Fungal pretreatment parameters for improving methane generation from anaerobic digestion of corn silage

Corn silage was treated by white rot fungi (WRF) to investigate the effect of pretreatment on material's ability to produce methane in anaerobic digestion (AD). The selective fungi Pleurotus ostreatus and Dichomitus squalens promoted biogas generation, whereas the non-selective Trametes versicolor and Irpex lacteus had negative effect. Cumulative methane production after 10-day pretreatment with P. ostreatus at 28 degrees C rose 1.55-fold. The longer pretreatments of 30 and 60-days had smaller effect. When the pretreatment with P. ostreatus was carried out at 40 degrees C a high H2S release affected the AD process. Effect of WRF action dependent on the type of corn silage. With typical corn silage, the lignin depolymerisation raised the methane generation from 0.301 to 0.465 m(3) kg vs(-1). In contrast, extensive decomposition of hemicellulose in hybrid corn silage deteriorated the effect of pretreatment on methane production.