Monte Carlo-based model for estimating methane generation potential and electric energy recovery in swine wastewater treated in UASB systems

This work aimed to develop a mathematical model based on Monte Carlo simulation to predict the energy potential of biogas produced in an up-flow anaerobic sludge blanket (UASB) reactor treating swine wastewater (SWW) for a farm with up to 10,000 pigs. In order to determine the SWW energy potential, various organic loading rates (OLRs) were studied in lab-scale experiments, complemented with information found in the literature. Then, the energy potential of biogas was evaluated considering three categories of pig farms (small, medium, and large), which corresponded to different scales (250, 500, and 1000 pigs). The potential for electrical energy recovery was 227.0, 500.8, and 1103.6 kWh d-1 for small, medium, and large-scale pig farm, respectively. The simulation results show that the model allowed an estimation close to reality, with reduced errors. R2 value of 0.934 was found to estimate methane and electric energy flow as a function of the removed load, and 0.823 in terms of reactor inflow function. Thus, the model proved to be a relevant tool for entrepreneurship, and its use can enable studies to implement energy self-sufficiency projects. It was also inferred that biogas plants have great potential for profitability in electricity generation and cost reduction in projects. In conclusion, this research presents an alternative model for estimating methane and electrical energy potential for UASB reactors treating SWW.