Experimental investigation of biochemical and geotechnical properties of municipal solid waste undergoing biodegradation for landfill design

Unscientific disposal of municipal solid waste (MSW) brings a remarkable change in MSWs physical, geotechnical, and biochemical properties, which is responsible for landfill design failures, leading to environmental pollution. Therefore, bioreactor landfill is one of the recent technologies used in India nowadays. Although the physical, engineering, and biochemical properties of MSW have extensively been studied, only a few researchers were reported to work on the behaviour and composition of MSW with degradation levels in a large bioreactor simulator. However, the behaviour of MSW is unpredictable with biodegradation due to its heterogeneous nature. The bioreactor landfills studies have yet to be explored in India. There is a need to examine this subject to continuously monitor bioreactor simulators during the long-term degradation of MSW. MSWs physical, geotechnical, and biochemical properties for landfill design undergoing biodegradation were investigated using specially designed large- and small-scale bioreactor simulators. Laboratory tests were conducted on fresh MSW collected from Solid Waste Management Plant Vilholi Nasik (MH), India. Hydraulic conductivity ranged between 9.70 × 10^–2 and 4.36 × 10^–4 cm/s. A direct shear test was conducted on MSW for different stages of degradation and found that the angle of shearing resistance decreases in a narrow range from 19° to 16° with the increase in degree of decomposition (DOD). At the same time, cohesion increases from 10 to 31 kPa as DOD increases. A strain of up to 1.2% was found in the MSW sample. This study also reports the laboratory measurement of pH, alkalinity, chemical oxygen demand (COD), and biogas. The biogas concentration for CO₂ has been reduced from 89 to 17%, while CH₄ concentration was increased from 10 to 63%. The modified Gompertz model was developed for cumulative biogas production.