Bu-Ali Sina University Biosystems Engineering and Sustainable Technologies 3092-7331 1 2 2025 12 01 Modeling and Optimizing an Aerobic Co-digestion Based on Optimal-Mixture Design 31 50 6464 10.22084/best.2025.31593.1011 EN Ezatolah Azadi Department of Biosystems Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. 0000-0001-6904-2442 Majid Rasouli Department of Biosystems Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran. 0000-0001-6904-2442 Moloud Jafari Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), Montreal, Canada. 0000-0003-2802-0954 Journal Article 2025 09 18 A mesophilic co-digestion of sugarcane straw and sewage sludge with long hydraulic retention time in lab-scale reactors has been studied. Anaerobic biodegradability was examined in a biochemical methane potential (BMP) testing apparatus using 500 ml bottles. Both the design of the experiment method and the I-optimal mixture design were used as a mixed design strategy to systematically optimize the substrate composition ratios and elucidate the possible synergistic effects for an anaerobic co-digestion system. A reduced cubic model was created by Design-Expert software as a function of substrate composition ratios. The model was experimentally validated by the ANOVA method. Based on the observations, all linear impacts and interactions between substrates showed synergistic effects on the biogas production rate. The optimum proportions of the feedstock were 0.28% (w/w) of Primary sludge (A), 48.98% (w/w) of Secondary sludge (B), and 50.73% (w/w) of sugarcane straw (C). Also, according to the aforementioned optimum proportions, cumulative biogas reaches the maximum level of 8.581 L during 150 days. https://best.basu.ac.ir/article_6464_894a9b94bcc5969b60bd18e8ea9c0ddc.pdf