Examining a Pretty Simple and Low Cost Method for Modeling of Biogas Production from Biodegradable Solids

Abstract

This paper evaluates the application of consecutive multistage first order kinetics for mathematical modeling of biogas generation trend during anaerobic digestion (AD) of typical farm-based biodegradable solids within batch reactors. The input parameters of the model are mass of biodegradables (as VM), initial content of total volatile fatty acids (TVFA) and recorded values of biogas or methane production. Multistage consecutive equations of first order reaction in combination with numerical solution procedure for multi-parameter differential equations can provide a pretty high precision modeling of biogas production and consequently estimation of achievable energy from biodegradable solids even though it is less sophisticated than frequently used AD models. Four types of biodegradable solids including pig feces, hot water-treated cotton stalks, rice straw and dairy manure were examined through bench-scale experiments at mesophilic conditions in order to determine the biogas production potential as well as the first order kinetic constants for consecutive stages of the process. All modeling trials produced reasonable output regarding the fitting between model predicted values and experimental results. The best fitted first order rate constants of hydrolysis, acidogenesis and methanogensis obtained from the observed data were in the range of 0.022 to 0.105 d -1 , 0.106 to 0.970d -1 , and 0.140 to 2.300d -1 respectively. Determination of initial content of volatile fatty acids could increase the goodness of fit between the model and experimental data. The proposed modeling procedure can predict the biogas generation trend within 10% accuracy.

Biochemical, morphological, and yield responses of lady's finger plants to varying ratios of palm oil mill waste (decanter cake) application as a bio-fertilizer

“…The applicability of a first-order model depends to a large extent on the characteristics and quality of inoculums and that some of the variability in the kinetic constants in models is dictated by the inoculum (Neves et al 2008). The kinetic of CH 4 production from fiber digestion has previously been modeled as a first-order reaction (Kang et al 2014;Adl et al 2015;Castano 2012). However, the comparison of the results from this study with values of the reaction rate constant reported in literature should be conducted cautiously because some studies report the first-order kinetic of the hydrolysis step rather than the entire methane production process.…”

“…Analogously, adaptation and enrichment of mixed anaerobic culture could be used to develop and intensify the lignocellulose (cellulose and hemicellulose) degrading activity in the culture. Although some studies reported biomethane production from lignocellulosic substrates at mesophilic and thermophilic conditions (Adl et al 2015;Janke et al 2015;Kang et al 2014), very few studies (Saady and Massé 2013) have been published on psychrophilic anaerobic digestion of cellulose and hemicellulose. Little is known about the culture kinetics when integrating low temperature with feeding lignocellulose substrate.…”

Restoring the Stability of Long-Term Operated Thermophilic Anaerobic Digestion of Maize Straw by Supplying Trace Elements

“…When considering the substrate composition, amount of substrate to be treated, and process economy, a plug flow reactor was used because it is known for its lower cost, more stable performance, and ability to withstand environmental stress [23]. Moreover, researchers have also investigated the effectiveness of plug flow reactors on organic substrates with solid content in the range of 11-14% total solids (TS) [24,25]. Biogas production in a plug-flow reactor may be more favorable than in a typical reactor [26], and the role of trace elements in a plug-flow reactor may be different, but this is unknown at this time.…”

Dual-pool, three-phase kinetic model of anaerobic digestion in batch mode

“…With the growing interest and investment in the biogas production industry, modelling is paramount for a better understanding of the anaerobic digestion process ( Gerber and Span, 2008 ; Gustafsson et al, 2020 ). The determination of the degradation kinetics and the maximum volume of biogas that can be extracted from a given substrate is essential in reactor design and performance control ( Adl et al, 2015 ). These parameters are obtained from anaerobic digestion batch assays, which can be quite time-consuming due to long retention times.…”