Whole Plant Modeling to Optimize the Biogas Production in Anaerobic Digesters

Anaerobic digestion is a complex system of biochemical and physical processes. Due to the complexity of the process, it has traditionally been treated as a black box system, and optimization has been based on experience or trial and error methods. However, simulation modeling can be a useful tool for process understanding and optimization of this process unit operation. This study aims to assess the use of a calibrated and validated simulation model in order to evaluate biogas production capacity and potential of wastewater treatment plants to offset energy costs.The results from the validation studies showed that the biogas production could be predicted by using the General Activated Sludge – Digestion Model (ASDM) built in BioWin™ process simulator. Sensitivity analysis indicated that the hydrolysis rate has tremendous effect on the model predictions and this may have to be modified during the model calibration to predict plant performance. Furthermore, the biogas production proved to be highly affected by the characteristics of the anaerobic digester's influent. The effects of design and operational parameters on the performance of biogas production were also assessed by using a calibrated and a validated model. Overall, this study concluded that an integrated anaerobic digestion simulation model can be utilized to simulate biogas production and to optimize the design and operational parameters of the digesters.