Modeling and Investigating the Impact of Fermentation on the Anaerobic Digestion of Waste Sludges

In this research, the impact of fermentation on waste activated sludge (WAS), primary sludge (PS), and integrated WAS+PS were studied by BioWin® simulation software. The effect of SRT digester and fermentation were studied for SRT of 10, 20, and 30 days. The impact of fermentation and SRT was found proportional to the biodegradability of the raw sludges. Fermentation improved volatile suspension solids reduction (VSR), biodegradability, and methane production as SRT increased for all cases (i.e., WAS, PS, and PS+WAS). The simulation results of WAS indicated that the VSR increased up to 18% compared to the base model. In PS fermentation, VSR capability was as high as 25%, 43%, and 52% for SRT of 10, 20, and 30 days, respectively. The maximum effect of fermentation was observed for PS+WAS with SRT of 30 days in comparison to the base model scenario by implementing the integrated PS and WAS.