Simplex Centroid Mixture Design for Optimizing and Promoting the Anaerobic Co-Digestion Performance of Sheep Blood and Cheese Whey

Reduced emissions of greenhouse gases and global warming can be made possible by discovering alternative energies and reduced dependence on fossil fuels. Biogas is considered as one of the alternatives to fossil fuels. This study investigates anaerobic co-digestion for the development of biogas with sheep blood and cheese whey. Digested cow manure was used as inoculum. Using the Design Expert ۱۰ program and within the context of mixture design, the experiments were designed. Then, ۲۲ experimental digesters with a volume of ۵۰۰ mL were considered for doing the experiments considering the design output provided by the software. Each one was filled with ۳۰۰ mL of different compositions of three matters. The digesters were kept in the mesophilic temperature range (۳۷ °C ) for ۲۱ days. Biogas was measured using the BMP test on a daily basis. According to the experimental findings, the best composition included ۳۵ % sheep blood, ۳۵ % cheese whey, and ۳۰ % inoculum. This biogas composition produced a biogas yield of ۱۴۶.۶۶ mL/g vs. The amount of methane production in this compound was ۷۳.۳۳ mL/g vs. After modeling, the Design Expert software predicted an optimal composition including ۴۴ % sheep blood, ۲۴ % cheese whey, and ۳۲ % inoculum. Biogas yield of this prediction was ۱۴۳ mL/g vs. The findings show that in order to overcome acidification in digestion of matters such as cheese whey, a composition of matters with higher pH stability can be used to increase the amount of biogas and methane produced in a particular period. Furthermore, using inoculum accelerates the digestion operations due to existence of many microorganisms and saves time and energy.

Keywords:

Slaughterhouse waste , Biogas , Biochemical methane potential test , optimization , Response Surface Methodology