Co-digestion of solid waste: Towards a simple model to predict methane production

Abstract

Modeling methane production is a key issue for solid waste co-digestion. Here, the effect of a step-wise increase in the organic loading rate (OLR) on reactor performance was investigated, and four new models were evaluated to predict methane yields using data acquired in batch mode. Four co-digestion experiments of mixtures of 2 solid substrates were conducted in semi-continuous mode. Experimental methane yields were always higher than the BMP values of mixtures calculated from the BMP of each substrate, highlighting the importance of endogenous production (methane produced from auto-degradation of microbial community and generated solids). The experimental methane productions under increasing OLRs corresponded well to the modeled data using the model with constant endogenous production and kinetics identified at 80% from total batch time. This model provides a simple and useful tool for technical design consultancies and plant operators to optimize the co-digestion and the choice of the OLRs.

Existing Empirical Kinetic Models in Biochemical Methane Potential (BMP) Testing, Their Selection and Numerical Solution

“…Biochemical Methane Potential (BMP) tests are used to determine the anaerobic degradability of waste [1] or the possibility to recover energy from wastewater as a combustible gaseous mixture containing methane, typically referred to as biogas [2]. Both goals require the modeling and parametrization of the process for further scaling up or transition from a batch to a continuous flow process [3]. Models can be useful to determine the duration of the inoculum adaptation period, to estimate maximum biomethane yield and conversion rate of the substrate of interest into energy carrier, a biomethane [4].…”

“…Very often this model is used with no lag-phase, i.e., when t lag = 0 2. The specific time model can be also found under name of first-order inverse time model,3 also called a first-order kinetics with modified time dependency 4. Cauchy distribution can be met under name of Lorentzian function 5.…”

Modelagem da cinética da digestão anaeróbia dos resíduos gerados no processamento de café solúvel

“…Um ambiente anaeróbio é uma das condições básicas para o crescimento de microrganismos metanogênicos estritamente anaeróbios usando o potencial de óxido-redução como base de julgamento (XIN; HE; QIU, 2018). A taxa de carregamento orgânico (TCO) afeta diretamente no equilíbrio entre substrato e microrganismos que além disso precisam ser regulado para manter o equilíbrio entre acidificação e metanogênese (KOUAS et al, 2018;WU, 2019).…”