垃圾渗沥液腐蚀下污泥灰改性黏土压缩特性及孔隙结构

采用市政污泥为原材料烧制污泥灰,并将污泥灰作为改良添加剂对传统填埋场压实黏土衬垫系统进行改性,以达到实现污泥资源化利用以及减少黏土作为衬垫防渗材料的用量.为评价污泥灰改性黏土作为填埋场衬垫材料的工程特性以及微观结构,通过固结压缩试验、低温氮气吸附试验、颗粒分析试验分别检测改性黏土的压缩特性、微观孔隙结构、颗粒组成.压缩试验结果表明,受垃圾渗沥液腐蚀后的改性黏土,随污泥灰含量的增加,孔隙比增大、压缩量减小;经垃圾渗沥液腐蚀后,改性黏土的压缩系数(α1-2)为0.310~0.391MPa-1,固结系数(Cv)为2.446~2.768cm2/s.低温氮气吸附试验结果表明,改性黏土的吸附-脱附等温线属于Ⅴ型等温线;对于垃圾渗沥液腐蚀的改性黏土,孔径分布呈双肩峰形式,孔径为3~7nm的孔隙占比较大,累计孔容为0.509~0.530cm3/g.颗粒分析试验结果显示,受渗沥液腐蚀后改性黏土颗粒组成差异性明显,粒径>11.5 μm的颗粒为35.09%~49.42%;粒径为2.3~1.5 μm的颗粒为2.35%~7.28%;粒径<2.3 μm的颗粒为46.57%~57.63%.污泥灰改性黏土具有较好的抗垃圾渗滤液腐蚀效果,可将其作为填埋场衬垫材料使用.

Compression properties and microstructure of modified clay containing SSA under landfill leachate

In order to reduce clay amount needed in the landfill liner system and recycle the sewage sludge, the sewage sludge ash (SSA), which was produced in the burning of sewage sludge, was used to improve the traditional liner system. To estimate the engineering properties of the landfill compacted clay liner system containing SSA, the consolidated compression test, the low temperature nitrogen adsorption test, the particle size analysis test were performed to determine the compression characteristic, the micro pore structure, the grain composition of the compacted clay modified by SSA. The result of the consolidated compression test indicated that with the increasing of the SSA content, the void ratio of the modified clay contaminated by the landfill leachate increased and the amount of the compression of it was decreased. After the modified clay was contaminated by landfill leachate, the compressibility and consolidation coefficients of the modified clay were separately between 0.310~0.391MPa-1, 2.446~2.768cm2/s. The low temperature nitrogen adsorption test suggested that the adsorption-desorption isotherm of the modified clay contaminated by landfill leachate belonged to V kind. The shoulder peak existed on the curve of the pore size distribution. The curve showed that the amount of pore between 3~7nm was larger and the accumulated pore volume was between 0.509~0.530cm3/g. The content of pore larger than 11.5μm was 35.09%~49.42%, the content of pore between 2.3~11.5μm was 2.35%~7.28%, and the content of pore smaller than 2.3μm was 46.57%~57.63%. Hence, the compacted clay containing SSA can efficiently resist corrosion, and it can be applied to landfill liner system.