究所,北京 100012

北京师范大学水科学研究院,北京 100085

垃圾焚烧飞灰 稳定化 固化/稳定化 浸出毒性 固定效果 环境风险评估

国家重点研发计划项目

2021YFE0112100

2024

环境工程学报
中国科学院生态环境研究中心

环境工程学报

CSTPCD北大核心
影响因子:0.804
ISSN:1673-9108
年,卷(期):2024.18(3)
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