Self-fermentation of cellulosic substrates to produce biohydrogen without inoculum addition nor pretreatments was investigated. Dark fermentation of two different substrates made of leaf-shaped vegetable refuses (V) and leaf-shaped vegetable refuses plus potato peels (VP), was taken in consideration. Batch experiments were carried out, under two mesophilic anaerobic conditions (28 and 37°C), in order to isolate and to identify potential H2-producing bacterial strains contained in the vegetable extracts. The effect of initial glucose concentration (at 1, 5 and 10g/L) on fermentative H2production by the isolates was also evaluated.H2production from self-fermentation of both biomasses was found to be feasible, without methane evolution, showing the highest yield for V biomass at 28°C (24L/kgVS). The pH control of the culture medium proved to be a critical parameter. The isolates had sequence similarities ≥98% with already known strains, belonging to the family Enterobacteriaceae (γ-proteobacteria) and Streptococcaceae (Firmicutes). Four genera found in the samples, namely Pectobacterium, Raoultella, Rahnella and Lactococcus have not been previously described for H2production from glucose. The isolates showed higher yield (1.6-2.2molH2/molglucoseadded) at low glucose concentration (1g/L), while the maximum H2production ranged from 410 to 1016mL/L and was obtained at a substrate concentration of 10g/L. The results suggested that vegetable waste can be effectively used as both, substrate and source of suitable microflora for bio-hydrogen production. © 2014 Elsevier Ltd.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment