水泥/粉煤灰/MgO固化对淤泥中重金属的固化效果及机理

Solidification effect and its mechanism of cement/fly ash/MgO on heavy metals in sludge

为了获得一种高效、资源稳定的城市淤泥固化配比技术,研究了淤泥∶水泥∶粉煤灰∶氧化镁∶重金属捕捉剂质量比分别为100∶3∶3. 5∶3. 5∶0. 1(SC3F3. 5M3. 5H0. 1)、100∶5∶2. 5∶2. 5∶0. 1(SC5F2. 5M2. 5H0. 1)和100∶7∶1. 5∶1. 5∶0. 1(SC7F1. 5M1. 5H0. 1)的固化配比对淤泥中重金属形态和浸出浓度的影响。结果表明:随着水泥含量的增加,重金属固化效果增强;淤泥固化处理后,重金属由非稳定态向稳定态转化,其中碳酸盐结合态和Fe-Mn氧化物结合态是主要的被固化成分。当采用SC5F2. 5M2. 5H0. 1配方固化处理后,各重金属的浸出浓度均达到GB5085. 3-2007标准限值,且固化成本低和废物再利用率最高。重金属被固化是由水泥、氧化镁、粉煤灰和捕捉剂等协同作用的结果,其机理包括共沉淀、吸附、螯合、包裹等作用。

In order to obtain an efficient,resource-efficient and stable urban sludge solidification technology,the effect of sludge solidification formula which has different mass ratio of sludge∶cement∶fly ash∶MgO∶heavy metal chelating agent of 100∶3∶3.5∶3.5∶0.1(SC3F3.5M3.5H0.1)、100∶5∶2.5∶2.5∶0.1(SC5F2.5M2.5H0.1)and 100∶7∶1.5∶1.5∶0.1(SC7F1.5M1.5H0.1)on the morphology and leaching concentration of heavy metals in sludge were studied in this paper.The study results showed that with the increase of cement content,the solidification effect of heavy metals in sludge became better and better;the heavy metals in solidified sludge changed from unstable state to stable state,and carbonate bounded form and Fe-Mn oxides bound were the main solidified components.After solidification treatment of SC5F2.5M2.5H0.1,the leaching concentration of heavy metals in sludge all reached the standard limit of GB5085.3-2007,and the solidification treatment of SC5F2.5M2.5H0.1 had the minimum solidification cost and the maximum reuse efficient of waste.The solidification of heavy metals is mainly due to the joint action of cement,MgO,fly ash and heavy metal chelating agent,and its mechanism includes co-precipitation,adsorption,chelation and wrap.