Modified landfill gas generation rate model of first-order kinetics and two-stage reaction

Abstract

This investigation was carried out to establish a new domestic landfill gas (LFG) generation rate model that takes into account the impact of leachate recirculation. The first-order kinetics and two-stage reaction (FKTSR) model of the LFG generation rate includes mechanisms of the nutrient balance for biochemical reaction in two main stages. In this study, the FKTSR model was modified by the introduction of the outflow function and the organic acid conversion coefficient in order to represent the in-situ condition of nutrient loss through leachate. Laboratory experiments were carried out to simulate the impact of leachate recirculation and verify the modified FKTSR model. The model calibration was then calculated by using the experimental data. The results suggested that the new model was in line with the experimental data. The main parameters of the modified FKTSR model, including the LFG production potential (L₀), the reaction rate constant in the first stage (K₁), and the reaction rate constant in the second stage (K₂) of 64.746 L, 0.202 d^−1, and 0.338 d^−1, respectively, were comparable to the old ones of 42.069 L, 0.231 d^−1, and 0.231 d^−1. The new model is better able to explain the mechanisms involved in LFG generation.

Keywords

landfill gas (LFG) / generation rate model / first-order kinetics / two-stage reaction / outflow function