不同浸提方法对固体废物中重金属浸出含量的影响

Effect of Different Leaching Methods on the leaching Content of Heavy Metals in Solid Waste

比较了4种浸提方法[水提法、毒性特征浸出程序(TCLP)、pH控制的改良TCLP和连续化学浸提法(SCE)]在不同的液固比(L/S)、pH和浸提剂类型下,对城市固体废弃物(MSW)焚烧炉空气污染控制(APC)残留物中重金属浸出质量浓度的影响。结果表明:用蒸馏水浸提时,当L/S在2~100 mL·g^(-1)范围内,所有重金属的浸出质量浓度均随着L/S的增加而降低,多数重金属的释放量随着L/S的增加而增加,且当浸出时间大于30 min后,浸出时间对于重金属浸出质量浓度和释放量的影响较小。在TCLP和改良的TCLP试验中,浸出质量浓度和重金属释放量(AHMR)都极依赖于浸提过程中的pH。在SCE实验中,碳酸盐结合态(CB)和Fe-Mn氧化态(OX)(易溶于酸的部分)在浸出的重金属中占比最高。此外,SCE和改良的TCLP试验中浸出的目标重金属量均远高于常规TCLP和水提法浸提的量。

The effects of four leaching methods(water extraction,toxic characteristic leaching procedure(TCLP),pH-controlled modified TCLP,and continuous chemical leaching(SCE))were compared at different liquid-solid ratios(L/S),pH and leaching agent types on heavy metal leaching mass concentrations in air pollution control(APC)residues from municipal solid waste(MSW)incinerators.The results showed that in the distilled water leaching experiment,when L/S was in the range of 2~100 m L·g^(-1),the leaching mass concentration of all heavy metals decreased with the increase of L/S,and the release of most heavy metals increased with the increase of L/S.And when the leaching time was longer than 30 min,the leaching time had little effect on the leaching mass concentration and release amount of heavy metals.In both TCLP and modified TCLP experiments,both the leaching mass concentration and the heavy metal release(AHMR)were strongly dependent on the pH during the leaching process.In the SCE experiment,the carbonate bound state(CB)and the Fe-Mn oxidation state(OX)(the part easily soluble in acid)accounted for the highest proportion of the leached heavy metals.In addition,the amount of target heavy metals leached in both SCE and modified TCLP tests were much higher than those leached by conventional TCLP and water extraction.