利用改性生物质电厂灰钝化修复北方Cd污染土壤的试验研究

Remediation of Cd-contaminated cropland soil in northen China via the amendment of modified biofuel ash

为钝化修复我国北方Cd污染农田提供一种经济有效的方法,选取我国北方生物质发电厂的灰渣为原料,经改性制成重金属钝化剂,开展等温吸附试验、盆栽试验和原位修复试验的研究。研究结果表明:制备的钝化剂在水中对Cd的吸附性能高于粉煤灰,最大吸附量达10 mg·g-1以上;且中性条件下,沉淀量对总吸附量的贡献率不到30%。盆栽试验中,添加土壤干重3%的钝化剂,稻米Cd降低80%以上;添加2%的钝化剂,小白菜叶Cd降低90%以上。原位试验中,添加1%的钝化剂,玉米根Cd降低53.5%,Pb降低64.4%,产量增加20.5%;添加2%的钝化剂,小麦籽粒Cd降低33%,产量增加72.5%。基于我国北方生物质电厂灰渣制备的钝化剂,主要化学成分为硅、钾、钙等生物有益元素,重金属安全风险很低。

To provide an excellent way for the remediation of Cd-contaminated cropland in northen China,the bottom ash of the biomass power plant in northen China was selected to produce a heavy metal deactivator(HMD).Isothermal adsorption experiments,pot experiments,and in situ experiments were conducted.The maximum adsorption capacity for Cd was over 10 mg·g^1 and was much higher than that of coal fly ash;the contribution rate of precipitation to total adsorption was less than 30%when the pH of adsorption equilibrium solution was neutral.According to the results of the pot experiments,with the amendment of 3%W/W HMD to soil,the Cd in rice decreased over 80%,and with the amendment of 2%W/W HMD,the Cd in cabbage leaves decreased over 90%.The in situ experiments showed that,with the amendment of 1%W/W HMD,the Cd and Pb in corn root decreased by 53.5%and 64.4%,respectively,and production increased by 20.5%;whereas with the amendment of 2%W/W HMD,the Cd in wheat seed decreased by 33%and production increased by 72.5%.The main chemical composition of HMD made by the bottom ash of the biomass power plant in northen China is silicon,potassium,and calcium,and the risk from its heavy metal content is very low.