Mechanical Pre-Treatment of Co-Digested Wastewater Sludge (WWS) and Brewery Spent Yeast (BSY) Under Anaerobic Condition

The food and beverage industries produce vast amounts of organic residue with the potential for biogas production. Among others, mechanical pre-treatment could be a useful option that enhances the biomethane yield of brewery-spent yeast and wastewater sludge. Therefore, this study investigates the co-digestion of brewery-spent yeast and wastewater sludge via mechanical pre-treatment to improve the biomethane yield. The co-digestion was carried out in 1: 2 of wastewater sludge to brewery spent yeast. A high-pressure homogenizer was used to mechanically pre-treat the WWS and (BSY) with 5-, 10-, and 15-minute exposure times. The proximate analysis was carried out, and biomethane potential was measured using the BMP AMPTS 11 setup. This study noticed a tremendous increase in biomethane yields compared to mono digestion; this can be traced to the co-digestion with wastewater sludge. The effect of co-digestion can be inferred to be more effective in the treatment with the best pre-treatment conditions. The treatment with 10 min exposure time released the highest volume of 175.30 Nml biogas. This can be traced to pre-treatment methods that have made the substrate accessible to biomethane-produced microorganisms. The pre-treatment improved the substrate's surface area, enabling sufficient interaction between the wastewater sludge, substrate, and microbes. Finally, this result shows the significant impact of mechanical pre-treatment, which is more noticeable than the effect of co-digestion.