Abstract
Biogas production from agricultural and industrial wastes delivers two benefits: on one side, the treatment of organic residues prevents the environmental and economic impact of their disposal; on the other side, methane and/or hydrogen are generated. The aims of this study were both to produce bio-hydrogen from buffalo wastes and to investigate the relationship between biogas production and bacterial and archaeal community composition. Anaerobic codigestion of livestock by-products (buffalo sludge and low protein cheese whey-scotta), with buffalo rumen and buffalo sludge as inoculum, was performed. The microbial community was analyzed using next-generation sequencing of 16S rRNA gene amplicons. Codigestion showed to be positive because of both sludge buffering capability and highly degradable carbohydrates content in scotta. Rumen inoculum proved more efficient compared to sludge during fermentation. In fact, cumulated production was higher (120.8 Vs 65.4 ml H2 g VS-1 respectively) and the average percentage of hydrogen in biogas was 48.1 (v/v) with maximum peak at 64.6. Moreover, rumen bacterial profile showed higher genera richness. Taxonomic classification showed that among the bacteria, Firmicutes, 23.3% of whom Clostridia; Bacteroidetes, and in particular Bacteroidia; Proteobacteria and Tenericutes, accounted for 88.2% of total sequences. Concerning the Clostridia Family XIII, the C. Incertae Sedis was the most represented (6.6%), and its quantity was twice as much in rumen inoculated hydrogen-producing samples than those non-producing. In the archaeal, community predominated the phylum Euryarcheota, with Methanobrevibacter the most represented, which was higher when hydrogen was produced with rumen inoculum. Studies on buffalo rumen as inoculum for hydrogen production are limited and this paper gives a first overview of microbial community composition by NGS in producing and non-producing samples.
Highlights
Biogas production by anaerobic digestion (AD) process from agricultural and industrial wastes delivers two benefits: on one side, the treatment of organic residues prevents the environmental and economic impact of their disposal; on the other side, energy carriers are generated
In trial T2, the hydrogen production started at day 5 with 27% (v/v in biogas) and increased to 55.6% at day 7 so being higher in BS2 than buffalo rumen fluid (BU) in trial T1, and resulted in 65.4 cumulated production
The hydrogen percentage in biogas was higher in T2 trial compared to T1 and both results were interesting if compared to what reported in literature from livestock manure and wastewater (Tang et al, 2008; Xing et al, 2010; Di Cristofaro et al, 2014) but BU
Summary
Biogas production by anaerobic digestion (AD) process from agricultural and industrial wastes delivers two benefits: on one side, the treatment of organic residues prevents the environmental and economic impact of their disposal; on the other side, energy carriers (methane and/or hydrogen) are generated. Current interest in the use of hydrogen as fuel, both for industrial applications and for road haulage, is because it has a high-energy density (122–142 kJ/g) and produced pollution is almost nil (Antonopoulou et al, 2008; Venetsaneas et al, 2009). The scotta has still a high organic load, environmentally pollutant if improperly managed, so cheese manufacturers would be extremely interested to make “scotta” an economic value by-product, avoiding costly disposal solutions
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