Large amounts of coffee residues are generated from coffee processing plants in Ethiopia. These residues are toxic and possess serious environmental problems following the direct discharge into the nearby water bodies which cause serious environmental and health problems. This study was aimed to quantify wet coffee processing waste and estimate its bio-ethanol production. The study showed that the wastes are potential environmental problems and cause water pollution due to high organic component and acidic nature. The waste was hydrolyzed by dilute H2SO4 (0.2, 0.4, 0.6, 0.8 and 1 M) and distilled water. Total sugar content of the sample was determined titrimetrically and refractometry. Maximum value (90%) was obtained from hydrolysis by 0.4 M H2SO4. Ethanol production was monitored by gas chromatography. The optimum yield of ethanol (78%) was obtained from the sample hydrolyzed by 0.4 M H2SO4 for 1 h at hydrolysis temperature of 100 °C and after fermentation for 24 h and initial pH of 4.5. Based on the data, it was concluded that reuse of the main coffee industry wastes is of significant importance from environmental and economical view points. In conclusion, this study has proposed to utilize the wet coffee processing waste to produce bio-ethanol which provides the alternative energy source from waste biomass and solves the environmental waste disposal as well as human health problem.

This study aimed to determine bio-ethanol potential of poultry manure. The manure was hydrolyzed by dilute H 2 SO 4 (0.2, 0.4, 0.6, 0.8 and 1 M) at temperature of 100 and 130°C for 30 min. Maximum glucose (115.6 g/l) was obtained from hydrolysis of 100 g poultry manure by 0.8 M H 2 SO 4 at 100°C for 30 min. The study shows that treatment of poultry manure releases more total reducing sugar using 0.8 M H 2 SO 4. Refractometry analysis of the fermented hydrolysate gave maximum ethanol concentration of 5% w/v with 0.8 M H 2 SO 4 and 4, 4, 3 and 2.5% of ethanol with 1, 0.6, 0.4 and 0.2 M H 2 SO 4 hydrolysis at 130°C for 30 min, respectively. Treatment with 0.8 M acid is an effective way that results to maximum yield and treatment with 0.2 M acid is the least effective. The optimum fermentation time is 24 h.