Semi-continuous application of leachate and septic tank effluent to increase and accelerate biogas production in landfills

In this study, the bioreactors were constructed as systems designed to simulate waste degradation and biogas generation in landfills, promoting greater environmental control and contributing to the Sustainable Development Goals, particularly SDG 7 (Affordable and Clean Energy), SDG 11 (Sustainable Cities and Communities), and SDG 13 (Climate Action). Their use enables sustainable strategies for leachate management, percolate recirculation, and energy recovery. This study evaluated biogas production in 1,000 L reactors filled with municipal solid waste and subjected to semi-continuous application of raw leachate, concentrated leachate, and septic tank effluent, simulating seasonal dry and rainy conditions. The experiment was conducted over a 12-month period, with daily measurements of biogas composition and flow. The results show that leachate recirculation significantly increased methane production in both seasons, whereas septic tank effluent had a positive effect primarily during the dry period. The findings highlight the potential of leachate recirculation as an environmentally sound strategy to enhance anaerobic digestion, reduce greenhouse gas emissions, and strengthen sustainable solutions for landfill management.