城市生活垃圾焚烧底渣在模拟酸雨条件下的浸出规律

生活垃圾焚烧底渣的资源化利用是解决底渣出路的最佳途径.我国大面积的酸雨区域使进入环境的底渣“浸泡”在弱酸性环境中,加速底渣中有毒有害物质在酸雨条件下的浸出浓度.通过模拟酸雨pH值范围,对不同粒径的生活垃圾焚烧底渣进行浸取实验.结果表明:浸出液的平衡pH值随浸取时间增大,而重金属的浸出浓度变化比较复杂.随着浸取时间延长,重金属浸出浓度越来越小.浸出液中不同重金属的浸出浓度差异很大,镉、铬、铜、铅、镍的浸出浓度均低于危险废物鉴别标准-浸出毒性鉴别(GB5058.3-1996)的最低允许值.由于浸取初期重金属的浸出浓度很高,如果底渣未经稳定化处理直接进入环境进行资源化利用将对环境造成二次重金属污染.

Leachability of Heavy Metals In MSW Incineration Slag Under Simulated Acid Rain Condition

Utilization as resource is the best way to dispose the MSW incineration slag.However,the huge acie-rain district in China increases the potential risk from heavy metals leaching from the slag.In this paper,a lot of experiments were carried to simulate the acid-rain pH values to investigate the leachability of heavy metals in the slag under the different acid-rain conditions.The Experimental results showed that(1)The initial pH values had significant effect on the leaching concentrations of Cu,Cr,Cd,Ni and Pb;the leaching concentration of heavy metals were decreased with time on and with the increased equilibrium pH value.(2)The concentrations of Cu,Ni and Cr in the leachate were significantly higher than those of Pb and Cd.(3) Although the leaching concentrations of heavy metals were below their respective limits in GB5058.3-1996(Hazardous waste identification standard),the slag can not be utilized as resource without any pre-treatment for heavy metals because their initial leaching concentrations were rather high.