Mathematical modelling of biogas yield from a greenhouse biogas digester fed with cow dung
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Date
2024-07
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Publisher
University of Fort Hare
Abstract
This study investigated biogas optimization using a solar greenhouse digester with cow manure feedstock. The methodology involved physicochemical analysis of feedstock, continuous monitoring of operational parameters, and development of mathematical models. A thermal analysis of the system was conducted. The temperature sensors were strategically positioned within the balloon digester and greenhouse envelope, while meteorological factors were measured using a pyranometer and weather sensors.
The results demonstrated optimal performance at mesophilic temperatures (35±1°C) and pH range of 6.8-7.2. Over the 39-day retention period, the system produced 18.269 cubic meters of biogas, comprising 58% methane (CH4) and 41% carbon dioxide. The process achieved a chemical oxygen demand (COD) destruction rate of 56.31%. The low COD destruction rate can be attributed to the system's lack of a stirring mechanism, which affected the biogas yield and its composition. The multiple linear regression model for temperature prediction achieved an R-squared value of 0.985, and with a root mean square error (RMSE) of 0.341 while the non-linear response surface model for biogas yield reached 0.986 with a root mean square error (RMSE) of 0.0239.
The greenhouse enclosure effectively maintained optimal conditions, enhancing microbial activity and biogas production efficiency. These findings advance the understanding of solar assisted biogas systems for sustainable energy production.
Description
Masters dissertation
Keywords
Biogas, Sewage -- Purification -- Anaerobic treatment, Renewable energy sources, Mathematical models
Citation
Mzobotshe, M. (2024) Mathematical modelling of biogas yield from a greenhouse biogas digester fed with cow dung. MSc (Physics) dissertation. Alice, South Africa: University of Fort Hare.