Lime sludge assisted anaerobic bioreactor landfilling of municipal solid waste for enhanced leachate stabilization and bioenergy yield

Abstract

Bioreactor landfilling even being advanced technology for enhanced stabilization of municipal solid waste (MSW), often suffers with adverse acidogenic conditions. Such conditions reinforce poor leachate stabilization, and reduced biomethane yield. This work attempts to counter the challenges of adverse MSW landfilling conditions through incorporation of waste alkaline sludge from paper industry. The amendment in anaerobic bioreactor landfilling of MSW was practiced by adding lime sludge (LS) with MSW in three distinct proportions: 20 g LS/kg MSW (LS100), 50 g LS/kg MSW (LS250) and 100 g LS/kg MSW (LS500), keeping LS0 as control. Periodic leachate and biomethane analysis showed benefits of proportionate LS addition. The control reactor often experienced leachate ponding and inhibitory conditions for anaerobic digestion. However, reactor LS250 achieved highest decrease in leachate organic strength removal (76.47 %) and biomethane production (8.315 L) over the period of landfilling. The pH and volatile fatty acids (VFAs) were in coordination with LS proportions. The LS addition beyond 100 g LS/kg MSW (LS500) could decrease the leachate pollution removal and biomethane yield. Finally, the Gompertz growth model showed excellent fit (R2 >0.997) to recorded biomethane. The study expands the scope of utilizing similar sludges for amendment of existing landfilling practices for efficient bioconversion of organic fractions of MSW.