Leachate recirculation in a laboratory-tested bioreactor landfill: Effects of biodegradation

The amount of waste generated in Bandung City taken to the Sarimukti TPA (final processing site) exceeds 30% of the total generation.This is not by Presidential Decree no.97/2017, which places landfills at the bottom of the hierarchy because waste decomposition takes 30-50 years and can potentially become an environmental problem in leachate pollution, landfill gas emissions, and disease vectors.The landfill bioreactor innovation is a reactor with a microbiological process that can accelerate the decomposition and stabilization of waste.The landfill bioreactor was operated anaerobically for 138 days.Waste in the landfill bioreactor produces leachate, which is used for recirculation.Leachate recirculation improves physical, chemical, and biological conditions, thereby stabilizing biodegradation and waste.The biodegradation rate is reviewed based on leachate, gas, and settlement parameters.Leachate recirculation variations are 0%, 6%, and 12% of the reactor volume.Leachate recirculation of 12% (120 L/day) is thought to be able to increase the degradation rate, indicated by a more significant COD removal efficiency, 85.82%, compared to recirculation of 6% (60 L/day), 77.87%.This is also supported by the measured settlement rate (decrease in the waste surface), recirculation 12%, 16.61%, compared to recirculation 6%, 9.13%, and without recirculation, 4.02%.However, methane gas (CH 4 ) production in recirculation 6% has an average of 0.034 L/day higher than recirculation 12%, which is 0.027 L/day.This is thought to be due to the presence of an inhibitor in the form of O 2, due to the higher injection volume of the leachate recirculation process at recirculation 12%.Apart from that, it is also suspected that gas is difficult to release into the atmosphere because the waste condition is increasingly saturated, which is indicated by vertical permeability.Apart from that, the waste condition is starting to become saturated, compressing the pore space, making it difficult for gas to be released.The MANOVA test with Minitab was used to identify the effect of leachate recirculation on biodegradation rates (COD and methane parameters) and settlement.The results show an influence of the leachate recirculation volume on the rate of biodegradation (methane and COD gas parameters) and settlement.