The Influence of biodegradation on the development of settlements in urban solid waste covered with an intermediate landfill cover

Abstract

This study aimed to verify the behavior of USW and OSW settlements due to biodegradation. Since biodegradation is responsible for a large part of the settlements in USW landfills, monitoring the biodegradation phases in which the mass of waste is located is essential. In this perspective, three lysimeters were built, 1 containing MSW and 2 containing OSW, all covered by an intermediate cover soil layer disposed of in landfills in Ceará State. The lysimeters were designed under surface drainage conditions (with and without slurry recirculation). The settlements were higher in the lysimeters containing only OSW than in the lysimeters containing USW. In the lysimeter without recirculation, there were decreases in COD, about the lysimeter with recirculated slurry. The slurry recirculation contributed to higher settlements and made the leachate more concentrated, with salts such as chlorides that directly influenced the increased electrical conductivity. The compaction of the intermediate cover layer of the landfill proved to be adequate since the degree of compaction was 95% of the Normal Proctor, with dry specific weight values of 18.2 kN/m³ in the field and 19.1 kN/m³ obtained in the laboratory.