铬渣污染土壤稳定化技术研究

选用3种不同类型的铬渣污染土壤(A土、B土和C土)作为研究对象,探讨了6种稳定化药剂对污染土壤中Cr(Ⅵ)的还原效果,并研究了不同药剂对各形态Cr稳定化效果。结果表明:FeSO4和Na2S对Cr(Ⅵ)都有很好的还原效果,葡萄糖次之,Na2SO3效果一般,柠檬酸和腐植酸效果不好;FeSO4和Na2S对B土、C土中Cr(Ⅵ)的还原率达到90%以上,对A土中Cr(Ⅵ)的还原率则低于85%;稳定化药剂主要是将酸可提取态Cr转化为其他形态,FeSO4效果最明显,可将80%以上的酸可提取态Cr转化为其他形态,主要为可还原态Cr;葡萄糖主要将之转化为可氧化态Cr;鉴于FeSO4的良好的还原效果,选择FeSO4作为稳定化药剂,且FeSO4添加量为理论投加量的20时较合适,浸出液可以满足地下水三级标准的50μg/L;经济性分析,处理1t清洗后土壤的药品费用为8.91元。

STUDY OF STABILIZATION TECHNOLOGY OF CHROMIUM SLAG-CONTAMINATED SOIL

Three different types of chromium slag-contaminated soils were selected as test samples to investigate the hexavalent chromium reduction efficiencies of six stabilization agents.And the stabilization efficiencies of different stabilization agents on different fractions of chromium in soils were measured.The main findings were as follows: the hexavalent chromium reduction efficiencies of FeSO4 and Na2 S were the best of six stabilization agents.And glucose had better efficiency than Na2SO3.However,citric acid and humic acid had bad efficiencies.The hexavalent chromium reduction efficiencies of FeSO4 and Na2S were both more than 90% in soil B and soil C and were less than 85% in soil A.Cr with exchangeable and weak acid extracted fraction was mainly changed to other fractions by stabilization agents.And FeSO4 had the best efficiency.It could change more than 80% Cr with exchangeable and weak acid extracted fraction to other fractions which were primary reducible Cr fraction while which were primary oxidable Cr fraction with the use of glucose.Considering the best reduction efficiency of FeSO4,it is chosen for the stabilization agent.Meanwhile proper adding quantity of FeSO4 is 20 times more than theory adding quantity,and lixivium is up to 50 μg/L,which can meet Grade Ⅲ standard of groundwater.By economic analysis,the cost of medicine which used for one ton of washed soil treatment is RMB 8.91 yuan.