Saturated Hydraulic Conductivity of Municipal Solid Waste Considering the Influence of Biodegradation

Municipal solid waste (MSW) permeability is influenced mainly by compaction, unit weight, overburden pressure, composition, and biodegradation of the waste. However, the variation of hydraulic conductivity with MSW biodegrading over time has not yet been sufficiently studied, and consequently not fully understood. This study aimed to present the saturated hydraulic conductivity (Ksat) of the MSW, considering the influence of anaerobic biodegradation, by using two large-scale rigid wall permeameters (P1 and P2) in two experimental groups. The leachate produced was subjected to physicochemical analysis. The MSW confined in both permeameters presented similar gravimetric composition and total mass but diverse initial unit weight, ranging from 4.9 to 7.2kNm-3. Maximum and minimum values of Ksat obtained for the confined MSW were 2.0x10-2ms-1 and 7.4x10-6ms-1, respectively. Physicochemical analysis indicated that MSW biodegradation in permeameters remained in the anaerobic acid phase. The methodology adopted for the permeability tests influenced the MSW biodegradation, and consequently its hydraulic behavior. It is believed that, during 7days before the permeability tests, the drained gas changed the MSW mass structure into the permeameters and the Ksat values over time. Within the permeameters with higher unit weight MSW, the Ksat values increased for up to 3months, tending to stabilization.