垃圾焚烧典型工段灰/渣理化特性及环境风险性

Physicochemical characteristics and environmental risk of ash/slag in typical sections of MSW incineration

研究了垃圾焚烧典型工段5种灰/渣样品(余热锅炉灰/渣S1、半干法脱酸灰S2、布袋除尘灰S3、飞灰原灰S4和螯合剂稳定化飞灰S5)的表观特征、化学特性和浸出特性,并评估了灰/渣样品赋存重金属的环境风险。结果表明:S1呈现与其他灰样显著的表观特征差异,其表观颜色泛黄,颗粒大小不均,Si、Al含量较高,可资源化利用潜力较大;S3可溶性氯盐、高毒性重金属(Pb、Cd)含量较高,可进行单独脱氯、解毒处理;S5粒径级配在7~20μm和40~120μm存在两处波峰,其稳定化效果存在一定缺陷。S1赋存Cr(4.45%)和S3赋存Pb(3.04%)、Cd(4.28%)的可交换态和碳酸盐结合态占比相对较高,表明其潜在浸出环境风险较高,在其无害化处理和资源化利用过程中需重点关注,尤其是酸性(如酸雨或渗滤液浸沥)处置或应用场景。S1赋存重金属的潜在环境风险远低于其他4种灰样;模拟渗滤液浸提环境下,5种灰/渣浸出液重金属的综合性环境风险水平均高于模拟酸雨浸提环境,且S1、S3、S4和S5中Cd的浸出环境风险水平表现为“极强”等级。研究结果可为垃圾焚烧典型工段灰/渣的分类利用、精细化管理以及科学的环境风险评估提供理论依据。

The apparent,chemical,and leaching characteristics of five types of ash/slag samples(waste heat boiler ash/slag S1,semi-dry deacidification ash S2,bag dust removal ash S3,raw fly ash S4,and chelator stabilized fly ash S5)in typical sections of MSW incineration were studied,and the environmental risks of heavy metals in ash/slag samples were evaluated.The results showed that S1 exhibited significant differences in apparent characteristics compared to other samples,with a yellowing color,uneven particle size,and high Si and Al content,indicating a great potential for resource utilization.A higher content of soluble chloride salts and highly toxic heavy metals(Pb,Cd)were enriched in S3,which could be treated separately for dechlorination and detoxification.In terms of particle size distribution,there were two peaks in the range of 7—20μm and 40—120μm for S5,which had certain defects in its stabilization effect.The exchangeable and carbonate bound states of Cr(4.45%)in S1 and Pb(3.04%)and Cd(4.28%)in S3 were relatively high,indicating a high potential leaching environmental risk.Special attention should be paid to their harmless treatment and resource utilization,especially in acidic(such as acid rain or landfill leachate leaching)disposal or application scenarios.The potential environmental risk level of S1 containing heavy metals was much lower than the other four ash samples.Under the simulated landfill leachate leaching environment,the comprehensive environmental risk level of heavy metals in the five ash/slag leaching solutions was higher than that in the simulated acid rain leaching environment,and the leaching environmental risk level of Cd in S1,S3,S4,and S5 showed an“extremely strong”level.The research results could provide theoretical basis for the classification and utilization of ash/slag in typical MSW incineration sections,refined management,and scientific environmental risk assessment.