4. Conclusions
The study demonstrated the potential of biomethanation of vegetable waste in ABR resulting in biogas and methane yields of around 0.7–0.8 L biogas/g VS added/d and 0.42–0.52L methane/g VS added/d. Effluent recirculation resulted in improved biogas pro- duction with complete effluent recycle (100%) being optimum thereby achieving a carbon recovery factor of 96.7% of input car- bon. By this strategy, close to infinite sludge retention time and efficient phase separation could be achieved without affecting the stratification of microbial communities. Future studies need to focus on characterization of chamber specific microbial commu- nities and operation of reactor at higher OLRs and shorter HRTs.