Biogas production from wheat straw pre-treated with ligninolytic fungi and co-digestion with pig slurry

This study carried out for the first time a comparison among ligninolytic (white-rot) and cellulosolytic or xylanolytic (Trichoderma) pre-treated wheat straw, for biogas production, potential, without or with pig slurry in co-digestion. Methane (CH4) production from wheat straw pre-treated for 4 and 10 weeks with seven different fungal isolates was preliminarily measured. Then, the effects on biogas yield of the co-digestion with pig slurry were checked on straw pre-treated with 3 selected fungal strains. The maximum production of CH4 from pre-treated straw with Ceriporiopsis subvermispora (SUB) for 4 and 10 weeks was higher than the control (16% and 37%, respectively). The accumulation daily rate was higher than control (42% and 81%, respectively). A positive correlation between CH4 accumulation daily rate and straw enzymatic digestibility was found. In co-digestion with pig slurry, SUB pre-treated straw for 10 weeks showed an accumulation daily rate of 17.4 mL d-1 g-1 VS, significantly higher (17%) than that of the control. The time to reach the maximum CH4 production was shortened on average from 34 to 21 days in co-digestion with pig slurry, in comparison with pre-treated mono-digested wheat straw. The biological pre-treatment with selected white-rot fungi appears a promising technology to increase methane production from wheat straw.