2. Materials and Methodss

2.1. Feedstock and inoculum

The materials used in this study included: grapes, maize and millet, which were collected from the shop in Xiamen city Fujian Province. The straw and grass was collected from village of Xiamen. Dried straws were chopped using a grinder (Hummer 900) to an approximate size of 2-3 mm. Inoculum was obtained from a laboratory-scale working pig manure digester that treated pig wastewater form the same pig farm.