Effects of Nutrients Supplementation on Enhanced Biogas Production from Maize Silage and Cattle Slurry Mixture

This study investigated the effects of nutrients supplementation during codigestion of maize silage and cattle slurry. Batch anaerobic biodegradability tests lasted 20days under mesophilic conditions, and an organic loading rate of 5.0g VS (volatile solids)/L were done. Biogas yield increased with the dose of the cattle feed supplement up to 894L/kg VS, which was 65% higher than in the control reactor. Similarly, the cumulative biogas production rate (CBPR) increased with successive increase in the dose of feed supplement. Supplementation enabled efficient volatile fatty acids (VFA) elimination and pH increasing; however, the best VFA/TA ratio was achieved with feed supplementation of 25mg/g of feedstock, providing the highest rate of biogas production (k=0.22/d). The highest increase in biogas production of 8.0mL/mg was achieved with the lowest nutrient supplement dosage. Based on these results, it can be recommended that a supply of feed supplement at a ratio of 0.5% of the fresh mass provide considerably increasing biogas production.