Bean dregs wastes, used as substrate, came from Shanghai University canteen. In dry basis, bean dregs present a high content in cellulose (about 70 wt%). Before the experiments, the dried bean
dregs were milled for 10 min using a mixer (HR170, Philips Corp.) at the maximum speed setting, and then were sieved. The portion under 140 mesh was collected for tests. Bean dregs were suspended in deionized water to about 3.3 wt% solids content (1 g in 30ml of deionized water). Then, the feeding suspension was injected into a batch reactor when the temperature and pressure of the vessel got to the condition of experiment.