城市污泥与玉米秸秆共热解重金属的形态变化

Heavy metal fraction changing via pyrolysis of sewage sludge with corn straw

采用重金属简单连续提取法提取城市污泥与玉米秸秆共热解所得炭粉中不同形态的重金属,利用电感耦合等离子体质谱仪检测Cr,Ni,Cu,Zn,Cd,Pb以及各重金属不同形态的含量,考察污泥秸秆共热解前后重金属形态的变化规律.结果表明：在不同热解条件下得到的炭粉,与热解前污泥比较,各形态重金属的可交换态和可动员态明显下降,在700℃热解温度下,残渣态比例明显增加到99%以上.随着秸秆添加量的增加,残渣态比例有所下降,但仅有0.01%~0.1%,且在30%的添加量下,残渣态比例下降最少.热解能使重金属由具有一定环境毒性的可交换态与可动员态转化为对环境基本无害的残渣态.

The short sequential procedure was employed for extraction of the heavy metals,including Cr,Ni,Cu,Zn,Cd and Pb,in different fractions from different carbon materials made by pyrolysis of sewage sludge with corn straw.The ICP-MS was used to detect the heavy metal content in order to study the fraction changing of heavy metal after pyrolysis.The results show that the fractions of heavy metals in the carbons obtained at different conditions obviously changed compared with the raw sludge,and the mobile and mobilization fractions of heavy metal decreased,while the residual fraction increased to nearly more than 99% of the total content of heavy metals at 700 ℃ of pyrolysis temperature.On the addition of the corn straw,the residual fractions reduce but only to about 0.01%-0.1%,and reduce to lowest when its quality ratio to sewage sludge is 30%.It can be concluded that the fractions of heavy metal in sewage sludge can be changed by pyrolyzing with corn straw from the mobile and mobilization fractions which have harmful effect on environment to the residual fractions which are very stable and almost harmless.