Bioenergy recovery analysis from various waste substrates by employing a novel industrial scale AD plant

In this novel industrial scale case study, the bioenergy recovery based on sole and mixed cow-buffalo (CBM) and potato waste (PW) substrates has been analyzed in real time, i.e., on-site on a full-scale operational anaerobic digestion (AD) plant. The plant employed in this study is a novel design, consisting of tri-digesters connected via an underground upflow anaerobic sludge blanket (UASB) type lagoon allowing it to function as a continuous-flow reactor. The system has been further equipped with CSTR, microwave heating, gas scrubbers, compression, and storage systems. The highest energy recovery readings were 123.9 m³/1,000 kg, 77 m³/1,000 kg, and 151.6 kWh/1,000 kg in terms of biogas, bio-methane, and electricity generated, respectively, with 75:25 ratio of CBM:PW. Operating with 100% CBM, yields of 79.9 m³/1,000 kg, 47 m³/1,000 kg, and 95 kWh/1,000 kg were obtained. The percentage of recovery in bio-methane production increased on using the mixed substrates, but it was the lowest with a 25:75 ratio of CBM:PW. The electrical power generation efficiency was found to be significantly increased, but not distinctively with the plant aggregate power rating that was probably associated with the variable quality of biogas which was fed to the power generator. A linear regression analysis had shown a significant and positive correlation between the rate of VS removal and biogas yield.