engleski

Short- and long-term settlement properties of MBT waste

Mechanically and biologically treated (MBT) municipal solid waste (MSW) has modified compression properties with respect to untreated MSW. In MBT plants that utilize the biodrying treatment process, MSW is separated into several recyclable streams (i.e., plastics, metals, and RDF), while the organically rich reject fraction (ORRF) has to be deposited into the MBT bioreactor landfill (BL). In the MBT BL, leachate passes through the landfill body in order to enhance the decomposition of organic compounds and accelerate methane production for energy recovery purposes. While the described methodology is beneficial to the environment, it can also cause significant difficulties in the operating conditions of a BL. Namely, increased moisture content and unit weight, and decreased effective stresses and rapid biodegradation will induce additional settlement of a landfill body. Therefore, for the proper design of an MBT BL, the compression properties of the ORRF have to be thoroughly examined. Within this manuscript, the compressibility properties of the ORR fraction obtained from the waste management center (WMC) Marišćina in Croatia are presented. In order to simulate various operational stages of the MBT BL, four ORRF samples under different moisture conditions were tested: dry, wet, compression of an initially dry sample to a certain stress level, followed by wetting and continued loading, and long-term compression with induced biodegradation during which the temperature and generated landfill gases were recorded. The obtained results show that significant settlement of the landfill body, caused by the wetting procedure and degradation process, can be anticipated.

bioreactor landfill ; MBT ; MSW ; immediate settlement ; secondary compression

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