Coffee pulp is the first waste product obtained during the wet processing of coffee beans. Coffee pulp makes up nearly 40% of the total weight of the coffee cherry. Coffee pulp contains 25.88% of cellulose, 3.6% of hemicel- luloses, and 20.07% of lignin. Coffee pulp is considered as an ideal substrate of lignocellulose biomass for micro- bial fermentation to produce such value-added products as ethanol. In this study, we used alkaline pre-treatment of the coffee pulp with NaOH (0.2 g/g biomass) in a microwave system at 120°C during 20 min. This method gave the best results: 71.25% of cellulose remained, and 46.11% of hemicellulose and 76.63% of lignin were removed. After that, the pre-treated biomass was hydrolyzed by Viscozyme Cassava C (enzyme loading was 19.27 FPU/g) at 50°C for 72 hours. The results showed that the highest reducing sugars and glucose concentration after hydrolysis were 38.21 g/l and 30.36 g/l, respectively. Then, the hydrolysis solution was fermented by S. cerevisiae (3.108 cells/ml) at 30°C for 72 hours. The highest concentration of ethanol obtained was 11.28 g/l. The result illustrated that, available and non- edible as it is, coffee pulp could be a potential feedstock for bioethanol production in Vietnam.
Economic Extraction and Recovery of REEs and Production of Clean Value-Added Products from Low-Rank Coal Fly Ash
