Fig. 4From: A novel and simple approach to the good process performance of methane recovery from lignocellulosic biomass aloneSEM photos of rape straw. a Raw straw; b urea pretreatment; c fermented without treatment; d fermented with simultaneous urea treatment; e fermented with urea pretreatment; f fermented with simultaneous urea treatment and soil addition. I 100×; II 500×Back to article page