Geotechnical Characterization of Biochar-Based Biocover

Abstract

Landfills are one of the major sources of methane (CH4) emission which is a very potent greenhouse gas. The use of a natural process for microbial CH4 oxidation through biocovers provides a source reduction of CH4 emission. Previous studies have mostly focused on biochemical properties, and limited research has been conducted with regards to the geotechnical characterization of biochar based biocovers. This paper presents the results of a comprehensive laboratory investigation on laterite, Igbokoda sand and their mixtures with biochar at 2%, 4%, 8%, 10% and 20% to determine the compaction properties of biochar based biocovers. From the result, it was shown that the laterite has medium plasticity while the Igbokoda sand is non-plastic. Also, Addition of biochar to landfill cover soil increased the particle sizes, and consequently the porosity of the soil is increased which can promote the air flow through the landfill cover. Thus, greater O2 diffusion within the landfill cover will result, leading to higher microbial oxidation/degradation of CH4. Maximum dry unit weight decreased and the optimum water content partly increased as the biochar content increased with the two samples. Compaction test results show that when biochar content varied from 0 to 20% for the laterite, the maximum dry unit weight decreased from 1660kg/m3 to 1330kg/m3 and decreased from 1590kg/m3 to 1390kg/m3 for Igbokoda Sand. Thus, the results presented in this paper will contribute to a better understanding of the geotechnical behaviour of biochar based biocover.