Role of pine needle biochar in operation and stability of anaerobic processes

Utility of biochar addition in anaerobic processes for promoting direct interspecies electron transfer (DIET) is demonstrated in this research. Biochar produced from pyrolysis of pine needle forest residue was used as conductive material for DIET. Three CSTRs were operated in parallel with and without biochar addition in fed-batch mode. Reactor without biochar which represented indirect interspecies electron transfer (IIET) exhibited wide variation in pH and VFA and took longer period during startup. All the rectors were operated at steady state with an OLR ranging from 0.5 to 1.75 kg-COD/m³.d. As OLR increased, performance of reactor without biochar resulted in rapid pH drop and increase in VFA, leading to its eventual failure at OLR of 1.75 kg-COD/m³.d. As against to this, performance of reactors with biochar remained robust and relatively unaffected at higher OLR values. Daily VFA accumulation from fed-batch mode always remained highest in reactor without biochar.