Complementary effluents assessment and Metagenomic analysis in Hybrid anaerobic reactor

A hybrid anaerobic reactor (HAR) operated to digest brewery wastewater, complemented with piggery effluent (60% and 40% v/v, respectively), under three hydraulic retention times (HRT): 5.7, 3.0 and 1.0 d. Biogas productivity was 0.9 L/L.d (64% CH4), 1.2 L/L.d (77-78% CH4), and 2.9 L/L.d (80% CH4), respectively. The microbial characterization was assessed by Next Generation Sequencing of the 16S rRNA gene, and showed a diverse bacterial population in both effluents. These populations belonged mostly to phyla Bacteroidetes (53 %) on BWW, and Firmicutes (65 %) on PE which became predominant throughout the experiment (up to 65% on HRT 1.0 d). Most of Bacteroidetes were affiliated with Bacteroidales (53%) and most of Firmicutes were affiliated with Clostridiales (57 %). The presence of Methanosaeta genus was found to be detected as the main archaeal populations at the end of the anaerobic digestion, suggesting that the acetoclastic pathway was the main way for methane production.