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Physic Nut Seed Cake Methanation and Chemical Characterization of Anaerobic Bio-digested Substrate

Gavilanes, Freddy Zambrano, Guedes, Carmen Luísa Barbosa, Silva, Helder Rodrigues, Nomura, Rafael Guayato, Andrade, Diva Souza
Waste and biomass valorization 2019 v.10 no.5 pp. 1267-1276
anaerobic digesters, anaerobic digestion, biofertilizers, biogas, biomass, energy, inoculum, jatropha cake, methane, methane production, pig manure
Methane (CH₄) generation from the anaerobic digestion of vegetal biomass is an important clean alternative form of energy. In this context, the response of the physic nut seed cake to microbial inoculum for biogas and CH₄ production was examined in lab-scale biogas anaerobic digesters. Two experiments were carried out with physic nut seed cake stored over 6 and 18 months. The treatments assayed in each one of these experiments included five types of inoculum: water as the control, three different consortia of bacterial isolates from Jatropha seed cake and one bacterial consortium from bio-digested swine manure. The cake stored for 18 months with water showed the highest volume of biogas, with 83.67 mL in 6.54 g of cake after 21 days, but with lower production of CH₄. The best concentration of CH₄ (84.33%) was obtained from the Jatropha seed cake stored for 18 months when co-digested with the consortium of 14 bacterial isolates. Co-digestion of physic nut seed cake with the bacterial consortium of isolates from Jatropha cake was the best for producing CH₄. After anaerobic digestion, substrates had an increase in macro and micronutrient contents, showing potential for biofertilizer production.