Anaerobic co-digestion of cattle rumen content and food waste for biogas production: Establishment of co-digestion ratios and kinetic studies

Abstract

This study investigated the batch co-digestion of cattle rumen content (CRC) and food waste (FW) for biogas production in different ratios (CRC:FW) to assess biogas production and process stability. The results showed that CRC and FW possess characteristics that are desirable for biogas production as seen in their respective total solids (10.85 and 26.53%), volatile solids (89 and 86.83%) and carbon to nitrogen ratio (23.7 and 15.7) values. Co-digestion improved carbon to nitrogen ratio, biogas yield and pH of the co-substrate compared to individual substrates. The 50:50 co-digestion ratio was found to be optimum as it gave the maximum cumulative biogas yield of 320.52 ml/gVSadded. Co-digestion also improved the pH, volatile fatty acid (VFA) and total ammonia nitrogen (TAN) characteristics during digestion. The cone model was able to adequately represent the kinetics of the process. These findings have provided very useful insights into the co-digestion of CRC and FW.