Bioconversion of algae to methane and subsequent utilization of digestate for algae cultivation: A closed loop bioenergy generation process

The present investigation was targeted on anaerobic digestion of Chroococcus sp. and utilization of resul- tant ‘‘Liquid Digestate’’ for its further biomass production. The algal biomass has biomethane potential of 317.31 ± 1.9 mL CH4 g1 VSfed. Regular process monitoring revealed that process was stable throughout the experiments. The ‘‘Liquid Digestate’’ was explored as nutrient supplement for further algal growth. Diluted ‘‘Liquid Digestate’’ (30% concentration) was found optimal for algal growth (0.79 ± 0.064 g L1). Simultaneously, 69.99–89.31% removal in nutrient and sCOD was also recorded with algal growth. Inter- estingly, higher growth was observed when rural sector wastewater (1.29 ± 0.067 g L1) and BG11 broth (1.42 ± 0.102 g L1) was used for diluting the ‘‘Liquid Digestate’’. The current findings have practically proven the feasibility of hypothesized ‘‘closed loop process’’.