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Mesophilic anaerobic digestion of pig slurry and fruit and vegetable waste: Dissection of the microbial community structure

Ros, Margarita, de Souza Oliveira Filho, Jose, Perez Murcia, Maria Dolores, Bustamante, Maria Angeles, Moral, Raul, Coll, Maria Dolores, Lopez Santisima-Trinidad, Ana Belen, Pascual, Jose Antonio
Journal of cleaner production 2017 v.156 pp. 757-765
Bacteroidetes, Firmicutes, Methanobrevibacter, Methanosaeta, anaerobic digestion, bacteria, biogas, community structure, methane, methane production, methanogens, microbial communities, pig manure, proteolysis, sludge, tomatoes
This paper studies the abiotic properties and the microbial community of a pilot scale digester with a working volume capacity of 300 L. The system worked at mesophilic operating conditions, with several organic load rates formed by a mixture of different ratios between waste A (fruit and vegetable sludge + tomato waste) and waste B (pig slurry). The core group of microorganisms corresponding to the ratio 70% A:30% B, showed the highest methane production (60%). This core group included bacteria, principally Firmicutes and Bacteroidetes, involved in cellulolytic degradation, proteolysis and acidogenesis, as well as a concomitance between acetotrophic, mainly Methanosaeta methanogens and hydrogenotrophic, principally Methanosphaera and Methanobrevibacter methanogens. An increase of the proportion of waste B (pig slurry) to 50–60% resulted in a decrease of the production of biogas and methane, which unbalanced the methanogenic bacteria, increasing the amount of principally hydrogenotropic methanogens (Methanosphaera and Methanobrevibacter).