Pulp & paper sludge (PPS) is a solid by-product of pulping and paper-making operations. The yield of PPS was 2628 × 104 t with 80% moisture content (MC) in 2007 in China, which would increase by 10% per year [4], most of the PPS is currently disposed of primarily in landfills or discarded carelessly in China. However, it is also attractive biomass feedstock for production of fermentation products such as ethanol [5–7], due to the high carbohydrate (such as cellulose, hemicellulose) content.