Improving Anaerobic Digestion Efficiency of Animal Manure Through Ball Milling Pretreatment

Anaerobic digestion (AD) offers a promising pathway for converting animal waste into biogas, improving waste management practices and generating renewable energy. However, the lignocellulosic structure of animal manure, particularly in dairy and cattle manure, hinders digestion efficiency and limits biogas yield. This study investigates the application of ball milling as a pretreatment strategy to enhance the anaerobic digestion of dairy manure. By reducing particle size and disrupting lignocellulosic structures, ball milling increases the bioavailability of organic matter, thus promoting microbial conversion and boosting biogas production. Experimental results reveal that 1-hour ball mill pretreatment increases biogas and biomethane production by 20% compared to untreated manure, achieving the same yield as digestion with 0.5% activated carbon addition. Furthermore, microbial community analysis indicates that anaerobic microbes remain largely unaffected by ball milling pretreatment, unlike the changes observed with activated carbon addition. These findings suggest that ball milling is a practical, adaptable, and scalable pretreatment method to enhance the anaerobic digestion efficiency of dairy manure. It offers a sustainable solution for improved manure management and biogas production.