Study on the Permeability of Modified Bentonite Slurry in Landfill

Zenan Zhang,Yanmin Sheng,Guozhong Dai,Charles C Sorrell

doi:10.1155/2020/8970270

Abstract

The impermeability of cutoff wall is one of the most important factors affecting the life of landfill. Hence, we used sodium carboxymethyl cellulose to modify bentonite and developed a modified bentonite-cement-fly ash antiseepage slurry with a low permeability coefficient. The main material of the slurry is bentonite modified by sodium carboxymethyl cellulose, cement, fly ash, and auxiliary materials such as sodium carbonate and polycarboxylate superplasticizer. The optimal ratio of the basic components of the antiseepage slurry was optimized by the orthogonal test method. The permeability coefficient of the consolidated slurry was determined by a variable head permeameter. The optimal dosage of each component of slurry is 210∼220 kg/m3 cement, 210∼220 kg/m3 bentonite, 1.5∼2.5 kg/m3 sodium carbonate, 1.5∼2.0 kg/m3 sodium carboxymethyl cellulose, 160 kg/m3 fly ash, and 3 kg/m3 polycarboxylate superplasticizer. The 28-day consolidation slurry permeability coefficient is less than 1 × 10−8 cm/s and has a good adsorption effect on the pollutants in landfill leachate.

Highlights

In recent years, with the rapid development of urbanization in China, the number of urban population is expanding day by day [1]
According to the orthogonal experiment results, with 210 kg/m3 cement, 210 kg/m3 bentonite, 2.0 kg/m3 sodium carbonate, and 1.5 kg/m3 sodium carboxymethyl cellulose, except for water, the content of other materials is not changed into the benchmark ratio. e control cement content is 210∼250 kg/m3, and bentonite content is 200∼240 kg/m3
Results and Discussion e critical pore size reflects the connectivity degree of pores and the tortuous degree of permeation path in the material, which is the essence of permeability. e permeability coefficient is determined by the critical pore size of the slurry

Summary

Introduction

With the rapid development of urbanization in China, the number of urban population is expanding day by day [1]. Polluted groundwater cannot be used as domestic water source, which will seriously affect people’s use of natural resources It will contaminate the surrounding soil, which cannot be used as farmland or forest land [16]. How to effectively control and treat landfill leachate has become one of the unavoidable problems in environmental geotechnical engineering. It is stipulated in the technical specification for sanitary landfill of municipal solid waste issued that proper artificial seepage prevention measures must be established for landfill sites that do not have natural seepage prevention conditions and landfill leachate that may pollute underground water sources [22,23,24]. A self-made adsorption percolation device was used to detect the adsorption effect of slurry consolidation diagram on the main pollutants

Experiment

D CMC-Na

A2 A3 A4 A5 B1 B2 B3 B4 B5

Conclusion