A method for shifting of cattle dung based biogas digester for enhanced anaerobic co-digestion of cattle dung with leaf litter of neem

In India, many biogas plants process cattle dung (CD). At the same time, an excessive amount of litter of leaves is swept and burnt. The paper investigates small-scale integration of leaf litter of neem (LLN) to the operational CD-based biogas plant under mesophilic conditions. The introduction of LLN at the volatile solid ratio of 1:4 (LLN:CD) respectively increased daily biogas production, specific methane yield, and the resultant electrical energy by 13.11, 15.26, and 15.02% and reduced the proportion of CO₂ by 5.85%. However, because of the energy required to pulverize the LLN in CD-LLN–based, the net percentage increase of the electrical energy dropped to 13.59%. CD-LLN–based reactor also produced 56.34% higher electrical energy per organic substrate added and performed well by 15.0% in terms of CO₂ emission compared to CD-based. Digester performance was seriously unaffected during the transition stage. The study highlights another way of managing LLN and shifting anaerobic reactors from one feedstock to another.