改性生物质电厂灰钝化修复南方镉污染土壤及其长效性研究

选取我国南方生物质发电厂的灰渣为原料，经物理和化学改性制成重金属钝化剂，针对我国南方重金属Cd污染的土壤开展钝化修复研究.底灰中Cd等重金属含量明显低于其对应的飞灰，这是选择底灰作原料的重要原因.用其制备的BFA型钝化剂在水中对Cd的吸附量可达16mg/g以上.室内盆栽试验中，添加土壤干重1%的钝化剂，第一季稻米Cd含量降低80%以上，从超标2.8倍降至达标；第二季小麦籽粒Cd降低70%，从超标0.9倍降至达标.在我国南方Cd重度污染的农田中开展的原位修复试验表明，添加1%的钝化剂，稻米和小麦籽粒中Cd降低70%~90%，其中稻米Cd持续降低，2017年降低率相较2016年继续提升10%~20%，最终从超标20倍降至达标；Ni降低60%以上，且保留有益的Cu、Zn元素不受明显影响；此BFA型钝化剂还能促进作物生长，第一季稻米产量提高40%~60%，第二季仍有一定的增长效果.综合安全性考虑，我国南方生物质电厂的灰渣重金属含量很低，经过改性加工可制成安全高效的重金属钝化剂.可为钝化修复我国南方重金属污染农田提供一种经济有效的方法，也为现阶段难以处置的灰渣提供一个重要的利用途径.

Remediation of Cd-contaminated cropland soil in South China with the amendment of modified biofuel ash and its long-term effects

The bottom ash of biomass power plant in South China was used to produce heavy metal deactivator BFA by physical and chemical modification, BFA was used to remediate the cadmium contaminated soil in South China. The reason why we selected the bottom ash was the content of heavy metals such as Cd in bottom ash were significantly lower than that in fly ash. The adsorption capacity of BFA to Cd in water was over 16mg/g. The results of indoor pot experiment showed that, with the amendment of 1% w/w BFA to soil, Cd in rice decreased over 80% in the first season, from 2.8times over the national standard value to lower than the standard; in the second season, Cd in wheat decreased by 70%, from 0.9times over the standard value to lower than the standard. The in situ experiment conducted in the heavily polluted cropland in South China showed that, with the amendment of 1% w/w BFA to soil, Cd in rice and wheat produced decreased by 70%~90%, in the second year (2017), the Cd reduction rate in rice increased by 10%~20% compared with the first year (2016), from 20times over the standard value to lower than the standard. By the way, the Ni in rice and wheat produced decreased over 60%, while the content of beneficial elements, such as Cu and Zn, were not affected signally. the BFA also promoted crop growth, the yield of rice increased by 40%~60% in the first season and still have benificial effects in the second season. The heavy metal content of the bottom ash of biomass power plant in south China is low. The BFA produced by the bottom ash provides an excellent way to dispose of the bottom ash and for the remediation of cropland contaminated with heavy metals in South China.