Performance and kinetic analysis of biogas production from co-digestion of landfill leachate with pineapple peel in batch experiments

Abstract

This study examines the co-digestion of landfill leachate (LFL) with pineapple peel, focusing on biogas production. The study was conducted with a lab-scale batch anaerobic digester using a 30 L working volume batch completely mixed reactor at 35 °C to investigate the monodigestion of leachate and of pineapple peel and their co-digestion with three different mixing ratios. The results of all of the experiments in the study were fitted with first-order kinetic models to compare the behavior of different batches through rate constants (k). As expected, the anaerobic digestion of 25 L leachate achieved a biogas yield of 38 L kg⁻¹ volatile solids (VS)_consumed and a VS removal efficiency of 30%, both markedly lower than those achieved with 3 kg VS pineapple peel per m³ in 25 L tap water (513 L kg⁻¹ VS_consumed biogas yield and 80% VS removal efficiency). The leachate, which had a fixed volume of 25 L, was mixed with 1, 2, and 3 kg VS pineapple peel m⁻³. The results showed that co-digestion with 2 kg VS pineapple peel m⁻³ achieved the highest biogas yield of 431 L kg⁻¹ VS_consumed and approximately 80% VS and 90% chemical oxygen demand (COD) removal efficiency with stable conditions in the reactor. The first-order kinetics equation was selected to characterize the anaerobic digestion and was able to describe and compare the anaerobic digestion processes of the experiments. The rate constants (k) were 0.25, 0.22, and 0.18 day⁻¹ for co-digestion with 1, 2, and 3 kg VS pineapple peel m⁻³.